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);
1196 $0 = new_val(Tnum, $1);
1199 if (number_parse($0->val.num, tail, $1.txt) == 0)
1200 mpq_init($0->val.num); // UNTESTED
1202 tok_err(c, "error: unsupported number suffix",
1207 $0 = new_val(Tstr, $1);
1210 string_parse(&$1, '\\', &$0->val.str, tail);
1212 tok_err(c, "error: unsupported string suffix",
1217 $0 = new_val(Tstr, $1);
1220 string_parse(&$1, '\\', &$0->val.str, tail);
1222 tok_err(c, "error: unsupported string suffix",
1227 ###### print exec cases
1230 struct val *v = cast(val, e);
1231 if (v->vtype == Tstr)
1233 print_value(v->vtype, &v->val, stdout);
1234 if (v->vtype == Tstr)
1239 ###### propagate exec cases
1242 struct val *val = cast(val, prog);
1243 if (!type_compat(type, val->vtype, rules))
1244 type_err(c, "error: expected %1%r found %2",
1245 prog, type, rules, val->vtype);
1249 ###### interp exec cases
1251 rvtype = cast(val, e)->vtype;
1252 dup_value(rvtype, &cast(val, e)->val, &rv);
1255 ###### ast functions
1256 static void free_val(struct val *v)
1259 free_value(v->vtype, &v->val);
1263 ###### free exec cases
1264 case Xval: free_val(cast(val, e)); break;
1266 ###### ast functions
1267 // Move all nodes from 'b' to 'rv', reversing their order.
1268 // In 'b' 'left' is a list, and 'right' is the last node.
1269 // In 'rv', left' is the first node and 'right' is a list.
1270 static struct binode *reorder_bilist(struct binode *b)
1272 struct binode *rv = NULL;
1275 struct exec *t = b->right;
1279 b = cast(binode, b->left);
1289 Variables are scoped named values. We store the names in a linked list
1290 of "bindings" sorted in lexical order, and use sequential search and
1297 struct binding *next; // in lexical order
1301 This linked list is stored in the parse context so that "reduce"
1302 functions can find or add variables, and so the analysis phase can
1303 ensure that every variable gets a type.
1305 ###### parse context
1307 struct binding *varlist; // In lexical order
1309 ###### ast functions
1311 static struct binding *find_binding(struct parse_context *c, struct text s)
1313 struct binding **l = &c->varlist;
1318 (cmp = text_cmp((*l)->name, s)) < 0)
1322 n = calloc(1, sizeof(*n));
1329 Each name can be linked to multiple variables defined in different
1330 scopes. Each scope starts where the name is declared and continues
1331 until the end of the containing code block. Scopes of a given name
1332 cannot nest, so a declaration while a name is in-scope is an error.
1334 ###### binding fields
1335 struct variable *var;
1339 struct variable *previous;
1341 struct binding *name;
1342 struct exec *where_decl;// where name was declared
1343 struct exec *where_set; // where type was set
1347 When a scope closes, the values of the variables might need to be freed.
1348 This happens in the context of some `struct exec` and each `exec` will
1349 need to know which variables need to be freed when it completes.
1352 struct variable *to_free;
1354 ####### variable fields
1355 struct exec *cleanup_exec;
1356 struct variable *next_free;
1358 ####### interp exec cleanup
1361 for (v = e->to_free; v; v = v->next_free) {
1362 struct value *val = var_value(c, v);
1363 free_value(v->type, val);
1367 ###### ast functions
1368 static void variable_unlink_exec(struct variable *v)
1370 struct variable **vp;
1371 if (!v->cleanup_exec)
1373 for (vp = &v->cleanup_exec->to_free;
1374 *vp; vp = &(*vp)->next_free) {
1378 v->cleanup_exec = NULL;
1383 While the naming seems strange, we include local constants in the
1384 definition of variables. A name declared `var := value` can
1385 subsequently be changed, but a name declared `var ::= value` cannot -
1388 ###### variable fields
1391 Scopes in parallel branches can be partially merged. More
1392 specifically, if a given name is declared in both branches of an
1393 if/else then its scope is a candidate for merging. Similarly if
1394 every branch of an exhaustive switch (e.g. has an "else" clause)
1395 declares a given name, then the scopes from the branches are
1396 candidates for merging.
1398 Note that names declared inside a loop (which is only parallel to
1399 itself) are never visible after the loop. Similarly names defined in
1400 scopes which are not parallel, such as those started by `for` and
1401 `switch`, are never visible after the scope. Only variables defined in
1402 both `then` and `else` (including the implicit then after an `if`, and
1403 excluding `then` used with `for`) and in all `case`s and `else` of a
1404 `switch` or `while` can be visible beyond the `if`/`switch`/`while`.
1406 Labels, which are a bit like variables, follow different rules.
1407 Labels are not explicitly declared, but if an undeclared name appears
1408 in a context where a label is legal, that effectively declares the
1409 name as a label. The declaration remains in force (or in scope) at
1410 least to the end of the immediately containing block and conditionally
1411 in any larger containing block which does not declare the name in some
1412 other way. Importantly, the conditional scope extension happens even
1413 if the label is only used in one parallel branch of a conditional --
1414 when used in one branch it is treated as having been declared in all
1417 Merge candidates are tentatively visible beyond the end of the
1418 branching statement which creates them. If the name is used, the
1419 merge is affirmed and they become a single variable visible at the
1420 outer layer. If not - if it is redeclared first - the merge lapses.
1422 To track scopes we have an extra stack, implemented as a linked list,
1423 which roughly parallels the parse stack and which is used exclusively
1424 for scoping. When a new scope is opened, a new frame is pushed and
1425 the child-count of the parent frame is incremented. This child-count
1426 is used to distinguish between the first of a set of parallel scopes,
1427 in which declared variables must not be in scope, and subsequent
1428 branches, whether they may already be conditionally scoped.
1430 We need a total ordering of scopes so we can easily compare to variables
1431 to see if they are concurrently in scope. To achieve this we record a
1432 `scope_count` which is actually a count of both beginnings and endings
1433 of scopes. Then each variable has a record of the scope count where it
1434 enters scope, and where it leaves.
1436 To push a new frame *before* any code in the frame is parsed, we need a
1437 grammar reduction. This is most easily achieved with a grammar
1438 element which derives the empty string, and creates the new scope when
1439 it is recognised. This can be placed, for example, between a keyword
1440 like "if" and the code following it.
1444 struct scope *parent;
1448 ###### parse context
1451 struct scope *scope_stack;
1453 ###### variable fields
1454 int scope_start, scope_end;
1456 ###### ast functions
1457 static void scope_pop(struct parse_context *c)
1459 struct scope *s = c->scope_stack;
1461 c->scope_stack = s->parent;
1463 c->scope_depth -= 1;
1464 c->scope_count += 1;
1467 static void scope_push(struct parse_context *c)
1469 struct scope *s = calloc(1, sizeof(*s));
1471 c->scope_stack->child_count += 1;
1472 s->parent = c->scope_stack;
1474 c->scope_depth += 1;
1475 c->scope_count += 1;
1481 OpenScope -> ${ scope_push(c); }$
1483 Each variable records a scope depth and is in one of four states:
1485 - "in scope". This is the case between the declaration of the
1486 variable and the end of the containing block, and also between
1487 the usage with affirms a merge and the end of that block.
1489 The scope depth is not greater than the current parse context scope
1490 nest depth. When the block of that depth closes, the state will
1491 change. To achieve this, all "in scope" variables are linked
1492 together as a stack in nesting order.
1494 - "pending". The "in scope" block has closed, but other parallel
1495 scopes are still being processed. So far, every parallel block at
1496 the same level that has closed has declared the name.
1498 The scope depth is the depth of the last parallel block that
1499 enclosed the declaration, and that has closed.
1501 - "conditionally in scope". The "in scope" block and all parallel
1502 scopes have closed, and no further mention of the name has been seen.
1503 This state includes a secondary nest depth (`min_depth`) which records
1504 the outermost scope seen since the variable became conditionally in
1505 scope. If a use of the name is found, the variable becomes "in scope"
1506 and that secondary depth becomes the recorded scope depth. If the
1507 name is declared as a new variable, the old variable becomes "out of
1508 scope" and the recorded scope depth stays unchanged.
1510 - "out of scope". The variable is neither in scope nor conditionally
1511 in scope. It is permanently out of scope now and can be removed from
1512 the "in scope" stack. When a variable becomes out-of-scope it is
1513 moved to a separate list (`out_scope`) of variables which have fully
1514 known scope. This will be used at the end of each function to assign
1515 each variable a place in the stack frame.
1517 ###### variable fields
1518 int depth, min_depth;
1519 enum { OutScope, PendingScope, CondScope, InScope } scope;
1520 struct variable *in_scope;
1522 ###### parse context
1524 struct variable *in_scope;
1525 struct variable *out_scope;
1527 All variables with the same name are linked together using the
1528 'previous' link. Those variable that have been affirmatively merged all
1529 have a 'merged' pointer that points to one primary variable - the most
1530 recently declared instance. When merging variables, we need to also
1531 adjust the 'merged' pointer on any other variables that had previously
1532 been merged with the one that will no longer be primary.
1534 A variable that is no longer the most recent instance of a name may
1535 still have "pending" scope, if it might still be merged with most
1536 recent instance. These variables don't really belong in the
1537 "in_scope" list, but are not immediately removed when a new instance
1538 is found. Instead, they are detected and ignored when considering the
1539 list of in_scope names.
1541 The storage of the value of a variable will be described later. For now
1542 we just need to know that when a variable goes out of scope, it might
1543 need to be freed. For this we need to be able to find it, so assume that
1544 `var_value()` will provide that.
1546 ###### variable fields
1547 struct variable *merged;
1549 ###### ast functions
1551 static void variable_merge(struct variable *primary, struct variable *secondary)
1555 primary = primary->merged;
1557 for (v = primary->previous; v; v=v->previous)
1558 if (v == secondary || v == secondary->merged ||
1559 v->merged == secondary ||
1560 v->merged == secondary->merged) {
1561 v->scope = OutScope;
1562 v->merged = primary;
1563 if (v->scope_start < primary->scope_start)
1564 primary->scope_start = v->scope_start;
1565 if (v->scope_end > primary->scope_end)
1566 primary->scope_end = v->scope_end; // NOTEST
1567 variable_unlink_exec(v);
1571 ###### forward decls
1572 static struct value *var_value(struct parse_context *c, struct variable *v);
1574 ###### free global vars
1576 while (context.varlist) {
1577 struct binding *b = context.varlist;
1578 struct variable *v = b->var;
1579 context.varlist = b->next;
1582 struct variable *next = v->previous;
1585 free_value(v->type, var_value(&context, v));
1587 // This is a global constant
1588 free_exec(v->where_decl);
1595 #### Manipulating Bindings
1597 When a name is conditionally visible, a new declaration discards the old
1598 binding - the condition lapses. Similarly when we reach the end of a
1599 function (outermost non-global scope) any conditional scope must lapse.
1600 Conversely a usage of the name affirms the visibility and extends it to
1601 the end of the containing block - i.e. the block that contains both the
1602 original declaration and the latest usage. This is determined from
1603 `min_depth`. When a conditionally visible variable gets affirmed like
1604 this, it is also merged with other conditionally visible variables with
1607 When we parse a variable declaration we either report an error if the
1608 name is currently bound, or create a new variable at the current nest
1609 depth if the name is unbound or bound to a conditionally scoped or
1610 pending-scope variable. If the previous variable was conditionally
1611 scoped, it and its homonyms becomes out-of-scope.
1613 When we parse a variable reference (including non-declarative assignment
1614 "foo = bar") we report an error if the name is not bound or is bound to
1615 a pending-scope variable; update the scope if the name is bound to a
1616 conditionally scoped variable; or just proceed normally if the named
1617 variable is in scope.
1619 When we exit a scope, any variables bound at this level are either
1620 marked out of scope or pending-scoped, depending on whether the scope
1621 was sequential or parallel. Here a "parallel" scope means the "then"
1622 or "else" part of a conditional, or any "case" or "else" branch of a
1623 switch. Other scopes are "sequential".
1625 When exiting a parallel scope we check if there are any variables that
1626 were previously pending and are still visible. If there are, then
1627 they weren't redeclared in the most recent scope, so they cannot be
1628 merged and must become out-of-scope. If it is not the first of
1629 parallel scopes (based on `child_count`), we check that there was a
1630 previous binding that is still pending-scope. If there isn't, the new
1631 variable must now be out-of-scope.
