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 if (!context.parse_error && !analyse_funcs(&context)) {
246 fprintf(stderr, "oceani: type error in program - not running.\n");
247 context.parse_error = 1;
255 if (doexec && !context.parse_error)
256 interp_main(&context, argc - optind, argv + optind);
259 struct section *t = s->next;
264 // FIXME parser should pop scope even on error
265 while (context.scope_depth > 0)
268 ## free context types
269 ## free context storage
270 exit(context.parse_error ? 1 : 0);
275 The four requirements of parse, analyse, print, interpret apply to
276 each language element individually so that is how most of the code
279 Three of the four are fairly self explanatory. The one that requires
280 a little explanation is the analysis step.
282 The current language design does not require the types of variables to
283 be declared, but they must still have a single type. Different
284 operations impose different requirements on the variables, for example
285 addition requires both arguments to be numeric, and assignment
286 requires the variable on the left to have the same type as the
287 expression on the right.
289 Analysis involves propagating these type requirements around and
290 consequently setting the type of each variable. If any requirements
291 are violated (e.g. a string is compared with a number) or if a
292 variable needs to have two different types, then an error is raised
293 and the program will not run.
295 If the same variable is declared in both branchs of an 'if/else', or
296 in all cases of a 'switch' then the multiple instances may be merged
297 into just one variable if the variable is referenced after the
298 conditional statement. When this happens, the types must naturally be
299 consistent across all the branches. When the variable is not used
300 outside the if, the variables in the different branches are distinct
301 and can be of different types.
303 Undeclared names may only appear in "use" statements and "case" expressions.
304 These names are given a type of "label" and a unique value.
305 This allows them to fill the role of a name in an enumerated type, which
306 is useful for testing the `switch` statement.
308 As we will see, the condition part of a `while` statement can return
309 either a Boolean or some other type. This requires that the expected
310 type that gets passed around comprises a type and a flag to indicate
311 that `Tbool` is also permitted.
313 As there are, as yet, no distinct types that are compatible, there
314 isn't much subtlety in the analysis. When we have distinct number
315 types, this will become more interesting.
319 When analysis discovers an inconsistency it needs to report an error;
320 just refusing to run the code ensures that the error doesn't cascade,
321 but by itself it isn't very useful. A clear understanding of the sort
322 of error message that are useful will help guide the process of
325 At a simplistic level, the only sort of error that type analysis can
326 report is that the type of some construct doesn't match a contextual
327 requirement. For example, in `4 + "hello"` the addition provides a
328 contextual requirement for numbers, but `"hello"` is not a number. In
329 this particular example no further information is needed as the types
330 are obvious from local information. When a variable is involved that
331 isn't the case. It may be helpful to explain why the variable has a
332 particular type, by indicating the location where the type was set,
333 whether by declaration or usage.
335 Using a recursive-descent analysis we can easily detect a problem at
336 multiple locations. In "`hello:= "there"; 4 + hello`" the addition
337 will detect that one argument is not a number and the usage of `hello`
338 will detect that a number was wanted, but not provided. In this
339 (early) version of the language, we will generate error reports at
340 multiple locations, so the use of `hello` will report an error and
341 explain were the value was set, and the addition will report an error
342 and say why numbers are needed. To be able to report locations for
343 errors, each language element will need to record a file location
344 (line and column) and each variable will need to record the language
345 element where its type was set. For now we will assume that each line
346 of an error message indicates one location in the file, and up to 2
347 types. So we provide a `printf`-like function which takes a format, a
348 location (a `struct exec` which has not yet been introduced), and 2
349 types. "`%1`" reports the first type, "`%2`" reports the second. We
350 will need a function to print the location, once we know how that is
351 stored. e As will be explained later, there are sometimes extra rules for
352 type matching and they might affect error messages, we need to pass those
355 As well as type errors, we sometimes need to report problems with
356 tokens, which might be unexpected or might name a type that has not
357 been defined. For these we have `tok_err()` which reports an error
358 with a given token. Each of the error functions sets the flag in the
359 context so indicate that parsing failed.
363 static void fput_loc(struct exec *loc, FILE *f);
364 static void type_err(struct parse_context *c,
365 char *fmt, struct exec *loc,
366 struct type *t1, int rules, struct type *t2);
368 ###### core functions
370 static void type_err(struct parse_context *c,
371 char *fmt, struct exec *loc,
372 struct type *t1, int rules, struct type *t2)
374 fprintf(stderr, "%s:", c->file_name);
375 fput_loc(loc, stderr);
376 for (; *fmt ; fmt++) {
383 case '%': fputc(*fmt, stderr); break; // NOTEST
384 default: fputc('?', stderr); break; // NOTEST
386 type_print(t1, stderr);
389 type_print(t2, stderr);
398 static void tok_err(struct parse_context *c, char *fmt, struct token *t)
400 fprintf(stderr, "%s:%d:%d: %s: %.*s\n", c->file_name, t->line, t->col, fmt,
401 t->txt.len, t->txt.txt);
405 ## Entities: declared and predeclared.
407 There are various "things" that the language and/or the interpreter
408 needs to know about to parse and execute a program. These include
409 types, variables, values, and executable code. These are all lumped
410 together under the term "entities" (calling them "objects" would be
411 confusing) and introduced here. The following section will present the
412 different specific code elements which comprise or manipulate these
417 Executables can be lots of different things. In many cases an
418 executable is just an operation combined with one or two other
419 executables. This allows for expressions and lists etc. Other times an
420 executable is something quite specific like a constant or variable name.
421 So we define a `struct exec` to be a general executable with a type, and
422 a `struct binode` which is a subclass of `exec`, forms a node in a
423 binary tree, and holds an operation. There will be other subclasses,
424 and to access these we need to be able to `cast` the `exec` into the
425 various other types. The first field in any `struct exec` is the type
426 from the `exec_types` enum.
429 #define cast(structname, pointer) ({ \
430 const typeof( ((struct structname *)0)->type) *__mptr = &(pointer)->type; \
431 if (__mptr && *__mptr != X##structname) abort(); \
432 (struct structname *)( (char *)__mptr);})
434 #define new(structname) ({ \
435 struct structname *__ptr = ((struct structname *)calloc(1,sizeof(struct structname))); \
436 __ptr->type = X##structname; \
437 __ptr->line = -1; __ptr->column = -1; \
440 #define new_pos(structname, token) ({ \
441 struct structname *__ptr = ((struct structname *)calloc(1,sizeof(struct structname))); \
442 __ptr->type = X##structname; \
443 __ptr->line = token.line; __ptr->column = token.col; \
452 enum exec_types type;
461 struct exec *left, *right;
466 static int __fput_loc(struct exec *loc, FILE *f)
470 if (loc->line >= 0) {
471 fprintf(f, "%d:%d: ", loc->line, loc->column);
474 if (loc->type == Xbinode)
475 return __fput_loc(cast(binode,loc)->left, f) ||
476 __fput_loc(cast(binode,loc)->right, f); // NOTEST
479 static void fput_loc(struct exec *loc, FILE *f)
481 if (!__fput_loc(loc, f))
482 fprintf(f, "??:??: ");
485 Each different type of `exec` node needs a number of functions defined,
486 a bit like methods. We must be able to free it, print it, analyse it
487 and execute it. Once we have specific `exec` types we will need to
488 parse them too. Let's take this a bit more slowly.
492 The parser generator requires a `free_foo` function for each struct
493 that stores attributes and they will often be `exec`s and subtypes
494 there-of. So we need `free_exec` which can handle all the subtypes,
495 and we need `free_binode`.
499 static void free_binode(struct binode *b)
508 ###### core functions
509 static void free_exec(struct exec *e)
520 static void free_exec(struct exec *e);
522 ###### free exec cases
523 case Xbinode: free_binode(cast(binode, e)); break;
527 Printing an `exec` requires that we know the current indent level for
528 printing line-oriented components. As will become clear later, we
529 also want to know what sort of bracketing to use.
533 static void do_indent(int i, char *str)
540 ###### core functions
541 static void print_binode(struct binode *b, int indent, int bracket)
545 ## print binode cases
549 static void print_exec(struct exec *e, int indent, int bracket)
555 print_binode(cast(binode, e), indent, bracket); break;
560 do_indent(indent, "/* FREE");
561 for (v = e->to_free; v; v = v->next_free) {
562 printf(" %.*s", v->name->name.len, v->name->name.txt);
563 printf("[%d,%d]", v->scope_start, v->scope_end);
564 if (v->frame_pos >= 0)
565 printf("(%d+%d)", v->frame_pos,
566 v->type ? v->type->size:0);
574 static void print_exec(struct exec *e, int indent, int bracket);
578 As discussed, analysis involves propagating type requirements around the
579 program and looking for errors.
581 So `propagate_types` is passed an expected type (being a `struct type`
582 pointer together with some `val_rules` flags) that the `exec` is
583 expected to return, and returns the type that it does return, either
584 of which can be `NULL` signifying "unknown". An `ok` flag is passed
585 by reference. It is set to `0` when an error is found, and `2` when
586 any change is made. If it remains unchanged at `1`, then no more
587 propagation is needed.
591 enum val_rules {Rnolabel = 1<<0, Rboolok = 1<<1, Rnoconstant = 1<<2};
595 if (rules & Rnolabel)
596 fputs(" (labels not permitted)", stderr);
600 static struct type *propagate_types(struct exec *prog, struct parse_context *c, int *ok,
601 struct type *type, int rules);
602 ###### core functions
604 static struct type *__propagate_types(struct exec *prog, struct parse_context *c, int *ok,
605 struct type *type, int rules)
612 switch (prog->type) {
615 struct binode *b = cast(binode, prog);
617 ## propagate binode cases
621 ## propagate exec cases
626 static struct type *propagate_types(struct exec *prog, struct parse_context *c, int *ok,
627 struct type *type, int rules)
629 struct type *ret = __propagate_types(prog, c, ok, type, rules);
638 Interpreting an `exec` doesn't require anything but the `exec`. State
639 is stored in variables and each variable will be directly linked from
640 within the `exec` tree. The exception to this is the `main` function
641 which needs to look at command line arguments. This function will be
642 interpreted separately.
644 Each `exec` can return a value combined with a type in `struct lrval`.
645 The type may be `Tnone` but must be non-NULL. Some `exec`s will return
646 the location of a value, which can be updated, in `lval`. Others will
647 set `lval` to NULL indicating that there is a value of appropriate type
650 ###### core functions
654 struct value rval, *lval;
657 /* If dest is passed, dtype must give the expected type, and
658 * result can go there, in which case type is returned as NULL.
660 static struct lrval _interp_exec(struct parse_context *c, struct exec *e,
661 struct value *dest, struct type *dtype);
663 static struct value interp_exec(struct parse_context *c, struct exec *e,
664 struct type **typeret)
666 struct lrval ret = _interp_exec(c, e, NULL, NULL);
668 if (!ret.type) abort();
672 dup_value(ret.type, ret.lval, &ret.rval);
676 static struct value *linterp_exec(struct parse_context *c, struct exec *e,
677 struct type **typeret)
679 struct lrval ret = _interp_exec(c, e, NULL, NULL);
681 if (!ret.type) abort();
685 free_value(ret.type, &ret.rval);
689 /* dinterp_exec is used when the destination type is certain and
690 * the value has a place to go.
692 static void dinterp_exec(struct parse_context *c, struct exec *e,
693 struct value *dest, struct type *dtype,
696 struct lrval ret = _interp_exec(c, e, dest, dtype);
700 free_value(dtype, dest);
702 dup_value(dtype, ret.lval, dest);
704 memcpy(dest, &ret.rval, dtype->size);
707 static struct lrval _interp_exec(struct parse_context *c, struct exec *e,
708 struct value *dest, struct type *dtype)
710 /* If the result is copied to dest, ret.type is set to NULL */
712 struct value rv = {}, *lrv = NULL;
715 rvtype = ret.type = Tnone;
725 struct binode *b = cast(binode, e);
726 struct value left, right, *lleft;
727 struct type *ltype, *rtype;
728 ltype = rtype = Tnone;
730 ## interp binode cases
732 free_value(ltype, &left);
733 free_value(rtype, &right);
743 ## interp exec cleanup
749 Values come in a wide range of types, with more likely to be added.
750 Each type needs to be able to print its own values (for convenience at
751 least) as well as to compare two values, at least for equality and
752 possibly for order. For now, values might need to be duplicated and
753 freed, though eventually such manipulations will be better integrated
756 Rather than requiring every numeric type to support all numeric
757 operations (add, multiply, etc), we allow types to be able to present
758 as one of a few standard types: integer, float, and fraction. The
759 existence of these conversion functions eventually enable types to
760 determine if they are compatible with other types, though such types
761 have not yet been implemented.
763 Named type are stored in a simple linked list. Objects of each type are
764 "values" which are often passed around by value.
766 There are both explicitly named types, and anonymous types. Anonymous
767 cannot be accessed by name, but are used internally and have a name
768 which might be reported in error messages.
775 ## value union fields
784 void (*init)(struct type *type, struct value *val);
785 void (*prepare_type)(struct parse_context *c, struct type *type, int parse_time);
786 void (*print)(struct type *type, struct value *val, FILE *f);
787 void (*print_type)(struct type *type, FILE *f);
788 int (*cmp_order)(struct type *t1, struct type *t2,
789 struct value *v1, struct value *v2);
790 int (*cmp_eq)(struct type *t1, struct type *t2,
791 struct value *v1, struct value *v2);
792 void (*dup)(struct type *type, struct value *vold, struct value *vnew);
793 void (*free)(struct type *type, struct value *val);
794 void (*free_type)(struct type *t);
795 long long (*to_int)(struct value *v);
796 double (*to_float)(struct value *v);
797 int (*to_mpq)(mpq_t *q, struct value *v);
806 struct type *typelist;
813 static struct type *find_type(struct parse_context *c, struct text s)
815 struct type *t = c->typelist;
817 while (t && (t->anon ||
818 text_cmp(t->name, s) != 0))
823 static struct type *_add_type(struct parse_context *c, struct text s,
824 struct type *proto, int anon)
828 n = calloc(1, sizeof(*n));
832 n->next = c->typelist;
837 static struct type *add_type(struct parse_context *c, struct text s,
840 return _add_type(c, s, proto, 0);
843 static struct type *add_anon_type(struct parse_context *c,
844 struct type *proto, char *name, ...)
850 vasprintf(&t.txt, name, ap);
852 t.len = strlen(name);
853 return _add_type(c, t, proto, 1);
856 static void free_type(struct type *t)
858 /* The type is always a reference to something in the
859 * context, so we don't need to free anything.
