1 # Ocean Interpreter - Jamison Creek version
3 Ocean is intended to be a compiled language, so this interpreter is
4 not targeted at being the final product. It is, rather, an intermediate
5 stage and fills that role in two distinct ways.
7 Firstly, it exists as a platform to experiment with the early language
8 design. An interpreter is easy to write and easy to get working, so
9 the barrier for entry is lower if I aim to start with an interpreter.
11 Secondly, the plan for the Ocean compiler is to write it in the
12 [Ocean language](http://ocean-lang.org). To achieve this we naturally
13 need some sort of boot-strap process and this interpreter - written in
14 portable C - will fill that role. It will be used to bootstrap the
17 Two features that are not needed to fill either of these roles are
18 performance and completeness. The interpreter only needs to be fast
19 enough to run small test programs and occasionally to run the compiler
20 on itself. It only needs to be complete enough to test aspects of the
21 design which are developed before the compiler is working, and to run
22 the compiler on itself. Any features not used by the compiler when
23 compiling itself are superfluous. They may be included anyway, but
26 Nonetheless, the interpreter should end up being reasonably complete,
27 and any performance bottlenecks which appear and are easily fixed, will
32 This third version of the interpreter exists to test out some initial
33 ideas relating to types. Particularly it adds arrays (indexed from
34 zero) and simple structures. Basic control flow and variable scoping
35 are already fairly well established, as are basic numerical and
38 Some operators that have only recently been added, and so have not
39 generated all that much experience yet are "and then" and "or else" as
40 short-circuit Boolean operators, and the "if ... else" trinary
41 operator which can select between two expressions based on a third
42 (which appears syntactically in the middle).
44 The "func" clause currently only allows a "main" function to be
45 declared. That will be extended when proper function support is added.
47 An element that is present purely to make a usable language, and
48 without any expectation that they will remain, is the "print" statement
49 which performs simple output.
51 The current scalar types are "number", "Boolean", and "string".
52 Boolean will likely stay in its current form, the other two might, but
53 could just as easily be changed.
57 Versions of the interpreter which obviously do not support a complete
58 language will be named after creeks and streams. This one is Jamison
61 Once we have something reasonably resembling a complete language, the
62 names of rivers will be used.
63 Early versions of the compiler will be named after seas. Major
64 releases of the compiler will be named after oceans. Hopefully I will
65 be finished once I get to the Pacific Ocean release.
69 As well as parsing and executing a program, the interpreter can print
70 out the program from the parsed internal structure. This is useful
71 for validating the parsing.
72 So the main requirements of the interpreter are:
74 - Parse the program, possibly with tracing,
75 - Analyse the parsed program to ensure consistency,
77 - Execute the "main" function in the program, if no parsing or
78 consistency errors were found.
80 This is all performed by a single C program extracted with
83 There will be two formats for printing the program: a default and one
84 that uses bracketing. So a `--bracket` command line option is needed
85 for that. Normally the first code section found is used, however an
86 alternate section can be requested so that a file (such as this one)
87 can contain multiple programs. This is effected with the `--section`
90 This code must be compiled with `-fplan9-extensions` so that anonymous
91 structures can be used.
93 ###### File: oceani.mk
95 myCFLAGS := -Wall -g -fplan9-extensions
96 CFLAGS := $(filter-out $(myCFLAGS),$(CFLAGS)) $(myCFLAGS)
97 myLDLIBS:= libparser.o libscanner.o libmdcode.o -licuuc
98 LDLIBS := $(filter-out $(myLDLIBS),$(LDLIBS)) $(myLDLIBS)
100 all :: $(LDLIBS) oceani
101 oceani.c oceani.h : oceani.mdc parsergen
102 ./parsergen -o oceani --LALR --tag Parser oceani.mdc
103 oceani.mk: oceani.mdc md2c
106 oceani: oceani.o $(LDLIBS)
107 $(CC) $(CFLAGS) -o oceani oceani.o $(LDLIBS)
109 ###### Parser: header
111 struct parse_context;
113 struct parse_context {
114 struct token_config config;
122 #define container_of(ptr, type, member) ({ \
123 const typeof( ((type *)0)->member ) *__mptr = (ptr); \
124 (type *)( (char *)__mptr - offsetof(type,member) );})
126 #define config2context(_conf) container_of(_conf, struct parse_context, \
129 ###### Parser: reduce
130 struct parse_context *c = config2context(config);
138 #include <sys/mman.h>
157 static char Usage[] =
158 "Usage: oceani --trace --print --noexec --brackets --section=SectionName prog.ocn\n";
159 static const struct option long_options[] = {
160 {"trace", 0, NULL, 't'},
161 {"print", 0, NULL, 'p'},
162 {"noexec", 0, NULL, 'n'},
163 {"brackets", 0, NULL, 'b'},
164 {"section", 1, NULL, 's'},
167 const char *options = "tpnbs";
169 static void pr_err(char *msg) // NOTEST
171 fprintf(stderr, "%s\n", msg); // NOTEST
174 int main(int argc, char *argv[])
179 struct section *s = NULL, *ss;
180 char *section = NULL;
181 struct parse_context context = {
183 .ignored = (1 << TK_mark),
184 .number_chars = ".,_+- ",
189 int doprint=0, dotrace=0, doexec=1, brackets=0;
191 while ((opt = getopt_long(argc, argv, options, long_options, NULL))
194 case 't': dotrace=1; break;
195 case 'p': doprint=1; break;
196 case 'n': doexec=0; break;
197 case 'b': brackets=1; break;
198 case 's': section = optarg; break;
199 default: fprintf(stderr, Usage);
203 if (optind >= argc) {
204 fprintf(stderr, "oceani: no input file given\n");
207 fd = open(argv[optind], O_RDONLY);
209 fprintf(stderr, "oceani: cannot open %s\n", argv[optind]);
212 context.file_name = argv[optind];
213 len = lseek(fd, 0, 2);
214 file = mmap(NULL, len, PROT_READ, MAP_SHARED, fd, 0);
215 s = code_extract(file, file+len, pr_err);
217 fprintf(stderr, "oceani: could not find any code in %s\n",
222 ## context initialization
225 for (ss = s; ss; ss = ss->next) {
226 struct text sec = ss->section;
227 if (sec.len == strlen(section) &&
228 strncmp(sec.txt, section, sec.len) == 0)
232 fprintf(stderr, "oceani: cannot find section %s\n",
239 fprintf(stderr, "oceani: no code found in requested section\n"); // NOTEST
240 goto cleanup; // NOTEST
243 parse_oceani(ss->code, &context.config, dotrace ? stderr : NULL);
245 resolve_consts(&context);
246 prepare_types(&context);
247 if (!context.parse_error && !analyse_funcs(&context)) {
248 fprintf(stderr, "oceani: type error in program - not running.\n");
249 context.parse_error += 1;
257 if (doexec && !context.parse_error)
258 interp_main(&context, argc - optind, argv + optind);
261 struct section *t = s->next;
266 // FIXME parser should pop scope even on error
267 while (context.scope_depth > 0)
271 ## free context types
272 ## free context storage
273 exit(context.parse_error ? 1 : 0);
278 The four requirements of parse, analyse, print, interpret apply to
279 each language element individually so that is how most of the code
282 Three of the four are fairly self explanatory. The one that requires
283 a little explanation is the analysis step.
285 The current language design does not require the types of variables to
286 be declared, but they must still have a single type. Different
287 operations impose different requirements on the variables, for example
288 addition requires both arguments to be numeric, and assignment
289 requires the variable on the left to have the same type as the
290 expression on the right.
292 Analysis involves propagating these type requirements around and
293 consequently setting the type of each variable. If any requirements
294 are violated (e.g. a string is compared with a number) or if a
295 variable needs to have two different types, then an error is raised
296 and the program will not run.
298 If the same variable is declared in both branchs of an 'if/else', or
299 in all cases of a 'switch' then the multiple instances may be merged
300 into just one variable if the variable is referenced after the
301 conditional statement. When this happens, the types must naturally be
302 consistent across all the branches. When the variable is not used
303 outside the if, the variables in the different branches are distinct
304 and can be of different types.
306 Undeclared names may only appear in "use" statements and "case" expressions.
307 These names are given a type of "label" and a unique value.
308 This allows them to fill the role of a name in an enumerated type, which
309 is useful for testing the `switch` statement.
311 As we will see, the condition part of a `while` statement can return
312 either a Boolean or some other type. This requires that the expected
313 type that gets passed around comprises a type and a flag to indicate
314 that `Tbool` is also permitted.
316 As there are, as yet, no distinct types that are compatible, there
317 isn't much subtlety in the analysis. When we have distinct number
318 types, this will become more interesting.
322 When analysis discovers an inconsistency it needs to report an error;
323 just refusing to run the code ensures that the error doesn't cascade,
324 but by itself it isn't very useful. A clear understanding of the sort
325 of error message that are useful will help guide the process of
328 At a simplistic level, the only sort of error that type analysis can
329 report is that the type of some construct doesn't match a contextual
330 requirement. For example, in `4 + "hello"` the addition provides a
331 contextual requirement for numbers, but `"hello"` is not a number. In
332 this particular example no further information is needed as the types
333 are obvious from local information. When a variable is involved that
334 isn't the case. It may be helpful to explain why the variable has a
335 particular type, by indicating the location where the type was set,
336 whether by declaration or usage.
338 Using a recursive-descent analysis we can easily detect a problem at
339 multiple locations. In "`hello:= "there"; 4 + hello`" the addition
340 will detect that one argument is not a number and the usage of `hello`
341 will detect that a number was wanted, but not provided. In this
342 (early) version of the language, we will generate error reports at
343 multiple locations, so the use of `hello` will report an error and
344 explain were the value was set, and the addition will report an error
345 and say why numbers are needed. To be able to report locations for
346 errors, each language element will need to record a file location
347 (line and column) and each variable will need to record the language
348 element where its type was set. For now we will assume that each line
349 of an error message indicates one location in the file, and up to 2
350 types. So we provide a `printf`-like function which takes a format, a
351 location (a `struct exec` which has not yet been introduced), and 2
352 types. "`%1`" reports the first type, "`%2`" reports the second. We
353 will need a function to print the location, once we know how that is
354 stored. e As will be explained later, there are sometimes extra rules for
355 type matching and they might affect error messages, we need to pass those
358 As well as type errors, we sometimes need to report problems with
359 tokens, which might be unexpected or might name a type that has not
360 been defined. For these we have `tok_err()` which reports an error
361 with a given token. Each of the error functions sets the flag in the
362 context so indicate that parsing failed.
366 static void fput_loc(struct exec *loc, FILE *f);
367 static void type_err(struct parse_context *c,
368 char *fmt, struct exec *loc,
369 struct type *t1, int rules, struct type *t2);
371 ###### core functions
373 static void type_err(struct parse_context *c,
374 char *fmt, struct exec *loc,
375 struct type *t1, int rules, struct type *t2)
377 fprintf(stderr, "%s:", c->file_name);
378 fput_loc(loc, stderr);
379 for (; *fmt ; fmt++) {
386 case '%': fputc(*fmt, stderr); break; // NOTEST
387 default: fputc('?', stderr); break; // NOTEST
389 type_print(t1, stderr);
392 type_print(t2, stderr);
401 static void tok_err(struct parse_context *c, char *fmt, struct token *t)
403 fprintf(stderr, "%s:%d:%d: %s: %.*s\n", c->file_name, t->line, t->col, fmt,
404 t->txt.len, t->txt.txt);
408 ## Entities: declared and predeclared.
410 There are various "things" that the language and/or the interpreter
411 needs to know about to parse and execute a program. These include
412 types, variables, values, and executable code. These are all lumped
413 together under the term "entities" (calling them "objects" would be
414 confusing) and introduced here. The following section will present the
415 different specific code elements which comprise or manipulate these
420 Executables can be lots of different things. In many cases an
421 executable is just an operation combined with one or two other
422 executables. This allows for expressions and lists etc. Other times an
423 executable is something quite specific like a constant or variable name.
424 So we define a `struct exec` to be a general executable with a type, and
425 a `struct binode` which is a subclass of `exec`, forms a node in a
426 binary tree, and holds an operation. There will be other subclasses,
427 and to access these we need to be able to `cast` the `exec` into the
428 various other types. The first field in any `struct exec` is the type
429 from the `exec_types` enum.
432 #define cast(structname, pointer) ({ \
433 const typeof( ((struct structname *)0)->type) *__mptr = &(pointer)->type; \
434 if (__mptr && *__mptr != X##structname) abort(); \
435 (struct structname *)( (char *)__mptr);})
437 #define new(structname) ({ \
438 struct structname *__ptr = ((struct structname *)calloc(1,sizeof(struct structname))); \
439 __ptr->type = X##structname; \
440 __ptr->line = -1; __ptr->column = -1; \
443 #define new_pos(structname, token) ({ \
444 struct structname *__ptr = ((struct structname *)calloc(1,sizeof(struct structname))); \
445 __ptr->type = X##structname; \
446 __ptr->line = token.line; __ptr->column = token.col; \
455 enum exec_types type;
464 struct exec *left, *right;
469 static int __fput_loc(struct exec *loc, FILE *f)
473 if (loc->line >= 0) {
474 fprintf(f, "%d:%d: ", loc->line, loc->column);
477 if (loc->type == Xbinode)
478 return __fput_loc(cast(binode,loc)->left, f) ||
479 __fput_loc(cast(binode,loc)->right, f); // NOTEST
482 static void fput_loc(struct exec *loc, FILE *f)
484 if (!__fput_loc(loc, f))
485 fprintf(f, "??:??: ");
488 Each different type of `exec` node needs a number of functions defined,
489 a bit like methods. We must be able to free it, print it, analyse it
490 and execute it. Once we have specific `exec` types we will need to
491 parse them too. Let's take this a bit more slowly.
495 The parser generator requires a `free_foo` function for each struct
496 that stores attributes and they will often be `exec`s and subtypes
497 there-of. So we need `free_exec` which can handle all the subtypes,
498 and we need `free_binode`.
502 static void free_binode(struct binode *b)
511 ###### core functions
512 static void free_exec(struct exec *e)
523 static void free_exec(struct exec *e);
525 ###### free exec cases
526 case Xbinode: free_binode(cast(binode, e)); break;
530 Printing an `exec` requires that we know the current indent level for
531 printing line-oriented components. As will become clear later, we
532 also want to know what sort of bracketing to use.
536 static void do_indent(int i, char *str)
543 ###### core functions
544 static void print_binode(struct binode *b, int indent, int bracket)
548 ## print binode cases
552 static void print_exec(struct exec *e, int indent, int bracket)
558 print_binode(cast(binode, e), indent, bracket); break;
563 do_indent(indent, "/* FREE");
564 for (v = e->to_free; v; v = v->next_free) {
565 printf(" %.*s", v->name->name.len, v->name->name.txt);
566 printf("[%d,%d]", v->scope_start, v->scope_end);
567 if (v->frame_pos >= 0)
568 printf("(%d+%d)", v->frame_pos,
569 v->type ? v->type->size:0);
577 static void print_exec(struct exec *e, int indent, int bracket);
581 As discussed, analysis involves propagating type requirements around the
582 program and looking for errors.
584 So `propagate_types` is passed an expected type (being a `struct type`
585 pointer together with some `val_rules` flags) that the `exec` is
586 expected to return, and returns the type that it does return, either of
587 which can be `NULL` signifying "unknown". A `prop_err` flag set is
588 passed by reference. It has `Efail` set when an error is found, and
589 `Eretry` when the type for some element is set via propagation. If it
590 remains unchanged at `0`, then no more propagation is needed.
594 enum val_rules {Rnolabel = 1<<0, Rboolok = 1<<1, Rnoconstant = 1<<2};
595 enum prop_err {Efail = 1<<0, Eretry = 1<<1};
599 if (rules & Rnolabel)
600 fputs(" (labels not permitted)", stderr);
604 static struct type *propagate_types(struct exec *prog, struct parse_context *c, enum prop_err *perr,
605 struct type *type, int rules);
606 ###### core functions
608 static struct type *__propagate_types(struct exec *prog, struct parse_context *c, enum prop_err *perr,
609 struct type *type, int rules)
616 switch (prog->type) {
619 struct binode *b = cast(binode, prog);
621 ## propagate binode cases
625 ## propagate exec cases
630 static struct type *propagate_types(struct exec *prog, struct parse_context *c, enum prop_err *perr,
631 struct type *type, int rules)
633 int pre_err = c->parse_error;
634 struct type *ret = __propagate_types(prog, c, perr, type, rules);
636 if (c->parse_error > pre_err)
643 Interpreting an `exec` doesn't require anything but the `exec`. State
644 is stored in variables and each variable will be directly linked from
645 within the `exec` tree. The exception to this is the `main` function
646 which needs to look at command line arguments. This function will be
647 interpreted separately.