1633 When exiting a sequential scope that immediately enclosed parallel
1634 scopes, we need to resolve any pending-scope variables. If there was
1635 no `else` clause, and we cannot determine that the `switch` was exhaustive,
1636 we need to mark all pending-scope variable as out-of-scope. Otherwise
1637 all pending-scope variables become conditionally scoped.
1640 enum closetype { CloseSequential, CloseFunction, CloseParallel, CloseElse };
1642 ###### ast functions
1644 static struct variable *var_decl(struct parse_context *c, struct text s)
1646 struct binding *b = find_binding(c, s);
1647 struct variable *v = b->var;
1649 switch (v ? v->scope : OutScope) {
1651 /* Caller will report the error */
1655 v && v->scope == CondScope;
1657 v->scope = OutScope;
1661 v = calloc(1, sizeof(*v));
1662 v->previous = b->var;
1666 v->min_depth = v->depth = c->scope_depth;
1668 v->in_scope = c->in_scope;
1669 v->scope_start = c->scope_count;
1675 static struct variable *var_ref(struct parse_context *c, struct text s)
1677 struct binding *b = find_binding(c, s);
1678 struct variable *v = b->var;
1679 struct variable *v2;
1681 switch (v ? v->scope : OutScope) {
1684 /* Caller will report the error */
1687 /* All CondScope variables of this name need to be merged
1688 * and become InScope
1690 v->depth = v->min_depth;
1692 for (v2 = v->previous;
1693 v2 && v2->scope == CondScope;
1695 variable_merge(v, v2);
1703 static int var_refile(struct parse_context *c, struct variable *v)
1705 /* Variable just went out of scope. Add it to the out_scope
1706 * list, sorted by ->scope_start
1708 struct variable **vp = &c->out_scope;
1709 while ((*vp) && (*vp)->scope_start < v->scope_start)
1710 vp = &(*vp)->in_scope;
1716 static void var_block_close(struct parse_context *c, enum closetype ct,
1719 /* Close off all variables that are in_scope.
1720 * Some variables in c->scope may already be not-in-scope,
1721 * such as when a PendingScope variable is hidden by a new
1722 * variable with the same name.
1723 * So we check for v->name->var != v and drop them.
1724 * If we choose to make a variable OutScope, we drop it
1727 struct variable *v, **vp, *v2;
1730 for (vp = &c->in_scope;
1731 (v = *vp) && v->min_depth > c->scope_depth;
1732 (v->scope == OutScope || v->name->var != v)
1733 ? (*vp = v->in_scope, var_refile(c, v))
1734 : ( vp = &v->in_scope, 0)) {
1735 v->min_depth = c->scope_depth;
1736 if (v->name->var != v)
1737 /* This is still in scope, but we haven't just
1741 v->min_depth = c->scope_depth;
1742 if (v->scope == InScope)
1743 v->scope_end = c->scope_count;
1744 if (v->scope == InScope && e && !v->global) {
1745 /* This variable gets cleaned up when 'e' finishes */
1746 variable_unlink_exec(v);
1747 v->cleanup_exec = e;
1748 v->next_free = e->to_free;
1753 case CloseParallel: /* handle PendingScope */
1757 if (c->scope_stack->child_count == 1)
1758 /* first among parallel branches */
1759 v->scope = PendingScope;
1760 else if (v->previous &&
1761 v->previous->scope == PendingScope)
1762 /* all previous branches used name */
1763 v->scope = PendingScope;
1764 else if (v->type == Tlabel)
1765 /* Labels remain pending even when not used */
1766 v->scope = PendingScope; // UNTESTED
1768 v->scope = OutScope;
1769 if (ct == CloseElse) {
1770 /* All Pending variables with this name
1771 * are now Conditional */
1773 v2 && v2->scope == PendingScope;
1775 v2->scope = CondScope;
1779 /* Not possible as it would require
1780 * parallel scope to be nested immediately
1781 * in a parallel scope, and that never
1785 /* Not possible as we already tested for
1792 if (v->scope == CondScope)
1793 /* Condition cannot continue past end of function */
1796 case CloseSequential:
1797 if (v->type == Tlabel)
1798 v->scope = PendingScope;
1801 v->scope = OutScope;
1804 /* There was no 'else', so we can only become
1805 * conditional if we know the cases were exhaustive,
1806 * and that doesn't mean anything yet.
1807 * So only labels become conditional..
1810 v2 && v2->scope == PendingScope;
1812 if (v2->type == Tlabel)
1813 v2->scope = CondScope;
1815 v2->scope = OutScope;
1818 case OutScope: break;
1827 The value of a variable is store separately from the variable, on an
1828 analogue of a stack frame. There are (currently) two frames that can be
1829 active. A global frame which currently only stores constants, and a
1830 stacked frame which stores local variables. Each variable knows if it
1831 is global or not, and what its index into the frame is.
1833 Values in the global frame are known immediately they are relevant, so
1834 the frame needs to be reallocated as it grows so it can store those
1835 values. The local frame doesn't get values until the interpreted phase
1836 is started, so there is no need to allocate until the size is known.
1838 We initialize the `frame_pos` to an impossible value, so that we can
1839 tell if it was set or not later.
1841 ###### variable fields
1845 ###### variable init
1848 ###### parse context
1850 short global_size, global_alloc;
1852 void *global, *local;
1854 ###### ast functions
1856 static struct value *var_value(struct parse_context *c, struct variable *v)
1859 if (!c->local || !v->type)
1860 return NULL; // NOTEST
1861 if (v->frame_pos + v->type->size > c->local_size) {
1862 printf("INVALID frame_pos\n"); // NOTEST
1865 return c->local + v->frame_pos;
1867 if (c->global_size > c->global_alloc) {
1868 int old = c->global_alloc;
1869 c->global_alloc = (c->global_size | 1023) + 1024;
1870 c->global = realloc(c->global, c->global_alloc);
1871 memset(c->global + old, 0, c->global_alloc - old);
1873 return c->global + v->frame_pos;
1876 static struct value *global_alloc(struct parse_context *c, struct type *t,
1877 struct variable *v, struct value *init)
1880 struct variable scratch;
1882 if (t->prepare_type)
1883 t->prepare_type(c, t, 1); // NOTEST
1885 if (c->global_size & (t->align - 1))
1886 c->global_size = (c->global_size + t->align) & ~(t->align-1);
1891 v->frame_pos = c->global_size;
1893 c->global_size += v->type->size;
1894 ret = var_value(c, v);
1896 memcpy(ret, init, t->size);
1902 As global values are found -- struct field initializers, labels etc --
1903 `global_alloc()` is called to record the value in the global frame.
1905 When the program is fully parsed, each function is analysed, we need to
1906 walk the list of variables local to that function and assign them an
1907 offset in the stack frame. For this we have `scope_finalize()`.
1909 We keep the stack from dense by re-using space for between variables
1910 that are not in scope at the same time. The `out_scope` list is sorted
1911 by `scope_start` and as we process a varible, we move it to an FIFO
1912 stack. For each variable we consider, we first discard any from the
1913 stack anything that went out of scope before the new variable came in.
1914 Then we place the new variable just after the one at the top of the
1917 ###### ast functions
1919 static void scope_finalize(struct parse_context *c, struct type *ft)
1921 int size = ft->function.local_size;
1922 struct variable *next = ft->function.scope;
1923 struct variable *done = NULL;
1926 struct variable *v = next;
1927 struct type *t = v->type;
1934 if (v->frame_pos >= 0)
1936 while (done && done->scope_end < v->scope_start)
1937 done = done->in_scope;
1939 pos = done->frame_pos + done->type->size;
1941 pos = ft->function.local_size;
1942 if (pos & (t->align - 1))
1943 pos = (pos + t->align) & ~(t->align-1);
1945 if (size < pos + v->type->size)
1946 size = pos + v->type->size;
1950 c->out_scope = NULL;
1951 ft->function.local_size = size;
1954 ###### free context storage
1955 free(context.global);
1957 #### Variables as executables
1959 Just as we used a `val` to wrap a value into an `exec`, we similarly
1960 need a `var` to wrap a `variable` into an exec. While each `val`
1961 contained a copy of the value, each `var` holds a link to the variable
1962 because it really is the same variable no matter where it appears.
1963 When a variable is used, we need to remember to follow the `->merged`
1964 link to find the primary instance.
1966 When a variable is declared, it may or may not be given an explicit
1967 type. We need to record which so that we can report the parsed code
1976 struct variable *var;
1979 ###### variable fields
1987 VariableDecl -> IDENTIFIER : ${ {
1988 struct variable *v = var_decl(c, $1.txt);
1989 $0 = new_pos(var, $1);
1994 v = var_ref(c, $1.txt);
1996 type_err(c, "error: variable '%v' redeclared",
1998 type_err(c, "info: this is where '%v' was first declared",
1999 v->where_decl, NULL, 0, NULL);
2002 | IDENTIFIER :: ${ {
2003 struct variable *v = var_decl(c, $1.txt);
2004 $0 = new_pos(var, $1);
2010 v = var_ref(c, $1.txt);
2012 type_err(c, "error: variable '%v' redeclared",
2014 type_err(c, "info: this is where '%v' was first declared",
2015 v->where_decl, NULL, 0, NULL);
2018 | IDENTIFIER : Type ${ {
2019 struct variable *v = var_decl(c, $1.txt);
2020 $0 = new_pos(var, $1);
2026 v->explicit_type = 1;
2028 v = var_ref(c, $1.txt);
2030 type_err(c, "error: variable '%v' redeclared",
2032 type_err(c, "info: this is where '%v' was first declared",
2033 v->where_decl, NULL, 0, NULL);
2036 | IDENTIFIER :: Type ${ {
2037 struct variable *v = var_decl(c, $1.txt);
2038 $0 = new_pos(var, $1);
2045 v->explicit_type = 1;
2047 v = var_ref(c, $1.txt);
2049 type_err(c, "error: variable '%v' redeclared",
2051 type_err(c, "info: this is where '%v' was first declared",
2052 v->where_decl, NULL, 0, NULL);
2057 Variable -> IDENTIFIER ${ {
2058 struct variable *v = var_ref(c, $1.txt);
2059 $0 = new_pos(var, $1);
2061 /* This might be a label - allocate a var just in case */
2062 v = var_decl(c, $1.txt);
2069 cast(var, $0)->var = v;
2072 ###### print exec cases
2075 struct var *v = cast(var, e);
2077 struct binding *b = v->var->name;
2078 printf("%.*s", b->name.len, b->name.txt);
2085 if (loc && loc->type == Xvar) {
2086 struct var *v = cast(var, loc);
2088 struct binding *b = v->var->name;
2089 fprintf(stderr, "%.*s", b->name.len, b->name.txt);
2091 fputs("???", stderr); // NOTEST
2093 fputs("NOTVAR", stderr);
2096 ###### propagate exec cases
2100 struct var *var = cast(var, prog);
2101 struct variable *v = var->var;
2103 type_err(c, "%d:BUG: no variable!!", prog, NULL, 0, NULL); // NOTEST
2104 return Tnone; // NOTEST
2107 if (v->constant && (rules & Rnoconstant)) {
2108 type_err(c, "error: Cannot assign to a constant: %v",
2109 prog, NULL, 0, NULL);
2110 type_err(c, "info: name was defined as a constant here",
2111 v->where_decl, NULL, 0, NULL);
2114 if (v->type == Tnone && v->where_decl == prog)
2115 type_err(c, "error: variable used but not declared: %v",
2116 prog, NULL, 0, NULL);
2117 if (v->type == NULL) {
2118 if (type && *ok != 0) {
2120 v->where_set = prog;
2125 if (!type_compat(type, v->type, rules)) {
2126 type_err(c, "error: expected %1%r but variable '%v' is %2", prog,
2127 type, rules, v->type);
2128 type_err(c, "info: this is where '%v' was set to %1", v->where_set,
2129 v->type, rules, NULL);
2136 ###### interp exec cases
2139 struct var *var = cast(var, e);
2140 struct variable *v = var->var;
2143 lrv = var_value(c, v);
2148 ###### ast functions
2150 static void free_var(struct var *v)
2155 ###### free exec cases
2156 case Xvar: free_var(cast(var, e)); break;
2161 Now that we have the shape of the interpreter in place we can add some
2162 complex types and connected them in to the data structures and the
2163 different phases of parse, analyse, print, interpret.