863 static void free_value(struct type *type, struct value *v)
867 memset(v, 0x5a, type->size);
871 static void type_print(struct type *type, FILE *f)
874 fputs("*unknown*type*", f); // NOTEST
875 else if (type->name.len && !type->anon)
876 fprintf(f, "%.*s", type->name.len, type->name.txt);
877 else if (type->print_type)
878 type->print_type(type, f);
880 fputs("*invalid*type*", f);
883 static void val_init(struct type *type, struct value *val)
885 if (type && type->init)
886 type->init(type, val);
889 static void dup_value(struct type *type,
890 struct value *vold, struct value *vnew)
892 if (type && type->dup)
893 type->dup(type, vold, vnew);
896 static int value_cmp(struct type *tl, struct type *tr,
897 struct value *left, struct value *right)
899 if (tl && tl->cmp_order)
900 return tl->cmp_order(tl, tr, left, right);
901 if (tl && tl->cmp_eq) // NOTEST
902 return tl->cmp_eq(tl, tr, left, right); // NOTEST
906 static void print_value(struct type *type, struct value *v, FILE *f)
908 if (type && type->print)
909 type->print(type, v, f);
911 fprintf(f, "*Unknown*"); // NOTEST
916 static void free_value(struct type *type, struct value *v);
917 static int type_compat(struct type *require, struct type *have, int rules);
918 static void type_print(struct type *type, FILE *f);
919 static void val_init(struct type *type, struct value *v);
920 static void dup_value(struct type *type,
921 struct value *vold, struct value *vnew);
922 static int value_cmp(struct type *tl, struct type *tr,
923 struct value *left, struct value *right);
924 static void print_value(struct type *type, struct value *v, FILE *f);
926 ###### free context types
928 while (context.typelist) {
929 struct type *t = context.typelist;
931 context.typelist = t->next;
939 Type can be specified for local variables, for fields in a structure,
940 for formal parameters to functions, and possibly elsewhere. Different
941 rules may apply in different contexts. As a minimum, a named type may
942 always be used. Currently the type of a formal parameter can be
943 different from types in other contexts, so we have a separate grammar
949 Type -> IDENTIFIER ${
950 $0 = find_type(c, $1.txt);
953 "error: undefined type", &$1);
960 FormalType -> Type ${ $0 = $<1; }$
961 ## formal type grammar
965 Values of the base types can be numbers, which we represent as
966 multi-precision fractions, strings, Booleans and labels. When
967 analysing the program we also need to allow for places where no value
968 is meaningful (type `Tnone`) and where we don't know what type to
969 expect yet (type is `NULL`).
971 Values are never shared, they are always copied when used, and freed
972 when no longer needed.
974 When propagating type information around the program, we need to
975 determine if two types are compatible, where type `NULL` is compatible
976 with anything. There are two special cases with type compatibility,
977 both related to the Conditional Statement which will be described
978 later. In some cases a Boolean can be accepted as well as some other
979 primary type, and in others any type is acceptable except a label (`Vlabel`).
980 A separate function encoding these cases will simplify some code later.
982 ###### type functions
984 int (*compat)(struct type *this, struct type *other);
988 static int type_compat(struct type *require, struct type *have, int rules)
990 if ((rules & Rboolok) && have == Tbool)
992 if ((rules & Rnolabel) && have == Tlabel)
994 if (!require || !have)
998 return require->compat(require, have);
1000 return require == have;
1005 #include "parse_string.h"
1006 #include "parse_number.h"
1009 myLDLIBS := libnumber.o libstring.o -lgmp
1010 LDLIBS := $(filter-out $(myLDLIBS),$(LDLIBS)) $(myLDLIBS)
1012 ###### type union fields
1013 enum vtype {Vnone, Vstr, Vnum, Vbool, Vlabel} vtype;
1015 ###### value union fields
1021 ###### ast functions
1022 static void _free_value(struct type *type, struct value *v)
1026 switch (type->vtype) {
1028 case Vstr: free(v->str.txt); break;
1029 case Vnum: mpq_clear(v->num); break;
1035 ###### value functions
1037 static void _val_init(struct type *type, struct value *val)
1039 switch(type->vtype) {
1040 case Vnone: // NOTEST
1043 mpq_init(val->num); break;
1045 val->str.txt = malloc(1);
1057 static void _dup_value(struct type *type,
1058 struct value *vold, struct value *vnew)
1060 switch (type->vtype) {
1061 case Vnone: // NOTEST
1064 vnew->label = vold->label;
1067 vnew->bool = vold->bool;
1070 mpq_init(vnew->num);
1071 mpq_set(vnew->num, vold->num);
1074 vnew->str.len = vold->str.len;
1075 vnew->str.txt = malloc(vnew->str.len);
1076 memcpy(vnew->str.txt, vold->str.txt, vnew->str.len);
1081 static int _value_cmp(struct type *tl, struct type *tr,
1082 struct value *left, struct value *right)
1086 return tl - tr; // NOTEST
1087 switch (tl->vtype) {
1088 case Vlabel: cmp = left->label == right->label ? 0 : 1; break;
1089 case Vnum: cmp = mpq_cmp(left->num, right->num); break;
1090 case Vstr: cmp = text_cmp(left->str, right->str); break;
1091 case Vbool: cmp = left->bool - right->bool; break;
1092 case Vnone: cmp = 0; // NOTEST
1097 static void _print_value(struct type *type, struct value *v, FILE *f)
1099 switch (type->vtype) {
1100 case Vnone: // NOTEST
1101 fprintf(f, "*no-value*"); break; // NOTEST
1102 case Vlabel: // NOTEST
1103 fprintf(f, "*label-%p*", v->label); break; // NOTEST
1105 fprintf(f, "%.*s", v->str.len, v->str.txt); break;
1107 fprintf(f, "%s", v->bool ? "True":"False"); break;
1112 mpf_set_q(fl, v->num);
1113 gmp_fprintf(f, "%Fg", fl);
1120 static void _free_value(struct type *type, struct value *v);
1122 static struct type base_prototype = {
1124 .print = _print_value,
1125 .cmp_order = _value_cmp,
1126 .cmp_eq = _value_cmp,
1128 .free = _free_value,
1131 static struct type *Tbool, *Tstr, *Tnum, *Tnone, *Tlabel;
1133 ###### ast functions
1134 static struct type *add_base_type(struct parse_context *c, char *n,
1135 enum vtype vt, int size)
1137 struct text txt = { n, strlen(n) };
1140 t = add_type(c, txt, &base_prototype);
1143 t->align = size > sizeof(void*) ? sizeof(void*) : size;
1144 if (t->size & (t->align - 1))
1145 t->size = (t->size | (t->align - 1)) + 1; // NOTEST
1149 ###### context initialization
1151 Tbool = add_base_type(&context, "Boolean", Vbool, sizeof(char));
1152 Tstr = add_base_type(&context, "string", Vstr, sizeof(struct text));
1153 Tnum = add_base_type(&context, "number", Vnum, sizeof(mpq_t));
1154 Tnone = add_base_type(&context, "none", Vnone, 0);
1155 Tlabel = add_base_type(&context, "label", Vlabel, sizeof(void*));
1159 We have already met values as separate objects. When manifest constants
1160 appear in the program text, that must result in an executable which has
1161 a constant value. So the `val` structure embeds a value in an
1174 ###### ast functions
1175 struct val *new_val(struct type *T, struct token tk)
1177 struct val *v = new_pos(val, tk);
1188 $0 = new_val(Tbool, $1);
1192 $0 = new_val(Tbool, $1);
1197 $0 = new_val(Tnum, $1);
1198 if (number_parse($0->val.num, tail, $1.txt) == 0)
1199 mpq_init($0->val.num); // UNTESTED
1201 tok_err(c, "error: unsupported number suffix",
1206 $0 = new_val(Tstr, $1);
1207 string_parse(&$1, '\\', &$0->val.str, tail);
1209 tok_err(c, "error: unsupported string suffix",
1214 $0 = new_val(Tstr, $1);
1215 string_parse(&$1, '\\', &$0->val.str, tail);
1217 tok_err(c, "error: unsupported string suffix",
1221 ###### print exec cases
1224 struct val *v = cast(val, e);
1225 if (v->vtype == Tstr)
1227 print_value(v->vtype, &v->val, stdout);
1228 if (v->vtype == Tstr)
1233 ###### propagate exec cases
1236 struct val *val = cast(val, prog);
1237 if (!type_compat(type, val->vtype, rules))
1238 type_err(c, "error: expected %1%r found %2",
1239 prog, type, rules, val->vtype);
1243 ###### interp exec cases
1245 rvtype = cast(val, e)->vtype;
1246 dup_value(rvtype, &cast(val, e)->val, &rv);
1249 ###### ast functions
1250 static void free_val(struct val *v)
1253 free_value(v->vtype, &v->val);
1257 ###### free exec cases
1258 case Xval: free_val(cast(val, e)); break;
1260 ###### ast functions
1261 // Move all nodes from 'b' to 'rv', reversing their order.
1262 // In 'b' 'left' is a list, and 'right' is the last node.
1263 // In 'rv', left' is the first node and 'right' is a list.
1264 static struct binode *reorder_bilist(struct binode *b)
1266 struct binode *rv = NULL;
1269 struct exec *t = b->right;
1273 b = cast(binode, b->left);
1283 Variables are scoped named values. We store the names in a linked list
1284 of "bindings" sorted in lexical order, and use sequential search and
1291 struct binding *next; // in lexical order
1295 This linked list is stored in the parse context so that "reduce"
1296 functions can find or add variables, and so the analysis phase can
1297 ensure that every variable gets a type.
1299 ###### parse context
1301 struct binding *varlist; // In lexical order
1303 ###### ast functions
1305 static struct binding *find_binding(struct parse_context *c, struct text s)
1307 struct binding **l = &c->varlist;
1312 (cmp = text_cmp((*l)->name, s)) < 0)
1316 n = calloc(1, sizeof(*n));
1323 Each name can be linked to multiple variables defined in different
1324 scopes. Each scope starts where the name is declared and continues
1325 until the end of the containing code block. Scopes of a given name
1326 cannot nest, so a declaration while a name is in-scope is an error.
1328 ###### binding fields
1329 struct variable *var;
1333 struct variable *previous;
1335 struct binding *name;
1336 struct exec *where_decl;// where name was declared
1337 struct exec *where_set; // where type was set
1341 When a scope closes, the values of the variables might need to be freed.
1342 This happens in the context of some `struct exec` and each `exec` will
1343 need to know which variables need to be freed when it completes.
1346 struct variable *to_free;
1348 ####### variable fields
1349 struct exec *cleanup_exec;
1350 struct variable *next_free;
1352 ####### interp exec cleanup
1355 for (v = e->to_free; v; v = v->next_free) {
1356 struct value *val = var_value(c, v);
1357 free_value(v->type, val);
1361 ###### ast functions
1362 static void variable_unlink_exec(struct variable *v)
1364 struct variable **vp;
1365 if (!v->cleanup_exec)
1367 for (vp = &v->cleanup_exec->to_free;
1368 *vp; vp = &(*vp)->next_free) {
1372 v->cleanup_exec = NULL;
1377 While the naming seems strange, we include local constants in the
1378 definition of variables. A name declared `var := value` can
1379 subsequently be changed, but a name declared `var ::= value` cannot -
1382 ###### variable fields
1385 Scopes in parallel branches can be partially merged. More
1386 specifically, if a given name is declared in both branches of an
1387 if/else then its scope is a candidate for merging. Similarly if
1388 every branch of an exhaustive switch (e.g. has an "else" clause)
1389 declares a given name, then the scopes from the branches are
1390 candidates for merging.
1392 Note that names declared inside a loop (which is only parallel to
1393 itself) are never visible after the loop. Similarly names defined in
1394 scopes which are not parallel, such as those started by `for` and
1395 `switch`, are never visible after the scope. Only variables defined in
1396 both `then` and `else` (including the implicit then after an `if`, and
1397 excluding `then` used with `for`) and in all `case`s and `else` of a
1398 `switch` or `while` can be visible beyond the `if`/`switch`/`while`.
1400 Labels, which are a bit like variables, follow different rules.
1401 Labels are not explicitly declared, but if an undeclared name appears
1402 in a context where a label is legal, that effectively declares the
1403 name as a label. The declaration remains in force (or in scope) at
1404 least to the end of the immediately containing block and conditionally
1405 in any larger containing block which does not declare the name in some
1406 other way. Importantly, the conditional scope extension happens even
1407 if the label is only used in one parallel branch of a conditional --
1408 when used in one branch it is treated as having been declared in all
1411 Merge candidates are tentatively visible beyond the end of the
1412 branching statement which creates them. If the name is used, the
1413 merge is affirmed and they become a single variable visible at the
1414 outer layer. If not - if it is redeclared first - the merge lapses.
1416 To track scopes we have an extra stack, implemented as a linked list,
1417 which roughly parallels the parse stack and which is used exclusively
1418 for scoping. When a new scope is opened, a new frame is pushed and
1419 the child-count of the parent frame is incremented. This child-count
1420 is used to distinguish between the first of a set of parallel scopes,
1421 in which declared variables must not be in scope, and subsequent
1422 branches, whether they may already be conditionally scoped.
1424 We need a total ordering of scopes so we can easily compare to variables
1425 to see if they are concurrently in scope. To achieve this we record a
1426 `scope_count` which is actually a count of both beginnings and endings
1427 of scopes. Then each variable has a record of the scope count where it
1428 enters scope, and where it leaves.
1430 To push a new frame *before* any code in the frame is parsed, we need a
1431 grammar reduction. This is most easily achieved with a grammar
1432 element which derives the empty string, and creates the new scope when
1433 it is recognised. This can be placed, for example, between a keyword
1434 like "if" and the code following it.
1438 struct scope *parent;
1442 ###### parse context
1445 struct scope *scope_stack;
1447 ###### variable fields
1448 int scope_start, scope_end;
1450 ###### ast functions
1451 static void scope_pop(struct parse_context *c)
1453 struct scope *s = c->scope_stack;
1455 c->scope_stack = s->parent;
1457 c->scope_depth -= 1;
1458 c->scope_count += 1;
1461 static void scope_push(struct parse_context *c)
1463 struct scope *s = calloc(1, sizeof(*s));
1465 c->scope_stack->child_count += 1;
1466 s->parent = c->scope_stack;
1468 c->scope_depth += 1;
1469 c->scope_count += 1;
1475 OpenScope -> ${ scope_push(c); }$
1477 Each variable records a scope depth and is in one of four states:
1479 - "in scope". This is the case between the declaration of the
1480 variable and the end of the containing block, and also between
1481 the usage with affirms a merge and the end of that block.
1483 The scope depth is not greater than the current parse context scope
1484 nest depth. When the block of that depth closes, the state will
1485 change. To achieve this, all "in scope" variables are linked
1486 together as a stack in nesting order.
1488 - "pending". The "in scope" block has closed, but other parallel
1489 scopes are still being processed. So far, every parallel block at
1490 the same level that has closed has declared the name.
1492 The scope depth is the depth of the last parallel block that
1493 enclosed the declaration, and that has closed.
1495 - "conditionally in scope". The "in scope" block and all parallel
1496 scopes have closed, and no further mention of the name has been seen.
1497 This state includes a secondary nest depth (`min_depth`) which records
1498 the outermost scope seen since the variable became conditionally in
1499 scope. If a use of the name is found, the variable becomes "in scope"
1500 and that secondary depth becomes the recorded scope depth. If the
1501 name is declared as a new variable, the old variable becomes "out of
1502 scope" and the recorded scope depth stays unchanged.
1504 - "out of scope". The variable is neither in scope nor conditionally
1505 in scope. It is permanently out of scope now and can be removed from
1506 the "in scope" stack. When a variable becomes out-of-scope it is
1507 moved to a separate list (`out_scope`) of variables which have fully
1508 known scope. This will be used at the end of each function to assign
1509 each variable a place in the stack frame.
1511 ###### variable fields
1512 int depth, min_depth;
1513 enum { OutScope, PendingScope, CondScope, InScope } scope;
1514 struct variable *in_scope;
1516 ###### parse context
1518 struct variable *in_scope;
1519 struct variable *out_scope;
1521 All variables with the same name are linked together using the
1522 'previous' link. Those variable that have been affirmatively merged all
1523 have a 'merged' pointer that points to one primary variable - the most
1524 recently declared instance. When merging variables, we need to also
1525 adjust the 'merged' pointer on any other variables that had previously
1526 been merged with the one that will no longer be primary.