649 Each `exec` can return a value combined with a type in `struct lrval`.
650 The type may be `Tnone` but must be non-NULL. Some `exec`s will return
651 the location of a value, which can be updated, in `lval`. Others will
652 set `lval` to NULL indicating that there is a value of appropriate type
656 static struct value interp_exec(struct parse_context *c, struct exec *e,
657 struct type **typeret);
658 ###### core functions
662 struct value rval, *lval;
665 /* If dest is passed, dtype must give the expected type, and
666 * result can go there, in which case type is returned as NULL.
668 static struct lrval _interp_exec(struct parse_context *c, struct exec *e,
669 struct value *dest, struct type *dtype);
671 static struct value interp_exec(struct parse_context *c, struct exec *e,
672 struct type **typeret)
674 struct lrval ret = _interp_exec(c, e, NULL, NULL);
676 if (!ret.type) abort();
680 dup_value(ret.type, ret.lval, &ret.rval);
684 static struct value *linterp_exec(struct parse_context *c, struct exec *e,
685 struct type **typeret)
687 struct lrval ret = _interp_exec(c, e, NULL, NULL);
689 if (!ret.type) abort();
693 free_value(ret.type, &ret.rval);
697 /* dinterp_exec is used when the destination type is certain and
698 * the value has a place to go.
700 static void dinterp_exec(struct parse_context *c, struct exec *e,
701 struct value *dest, struct type *dtype,
704 struct lrval ret = _interp_exec(c, e, dest, dtype);
708 free_value(dtype, dest);
710 dup_value(dtype, ret.lval, dest);
712 memcpy(dest, &ret.rval, dtype->size);
715 static struct lrval _interp_exec(struct parse_context *c, struct exec *e,
716 struct value *dest, struct type *dtype)
718 /* If the result is copied to dest, ret.type is set to NULL */
720 struct value rv = {}, *lrv = NULL;
723 rvtype = ret.type = Tnone;
733 struct binode *b = cast(binode, e);
734 struct value left, right, *lleft;
735 struct type *ltype, *rtype;
736 ltype = rtype = Tnone;
738 ## interp binode cases
740 free_value(ltype, &left);
741 free_value(rtype, &right);
751 ## interp exec cleanup
757 Values come in a wide range of types, with more likely to be added.
758 Each type needs to be able to print its own values (for convenience at
759 least) as well as to compare two values, at least for equality and
760 possibly for order. For now, values might need to be duplicated and
761 freed, though eventually such manipulations will be better integrated
764 Rather than requiring every numeric type to support all numeric
765 operations (add, multiply, etc), we allow types to be able to present
766 as one of a few standard types: integer, float, and fraction. The
767 existence of these conversion functions eventually enable types to
768 determine if they are compatible with other types, though such types
769 have not yet been implemented.
771 Named type are stored in a simple linked list. Objects of each type are
772 "values" which are often passed around by value.
774 There are both explicitly named types, and anonymous types. Anonymous
775 cannot be accessed by name, but are used internally and have a name
776 which might be reported in error messages.
783 ## value union fields
792 void (*init)(struct type *type, struct value *val);
793 void (*prepare_type)(struct parse_context *c, struct type *type, int parse_time);
794 void (*print)(struct type *type, struct value *val, FILE *f);
795 void (*print_type)(struct type *type, FILE *f);
796 int (*cmp_order)(struct type *t1, struct type *t2,
797 struct value *v1, struct value *v2);
798 int (*cmp_eq)(struct type *t1, struct type *t2,
799 struct value *v1, struct value *v2);
800 void (*dup)(struct type *type, struct value *vold, struct value *vnew);
801 void (*free)(struct type *type, struct value *val);
802 void (*free_type)(struct type *t);
803 long long (*to_int)(struct value *v);
804 double (*to_float)(struct value *v);
805 int (*to_mpq)(mpq_t *q, struct value *v);
814 struct type *typelist;
821 static struct type *find_type(struct parse_context *c, struct text s)
823 struct type *t = c->typelist;
825 while (t && (t->anon ||
826 text_cmp(t->name, s) != 0))
831 static struct type *_add_type(struct parse_context *c, struct text s,
832 struct type *proto, int anon)
836 n = calloc(1, sizeof(*n));
840 n->next = c->typelist;
845 static struct type *add_type(struct parse_context *c, struct text s,
848 return _add_type(c, s, proto, 0);
851 static struct type *add_anon_type(struct parse_context *c,
852 struct type *proto, char *name, ...)
858 vasprintf(&t.txt, name, ap);
860 t.len = strlen(name);
861 return _add_type(c, t, proto, 1);
864 static void free_type(struct type *t)
866 /* The type is always a reference to something in the
867 * context, so we don't need to free anything.
871 static void free_value(struct type *type, struct value *v)
875 memset(v, 0x5a, type->size);
879 static void type_print(struct type *type, FILE *f)
882 fputs("*unknown*type*", f); // NOTEST
883 else if (type->name.len && !type->anon)
884 fprintf(f, "%.*s", type->name.len, type->name.txt);
885 else if (type->print_type)
886 type->print_type(type, f);
888 fputs("*invalid*type*", f);
891 static void val_init(struct type *type, struct value *val)
893 if (type && type->init)
894 type->init(type, val);
897 static void dup_value(struct type *type,
898 struct value *vold, struct value *vnew)
900 if (type && type->dup)
901 type->dup(type, vold, vnew);
904 static int value_cmp(struct type *tl, struct type *tr,
905 struct value *left, struct value *right)
907 if (tl && tl->cmp_order)
908 return tl->cmp_order(tl, tr, left, right);
909 if (tl && tl->cmp_eq) // NOTEST
910 return tl->cmp_eq(tl, tr, left, right); // NOTEST
914 static void print_value(struct type *type, struct value *v, FILE *f)
916 if (type && type->print)
917 type->print(type, v, f);
919 fprintf(f, "*Unknown*"); // NOTEST
922 static void prepare_types(struct parse_context *c)
926 for (t = c->typelist; t; t = t->next)
928 t->prepare_type(c, t, 1);
933 static void free_value(struct type *type, struct value *v);
934 static int type_compat(struct type *require, struct type *have, int rules);
935 static void type_print(struct type *type, FILE *f);
936 static void val_init(struct type *type, struct value *v);
937 static void dup_value(struct type *type,
938 struct value *vold, struct value *vnew);
939 static int value_cmp(struct type *tl, struct type *tr,
940 struct value *left, struct value *right);
941 static void print_value(struct type *type, struct value *v, FILE *f);
943 ###### free context types
945 while (context.typelist) {
946 struct type *t = context.typelist;
948 context.typelist = t->next;
956 Type can be specified for local variables, for fields in a structure,
957 for formal parameters to functions, and possibly elsewhere. Different
958 rules may apply in different contexts. As a minimum, a named type may
959 always be used. Currently the type of a formal parameter can be
960 different from types in other contexts, so we have a separate grammar
966 Type -> IDENTIFIER ${
967 $0 = find_type(c, $1.txt);
970 "error: undefined type", &$1);
977 FormalType -> Type ${ $0 = $<1; }$
978 ## formal type grammar
982 Values of the base types can be numbers, which we represent as
983 multi-precision fractions, strings, Booleans and labels. When
984 analysing the program we also need to allow for places where no value
985 is meaningful (type `Tnone`) and where we don't know what type to
986 expect yet (type is `NULL`).
988 Values are never shared, they are always copied when used, and freed
989 when no longer needed.
991 When propagating type information around the program, we need to
992 determine if two types are compatible, where type `NULL` is compatible
993 with anything. There are two special cases with type compatibility,
994 both related to the Conditional Statement which will be described
995 later. In some cases a Boolean can be accepted as well as some other
996 primary type, and in others any type is acceptable except a label (`Vlabel`).
997 A separate function encoding these cases will simplify some code later.
999 ###### type functions
1001 int (*compat)(struct type *this, struct type *other);
1003 ###### ast functions
1005 static int type_compat(struct type *require, struct type *have, int rules)
1007 if ((rules & Rboolok) && have == Tbool)
1009 if ((rules & Rnolabel) && have == Tlabel)
1011 if (!require || !have)
1014 if (require->compat)
1015 return require->compat(require, have);
1017 return require == have;
1022 #include "parse_string.h"
1023 #include "parse_number.h"
1026 myLDLIBS := libnumber.o libstring.o -lgmp
1027 LDLIBS := $(filter-out $(myLDLIBS),$(LDLIBS)) $(myLDLIBS)
1029 ###### type union fields
1030 enum vtype {Vnone, Vstr, Vnum, Vbool, Vlabel} vtype;
1032 ###### value union fields
1038 ###### ast functions
1039 static void _free_value(struct type *type, struct value *v)
1043 switch (type->vtype) {
1045 case Vstr: free(v->str.txt); break;
1046 case Vnum: mpq_clear(v->num); break;
1052 ###### value functions
1054 static void _val_init(struct type *type, struct value *val)
1056 switch(type->vtype) {
1057 case Vnone: // NOTEST
1060 mpq_init(val->num); break;
1062 val->str.txt = malloc(1);
1074 static void _dup_value(struct type *type,
1075 struct value *vold, struct value *vnew)
1077 switch (type->vtype) {
1078 case Vnone: // NOTEST
1081 vnew->label = vold->label;
1084 vnew->bool = vold->bool;
1087 mpq_init(vnew->num);
1088 mpq_set(vnew->num, vold->num);
1091 vnew->str.len = vold->str.len;
1092 vnew->str.txt = malloc(vnew->str.len);
1093 memcpy(vnew->str.txt, vold->str.txt, vnew->str.len);
1098 static int _value_cmp(struct type *tl, struct type *tr,
1099 struct value *left, struct value *right)
1103 return tl - tr; // NOTEST
1104 switch (tl->vtype) {
1105 case Vlabel: cmp = left->label == right->label ? 0 : 1; break;
1106 case Vnum: cmp = mpq_cmp(left->num, right->num); break;
1107 case Vstr: cmp = text_cmp(left->str, right->str); break;
1108 case Vbool: cmp = left->bool - right->bool; break;
1109 case Vnone: cmp = 0; // NOTEST
1114 static void _print_value(struct type *type, struct value *v, FILE *f)
1116 switch (type->vtype) {
1117 case Vnone: // NOTEST
1118 fprintf(f, "*no-value*"); break; // NOTEST
1119 case Vlabel: // NOTEST
1120 fprintf(f, "*label-%p*", v->label); break; // NOTEST
1122 fprintf(f, "%.*s", v->str.len, v->str.txt); break;
1124 fprintf(f, "%s", v->bool ? "True":"False"); break;
1129 mpf_set_q(fl, v->num);
1130 gmp_fprintf(f, "%.10Fg", fl);
1137 static void _free_value(struct type *type, struct value *v);
1139 static struct type base_prototype = {
1141 .print = _print_value,
1142 .cmp_order = _value_cmp,
1143 .cmp_eq = _value_cmp,
1145 .free = _free_value,
1148 static struct type *Tbool, *Tstr, *Tnum, *Tnone, *Tlabel;
1150 ###### ast functions
1151 static struct type *add_base_type(struct parse_context *c, char *n,
1152 enum vtype vt, int size)
1154 struct text txt = { n, strlen(n) };
1157 t = add_type(c, txt, &base_prototype);
1160 t->align = size > sizeof(void*) ? sizeof(void*) : size;
1161 if (t->size & (t->align - 1))
1162 t->size = (t->size | (t->align - 1)) + 1; // NOTEST
1166 ###### context initialization
1168 Tbool = add_base_type(&context, "Boolean", Vbool, sizeof(char));
1169 Tstr = add_base_type(&context, "string", Vstr, sizeof(struct text));
1170 Tnum = add_base_type(&context, "number", Vnum, sizeof(mpq_t));
1171 Tnone = add_base_type(&context, "none", Vnone, 0);
1172 Tlabel = add_base_type(&context, "label", Vlabel, sizeof(void*));
1176 We have already met values as separate objects. When manifest constants
1177 appear in the program text, that must result in an executable which has
1178 a constant value. So the `val` structure embeds a value in an
1191 ###### ast functions
1192 struct val *new_val(struct type *T, struct token tk)
1194 struct val *v = new_pos(val, tk);
1205 $0 = new_val(Tbool, $1);
1209 $0 = new_val(Tbool, $1);
1214 $0 = new_val(Tnum, $1);
1215 if (number_parse($0->val.num, tail, $1.txt) == 0)
1216 mpq_init($0->val.num); // UNTESTED
1218 tok_err(c, "error: unsupported number suffix",
1223 $0 = new_val(Tstr, $1);
1224 string_parse(&$1, '\\', &$0->val.str, tail);
1226 tok_err(c, "error: unsupported string suffix",
1231 $0 = new_val(Tstr, $1);
1232 string_parse(&$1, '\\', &$0->val.str, tail);
1234 tok_err(c, "error: unsupported string suffix",
1238 ###### print exec cases
1241 struct val *v = cast(val, e);
1242 if (v->vtype == Tstr)
1244 // FIXME how to ensure numbers have same precision.
1245 print_value(v->vtype, &v->val, stdout);
1246 if (v->vtype == Tstr)
1251 ###### propagate exec cases
1254 struct val *val = cast(val, prog);
1255 if (!type_compat(type, val->vtype, rules))
1256 type_err(c, "error: expected %1%r found %2",
1257 prog, type, rules, val->vtype);
1261 ###### interp exec cases
1263 rvtype = cast(val, e)->vtype;
1264 dup_value(rvtype, &cast(val, e)->val, &rv);
1267 ###### ast functions
1268 static void free_val(struct val *v)
1271 free_value(v->vtype, &v->val);
1275 ###### free exec cases
1276 case Xval: free_val(cast(val, e)); break;
1278 ###### ast functions
1279 // Move all nodes from 'b' to 'rv', reversing their order.
1280 // In 'b' 'left' is a list, and 'right' is the last node.
1281 // In 'rv', left' is the first node and 'right' is a list.
1282 static struct binode *reorder_bilist(struct binode *b)
1284 struct binode *rv = NULL;
1287 struct exec *t = b->right;
1291 b = cast(binode, b->left);
1301 Variables are scoped named values. We store the names in a linked list
1302 of "bindings" sorted in lexical order, and use sequential search and
1309 struct binding *next; // in lexical order
1313 This linked list is stored in the parse context so that "reduce"
1314 functions can find or add variables, and so the analysis phase can
1315 ensure that every variable gets a type.
1317 ###### parse context
1319 struct binding *varlist; // In lexical order
1321 ###### ast functions
1323 static struct binding *find_binding(struct parse_context *c, struct text s)
1325 struct binding **l = &c->varlist;
1330 (cmp = text_cmp((*l)->name, s)) < 0)
1334 n = calloc(1, sizeof(*n));
1341 Each name can be linked to multiple variables defined in different
1342 scopes. Each scope starts where the name is declared and continues
1343 until the end of the containing code block. Scopes of a given name
1344 cannot nest, so a declaration while a name is in-scope is an error.
1346 ###### binding fields
1347 struct variable *var;
1351 struct variable *previous;
1353 struct binding *name;
1354 struct exec *where_decl;// where name was declared
1355 struct exec *where_set; // where type was set
1359 When a scope closes, the values of the variables might need to be freed.
1360 This happens in the context of some `struct exec` and each `exec` will
1361 need to know which variables need to be freed when it completes.
1364 struct variable *to_free;
1366 ####### variable fields
1367 struct exec *cleanup_exec;
1368 struct variable *next_free;
1370 ####### interp exec cleanup
1373 for (v = e->to_free; v; v = v->next_free) {
1374 struct value *val = var_value(c, v);
1375 free_value(v->type, val);
1379 ###### ast functions
1380 static void variable_unlink_exec(struct variable *v)
1382 struct variable **vp;
1383 if (!v->cleanup_exec)
1385 for (vp = &v->cleanup_exec->to_free;
1386 *vp; vp = &(*vp)->next_free) {
1390 v->cleanup_exec = NULL;
1395 While the naming seems strange, we include local constants in the
1396 definition of variables. A name declared `var := value` can
1397 subsequently be changed, but a name declared `var ::= value` cannot -
1400 ###### variable fields
1403 Scopes in parallel branches can be partially merged. More
1404 specifically, if a given name is declared in both branches of an
1405 if/else then its scope is a candidate for merging. Similarly if
1406 every branch of an exhaustive switch (e.g. has an "else" clause)
1407 declares a given name, then the scopes from the branches are
1408 candidates for merging.