2165 Being "complex" the language will naturally have syntax to access
2166 specifics of objects of these types. These will fit into the grammar as
2167 "Terms" which are the things that are combined with various operators to
2168 form "Expression". Where a Term is formed by some operation on another
2169 Term, the subordinate Term will always come first, so for example a
2170 member of an array will be expressed as the Term for the array followed
2171 by an index in square brackets. The strict rule of using postfix
2172 operations makes precedence irrelevant within terms. To provide a place
2173 to put the grammar for each terms of each type, we will start out by
2174 introducing the "Term" grammar production, with contains at least a
2175 simple "Value" (to be explained later).
2179 Term -> Value ${ $0 = $<1; }$
2180 | Variable ${ $0 = $<1; }$
2183 Thus far the complex types we have are arrays and structs.
2187 Arrays can be declared by giving a size and a type, as `[size]type' so
2188 `freq:[26]number` declares `freq` to be an array of 26 numbers. The
2189 size can be either a literal number, or a named constant. Some day an
2190 arbitrary expression will be supported.
2192 As a formal parameter to a function, the array can be declared with a
2193 new variable as the size: `name:[size::number]string`. The `size`
2194 variable is set to the size of the array and must be a constant. As
2195 `number` is the only supported type, it can be left out:
2196 `name:[size::]string`.
2198 Arrays cannot be assigned. When pointers are introduced we will also
2199 introduce array slices which can refer to part or all of an array -
2200 the assignment syntax will create a slice. For now, an array can only
2201 ever be referenced by the name it is declared with. It is likely that
2202 a "`copy`" primitive will eventually be define which can be used to
2203 make a copy of an array with controllable recursive depth.
2205 For now we have two sorts of array, those with fixed size either because
2206 it is given as a literal number or because it is a struct member (which
2207 cannot have a runtime-changing size), and those with a size that is
2208 determined at runtime - local variables with a const size. The former
2209 have their size calculated at parse time, the latter at run time.
2211 For the latter type, the `size` field of the type is the size of a
2212 pointer, and the array is reallocated every time it comes into scope.
2214 We differentiate struct fields with a const size from local variables
2215 with a const size by whether they are prepared at parse time or not.
2217 ###### type union fields
2220 int unspec; // size is unspecified - vsize must be set.
2223 struct variable *vsize;
2224 struct type *member;
2227 ###### value union fields
2228 void *array; // used if not static_size
2230 ###### value functions
2232 static void array_prepare_type(struct parse_context *c, struct type *type,
2235 struct value *vsize;
2237 if (!type->array.vsize || type->array.static_size)
2240 vsize = var_value(c, type->array.vsize);
2242 mpz_tdiv_q(q, mpq_numref(vsize->num), mpq_denref(vsize->num));
2243 type->array.size = mpz_get_si(q);
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;
2365 t->array.static_size = 1;
2366 t->size = t->array.size * t->array.member->size;
2367 t->align = t->array.member->align;
2370 | [ IDENTIFIER ] Type ${ {
2371 struct variable *v = var_ref(c, $2.txt);
2374 tok_err(c, "error: name undeclared", &$2);
2375 else if (!v->constant)
2376 tok_err(c, "error: array size must be a constant", &$2);
2378 $0 = add_anon_type(c, &array_prototype, "array[%.*s]", $2.txt.len, $2.txt.txt);
2379 $0->array.member = $<4;
2381 $0->array.vsize = v;
2386 OptType -> Type ${ $0 = $<1; }$
2389 ###### formal type grammar
2391 | [ IDENTIFIER :: OptType ] Type ${ {
2392 struct variable *v = var_decl(c, $ID.txt);
2398 $0 = add_anon_type(c, &array_prototype, "array[var]");
2399 $0->array.member = $<6;
2401 $0->array.unspec = 1;
2402 $0->array.vsize = v;
2410 | Term [ Expression ] ${ {
2411 struct binode *b = new(binode);
2418 ###### print binode cases
2420 print_exec(b->left, -1, bracket);
2422 print_exec(b->right, -1, bracket);
2426 ###### propagate binode cases
2428 /* left must be an array, right must be a number,
2429 * result is the member type of the array
2431 propagate_types(b->right, c, ok, Tnum, 0);
2432 t = propagate_types(b->left, c, ok, NULL, rules & Rnoconstant);
2433 if (!t || t->compat != array_compat) {
2434 type_err(c, "error: %1 cannot be indexed", prog, t, 0, NULL);
2437 if (!type_compat(type, t->array.member, rules)) {
2438 type_err(c, "error: have %1 but need %2", prog,
2439 t->array.member, rules, type);
2441 return t->array.member;
2445 ###### interp binode cases
2451 lleft = linterp_exec(c, b->left, <ype);
2452 right = interp_exec(c, b->right, &rtype);
2454 mpz_tdiv_q(q, mpq_numref(right.num), mpq_denref(right.num));
2458 if (ltype->array.static_size)
2461 ptr = *(void**)lleft;
2462 rvtype = ltype->array.member;
2463 if (i >= 0 && i < ltype->array.size)
2464 lrv = ptr + i * rvtype->size;
2466 val_init(ltype->array.member, &rv); // UNSAFE
2473 A `struct` is a data-type that contains one or more other data-types.
2474 It differs from an array in that each member can be of a different
2475 type, and they are accessed by name rather than by number. Thus you
2476 cannot choose an element by calculation, you need to know what you
2479 The language makes no promises about how a given structure will be
2480 stored in memory - it is free to rearrange fields to suit whatever
2481 criteria seems important.
2483 Structs are declared separately from program code - they cannot be
2484 declared in-line in a variable declaration like arrays can. A struct
2485 is given a name and this name is used to identify the type - the name
2486 is not prefixed by the word `struct` as it would be in C.
2488 Structs are only treated as the same if they have the same name.
2489 Simply having the same fields in the same order is not enough. This
2490 might change once we can create structure initializers from a list of
2493 Each component datum is identified much like a variable is declared,
2494 with a name, one or two colons, and a type. The type cannot be omitted
2495 as there is no opportunity to deduce the type from usage. An initial
2496 value can be given following an equals sign, so
2498 ##### Example: a struct type
2504 would declare a type called "complex" which has two number fields,
2505 each initialised to zero.
2507 Struct will need to be declared separately from the code that uses
2508 them, so we will need to be able to print out the declaration of a
2509 struct when reprinting the whole program. So a `print_type_decl` type
2510 function will be needed.
2512 ###### type union fields
2524 ###### type functions
2525 void (*print_type_decl)(struct type *type, FILE *f);
2527 ###### value functions
2529 static void structure_init(struct type *type, struct value *val)
2533 for (i = 0; i < type->structure.nfields; i++) {
2535 v = (void*) val->ptr + type->structure.fields[i].offset;
2536 if (type->structure.fields[i].init)
2537 dup_value(type->structure.fields[i].type,
2538 type->structure.fields[i].init,
2541 val_init(type->structure.fields[i].type, v);
2545 static void structure_free(struct type *type, struct value *val)
2549 for (i = 0; i < type->structure.nfields; i++) {
2551 v = (void*)val->ptr + type->structure.fields[i].offset;
2552 free_value(type->structure.fields[i].type, v);
2556 static void structure_free_type(struct type *t)
2559 for (i = 0; i < t->structure.nfields; i++)
2560 if (t->structure.fields[i].init) {
2561 free_value(t->structure.fields[i].type,
2562 t->structure.fields[i].init);
2564 free(t->structure.fields);
2567 static struct type structure_prototype = {
2568 .init = structure_init,
2569 .free = structure_free,
2570 .free_type = structure_free_type,
2571 .print_type_decl = structure_print_type,
2585 ###### free exec cases
2587 free_exec(cast(fieldref, e)->left);
2591 ###### declare terminals
2596 | Term . IDENTIFIER ${ {
2597 struct fieldref *fr = new_pos(fieldref, $2);
2604 ###### print exec cases
2608 struct fieldref *f = cast(fieldref, e);
2609 print_exec(f->left, -1, bracket);
2610 printf(".%.*s", f->name.len, f->name.txt);
2614 ###### ast functions
2615 static int find_struct_index(struct type *type, struct text field)
2618 for (i = 0; i < type->structure.nfields; i++)
2619 if (text_cmp(type->structure.fields[i].name, field) == 0)
2624 ###### propagate exec cases
2628 struct fieldref *f = cast(fieldref, prog);
2629 struct type *st = propagate_types(f->left, c, ok, NULL, 0);
2632 type_err(c, "error: unknown type for field access", f->left, // UNTESTED
2634 else if (st->init != structure_init)
2635 type_err(c, "error: field reference attempted on %1, not a struct",
2636 f->left, st, 0, NULL);
2637 else if (f->index == -2) {
2638 f->index = find_struct_index(st, f->name);
2640 type_err(c, "error: cannot find requested field in %1",
2641 f->left, st, 0, NULL);
2643 if (f->index >= 0) {
2644 struct type *ft = st->structure.fields[f->index].type;
2645 if (!type_compat(type, ft, rules))
2646 type_err(c, "error: have %1 but need %2", prog,
2653 ###### interp exec cases
2656 struct fieldref *f = cast(fieldref, e);
2658 struct value *lleft = linterp_exec(c, f->left, <ype);
2659 lrv = (void*)lleft->ptr + ltype->structure.fields[f->index].offset;
2660 rvtype = ltype->structure.fields[f->index].type;
2666 struct fieldlist *prev;
2670 ###### ast functions
2671 static void free_fieldlist(struct fieldlist *f)
2675 free_fieldlist(f->prev);
2677 free_value(f->f.type, f->f.init); // UNTESTED
2678 free(f->f.init); // UNTESTED
2683 ###### top level grammar
2684 DeclareStruct -> struct IDENTIFIER FieldBlock Newlines ${ {
2686 add_type(c, $2.txt, &structure_prototype);
2688 struct fieldlist *f;
2690 for (f = $3; f; f=f->prev)
2693 t->structure.nfields = cnt;
2694 t->structure.fields = calloc(cnt, sizeof(struct field));
2697 int a = f->f.type->align;
2699 t->structure.fields[cnt] = f->f;
2700 if (t->size & (a-1))
2701 t->size = (t->size | (a-1)) + 1;
2702 t->structure.fields[cnt].offset = t->size;
2703 t->size += ((f->f.type->size - 1) | (a-1)) + 1;
2712 FieldBlock -> { IN OptNL FieldLines OUT OptNL } ${ $0 = $<FL; }$
2713 | { SimpleFieldList } ${ $0 = $<SFL; }$
2714 | IN OptNL FieldLines OUT ${ $0 = $<FL; }$
2715 | SimpleFieldList EOL ${ $0 = $<SFL; }$
2717 FieldLines -> SimpleFieldList Newlines ${ $0 = $<SFL; }$
2718 | FieldLines SimpleFieldList Newlines ${
2723 SimpleFieldList -> Field ${ $0 = $<F; }$
2724 | SimpleFieldList ; Field ${
2728 | SimpleFieldList ; ${
2731 | ERROR ${ tok_err(c, "Syntax error in struct field", &$1); }$
2733 Field -> IDENTIFIER : Type = Expression ${ {
2736 $0 = calloc(1, sizeof(struct fieldlist));
2737 $0->f.name = $1.txt;
2742 propagate_types($<5, c, &ok, $3, 0);
2745 c->parse_error = 1; // UNTESTED
2747 struct value vl = interp_exec(c, $5, NULL);
2748 $0->f.init = global_alloc(c, $0->f.type, NULL, &vl);
2751 | IDENTIFIER : Type ${
2752 $0 = calloc(1, sizeof(struct fieldlist));
2753 $0->f.name = $1.txt;
2755 if ($0->f.type->prepare_type)
2756 $0->f.type->prepare_type(c, $0->f.type, 1);
2759 ###### forward decls
2760 static void structure_print_type(struct type *t, FILE *f);
2762 ###### value functions
2763 static void structure_print_type(struct type *t, FILE *f)
2767 fprintf(f, "struct %.*s\n", t->name.len, t->name.txt);
2769 for (i = 0; i < t->structure.nfields; i++) {
2770 struct field *fl = t->structure.fields + i;
2771 fprintf(f, " %.*s : ", fl->name.len, fl->name.txt);
2772 type_print(fl->type, f);
2773 if (fl->type->print && fl->init) {
2775 if (fl->type == Tstr)
2776 fprintf(f, "\""); // UNTESTED
2777 print_value(fl->type, fl->init, f);
2778 if (fl->type == Tstr)
2779 fprintf(f, "\""); // UNTESTED
2785 ###### print type decls
2790 while (target != 0) {
2792 for (t = context.typelist; t ; t=t->next)
2793 if (!t->anon && t->print_type_decl &&
2803 t->print_type_decl(t, stdout);
2811 A function is a chunk of code which can be passed parameters and can
2812 return results. Each function has a type which includes the set of
2813 parameters and the return value. As yet these types cannot be declared
2814 separately from the function itself.