1528 A variable that is no longer the most recent instance of a name may
1529 still have "pending" scope, if it might still be merged with most
1530 recent instance. These variables don't really belong in the
1531 "in_scope" list, but are not immediately removed when a new instance
1532 is found. Instead, they are detected and ignored when considering the
1533 list of in_scope names.
1535 The storage of the value of a variable will be described later. For now
1536 we just need to know that when a variable goes out of scope, it might
1537 need to be freed. For this we need to be able to find it, so assume that
1538 `var_value()` will provide that.
1540 ###### variable fields
1541 struct variable *merged;
1543 ###### ast functions
1545 static void variable_merge(struct variable *primary, struct variable *secondary)
1549 primary = primary->merged;
1551 for (v = primary->previous; v; v=v->previous)
1552 if (v == secondary || v == secondary->merged ||
1553 v->merged == secondary ||
1554 v->merged == secondary->merged) {
1555 v->scope = OutScope;
1556 v->merged = primary;
1557 if (v->scope_start < primary->scope_start)
1558 primary->scope_start = v->scope_start;
1559 if (v->scope_end > primary->scope_end)
1560 primary->scope_end = v->scope_end; // NOTEST
1561 variable_unlink_exec(v);
1565 ###### forward decls
1566 static struct value *var_value(struct parse_context *c, struct variable *v);
1568 ###### free global vars
1570 while (context.varlist) {
1571 struct binding *b = context.varlist;
1572 struct variable *v = b->var;
1573 context.varlist = b->next;
1576 struct variable *next = v->previous;
1579 free_value(v->type, var_value(&context, v));
1581 // This is a global constant
1582 free_exec(v->where_decl);
1589 #### Manipulating Bindings
1591 When a name is conditionally visible, a new declaration discards the old
1592 binding - the condition lapses. Similarly when we reach the end of a
1593 function (outermost non-global scope) any conditional scope must lapse.
1594 Conversely a usage of the name affirms the visibility and extends it to
1595 the end of the containing block - i.e. the block that contains both the
1596 original declaration and the latest usage. This is determined from
1597 `min_depth`. When a conditionally visible variable gets affirmed like
1598 this, it is also merged with other conditionally visible variables with
1601 When we parse a variable declaration we either report an error if the
1602 name is currently bound, or create a new variable at the current nest
1603 depth if the name is unbound or bound to a conditionally scoped or
1604 pending-scope variable. If the previous variable was conditionally
1605 scoped, it and its homonyms becomes out-of-scope.
1607 When we parse a variable reference (including non-declarative assignment
1608 "foo = bar") we report an error if the name is not bound or is bound to
1609 a pending-scope variable; update the scope if the name is bound to a
1610 conditionally scoped variable; or just proceed normally if the named
1611 variable is in scope.
1613 When we exit a scope, any variables bound at this level are either
1614 marked out of scope or pending-scoped, depending on whether the scope
1615 was sequential or parallel. Here a "parallel" scope means the "then"
1616 or "else" part of a conditional, or any "case" or "else" branch of a
1617 switch. Other scopes are "sequential".
1619 When exiting a parallel scope we check if there are any variables that
1620 were previously pending and are still visible. If there are, then
1621 they weren't redeclared in the most recent scope, so they cannot be
1622 merged and must become out-of-scope. If it is not the first of
1623 parallel scopes (based on `child_count`), we check that there was a
1624 previous binding that is still pending-scope. If there isn't, the new
1625 variable must now be out-of-scope.
1627 When exiting a sequential scope that immediately enclosed parallel
1628 scopes, we need to resolve any pending-scope variables. If there was
1629 no `else` clause, and we cannot determine that the `switch` was exhaustive,
1630 we need to mark all pending-scope variable as out-of-scope. Otherwise
1631 all pending-scope variables become conditionally scoped.
1634 enum closetype { CloseSequential, CloseFunction, CloseParallel, CloseElse };
1636 ###### ast functions
1638 static struct variable *var_decl(struct parse_context *c, struct text s)
1640 struct binding *b = find_binding(c, s);
1641 struct variable *v = b->var;
1643 switch (v ? v->scope : OutScope) {
1645 /* Caller will report the error */
1649 v && v->scope == CondScope;
1651 v->scope = OutScope;
1655 v = calloc(1, sizeof(*v));
1656 v->previous = b->var;
1660 v->min_depth = v->depth = c->scope_depth;
1662 v->in_scope = c->in_scope;
1663 v->scope_start = c->scope_count;
1669 static struct variable *var_ref(struct parse_context *c, struct text s)
1671 struct binding *b = find_binding(c, s);
1672 struct variable *v = b->var;
1673 struct variable *v2;
1675 switch (v ? v->scope : OutScope) {
1678 /* Caller will report the error */
1681 /* All CondScope variables of this name need to be merged
1682 * and become InScope
1684 v->depth = v->min_depth;
1686 for (v2 = v->previous;
1687 v2 && v2->scope == CondScope;
1689 variable_merge(v, v2);
1697 static int var_refile(struct parse_context *c, struct variable *v)
1699 /* Variable just went out of scope. Add it to the out_scope
1700 * list, sorted by ->scope_start
1702 struct variable **vp = &c->out_scope;
1703 while ((*vp) && (*vp)->scope_start < v->scope_start)
1704 vp = &(*vp)->in_scope;
1710 static void var_block_close(struct parse_context *c, enum closetype ct,
1713 /* Close off all variables that are in_scope.
1714 * Some variables in c->scope may already be not-in-scope,
1715 * such as when a PendingScope variable is hidden by a new
1716 * variable with the same name.
1717 * So we check for v->name->var != v and drop them.
1718 * If we choose to make a variable OutScope, we drop it
1721 struct variable *v, **vp, *v2;
1724 for (vp = &c->in_scope;
1725 (v = *vp) && v->min_depth > c->scope_depth;
1726 (v->scope == OutScope || v->name->var != v)
1727 ? (*vp = v->in_scope, var_refile(c, v))
1728 : ( vp = &v->in_scope, 0)) {
1729 v->min_depth = c->scope_depth;
1730 if (v->name->var != v)
1731 /* This is still in scope, but we haven't just
1735 v->min_depth = c->scope_depth;
1736 if (v->scope == InScope)
1737 v->scope_end = c->scope_count;
1738 if (v->scope == InScope && e && !v->global) {
1739 /* This variable gets cleaned up when 'e' finishes */
1740 variable_unlink_exec(v);
1741 v->cleanup_exec = e;
1742 v->next_free = e->to_free;
1747 case CloseParallel: /* handle PendingScope */
1751 if (c->scope_stack->child_count == 1)
1752 /* first among parallel branches */
1753 v->scope = PendingScope;
1754 else if (v->previous &&
1755 v->previous->scope == PendingScope)
1756 /* all previous branches used name */
1757 v->scope = PendingScope;
1758 else if (v->type == Tlabel)
1759 /* Labels remain pending even when not used */
1760 v->scope = PendingScope; // UNTESTED
1762 v->scope = OutScope;
1763 if (ct == CloseElse) {
1764 /* All Pending variables with this name
1765 * are now Conditional */
1767 v2 && v2->scope == PendingScope;
1769 v2->scope = CondScope;
1773 /* Not possible as it would require
1774 * parallel scope to be nested immediately
1775 * in a parallel scope, and that never
1779 /* Not possible as we already tested for
1786 if (v->scope == CondScope)
1787 /* Condition cannot continue past end of function */
1790 case CloseSequential:
1791 if (v->type == Tlabel)
1792 v->scope = PendingScope;
1795 v->scope = OutScope;
1798 /* There was no 'else', so we can only become
1799 * conditional if we know the cases were exhaustive,
1800 * and that doesn't mean anything yet.
1801 * So only labels become conditional..
1804 v2 && v2->scope == PendingScope;
1806 if (v2->type == Tlabel)
1807 v2->scope = CondScope;
1809 v2->scope = OutScope;
1812 case OutScope: break;
1821 The value of a variable is store separately from the variable, on an
1822 analogue of a stack frame. There are (currently) two frames that can be
1823 active. A global frame which currently only stores constants, and a
1824 stacked frame which stores local variables. Each variable knows if it
1825 is global or not, and what its index into the frame is.
1827 Values in the global frame are known immediately they are relevant, so
1828 the frame needs to be reallocated as it grows so it can store those
1829 values. The local frame doesn't get values until the interpreted phase
1830 is started, so there is no need to allocate until the size is known.
1832 We initialize the `frame_pos` to an impossible value, so that we can
1833 tell if it was set or not later.
1835 ###### variable fields
1839 ###### variable init
1842 ###### parse context
1844 short global_size, global_alloc;
1846 void *global, *local;
1848 ###### ast functions
1850 static struct value *var_value(struct parse_context *c, struct variable *v)
1853 if (!c->local || !v->type)
1854 return NULL; // NOTEST
1855 if (v->frame_pos + v->type->size > c->local_size) {
1856 printf("INVALID frame_pos\n"); // NOTEST
1859 return c->local + v->frame_pos;
1861 if (c->global_size > c->global_alloc) {
1862 int old = c->global_alloc;
1863 c->global_alloc = (c->global_size | 1023) + 1024;
1864 c->global = realloc(c->global, c->global_alloc);
1865 memset(c->global + old, 0, c->global_alloc - old);
1867 return c->global + v->frame_pos;
1870 static struct value *global_alloc(struct parse_context *c, struct type *t,
1871 struct variable *v, struct value *init)
1874 struct variable scratch;
1876 if (t->prepare_type)
1877 t->prepare_type(c, t, 1); // NOTEST
1879 if (c->global_size & (t->align - 1))
1880 c->global_size = (c->global_size + t->align) & ~(t->align-1);
1885 v->frame_pos = c->global_size;
1887 c->global_size += v->type->size;
1888 ret = var_value(c, v);
1890 memcpy(ret, init, t->size);
1896 As global values are found -- struct field initializers, labels etc --
1897 `global_alloc()` is called to record the value in the global frame.
1899 When the program is fully parsed, each function is analysed, we need to
1900 walk the list of variables local to that function and assign them an
1901 offset in the stack frame. For this we have `scope_finalize()`.
1903 We keep the stack from dense by re-using space for between variables
1904 that are not in scope at the same time. The `out_scope` list is sorted
1905 by `scope_start` and as we process a varible, we move it to an FIFO
1906 stack. For each variable we consider, we first discard any from the
1907 stack anything that went out of scope before the new variable came in.
1908 Then we place the new variable just after the one at the top of the
1911 ###### ast functions
1913 static void scope_finalize(struct parse_context *c, struct type *ft)
1915 int size = ft->function.local_size;
1916 struct variable *next = ft->function.scope;
1917 struct variable *done = NULL;
1920 struct variable *v = next;
1921 struct type *t = v->type;
1928 if (v->frame_pos >= 0)
1930 while (done && done->scope_end < v->scope_start)
1931 done = done->in_scope;
1933 pos = done->frame_pos + done->type->size;
1935 pos = ft->function.local_size;
1936 if (pos & (t->align - 1))
1937 pos = (pos + t->align) & ~(t->align-1);
1939 if (size < pos + v->type->size)
1940 size = pos + v->type->size;
1944 c->out_scope = NULL;
1945 ft->function.local_size = size;
1948 ###### free context storage
1949 free(context.global);
1951 #### Variables as executables
1953 Just as we used a `val` to wrap a value into an `exec`, we similarly
1954 need a `var` to wrap a `variable` into an exec. While each `val`
1955 contained a copy of the value, each `var` holds a link to the variable
1956 because it really is the same variable no matter where it appears.
1957 When a variable is used, we need to remember to follow the `->merged`
1958 link to find the primary instance.
1960 When a variable is declared, it may or may not be given an explicit
1961 type. We need to record which so that we can report the parsed code
1970 struct variable *var;
1973 ###### variable fields
1981 VariableDecl -> IDENTIFIER : ${ {
1982 struct variable *v = var_decl(c, $1.txt);
1983 $0 = new_pos(var, $1);
1988 v = var_ref(c, $1.txt);
1990 type_err(c, "error: variable '%v' redeclared",
1992 type_err(c, "info: this is where '%v' was first declared",
1993 v->where_decl, NULL, 0, NULL);
1996 | IDENTIFIER :: ${ {
1997 struct variable *v = var_decl(c, $1.txt);
1998 $0 = new_pos(var, $1);
2004 v = var_ref(c, $1.txt);
2006 type_err(c, "error: variable '%v' redeclared",
2008 type_err(c, "info: this is where '%v' was first declared",
2009 v->where_decl, NULL, 0, NULL);
2012 | IDENTIFIER : Type ${ {
2013 struct variable *v = var_decl(c, $1.txt);
2014 $0 = new_pos(var, $1);
2020 v->explicit_type = 1;
2022 v = var_ref(c, $1.txt);
2024 type_err(c, "error: variable '%v' redeclared",
2026 type_err(c, "info: this is where '%v' was first declared",
2027 v->where_decl, NULL, 0, NULL);
2030 | IDENTIFIER :: Type ${ {
2031 struct variable *v = var_decl(c, $1.txt);
2032 $0 = new_pos(var, $1);
2039 v->explicit_type = 1;
2041 v = var_ref(c, $1.txt);
2043 type_err(c, "error: variable '%v' redeclared",
2045 type_err(c, "info: this is where '%v' was first declared",
2046 v->where_decl, NULL, 0, NULL);
2051 Variable -> IDENTIFIER ${ {
2052 struct variable *v = var_ref(c, $1.txt);
2053 $0 = new_pos(var, $1);
2055 /* This might be a label - allocate a var just in case */
2056 v = var_decl(c, $1.txt);
2063 cast(var, $0)->var = v;
2066 ###### print exec cases
2069 struct var *v = cast(var, e);
2071 struct binding *b = v->var->name;
2072 printf("%.*s", b->name.len, b->name.txt);
2079 if (loc && loc->type == Xvar) {
2080 struct var *v = cast(var, loc);
2082 struct binding *b = v->var->name;
2083 fprintf(stderr, "%.*s", b->name.len, b->name.txt);
2085 fputs("???", stderr); // NOTEST
2087 fputs("NOTVAR", stderr);
2090 ###### propagate exec cases
2094 struct var *var = cast(var, prog);
2095 struct variable *v = var->var;
2097 type_err(c, "%d:BUG: no variable!!", prog, NULL, 0, NULL); // NOTEST
2098 return Tnone; // NOTEST
2101 if (v->constant && (rules & Rnoconstant)) {
2102 type_err(c, "error: Cannot assign to a constant: %v",
2103 prog, NULL, 0, NULL);
2104 type_err(c, "info: name was defined as a constant here",
2105 v->where_decl, NULL, 0, NULL);
2108 if (v->type == Tnone && v->where_decl == prog)
2109 type_err(c, "error: variable used but not declared: %v",
2110 prog, NULL, 0, NULL);
2111 if (v->type == NULL) {
2112 if (type && *ok != 0) {
2114 v->where_set = prog;
2119 if (!type_compat(type, v->type, rules)) {
2120 type_err(c, "error: expected %1%r but variable '%v' is %2", prog,
2121 type, rules, v->type);
2122 type_err(c, "info: this is where '%v' was set to %1", v->where_set,
2123 v->type, rules, NULL);
2130 ###### interp exec cases
2133 struct var *var = cast(var, e);
2134 struct variable *v = var->var;
2137 lrv = var_value(c, v);
2142 ###### ast functions
2144 static void free_var(struct var *v)
2149 ###### free exec cases
2150 case Xvar: free_var(cast(var, e)); break;
2155 Now that we have the shape of the interpreter in place we can add some
2156 complex types and connected them in to the data structures and the
2157 different phases of parse, analyse, print, interpret.