1410 Note that names declared inside a loop (which is only parallel to
1411 itself) are never visible after the loop. Similarly names defined in
1412 scopes which are not parallel, such as those started by `for` and
1413 `switch`, are never visible after the scope. Only variables defined in
1414 both `then` and `else` (including the implicit then after an `if`, and
1415 excluding `then` used with `for`) and in all `case`s and `else` of a
1416 `switch` or `while` can be visible beyond the `if`/`switch`/`while`.
1418 Labels, which are a bit like variables, follow different rules.
1419 Labels are not explicitly declared, but if an undeclared name appears
1420 in a context where a label is legal, that effectively declares the
1421 name as a label. The declaration remains in force (or in scope) at
1422 least to the end of the immediately containing block and conditionally
1423 in any larger containing block which does not declare the name in some
1424 other way. Importantly, the conditional scope extension happens even
1425 if the label is only used in one parallel branch of a conditional --
1426 when used in one branch it is treated as having been declared in all
1429 Merge candidates are tentatively visible beyond the end of the
1430 branching statement which creates them. If the name is used, the
1431 merge is affirmed and they become a single variable visible at the
1432 outer layer. If not - if it is redeclared first - the merge lapses.
1434 To track scopes we have an extra stack, implemented as a linked list,
1435 which roughly parallels the parse stack and which is used exclusively
1436 for scoping. When a new scope is opened, a new frame is pushed and
1437 the child-count of the parent frame is incremented. This child-count
1438 is used to distinguish between the first of a set of parallel scopes,
1439 in which declared variables must not be in scope, and subsequent
1440 branches, whether they may already be conditionally scoped.
1442 We need a total ordering of scopes so we can easily compare to variables
1443 to see if they are concurrently in scope. To achieve this we record a
1444 `scope_count` which is actually a count of both beginnings and endings
1445 of scopes. Then each variable has a record of the scope count where it
1446 enters scope, and where it leaves.
1448 To push a new frame *before* any code in the frame is parsed, we need a
1449 grammar reduction. This is most easily achieved with a grammar
1450 element which derives the empty string, and creates the new scope when
1451 it is recognised. This can be placed, for example, between a keyword
1452 like "if" and the code following it.
1456 struct scope *parent;
1460 ###### parse context
1463 struct scope *scope_stack;
1465 ###### variable fields
1466 int scope_start, scope_end;
1468 ###### ast functions
1469 static void scope_pop(struct parse_context *c)
1471 struct scope *s = c->scope_stack;
1473 c->scope_stack = s->parent;
1475 c->scope_depth -= 1;
1476 c->scope_count += 1;
1479 static void scope_push(struct parse_context *c)
1481 struct scope *s = calloc(1, sizeof(*s));
1483 c->scope_stack->child_count += 1;
1484 s->parent = c->scope_stack;
1486 c->scope_depth += 1;
1487 c->scope_count += 1;
1493 OpenScope -> ${ scope_push(c); }$
1495 Each variable records a scope depth and is in one of four states:
1497 - "in scope". This is the case between the declaration of the
1498 variable and the end of the containing block, and also between
1499 the usage with affirms a merge and the end of that block.
1501 The scope depth is not greater than the current parse context scope
1502 nest depth. When the block of that depth closes, the state will
1503 change. To achieve this, all "in scope" variables are linked
1504 together as a stack in nesting order.
1506 - "pending". The "in scope" block has closed, but other parallel
1507 scopes are still being processed. So far, every parallel block at
1508 the same level that has closed has declared the name.
1510 The scope depth is the depth of the last parallel block that
1511 enclosed the declaration, and that has closed.
1513 - "conditionally in scope". The "in scope" block and all parallel
1514 scopes have closed, and no further mention of the name has been seen.
1515 This state includes a secondary nest depth (`min_depth`) which records
1516 the outermost scope seen since the variable became conditionally in
1517 scope. If a use of the name is found, the variable becomes "in scope"
1518 and that secondary depth becomes the recorded scope depth. If the
1519 name is declared as a new variable, the old variable becomes "out of
1520 scope" and the recorded scope depth stays unchanged.
1522 - "out of scope". The variable is neither in scope nor conditionally
1523 in scope. It is permanently out of scope now and can be removed from
1524 the "in scope" stack. When a variable becomes out-of-scope it is
1525 moved to a separate list (`out_scope`) of variables which have fully
1526 known scope. This will be used at the end of each function to assign
1527 each variable a place in the stack frame.
1529 ###### variable fields
1530 int depth, min_depth;
1531 enum { OutScope, PendingScope, CondScope, InScope } scope;
1532 struct variable *in_scope;
1534 ###### parse context
1536 struct variable *in_scope;
1537 struct variable *out_scope;
1539 All variables with the same name are linked together using the
1540 'previous' link. Those variable that have been affirmatively merged all
1541 have a 'merged' pointer that points to one primary variable - the most
1542 recently declared instance. When merging variables, we need to also
1543 adjust the 'merged' pointer on any other variables that had previously
1544 been merged with the one that will no longer be primary.
1546 A variable that is no longer the most recent instance of a name may
1547 still have "pending" scope, if it might still be merged with most
1548 recent instance. These variables don't really belong in the
1549 "in_scope" list, but are not immediately removed when a new instance
1550 is found. Instead, they are detected and ignored when considering the
1551 list of in_scope names.
1553 The storage of the value of a variable will be described later. For now
1554 we just need to know that when a variable goes out of scope, it might
1555 need to be freed. For this we need to be able to find it, so assume that
1556 `var_value()` will provide that.
1558 ###### variable fields
1559 struct variable *merged;
1561 ###### ast functions
1563 static void variable_merge(struct variable *primary, struct variable *secondary)
1567 primary = primary->merged;
1569 for (v = primary->previous; v; v=v->previous)
1570 if (v == secondary || v == secondary->merged ||
1571 v->merged == secondary ||
1572 v->merged == secondary->merged) {
1573 v->scope = OutScope;
1574 v->merged = primary;
1575 if (v->scope_start < primary->scope_start)
1576 primary->scope_start = v->scope_start;
1577 if (v->scope_end > primary->scope_end)
1578 primary->scope_end = v->scope_end; // NOTEST
1579 variable_unlink_exec(v);
1583 ###### forward decls
1584 static struct value *var_value(struct parse_context *c, struct variable *v);
1586 ###### free global vars
1588 while (context.varlist) {
1589 struct binding *b = context.varlist;
1590 struct variable *v = b->var;
1591 context.varlist = b->next;
1594 struct variable *next = v->previous;
1596 if (v->global && v->frame_pos >= 0) {
1597 free_value(v->type, var_value(&context, v));
1598 if (v->depth == 0 && v->type->free == function_free)
1599 // This is a function constant
1600 free_exec(v->where_decl);
1607 #### Manipulating Bindings
1609 When a name is conditionally visible, a new declaration discards the old
1610 binding - the condition lapses. Similarly when we reach the end of a
1611 function (outermost non-global scope) any conditional scope must lapse.
1612 Conversely a usage of the name affirms the visibility and extends it to
1613 the end of the containing block - i.e. the block that contains both the
1614 original declaration and the latest usage. This is determined from
1615 `min_depth`. When a conditionally visible variable gets affirmed like
1616 this, it is also merged with other conditionally visible variables with
1619 When we parse a variable declaration we either report an error if the
1620 name is currently bound, or create a new variable at the current nest
1621 depth if the name is unbound or bound to a conditionally scoped or
1622 pending-scope variable. If the previous variable was conditionally
1623 scoped, it and its homonyms becomes out-of-scope.
1625 When we parse a variable reference (including non-declarative assignment
1626 "foo = bar") we report an error if the name is not bound or is bound to
1627 a pending-scope variable; update the scope if the name is bound to a
1628 conditionally scoped variable; or just proceed normally if the named
1629 variable is in scope.
1631 When we exit a scope, any variables bound at this level are either
1632 marked out of scope or pending-scoped, depending on whether the scope
1633 was sequential or parallel. Here a "parallel" scope means the "then"
1634 or "else" part of a conditional, or any "case" or "else" branch of a
1635 switch. Other scopes are "sequential".
1637 When exiting a parallel scope we check if there are any variables that
1638 were previously pending and are still visible. If there are, then
1639 they weren't redeclared in the most recent scope, so they cannot be
1640 merged and must become out-of-scope. If it is not the first of
1641 parallel scopes (based on `child_count`), we check that there was a
1642 previous binding that is still pending-scope. If there isn't, the new
1643 variable must now be out-of-scope.
1645 When exiting a sequential scope that immediately enclosed parallel
1646 scopes, we need to resolve any pending-scope variables. If there was
1647 no `else` clause, and we cannot determine that the `switch` was exhaustive,
1648 we need to mark all pending-scope variable as out-of-scope. Otherwise
1649 all pending-scope variables become conditionally scoped.
1652 enum closetype { CloseSequential, CloseFunction, CloseParallel, CloseElse };
1654 ###### ast functions
1656 static struct variable *var_decl(struct parse_context *c, struct text s)
1658 struct binding *b = find_binding(c, s);
1659 struct variable *v = b->var;
1661 switch (v ? v->scope : OutScope) {
1663 /* Caller will report the error */
1667 v && v->scope == CondScope;
1669 v->scope = OutScope;
1673 v = calloc(1, sizeof(*v));
1674 v->previous = b->var;
1678 v->min_depth = v->depth = c->scope_depth;
1680 v->in_scope = c->in_scope;
1681 v->scope_start = c->scope_count;
1687 static struct variable *var_ref(struct parse_context *c, struct text s)
1689 struct binding *b = find_binding(c, s);
1690 struct variable *v = b->var;
1691 struct variable *v2;
1693 switch (v ? v->scope : OutScope) {
1696 /* Caller will report the error */
1699 /* All CondScope variables of this name need to be merged
1700 * and become InScope
1702 v->depth = v->min_depth;
1704 for (v2 = v->previous;
1705 v2 && v2->scope == CondScope;
1707 variable_merge(v, v2);
1715 static int var_refile(struct parse_context *c, struct variable *v)
1717 /* Variable just went out of scope. Add it to the out_scope
1718 * list, sorted by ->scope_start
1720 struct variable **vp = &c->out_scope;
1721 while ((*vp) && (*vp)->scope_start < v->scope_start)
1722 vp = &(*vp)->in_scope;
1728 static void var_block_close(struct parse_context *c, enum closetype ct,
1731 /* Close off all variables that are in_scope.
1732 * Some variables in c->scope may already be not-in-scope,
1733 * such as when a PendingScope variable is hidden by a new
1734 * variable with the same name.
1735 * So we check for v->name->var != v and drop them.
1736 * If we choose to make a variable OutScope, we drop it
1739 struct variable *v, **vp, *v2;
1742 for (vp = &c->in_scope;
1743 (v = *vp) && v->min_depth > c->scope_depth;
1744 (v->scope == OutScope || v->name->var != v)
1745 ? (*vp = v->in_scope, var_refile(c, v))
1746 : ( vp = &v->in_scope, 0)) {
1747 v->min_depth = c->scope_depth;
1748 if (v->name->var != v)
1749 /* This is still in scope, but we haven't just
1753 v->min_depth = c->scope_depth;
1754 if (v->scope == InScope)
1755 v->scope_end = c->scope_count;
1756 if (v->scope == InScope && e && !v->global) {
1757 /* This variable gets cleaned up when 'e' finishes */
1758 variable_unlink_exec(v);
1759 v->cleanup_exec = e;
1760 v->next_free = e->to_free;
1765 case CloseParallel: /* handle PendingScope */
1769 if (c->scope_stack->child_count == 1)
1770 /* first among parallel branches */
1771 v->scope = PendingScope;
1772 else if (v->previous &&
1773 v->previous->scope == PendingScope)
1774 /* all previous branches used name */
1775 v->scope = PendingScope;
1776 else if (v->type == Tlabel)
1777 /* Labels remain pending even when not used */
1778 v->scope = PendingScope; // UNTESTED
1780 v->scope = OutScope;
1781 if (ct == CloseElse) {
1782 /* All Pending variables with this name
1783 * are now Conditional */
1785 v2 && v2->scope == PendingScope;
1787 v2->scope = CondScope;
1791 /* Not possible as it would require
1792 * parallel scope to be nested immediately
1793 * in a parallel scope, and that never
1797 /* Not possible as we already tested for
1804 if (v->scope == CondScope)
1805 /* Condition cannot continue past end of function */
1808 case CloseSequential:
1809 if (v->type == Tlabel)
1810 v->scope = PendingScope;
1813 v->scope = OutScope;
1816 /* There was no 'else', so we can only become
1817 * conditional if we know the cases were exhaustive,
1818 * and that doesn't mean anything yet.
1819 * So only labels become conditional..
1822 v2 && v2->scope == PendingScope;
1824 if (v2->type == Tlabel)
1825 v2->scope = CondScope;
1827 v2->scope = OutScope;
1830 case OutScope: break;
1839 The value of a variable is store separately from the variable, on an
1840 analogue of a stack frame. There are (currently) two frames that can be
1841 active. A global frame which currently only stores constants, and a
1842 stacked frame which stores local variables. Each variable knows if it
1843 is global or not, and what its index into the frame is.
1845 Values in the global frame are known immediately they are relevant, so
1846 the frame needs to be reallocated as it grows so it can store those
1847 values. The local frame doesn't get values until the interpreted phase
1848 is started, so there is no need to allocate until the size is known.
1850 We initialize the `frame_pos` to an impossible value, so that we can
1851 tell if it was set or not later.
1853 ###### variable fields
1857 ###### variable init
1860 ###### parse context
1862 short global_size, global_alloc;
1864 void *global, *local;
1866 ###### forward decls
1867 static struct value *global_alloc(struct parse_context *c, struct type *t,
1868 struct variable *v, struct value *init);
1870 ###### ast functions
1872 static struct value *var_value(struct parse_context *c, struct variable *v)
1875 if (!c->local || !v->type)
1877 if (v->frame_pos + v->type->size > c->local_size) {
1878 printf("INVALID frame_pos\n"); // NOTEST
1881 return c->local + v->frame_pos;
1883 if (c->global_size > c->global_alloc) {
1884 int old = c->global_alloc;
1885 c->global_alloc = (c->global_size | 1023) + 1024;
1886 c->global = realloc(c->global, c->global_alloc);
1887 memset(c->global + old, 0, c->global_alloc - old);
1889 return c->global + v->frame_pos;
1892 static struct value *global_alloc(struct parse_context *c, struct type *t,
1893 struct variable *v, struct value *init)
1896 struct variable scratch;
1898 if (t->prepare_type)
1899 t->prepare_type(c, t, 1); // NOTEST
1901 if (c->global_size & (t->align - 1))
1902 c->global_size = (c->global_size + t->align) & ~(t->align-1); // NOTEST
1907 v->frame_pos = c->global_size;
1909 c->global_size += v->type->size;
1910 ret = var_value(c, v);
1912 memcpy(ret, init, t->size);
1918 As global values are found -- struct field initializers, labels etc --
1919 `global_alloc()` is called to record the value in the global frame.
1921 When the program is fully parsed, each function is analysed, we need to
1922 walk the list of variables local to that function and assign them an
1923 offset in the stack frame. For this we have `scope_finalize()`.
1925 We keep the stack from dense by re-using space for between variables
1926 that are not in scope at the same time. The `out_scope` list is sorted
1927 by `scope_start` and as we process a varible, we move it to an FIFO
1928 stack. For each variable we consider, we first discard any from the
1929 stack anything that went out of scope before the new variable came in.
1930 Then we place the new variable just after the one at the top of the
1933 ###### ast functions
1935 static void scope_finalize(struct parse_context *c, struct type *ft)
1937 int size = ft->function.local_size;
1938 struct variable *next = ft->function.scope;
1939 struct variable *done = NULL;
1942 struct variable *v = next;
1943 struct type *t = v->type;
1950 if (v->frame_pos >= 0)
1952 while (done && done->scope_end < v->scope_start)
1953 done = done->in_scope;
1955 pos = done->frame_pos + done->type->size;
1957 pos = ft->function.local_size;
1958 if (pos & (t->align - 1))
1959 pos = (pos + t->align) & ~(t->align-1);
1961 if (size < pos + v->type->size)
1962 size = pos + v->type->size;
1966 c->out_scope = NULL;
1967 ft->function.local_size = size;
1970 ###### free context storage
1971 free(context.global);
1973 #### Variables as executables
1975 Just as we used a `val` to wrap a value into an `exec`, we similarly
1976 need a `var` to wrap a `variable` into an exec. While each `val`
1977 contained a copy of the value, each `var` holds a link to the variable
1978 because it really is the same variable no matter where it appears.