2816 The parameters can be specified either in parentheses as a ';' separated
2819 ##### Example: function 1
2821 func main(av:[ac::number]string; env:[envc::number]string)
2824 or as an indented list of one parameter per line (though each line can
2825 be a ';' separated list)
2827 ##### Example: function 2
2830 argv:[argc::number]string
2831 env:[envc::number]string
2835 In the first case a return type can follow the parentheses after a colon,
2836 in the second it is given on a line starting with the word `return`.
2838 ##### Example: functions that return
2840 func add(a:number; b:number): number
2850 Rather than returning a type, the function can specify a set of local
2851 variables to return as a struct. The values of these variables when the
2852 function exits will be provided to the caller. For this the return type
2853 is replaced with a block of result declarations, either in parentheses
2854 or bracketed by `return` and `do`.
2856 ##### Example: functions returning multiple variables
2858 func to_cartesian(rho:number; theta:number):(x:number; y:number)
2871 For constructing the lists we use a `List` binode, which will be
2872 further detailed when Expression Lists are introduced.
2874 ###### type union fields
2877 struct binode *params;
2878 struct type *return_type;
2879 struct variable *scope;
2880 int inline_result; // return value is at start of 'local'
2884 ###### value union fields
2885 struct exec *function;
2887 ###### type functions
2888 void (*check_args)(struct parse_context *c, int *ok,
2889 struct type *require, struct exec *args);
2891 ###### value functions
2893 static void function_free(struct type *type, struct value *val)
2895 free_exec(val->function);
2896 val->function = NULL;
2899 static int function_compat(struct type *require, struct type *have)
2901 // FIXME can I do anything here yet?
2905 static void function_check_args(struct parse_context *c, int *ok,
2906 struct type *require, struct exec *args)
2908 /* This should be 'compat', but we don't have a 'tuple' type to
2909 * hold the type of 'args'
2911 struct binode *arg = cast(binode, args);
2912 struct binode *param = require->function.params;
2915 struct var *pv = cast(var, param->left);
2917 type_err(c, "error: insufficient arguments to function.",
2918 args, NULL, 0, NULL);
2922 propagate_types(arg->left, c, ok, pv->var->type, 0);
2923 param = cast(binode, param->right);
2924 arg = cast(binode, arg->right);
2927 type_err(c, "error: too many arguments to function.",
2928 args, NULL, 0, NULL);
2931 static void function_print(struct type *type, struct value *val, FILE *f)
2933 print_exec(val->function, 1, 0);
2936 static void function_print_type_decl(struct type *type, FILE *f)
2940 for (b = type->function.params; b; b = cast(binode, b->right)) {
2941 struct variable *v = cast(var, b->left)->var;
2942 fprintf(f, "%.*s%s", v->name->name.len, v->name->name.txt,
2943 v->constant ? "::" : ":");
2944 type_print(v->type, f);
2949 if (type->function.return_type != Tnone) {
2951 if (type->function.inline_result) {
2953 struct type *t = type->function.return_type;
2955 for (i = 0; i < t->structure.nfields; i++) {
2956 struct field *fl = t->structure.fields + i;
2959 fprintf(f, "%.*s:", fl->name.len, fl->name.txt);
2960 type_print(fl->type, f);
2964 type_print(type->function.return_type, f);
2969 static void function_free_type(struct type *t)
2971 free_exec(t->function.params);
2974 static struct type function_prototype = {
2975 .size = sizeof(void*),
2976 .align = sizeof(void*),
2977 .free = function_free,
2978 .compat = function_compat,
2979 .check_args = function_check_args,
2980 .print = function_print,
2981 .print_type_decl = function_print_type_decl,
2982 .free_type = function_free_type,
2985 ###### declare terminals
2995 FuncName -> IDENTIFIER ${ {
2996 struct variable *v = var_decl(c, $1.txt);
2997 struct var *e = new_pos(var, $1);
3003 v = var_ref(c, $1.txt);
3005 type_err(c, "error: function '%v' redeclared",
3007 type_err(c, "info: this is where '%v' was first declared",
3008 v->where_decl, NULL, 0, NULL);
3014 Args -> ArgsLine NEWLINE ${ $0 = $<AL; }$
3015 | Args ArgsLine NEWLINE ${ {
3016 struct binode *b = $<AL;
3017 struct binode **bp = &b;
3019 bp = (struct binode **)&(*bp)->left;
3024 ArgsLine -> ${ $0 = NULL; }$
3025 | Varlist ${ $0 = $<1; }$
3026 | Varlist ; ${ $0 = $<1; }$
3028 Varlist -> Varlist ; ArgDecl ${
3042 ArgDecl -> IDENTIFIER : FormalType ${ {
3043 struct variable *v = var_decl(c, $1.txt);
3049 ##### Function calls
3051 A function call can appear either as an expression or as a statement.
3052 We use a new 'Funcall' binode type to link the function with a list of
3053 arguments, form with the 'List' nodes.
3055 We have already seen the "Term" which is how a function call can appear
3056 in an expression. To parse a function call into a statement we include
3057 it in the "SimpleStatement Grammar" which will be described later.
3063 | Term ( ExpressionList ) ${ {
3064 struct binode *b = new(binode);
3067 b->right = reorder_bilist($<EL);
3071 struct binode *b = new(binode);
3078 ###### SimpleStatement Grammar
3080 | Term ( ExpressionList ) ${ {
3081 struct binode *b = new(binode);
3084 b->right = reorder_bilist($<EL);
3088 ###### print binode cases
3091 do_indent(indent, "");
3092 print_exec(b->left, -1, bracket);
3094 for (b = cast(binode, b->right); b; b = cast(binode, b->right)) {
3097 print_exec(b->left, -1, bracket);
3107 ###### propagate binode cases
3110 /* Every arg must match formal parameter, and result
3111 * is return type of function
3113 struct binode *args = cast(binode, b->right);
3114 struct var *v = cast(var, b->left);
3116 if (!v->var->type || v->var->type->check_args == NULL) {
3117 type_err(c, "error: attempt to call a non-function.",
3118 prog, NULL, 0, NULL);
3121 v->var->type->check_args(c, ok, v->var->type, args);
3122 return v->var->type->function.return_type;
3125 ###### interp binode cases
3128 struct var *v = cast(var, b->left);
3129 struct type *t = v->var->type;
3130 void *oldlocal = c->local;
3131 int old_size = c->local_size;
3132 void *local = calloc(1, t->function.local_size);
3133 struct value *fbody = var_value(c, v->var);
3134 struct binode *arg = cast(binode, b->right);
3135 struct binode *param = t->function.params;
3138 struct var *pv = cast(var, param->left);
3139 struct type *vtype = NULL;
3140 struct value val = interp_exec(c, arg->left, &vtype);
3142 c->local = local; c->local_size = t->function.local_size;
3143 lval = var_value(c, pv->var);
3144 c->local = oldlocal; c->local_size = old_size;
3145 memcpy(lval, &val, vtype->size);
3146 param = cast(binode, param->right);
3147 arg = cast(binode, arg->right);
3149 c->local = local; c->local_size = t->function.local_size;
3150 if (t->function.inline_result && dtype) {
3151 _interp_exec(c, fbody->function, NULL, NULL);
3152 memcpy(dest, local, dtype->size);
3153 rvtype = ret.type = NULL;
3155 rv = interp_exec(c, fbody->function, &rvtype);
3156 c->local = oldlocal; c->local_size = old_size;
3161 ## Complex executables: statements and expressions
3163 Now that we have types and values and variables and most of the basic
3164 Terms which provide access to these, we can explore the more complex
3165 code that combine all of these to get useful work done. Specifically
3166 statements and expressions.
3168 Expressions are various combinations of Terms. We will use operator
3169 precedence to ensure correct parsing. The simplest Expression is just a
3170 Term - others will follow.
3175 Expression -> Term ${ $0 = $<Term; }$
3176 ## expression grammar
3178 ### Expressions: Conditional
3180 Our first user of the `binode` will be conditional expressions, which
3181 is a bit odd as they actually have three components. That will be
3182 handled by having 2 binodes for each expression. The conditional
3183 expression is the lowest precedence operator which is why we define it
3184 first - to start the precedence list.
3186 Conditional expressions are of the form "value `if` condition `else`
3187 other_value". They associate to the right, so everything to the right
3188 of `else` is part of an else value, while only a higher-precedence to
3189 the left of `if` is the if values. Between `if` and `else` there is no
3190 room for ambiguity, so a full conditional expression is allowed in
3196 ###### declare terminals
3200 ###### expression grammar
3202 | Expression if Expression else Expression $$ifelse ${ {
3203 struct binode *b1 = new(binode);
3204 struct binode *b2 = new(binode);
3214 ###### print binode cases
3217 b2 = cast(binode, b->right);
3218 if (bracket) printf("(");
3219 print_exec(b2->left, -1, bracket);
3221 print_exec(b->left, -1, bracket);
3223 print_exec(b2->right, -1, bracket);
3224 if (bracket) printf(")");
3227 ###### propagate binode cases
3230 /* cond must be Tbool, others must match */
3231 struct binode *b2 = cast(binode, b->right);
3234 propagate_types(b->left, c, ok, Tbool, 0);
3235 t = propagate_types(b2->left, c, ok, type, Rnolabel);
3236 t2 = propagate_types(b2->right, c, ok, type ?: t, Rnolabel);
3240 ###### interp binode cases
3243 struct binode *b2 = cast(binode, b->right);
3244 left = interp_exec(c, b->left, <ype);
3246 rv = interp_exec(c, b2->left, &rvtype); // UNTESTED
3248 rv = interp_exec(c, b2->right, &rvtype);
3254 We take a brief detour, now that we have expressions, to describe lists
3255 of expressions. These will be needed for function parameters and
3256 possibly other situations. They seem generic enough to introduce here
3257 to be used elsewhere.
3259 And ExpressionList will use the `List` type of `binode`, building up at
3260 the end. And place where they are used will probably call
3261 `reorder_bilist()` to get a more normal first/next arrangement.
3263 ###### declare terminals
3266 `List` execs have no implicit semantics, so they are never propagated or
3267 interpreted. The can be printed as a comma separate list, which is how
3268 they are parsed. Note they are also used for function formal parameter
3269 lists. In that case a separate function is used to print them.
3271 ###### print binode cases
3275 print_exec(b->left, -1, bracket);
3278 b = cast(binode, b->right);
3282 ###### propagate binode cases
3283 case List: abort(); // NOTEST
3284 ###### interp binode cases
3285 case List: abort(); // NOTEST
3290 ExpressionList -> ExpressionList , Expression ${
3303 ### Expressions: Boolean
3305 The next class of expressions to use the `binode` will be Boolean
3306 expressions. "`and then`" and "`or else`" are similar to `and` and `or`
3307 have same corresponding precendence. The difference is that they don't
3308 evaluate the second expression if not necessary.