2159 Being "complex" the language will naturally have syntax to access
2160 specifics of objects of these types. These will fit into the grammar as
2161 "Terms" which are the things that are combined with various operators to
2162 form "Expression". Where a Term is formed by some operation on another
2163 Term, the subordinate Term will always come first, so for example a
2164 member of an array will be expressed as the Term for the array followed
2165 by an index in square brackets. The strict rule of using postfix
2166 operations makes precedence irrelevant within terms. To provide a place
2167 to put the grammar for each terms of each type, we will start out by
2168 introducing the "Term" grammar production, with contains at least a
2169 simple "Value" (to be explained later).
2173 Term -> Value ${ $0 = $<1; }$
2174 | Variable ${ $0 = $<1; }$
2177 Thus far the complex types we have are arrays and structs.
2181 Arrays can be declared by giving a size and a type, as `[size]type' so
2182 `freq:[26]number` declares `freq` to be an array of 26 numbers. The
2183 size can be either a literal number, or a named constant. Some day an
2184 arbitrary expression will be supported.
2186 As a formal parameter to a function, the array can be declared with a
2187 new variable as the size: `name:[size::number]string`. The `size`
2188 variable is set to the size of the array and must be a constant. As
2189 `number` is the only supported type, it can be left out:
2190 `name:[size::]string`.
2192 Arrays cannot be assigned. When pointers are introduced we will also
2193 introduce array slices which can refer to part or all of an array -
2194 the assignment syntax will create a slice. For now, an array can only
2195 ever be referenced by the name it is declared with. It is likely that
2196 a "`copy`" primitive will eventually be define which can be used to
2197 make a copy of an array with controllable recursive depth.
2199 For now we have two sorts of array, those with fixed size either because
2200 it is given as a literal number or because it is a struct member (which
2201 cannot have a runtime-changing size), and those with a size that is
2202 determined at runtime - local variables with a const size. The former
2203 have their size calculated at parse time, the latter at run time.
2205 For the latter type, the `size` field of the type is the size of a
2206 pointer, and the array is reallocated every time it comes into scope.
2208 We differentiate struct fields with a const size from local variables
2209 with a const size by whether they are prepared at parse time or not.
2211 ###### type union fields
2214 int unspec; // size is unspecified - vsize must be set.
2217 struct variable *vsize;
2218 struct type *member;
2221 ###### value union fields
2222 void *array; // used if not static_size
2224 ###### value functions
2226 static void array_prepare_type(struct parse_context *c, struct type *type,
2229 struct value *vsize;
2231 if (type->array.static_size)
2233 if (type->array.unspec && parse_time)
2236 if (type->array.vsize) {
2237 vsize = var_value(c, type->array.vsize);
2241 mpz_tdiv_q(q, mpq_numref(vsize->num), mpq_denref(vsize->num));
2242 type->array.size = mpz_get_si(q);
2246 if (parse_time && type->array.member->size) {
2247 type->array.static_size = 1;
2248 type->size = type->array.size * type->array.member->size;
2249 type->align = type->array.member->align;
2253 static void array_init(struct type *type, struct value *val)
2256 void *ptr = val->ptr;
2260 if (!type->array.static_size) {
2261 val->array = calloc(type->array.size,
2262 type->array.member->size);
2265 for (i = 0; i < type->array.size; i++) {
2267 v = (void*)ptr + i * type->array.member->size;
2268 val_init(type->array.member, v);
2272 static void array_free(struct type *type, struct value *val)
2275 void *ptr = val->ptr;
2277 if (!type->array.static_size)
2279 for (i = 0; i < type->array.size; i++) {
2281 v = (void*)ptr + i * type->array.member->size;
2282 free_value(type->array.member, v);
2284 if (!type->array.static_size)
2288 static int array_compat(struct type *require, struct type *have)
2290 if (have->compat != require->compat)
2292 /* Both are arrays, so we can look at details */
2293 if (!type_compat(require->array.member, have->array.member, 0))
2295 if (have->array.unspec && require->array.unspec) {
2296 if (have->array.vsize && require->array.vsize &&
2297 have->array.vsize != require->array.vsize) // UNTESTED
2298 /* sizes might not be the same */
2299 return 0; // UNTESTED
2302 if (have->array.unspec || require->array.unspec)
2303 return 1; // UNTESTED
2304 if (require->array.vsize == NULL && have->array.vsize == NULL)
2305 return require->array.size == have->array.size;
2307 return require->array.vsize == have->array.vsize; // UNTESTED
2310 static void array_print_type(struct type *type, FILE *f)
2313 if (type->array.vsize) {
2314 struct binding *b = type->array.vsize->name;
2315 fprintf(f, "%.*s%s]", b->name.len, b->name.txt,
2316 type->array.unspec ? "::" : "");
2317 } else if (type->array.size)
2318 fprintf(f, "%d]", type->array.size);
2321 type_print(type->array.member, f);
2324 static struct type array_prototype = {
2326 .prepare_type = array_prepare_type,
2327 .print_type = array_print_type,
2328 .compat = array_compat,
2330 .size = sizeof(void*),
2331 .align = sizeof(void*),
2334 ###### declare terminals
2339 | [ NUMBER ] Type ${ {
2345 if (number_parse(num, tail, $2.txt) == 0)
2346 tok_err(c, "error: unrecognised number", &$2);
2348 tok_err(c, "error: unsupported number suffix", &$2);
2351 elements = mpz_get_ui(mpq_numref(num));
2352 if (mpz_cmp_ui(mpq_denref(num), 1) != 0) {
2353 tok_err(c, "error: array size must be an integer",
2355 } else if (mpz_cmp_ui(mpq_numref(num), 1UL << 30) >= 0)
2356 tok_err(c, "error: array size is too large",
2361 $0 = t = add_anon_type(c, &array_prototype, "array[%d]", elements );
2362 t->array.size = elements;
2363 t->array.member = $<4;
2364 t->array.vsize = NULL;
2367 | [ IDENTIFIER ] Type ${ {
2368 struct variable *v = var_ref(c, $2.txt);
2371 tok_err(c, "error: name undeclared", &$2);
2372 else if (!v->constant)
2373 tok_err(c, "error: array size must be a constant", &$2);
2375 $0 = add_anon_type(c, &array_prototype, "array[%.*s]", $2.txt.len, $2.txt.txt);
2376 $0->array.member = $<4;
2378 $0->array.vsize = v;
2383 OptType -> Type ${ $0 = $<1; }$
2386 ###### formal type grammar
2388 | [ IDENTIFIER :: OptType ] Type ${ {
2389 struct variable *v = var_decl(c, $ID.txt);
2395 $0 = add_anon_type(c, &array_prototype, "array[var]");
2396 $0->array.member = $<6;
2398 $0->array.unspec = 1;
2399 $0->array.vsize = v;
2407 | Term [ Expression ] ${ {
2408 struct binode *b = new(binode);
2415 ###### print binode cases
2417 print_exec(b->left, -1, bracket);
2419 print_exec(b->right, -1, bracket);
2423 ###### propagate binode cases
2425 /* left must be an array, right must be a number,
2426 * result is the member type of the array
2428 propagate_types(b->right, c, ok, Tnum, 0);
2429 t = propagate_types(b->left, c, ok, NULL, rules & Rnoconstant);
2430 if (!t || t->compat != array_compat) {
2431 type_err(c, "error: %1 cannot be indexed", prog, t, 0, NULL);
2434 if (!type_compat(type, t->array.member, rules)) {
2435 type_err(c, "error: have %1 but need %2", prog,
2436 t->array.member, rules, type);
2438 return t->array.member;
2442 ###### interp binode cases
2448 lleft = linterp_exec(c, b->left, <ype);
2449 right = interp_exec(c, b->right, &rtype);
2451 mpz_tdiv_q(q, mpq_numref(right.num), mpq_denref(right.num));
2455 if (ltype->array.static_size)
2458 ptr = *(void**)lleft;
2459 rvtype = ltype->array.member;
2460 if (i >= 0 && i < ltype->array.size)
2461 lrv = ptr + i * rvtype->size;
2463 val_init(ltype->array.member, &rv); // UNSAFE
2470 A `struct` is a data-type that contains one or more other data-types.
2471 It differs from an array in that each member can be of a different
2472 type, and they are accessed by name rather than by number. Thus you
2473 cannot choose an element by calculation, you need to know what you
2476 The language makes no promises about how a given structure will be
2477 stored in memory - it is free to rearrange fields to suit whatever
2478 criteria seems important.
2480 Structs are declared separately from program code - they cannot be
2481 declared in-line in a variable declaration like arrays can. A struct
2482 is given a name and this name is used to identify the type - the name
2483 is not prefixed by the word `struct` as it would be in C.
2485 Structs are only treated as the same if they have the same name.
2486 Simply having the same fields in the same order is not enough. This
2487 might change once we can create structure initializers from a list of
2490 Each component datum is identified much like a variable is declared,
2491 with a name, one or two colons, and a type. The type cannot be omitted
2492 as there is no opportunity to deduce the type from usage. An initial
2493 value can be given following an equals sign, so
2495 ##### Example: a struct type
2501 would declare a type called "complex" which has two number fields,
2502 each initialised to zero.
2504 Struct will need to be declared separately from the code that uses
2505 them, so we will need to be able to print out the declaration of a
2506 struct when reprinting the whole program. So a `print_type_decl` type
2507 function will be needed.
2509 ###### type union fields
2521 ###### type functions
2522 void (*print_type_decl)(struct type *type, FILE *f);
2524 ###### value functions
2526 static void structure_init(struct type *type, struct value *val)
2530 for (i = 0; i < type->structure.nfields; i++) {
2532 v = (void*) val->ptr + type->structure.fields[i].offset;
2533 if (type->structure.fields[i].init)
2534 dup_value(type->structure.fields[i].type,
2535 type->structure.fields[i].init,
2538 val_init(type->structure.fields[i].type, v);
2542 static void structure_free(struct type *type, struct value *val)
2546 for (i = 0; i < type->structure.nfields; i++) {
2548 v = (void*)val->ptr + type->structure.fields[i].offset;
2549 free_value(type->structure.fields[i].type, v);
2553 static void structure_free_type(struct type *t)
2556 for (i = 0; i < t->structure.nfields; i++)
2557 if (t->structure.fields[i].init) {
2558 free_value(t->structure.fields[i].type,
2559 t->structure.fields[i].init);
2561 free(t->structure.fields);
2564 static struct type structure_prototype = {
2565 .init = structure_init,
2566 .free = structure_free,
2567 .free_type = structure_free_type,
2568 .print_type_decl = structure_print_type,
2582 ###### free exec cases
2584 free_exec(cast(fieldref, e)->left);
2588 ###### declare terminals
2593 | Term . IDENTIFIER ${ {
2594 struct fieldref *fr = new_pos(fieldref, $2);
2601 ###### print exec cases
2605 struct fieldref *f = cast(fieldref, e);
2606 print_exec(f->left, -1, bracket);
2607 printf(".%.*s", f->name.len, f->name.txt);
2611 ###### ast functions
2612 static int find_struct_index(struct type *type, struct text field)
2615 for (i = 0; i < type->structure.nfields; i++)
2616 if (text_cmp(type->structure.fields[i].name, field) == 0)
2621 ###### propagate exec cases
2625 struct fieldref *f = cast(fieldref, prog);
2626 struct type *st = propagate_types(f->left, c, ok, NULL, 0);
2629 type_err(c, "error: unknown type for field access", f->left, // UNTESTED
2631 else if (st->init != structure_init)
2632 type_err(c, "error: field reference attempted on %1, not a struct",
2633 f->left, st, 0, NULL);
2634 else if (f->index == -2) {
2635 f->index = find_struct_index(st, f->name);
2637 type_err(c, "error: cannot find requested field in %1",
2638 f->left, st, 0, NULL);
2640 if (f->index >= 0) {
2641 struct type *ft = st->structure.fields[f->index].type;
2642 if (!type_compat(type, ft, rules))
2643 type_err(c, "error: have %1 but need %2", prog,
2650 ###### interp exec cases
2653 struct fieldref *f = cast(fieldref, e);
2655 struct value *lleft = linterp_exec(c, f->left, <ype);
2656 lrv = (void*)lleft->ptr + ltype->structure.fields[f->index].offset;
2657 rvtype = ltype->structure.fields[f->index].type;
2663 struct fieldlist *prev;
2667 ###### ast functions
2668 static void free_fieldlist(struct fieldlist *f)
2672 free_fieldlist(f->prev);
2674 free_value(f->f.type, f->f.init); // UNTESTED
2675 free(f->f.init); // UNTESTED
2680 ###### top level grammar
2681 DeclareStruct -> struct IDENTIFIER FieldBlock Newlines ${ {
2683 add_type(c, $2.txt, &structure_prototype);
2685 struct fieldlist *f;
2687 for (f = $3; f; f=f->prev)
2690 t->structure.nfields = cnt;
2691 t->structure.fields = calloc(cnt, sizeof(struct field));
2694 int a = f->f.type->align;
2696 t->structure.fields[cnt] = f->f;
2697 if (t->size & (a-1))
2698 t->size = (t->size | (a-1)) + 1;
2699 t->structure.fields[cnt].offset = t->size;
2700 t->size += ((f->f.type->size - 1) | (a-1)) + 1;
2709 FieldBlock -> { IN OptNL FieldLines OUT OptNL } ${ $0 = $<FL; }$
2710 | { SimpleFieldList } ${ $0 = $<SFL; }$
2711 | IN OptNL FieldLines OUT ${ $0 = $<FL; }$
2712 | SimpleFieldList EOL ${ $0 = $<SFL; }$
2714 FieldLines -> SimpleFieldList Newlines ${ $0 = $<SFL; }$
2715 | FieldLines SimpleFieldList Newlines ${
2720 SimpleFieldList -> Field ${ $0 = $<F; }$
2721 | SimpleFieldList ; Field ${
2725 | SimpleFieldList ; ${
2728 | ERROR ${ tok_err(c, "Syntax error in struct field", &$1); }$
2730 Field -> IDENTIFIER : Type = Expression ${ {
2733 $0 = calloc(1, sizeof(struct fieldlist));
2734 $0->f.name = $1.txt;
2739 propagate_types($<5, c, &ok, $3, 0);
2742 c->parse_error = 1; // UNTESTED
2744 struct value vl = interp_exec(c, $5, NULL);
2745 $0->f.init = global_alloc(c, $0->f.type, NULL, &vl);
2748 | IDENTIFIER : Type ${
2749 $0 = calloc(1, sizeof(struct fieldlist));
2750 $0->f.name = $1.txt;
2752 if ($0->f.type->prepare_type)
2753 $0->f.type->prepare_type(c, $0->f.type, 1);
2756 ###### forward decls
2757 static void structure_print_type(struct type *t, FILE *f);
2759 ###### value functions
2760 static void structure_print_type(struct type *t, FILE *f)
2764 fprintf(f, "struct %.*s\n", t->name.len, t->name.txt);
2766 for (i = 0; i < t->structure.nfields; i++) {
2767 struct field *fl = t->structure.fields + i;
2768 fprintf(f, " %.*s : ", fl->name.len, fl->name.txt);
2769 type_print(fl->type, f);
2770 if (fl->type->print && fl->init) {
2772 if (fl->type == Tstr)
2773 fprintf(f, "\""); // UNTESTED
2774 print_value(fl->type, fl->init, f);
2775 if (fl->type == Tstr)
2776 fprintf(f, "\""); // UNTESTED
2782 ###### print type decls
2787 while (target != 0) {
2789 for (t = context.typelist; t ; t=t->next)
2790 if (!t->anon && t->print_type_decl &&
2800 t->print_type_decl(t, stdout);
2808 A function is a chunk of code which can be passed parameters and can
2809 return results. Each function has a type which includes the set of
2810 parameters and the return value. As yet these types cannot be declared
2811 separately from the function itself.