1979 When a variable is used, we need to remember to follow the `->merged`
1980 link to find the primary instance.
1982 When a variable is declared, it may or may not be given an explicit
1983 type. We need to record which so that we can report the parsed code
1992 struct variable *var;
1995 ###### variable fields
2003 VariableDecl -> IDENTIFIER : ${ {
2004 struct variable *v = var_decl(c, $1.txt);
2005 $0 = new_pos(var, $1);
2010 v = var_ref(c, $1.txt);
2012 type_err(c, "error: variable '%v' redeclared",
2014 type_err(c, "info: this is where '%v' was first declared",
2015 v->where_decl, NULL, 0, NULL);
2018 | IDENTIFIER :: ${ {
2019 struct variable *v = var_decl(c, $1.txt);
2020 $0 = new_pos(var, $1);
2026 v = var_ref(c, $1.txt);
2028 type_err(c, "error: variable '%v' redeclared",
2030 type_err(c, "info: this is where '%v' was first declared",
2031 v->where_decl, NULL, 0, NULL);
2034 | IDENTIFIER : Type ${ {
2035 struct variable *v = var_decl(c, $1.txt);
2036 $0 = new_pos(var, $1);
2042 v->explicit_type = 1;
2044 v = var_ref(c, $1.txt);
2046 type_err(c, "error: variable '%v' redeclared",
2048 type_err(c, "info: this is where '%v' was first declared",
2049 v->where_decl, NULL, 0, NULL);
2052 | IDENTIFIER :: Type ${ {
2053 struct variable *v = var_decl(c, $1.txt);
2054 $0 = new_pos(var, $1);
2061 v->explicit_type = 1;
2063 v = var_ref(c, $1.txt);
2065 type_err(c, "error: variable '%v' redeclared",
2067 type_err(c, "info: this is where '%v' was first declared",
2068 v->where_decl, NULL, 0, NULL);
2073 Variable -> IDENTIFIER ${ {
2074 struct variable *v = var_ref(c, $1.txt);
2075 $0 = new_pos(var, $1);
2077 /* This might be a label - allocate a var just in case */
2078 v = var_decl(c, $1.txt);
2085 cast(var, $0)->var = v;
2088 ###### print exec cases
2091 struct var *v = cast(var, e);
2093 struct binding *b = v->var->name;
2094 printf("%.*s", b->name.len, b->name.txt);
2101 if (loc && loc->type == Xvar) {
2102 struct var *v = cast(var, loc);
2104 struct binding *b = v->var->name;
2105 fprintf(stderr, "%.*s", b->name.len, b->name.txt);
2107 fputs("???", stderr); // NOTEST
2109 fputs("NOTVAR", stderr);
2112 ###### propagate exec cases
2116 struct var *var = cast(var, prog);
2117 struct variable *v = var->var;
2119 type_err(c, "%d:BUG: no variable!!", prog, NULL, 0, NULL); // NOTEST
2120 return Tnone; // NOTEST
2123 if (v->constant && (rules & Rnoconstant)) {
2124 type_err(c, "error: Cannot assign to a constant: %v",
2125 prog, NULL, 0, NULL);
2126 type_err(c, "info: name was defined as a constant here",
2127 v->where_decl, NULL, 0, NULL);
2130 if (v->type == Tnone && v->where_decl == prog)
2131 type_err(c, "error: variable used but not declared: %v",
2132 prog, NULL, 0, NULL);
2133 if (v->type == NULL) {
2134 if (type && !(*perr & Efail)) {
2136 v->where_set = prog;
2141 if (!type_compat(type, v->type, rules)) {
2142 type_err(c, "error: expected %1%r but variable '%v' is %2", prog,
2143 type, rules, v->type);
2144 type_err(c, "info: this is where '%v' was set to %1", v->where_set,
2145 v->type, rules, NULL);
2152 ###### interp exec cases
2155 struct var *var = cast(var, e);
2156 struct variable *v = var->var;
2159 lrv = var_value(c, v);
2164 ###### ast functions
2166 static void free_var(struct var *v)
2171 ###### free exec cases
2172 case Xvar: free_var(cast(var, e)); break;
2177 Now that we have the shape of the interpreter in place we can add some
2178 complex types and connected them in to the data structures and the
2179 different phases of parse, analyse, print, interpret.
2181 Being "complex" the language will naturally have syntax to access
2182 specifics of objects of these types. These will fit into the grammar as
2183 "Terms" which are the things that are combined with various operators to
2184 form "Expression". Where a Term is formed by some operation on another
2185 Term, the subordinate Term will always come first, so for example a
2186 member of an array will be expressed as the Term for the array followed
2187 by an index in square brackets. The strict rule of using postfix
2188 operations makes precedence irrelevant within terms. To provide a place
2189 to put the grammar for each terms of each type, we will start out by
2190 introducing the "Term" grammar production, with contains at least a
2191 simple "Value" (to be explained later).
2195 Term -> Value ${ $0 = $<1; }$
2196 | Variable ${ $0 = $<1; }$
2199 Thus far the complex types we have are arrays and structs.
2203 Arrays can be declared by giving a size and a type, as `[size]type' so
2204 `freq:[26]number` declares `freq` to be an array of 26 numbers. The
2205 size can be either a literal number, or a named constant. Some day an
2206 arbitrary expression will be supported.
2208 As a formal parameter to a function, the array can be declared with a
2209 new variable as the size: `name:[size::number]string`. The `size`
2210 variable is set to the size of the array and must be a constant. As
2211 `number` is the only supported type, it can be left out:
2212 `name:[size::]string`.
2214 Arrays cannot be assigned. When pointers are introduced we will also
2215 introduce array slices which can refer to part or all of an array -
2216 the assignment syntax will create a slice. For now, an array can only
2217 ever be referenced by the name it is declared with. It is likely that
2218 a "`copy`" primitive will eventually be define which can be used to
2219 make a copy of an array with controllable recursive depth.
2221 For now we have two sorts of array, those with fixed size either because
2222 it is given as a literal number or because it is a struct member (which
2223 cannot have a runtime-changing size), and those with a size that is
2224 determined at runtime - local variables with a const size. The former
2225 have their size calculated at parse time, the latter at run time.
2227 For the latter type, the `size` field of the type is the size of a
2228 pointer, and the array is reallocated every time it comes into scope.
2230 We differentiate struct fields with a const size from local variables
2231 with a const size by whether they are prepared at parse time or not.
2233 ###### type union fields
2236 int unspec; // size is unspecified - vsize must be set.
2239 struct variable *vsize;
2240 struct type *member;
2243 ###### value union fields
2244 void *array; // used if not static_size
2246 ###### value functions
2248 static void array_prepare_type(struct parse_context *c, struct type *type,
2251 struct value *vsize;
2253 if (type->array.static_size)
2255 if (type->array.unspec && parse_time)
2258 if (type->array.vsize) {
2259 vsize = var_value(c, type->array.vsize);
2263 mpz_tdiv_q(q, mpq_numref(vsize->num), mpq_denref(vsize->num));
2264 type->array.size = mpz_get_si(q);
2268 if (parse_time && type->array.member->size) {
2269 type->array.static_size = 1;
2270 type->size = type->array.size * type->array.member->size;
2271 type->align = type->array.member->align;
2275 static void array_init(struct type *type, struct value *val)
2278 void *ptr = val->ptr;
2282 if (!type->array.static_size) {
2283 val->array = calloc(type->array.size,
2284 type->array.member->size);
2287 for (i = 0; i < type->array.size; i++) {
2289 v = (void*)ptr + i * type->array.member->size;
2290 val_init(type->array.member, v);
2294 static void array_free(struct type *type, struct value *val)
2297 void *ptr = val->ptr;
2299 if (!type->array.static_size)
2301 for (i = 0; i < type->array.size; i++) {
2303 v = (void*)ptr + i * type->array.member->size;
2304 free_value(type->array.member, v);
2306 if (!type->array.static_size)
2310 static int array_compat(struct type *require, struct type *have)
2312 if (have->compat != require->compat)
2314 /* Both are arrays, so we can look at details */
2315 if (!type_compat(require->array.member, have->array.member, 0))
2317 if (have->array.unspec && require->array.unspec) {
2318 if (have->array.vsize && require->array.vsize &&
2319 have->array.vsize != require->array.vsize) // UNTESTED
2320 /* sizes might not be the same */
2321 return 0; // UNTESTED
2324 if (have->array.unspec || require->array.unspec)
2325 return 1; // UNTESTED
2326 if (require->array.vsize == NULL && have->array.vsize == NULL)
2327 return require->array.size == have->array.size;
2329 return require->array.vsize == have->array.vsize; // UNTESTED
2332 static void array_print_type(struct type *type, FILE *f)
2335 if (type->array.vsize) {
2336 struct binding *b = type->array.vsize->name;
2337 fprintf(f, "%.*s%s]", b->name.len, b->name.txt,
2338 type->array.unspec ? "::" : "");
2339 } else if (type->array.size)
2340 fprintf(f, "%d]", type->array.size);
2343 type_print(type->array.member, f);
2346 static struct type array_prototype = {
2348 .prepare_type = array_prepare_type,
2349 .print_type = array_print_type,
2350 .compat = array_compat,
2352 .size = sizeof(void*),
2353 .align = sizeof(void*),
2356 ###### declare terminals
2361 | [ NUMBER ] Type ${ {
2367 if (number_parse(num, tail, $2.txt) == 0)
2368 tok_err(c, "error: unrecognised number", &$2);
2370 tok_err(c, "error: unsupported number suffix", &$2);
2373 elements = mpz_get_ui(mpq_numref(num));
2374 if (mpz_cmp_ui(mpq_denref(num), 1) != 0) {
2375 tok_err(c, "error: array size must be an integer",
2377 } else if (mpz_cmp_ui(mpq_numref(num), 1UL << 30) >= 0)
2378 tok_err(c, "error: array size is too large",
2383 $0 = t = add_anon_type(c, &array_prototype, "array[%d]", elements );
2384 t->array.size = elements;
2385 t->array.member = $<4;
2386 t->array.vsize = NULL;
2389 | [ IDENTIFIER ] Type ${ {
2390 struct variable *v = var_ref(c, $2.txt);
2393 tok_err(c, "error: name undeclared", &$2);
2394 else if (!v->constant)
2395 tok_err(c, "error: array size must be a constant", &$2);
2397 $0 = add_anon_type(c, &array_prototype, "array[%.*s]", $2.txt.len, $2.txt.txt);
2398 $0->array.member = $<4;
2400 $0->array.vsize = v;
2405 OptType -> Type ${ $0 = $<1; }$
2408 ###### formal type grammar
2410 | [ IDENTIFIER :: OptType ] Type ${ {
2411 struct variable *v = var_decl(c, $ID.txt);
2417 $0 = add_anon_type(c, &array_prototype, "array[var]");
2418 $0->array.member = $<6;
2420 $0->array.unspec = 1;
2421 $0->array.vsize = v;
2429 | Term [ Expression ] ${ {
2430 struct binode *b = new(binode);
2437 ###### print binode cases
2439 print_exec(b->left, -1, bracket);
2441 print_exec(b->right, -1, bracket);
2445 ###### propagate binode cases
2447 /* left must be an array, right must be a number,
2448 * result is the member type of the array
2450 propagate_types(b->right, c, perr, Tnum, 0);
2451 t = propagate_types(b->left, c, perr, NULL, rules & Rnoconstant);
2452 if (!t || t->compat != array_compat) {
2453 type_err(c, "error: %1 cannot be indexed", prog, t, 0, NULL);
2456 if (!type_compat(type, t->array.member, rules)) {
2457 type_err(c, "error: have %1 but need %2", prog,
2458 t->array.member, rules, type);
2460 return t->array.member;
2464 ###### interp binode cases
2470 lleft = linterp_exec(c, b->left, <ype);
2471 right = interp_exec(c, b->right, &rtype);
2473 mpz_tdiv_q(q, mpq_numref(right.num), mpq_denref(right.num));
2477 if (ltype->array.static_size)
2480 ptr = *(void**)lleft;
2481 rvtype = ltype->array.member;
2482 if (i >= 0 && i < ltype->array.size)
2483 lrv = ptr + i * rvtype->size;
2485 val_init(ltype->array.member, &rv); // UNSAFE
2492 A `struct` is a data-type that contains one or more other data-types.
2493 It differs from an array in that each member can be of a different
2494 type, and they are accessed by name rather than by number. Thus you
2495 cannot choose an element by calculation, you need to know what you
2498 The language makes no promises about how a given structure will be
2499 stored in memory - it is free to rearrange fields to suit whatever
2500 criteria seems important.
2502 Structs are declared separately from program code - they cannot be
2503 declared in-line in a variable declaration like arrays can. A struct
2504 is given a name and this name is used to identify the type - the name
2505 is not prefixed by the word `struct` as it would be in C.
2507 Structs are only treated as the same if they have the same name.
2508 Simply having the same fields in the same order is not enough. This
2509 might change once we can create structure initializers from a list of
2512 Each component datum is identified much like a variable is declared,
2513 with a name, one or two colons, and a type. The type cannot be omitted
2514 as there is no opportunity to deduce the type from usage. An initial
2515 value can be given following an equals sign, so
2517 ##### Example: a struct type
2523 would declare a type called "complex" which has two number fields,
2524 each initialised to zero.
2526 Struct will need to be declared separately from the code that uses
2527 them, so we will need to be able to print out the declaration of a
2528 struct when reprinting the whole program. So a `print_type_decl` type
2529 function will be needed.
2531 ###### type union fields
2540 } *fields; // This is created when field_list is analysed.