3317 ###### declare terminals
3322 ###### expression grammar
3323 | Expression or Expression ${ {
3324 struct binode *b = new(binode);
3330 | Expression or else Expression ${ {
3331 struct binode *b = new(binode);
3338 | Expression and Expression ${ {
3339 struct binode *b = new(binode);
3345 | Expression and then Expression ${ {
3346 struct binode *b = new(binode);
3353 | not Expression ${ {
3354 struct binode *b = new(binode);
3360 ###### print binode cases
3362 if (bracket) printf("(");
3363 print_exec(b->left, -1, bracket);
3365 print_exec(b->right, -1, bracket);
3366 if (bracket) printf(")");
3369 if (bracket) printf("(");
3370 print_exec(b->left, -1, bracket);
3371 printf(" and then ");
3372 print_exec(b->right, -1, bracket);
3373 if (bracket) printf(")");
3376 if (bracket) printf("(");
3377 print_exec(b->left, -1, bracket);
3379 print_exec(b->right, -1, bracket);
3380 if (bracket) printf(")");
3383 if (bracket) printf("(");
3384 print_exec(b->left, -1, bracket);
3385 printf(" or else ");
3386 print_exec(b->right, -1, bracket);
3387 if (bracket) printf(")");
3390 if (bracket) printf("(");
3392 print_exec(b->right, -1, bracket);
3393 if (bracket) printf(")");
3396 ###### propagate binode cases
3402 /* both must be Tbool, result is Tbool */
3403 propagate_types(b->left, c, ok, Tbool, 0);
3404 propagate_types(b->right, c, ok, Tbool, 0);
3405 if (type && type != Tbool)
3406 type_err(c, "error: %1 operation found where %2 expected", prog,
3410 ###### interp binode cases
3412 rv = interp_exec(c, b->left, &rvtype);
3413 right = interp_exec(c, b->right, &rtype);
3414 rv.bool = rv.bool && right.bool;
3417 rv = interp_exec(c, b->left, &rvtype);
3419 rv = interp_exec(c, b->right, NULL);
3422 rv = interp_exec(c, b->left, &rvtype);
3423 right = interp_exec(c, b->right, &rtype);
3424 rv.bool = rv.bool || right.bool;
3427 rv = interp_exec(c, b->left, &rvtype);
3429 rv = interp_exec(c, b->right, NULL);
3432 rv = interp_exec(c, b->right, &rvtype);
3436 ### Expressions: Comparison
3438 Of slightly higher precedence that Boolean expressions are Comparisons.
3439 A comparison takes arguments of any comparable type, but the two types
3442 To simplify the parsing we introduce an `eop` which can record an
3443 expression operator, and the `CMPop` non-terminal will match one of them.
3450 ###### ast functions
3451 static void free_eop(struct eop *e)
3465 ###### declare terminals
3466 $LEFT < > <= >= == != CMPop
3468 ###### expression grammar
3469 | Expression CMPop Expression ${ {
3470 struct binode *b = new(binode);
3480 CMPop -> < ${ $0.op = Less; }$
3481 | > ${ $0.op = Gtr; }$
3482 | <= ${ $0.op = LessEq; }$
3483 | >= ${ $0.op = GtrEq; }$
3484 | == ${ $0.op = Eql; }$
3485 | != ${ $0.op = NEql; }$
3487 ###### print binode cases
3495 if (bracket) printf("(");
3496 print_exec(b->left, -1, bracket);
3498 case Less: printf(" < "); break;
3499 case LessEq: printf(" <= "); break;
3500 case Gtr: printf(" > "); break;
3501 case GtrEq: printf(" >= "); break;
3502 case Eql: printf(" == "); break;
3503 case NEql: printf(" != "); break;
3504 default: abort(); // NOTEST
3506 print_exec(b->right, -1, bracket);
3507 if (bracket) printf(")");
3510 ###### propagate binode cases
3517 /* Both must match but not be labels, result is Tbool */
3518 t = propagate_types(b->left, c, ok, NULL, Rnolabel);
3520 propagate_types(b->right, c, ok, t, 0);
3522 t = propagate_types(b->right, c, ok, NULL, Rnolabel); // UNTESTED
3524 t = propagate_types(b->left, c, ok, t, 0); // UNTESTED
3526 if (!type_compat(type, Tbool, 0))
3527 type_err(c, "error: Comparison returns %1 but %2 expected", prog,
3528 Tbool, rules, type);
3531 ###### interp binode cases
3540 left = interp_exec(c, b->left, <ype);
3541 right = interp_exec(c, b->right, &rtype);
3542 cmp = value_cmp(ltype, rtype, &left, &right);
3545 case Less: rv.bool = cmp < 0; break;
3546 case LessEq: rv.bool = cmp <= 0; break;
3547 case Gtr: rv.bool = cmp > 0; break;
3548 case GtrEq: rv.bool = cmp >= 0; break;
3549 case Eql: rv.bool = cmp == 0; break;
3550 case NEql: rv.bool = cmp != 0; break;
3551 default: rv.bool = 0; break; // NOTEST
3556 ### Expressions: Arithmetic etc.
3558 The remaining expressions with the highest precedence are arithmetic,
3559 string concatenation, and string conversion. String concatenation
3560 (`++`) has the same precedence as multiplication and division, but lower
3563 String conversion is a temporary feature until I get a better type
3564 system. `$` is a prefix operator which expects a string and returns
3567 `+` and `-` are both infix and prefix operations (where they are
3568 absolute value and negation). These have different operator names.
3570 We also have a 'Bracket' operator which records where parentheses were
3571 found. This makes it easy to reproduce these when printing. Possibly I
3572 should only insert brackets were needed for precedence. Putting
3573 parentheses around an expression converts it into a Term,
3583 ###### declare terminals
3589 ###### expression grammar
3590 | Expression Eop Expression ${ {
3591 struct binode *b = new(binode);
3598 | Expression Top Expression ${ {
3599 struct binode *b = new(binode);
3606 | Uop Expression ${ {
3607 struct binode *b = new(binode);
3615 | ( Expression ) ${ {
3616 struct binode *b = new_pos(binode, $1);
3625 Eop -> + ${ $0.op = Plus; }$
3626 | - ${ $0.op = Minus; }$
3628 Uop -> + ${ $0.op = Absolute; }$
3629 | - ${ $0.op = Negate; }$
3630 | $ ${ $0.op = StringConv; }$
3632 Top -> * ${ $0.op = Times; }$
3633 | / ${ $0.op = Divide; }$
3634 | % ${ $0.op = Rem; }$
3635 | ++ ${ $0.op = Concat; }$
3637 ###### print binode cases
3644 if (bracket) printf("(");
3645 print_exec(b->left, indent, bracket);
3647 case Plus: fputs(" + ", stdout); break;
3648 case Minus: fputs(" - ", stdout); break;
3649 case Times: fputs(" * ", stdout); break;
3650 case Divide: fputs(" / ", stdout); break;
3651 case Rem: fputs(" % ", stdout); break;
3652 case Concat: fputs(" ++ ", stdout); break;
3653 default: abort(); // NOTEST
3655 print_exec(b->right, indent, bracket);
3656 if (bracket) printf(")");
3661 if (bracket) printf("(");
3663 case Absolute: fputs("+", stdout); break;
3664 case Negate: fputs("-", stdout); break;
3665 case StringConv: fputs("$", stdout); break;
3666 default: abort(); // NOTEST
3668 print_exec(b->right, indent, bracket);
3669 if (bracket) printf(")");
3673 print_exec(b->right, indent, bracket);
3677 ###### propagate binode cases
3683 /* both must be numbers, result is Tnum */
3686 /* as propagate_types ignores a NULL,
3687 * unary ops fit here too */
3688 propagate_types(b->left, c, ok, Tnum, 0);
3689 propagate_types(b->right, c, ok, Tnum, 0);
3690 if (!type_compat(type, Tnum, 0))
3691 type_err(c, "error: Arithmetic returns %1 but %2 expected", prog,
3696 /* both must be Tstr, result is Tstr */
3697 propagate_types(b->left, c, ok, Tstr, 0);
3698 propagate_types(b->right, c, ok, Tstr, 0);
3699 if (!type_compat(type, Tstr, 0))
3700 type_err(c, "error: Concat returns %1 but %2 expected", prog,
3705 /* op must be string, result is number */
3706 propagate_types(b->left, c, ok, Tstr, 0);
3707 if (!type_compat(type, Tnum, 0))
3708 type_err(c, // UNTESTED
3709 "error: Can only convert string to number, not %1",
3710 prog, type, 0, NULL);
3714 return propagate_types(b->right, c, ok, type, 0);
3716 ###### interp binode cases
3719 rv = interp_exec(c, b->left, &rvtype);
3720 right = interp_exec(c, b->right, &rtype);
3721 mpq_add(rv.num, rv.num, right.num);
3724 rv = interp_exec(c, b->left, &rvtype);
3725 right = interp_exec(c, b->right, &rtype);
3726 mpq_sub(rv.num, rv.num, right.num);
3729 rv = interp_exec(c, b->left, &rvtype);
3730 right = interp_exec(c, b->right, &rtype);
3731 mpq_mul(rv.num, rv.num, right.num);
3734 rv = interp_exec(c, b->left, &rvtype);
3735 right = interp_exec(c, b->right, &rtype);
3736 mpq_div(rv.num, rv.num, right.num);
3741 left = interp_exec(c, b->left, <ype);
3742 right = interp_exec(c, b->right, &rtype);
3743 mpz_init(l); mpz_init(r); mpz_init(rem);
3744 mpz_tdiv_q(l, mpq_numref(left.num), mpq_denref(left.num));
3745 mpz_tdiv_q(r, mpq_numref(right.num), mpq_denref(right.num));
3746 mpz_tdiv_r(rem, l, r);
3747 val_init(Tnum, &rv);
3748 mpq_set_z(rv.num, rem);
3749 mpz_clear(r); mpz_clear(l); mpz_clear(rem);
3754 rv = interp_exec(c, b->right, &rvtype);
3755 mpq_neg(rv.num, rv.num);
3758 rv = interp_exec(c, b->right, &rvtype);
3759 mpq_abs(rv.num, rv.num);
3762 rv = interp_exec(c, b->right, &rvtype);
3765 left = interp_exec(c, b->left, <ype);
3766 right = interp_exec(c, b->right, &rtype);
3768 rv.str = text_join(left.str, right.str);
3771 right = interp_exec(c, b->right, &rvtype);
3775 struct text tx = right.str;
3778 if (tx.txt[0] == '-') {
3779 neg = 1; // UNTESTED
3780 tx.txt++; // UNTESTED
3781 tx.len--; // UNTESTED
3783 if (number_parse(rv.num, tail, tx) == 0)
3784 mpq_init(rv.num); // UNTESTED
3786 mpq_neg(rv.num, rv.num); // UNTESTED
3788 printf("Unsupported suffix: %.*s\n", tx.len, tx.txt); // UNTESTED
3792 ###### value functions
3794 static struct text text_join(struct text a, struct text b)
3797 rv.len = a.len + b.len;
3798 rv.txt = malloc(rv.len);
3799 memcpy(rv.txt, a.txt, a.len);
3800 memcpy(rv.txt+a.len, b.txt, b.len);
3804 ### Blocks, Statements, and Statement lists.
3806 Now that we have expressions out of the way we need to turn to
3807 statements. There are simple statements and more complex statements.
3808 Simple statements do not contain (syntactic) newlines, complex statements do.
3810 Statements often come in sequences and we have corresponding simple
3811 statement lists and complex statement lists.
3812 The former comprise only simple statements separated by semicolons.
3813 The later comprise complex statements and simple statement lists. They are
3814 separated by newlines. Thus the semicolon is only used to separate
3815 simple statements on the one line. This may be overly restrictive,
3816 but I'm not sure I ever want a complex statement to share a line with
3819 Note that a simple statement list can still use multiple lines if
3820 subsequent lines are indented, so
3822 ###### Example: wrapped simple statement list
3827 is a single simple statement list. This might allow room for
3828 confusion, so I'm not set on it yet.
3830 A simple statement list needs no extra syntax. A complex statement
3831 list has two syntactic forms. It can be enclosed in braces (much like
3832 C blocks), or it can be introduced by an indent and continue until an
3833 unindented newline (much like Python blocks). With this extra syntax
3834 it is referred to as a block.
3836 Note that a block does not have to include any newlines if it only
3837 contains simple statements. So both of:
3839 if condition: a=b; d=f
3841 if condition { a=b; print f }
3845 In either case the list is constructed from a `binode` list with
3846 `Block` as the operator. When parsing the list it is most convenient
3847 to append to the end, so a list is a list and a statement. When using
3848 the list it is more convenient to consider a list to be a statement
3849 and a list. So we need a function to re-order a list.
3850 `reorder_bilist` serves this purpose.
3852 The only stand-alone statement we introduce at this stage is `pass`
3853 which does nothing and is represented as a `NULL` pointer in a `Block`
3854 list. Other stand-alone statements will follow once the infrastructure
3857 As many statements will use binodes, we declare a binode pointer 'b' in
3858 the common header for all reductions to use.