2813 The parameters can be specified either in parentheses as a ';' separated
2816 ##### Example: function 1
2818 func main(av:[ac::number]string; env:[envc::number]string)
2821 or as an indented list of one parameter per line (though each line can
2822 be a ';' separated list)
2824 ##### Example: function 2
2827 argv:[argc::number]string
2828 env:[envc::number]string
2832 In the first case a return type can follow the parentheses after a colon,
2833 in the second it is given on a line starting with the word `return`.
2835 ##### Example: functions that return
2837 func add(a:number; b:number): number
2847 Rather than returning a type, the function can specify a set of local
2848 variables to return as a struct. The values of these variables when the
2849 function exits will be provided to the caller. For this the return type
2850 is replaced with a block of result declarations, either in parentheses
2851 or bracketed by `return` and `do`.
2853 ##### Example: functions returning multiple variables
2855 func to_cartesian(rho:number; theta:number):(x:number; y:number)
2868 For constructing the lists we use a `List` binode, which will be
2869 further detailed when Expression Lists are introduced.
2871 ###### type union fields
2874 struct binode *params;
2875 struct type *return_type;
2876 struct variable *scope;
2877 int inline_result; // return value is at start of 'local'
2881 ###### value union fields
2882 struct exec *function;
2884 ###### type functions
2885 void (*check_args)(struct parse_context *c, int *ok,
2886 struct type *require, struct exec *args);
2888 ###### value functions
2890 static void function_free(struct type *type, struct value *val)
2892 free_exec(val->function);
2893 val->function = NULL;
2896 static int function_compat(struct type *require, struct type *have)
2898 // FIXME can I do anything here yet?
2902 static void function_check_args(struct parse_context *c, int *ok,
2903 struct type *require, struct exec *args)
2905 /* This should be 'compat', but we don't have a 'tuple' type to
2906 * hold the type of 'args'
2908 struct binode *arg = cast(binode, args);
2909 struct binode *param = require->function.params;
2912 struct var *pv = cast(var, param->left);
2914 type_err(c, "error: insufficient arguments to function.",
2915 args, NULL, 0, NULL);
2919 propagate_types(arg->left, c, ok, pv->var->type, 0);
2920 param = cast(binode, param->right);
2921 arg = cast(binode, arg->right);
2924 type_err(c, "error: too many arguments to function.",
2925 args, NULL, 0, NULL);
2928 static void function_print(struct type *type, struct value *val, FILE *f)
2930 print_exec(val->function, 1, 0);
2933 static void function_print_type_decl(struct type *type, FILE *f)
2937 for (b = type->function.params; b; b = cast(binode, b->right)) {
2938 struct variable *v = cast(var, b->left)->var;
2939 fprintf(f, "%.*s%s", v->name->name.len, v->name->name.txt,
2940 v->constant ? "::" : ":");
2941 type_print(v->type, f);
2946 if (type->function.return_type != Tnone) {
2948 if (type->function.inline_result) {
2950 struct type *t = type->function.return_type;
2952 for (i = 0; i < t->structure.nfields; i++) {
2953 struct field *fl = t->structure.fields + i;
2956 fprintf(f, "%.*s:", fl->name.len, fl->name.txt);
2957 type_print(fl->type, f);
2961 type_print(type->function.return_type, f);
2966 static void function_free_type(struct type *t)
2968 free_exec(t->function.params);
2971 static struct type function_prototype = {
2972 .size = sizeof(void*),
2973 .align = sizeof(void*),
2974 .free = function_free,
2975 .compat = function_compat,
2976 .check_args = function_check_args,
2977 .print = function_print,
2978 .print_type_decl = function_print_type_decl,
2979 .free_type = function_free_type,
2982 ###### declare terminals
2992 FuncName -> IDENTIFIER ${ {
2993 struct variable *v = var_decl(c, $1.txt);
2994 struct var *e = new_pos(var, $1);
3000 v = var_ref(c, $1.txt);
3002 type_err(c, "error: function '%v' redeclared",
3004 type_err(c, "info: this is where '%v' was first declared",
3005 v->where_decl, NULL, 0, NULL);
3011 Args -> ArgsLine NEWLINE ${ $0 = $<AL; }$
3012 | Args ArgsLine NEWLINE ${ {
3013 struct binode *b = $<AL;
3014 struct binode **bp = &b;
3016 bp = (struct binode **)&(*bp)->left;
3021 ArgsLine -> ${ $0 = NULL; }$
3022 | Varlist ${ $0 = $<1; }$
3023 | Varlist ; ${ $0 = $<1; }$
3025 Varlist -> Varlist ; ArgDecl ${
3039 ArgDecl -> IDENTIFIER : FormalType ${ {
3040 struct variable *v = var_decl(c, $1.txt);
3046 ##### Function calls
3048 A function call can appear either as an expression or as a statement.
3049 We use a new 'Funcall' binode type to link the function with a list of
3050 arguments, form with the 'List' nodes.
3052 We have already seen the "Term" which is how a function call can appear
3053 in an expression. To parse a function call into a statement we include
3054 it in the "SimpleStatement Grammar" which will be described later.
3060 | Term ( ExpressionList ) ${ {
3061 struct binode *b = new(binode);
3064 b->right = reorder_bilist($<EL);
3068 struct binode *b = new(binode);
3075 ###### SimpleStatement Grammar
3077 | Term ( ExpressionList ) ${ {
3078 struct binode *b = new(binode);
3081 b->right = reorder_bilist($<EL);
3085 ###### print binode cases
3088 do_indent(indent, "");
3089 print_exec(b->left, -1, bracket);
3091 for (b = cast(binode, b->right); b; b = cast(binode, b->right)) {
3094 print_exec(b->left, -1, bracket);
3104 ###### propagate binode cases
3107 /* Every arg must match formal parameter, and result
3108 * is return type of function
3110 struct binode *args = cast(binode, b->right);
3111 struct var *v = cast(var, b->left);
3113 if (!v->var->type || v->var->type->check_args == NULL) {
3114 type_err(c, "error: attempt to call a non-function.",
3115 prog, NULL, 0, NULL);
3118 v->var->type->check_args(c, ok, v->var->type, args);
3119 return v->var->type->function.return_type;
3122 ###### interp binode cases
3125 struct var *v = cast(var, b->left);
3126 struct type *t = v->var->type;
3127 void *oldlocal = c->local;
3128 int old_size = c->local_size;
3129 void *local = calloc(1, t->function.local_size);
3130 struct value *fbody = var_value(c, v->var);
3131 struct binode *arg = cast(binode, b->right);
3132 struct binode *param = t->function.params;
3135 struct var *pv = cast(var, param->left);
3136 struct type *vtype = NULL;
3137 struct value val = interp_exec(c, arg->left, &vtype);
3139 c->local = local; c->local_size = t->function.local_size;
3140 lval = var_value(c, pv->var);
3141 c->local = oldlocal; c->local_size = old_size;
3142 memcpy(lval, &val, vtype->size);
3143 param = cast(binode, param->right);
3144 arg = cast(binode, arg->right);
3146 c->local = local; c->local_size = t->function.local_size;
3147 if (t->function.inline_result && dtype) {
3148 _interp_exec(c, fbody->function, NULL, NULL);
3149 memcpy(dest, local, dtype->size);
3150 rvtype = ret.type = NULL;
3152 rv = interp_exec(c, fbody->function, &rvtype);
3153 c->local = oldlocal; c->local_size = old_size;
3158 ## Complex executables: statements and expressions
3160 Now that we have types and values and variables and most of the basic
3161 Terms which provide access to these, we can explore the more complex
3162 code that combine all of these to get useful work done. Specifically
3163 statements and expressions.
3165 Expressions are various combinations of Terms. We will use operator
3166 precedence to ensure correct parsing. The simplest Expression is just a
3167 Term - others will follow.
3172 Expression -> Term ${ $0 = $<Term; }$
3173 ## expression grammar
3175 ### Expressions: Conditional
3177 Our first user of the `binode` will be conditional expressions, which
3178 is a bit odd as they actually have three components. That will be
3179 handled by having 2 binodes for each expression. The conditional
3180 expression is the lowest precedence operator which is why we define it
3181 first - to start the precedence list.
3183 Conditional expressions are of the form "value `if` condition `else`
3184 other_value". They associate to the right, so everything to the right
3185 of `else` is part of an else value, while only a higher-precedence to
3186 the left of `if` is the if values. Between `if` and `else` there is no
3187 room for ambiguity, so a full conditional expression is allowed in
3193 ###### declare terminals
3197 ###### expression grammar
3199 | Expression if Expression else Expression $$ifelse ${ {
3200 struct binode *b1 = new(binode);
3201 struct binode *b2 = new(binode);
3211 ###### print binode cases
3214 b2 = cast(binode, b->right);
3215 if (bracket) printf("(");
3216 print_exec(b2->left, -1, bracket);
3218 print_exec(b->left, -1, bracket);
3220 print_exec(b2->right, -1, bracket);
3221 if (bracket) printf(")");
3224 ###### propagate binode cases
3227 /* cond must be Tbool, others must match */
3228 struct binode *b2 = cast(binode, b->right);
3231 propagate_types(b->left, c, ok, Tbool, 0);
3232 t = propagate_types(b2->left, c, ok, type, Rnolabel);
3233 t2 = propagate_types(b2->right, c, ok, type ?: t, Rnolabel);
3237 ###### interp binode cases
3240 struct binode *b2 = cast(binode, b->right);
3241 left = interp_exec(c, b->left, <ype);
3243 rv = interp_exec(c, b2->left, &rvtype); // UNTESTED
3245 rv = interp_exec(c, b2->right, &rvtype);
3251 We take a brief detour, now that we have expressions, to describe lists
3252 of expressions. These will be needed for function parameters and
3253 possibly other situations. They seem generic enough to introduce here
3254 to be used elsewhere.
3256 And ExpressionList will use the `List` type of `binode`, building up at
3257 the end. And place where they are used will probably call
3258 `reorder_bilist()` to get a more normal first/next arrangement.
3260 ###### declare terminals
3263 `List` execs have no implicit semantics, so they are never propagated or
3264 interpreted. The can be printed as a comma separate list, which is how
3265 they are parsed. Note they are also used for function formal parameter
3266 lists. In that case a separate function is used to print them.
3268 ###### print binode cases
3272 print_exec(b->left, -1, bracket);
3275 b = cast(binode, b->right);
3279 ###### propagate binode cases
3280 case List: abort(); // NOTEST
3281 ###### interp binode cases
3282 case List: abort(); // NOTEST
3287 ExpressionList -> ExpressionList , Expression ${
3300 ### Expressions: Boolean
3302 The next class of expressions to use the `binode` will be Boolean
3303 expressions. "`and then`" and "`or else`" are similar to `and` and `or`
3304 have same corresponding precendence. The difference is that they don't
3305 evaluate the second expression if not necessary.
3314 ###### declare terminals
3319 ###### expression grammar
3320 | Expression or Expression ${ {
3321 struct binode *b = new(binode);
3327 | Expression or else Expression ${ {
3328 struct binode *b = new(binode);
3335 | Expression and Expression ${ {
3336 struct binode *b = new(binode);
3342 | Expression and then Expression ${ {
3343 struct binode *b = new(binode);
3350 | not Expression ${ {
3351 struct binode *b = new(binode);
3357 ###### print binode cases
3359 if (bracket) printf("(");
3360 print_exec(b->left, -1, bracket);
3362 print_exec(b->right, -1, bracket);
3363 if (bracket) printf(")");
3366 if (bracket) printf("(");
3367 print_exec(b->left, -1, bracket);
3368 printf(" and then ");
3369 print_exec(b->right, -1, bracket);
3370 if (bracket) printf(")");
3373 if (bracket) printf("(");
3374 print_exec(b->left, -1, bracket);
3376 print_exec(b->right, -1, bracket);
3377 if (bracket) printf(")");
3380 if (bracket) printf("(");
3381 print_exec(b->left, -1, bracket);
3382 printf(" or else ");
3383 print_exec(b->right, -1, bracket);
3384 if (bracket) printf(")");
3387 if (bracket) printf("(");
3389 print_exec(b->right, -1, bracket);
3390 if (bracket) printf(")");
3393 ###### propagate binode cases
3399 /* both must be Tbool, result is Tbool */
3400 propagate_types(b->left, c, ok, Tbool, 0);
3401 propagate_types(b->right, c, ok, Tbool, 0);
3402 if (type && type != Tbool)
3403 type_err(c, "error: %1 operation found where %2 expected", prog,
3407 ###### interp binode cases
3409 rv = interp_exec(c, b->left, &rvtype);
3410 right = interp_exec(c, b->right, &rtype);
3411 rv.bool = rv.bool && right.bool;
3414 rv = interp_exec(c, b->left, &rvtype);
3416 rv = interp_exec(c, b->right, NULL);
3419 rv = interp_exec(c, b->left, &rvtype);
3420 right = interp_exec(c, b->right, &rtype);
3421 rv.bool = rv.bool || right.bool;
3424 rv = interp_exec(c, b->left, &rvtype);
3426 rv = interp_exec(c, b->right, NULL);
3429 rv = interp_exec(c, b->right, &rvtype);
3433 ### Expressions: Comparison
3435 Of slightly higher precedence that Boolean expressions are Comparisons.
3436 A comparison takes arguments of any comparable type, but the two types
3439 To simplify the parsing we introduce an `eop` which can record an
3440 expression operator, and the `CMPop` non-terminal will match one of them.
3447 ###### ast functions
3448 static void free_eop(struct eop *e)
3462 ###### declare terminals
3463 $LEFT < > <= >= == != CMPop
3465 ###### expression grammar
3466 | Expression CMPop Expression ${ {
3467 struct binode *b = new(binode);
3477 CMPop -> < ${ $0.op = Less; }$
3478 | > ${ $0.op = Gtr; }$
3479 | <= ${ $0.op = LessEq; }$
3480 | >= ${ $0.op = GtrEq; }$
3481 | == ${ $0.op = Eql; }$
3482 | != ${ $0.op = NEql; }$
3484 ###### print binode cases
3492 if (bracket) printf("(");
3493 print_exec(b->left, -1, bracket);
3495 case Less: printf(" < "); break;
3496 case LessEq: printf(" <= "); break;
3497 case Gtr: printf(" > "); break;
3498 case GtrEq: printf(" >= "); break;
3499 case Eql: printf(" == "); break;
3500 case NEql: printf(" != "); break;
3501 default: abort(); // NOTEST
3503 print_exec(b->right, -1, bracket);
3504 if (bracket) printf(")");
3507 ###### propagate binode cases
3514 /* Both must match but not be labels, result is Tbool */
3515 t = propagate_types(b->left, c, ok, NULL, Rnolabel);
3517 propagate_types(b->right, c, ok, t, 0);
3519 t = propagate_types(b->right, c, ok, NULL, Rnolabel); // UNTESTED
3521 t = propagate_types(b->left, c, ok, t, 0); // UNTESTED
3523 if (!type_compat(type, Tbool, 0))
3524 type_err(c, "error: Comparison returns %1 but %2 expected", prog,
3525 Tbool, rules, type);
3528 ###### interp binode cases
3537 left = interp_exec(c, b->left, <ype);
3538 right = interp_exec(c, b->right, &rtype);
3539 cmp = value_cmp(ltype, rtype, &left, &right);
3542 case Less: rv.bool = cmp < 0; break;
3543 case LessEq: rv.bool = cmp <= 0; break;
3544 case Gtr: rv.bool = cmp > 0; break;
3545 case GtrEq: rv.bool = cmp >= 0; break;
3546 case Eql: rv.bool = cmp == 0; break;
3547 case NEql: rv.bool = cmp != 0; break;
3548 default: rv.bool = 0; break; // NOTEST
3553 ### Expressions: Arithmetic etc.