2542 struct fieldlist *prev;
2545 } *field_list; // This is created during parsing
2548 ###### type functions
2549 void (*print_type_decl)(struct type *type, FILE *f);
2551 ###### value functions
2553 static void structure_init(struct type *type, struct value *val)
2557 for (i = 0; i < type->structure.nfields; i++) {
2559 v = (void*) val->ptr + type->structure.fields[i].offset;
2560 if (type->structure.fields[i].init)
2561 dup_value(type->structure.fields[i].type,
2562 type->structure.fields[i].init,
2565 val_init(type->structure.fields[i].type, v);
2569 static void structure_free(struct type *type, struct value *val)
2573 for (i = 0; i < type->structure.nfields; i++) {
2575 v = (void*)val->ptr + type->structure.fields[i].offset;
2576 free_value(type->structure.fields[i].type, v);
2580 static void free_fieldlist(struct fieldlist *f)
2584 free_fieldlist(f->prev);
2589 static void structure_free_type(struct type *t)
2592 for (i = 0; i < t->structure.nfields; i++)
2593 if (t->structure.fields[i].init) {
2594 free_value(t->structure.fields[i].type,
2595 t->structure.fields[i].init);
2597 free(t->structure.fields);
2598 free_fieldlist(t->structure.field_list);
2601 static void structure_prepare_type(struct parse_context *c,
2602 struct type *t, int parse_time)
2605 struct fieldlist *f;
2607 if (!parse_time || t->structure.fields)
2610 for (f = t->structure.field_list; f; f=f->prev) {
2614 if (f->f.type->prepare_type)
2615 f->f.type->prepare_type(c, f->f.type, 1);
2616 if (f->init == NULL)
2620 propagate_types(f->init, c, &perr, f->f.type, 0);
2621 } while (perr & Eretry);
2623 c->parse_error += 1; // NOTEST
2626 t->structure.nfields = cnt;
2627 t->structure.fields = calloc(cnt, sizeof(struct field));
2628 f = t->structure.field_list;
2630 int a = f->f.type->align;
2632 t->structure.fields[cnt] = f->f;
2633 if (t->size & (a-1))
2634 t->size = (t->size | (a-1)) + 1;
2635 t->structure.fields[cnt].offset = t->size;
2636 t->size += ((f->f.type->size - 1) | (a-1)) + 1;
2640 if (f->init && !c->parse_error) {
2641 struct value vl = interp_exec(c, f->init, NULL);
2642 t->structure.fields[cnt].init =
2643 global_alloc(c, f->f.type, NULL, &vl);
2650 static struct type structure_prototype = {
2651 .init = structure_init,
2652 .free = structure_free,
2653 .free_type = structure_free_type,
2654 .print_type_decl = structure_print_type,
2655 .prepare_type = structure_prepare_type,
2669 ###### free exec cases
2671 free_exec(cast(fieldref, e)->left);
2675 ###### declare terminals
2680 | Term . IDENTIFIER ${ {
2681 struct fieldref *fr = new_pos(fieldref, $2);
2688 ###### print exec cases
2692 struct fieldref *f = cast(fieldref, e);
2693 print_exec(f->left, -1, bracket);
2694 printf(".%.*s", f->name.len, f->name.txt);
2698 ###### ast functions
2699 static int find_struct_index(struct type *type, struct text field)
2702 for (i = 0; i < type->structure.nfields; i++)
2703 if (text_cmp(type->structure.fields[i].name, field) == 0)
2708 ###### propagate exec cases
2712 struct fieldref *f = cast(fieldref, prog);
2713 struct type *st = propagate_types(f->left, c, perr, NULL, 0);
2716 type_err(c, "error: unknown type for field access", f->left, // UNTESTED
2718 else if (st->init != structure_init)
2719 type_err(c, "error: field reference attempted on %1, not a struct",
2720 f->left, st, 0, NULL);
2721 else if (f->index == -2) {
2722 f->index = find_struct_index(st, f->name);
2724 type_err(c, "error: cannot find requested field in %1",
2725 f->left, st, 0, NULL);
2727 if (f->index >= 0) {
2728 struct type *ft = st->structure.fields[f->index].type;
2729 if (!type_compat(type, ft, rules))
2730 type_err(c, "error: have %1 but need %2", prog,
2737 ###### interp exec cases
2740 struct fieldref *f = cast(fieldref, e);
2742 struct value *lleft = linterp_exec(c, f->left, <ype);
2743 lrv = (void*)lleft->ptr + ltype->structure.fields[f->index].offset;
2744 rvtype = ltype->structure.fields[f->index].type;
2748 ###### top level grammar
2749 DeclareStruct -> struct IDENTIFIER FieldBlock Newlines ${ {
2751 add_type(c, $2.txt, &structure_prototype);
2752 t->structure.field_list = $<FB;
2756 FieldBlock -> { IN OptNL FieldLines OUT OptNL } ${ $0 = $<FL; }$
2757 | { SimpleFieldList } ${ $0 = $<SFL; }$
2758 | IN OptNL FieldLines OUT ${ $0 = $<FL; }$
2759 | SimpleFieldList EOL ${ $0 = $<SFL; }$
2761 FieldLines -> SimpleFieldList Newlines ${ $0 = $<SFL; }$
2762 | FieldLines SimpleFieldList Newlines ${
2767 SimpleFieldList -> Field ${ $0 = $<F; }$
2768 | SimpleFieldList ; Field ${
2772 | SimpleFieldList ; ${
2775 | ERROR ${ tok_err(c, "Syntax error in struct field", &$1); }$
2777 Field -> IDENTIFIER : Type = Expression ${ {
2778 $0 = calloc(1, sizeof(struct fieldlist));
2779 $0->f.name = $ID.txt;
2780 $0->f.type = $<Type;
2784 | IDENTIFIER : Type ${
2785 $0 = calloc(1, sizeof(struct fieldlist));
2786 $0->f.name = $ID.txt;
2787 $0->f.type = $<Type;
2790 ###### forward decls
2791 static void structure_print_type(struct type *t, FILE *f);
2793 ###### value functions
2794 static void structure_print_type(struct type *t, FILE *f)
2798 fprintf(f, "struct %.*s\n", t->name.len, t->name.txt);
2800 for (i = 0; i < t->structure.nfields; i++) {
2801 struct field *fl = t->structure.fields + i;
2802 fprintf(f, " %.*s : ", fl->name.len, fl->name.txt);
2803 type_print(fl->type, f);
2804 if (fl->type->print && fl->init) {
2806 if (fl->type == Tstr)
2807 fprintf(f, "\""); // UNTESTED
2808 print_value(fl->type, fl->init, f);
2809 if (fl->type == Tstr)
2810 fprintf(f, "\""); // UNTESTED
2816 ###### print type decls
2821 while (target != 0) {
2823 for (t = context.typelist; t ; t=t->next)
2824 if (!t->anon && t->print_type_decl &&
2834 t->print_type_decl(t, stdout);
2842 A function is a chunk of code which can be passed parameters and can
2843 return results. Each function has a type which includes the set of
2844 parameters and the return value. As yet these types cannot be declared
2845 separately from the function itself.
2847 The parameters can be specified either in parentheses as a ';' separated
2850 ##### Example: function 1
2852 func main(av:[ac::number]string; env:[envc::number]string)
2855 or as an indented list of one parameter per line (though each line can
2856 be a ';' separated list)
2858 ##### Example: function 2
2861 argv:[argc::number]string
2862 env:[envc::number]string
2866 In the first case a return type can follow the parentheses after a colon,
2867 in the second it is given on a line starting with the word `return`.
2869 ##### Example: functions that return
2871 func add(a:number; b:number): number
2881 Rather than returning a type, the function can specify a set of local
2882 variables to return as a struct. The values of these variables when the
2883 function exits will be provided to the caller. For this the return type
2884 is replaced with a block of result declarations, either in parentheses
2885 or bracketed by `return` and `do`.
2887 ##### Example: functions returning multiple variables
2889 func to_cartesian(rho:number; theta:number):(x:number; y:number)
2902 For constructing the lists we use a `List` binode, which will be
2903 further detailed when Expression Lists are introduced.
2905 ###### type union fields
2908 struct binode *params;
2909 struct type *return_type;
2910 struct variable *scope;
2911 int inline_result; // return value is at start of 'local'
2915 ###### value union fields
2916 struct exec *function;
2918 ###### type functions
2919 void (*check_args)(struct parse_context *c, enum prop_err *perr,
2920 struct type *require, struct exec *args);
2922 ###### value functions
2924 static void function_free(struct type *type, struct value *val)
2926 free_exec(val->function);
2927 val->function = NULL;
2930 static int function_compat(struct type *require, struct type *have)
2932 // FIXME can I do anything here yet?
2936 static void function_check_args(struct parse_context *c, enum prop_err *perr,
2937 struct type *require, struct exec *args)
2939 /* This should be 'compat', but we don't have a 'tuple' type to
2940 * hold the type of 'args'
2942 struct binode *arg = cast(binode, args);
2943 struct binode *param = require->function.params;
2946 struct var *pv = cast(var, param->left);
2948 type_err(c, "error: insufficient arguments to function.",
2949 args, NULL, 0, NULL);
2953 propagate_types(arg->left, c, perr, pv->var->type, 0);
2954 param = cast(binode, param->right);
2955 arg = cast(binode, arg->right);
2958 type_err(c, "error: too many arguments to function.",
2959 args, NULL, 0, NULL);
2962 static void function_print(struct type *type, struct value *val, FILE *f)
2964 print_exec(val->function, 1, 0);
2967 static void function_print_type_decl(struct type *type, FILE *f)
2971 for (b = type->function.params; b; b = cast(binode, b->right)) {
2972 struct variable *v = cast(var, b->left)->var;
2973 fprintf(f, "%.*s%s", v->name->name.len, v->name->name.txt,
2974 v->constant ? "::" : ":");
2975 type_print(v->type, f);
2980 if (type->function.return_type != Tnone) {
2982 if (type->function.inline_result) {
2984 struct type *t = type->function.return_type;
2986 for (i = 0; i < t->structure.nfields; i++) {
2987 struct field *fl = t->structure.fields + i;
2990 fprintf(f, "%.*s:", fl->name.len, fl->name.txt);
2991 type_print(fl->type, f);
2995 type_print(type->function.return_type, f);
3000 static void function_free_type(struct type *t)
3002 free_exec(t->function.params);
3005 static struct type function_prototype = {
3006 .size = sizeof(void*),
3007 .align = sizeof(void*),
3008 .free = function_free,
3009 .compat = function_compat,
3010 .check_args = function_check_args,
3011 .print = function_print,
3012 .print_type_decl = function_print_type_decl,
3013 .free_type = function_free_type,
3016 ###### declare terminals
3026 FuncName -> IDENTIFIER ${ {
3027 struct variable *v = var_decl(c, $1.txt);
3028 struct var *e = new_pos(var, $1);
3034 v = var_ref(c, $1.txt);
3036 type_err(c, "error: function '%v' redeclared",
3038 type_err(c, "info: this is where '%v' was first declared",
3039 v->where_decl, NULL, 0, NULL);
3045 Args -> ArgsLine NEWLINE ${ $0 = $<AL; }$
3046 | Args ArgsLine NEWLINE ${ {
3047 struct binode *b = $<AL;
3048 struct binode **bp = &b;
3050 bp = (struct binode **)&(*bp)->left;
3055 ArgsLine -> ${ $0 = NULL; }$
3056 | Varlist ${ $0 = $<1; }$
3057 | Varlist ; ${ $0 = $<1; }$
3059 Varlist -> Varlist ; ArgDecl ${
3073 ArgDecl -> IDENTIFIER : FormalType ${ {
3074 struct variable *v = var_decl(c, $1.txt);
3080 ##### Function calls
3082 A function call can appear either as an expression or as a statement.
3083 We use a new 'Funcall' binode type to link the function with a list of
3084 arguments, form with the 'List' nodes.
3086 We have already seen the "Term" which is how a function call can appear
3087 in an expression. To parse a function call into a statement we include
3088 it in the "SimpleStatement Grammar" which will be described later.
3094 | Term ( ExpressionList ) ${ {
3095 struct binode *b = new(binode);
3098 b->right = reorder_bilist($<EL);
3102 struct binode *b = new(binode);
3109 ###### SimpleStatement Grammar
3111 | Term ( ExpressionList ) ${ {
3112 struct binode *b = new(binode);
3115 b->right = reorder_bilist($<EL);
3119 ###### print binode cases
3122 do_indent(indent, "");
3123 print_exec(b->left, -1, bracket);
3125 for (b = cast(binode, b->right); b; b = cast(binode, b->right)) {
3128 print_exec(b->left, -1, bracket);
3138 ###### propagate binode cases
3141 /* Every arg must match formal parameter, and result
3142 * is return type of function
3144 struct binode *args = cast(binode, b->right);
3145 struct var *v = cast(var, b->left);
3147 if (!v->var->type || v->var->type->check_args == NULL) {
3148 type_err(c, "error: attempt to call a non-function.",
3149 prog, NULL, 0, NULL);
3152 v->var->type->check_args(c, perr, v->var->type, args);
3153 return v->var->type->function.return_type;
3156 ###### interp binode cases
3159 struct var *v = cast(var, b->left);
3160 struct type *t = v->var->type;
3161 void *oldlocal = c->local;
3162 int old_size = c->local_size;
3163 void *local = calloc(1, t->function.local_size);
3164 struct value *fbody = var_value(c, v->var);
3165 struct binode *arg = cast(binode, b->right);
3166 struct binode *param = t->function.params;
3169 struct var *pv = cast(var, param->left);
3170 struct type *vtype = NULL;
3171 struct value val = interp_exec(c, arg->left, &vtype);
3173 c->local = local; c->local_size = t->function.local_size;
3174 lval = var_value(c, pv->var);
3175 c->local = oldlocal; c->local_size = old_size;
3176 memcpy(lval, &val, vtype->size);
3177 param = cast(binode, param->right);
3178 arg = cast(binode, arg->right);
3180 c->local = local; c->local_size = t->function.local_size;
3181 if (t->function.inline_result && dtype) {
3182 _interp_exec(c, fbody->function, NULL, NULL);
3183 memcpy(dest, local, dtype->size);
3184 rvtype = ret.type = NULL;
3186 rv = interp_exec(c, fbody->function, &rvtype);
3187 c->local = oldlocal; c->local_size = old_size;
3192 ## Complex executables: statements and expressions
3194 Now that we have types and values and variables and most of the basic
3195 Terms which provide access to these, we can explore the more complex
3196 code that combine all of these to get useful work done. Specifically
3197 statements and expressions.
3199 Expressions are various combinations of Terms. We will use operator
3200 precedence to ensure correct parsing. The simplest Expression is just a
3201 Term - others will follow.
3206 Expression -> Term ${ $0 = $<Term; }$
3207 ## expression grammar
3209 ### Expressions: Conditional
3211 Our first user of the `binode` will be conditional expressions, which
3212 is a bit odd as they actually have three components. That will be
3213 handled by having 2 binodes for each expression. The conditional
3214 expression is the lowest precedence operator which is why we define it
3215 first - to start the precedence list.
3217 Conditional expressions are of the form "value `if` condition `else`
3218 other_value". They associate to the right, so everything to the right
3219 of `else` is part of an else value, while only a higher-precedence to
3220 the left of `if` is the if values. Between `if` and `else` there is no
3221 room for ambiguity, so a full conditional expression is allowed in
3227 ###### declare terminals
3231 ###### expression grammar
3233 | Expression if Expression else Expression $$ifelse ${ {
3234 struct binode *b1 = new(binode);
3235 struct binode *b2 = new(binode);
3245 ###### print binode cases
3248 b2 = cast(binode, b->right);
3249 if (bracket) printf("(");
3250 print_exec(b2->left, -1, bracket);
3252 print_exec(b->left, -1, bracket);
3254 print_exec(b2->right, -1, bracket);
3255 if (bracket) printf(")");
3258 ###### propagate binode cases
3261 /* cond must be Tbool, others must match */
3262 struct binode *b2 = cast(binode, b->right);
3265 propagate_types(b->left, c, perr, Tbool, 0);
3266 t = propagate_types(b2->left, c, perr, type, Rnolabel);
3267 t2 = propagate_types(b2->right, c, perr, type ?: t, Rnolabel);
3271 ###### interp binode cases
3274 struct binode *b2 = cast(binode, b->right);
3275 left = interp_exec(c, b->left, <ype);
3277 rv = interp_exec(c, b2->left, &rvtype); // UNTESTED
3279 rv = interp_exec(c, b2->right, &rvtype);
3285 We take a brief detour, now that we have expressions, to describe lists
3286 of expressions. These will be needed for function parameters and
3287 possibly other situations. They seem generic enough to introduce here
3288 to be used elsewhere.
3290 And ExpressionList will use the `List` type of `binode`, building up at
3291 the end. And place where they are used will probably call
3292 `reorder_bilist()` to get a more normal first/next arrangement.
3294 ###### declare terminals
3297 `List` execs have no implicit semantics, so they are never propagated or
3298 interpreted. The can be printed as a comma separate list, which is how
3299 they are parsed. Note they are also used for function formal parameter
3300 lists. In that case a separate function is used to print them.
3302 ###### print binode cases
3306 print_exec(b->left, -1, bracket);
3309 b = cast(binode, b->right);
3313 ###### propagate binode cases
3314 case List: abort(); // NOTEST
3315 ###### interp binode cases
3316 case List: abort(); // NOTEST
3321 ExpressionList -> ExpressionList , Expression ${
3334 ### Expressions: Boolean
3336 The next class of expressions to use the `binode` will be Boolean
3337 expressions. "`and then`" and "`or else`" are similar to `and` and `or`
3338 have same corresponding precendence. The difference is that they don't
3339 evaluate the second expression if not necessary.
3348 ###### declare terminals
3353 ###### expression grammar
3354 | Expression or Expression ${ {
3355 struct binode *b = new(binode);
3361 | Expression or else Expression ${ {
3362 struct binode *b = new(binode);
3369 | Expression and Expression ${ {
3370 struct binode *b = new(binode);
3376 | Expression and then Expression ${ {
3377 struct binode *b = new(binode);
3384 | not Expression ${ {
3385 struct binode *b = new(binode);
3391 ###### print binode cases
3393 if (bracket) printf("(");
3394 print_exec(b->left, -1, bracket);
3396 print_exec(b->right, -1, bracket);
3397 if (bracket) printf(")");
3400 if (bracket) printf("(");
3401 print_exec(b->left, -1, bracket);
3402 printf(" and then ");
3403 print_exec(b->right, -1, bracket);
3404 if (bracket) printf(")");
3407 if (bracket) printf("(");
3408 print_exec(b->left, -1, bracket);
3410 print_exec(b->right, -1, bracket);
3411 if (bracket) printf(")");
3414 if (bracket) printf("(");
3415 print_exec(b->left, -1, bracket);
3416 printf(" or else ");
3417 print_exec(b->right, -1, bracket);
3418 if (bracket) printf(")");
3421 if (bracket) printf("(");
3423 print_exec(b->right, -1, bracket);
3424 if (bracket) printf(")");
3427 ###### propagate binode cases
3433 /* both must be Tbool, result is Tbool */
3434 propagate_types(b->left, c, perr, Tbool, 0);
3435 propagate_types(b->right, c, perr, Tbool, 0);
3436 if (type && type != Tbool)
3437 type_err(c, "error: %1 operation found where %2 expected", prog,
3441 ###### interp binode cases
3443 rv = interp_exec(c, b->left, &rvtype);
3444 right = interp_exec(c, b->right, &rtype);
3445 rv.bool = rv.bool && right.bool;
3448 rv = interp_exec(c, b->left, &rvtype);
3450 rv = interp_exec(c, b->right, NULL);
3453 rv = interp_exec(c, b->left, &rvtype);
3454 right = interp_exec(c, b->right, &rtype);
3455 rv.bool = rv.bool || right.bool;
3458 rv = interp_exec(c, b->left, &rvtype);
3460 rv = interp_exec(c, b->right, NULL);
3463 rv = interp_exec(c, b->right, &rvtype);
3467 ### Expressions: Comparison
3469 Of slightly higher precedence that Boolean expressions are Comparisons.
3470 A comparison takes arguments of any comparable type, but the two types
3473 To simplify the parsing we introduce an `eop` which can record an
3474 expression operator, and the `CMPop` non-terminal will match one of them.