3860 ###### Parser: reduce
3871 Block -> { IN OptNL Statementlist OUT OptNL } ${ $0 = $<Sl; }$
3872 | { SimpleStatements } ${ $0 = reorder_bilist($<SS); }$
3873 | SimpleStatements ; ${ $0 = reorder_bilist($<SS); }$
3874 | SimpleStatements EOL ${ $0 = reorder_bilist($<SS); }$
3875 | IN OptNL Statementlist OUT ${ $0 = $<Sl; }$
3877 OpenBlock -> OpenScope { IN OptNL Statementlist OUT OptNL } ${ $0 = $<Sl; }$
3878 | OpenScope { SimpleStatements } ${ $0 = reorder_bilist($<SS); }$
3879 | OpenScope SimpleStatements ; ${ $0 = reorder_bilist($<SS); }$
3880 | OpenScope SimpleStatements EOL ${ $0 = reorder_bilist($<SS); }$
3881 | IN OpenScope OptNL Statementlist OUT ${ $0 = $<Sl; }$
3883 UseBlock -> { OpenScope IN OptNL Statementlist OUT OptNL } ${ $0 = $<Sl; }$
3884 | { OpenScope SimpleStatements } ${ $0 = reorder_bilist($<SS); }$
3885 | IN OpenScope OptNL Statementlist OUT ${ $0 = $<Sl; }$
3887 ColonBlock -> { IN OptNL Statementlist OUT OptNL } ${ $0 = $<Sl; }$
3888 | { SimpleStatements } ${ $0 = reorder_bilist($<SS); }$
3889 | : SimpleStatements ; ${ $0 = reorder_bilist($<SS); }$
3890 | : SimpleStatements EOL ${ $0 = reorder_bilist($<SS); }$
3891 | : IN OptNL Statementlist OUT ${ $0 = $<Sl; }$
3893 Statementlist -> ComplexStatements ${ $0 = reorder_bilist($<CS); }$
3895 ComplexStatements -> ComplexStatements ComplexStatement ${
3905 | ComplexStatement ${
3917 ComplexStatement -> SimpleStatements Newlines ${
3918 $0 = reorder_bilist($<SS);
3920 | SimpleStatements ; Newlines ${
3921 $0 = reorder_bilist($<SS);
3923 ## ComplexStatement Grammar
3926 SimpleStatements -> SimpleStatements ; SimpleStatement ${
3932 | SimpleStatement ${
3941 SimpleStatement -> pass ${ $0 = NULL; }$
3942 | ERROR ${ tok_err(c, "Syntax error in statement", &$1); }$
3943 ## SimpleStatement Grammar
3945 ###### print binode cases
3949 if (b->left == NULL) // UNTESTED
3950 printf("pass"); // UNTESTED
3952 print_exec(b->left, indent, bracket); // UNTESTED
3953 if (b->right) { // UNTESTED
3954 printf("; "); // UNTESTED
3955 print_exec(b->right, indent, bracket); // UNTESTED
3958 // block, one per line
3959 if (b->left == NULL)
3960 do_indent(indent, "pass\n");
3962 print_exec(b->left, indent, bracket);
3964 print_exec(b->right, indent, bracket);
3968 ###### propagate binode cases
3971 /* If any statement returns something other than Tnone
3972 * or Tbool then all such must return same type.
3973 * As each statement may be Tnone or something else,
3974 * we must always pass NULL (unknown) down, otherwise an incorrect
3975 * error might occur. We never return Tnone unless it is
3980 for (e = b; e; e = cast(binode, e->right)) {
3981 t = propagate_types(e->left, c, ok, NULL, rules);
3982 if ((rules & Rboolok) && (t == Tbool || t == Tnone))
3984 if (t == Tnone && e->right)
3985 /* Only the final statement *must* return a value
3993 type_err(c, "error: expected %1%r, found %2",
3994 e->left, type, rules, t);
4000 ###### interp binode cases
4002 while (rvtype == Tnone &&
4005 rv = interp_exec(c, b->left, &rvtype);
4006 b = cast(binode, b->right);
4010 ### The Print statement
4012 `print` is a simple statement that takes a comma-separated list of
4013 expressions and prints the values separated by spaces and terminated
4014 by a newline. No control of formatting is possible.
4016 `print` uses `ExpressionList` to collect the expressions and stores them
4017 on the left side of a `Print` binode unlessthere is a trailing comma
4018 when the list is stored on the `right` side and no trailing newline is
4024 ##### declare terminals
4027 ###### SimpleStatement Grammar
4029 | print ExpressionList ${
4030 $0 = b = new(binode);
4033 b->left = reorder_bilist($<EL);
4035 | print ExpressionList , ${ {
4036 $0 = b = new(binode);
4038 b->right = reorder_bilist($<EL);
4042 $0 = b = new(binode);
4048 ###### print binode cases
4051 do_indent(indent, "print");
4053 print_exec(b->right, -1, bracket);
4056 print_exec(b->left, -1, bracket);
4061 ###### propagate binode cases
4064 /* don't care but all must be consistent */
4066 b = cast(binode, b->left);
4068 b = cast(binode, b->right);
4070 propagate_types(b->left, c, ok, NULL, Rnolabel);
4071 b = cast(binode, b->right);
4075 ###### interp binode cases
4079 struct binode *b2 = cast(binode, b->left);
4081 b2 = cast(binode, b->right);
4082 for (; b2; b2 = cast(binode, b2->right)) {
4083 left = interp_exec(c, b2->left, <ype);
4084 print_value(ltype, &left, stdout);
4085 free_value(ltype, &left);
4089 if (b->right == NULL)
4095 ###### Assignment statement
4097 An assignment will assign a value to a variable, providing it hasn't
4098 been declared as a constant. The analysis phase ensures that the type
4099 will be correct so the interpreter just needs to perform the
4100 calculation. There is a form of assignment which declares a new
4101 variable as well as assigning a value. If a name is assigned before
4102 it is declared, and error will be raised as the name is created as
4103 `Tlabel` and it is illegal to assign to such names.
4109 ###### declare terminals
4112 ###### SimpleStatement Grammar
4113 | Term = Expression ${
4114 $0 = b= new(binode);
4119 | VariableDecl = Expression ${
4120 $0 = b= new(binode);
4127 if ($1->var->where_set == NULL) {
4129 "Variable declared with no type or value: %v",
4133 $0 = b = new(binode);
4140 ###### print binode cases
4143 do_indent(indent, "");
4144 print_exec(b->left, indent, bracket);
4146 print_exec(b->right, indent, bracket);
4153 struct variable *v = cast(var, b->left)->var;
4154 do_indent(indent, "");
4155 print_exec(b->left, indent, bracket);
4156 if (cast(var, b->left)->var->constant) {
4158 if (v->explicit_type) {
4159 type_print(v->type, stdout);
4164 if (v->explicit_type) {
4165 type_print(v->type, stdout);
4171 print_exec(b->right, indent, bracket);
4178 ###### propagate binode cases
4182 /* Both must match and not be labels,
4183 * Type must support 'dup',
4184 * For Assign, left must not be constant.
4187 t = propagate_types(b->left, c, ok, NULL,
4188 Rnolabel | (b->op == Assign ? Rnoconstant : 0));
4193 if (propagate_types(b->right, c, ok, t, 0) != t)
4194 if (b->left->type == Xvar)
4195 type_err(c, "info: variable '%v' was set as %1 here.",
4196 cast(var, b->left)->var->where_set, t, rules, NULL);
4198 t = propagate_types(b->right, c, ok, NULL, Rnolabel);
4200 propagate_types(b->left, c, ok, t,
4201 (b->op == Assign ? Rnoconstant : 0));
4203 if (t && t->dup == NULL && t->name.txt[0] != ' ') // HACK
4204 type_err(c, "error: cannot assign value of type %1", b, t, 0, NULL);
4209 ###### interp binode cases
4212 lleft = linterp_exec(c, b->left, <ype);
4214 dinterp_exec(c, b->right, lleft, ltype, 1);
4220 struct variable *v = cast(var, b->left)->var;
4223 val = var_value(c, v);
4224 if (v->type->prepare_type)
4225 v->type->prepare_type(c, v->type, 0);
4227 dinterp_exec(c, b->right, val, v->type, 0);
4229 val_init(v->type, val);
4233 ### The `use` statement
4235 The `use` statement is the last "simple" statement. It is needed when a
4236 statement block can return a value. This includes the body of a
4237 function which has a return type, and the "condition" code blocks in
4238 `if`, `while`, and `switch` statements.
4243 ###### declare terminals
4246 ###### SimpleStatement Grammar
4248 $0 = b = new_pos(binode, $1);
4251 if (b->right->type == Xvar) {
4252 struct var *v = cast(var, b->right);
4253 if (v->var->type == Tnone) {
4254 /* Convert this to a label */
4257 v->var->type = Tlabel;
4258 val = global_alloc(c, Tlabel, v->var, NULL);
4264 ###### print binode cases
4267 do_indent(indent, "use ");
4268 print_exec(b->right, -1, bracket);
4273 ###### propagate binode cases
4276 /* result matches value */
4277 return propagate_types(b->right, c, ok, type, 0);
4279 ###### interp binode cases
4282 rv = interp_exec(c, b->right, &rvtype);
4285 ### The Conditional Statement
4287 This is the biggy and currently the only complex statement. This
4288 subsumes `if`, `while`, `do/while`, `switch`, and some parts of `for`.
4289 It is comprised of a number of parts, all of which are optional though
4290 set combinations apply. Each part is (usually) a key word (`then` is
4291 sometimes optional) followed by either an expression or a code block,
4292 except the `casepart` which is a "key word and an expression" followed
4293 by a code block. The code-block option is valid for all parts and,
4294 where an expression is also allowed, the code block can use the `use`
4295 statement to report a value. If the code block does not report a value
4296 the effect is similar to reporting `True`.
4298 The `else` and `case` parts, as well as `then` when combined with
4299 `if`, can contain a `use` statement which will apply to some
4300 containing conditional statement. `for` parts, `do` parts and `then`
4301 parts used with `for` can never contain a `use`, except in some
4302 subordinate conditional statement.
4304 If there is a `forpart`, it is executed first, only once.
4305 If there is a `dopart`, then it is executed repeatedly providing
4306 always that the `condpart` or `cond`, if present, does not return a non-True
4307 value. `condpart` can fail to return any value if it simply executes
4308 to completion. This is treated the same as returning `True`.
4310 If there is a `thenpart` it will be executed whenever the `condpart`
4311 or `cond` returns True (or does not return any value), but this will happen
4312 *after* `dopart` (when present).
4314 If `elsepart` is present it will be executed at most once when the
4315 condition returns `False` or some value that isn't `True` and isn't
4316 matched by any `casepart`. If there are any `casepart`s, they will be
4317 executed when the condition returns a matching value.
4319 The particular sorts of values allowed in case parts has not yet been
4320 determined in the language design, so nothing is prohibited.
4322 The various blocks in this complex statement potentially provide scope
4323 for variables as described earlier. Each such block must include the
4324 "OpenScope" nonterminal before parsing the block, and must call
4325 `var_block_close()` when closing the block.
4327 The code following "`if`", "`switch`" and "`for`" does not get its own
4328 scope, but is in a scope covering the whole statement, so names
4329 declared there cannot be redeclared elsewhere. Similarly the
4330 condition following "`while`" is in a scope the covers the body
4331 ("`do`" part) of the loop, and which does not allow conditional scope
4332 extension. Code following "`then`" (both looping and non-looping),
4333 "`else`" and "`case`" each get their own local scope.
4335 The type requirements on the code block in a `whilepart` are quite
4336 unusal. It is allowed to return a value of some identifiable type, in
4337 which case the loop aborts and an appropriate `casepart` is run, or it
4338 can return a Boolean, in which case the loop either continues to the
4339 `dopart` (on `True`) or aborts and runs the `elsepart` (on `False`).
4340 This is different both from the `ifpart` code block which is expected to
4341 return a Boolean, or the `switchpart` code block which is expected to
4342 return the same type as the casepart values. The correct analysis of
4343 the type of the `whilepart` code block is the reason for the
4344 `Rboolok` flag which is passed to `propagate_types()`.
4346 The `cond_statement` cannot fit into a `binode` so a new `exec` is
4347 defined. As there are two scopes which cover multiple parts - one for
4348 the whole statement and one for "while" and "do" - and as we will use
4349 the 'struct exec' to track scopes, we actually need two new types of
4350 exec. One is a `binode` for the looping part, the rest is the
4351 `cond_statement`. The `cond_statement` will use an auxilliary `struct
4352 casepart` to track a list of case parts.