3555 The remaining expressions with the highest precedence are arithmetic,
3556 string concatenation, and string conversion. String concatenation
3557 (`++`) has the same precedence as multiplication and division, but lower
3560 String conversion is a temporary feature until I get a better type
3561 system. `$` is a prefix operator which expects a string and returns
3564 `+` and `-` are both infix and prefix operations (where they are
3565 absolute value and negation). These have different operator names.
3567 We also have a 'Bracket' operator which records where parentheses were
3568 found. This makes it easy to reproduce these when printing. Possibly I
3569 should only insert brackets were needed for precedence. Putting
3570 parentheses around an expression converts it into a Term,
3580 ###### declare terminals
3586 ###### expression grammar
3587 | Expression Eop Expression ${ {
3588 struct binode *b = new(binode);
3595 | Expression Top Expression ${ {
3596 struct binode *b = new(binode);
3603 | Uop Expression ${ {
3604 struct binode *b = new(binode);
3612 | ( Expression ) ${ {
3613 struct binode *b = new_pos(binode, $1);
3622 Eop -> + ${ $0.op = Plus; }$
3623 | - ${ $0.op = Minus; }$
3625 Uop -> + ${ $0.op = Absolute; }$
3626 | - ${ $0.op = Negate; }$
3627 | $ ${ $0.op = StringConv; }$
3629 Top -> * ${ $0.op = Times; }$
3630 | / ${ $0.op = Divide; }$
3631 | % ${ $0.op = Rem; }$
3632 | ++ ${ $0.op = Concat; }$
3634 ###### print binode cases
3641 if (bracket) printf("(");
3642 print_exec(b->left, indent, bracket);
3644 case Plus: fputs(" + ", stdout); break;
3645 case Minus: fputs(" - ", stdout); break;
3646 case Times: fputs(" * ", stdout); break;
3647 case Divide: fputs(" / ", stdout); break;
3648 case Rem: fputs(" % ", stdout); break;
3649 case Concat: fputs(" ++ ", stdout); break;
3650 default: abort(); // NOTEST
3652 print_exec(b->right, indent, bracket);
3653 if (bracket) printf(")");
3658 if (bracket) printf("(");
3660 case Absolute: fputs("+", stdout); break;
3661 case Negate: fputs("-", stdout); break;
3662 case StringConv: fputs("$", stdout); break;
3663 default: abort(); // NOTEST
3665 print_exec(b->right, indent, bracket);
3666 if (bracket) printf(")");
3670 print_exec(b->right, indent, bracket);
3674 ###### propagate binode cases
3680 /* both must be numbers, result is Tnum */
3683 /* as propagate_types ignores a NULL,
3684 * unary ops fit here too */
3685 propagate_types(b->left, c, ok, Tnum, 0);
3686 propagate_types(b->right, c, ok, Tnum, 0);
3687 if (!type_compat(type, Tnum, 0))
3688 type_err(c, "error: Arithmetic returns %1 but %2 expected", prog,
3693 /* both must be Tstr, result is Tstr */
3694 propagate_types(b->left, c, ok, Tstr, 0);
3695 propagate_types(b->right, c, ok, Tstr, 0);
3696 if (!type_compat(type, Tstr, 0))
3697 type_err(c, "error: Concat returns %1 but %2 expected", prog,
3702 /* op must be string, result is number */
3703 propagate_types(b->left, c, ok, Tstr, 0);
3704 if (!type_compat(type, Tnum, 0))
3705 type_err(c, // UNTESTED
3706 "error: Can only convert string to number, not %1",
3707 prog, type, 0, NULL);
3711 return propagate_types(b->right, c, ok, type, 0);
3713 ###### interp binode cases
3716 rv = interp_exec(c, b->left, &rvtype);
3717 right = interp_exec(c, b->right, &rtype);
3718 mpq_add(rv.num, rv.num, right.num);
3721 rv = interp_exec(c, b->left, &rvtype);
3722 right = interp_exec(c, b->right, &rtype);
3723 mpq_sub(rv.num, rv.num, right.num);
3726 rv = interp_exec(c, b->left, &rvtype);
3727 right = interp_exec(c, b->right, &rtype);
3728 mpq_mul(rv.num, rv.num, right.num);
3731 rv = interp_exec(c, b->left, &rvtype);
3732 right = interp_exec(c, b->right, &rtype);
3733 mpq_div(rv.num, rv.num, right.num);
3738 left = interp_exec(c, b->left, <ype);
3739 right = interp_exec(c, b->right, &rtype);
3740 mpz_init(l); mpz_init(r); mpz_init(rem);
3741 mpz_tdiv_q(l, mpq_numref(left.num), mpq_denref(left.num));
3742 mpz_tdiv_q(r, mpq_numref(right.num), mpq_denref(right.num));
3743 mpz_tdiv_r(rem, l, r);
3744 val_init(Tnum, &rv);
3745 mpq_set_z(rv.num, rem);
3746 mpz_clear(r); mpz_clear(l); mpz_clear(rem);
3751 rv = interp_exec(c, b->right, &rvtype);
3752 mpq_neg(rv.num, rv.num);
3755 rv = interp_exec(c, b->right, &rvtype);
3756 mpq_abs(rv.num, rv.num);
3759 rv = interp_exec(c, b->right, &rvtype);
3762 left = interp_exec(c, b->left, <ype);
3763 right = interp_exec(c, b->right, &rtype);
3765 rv.str = text_join(left.str, right.str);
3768 right = interp_exec(c, b->right, &rvtype);
3772 struct text tx = right.str;
3775 if (tx.txt[0] == '-') {
3776 neg = 1; // UNTESTED
3777 tx.txt++; // UNTESTED
3778 tx.len--; // UNTESTED
3780 if (number_parse(rv.num, tail, tx) == 0)
3781 mpq_init(rv.num); // UNTESTED
3783 mpq_neg(rv.num, rv.num); // UNTESTED
3785 printf("Unsupported suffix: %.*s\n", tx.len, tx.txt); // UNTESTED
3789 ###### value functions
3791 static struct text text_join(struct text a, struct text b)
3794 rv.len = a.len + b.len;
3795 rv.txt = malloc(rv.len);
3796 memcpy(rv.txt, a.txt, a.len);
3797 memcpy(rv.txt+a.len, b.txt, b.len);
3801 ### Blocks, Statements, and Statement lists.
3803 Now that we have expressions out of the way we need to turn to
3804 statements. There are simple statements and more complex statements.
3805 Simple statements do not contain (syntactic) newlines, complex statements do.
3807 Statements often come in sequences and we have corresponding simple
3808 statement lists and complex statement lists.
3809 The former comprise only simple statements separated by semicolons.
3810 The later comprise complex statements and simple statement lists. They are
3811 separated by newlines. Thus the semicolon is only used to separate
3812 simple statements on the one line. This may be overly restrictive,
3813 but I'm not sure I ever want a complex statement to share a line with
3816 Note that a simple statement list can still use multiple lines if
3817 subsequent lines are indented, so
3819 ###### Example: wrapped simple statement list
3824 is a single simple statement list. This might allow room for
3825 confusion, so I'm not set on it yet.
3827 A simple statement list needs no extra syntax. A complex statement
3828 list has two syntactic forms. It can be enclosed in braces (much like
3829 C blocks), or it can be introduced by an indent and continue until an
3830 unindented newline (much like Python blocks). With this extra syntax
3831 it is referred to as a block.
3833 Note that a block does not have to include any newlines if it only
3834 contains simple statements. So both of:
3836 if condition: a=b; d=f
3838 if condition { a=b; print f }
3842 In either case the list is constructed from a `binode` list with
3843 `Block` as the operator. When parsing the list it is most convenient
3844 to append to the end, so a list is a list and a statement. When using
3845 the list it is more convenient to consider a list to be a statement
3846 and a list. So we need a function to re-order a list.
3847 `reorder_bilist` serves this purpose.
3849 The only stand-alone statement we introduce at this stage is `pass`
3850 which does nothing and is represented as a `NULL` pointer in a `Block`
3851 list. Other stand-alone statements will follow once the infrastructure
3854 As many statements will use binodes, we declare a binode pointer 'b' in
3855 the common header for all reductions to use.
3857 ###### Parser: reduce
3868 Block -> { IN OptNL Statementlist OUT OptNL } ${ $0 = $<Sl; }$
3869 | { SimpleStatements } ${ $0 = reorder_bilist($<SS); }$
3870 | SimpleStatements ; ${ $0 = reorder_bilist($<SS); }$
3871 | SimpleStatements EOL ${ $0 = reorder_bilist($<SS); }$
3872 | IN OptNL Statementlist OUT ${ $0 = $<Sl; }$
3874 OpenBlock -> OpenScope { IN OptNL Statementlist OUT OptNL } ${ $0 = $<Sl; }$
3875 | OpenScope { SimpleStatements } ${ $0 = reorder_bilist($<SS); }$
3876 | OpenScope SimpleStatements ; ${ $0 = reorder_bilist($<SS); }$
3877 | OpenScope SimpleStatements EOL ${ $0 = reorder_bilist($<SS); }$
3878 | IN OpenScope OptNL Statementlist OUT ${ $0 = $<Sl; }$
3880 UseBlock -> { OpenScope IN OptNL Statementlist OUT OptNL } ${ $0 = $<Sl; }$
3881 | { OpenScope SimpleStatements } ${ $0 = reorder_bilist($<SS); }$
3882 | IN OpenScope OptNL Statementlist OUT ${ $0 = $<Sl; }$
3884 ColonBlock -> { IN OptNL Statementlist OUT OptNL } ${ $0 = $<Sl; }$
3885 | { SimpleStatements } ${ $0 = reorder_bilist($<SS); }$
3886 | : SimpleStatements ; ${ $0 = reorder_bilist($<SS); }$
3887 | : SimpleStatements EOL ${ $0 = reorder_bilist($<SS); }$
3888 | : IN OptNL Statementlist OUT ${ $0 = $<Sl; }$
3890 Statementlist -> ComplexStatements ${ $0 = reorder_bilist($<CS); }$
3892 ComplexStatements -> ComplexStatements ComplexStatement ${
3902 | ComplexStatement ${
3914 ComplexStatement -> SimpleStatements Newlines ${
3915 $0 = reorder_bilist($<SS);
3917 | SimpleStatements ; Newlines ${
3918 $0 = reorder_bilist($<SS);
3920 ## ComplexStatement Grammar
3923 SimpleStatements -> SimpleStatements ; SimpleStatement ${
3929 | SimpleStatement ${
3938 SimpleStatement -> pass ${ $0 = NULL; }$
3939 | ERROR ${ tok_err(c, "Syntax error in statement", &$1); }$
3940 ## SimpleStatement Grammar
3942 ###### print binode cases
3946 if (b->left == NULL) // UNTESTED
3947 printf("pass"); // UNTESTED
3949 print_exec(b->left, indent, bracket); // UNTESTED
3950 if (b->right) { // UNTESTED
3951 printf("; "); // UNTESTED
3952 print_exec(b->right, indent, bracket); // UNTESTED
3955 // block, one per line
3956 if (b->left == NULL)
3957 do_indent(indent, "pass\n");
3959 print_exec(b->left, indent, bracket);
3961 print_exec(b->right, indent, bracket);
3965 ###### propagate binode cases
3968 /* If any statement returns something other than Tnone
3969 * or Tbool then all such must return same type.
3970 * As each statement may be Tnone or something else,
3971 * we must always pass NULL (unknown) down, otherwise an incorrect
3972 * error might occur. We never return Tnone unless it is
3977 for (e = b; e; e = cast(binode, e->right)) {
3978 t = propagate_types(e->left, c, ok, NULL, rules);
3979 if ((rules & Rboolok) && (t == Tbool || t == Tnone))
3981 if (t == Tnone && e->right)
3982 /* Only the final statement *must* return a value
3990 type_err(c, "error: expected %1%r, found %2",
3991 e->left, type, rules, t);
3997 ###### interp binode cases
3999 while (rvtype == Tnone &&
4002 rv = interp_exec(c, b->left, &rvtype);
4003 b = cast(binode, b->right);
4007 ### The Print statement
4009 `print` is a simple statement that takes a comma-separated list of
4010 expressions and prints the values separated by spaces and terminated
4011 by a newline. No control of formatting is possible.
4013 `print` uses `ExpressionList` to collect the expressions and stores them
4014 on the left side of a `Print` binode unlessthere is a trailing comma
4015 when the list is stored on the `right` side and no trailing newline is
4021 ##### declare terminals
4024 ###### SimpleStatement Grammar
4026 | print ExpressionList ${
4027 $0 = b = new(binode);
4030 b->left = reorder_bilist($<EL);
4032 | print ExpressionList , ${ {
4033 $0 = b = new(binode);
4035 b->right = reorder_bilist($<EL);
4039 $0 = b = new(binode);
4045 ###### print binode cases
4048 do_indent(indent, "print");
4050 print_exec(b->right, -1, bracket);
4053 print_exec(b->left, -1, bracket);
4058 ###### propagate binode cases
4061 /* don't care but all must be consistent */
4063 b = cast(binode, b->left);
4065 b = cast(binode, b->right);
4067 propagate_types(b->left, c, ok, NULL, Rnolabel);
4068 b = cast(binode, b->right);
4072 ###### interp binode cases
4076 struct binode *b2 = cast(binode, b->left);
4078 b2 = cast(binode, b->right);
4079 for (; b2; b2 = cast(binode, b2->right)) {
4080 left = interp_exec(c, b2->left, <ype);
4081 print_value(ltype, &left, stdout);
4082 free_value(ltype, &left);
4086 if (b->right == NULL)
4092 ###### Assignment statement
4094 An assignment will assign a value to a variable, providing it hasn't
4095 been declared as a constant. The analysis phase ensures that the type
4096 will be correct so the interpreter just needs to perform the
4097 calculation. There is a form of assignment which declares a new
4098 variable as well as assigning a value. If a name is assigned before
4099 it is declared, and error will be raised as the name is created as
4100 `Tlabel` and it is illegal to assign to such names.