3481 ###### ast functions
3482 static void free_eop(struct eop *e)
3496 ###### declare terminals
3497 $LEFT < > <= >= == != CMPop
3499 ###### expression grammar
3500 | Expression CMPop Expression ${ {
3501 struct binode *b = new(binode);
3511 CMPop -> < ${ $0.op = Less; }$
3512 | > ${ $0.op = Gtr; }$
3513 | <= ${ $0.op = LessEq; }$
3514 | >= ${ $0.op = GtrEq; }$
3515 | == ${ $0.op = Eql; }$
3516 | != ${ $0.op = NEql; }$
3518 ###### print binode cases
3526 if (bracket) printf("(");
3527 print_exec(b->left, -1, bracket);
3529 case Less: printf(" < "); break;
3530 case LessEq: printf(" <= "); break;
3531 case Gtr: printf(" > "); break;
3532 case GtrEq: printf(" >= "); break;
3533 case Eql: printf(" == "); break;
3534 case NEql: printf(" != "); break;
3535 default: abort(); // NOTEST
3537 print_exec(b->right, -1, bracket);
3538 if (bracket) printf(")");
3541 ###### propagate binode cases
3548 /* Both must match but not be labels, result is Tbool */
3549 t = propagate_types(b->left, c, perr, NULL, Rnolabel);
3551 propagate_types(b->right, c, perr, t, 0);
3553 t = propagate_types(b->right, c, perr, NULL, Rnolabel); // UNTESTED
3555 t = propagate_types(b->left, c, perr, t, 0); // UNTESTED
3557 if (!type_compat(type, Tbool, 0))
3558 type_err(c, "error: Comparison returns %1 but %2 expected", prog,
3559 Tbool, rules, type);
3562 ###### interp binode cases
3571 left = interp_exec(c, b->left, <ype);
3572 right = interp_exec(c, b->right, &rtype);
3573 cmp = value_cmp(ltype, rtype, &left, &right);
3576 case Less: rv.bool = cmp < 0; break;
3577 case LessEq: rv.bool = cmp <= 0; break;
3578 case Gtr: rv.bool = cmp > 0; break;
3579 case GtrEq: rv.bool = cmp >= 0; break;
3580 case Eql: rv.bool = cmp == 0; break;
3581 case NEql: rv.bool = cmp != 0; break;
3582 default: rv.bool = 0; break; // NOTEST
3587 ### Expressions: Arithmetic etc.
3589 The remaining expressions with the highest precedence are arithmetic,
3590 string concatenation, and string conversion. String concatenation
3591 (`++`) has the same precedence as multiplication and division, but lower
3594 String conversion is a temporary feature until I get a better type
3595 system. `$` is a prefix operator which expects a string and returns
3598 `+` and `-` are both infix and prefix operations (where they are
3599 absolute value and negation). These have different operator names.
3601 We also have a 'Bracket' operator which records where parentheses were
3602 found. This makes it easy to reproduce these when printing. Possibly I
3603 should only insert brackets were needed for precedence. Putting
3604 parentheses around an expression converts it into a Term,
3614 ###### declare terminals
3620 ###### expression grammar
3621 | Expression Eop Expression ${ {
3622 struct binode *b = new(binode);
3629 | Expression Top Expression ${ {
3630 struct binode *b = new(binode);
3637 | Uop Expression ${ {
3638 struct binode *b = new(binode);
3646 | ( Expression ) ${ {
3647 struct binode *b = new_pos(binode, $1);
3656 Eop -> + ${ $0.op = Plus; }$
3657 | - ${ $0.op = Minus; }$
3659 Uop -> + ${ $0.op = Absolute; }$
3660 | - ${ $0.op = Negate; }$
3661 | $ ${ $0.op = StringConv; }$
3663 Top -> * ${ $0.op = Times; }$
3664 | / ${ $0.op = Divide; }$
3665 | % ${ $0.op = Rem; }$
3666 | ++ ${ $0.op = Concat; }$
3668 ###### print binode cases
3675 if (bracket) printf("(");
3676 print_exec(b->left, indent, bracket);
3678 case Plus: fputs(" + ", stdout); break;
3679 case Minus: fputs(" - ", stdout); break;
3680 case Times: fputs(" * ", stdout); break;
3681 case Divide: fputs(" / ", stdout); break;
3682 case Rem: fputs(" % ", stdout); break;
3683 case Concat: fputs(" ++ ", stdout); break;
3684 default: abort(); // NOTEST
3686 print_exec(b->right, indent, bracket);
3687 if (bracket) printf(")");
3692 if (bracket) printf("(");
3694 case Absolute: fputs("+", stdout); break;
3695 case Negate: fputs("-", stdout); break;
3696 case StringConv: fputs("$", stdout); break;
3697 default: abort(); // NOTEST
3699 print_exec(b->right, indent, bracket);
3700 if (bracket) printf(")");
3704 print_exec(b->right, indent, bracket);
3708 ###### propagate binode cases
3714 /* both must be numbers, result is Tnum */
3717 /* as propagate_types ignores a NULL,
3718 * unary ops fit here too */
3719 propagate_types(b->left, c, perr, Tnum, 0);
3720 propagate_types(b->right, c, perr, Tnum, 0);
3721 if (!type_compat(type, Tnum, 0))
3722 type_err(c, "error: Arithmetic returns %1 but %2 expected", prog,
3727 /* both must be Tstr, result is Tstr */
3728 propagate_types(b->left, c, perr, Tstr, 0);
3729 propagate_types(b->right, c, perr, Tstr, 0);
3730 if (!type_compat(type, Tstr, 0))
3731 type_err(c, "error: Concat returns %1 but %2 expected", prog,
3736 /* op must be string, result is number */
3737 propagate_types(b->left, c, perr, Tstr, 0);
3738 if (!type_compat(type, Tnum, 0))
3739 type_err(c, // UNTESTED
3740 "error: Can only convert string to number, not %1",
3741 prog, type, 0, NULL);
3745 return propagate_types(b->right, c, perr, type, 0);
3747 ###### interp binode cases
3750 rv = interp_exec(c, b->left, &rvtype);
3751 right = interp_exec(c, b->right, &rtype);
3752 mpq_add(rv.num, rv.num, right.num);
3755 rv = interp_exec(c, b->left, &rvtype);
3756 right = interp_exec(c, b->right, &rtype);
3757 mpq_sub(rv.num, rv.num, right.num);
3760 rv = interp_exec(c, b->left, &rvtype);
3761 right = interp_exec(c, b->right, &rtype);
3762 mpq_mul(rv.num, rv.num, right.num);
3765 rv = interp_exec(c, b->left, &rvtype);
3766 right = interp_exec(c, b->right, &rtype);
3767 mpq_div(rv.num, rv.num, right.num);
3772 left = interp_exec(c, b->left, <ype);
3773 right = interp_exec(c, b->right, &rtype);
3774 mpz_init(l); mpz_init(r); mpz_init(rem);
3775 mpz_tdiv_q(l, mpq_numref(left.num), mpq_denref(left.num));
3776 mpz_tdiv_q(r, mpq_numref(right.num), mpq_denref(right.num));
3777 mpz_tdiv_r(rem, l, r);
3778 val_init(Tnum, &rv);
3779 mpq_set_z(rv.num, rem);
3780 mpz_clear(r); mpz_clear(l); mpz_clear(rem);
3785 rv = interp_exec(c, b->right, &rvtype);
3786 mpq_neg(rv.num, rv.num);
3789 rv = interp_exec(c, b->right, &rvtype);
3790 mpq_abs(rv.num, rv.num);
3793 rv = interp_exec(c, b->right, &rvtype);
3796 left = interp_exec(c, b->left, <ype);
3797 right = interp_exec(c, b->right, &rtype);
3799 rv.str = text_join(left.str, right.str);
3802 right = interp_exec(c, b->right, &rvtype);
3806 struct text tx = right.str;
3809 if (tx.txt[0] == '-') {
3810 neg = 1; // UNTESTED
3811 tx.txt++; // UNTESTED
3812 tx.len--; // UNTESTED
3814 if (number_parse(rv.num, tail, tx) == 0)
3815 mpq_init(rv.num); // UNTESTED
3817 mpq_neg(rv.num, rv.num); // UNTESTED
3819 printf("Unsupported suffix: %.*s\n", tx.len, tx.txt); // UNTESTED
3823 ###### value functions
3825 static struct text text_join(struct text a, struct text b)
3828 rv.len = a.len + b.len;
3829 rv.txt = malloc(rv.len);
3830 memcpy(rv.txt, a.txt, a.len);
3831 memcpy(rv.txt+a.len, b.txt, b.len);
3835 ### Blocks, Statements, and Statement lists.
3837 Now that we have expressions out of the way we need to turn to
3838 statements. There are simple statements and more complex statements.
3839 Simple statements do not contain (syntactic) newlines, complex statements do.
3841 Statements often come in sequences and we have corresponding simple
3842 statement lists and complex statement lists.
3843 The former comprise only simple statements separated by semicolons.
3844 The later comprise complex statements and simple statement lists. They are
3845 separated by newlines. Thus the semicolon is only used to separate
3846 simple statements on the one line. This may be overly restrictive,
3847 but I'm not sure I ever want a complex statement to share a line with
3850 Note that a simple statement list can still use multiple lines if
3851 subsequent lines are indented, so
3853 ###### Example: wrapped simple statement list
3858 is a single simple statement list. This might allow room for
3859 confusion, so I'm not set on it yet.
3861 A simple statement list needs no extra syntax. A complex statement
3862 list has two syntactic forms. It can be enclosed in braces (much like
3863 C blocks), or it can be introduced by an indent and continue until an
3864 unindented newline (much like Python blocks). With this extra syntax
3865 it is referred to as a block.
3867 Note that a block does not have to include any newlines if it only
3868 contains simple statements. So both of:
3870 if condition: a=b; d=f
3872 if condition { a=b; print f }
3876 In either case the list is constructed from a `binode` list with
3877 `Block` as the operator. When parsing the list it is most convenient
3878 to append to the end, so a list is a list and a statement. When using
3879 the list it is more convenient to consider a list to be a statement
3880 and a list. So we need a function to re-order a list.
3881 `reorder_bilist` serves this purpose.
3883 The only stand-alone statement we introduce at this stage is `pass`
3884 which does nothing and is represented as a `NULL` pointer in a `Block`
3885 list. Other stand-alone statements will follow once the infrastructure
3888 As many statements will use binodes, we declare a binode pointer 'b' in
3889 the common header for all reductions to use.
3891 ###### Parser: reduce
3902 Block -> { IN OptNL Statementlist OUT OptNL } ${ $0 = $<Sl; }$
3903 | { SimpleStatements } ${ $0 = reorder_bilist($<SS); }$
3904 | SimpleStatements ; ${ $0 = reorder_bilist($<SS); }$
3905 | SimpleStatements EOL ${ $0 = reorder_bilist($<SS); }$
3906 | IN OptNL Statementlist OUT ${ $0 = $<Sl; }$
3908 OpenBlock -> OpenScope { IN OptNL Statementlist OUT OptNL } ${ $0 = $<Sl; }$
3909 | OpenScope { SimpleStatements } ${ $0 = reorder_bilist($<SS); }$
3910 | OpenScope SimpleStatements ; ${ $0 = reorder_bilist($<SS); }$
3911 | OpenScope SimpleStatements EOL ${ $0 = reorder_bilist($<SS); }$
3912 | IN OpenScope OptNL Statementlist OUT ${ $0 = $<Sl; }$
3914 UseBlock -> { OpenScope IN OptNL Statementlist OUT OptNL } ${ $0 = $<Sl; }$
3915 | { OpenScope SimpleStatements } ${ $0 = reorder_bilist($<SS); }$
3916 | IN OpenScope OptNL Statementlist OUT ${ $0 = $<Sl; }$
3918 ColonBlock -> { IN OptNL Statementlist OUT OptNL } ${ $0 = $<Sl; }$
3919 | { SimpleStatements } ${ $0 = reorder_bilist($<SS); }$
3920 | : SimpleStatements ; ${ $0 = reorder_bilist($<SS); }$
3921 | : SimpleStatements EOL ${ $0 = reorder_bilist($<SS); }$
3922 | : IN OptNL Statementlist OUT ${ $0 = $<Sl; }$
3924 Statementlist -> ComplexStatements ${ $0 = reorder_bilist($<CS); }$
3926 ComplexStatements -> ComplexStatements ComplexStatement ${
3936 | ComplexStatement ${
3948 ComplexStatement -> SimpleStatements Newlines ${
3949 $0 = reorder_bilist($<SS);
3951 | SimpleStatements ; Newlines ${
3952 $0 = reorder_bilist($<SS);
3954 ## ComplexStatement Grammar
3957 SimpleStatements -> SimpleStatements ; SimpleStatement ${
3963 | SimpleStatement ${
3972 SimpleStatement -> pass ${ $0 = NULL; }$
3973 | ERROR ${ tok_err(c, "Syntax error in statement", &$1); }$
3974 ## SimpleStatement Grammar
3976 ###### print binode cases
3980 if (b->left == NULL) // UNTESTED
3981 printf("pass"); // UNTESTED
3983 print_exec(b->left, indent, bracket); // UNTESTED
3984 if (b->right) { // UNTESTED
3985 printf("; "); // UNTESTED
3986 print_exec(b->right, indent, bracket); // UNTESTED
3989 // block, one per line
3990 if (b->left == NULL)
3991 do_indent(indent, "pass\n");
3993 print_exec(b->left, indent, bracket);
3995 print_exec(b->right, indent, bracket);
3999 ###### propagate binode cases
4002 /* If any statement returns something other than Tnone
4003 * or Tbool then all such must return same type.
4004 * As each statement may be Tnone or something else,
4005 * we must always pass NULL (unknown) down, otherwise an incorrect
4006 * error might occur. We never return Tnone unless it is
4011 for (e = b; e; e = cast(binode, e->right)) {
4012 t = propagate_types(e->left, c, perr, NULL, rules);
4013 if ((rules & Rboolok) && (t == Tbool || t == Tnone))
4015 if (t == Tnone && e->right)
4016 /* Only the final statement *must* return a value
4024 type_err(c, "error: expected %1%r, found %2",
4025 e->left, type, rules, t);
4031 ###### interp binode cases
4033 while (rvtype == Tnone &&
4036 rv = interp_exec(c, b->left, &rvtype);
4037 b = cast(binode, b->right);
4041 ### The Print statement
4043 `print` is a simple statement that takes a comma-separated list of
4044 expressions and prints the values separated by spaces and terminated
4045 by a newline. No control of formatting is possible.