4363 struct exec *action;
4364 struct casepart *next;
4366 struct cond_statement {
4368 struct exec *forpart, *condpart, *thenpart, *elsepart;
4369 struct binode *looppart;
4370 struct casepart *casepart;
4373 ###### ast functions
4375 static void free_casepart(struct casepart *cp)
4379 free_exec(cp->value);
4380 free_exec(cp->action);
4387 static void free_cond_statement(struct cond_statement *s)
4391 free_exec(s->forpart);
4392 free_exec(s->condpart);
4393 free_exec(s->looppart);
4394 free_exec(s->thenpart);
4395 free_exec(s->elsepart);
4396 free_casepart(s->casepart);
4400 ###### free exec cases
4401 case Xcond_statement: free_cond_statement(cast(cond_statement, e)); break;
4403 ###### ComplexStatement Grammar
4404 | CondStatement ${ $0 = $<1; }$
4406 ###### declare terminals
4407 $TERM for then while do
4414 // A CondStatement must end with EOL, as does CondSuffix and
4416 // ForPart, ThenPart, SwitchPart, CasePart are non-empty and
4417 // may or may not end with EOL
4418 // WhilePart and IfPart include an appropriate Suffix
4420 // ForPart, SwitchPart, and IfPart open scopes, o we have to close
4421 // them. WhilePart opens and closes its own scope.
4422 CondStatement -> ForPart OptNL ThenPart OptNL WhilePart CondSuffix ${
4425 $0->thenpart = $<TP;
4426 $0->looppart = $<WP;
4427 var_block_close(c, CloseSequential, $0);
4429 | ForPart OptNL WhilePart CondSuffix ${
4432 $0->looppart = $<WP;
4433 var_block_close(c, CloseSequential, $0);
4435 | WhilePart CondSuffix ${
4437 $0->looppart = $<WP;
4439 | SwitchPart OptNL CasePart CondSuffix ${
4441 $0->condpart = $<SP;
4442 $CP->next = $0->casepart;
4443 $0->casepart = $<CP;
4444 var_block_close(c, CloseSequential, $0);
4446 | SwitchPart : IN OptNL CasePart CondSuffix OUT Newlines ${
4448 $0->condpart = $<SP;
4449 $CP->next = $0->casepart;
4450 $0->casepart = $<CP;
4451 var_block_close(c, CloseSequential, $0);
4453 | IfPart IfSuffix ${
4455 $0->condpart = $IP.condpart; $IP.condpart = NULL;
4456 $0->thenpart = $IP.thenpart; $IP.thenpart = NULL;
4457 // This is where we close an "if" statement
4458 var_block_close(c, CloseSequential, $0);
4461 CondSuffix -> IfSuffix ${
4464 | Newlines CasePart CondSuffix ${
4466 $CP->next = $0->casepart;
4467 $0->casepart = $<CP;
4469 | CasePart CondSuffix ${
4471 $CP->next = $0->casepart;
4472 $0->casepart = $<CP;
4475 IfSuffix -> Newlines ${ $0 = new(cond_statement); }$
4476 | Newlines ElsePart ${ $0 = $<EP; }$
4477 | ElsePart ${$0 = $<EP; }$
4479 ElsePart -> else OpenBlock Newlines ${
4480 $0 = new(cond_statement);
4481 $0->elsepart = $<OB;
4482 var_block_close(c, CloseElse, $0->elsepart);
4484 | else OpenScope CondStatement ${
4485 $0 = new(cond_statement);
4486 $0->elsepart = $<CS;
4487 var_block_close(c, CloseElse, $0->elsepart);
4491 CasePart -> case Expression OpenScope ColonBlock ${
4492 $0 = calloc(1,sizeof(struct casepart));
4495 var_block_close(c, CloseParallel, $0->action);
4499 // These scopes are closed in CondStatement
4500 ForPart -> for OpenBlock ${
4504 ThenPart -> then OpenBlock ${
4506 var_block_close(c, CloseSequential, $0);
4510 // This scope is closed in CondStatement
4511 WhilePart -> while UseBlock OptNL do OpenBlock ${
4516 var_block_close(c, CloseSequential, $0->right);
4517 var_block_close(c, CloseSequential, $0);
4519 | while OpenScope Expression OpenScope ColonBlock ${
4524 var_block_close(c, CloseSequential, $0->right);
4525 var_block_close(c, CloseSequential, $0);
4529 IfPart -> if UseBlock OptNL then OpenBlock ${
4532 var_block_close(c, CloseParallel, $0.thenpart);
4534 | if OpenScope Expression OpenScope ColonBlock ${
4537 var_block_close(c, CloseParallel, $0.thenpart);
4539 | if OpenScope Expression OpenScope OptNL then Block ${
4542 var_block_close(c, CloseParallel, $0.thenpart);
4546 // This scope is closed in CondStatement
4547 SwitchPart -> switch OpenScope Expression ${
4550 | switch UseBlock ${
4554 ###### print binode cases
4556 if (b->left && b->left->type == Xbinode &&
4557 cast(binode, b->left)->op == Block) {
4559 do_indent(indent, "while {\n");
4561 do_indent(indent, "while\n");
4562 print_exec(b->left, indent+1, bracket);
4564 do_indent(indent, "} do {\n");
4566 do_indent(indent, "do\n");
4567 print_exec(b->right, indent+1, bracket);
4569 do_indent(indent, "}\n");
4571 do_indent(indent, "while ");
4572 print_exec(b->left, 0, bracket);
4577 print_exec(b->right, indent+1, bracket);
4579 do_indent(indent, "}\n");
4583 ###### print exec cases
4585 case Xcond_statement:
4587 struct cond_statement *cs = cast(cond_statement, e);
4588 struct casepart *cp;
4590 do_indent(indent, "for");
4591 if (bracket) printf(" {\n"); else printf("\n");
4592 print_exec(cs->forpart, indent+1, bracket);
4595 do_indent(indent, "} then {\n");
4597 do_indent(indent, "then\n");
4598 print_exec(cs->thenpart, indent+1, bracket);
4600 if (bracket) do_indent(indent, "}\n");
4603 print_exec(cs->looppart, indent, bracket);
4607 do_indent(indent, "switch");
4609 do_indent(indent, "if");
4610 if (cs->condpart && cs->condpart->type == Xbinode &&
4611 cast(binode, cs->condpart)->op == Block) {
4616 print_exec(cs->condpart, indent+1, bracket);
4618 do_indent(indent, "}\n");
4620 do_indent(indent, "then\n");
4621 print_exec(cs->thenpart, indent+1, bracket);
4625 print_exec(cs->condpart, 0, bracket);
4631 print_exec(cs->thenpart, indent+1, bracket);
4633 do_indent(indent, "}\n");
4638 for (cp = cs->casepart; cp; cp = cp->next) {
4639 do_indent(indent, "case ");
4640 print_exec(cp->value, -1, 0);
4645 print_exec(cp->action, indent+1, bracket);
4647 do_indent(indent, "}\n");
4650 do_indent(indent, "else");
4655 print_exec(cs->elsepart, indent+1, bracket);
4657 do_indent(indent, "}\n");
4662 ###### propagate binode cases
4664 t = propagate_types(b->right, c, ok, Tnone, 0);
4665 if (!type_compat(Tnone, t, 0))
4666 *ok = 0; // UNTESTED
4667 return propagate_types(b->left, c, ok, type, rules);
4669 ###### propagate exec cases
4670 case Xcond_statement:
4672 // forpart and looppart->right must return Tnone
4673 // thenpart must return Tnone if there is a loopart,
4674 // otherwise it is like elsepart.
4676 // be bool if there is no casepart
4677 // match casepart->values if there is a switchpart
4678 // either be bool or match casepart->value if there
4680 // elsepart and casepart->action must match the return type
4681 // expected of this statement.
4682 struct cond_statement *cs = cast(cond_statement, prog);
4683 struct casepart *cp;
4685 t = propagate_types(cs->forpart, c, ok, Tnone, 0);
4686 if (!type_compat(Tnone, t, 0))
4687 *ok = 0; // UNTESTED
4690 t = propagate_types(cs->thenpart, c, ok, Tnone, 0);
4691 if (!type_compat(Tnone, t, 0))
4692 *ok = 0; // UNTESTED
4694 if (cs->casepart == NULL) {
4695 propagate_types(cs->condpart, c, ok, Tbool, 0);
4696 propagate_types(cs->looppart, c, ok, Tbool, 0);
4698 /* Condpart must match case values, with bool permitted */
4700 for (cp = cs->casepart;
4701 cp && !t; cp = cp->next)
4702 t = propagate_types(cp->value, c, ok, NULL, 0);
4703 if (!t && cs->condpart)
4704 t = propagate_types(cs->condpart, c, ok, NULL, Rboolok); // UNTESTED
4705 if (!t && cs->looppart)
4706 t = propagate_types(cs->looppart, c, ok, NULL, Rboolok); // UNTESTED
4707 // Now we have a type (I hope) push it down
4709 for (cp = cs->casepart; cp; cp = cp->next)
4710 propagate_types(cp->value, c, ok, t, 0);
4711 propagate_types(cs->condpart, c, ok, t, Rboolok);
4712 propagate_types(cs->looppart, c, ok, t, Rboolok);
4715 // (if)then, else, and case parts must return expected type.
4716 if (!cs->looppart && !type)
4717 type = propagate_types(cs->thenpart, c, ok, NULL, rules);
4719 type = propagate_types(cs->elsepart, c, ok, NULL, rules);
4720 for (cp = cs->casepart;
4722 cp = cp->next) // UNTESTED
4723 type = propagate_types(cp->action, c, ok, NULL, rules); // UNTESTED
4726 propagate_types(cs->thenpart, c, ok, type, rules);
4727 propagate_types(cs->elsepart, c, ok, type, rules);
4728 for (cp = cs->casepart; cp ; cp = cp->next)
4729 propagate_types(cp->action, c, ok, type, rules);
4735 ###### interp binode cases
4737 // This just performs one iterration of the loop
4738 rv = interp_exec(c, b->left, &rvtype);
4739 if (rvtype == Tnone ||
4740 (rvtype == Tbool && rv.bool != 0))
4741 // rvtype is Tnone or Tbool, doesn't need to be freed
4742 interp_exec(c, b->right, NULL);
4745 ###### interp exec cases
4746 case Xcond_statement:
4748 struct value v, cnd;
4749 struct type *vtype, *cndtype;
4750 struct casepart *cp;
4751 struct cond_statement *cs = cast(cond_statement, e);
4754 interp_exec(c, cs->forpart, NULL);
4756 while ((cnd = interp_exec(c, cs->looppart, &cndtype)),
4757 cndtype == Tnone || (cndtype == Tbool && cnd.bool != 0))
4758 interp_exec(c, cs->thenpart, NULL);
4760 cnd = interp_exec(c, cs->condpart, &cndtype);
4761 if ((cndtype == Tnone ||
4762 (cndtype == Tbool && cnd.bool != 0))) {
4763 // cnd is Tnone or Tbool, doesn't need to be freed
4764 rv = interp_exec(c, cs->thenpart, &rvtype);
4765 // skip else (and cases)
4769 for (cp = cs->casepart; cp; cp = cp->next) {
4770 v = interp_exec(c, cp->value, &vtype);
4771 if (value_cmp(cndtype, vtype, &v, &cnd) == 0) {
4772 free_value(vtype, &v);
4773 free_value(cndtype, &cnd);
4774 rv = interp_exec(c, cp->action, &rvtype);
4777 free_value(vtype, &v);
4779 free_value(cndtype, &cnd);
4781 rv = interp_exec(c, cs->elsepart, &rvtype);
4788 ### Top level structure
4790 All the language elements so far can be used in various places. Now
4791 it is time to clarify what those places are.
4793 At the top level of a file there will be a number of declarations.
4794 Many of the things that can be declared haven't been described yet,
4795 such as functions, procedures, imports, and probably more.
4796 For now there are two sorts of things that can appear at the top
4797 level. They are predefined constants, `struct` types, and the `main`
4798 function. While the syntax will allow the `main` function to appear
4799 multiple times, that will trigger an error if it is actually attempted.
4801 The various declarations do not return anything. They store the
4802 various declarations in the parse context.