4106 ###### declare terminals
4109 ###### SimpleStatement Grammar
4110 | Term = Expression ${
4111 $0 = b= new(binode);
4116 | VariableDecl = Expression ${
4117 $0 = b= new(binode);
4124 if ($1->var->where_set == NULL) {
4126 "Variable declared with no type or value: %v",
4130 $0 = b = new(binode);
4137 ###### print binode cases
4140 do_indent(indent, "");
4141 print_exec(b->left, indent, bracket);
4143 print_exec(b->right, indent, bracket);
4150 struct variable *v = cast(var, b->left)->var;
4151 do_indent(indent, "");
4152 print_exec(b->left, indent, bracket);
4153 if (cast(var, b->left)->var->constant) {
4155 if (v->explicit_type) {
4156 type_print(v->type, stdout);
4161 if (v->explicit_type) {
4162 type_print(v->type, stdout);
4168 print_exec(b->right, indent, bracket);
4175 ###### propagate binode cases
4179 /* Both must match and not be labels,
4180 * Type must support 'dup',
4181 * For Assign, left must not be constant.
4184 t = propagate_types(b->left, c, ok, NULL,
4185 Rnolabel | (b->op == Assign ? Rnoconstant : 0));
4190 if (propagate_types(b->right, c, ok, t, 0) != t)
4191 if (b->left->type == Xvar)
4192 type_err(c, "info: variable '%v' was set as %1 here.",
4193 cast(var, b->left)->var->where_set, t, rules, NULL);
4195 t = propagate_types(b->right, c, ok, NULL, Rnolabel);
4197 propagate_types(b->left, c, ok, t,
4198 (b->op == Assign ? Rnoconstant : 0));
4200 if (t && t->dup == NULL && t->name.txt[0] != ' ') // HACK
4201 type_err(c, "error: cannot assign value of type %1", b, t, 0, NULL);
4206 ###### interp binode cases
4209 lleft = linterp_exec(c, b->left, <ype);
4211 dinterp_exec(c, b->right, lleft, ltype, 1);
4217 struct variable *v = cast(var, b->left)->var;
4220 val = var_value(c, v);
4221 if (v->type->prepare_type)
4222 v->type->prepare_type(c, v->type, 0);
4224 dinterp_exec(c, b->right, val, v->type, 0);
4226 val_init(v->type, val);
4230 ### The `use` statement
4232 The `use` statement is the last "simple" statement. It is needed when a
4233 statement block can return a value. This includes the body of a
4234 function which has a return type, and the "condition" code blocks in
4235 `if`, `while`, and `switch` statements.
4240 ###### declare terminals
4243 ###### SimpleStatement Grammar
4245 $0 = b = new_pos(binode, $1);
4248 if (b->right->type == Xvar) {
4249 struct var *v = cast(var, b->right);
4250 if (v->var->type == Tnone) {
4251 /* Convert this to a label */
4254 v->var->type = Tlabel;
4255 val = global_alloc(c, Tlabel, v->var, NULL);
4261 ###### print binode cases
4264 do_indent(indent, "use ");
4265 print_exec(b->right, -1, bracket);
4270 ###### propagate binode cases
4273 /* result matches value */
4274 return propagate_types(b->right, c, ok, type, 0);
4276 ###### interp binode cases
4279 rv = interp_exec(c, b->right, &rvtype);
4282 ### The Conditional Statement
4284 This is the biggy and currently the only complex statement. This
4285 subsumes `if`, `while`, `do/while`, `switch`, and some parts of `for`.
4286 It is comprised of a number of parts, all of which are optional though
4287 set combinations apply. Each part is (usually) a key word (`then` is
4288 sometimes optional) followed by either an expression or a code block,
4289 except the `casepart` which is a "key word and an expression" followed
4290 by a code block. The code-block option is valid for all parts and,
4291 where an expression is also allowed, the code block can use the `use`
4292 statement to report a value. If the code block does not report a value
4293 the effect is similar to reporting `True`.
4295 The `else` and `case` parts, as well as `then` when combined with
4296 `if`, can contain a `use` statement which will apply to some
4297 containing conditional statement. `for` parts, `do` parts and `then`
4298 parts used with `for` can never contain a `use`, except in some
4299 subordinate conditional statement.
4301 If there is a `forpart`, it is executed first, only once.
4302 If there is a `dopart`, then it is executed repeatedly providing
4303 always that the `condpart` or `cond`, if present, does not return a non-True
4304 value. `condpart` can fail to return any value if it simply executes
4305 to completion. This is treated the same as returning `True`.
4307 If there is a `thenpart` it will be executed whenever the `condpart`
4308 or `cond` returns True (or does not return any value), but this will happen
4309 *after* `dopart` (when present).
4311 If `elsepart` is present it will be executed at most once when the
4312 condition returns `False` or some value that isn't `True` and isn't
4313 matched by any `casepart`. If there are any `casepart`s, they will be
4314 executed when the condition returns a matching value.
4316 The particular sorts of values allowed in case parts has not yet been
4317 determined in the language design, so nothing is prohibited.
4319 The various blocks in this complex statement potentially provide scope
4320 for variables as described earlier. Each such block must include the
4321 "OpenScope" nonterminal before parsing the block, and must call
4322 `var_block_close()` when closing the block.
4324 The code following "`if`", "`switch`" and "`for`" does not get its own
4325 scope, but is in a scope covering the whole statement, so names
4326 declared there cannot be redeclared elsewhere. Similarly the
4327 condition following "`while`" is in a scope the covers the body
4328 ("`do`" part) of the loop, and which does not allow conditional scope
4329 extension. Code following "`then`" (both looping and non-looping),
4330 "`else`" and "`case`" each get their own local scope.
4332 The type requirements on the code block in a `whilepart` are quite
4333 unusal. It is allowed to return a value of some identifiable type, in
4334 which case the loop aborts and an appropriate `casepart` is run, or it
4335 can return a Boolean, in which case the loop either continues to the
4336 `dopart` (on `True`) or aborts and runs the `elsepart` (on `False`).
4337 This is different both from the `ifpart` code block which is expected to
4338 return a Boolean, or the `switchpart` code block which is expected to
4339 return the same type as the casepart values. The correct analysis of
4340 the type of the `whilepart` code block is the reason for the
4341 `Rboolok` flag which is passed to `propagate_types()`.
4343 The `cond_statement` cannot fit into a `binode` so a new `exec` is
4344 defined. As there are two scopes which cover multiple parts - one for
4345 the whole statement and one for "while" and "do" - and as we will use
4346 the 'struct exec' to track scopes, we actually need two new types of
4347 exec. One is a `binode` for the looping part, the rest is the
4348 `cond_statement`. The `cond_statement` will use an auxilliary `struct
4349 casepart` to track a list of case parts.
4360 struct exec *action;
4361 struct casepart *next;
4363 struct cond_statement {
4365 struct exec *forpart, *condpart, *thenpart, *elsepart;
4366 struct binode *looppart;
4367 struct casepart *casepart;
4370 ###### ast functions
4372 static void free_casepart(struct casepart *cp)
4376 free_exec(cp->value);
4377 free_exec(cp->action);
4384 static void free_cond_statement(struct cond_statement *s)
4388 free_exec(s->forpart);
4389 free_exec(s->condpart);
4390 free_exec(s->looppart);
4391 free_exec(s->thenpart);
4392 free_exec(s->elsepart);
4393 free_casepart(s->casepart);
4397 ###### free exec cases
4398 case Xcond_statement: free_cond_statement(cast(cond_statement, e)); break;
4400 ###### ComplexStatement Grammar
4401 | CondStatement ${ $0 = $<1; }$
4403 ###### declare terminals
4404 $TERM for then while do
4411 // A CondStatement must end with EOL, as does CondSuffix and
4413 // ForPart, ThenPart, SwitchPart, CasePart are non-empty and
4414 // may or may not end with EOL
4415 // WhilePart and IfPart include an appropriate Suffix
4417 // ForPart, SwitchPart, and IfPart open scopes, o we have to close
4418 // them. WhilePart opens and closes its own scope.
4419 CondStatement -> ForPart OptNL ThenPart OptNL WhilePart CondSuffix ${
4422 $0->thenpart = $<TP;
4423 $0->looppart = $<WP;
4424 var_block_close(c, CloseSequential, $0);
4426 | ForPart OptNL WhilePart CondSuffix ${
4429 $0->looppart = $<WP;
4430 var_block_close(c, CloseSequential, $0);
4432 | WhilePart CondSuffix ${
4434 $0->looppart = $<WP;
4436 | SwitchPart OptNL CasePart CondSuffix ${
4438 $0->condpart = $<SP;
4439 $CP->next = $0->casepart;
4440 $0->casepart = $<CP;
4441 var_block_close(c, CloseSequential, $0);
4443 | SwitchPart : IN OptNL CasePart CondSuffix OUT Newlines ${
4445 $0->condpart = $<SP;
4446 $CP->next = $0->casepart;
4447 $0->casepart = $<CP;
4448 var_block_close(c, CloseSequential, $0);
4450 | IfPart IfSuffix ${
4452 $0->condpart = $IP.condpart; $IP.condpart = NULL;
4453 $0->thenpart = $IP.thenpart; $IP.thenpart = NULL;
4454 // This is where we close an "if" statement
4455 var_block_close(c, CloseSequential, $0);
4458 CondSuffix -> IfSuffix ${
4461 | Newlines CasePart CondSuffix ${
4463 $CP->next = $0->casepart;
4464 $0->casepart = $<CP;
4466 | CasePart CondSuffix ${
4468 $CP->next = $0->casepart;
4469 $0->casepart = $<CP;
4472 IfSuffix -> Newlines ${ $0 = new(cond_statement); }$
4473 | Newlines ElsePart ${ $0 = $<EP; }$
4474 | ElsePart ${$0 = $<EP; }$
4476 ElsePart -> else OpenBlock Newlines ${
4477 $0 = new(cond_statement);
4478 $0->elsepart = $<OB;
4479 var_block_close(c, CloseElse, $0->elsepart);
4481 | else OpenScope CondStatement ${
4482 $0 = new(cond_statement);
4483 $0->elsepart = $<CS;
4484 var_block_close(c, CloseElse, $0->elsepart);
4488 CasePart -> case Expression OpenScope ColonBlock ${
4489 $0 = calloc(1,sizeof(struct casepart));
4492 var_block_close(c, CloseParallel, $0->action);
4496 // These scopes are closed in CondStatement
4497 ForPart -> for OpenBlock ${
4501 ThenPart -> then OpenBlock ${
4503 var_block_close(c, CloseSequential, $0);
4507 // This scope is closed in CondStatement
4508 WhilePart -> while UseBlock OptNL do OpenBlock ${
4513 var_block_close(c, CloseSequential, $0->right);
4514 var_block_close(c, CloseSequential, $0);
4516 | while OpenScope Expression OpenScope ColonBlock ${
4521 var_block_close(c, CloseSequential, $0->right);
4522 var_block_close(c, CloseSequential, $0);
4526 IfPart -> if UseBlock OptNL then OpenBlock ${
4529 var_block_close(c, CloseParallel, $0.thenpart);
4531 | if OpenScope Expression OpenScope ColonBlock ${
4534 var_block_close(c, CloseParallel, $0.thenpart);
4536 | if OpenScope Expression OpenScope OptNL then Block ${
4539 var_block_close(c, CloseParallel, $0.thenpart);
4543 // This scope is closed in CondStatement
4544 SwitchPart -> switch OpenScope Expression ${
4547 | switch UseBlock ${
4551 ###### print binode cases
4553 if (b->left && b->left->type == Xbinode &&
4554 cast(binode, b->left)->op == Block) {
4556 do_indent(indent, "while {\n");
4558 do_indent(indent, "while\n");
4559 print_exec(b->left, indent+1, bracket);
4561 do_indent(indent, "} do {\n");
4563 do_indent(indent, "do\n");
4564 print_exec(b->right, indent+1, bracket);
4566 do_indent(indent, "}\n");
4568 do_indent(indent, "while ");
4569 print_exec(b->left, 0, bracket);
4574 print_exec(b->right, indent+1, bracket);
4576 do_indent(indent, "}\n");
4580 ###### print exec cases
4582 case Xcond_statement:
4584 struct cond_statement *cs = cast(cond_statement, e);
4585 struct casepart *cp;
4587 do_indent(indent, "for");
4588 if (bracket) printf(" {\n"); else printf("\n");
4589 print_exec(cs->forpart, indent+1, bracket);
4592 do_indent(indent, "} then {\n");
4594 do_indent(indent, "then\n");
4595 print_exec(cs->thenpart, indent+1, bracket);
4597 if (bracket) do_indent(indent, "}\n");
4600 print_exec(cs->looppart, indent, bracket);
4604 do_indent(indent, "switch");
4606 do_indent(indent, "if");
4607 if (cs->condpart && cs->condpart->type == Xbinode &&
4608 cast(binode, cs->condpart)->op == Block) {
4613 print_exec(cs->condpart, indent+1, bracket);
4615 do_indent(indent, "}\n");
4617 do_indent(indent, "then\n");
4618 print_exec(cs->thenpart, indent+1, bracket);
4622 print_exec(cs->condpart, 0, bracket);
4628 print_exec(cs->thenpart, indent+1, bracket);
4630 do_indent(indent, "}\n");
4635 for (cp = cs->casepart; cp; cp = cp->next) {
4636 do_indent(indent, "case ");
4637 print_exec(cp->value, -1, 0);
4642 print_exec(cp->action, indent+1, bracket);
4644 do_indent(indent, "}\n");
4647 do_indent(indent, "else");
4652 print_exec(cs->elsepart, indent+1, bracket);
4654 do_indent(indent, "}\n");
4659 ###### propagate binode cases
4661 t = propagate_types(b->right, c, ok, Tnone, 0);
4662 if (!type_compat(Tnone, t, 0))
4663 *ok = 0; // UNTESTED
4664 return propagate_types(b->left, c, ok, type, rules);
4666 ###### propagate exec cases
4667 case Xcond_statement:
4669 // forpart and looppart->right must return Tnone
4670 // thenpart must return Tnone if there is a loopart,
4671 // otherwise it is like elsepart.
4673 // be bool if there is no casepart
4674 // match casepart->values if there is a switchpart
4675 // either be bool or match casepart->value if there
4677 // elsepart and casepart->action must match the return type
4678 // expected of this statement.
4679 struct cond_statement *cs = cast(cond_statement, prog);
4680 struct casepart *cp;
4682 t = propagate_types(cs->forpart, c, ok, Tnone, 0);
4683 if (!type_compat(Tnone, t, 0))
4684 *ok = 0; // UNTESTED
4687 t = propagate_types(cs->thenpart, c, ok, Tnone, 0);
4688 if (!type_compat(Tnone, t, 0))
4689 *ok = 0; // UNTESTED
4691 if (cs->casepart == NULL) {
4692 propagate_types(cs->condpart, c, ok, Tbool, 0);
4693 propagate_types(cs->looppart, c, ok, Tbool, 0);
4695 /* Condpart must match case values, with bool permitted */
4697 for (cp = cs->casepart;
4698 cp && !t; cp = cp->next)
4699 t = propagate_types(cp->value, c, ok, NULL, 0);
4700 if (!t && cs->condpart)
4701 t = propagate_types(cs->condpart, c, ok, NULL, Rboolok); // UNTESTED
4702 if (!t && cs->looppart)
4703 t = propagate_types(cs->looppart, c, ok, NULL, Rboolok); // UNTESTED
4704 // Now we have a type (I hope) push it down
4706 for (cp = cs->casepart; cp; cp = cp->next)
4707 propagate_types(cp->value, c, ok, t, 0);
4708 propagate_types(cs->condpart, c, ok, t, Rboolok);
4709 propagate_types(cs->looppart, c, ok, t, Rboolok);
4712 // (if)then, else, and case parts must return expected type.