4047 `print` uses `ExpressionList` to collect the expressions and stores them
4048 on the left side of a `Print` binode unlessthere is a trailing comma
4049 when the list is stored on the `right` side and no trailing newline is
4055 ##### declare terminals
4058 ###### SimpleStatement Grammar
4060 | print ExpressionList ${
4061 $0 = b = new(binode);
4064 b->left = reorder_bilist($<EL);
4066 | print ExpressionList , ${ {
4067 $0 = b = new(binode);
4069 b->right = reorder_bilist($<EL);
4073 $0 = b = new(binode);
4079 ###### print binode cases
4082 do_indent(indent, "print");
4084 print_exec(b->right, -1, bracket);
4087 print_exec(b->left, -1, bracket);
4092 ###### propagate binode cases
4095 /* don't care but all must be consistent */
4097 b = cast(binode, b->left);
4099 b = cast(binode, b->right);
4101 propagate_types(b->left, c, perr, NULL, Rnolabel);
4102 b = cast(binode, b->right);
4106 ###### interp binode cases
4110 struct binode *b2 = cast(binode, b->left);
4112 b2 = cast(binode, b->right);
4113 for (; b2; b2 = cast(binode, b2->right)) {
4114 left = interp_exec(c, b2->left, <ype);
4115 print_value(ltype, &left, stdout);
4116 free_value(ltype, &left);
4120 if (b->right == NULL)
4126 ###### Assignment statement
4128 An assignment will assign a value to a variable, providing it hasn't
4129 been declared as a constant. The analysis phase ensures that the type
4130 will be correct so the interpreter just needs to perform the
4131 calculation. There is a form of assignment which declares a new
4132 variable as well as assigning a value. If a name is assigned before
4133 it is declared, and error will be raised as the name is created as
4134 `Tlabel` and it is illegal to assign to such names.
4140 ###### declare terminals
4143 ###### SimpleStatement Grammar
4144 | Term = Expression ${
4145 $0 = b= new(binode);
4150 | VariableDecl = Expression ${
4151 $0 = b= new(binode);
4158 if ($1->var->where_set == NULL) {
4160 "Variable declared with no type or value: %v",
4164 $0 = b = new(binode);
4171 ###### print binode cases
4174 do_indent(indent, "");
4175 print_exec(b->left, indent, bracket);
4177 print_exec(b->right, indent, bracket);
4184 struct variable *v = cast(var, b->left)->var;
4185 do_indent(indent, "");
4186 print_exec(b->left, indent, bracket);
4187 if (cast(var, b->left)->var->constant) {
4189 if (v->explicit_type) {
4190 type_print(v->type, stdout);
4195 if (v->explicit_type) {
4196 type_print(v->type, stdout);
4202 print_exec(b->right, indent, bracket);
4209 ###### propagate binode cases
4213 /* Both must match and not be labels,
4214 * Type must support 'dup',
4215 * For Assign, left must not be constant.
4218 t = propagate_types(b->left, c, perr, NULL,
4219 Rnolabel | (b->op == Assign ? Rnoconstant : 0));
4224 if (propagate_types(b->right, c, perr, t, 0) != t)
4225 if (b->left->type == Xvar)
4226 type_err(c, "info: variable '%v' was set as %1 here.",
4227 cast(var, b->left)->var->where_set, t, rules, NULL);
4229 t = propagate_types(b->right, c, perr, NULL, Rnolabel);
4231 propagate_types(b->left, c, perr, t,
4232 (b->op == Assign ? Rnoconstant : 0));
4234 if (t && t->dup == NULL && t->name.txt[0] != ' ') // HACK
4235 type_err(c, "error: cannot assign value of type %1", b, t, 0, NULL);
4240 ###### interp binode cases
4243 lleft = linterp_exec(c, b->left, <ype);
4245 dinterp_exec(c, b->right, lleft, ltype, 1);
4251 struct variable *v = cast(var, b->left)->var;
4254 val = var_value(c, v);
4255 if (v->type->prepare_type)
4256 v->type->prepare_type(c, v->type, 0);
4258 dinterp_exec(c, b->right, val, v->type, 0);
4260 val_init(v->type, val);
4264 ### The `use` statement
4266 The `use` statement is the last "simple" statement. It is needed when a
4267 statement block can return a value. This includes the body of a
4268 function which has a return type, and the "condition" code blocks in
4269 `if`, `while`, and `switch` statements.
4274 ###### declare terminals
4277 ###### SimpleStatement Grammar
4279 $0 = b = new_pos(binode, $1);
4282 if (b->right->type == Xvar) {
4283 struct var *v = cast(var, b->right);
4284 if (v->var->type == Tnone) {
4285 /* Convert this to a label */
4288 v->var->type = Tlabel;
4289 val = global_alloc(c, Tlabel, v->var, NULL);
4295 ###### print binode cases
4298 do_indent(indent, "use ");
4299 print_exec(b->right, -1, bracket);
4304 ###### propagate binode cases
4307 /* result matches value */
4308 return propagate_types(b->right, c, perr, type, 0);
4310 ###### interp binode cases
4313 rv = interp_exec(c, b->right, &rvtype);
4316 ### The Conditional Statement
4318 This is the biggy and currently the only complex statement. This
4319 subsumes `if`, `while`, `do/while`, `switch`, and some parts of `for`.
4320 It is comprised of a number of parts, all of which are optional though
4321 set combinations apply. Each part is (usually) a key word (`then` is
4322 sometimes optional) followed by either an expression or a code block,
4323 except the `casepart` which is a "key word and an expression" followed
4324 by a code block. The code-block option is valid for all parts and,
4325 where an expression is also allowed, the code block can use the `use`
4326 statement to report a value. If the code block does not report a value
4327 the effect is similar to reporting `True`.
4329 The `else` and `case` parts, as well as `then` when combined with
4330 `if`, can contain a `use` statement which will apply to some
4331 containing conditional statement. `for` parts, `do` parts and `then`
4332 parts used with `for` can never contain a `use`, except in some
4333 subordinate conditional statement.
4335 If there is a `forpart`, it is executed first, only once.
4336 If there is a `dopart`, then it is executed repeatedly providing
4337 always that the `condpart` or `cond`, if present, does not return a non-True
4338 value. `condpart` can fail to return any value if it simply executes
4339 to completion. This is treated the same as returning `True`.
4341 If there is a `thenpart` it will be executed whenever the `condpart`
4342 or `cond` returns True (or does not return any value), but this will happen
4343 *after* `dopart` (when present).
4345 If `elsepart` is present it will be executed at most once when the
4346 condition returns `False` or some value that isn't `True` and isn't
4347 matched by any `casepart`. If there are any `casepart`s, they will be
4348 executed when the condition returns a matching value.
4350 The particular sorts of values allowed in case parts has not yet been
4351 determined in the language design, so nothing is prohibited.
4353 The various blocks in this complex statement potentially provide scope
4354 for variables as described earlier. Each such block must include the
4355 "OpenScope" nonterminal before parsing the block, and must call
4356 `var_block_close()` when closing the block.
4358 The code following "`if`", "`switch`" and "`for`" does not get its own
4359 scope, but is in a scope covering the whole statement, so names
4360 declared there cannot be redeclared elsewhere. Similarly the
4361 condition following "`while`" is in a scope the covers the body
4362 ("`do`" part) of the loop, and which does not allow conditional scope
4363 extension. Code following "`then`" (both looping and non-looping),
4364 "`else`" and "`case`" each get their own local scope.
4366 The type requirements on the code block in a `whilepart` are quite
4367 unusal. It is allowed to return a value of some identifiable type, in
4368 which case the loop aborts and an appropriate `casepart` is run, or it
4369 can return a Boolean, in which case the loop either continues to the
4370 `dopart` (on `True`) or aborts and runs the `elsepart` (on `False`).
4371 This is different both from the `ifpart` code block which is expected to
4372 return a Boolean, or the `switchpart` code block which is expected to
4373 return the same type as the casepart values. The correct analysis of
4374 the type of the `whilepart` code block is the reason for the
4375 `Rboolok` flag which is passed to `propagate_types()`.
4377 The `cond_statement` cannot fit into a `binode` so a new `exec` is
4378 defined. As there are two scopes which cover multiple parts - one for
4379 the whole statement and one for "while" and "do" - and as we will use
4380 the 'struct exec' to track scopes, we actually need two new types of
4381 exec. One is a `binode` for the looping part, the rest is the
4382 `cond_statement`. The `cond_statement` will use an auxilliary `struct
4383 casepart` to track a list of case parts.
4394 struct exec *action;
4395 struct casepart *next;
4397 struct cond_statement {
4399 struct exec *forpart, *condpart, *thenpart, *elsepart;
4400 struct binode *looppart;
4401 struct casepart *casepart;
4404 ###### ast functions
4406 static void free_casepart(struct casepart *cp)
4410 free_exec(cp->value);
4411 free_exec(cp->action);
4418 static void free_cond_statement(struct cond_statement *s)
4422 free_exec(s->forpart);
4423 free_exec(s->condpart);
4424 free_exec(s->looppart);
4425 free_exec(s->thenpart);
4426 free_exec(s->elsepart);
4427 free_casepart(s->casepart);
4431 ###### free exec cases
4432 case Xcond_statement: free_cond_statement(cast(cond_statement, e)); break;
4434 ###### ComplexStatement Grammar
4435 | CondStatement ${ $0 = $<1; }$
4437 ###### declare terminals
4438 $TERM for then while do
4445 // A CondStatement must end with EOL, as does CondSuffix and
4447 // ForPart, ThenPart, SwitchPart, CasePart are non-empty and
4448 // may or may not end with EOL
4449 // WhilePart and IfPart include an appropriate Suffix
4451 // ForPart, SwitchPart, and IfPart open scopes, o we have to close
4452 // them. WhilePart opens and closes its own scope.
4453 CondStatement -> ForPart OptNL ThenPart OptNL WhilePart CondSuffix ${
4456 $0->thenpart = $<TP;
4457 $0->looppart = $<WP;
4458 var_block_close(c, CloseSequential, $0);
4460 | ForPart OptNL WhilePart CondSuffix ${
4463 $0->looppart = $<WP;
4464 var_block_close(c, CloseSequential, $0);
4466 | WhilePart CondSuffix ${
4468 $0->looppart = $<WP;
4470 | SwitchPart OptNL CasePart CondSuffix ${
4472 $0->condpart = $<SP;
4473 $CP->next = $0->casepart;
4474 $0->casepart = $<CP;
4475 var_block_close(c, CloseSequential, $0);
4477 | SwitchPart : IN OptNL CasePart CondSuffix OUT Newlines ${
4479 $0->condpart = $<SP;
4480 $CP->next = $0->casepart;
4481 $0->casepart = $<CP;
4482 var_block_close(c, CloseSequential, $0);
4484 | IfPart IfSuffix ${
4486 $0->condpart = $IP.condpart; $IP.condpart = NULL;
4487 $0->thenpart = $IP.thenpart; $IP.thenpart = NULL;
4488 // This is where we close an "if" statement
4489 var_block_close(c, CloseSequential, $0);
4492 CondSuffix -> IfSuffix ${
4495 | Newlines CasePart CondSuffix ${
4497 $CP->next = $0->casepart;
4498 $0->casepart = $<CP;
4500 | CasePart CondSuffix ${
4502 $CP->next = $0->casepart;
4503 $0->casepart = $<CP;
4506 IfSuffix -> Newlines ${ $0 = new(cond_statement); }$
4507 | Newlines ElsePart ${ $0 = $<EP; }$
4508 | ElsePart ${$0 = $<EP; }$
4510 ElsePart -> else OpenBlock Newlines ${
4511 $0 = new(cond_statement);
4512 $0->elsepart = $<OB;
4513 var_block_close(c, CloseElse, $0->elsepart);
4515 | else OpenScope CondStatement ${
4516 $0 = new(cond_statement);
4517 $0->elsepart = $<CS;
4518 var_block_close(c, CloseElse, $0->elsepart);
4522 CasePart -> case Expression OpenScope ColonBlock ${
4523 $0 = calloc(1,sizeof(struct casepart));
4526 var_block_close(c, CloseParallel, $0->action);
4530 // These scopes are closed in CondStatement
4531 ForPart -> for OpenBlock ${
4535 ThenPart -> then OpenBlock ${
4537 var_block_close(c, CloseSequential, $0);
4541 // This scope is closed in CondStatement
4542 WhilePart -> while UseBlock OptNL do OpenBlock ${
4547 var_block_close(c, CloseSequential, $0->right);
4548 var_block_close(c, CloseSequential, $0);
4550 | while OpenScope Expression OpenScope ColonBlock ${
4555 var_block_close(c, CloseSequential, $0->right);
4556 var_block_close(c, CloseSequential, $0);
4560 IfPart -> if UseBlock OptNL then OpenBlock ${
4563 var_block_close(c, CloseParallel, $0.thenpart);
4565 | if OpenScope Expression OpenScope ColonBlock ${
4568 var_block_close(c, CloseParallel, $0.thenpart);
4570 | if OpenScope Expression OpenScope OptNL then Block ${
4573 var_block_close(c, CloseParallel, $0.thenpart);
4577 // This scope is closed in CondStatement
4578 SwitchPart -> switch OpenScope Expression ${
4581 | switch UseBlock ${
4585 ###### print binode cases
4587 if (b->left && b->left->type == Xbinode &&
4588 cast(binode, b->left)->op == Block) {
4590 do_indent(indent, "while {\n");
4592 do_indent(indent, "while\n");
4593 print_exec(b->left, indent+1, bracket);
4595 do_indent(indent, "} do {\n");
4597 do_indent(indent, "do\n");
4598 print_exec(b->right, indent+1, bracket);
4600 do_indent(indent, "}\n");
4602 do_indent(indent, "while ");
4603 print_exec(b->left, 0, bracket);
4608 print_exec(b->right, indent+1, bracket);
4610 do_indent(indent, "}\n");
4614 ###### print exec cases
4616 case Xcond_statement:
4618 struct cond_statement *cs = cast(cond_statement, e);
4619 struct casepart *cp;
4621 do_indent(indent, "for");
4622 if (bracket) printf(" {\n"); else printf("\n");
4623 print_exec(cs->forpart, indent+1, bracket);
4626 do_indent(indent, "} then {\n");
4628 do_indent(indent, "then\n");
4629 print_exec(cs->thenpart, indent+1, bracket);
4631 if (bracket) do_indent(indent, "}\n");
4634 print_exec(cs->looppart, indent, bracket);
4638 do_indent(indent, "switch");
4640 do_indent(indent, "if");
4641 if (cs->condpart && cs->condpart->type == Xbinode &&
4642 cast(binode, cs->condpart)->op == Block) {
4647 print_exec(cs->condpart, indent+1, bracket);
4649 do_indent(indent, "}\n");
4651 do_indent(indent, "then\n");
4652 print_exec(cs->thenpart, indent+1, bracket);
4656 print_exec(cs->condpart, 0, bracket);
4662 print_exec(cs->thenpart, indent+1, bracket);
4664 do_indent(indent, "}\n");
4669 for (cp = cs->casepart; cp; cp = cp->next) {
4670 do_indent(indent, "case ");
4671 print_exec(cp->value, -1, 0);
4676 print_exec(cp->action, indent+1, bracket);
4678 do_indent(indent, "}\n");
4681 do_indent(indent, "else");
4686 print_exec(cs->elsepart, indent+1, bracket);
4688 do_indent(indent, "}\n");
4693 ###### propagate binode cases
4695 t = propagate_types(b->right, c, perr, Tnone, 0);
4696 if (!type_compat(Tnone, t, 0))
4697 *perr |= Efail; // UNTESTED
4698 return propagate_types(b->left, c, perr, type, rules);
4700 ###### propagate exec cases
4701 case Xcond_statement:
4703 // forpart and looppart->right must return Tnone
4704 // thenpart must return Tnone if there is a loopart,
4705 // otherwise it is like elsepart.
4707 // be bool if there is no casepart
4708 // match casepart->values if there is a switchpart
4709 // either be bool or match casepart->value if there
4711 // elsepart and casepart->action must match the return type
4712 // expected of this statement.
4713 struct cond_statement *cs = cast(cond_statement, prog);
4714 struct casepart *cp;
4716 t = propagate_types(cs->forpart, c, perr, Tnone, 0);
4717 if (!type_compat(Tnone, t, 0))
4718 *perr |= Efail; // UNTESTED
4721 t = propagate_types(cs->thenpart, c, perr, Tnone, 0);
4722 if (!type_compat(Tnone, t, 0))
4723 *perr |= Efail; // UNTESTED
4725 if (cs->casepart == NULL) {
4726 propagate_types(cs->condpart, c, perr, Tbool, 0);
4727 propagate_types(cs->looppart, c, perr, Tbool, 0);
4729 /* Condpart must match case values, with bool permitted */
4731 for (cp = cs->casepart;
4732 cp && !t; cp = cp->next)
4733 t = propagate_types(cp->value, c, perr, NULL, 0);
4734 if (!t && cs->condpart)
4735 t = propagate_types(cs->condpart, c, perr, NULL, Rboolok); // UNTESTED
4736 if (!t && cs->looppart)
4737 t = propagate_types(cs->looppart, c, perr, NULL, Rboolok); // UNTESTED
4738 // Now we have a type (I hope) push it down
4740 for (cp = cs->casepart; cp; cp = cp->next)
4741 propagate_types(cp->value, c, perr, t, 0);
4742 propagate_types(cs->condpart, c, perr, t, Rboolok);
4743 propagate_types(cs->looppart, c, perr, t, Rboolok);
4746 // (if)then, else, and case parts must return expected type.