4804 ###### Parser: grammar
4807 Ocean -> OptNL DeclarationList
4809 ## declare terminals
4816 DeclarationList -> Declaration
4817 | DeclarationList Declaration
4819 Declaration -> ERROR Newlines ${
4820 tok_err(c, // UNTESTED
4821 "error: unhandled parse error", &$1);
4827 ## top level grammar
4831 ### The `const` section
4833 As well as being defined in with the code that uses them, constants
4834 can be declared at the top level. These have full-file scope, so they
4835 are always `InScope`. The value of a top level constant can be given
4836 as an expression, and this is evaluated immediately rather than in the
4837 later interpretation stage. Once we add functions to the language, we
4838 will need rules concern which, if any, can be used to define a top
4841 Constants are defined in a section that starts with the reserved word
4842 `const` and then has a block with a list of assignment statements.
4843 For syntactic consistency, these must use the double-colon syntax to
4844 make it clear that they are constants. Type can also be given: if
4845 not, the type will be determined during analysis, as with other
4848 As the types constants are inserted at the head of a list, printing
4849 them in the same order that they were read is not straight forward.
4850 We take a quadratic approach here and count the number of constants
4851 (variables of depth 0), then count down from there, each time
4852 searching through for the Nth constant for decreasing N.
4854 ###### top level grammar
4858 DeclareConstant -> const { IN OptNL ConstList OUT OptNL } Newlines
4859 | const { SimpleConstList } Newlines
4860 | const IN OptNL ConstList OUT Newlines
4861 | const SimpleConstList Newlines
4863 ConstList -> ConstList SimpleConstLine
4865 SimpleConstList -> SimpleConstList ; Const
4868 SimpleConstLine -> SimpleConstList Newlines
4869 | ERROR Newlines ${ tok_err(c, "Syntax error in constant", &$1); }$
4872 CType -> Type ${ $0 = $<1; }$
4875 Const -> IDENTIFIER :: CType = Expression ${ {
4879 v = var_decl(c, $1.txt);
4881 struct var *var = new_pos(var, $1);
4882 v->where_decl = var;
4888 struct variable *vorig = var_ref(c, $1.txt);
4889 tok_err(c, "error: name already declared", &$1);
4890 type_err(c, "info: this is where '%v' was first declared",
4891 vorig->where_decl, NULL, 0, NULL);
4895 propagate_types($5, c, &ok, $3, 0);
4900 struct value res = interp_exec(c, $5, &v->type);
4901 global_alloc(c, v->type, v, &res);
4905 ###### print const decls
4910 while (target != 0) {
4912 for (v = context.in_scope; v; v=v->in_scope)
4913 if (v->depth == 0 && v->constant) {
4924 struct value *val = var_value(&context, v);
4925 printf(" %.*s :: ", v->name->name.len, v->name->name.txt);
4926 type_print(v->type, stdout);
4928 if (v->type == Tstr)
4930 print_value(v->type, val, stdout);
4931 if (v->type == Tstr)
4939 ### Function declarations
4941 The code in an Ocean program is all stored in function declarations.
4942 One of the functions must be named `main` and it must accept an array of
4943 strings as a parameter - the command line arguments.
4945 As this is the top level, several things are handled a bit differently.
4946 The function is not interpreted by `interp_exec` as that isn't passed
4947 the argument list which the program requires. Similarly type analysis
4948 is a bit more interesting at this level.
4950 ###### ast functions
4952 static struct type *handle_results(struct parse_context *c,
4953 struct binode *results)
4955 /* Create a 'struct' type from the results list, which
4956 * is a list for 'struct var'
4958 struct type *t = add_anon_type(c, &structure_prototype,
4959 " function result");
4963 for (b = results; b; b = cast(binode, b->right))
4965 t->structure.nfields = cnt;
4966 t->structure.fields = calloc(cnt, sizeof(struct field));
4968 for (b = results; b; b = cast(binode, b->right)) {
4969 struct var *v = cast(var, b->left);
4970 struct field *f = &t->structure.fields[cnt++];
4971 int a = v->var->type->align;
4972 f->name = v->var->name->name;
4973 f->type = v->var->type;
4975 f->offset = t->size;
4976 v->var->frame_pos = f->offset;
4977 t->size += ((f->type->size - 1) | (a-1)) + 1;
4980 variable_unlink_exec(v->var);
4982 free_binode(results);
4986 static struct variable *declare_function(struct parse_context *c,
4987 struct variable *name,
4988 struct binode *args,
4990 struct binode *results,
4994 struct value fn = {.function = code};
4996 var_block_close(c, CloseFunction, code);
4997 t = add_anon_type(c, &function_prototype,
4998 "func %.*s", name->name->name.len,
4999 name->name->name.txt);
5001 t->function.params = reorder_bilist(args);
5003 ret = handle_results(c, reorder_bilist(results));
5004 t->function.inline_result = 1;
5005 t->function.local_size = ret->size;
5007 t->function.return_type = ret;
5008 global_alloc(c, t, name, &fn);
5009 name->type->function.scope = c->out_scope;
5014 var_block_close(c, CloseFunction, NULL);
5016 c->out_scope = NULL;
5020 ###### declare terminals
5023 ###### top level grammar
5026 DeclareFunction -> func FuncName ( OpenScope ArgsLine ) Block Newlines ${
5027 $0 = declare_function(c, $<FN, $<Ar, Tnone, NULL, $<Bl);
5029 | func FuncName IN OpenScope Args OUT OptNL do Block Newlines ${
5030 $0 = declare_function(c, $<FN, $<Ar, Tnone, NULL, $<Bl);
5032 | func FuncName NEWLINE OpenScope OptNL do Block Newlines ${
5033 $0 = declare_function(c, $<FN, NULL, Tnone, NULL, $<Bl);
5035 | func FuncName ( OpenScope ArgsLine ) : Type Block Newlines ${
5036 $0 = declare_function(c, $<FN, $<Ar, $<Ty, NULL, $<Bl);
5038 | func FuncName ( OpenScope ArgsLine ) : ( ArgsLine ) Block Newlines ${
5039 $0 = declare_function(c, $<FN, $<AL, NULL, $<AL2, $<Bl);
5041 | func FuncName IN OpenScope Args OUT OptNL return Type Newlines do Block Newlines ${
5042 $0 = declare_function(c, $<FN, $<Ar, $<Ty, NULL, $<Bl);
5044 | func FuncName NEWLINE OpenScope return Type Newlines do Block Newlines ${
5045 $0 = declare_function(c, $<FN, NULL, $<Ty, NULL, $<Bl);
5047 | func FuncName IN OpenScope Args OUT OptNL return IN Args OUT OptNL do Block Newlines ${
5048 $0 = declare_function(c, $<FN, $<Ar, NULL, $<Ar2, $<Bl);
5050 | func FuncName NEWLINE OpenScope return IN Args OUT OptNL do Block Newlines ${
5051 $0 = declare_function(c, $<FN, NULL, NULL, $<Ar, $<Bl);
5054 ###### print func decls
5059 while (target != 0) {
5061 for (v = context.in_scope; v; v=v->in_scope)
5062 if (v->depth == 0 && v->type && v->type->check_args) {
5071 struct value *val = var_value(&context, v);
5072 printf("func %.*s", v->name->name.len, v->name->name.txt);
5073 v->type->print_type_decl(v->type, stdout);
5075 print_exec(val->function, 0, brackets);
5077 print_value(v->type, val, stdout);
5078 printf("/* frame size %d */\n", v->type->function.local_size);
5084 ###### core functions
5086 static int analyse_funcs(struct parse_context *c)
5090 for (v = c->in_scope; v; v = v->in_scope) {
5094 if (v->depth != 0 || !v->type || !v->type->check_args)
5096 ret = v->type->function.inline_result ?
5097 Tnone : v->type->function.return_type;
5098 val = var_value(c, v);
5101 propagate_types(val->function, c, &ok, ret, 0);
5104 /* Make sure everything is still consistent */
5105 propagate_types(val->function, c, &ok, ret, 0);
5108 if (!v->type->function.inline_result &&
5109 !v->type->function.return_type->dup) {
5110 type_err(c, "error: function cannot return value of type %1",
5111 v->where_decl, v->type->function.return_type, 0, NULL);
5114 scope_finalize(c, v->type);
5119 static int analyse_main(struct type *type, struct parse_context *c)
5121 struct binode *bp = type->function.params;
5125 struct type *argv_type;
5127 argv_type = add_anon_type(c, &array_prototype, "argv");
5128 argv_type->array.member = Tstr;
5129 argv_type->array.unspec = 1;
5131 for (b = bp; b; b = cast(binode, b->right)) {
5135 propagate_types(b->left, c, &ok, argv_type, 0);
5137 default: /* invalid */ // NOTEST
5138 propagate_types(b->left, c, &ok, Tnone, 0); // NOTEST
5144 return !c->parse_error;
5147 static void interp_main(struct parse_context *c, int argc, char **argv)
5149 struct value *progp = NULL;
5150 struct text main_name = { "main", 4 };
5151 struct variable *mainv;
5157 mainv = var_ref(c, main_name);
5159 progp = var_value(c, mainv);
5160 if (!progp || !progp->function) {
5161 fprintf(stderr, "oceani: no main function found.\n");
5165 if (!analyse_main(mainv->type, c)) {
5166 fprintf(stderr, "oceani: main has wrong type.\n");
5170 al = mainv->type->function.params;
5172 c->local_size = mainv->type->function.local_size;
5173 c->local = calloc(1, c->local_size);
5175 struct var *v = cast(var, al->left);
5176 struct value *vl = var_value(c, v->var);
5186 mpq_set_ui(argcq, argc, 1);
5187 memcpy(var_value(c, t->array.vsize), &argcq, sizeof(argcq));
5188 t->prepare_type(c, t, 0);
5189 array_init(v->var->type, vl);
5190 for (i = 0; i < argc; i++) {
5191 struct value *vl2 = vl->array + i * v->var->type->array.member->size;
5193 arg.str.txt = argv[i];
5194 arg.str.len = strlen(argv[i]);
5195 free_value(Tstr, vl2);
5196 dup_value(Tstr, &arg, vl2);
5200 al = cast(binode, al->right);
5202 v = interp_exec(c, progp->function, &vtype);
5203 free_value(vtype, &v);
5208 ###### ast functions
5209 void free_variable(struct variable *v)
5213 ## And now to test it out.
5215 Having a language requires having a "hello world" program. I'll
5216 provide a little more than that: a program that prints "Hello world"
5217 finds the GCD of two numbers, prints the first few elements of
5218 Fibonacci, performs a binary search for a number, and a few other
5219 things which will likely grow as the languages grows.
5221 ###### File: oceani.mk
5224 @echo "===== DEMO ====="
5225 ./oceani --section "demo: hello" oceani.mdc 55 33
5231 four ::= 2 + 2 ; five ::= 10/2
5232 const pie ::= "I like Pie";
5233 cake ::= "The cake is"
5241 func main(argv:[argc::]string)
5242 print "Hello World, what lovely oceans you have!"
5243 print "Are there", five, "?"
5244 print pi, pie, "but", cake
5246 A := $argv[1]; B := $argv[2]
5248 /* When a variable is defined in both branches of an 'if',
5249 * and used afterwards, the variables are merged.
5255 print "Is", A, "bigger than", B,"? ", bigger
5256 /* If a variable is not used after the 'if', no
5257 * merge happens, so types can be different
5260 double:string = "yes"
5261 print A, "is more than twice", B, "?", double
5264 print "double", B, "is", double
5269 if a > 0 and then b > 0:
5275 print "GCD of", A, "and", B,"is", a
5277 print a, "is not positive, cannot calculate GCD"
5279 print b, "is not positive, cannot calculate GCD"
5284 print "Fibonacci:", f1,f2,
5285 then togo = togo - 1
5293 /* Binary search... */
5298 mid := (lo + hi) / 2
5311 print "Yay, I found", target
5313 print "Closest I found was", lo
5318 // "middle square" PRNG. Not particularly good, but one my
5319 // Dad taught me - the first one I ever heard of.
5320 for i:=1; then i = i + 1; while i < size:
5321 n := list[i-1] * list[i-1]
5322 list[i] = (n / 100) % 10 000
5324 print "Before sort:",
5325 for i:=0; then i = i + 1; while i < size:
5329 for i := 1; then i=i+1; while i < size:
5330 for j:=i-1; then j=j-1; while j >= 0:
5331 if list[j] > list[j+1]:
5335 print " After sort:",
5336 for i:=0; then i = i + 1; while i < size:
5340 if 1 == 2 then print "yes"; else print "no"
5344 bob.alive = (bob.name == "Hello")
5345 print "bob", "is" if bob.alive else "isn't", "alive"