4713 if (!cs->looppart && !type)
4714 type = propagate_types(cs->thenpart, c, ok, NULL, rules);
4716 type = propagate_types(cs->elsepart, c, ok, NULL, rules);
4717 for (cp = cs->casepart;
4719 cp = cp->next) // UNTESTED
4720 type = propagate_types(cp->action, c, ok, NULL, rules); // UNTESTED
4723 propagate_types(cs->thenpart, c, ok, type, rules);
4724 propagate_types(cs->elsepart, c, ok, type, rules);
4725 for (cp = cs->casepart; cp ; cp = cp->next)
4726 propagate_types(cp->action, c, ok, type, rules);
4732 ###### interp binode cases
4734 // This just performs one iterration of the loop
4735 rv = interp_exec(c, b->left, &rvtype);
4736 if (rvtype == Tnone ||
4737 (rvtype == Tbool && rv.bool != 0))
4738 // rvtype is Tnone or Tbool, doesn't need to be freed
4739 interp_exec(c, b->right, NULL);
4742 ###### interp exec cases
4743 case Xcond_statement:
4745 struct value v, cnd;
4746 struct type *vtype, *cndtype;
4747 struct casepart *cp;
4748 struct cond_statement *cs = cast(cond_statement, e);
4751 interp_exec(c, cs->forpart, NULL);
4753 while ((cnd = interp_exec(c, cs->looppart, &cndtype)),
4754 cndtype == Tnone || (cndtype == Tbool && cnd.bool != 0))
4755 interp_exec(c, cs->thenpart, NULL);
4757 cnd = interp_exec(c, cs->condpart, &cndtype);
4758 if ((cndtype == Tnone ||
4759 (cndtype == Tbool && cnd.bool != 0))) {
4760 // cnd is Tnone or Tbool, doesn't need to be freed
4761 rv = interp_exec(c, cs->thenpart, &rvtype);
4762 // skip else (and cases)
4766 for (cp = cs->casepart; cp; cp = cp->next) {
4767 v = interp_exec(c, cp->value, &vtype);
4768 if (value_cmp(cndtype, vtype, &v, &cnd) == 0) {
4769 free_value(vtype, &v);
4770 free_value(cndtype, &cnd);
4771 rv = interp_exec(c, cp->action, &rvtype);
4774 free_value(vtype, &v);
4776 free_value(cndtype, &cnd);
4778 rv = interp_exec(c, cs->elsepart, &rvtype);
4785 ### Top level structure
4787 All the language elements so far can be used in various places. Now
4788 it is time to clarify what those places are.
4790 At the top level of a file there will be a number of declarations.
4791 Many of the things that can be declared haven't been described yet,
4792 such as functions, procedures, imports, and probably more.
4793 For now there are two sorts of things that can appear at the top
4794 level. They are predefined constants, `struct` types, and the `main`
4795 function. While the syntax will allow the `main` function to appear
4796 multiple times, that will trigger an error if it is actually attempted.
4798 The various declarations do not return anything. They store the
4799 various declarations in the parse context.
4801 ###### Parser: grammar
4804 Ocean -> OptNL DeclarationList
4806 ## declare terminals
4814 DeclarationList -> Declaration
4815 | DeclarationList Declaration
4817 Declaration -> ERROR Newlines ${
4818 tok_err(c, // UNTESTED
4819 "error: unhandled parse error", &$1);
4825 ## top level grammar
4829 ### The `const` section
4831 As well as being defined in with the code that uses them, constants
4832 can be declared at the top level. These have full-file scope, so they
4833 are always `InScope`. The value of a top level constant can be given
4834 as an expression, and this is evaluated immediately rather than in the
4835 later interpretation stage. Once we add functions to the language, we
4836 will need rules concern which, if any, can be used to define a top
4839 Constants are defined in a section that starts with the reserved word
4840 `const` and then has a block with a list of assignment statements.
4841 For syntactic consistency, these must use the double-colon syntax to
4842 make it clear that they are constants. Type can also be given: if
4843 not, the type will be determined during analysis, as with other
4846 As the types constants are inserted at the head of a list, printing
4847 them in the same order that they were read is not straight forward.
4848 We take a quadratic approach here and count the number of constants
4849 (variables of depth 0), then count down from there, each time
4850 searching through for the Nth constant for decreasing N.
4852 ###### top level grammar
4856 DeclareConstant -> const { IN OptNL ConstList OUT OptNL } Newlines
4857 | const { SimpleConstList } Newlines
4858 | const IN OptNL ConstList OUT Newlines
4859 | const SimpleConstList Newlines
4861 ConstList -> ConstList SimpleConstLine
4864 SimpleConstList -> SimpleConstList ; Const
4868 SimpleConstLine -> SimpleConstList Newlines
4869 | ERROR Newlines ${ tok_err(c, "Syntax error in constant", &$1); }$
4872 CType -> Type ${ $0 = $<1; }$
4876 Const -> IDENTIFIER :: CType = Expression ${ {
4880 v = var_decl(c, $1.txt);
4882 struct var *var = new_pos(var, $1);
4883 v->where_decl = var;
4889 struct variable *vorig = var_ref(c, $1.txt);
4890 tok_err(c, "error: name already declared", &$1);
4891 type_err(c, "info: this is where '%v' was first declared",
4892 vorig->where_decl, NULL, 0, NULL);
4896 propagate_types($5, c, &ok, $3, 0);
4901 struct value res = interp_exec(c, $5, &v->type);
4902 global_alloc(c, v->type, v, &res);
4906 ###### print const decls
4911 while (target != 0) {
4913 for (v = context.in_scope; v; v=v->in_scope)
4914 if (v->depth == 0 && v->constant) {
4925 struct value *val = var_value(&context, v);
4926 printf(" %.*s :: ", v->name->name.len, v->name->name.txt);
4927 type_print(v->type, stdout);
4929 if (v->type == Tstr)
4931 print_value(v->type, val, stdout);
4932 if (v->type == Tstr)
4940 ### Function declarations
4942 The code in an Ocean program is all stored in function declarations.
4943 One of the functions must be named `main` and it must accept an array of
4944 strings as a parameter - the command line arguments.
4946 As this is the top level, several things are handled a bit differently.
4947 The function is not interpreted by `interp_exec` as that isn't passed
4948 the argument list which the program requires. Similarly type analysis
4949 is a bit more interesting at this level.
4951 ###### ast functions
4953 static struct type *handle_results(struct parse_context *c,
4954 struct binode *results)
4956 /* Create a 'struct' type from the results list, which
4957 * is a list for 'struct var'
4959 struct type *t = add_anon_type(c, &structure_prototype,
4960 " function result");
4964 for (b = results; b; b = cast(binode, b->right))
4966 t->structure.nfields = cnt;
4967 t->structure.fields = calloc(cnt, sizeof(struct field));
4969 for (b = results; b; b = cast(binode, b->right)) {
4970 struct var *v = cast(var, b->left);
4971 struct field *f = &t->structure.fields[cnt++];
4972 int a = v->var->type->align;
4973 f->name = v->var->name->name;
4974 f->type = v->var->type;
4976 f->offset = t->size;
4977 v->var->frame_pos = f->offset;
4978 t->size += ((f->type->size - 1) | (a-1)) + 1;
4981 variable_unlink_exec(v->var);
4983 free_binode(results);
4987 static struct variable *declare_function(struct parse_context *c,
4988 struct variable *name,
4989 struct binode *args,
4991 struct binode *results,
4995 struct value fn = {.function = code};
4997 var_block_close(c, CloseFunction, code);
4998 t = add_anon_type(c, &function_prototype,
4999 "func %.*s", name->name->name.len,
5000 name->name->name.txt);
5002 t->function.params = reorder_bilist(args);
5004 ret = handle_results(c, reorder_bilist(results));
5005 t->function.inline_result = 1;
5006 t->function.local_size = ret->size;
5008 t->function.return_type = ret;
5009 global_alloc(c, t, name, &fn);
5010 name->type->function.scope = c->out_scope;
5015 var_block_close(c, CloseFunction, NULL);
5017 c->out_scope = NULL;
5021 ###### declare terminals
5024 ###### top level grammar
5027 DeclareFunction -> func FuncName ( OpenScope ArgsLine ) Block Newlines ${
5028 $0 = declare_function(c, $<FN, $<Ar, Tnone, NULL, $<Bl);
5030 | func FuncName IN OpenScope Args OUT OptNL do Block Newlines ${
5031 $0 = declare_function(c, $<FN, $<Ar, Tnone, NULL, $<Bl);
5033 | func FuncName NEWLINE OpenScope OptNL do Block Newlines ${
5034 $0 = declare_function(c, $<FN, NULL, Tnone, NULL, $<Bl);
5036 | func FuncName ( OpenScope ArgsLine ) : Type Block Newlines ${
5037 $0 = declare_function(c, $<FN, $<Ar, $<Ty, NULL, $<Bl);
5039 | func FuncName ( OpenScope ArgsLine ) : ( ArgsLine ) Block Newlines ${
5040 $0 = declare_function(c, $<FN, $<AL, NULL, $<AL2, $<Bl);
5042 | func FuncName IN OpenScope Args OUT OptNL return Type Newlines do Block Newlines ${
5043 $0 = declare_function(c, $<FN, $<Ar, $<Ty, NULL, $<Bl);
5045 | func FuncName NEWLINE OpenScope return Type Newlines do Block Newlines ${
5046 $0 = declare_function(c, $<FN, NULL, $<Ty, NULL, $<Bl);
5048 | func FuncName IN OpenScope Args OUT OptNL return IN Args OUT OptNL do Block Newlines ${
5049 $0 = declare_function(c, $<FN, $<Ar, NULL, $<Ar2, $<Bl);
5051 | func FuncName NEWLINE OpenScope return IN Args OUT OptNL do Block Newlines ${
5052 $0 = declare_function(c, $<FN, NULL, NULL, $<Ar, $<Bl);
5055 ###### print func decls
5060 while (target != 0) {
5062 for (v = context.in_scope; v; v=v->in_scope)
5063 if (v->depth == 0 && v->type && v->type->check_args) {
5072 struct value *val = var_value(&context, v);
5073 printf("func %.*s", v->name->name.len, v->name->name.txt);
5074 v->type->print_type_decl(v->type, stdout);
5076 print_exec(val->function, 0, brackets);
5078 print_value(v->type, val, stdout);
5079 printf("/* frame size %d */\n", v->type->function.local_size);
5085 ###### core functions
5087 static int analyse_funcs(struct parse_context *c)
5091 for (v = c->in_scope; v; v = v->in_scope) {
5095 if (v->depth != 0 || !v->type || !v->type->check_args)
5097 ret = v->type->function.inline_result ?
5098 Tnone : v->type->function.return_type;
5099 val = var_value(c, v);
5102 propagate_types(val->function, c, &ok, ret, 0);
5105 /* Make sure everything is still consistent */
5106 propagate_types(val->function, c, &ok, ret, 0);
5109 if (!v->type->function.inline_result &&
5110 !v->type->function.return_type->dup) {
5111 type_err(c, "error: function cannot return value of type %1",
5112 v->where_decl, v->type->function.return_type, 0, NULL);
5115 scope_finalize(c, v->type);
5120 static int analyse_main(struct type *type, struct parse_context *c)
5122 struct binode *bp = type->function.params;
5126 struct type *argv_type;
5128 argv_type = add_anon_type(c, &array_prototype, "argv");
5129 argv_type->array.member = Tstr;
5130 argv_type->array.unspec = 1;
5132 for (b = bp; b; b = cast(binode, b->right)) {
5136 propagate_types(b->left, c, &ok, argv_type, 0);
5138 default: /* invalid */ // NOTEST
5139 propagate_types(b->left, c, &ok, Tnone, 0); // NOTEST
5145 return !c->parse_error;
5148 static void interp_main(struct parse_context *c, int argc, char **argv)
5150 struct value *progp = NULL;
5151 struct text main_name = { "main", 4 };
5152 struct variable *mainv;
5158 mainv = var_ref(c, main_name);
5160 progp = var_value(c, mainv);
5161 if (!progp || !progp->function) {
5162 fprintf(stderr, "oceani: no main function found.\n");
5166 if (!analyse_main(mainv->type, c)) {
5167 fprintf(stderr, "oceani: main has wrong type.\n");
5171 al = mainv->type->function.params;
5173 c->local_size = mainv->type->function.local_size;
5174 c->local = calloc(1, c->local_size);
5176 struct var *v = cast(var, al->left);
5177 struct value *vl = var_value(c, v->var);
5187 mpq_set_ui(argcq, argc, 1);
5188 memcpy(var_value(c, t->array.vsize), &argcq, sizeof(argcq));
5189 t->prepare_type(c, t, 0);
5190 array_init(v->var->type, vl);
5191 for (i = 0; i < argc; i++) {
5192 struct value *vl2 = vl->array + i * v->var->type->array.member->size;
5194 arg.str.txt = argv[i];
5195 arg.str.len = strlen(argv[i]);
5196 free_value(Tstr, vl2);
5197 dup_value(Tstr, &arg, vl2);
5201 al = cast(binode, al->right);
5203 v = interp_exec(c, progp->function, &vtype);
5204 free_value(vtype, &v);
5209 ###### ast functions
5210 void free_variable(struct variable *v)
5214 ## And now to test it out.
5216 Having a language requires having a "hello world" program. I'll
5217 provide a little more than that: a program that prints "Hello world"
5218 finds the GCD of two numbers, prints the first few elements of
5219 Fibonacci, performs a binary search for a number, and a few other
5220 things which will likely grow as the languages grows.
5222 ###### File: oceani.mk
5225 @echo "===== DEMO ====="
5226 ./oceani --section "demo: hello" oceani.mdc 55 33
5232 four ::= 2 + 2 ; five ::= 10/2
5233 const pie ::= "I like Pie";
5234 cake ::= "The cake is"
5242 func main(argv:[argc::]string)
5243 print "Hello World, what lovely oceans you have!"
5244 print "Are there", five, "?"
5245 print pi, pie, "but", cake
5247 A := $argv[1]; B := $argv[2]
5249 /* When a variable is defined in both branches of an 'if',
5250 * and used afterwards, the variables are merged.
5256 print "Is", A, "bigger than", B,"? ", bigger
5257 /* If a variable is not used after the 'if', no
5258 * merge happens, so types can be different
5261 double:string = "yes"
5262 print A, "is more than twice", B, "?", double
5265 print "double", B, "is", double
5270 if a > 0 and then b > 0:
5276 print "GCD of", A, "and", B,"is", a
5278 print a, "is not positive, cannot calculate GCD"
5280 print b, "is not positive, cannot calculate GCD"
5285 print "Fibonacci:", f1,f2,
5286 then togo = togo - 1
5294 /* Binary search... */
5299 mid := (lo + hi) / 2
5312 print "Yay, I found", target
5314 print "Closest I found was", lo
5319 // "middle square" PRNG. Not particularly good, but one my
5320 // Dad taught me - the first one I ever heard of.
5321 for i:=1; then i = i + 1; while i < size:
5322 n := list[i-1] * list[i-1]
5323 list[i] = (n / 100) % 10 000
5325 print "Before sort:",
5326 for i:=0; then i = i + 1; while i < size:
5330 for i := 1; then i=i+1; while i < size:
5331 for j:=i-1; then j=j-1; while j >= 0:
5332 if list[j] > list[j+1]:
5336 print " After sort:",
5337 for i:=0; then i = i + 1; while i < size:
5341 if 1 == 2 then print "yes"; else print "no"
5345 bob.alive = (bob.name == "Hello")
5346 print "bob", "is" if bob.alive else "isn't", "alive"