4747 if (!cs->looppart && !type)
4748 type = propagate_types(cs->thenpart, c, perr, NULL, rules);
4750 type = propagate_types(cs->elsepart, c, perr, NULL, rules);
4751 for (cp = cs->casepart;
4753 cp = cp->next) // UNTESTED
4754 type = propagate_types(cp->action, c, perr, NULL, rules); // UNTESTED
4757 propagate_types(cs->thenpart, c, perr, type, rules);
4758 propagate_types(cs->elsepart, c, perr, type, rules);
4759 for (cp = cs->casepart; cp ; cp = cp->next)
4760 propagate_types(cp->action, c, perr, type, rules);
4766 ###### interp binode cases
4768 // This just performs one iterration of the loop
4769 rv = interp_exec(c, b->left, &rvtype);
4770 if (rvtype == Tnone ||
4771 (rvtype == Tbool && rv.bool != 0))
4772 // rvtype is Tnone or Tbool, doesn't need to be freed
4773 interp_exec(c, b->right, NULL);
4776 ###### interp exec cases
4777 case Xcond_statement:
4779 struct value v, cnd;
4780 struct type *vtype, *cndtype;
4781 struct casepart *cp;
4782 struct cond_statement *cs = cast(cond_statement, e);
4785 interp_exec(c, cs->forpart, NULL);
4787 while ((cnd = interp_exec(c, cs->looppart, &cndtype)),
4788 cndtype == Tnone || (cndtype == Tbool && cnd.bool != 0))
4789 interp_exec(c, cs->thenpart, NULL);
4791 cnd = interp_exec(c, cs->condpart, &cndtype);
4792 if ((cndtype == Tnone ||
4793 (cndtype == Tbool && cnd.bool != 0))) {
4794 // cnd is Tnone or Tbool, doesn't need to be freed
4795 rv = interp_exec(c, cs->thenpart, &rvtype);
4796 // skip else (and cases)
4800 for (cp = cs->casepart; cp; cp = cp->next) {
4801 v = interp_exec(c, cp->value, &vtype);
4802 if (value_cmp(cndtype, vtype, &v, &cnd) == 0) {
4803 free_value(vtype, &v);
4804 free_value(cndtype, &cnd);
4805 rv = interp_exec(c, cp->action, &rvtype);
4808 free_value(vtype, &v);
4810 free_value(cndtype, &cnd);
4812 rv = interp_exec(c, cs->elsepart, &rvtype);
4819 ### Top level structure
4821 All the language elements so far can be used in various places. Now
4822 it is time to clarify what those places are.
4824 At the top level of a file there will be a number of declarations.
4825 Many of the things that can be declared haven't been described yet,
4826 such as functions, procedures, imports, and probably more.
4827 For now there are two sorts of things that can appear at the top
4828 level. They are predefined constants, `struct` types, and the `main`
4829 function. While the syntax will allow the `main` function to appear
4830 multiple times, that will trigger an error if it is actually attempted.
4832 The various declarations do not return anything. They store the
4833 various declarations in the parse context.
4835 ###### Parser: grammar
4838 Ocean -> OptNL DeclarationList
4840 ## declare terminals
4848 DeclarationList -> Declaration
4849 | DeclarationList Declaration
4851 Declaration -> ERROR Newlines ${
4852 tok_err(c, // UNTESTED
4853 "error: unhandled parse error", &$1);
4859 ## top level grammar
4863 ### The `const` section
4865 As well as being defined in with the code that uses them, constants can
4866 be declared at the top level. These have full-file scope, so they are
4867 always `InScope`, even before(!) they have been declared. The value of
4868 a top level constant can be given as an expression, and this is
4869 evaluated after parsing and before execution.
4871 A function call can be used to evaluate a constant, but it will not have
4872 access to any program state, once such statement becomes meaningful.
4873 e.g. arguments and filesystem will not be visible.
4875 Constants are defined in a section that starts with the reserved word
4876 `const` and then has a block with a list of assignment statements.
4877 For syntactic consistency, these must use the double-colon syntax to
4878 make it clear that they are constants. Type can also be given: if
4879 not, the type will be determined during analysis, as with other
4882 ###### parse context
4883 struct binode *constlist;
4885 ###### top level grammar
4889 DeclareConstant -> const { IN OptNL ConstList OUT OptNL } Newlines
4890 | const { SimpleConstList } Newlines
4891 | const IN OptNL ConstList OUT Newlines
4892 | const SimpleConstList Newlines
4894 ConstList -> ConstList SimpleConstLine
4897 SimpleConstList -> SimpleConstList ; Const
4901 SimpleConstLine -> SimpleConstList Newlines
4902 | ERROR Newlines ${ tok_err(c, "Syntax error in constant", &$1); }$
4905 CType -> Type ${ $0 = $<1; }$
4909 Const -> IDENTIFIER :: CType = Expression ${ {
4911 struct binode *bl, *bv;
4912 struct var *var = new_pos(var, $ID);
4914 v = var_decl(c, $ID.txt);
4916 v->where_decl = var;
4922 v = var_ref(c, $1.txt);
4923 tok_err(c, "error: name already declared", &$1);
4924 type_err(c, "info: this is where '%v' was first declared",
4925 v->where_decl, NULL, 0, NULL);
4936 bl->left = c->constlist;
4941 ###### core functions
4942 static void resolve_consts(struct parse_context *c)
4945 c->constlist = reorder_bilist(c->constlist);
4946 for (b = cast(binode, c->constlist); b;
4947 b = cast(binode, b->right)) {
4949 struct binode *vb = cast(binode, b->left);
4950 struct var *v = cast(var, vb->left);
4953 propagate_types(vb->right, c, &perr,
4955 } while (perr & Eretry);
4957 c->parse_error += 1;
4959 struct value res = interp_exec(
4960 c, vb->right, &v->var->type);
4961 global_alloc(c, v->var->type, v->var, &res);
4966 ###### print const decls
4971 for (b = cast(binode, context.constlist); b;
4972 b = cast(binode, b->right)) {
4973 struct binode *vb = cast(binode, b->left);
4974 struct var *vr = cast(var, vb->left);
4975 struct variable *v = vr->var;
4981 printf(" %.*s :: ", v->name->name.len, v->name->name.txt);
4982 type_print(v->type, stdout);
4984 print_exec(vb->right, -1, 0);
4989 ###### free const decls
4990 free_binode(context.constlist);
4992 ### Function declarations
4994 The code in an Ocean program is all stored in function declarations.
4995 One of the functions must be named `main` and it must accept an array of
4996 strings as a parameter - the command line arguments.
4998 As this is the top level, several things are handled a bit differently.
4999 The function is not interpreted by `interp_exec` as that isn't passed
5000 the argument list which the program requires. Similarly type analysis
5001 is a bit more interesting at this level.
5003 ###### ast functions
5005 static struct type *handle_results(struct parse_context *c,
5006 struct binode *results)
5008 /* Create a 'struct' type from the results list, which
5009 * is a list for 'struct var'
5011 struct type *t = add_anon_type(c, &structure_prototype,
5012 " function result");
5016 for (b = results; b; b = cast(binode, b->right))
5018 t->structure.nfields = cnt;
5019 t->structure.fields = calloc(cnt, sizeof(struct field));
5021 for (b = results; b; b = cast(binode, b->right)) {
5022 struct var *v = cast(var, b->left);
5023 struct field *f = &t->structure.fields[cnt++];
5024 int a = v->var->type->align;
5025 f->name = v->var->name->name;
5026 f->type = v->var->type;
5028 f->offset = t->size;
5029 v->var->frame_pos = f->offset;
5030 t->size += ((f->type->size - 1) | (a-1)) + 1;
5033 variable_unlink_exec(v->var);
5035 free_binode(results);
5039 static struct variable *declare_function(struct parse_context *c,
5040 struct variable *name,
5041 struct binode *args,
5043 struct binode *results,
5047 struct value fn = {.function = code};
5049 var_block_close(c, CloseFunction, code);
5050 t = add_anon_type(c, &function_prototype,
5051 "func %.*s", name->name->name.len,
5052 name->name->name.txt);
5054 t->function.params = reorder_bilist(args);
5056 ret = handle_results(c, reorder_bilist(results));
5057 t->function.inline_result = 1;
5058 t->function.local_size = ret->size;
5060 t->function.return_type = ret;
5061 global_alloc(c, t, name, &fn);
5062 name->type->function.scope = c->out_scope;
5067 var_block_close(c, CloseFunction, NULL);
5069 c->out_scope = NULL;
5073 ###### declare terminals
5076 ###### top level grammar
5079 DeclareFunction -> func FuncName ( OpenScope ArgsLine ) Block Newlines ${
5080 $0 = declare_function(c, $<FN, $<Ar, Tnone, NULL, $<Bl);
5082 | func FuncName IN OpenScope Args OUT OptNL do Block Newlines ${
5083 $0 = declare_function(c, $<FN, $<Ar, Tnone, NULL, $<Bl);
5085 | func FuncName NEWLINE OpenScope OptNL do Block Newlines ${
5086 $0 = declare_function(c, $<FN, NULL, Tnone, NULL, $<Bl);
5088 | func FuncName ( OpenScope ArgsLine ) : Type Block Newlines ${
5089 $0 = declare_function(c, $<FN, $<Ar, $<Ty, NULL, $<Bl);
5091 | func FuncName ( OpenScope ArgsLine ) : ( ArgsLine ) Block Newlines ${
5092 $0 = declare_function(c, $<FN, $<AL, NULL, $<AL2, $<Bl);
5094 | func FuncName IN OpenScope Args OUT OptNL return Type Newlines do Block Newlines ${
5095 $0 = declare_function(c, $<FN, $<Ar, $<Ty, NULL, $<Bl);
5097 | func FuncName NEWLINE OpenScope return Type Newlines do Block Newlines ${
5098 $0 = declare_function(c, $<FN, NULL, $<Ty, NULL, $<Bl);
5100 | func FuncName IN OpenScope Args OUT OptNL return IN Args OUT OptNL do Block Newlines ${
5101 $0 = declare_function(c, $<FN, $<Ar, NULL, $<Ar2, $<Bl);
5103 | func FuncName NEWLINE OpenScope return IN Args OUT OptNL do Block Newlines ${
5104 $0 = declare_function(c, $<FN, NULL, NULL, $<Ar, $<Bl);
5107 ###### print func decls
5112 while (target != 0) {
5114 for (v = context.in_scope; v; v=v->in_scope)
5115 if (v->depth == 0 && v->type && v->type->check_args) {
5124 struct value *val = var_value(&context, v);
5125 printf("func %.*s", v->name->name.len, v->name->name.txt);
5126 v->type->print_type_decl(v->type, stdout);
5128 print_exec(val->function, 0, brackets);
5130 print_value(v->type, val, stdout);
5131 printf("/* frame size %d */\n", v->type->function.local_size);
5137 ###### core functions
5139 static int analyse_funcs(struct parse_context *c)
5143 for (v = c->in_scope; v; v = v->in_scope) {
5147 if (v->depth != 0 || !v->type || !v->type->check_args)
5149 ret = v->type->function.inline_result ?
5150 Tnone : v->type->function.return_type;
5151 val = var_value(c, v);
5154 propagate_types(val->function, c, &perr, ret, 0);
5155 } while (!(perr & Efail) && (perr & Eretry));
5156 if (!(perr & Efail))
5157 /* Make sure everything is still consistent */
5158 propagate_types(val->function, c, &perr, ret, 0);
5161 if (!v->type->function.inline_result &&
5162 !v->type->function.return_type->dup) {
5163 type_err(c, "error: function cannot return value of type %1",
5164 v->where_decl, v->type->function.return_type, 0, NULL);
5167 scope_finalize(c, v->type);
5172 static int analyse_main(struct type *type, struct parse_context *c)
5174 struct binode *bp = type->function.params;
5178 struct type *argv_type;
5180 argv_type = add_anon_type(c, &array_prototype, "argv");
5181 argv_type->array.member = Tstr;
5182 argv_type->array.unspec = 1;
5184 for (b = bp; b; b = cast(binode, b->right)) {
5188 propagate_types(b->left, c, &perr, argv_type, 0);
5190 default: /* invalid */ // NOTEST
5191 propagate_types(b->left, c, &perr, Tnone, 0); // NOTEST
5194 c->parse_error += 1;
5197 return !c->parse_error;
5200 static void interp_main(struct parse_context *c, int argc, char **argv)
5202 struct value *progp = NULL;
5203 struct text main_name = { "main", 4 };
5204 struct variable *mainv;
5210 mainv = var_ref(c, main_name);
5212 progp = var_value(c, mainv);
5213 if (!progp || !progp->function) {
5214 fprintf(stderr, "oceani: no main function found.\n");
5215 c->parse_error += 1;
5218 if (!analyse_main(mainv->type, c)) {
5219 fprintf(stderr, "oceani: main has wrong type.\n");
5220 c->parse_error += 1;
5223 al = mainv->type->function.params;
5225 c->local_size = mainv->type->function.local_size;
5226 c->local = calloc(1, c->local_size);
5228 struct var *v = cast(var, al->left);
5229 struct value *vl = var_value(c, v->var);
5239 mpq_set_ui(argcq, argc, 1);
5240 memcpy(var_value(c, t->array.vsize), &argcq, sizeof(argcq));
5241 t->prepare_type(c, t, 0);
5242 array_init(v->var->type, vl);
5243 for (i = 0; i < argc; i++) {
5244 struct value *vl2 = vl->array + i * v->var->type->array.member->size;
5246 arg.str.txt = argv[i];
5247 arg.str.len = strlen(argv[i]);
5248 free_value(Tstr, vl2);
5249 dup_value(Tstr, &arg, vl2);
5253 al = cast(binode, al->right);
5255 v = interp_exec(c, progp->function, &vtype);
5256 free_value(vtype, &v);
5261 ###### ast functions
5262 void free_variable(struct variable *v)
5266 ## And now to test it out.
5268 Having a language requires having a "hello world" program. I'll
5269 provide a little more than that: a program that prints "Hello world"
5270 finds the GCD of two numbers, prints the first few elements of
5271 Fibonacci, performs a binary search for a number, and a few other
5272 things which will likely grow as the languages grows.
5274 ###### File: oceani.mk
5277 @echo "===== DEMO ====="
5278 ./oceani --section "demo: hello" oceani.mdc 55 33
5284 four ::= 2 + 2 ; five ::= 10/2
5285 const pie ::= "I like Pie";
5286 cake ::= "The cake is"
5294 func main(argv:[argc::]string)
5295 print "Hello World, what lovely oceans you have!"
5296 print "Are there", five, "?"
5297 print pi, pie, "but", cake
5299 A := $argv[1]; B := $argv[2]
5301 /* When a variable is defined in both branches of an 'if',
5302 * and used afterwards, the variables are merged.
5308 print "Is", A, "bigger than", B,"? ", bigger
5309 /* If a variable is not used after the 'if', no
5310 * merge happens, so types can be different
5313 double:string = "yes"
5314 print A, "is more than twice", B, "?", double
5317 print "double", B, "is", double
5322 if a > 0 and then b > 0:
5328 print "GCD of", A, "and", B,"is", a
5330 print a, "is not positive, cannot calculate GCD"
5332 print b, "is not positive, cannot calculate GCD"
5337 print "Fibonacci:", f1,f2,
5338 then togo = togo - 1
5346 /* Binary search... */
5351 mid := (lo + hi) / 2
5364 print "Yay, I found", target
5366 print "Closest I found was", lo
5371 // "middle square" PRNG. Not particularly good, but one my
5372 // Dad taught me - the first one I ever heard of.
5373 for i:=1; then i = i + 1; while i < size:
5374 n := list[i-1] * list[i-1]
5375 list[i] = (n / 100) % 10 000
5377 print "Before sort:",
5378 for i:=0; then i = i + 1; while i < size:
5382 for i := 1; then i=i+1; while i < size:
5383 for j:=i-1; then j=j-1; while j >= 0:
5384 if list[j] > list[j+1]:
5388 print " After sort:",
5389 for i:=0; then i = i + 1; while i < size:
5393 if 1 == 2 then print "yes"; else print "no"
5397 bob.alive = (bob.name == "Hello")
5398 print "bob", "is" if bob.alive else "isn't", "alive"