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.
771 ## value union fields
779 void (*init)(struct type *type, struct value *val);
780 void (*prepare_type)(struct parse_context *c, struct type *type, int parse_time);
781 void (*print)(struct type *type, struct value *val, FILE *f);
782 void (*print_type)(struct type *type, FILE *f);
783 int (*cmp_order)(struct type *t1, struct type *t2,
784 struct value *v1, struct value *v2);
785 int (*cmp_eq)(struct type *t1, struct type *t2,
786 struct value *v1, struct value *v2);
787 void (*dup)(struct type *type, struct value *vold, struct value *vnew);
788 void (*free)(struct type *type, struct value *val);
789 void (*free_type)(struct type *t);
790 long long (*to_int)(struct value *v);
791 double (*to_float)(struct value *v);
792 int (*to_mpq)(mpq_t *q, struct value *v);
801 struct type *typelist;
805 static struct type *find_type(struct parse_context *c, struct text s)
807 struct type *l = c->typelist;
810 text_cmp(l->name, s) != 0)
815 static struct type *add_type(struct parse_context *c, struct text s,
820 n = calloc(1, sizeof(*n));
823 n->next = c->typelist;
828 static void free_type(struct type *t)
830 /* The type is always a reference to something in the
831 * context, so we don't need to free anything.
835 static void free_value(struct type *type, struct value *v)
839 memset(v, 0x5a, type->size);
843 static void type_print(struct type *type, FILE *f)
846 fputs("*unknown*type*", f); // NOTEST
847 else if (type->name.len)
848 fprintf(f, "%.*s", type->name.len, type->name.txt);
849 else if (type->print_type)
850 type->print_type(type, f);
852 fputs("*invalid*type*", f); // NOTEST
855 static void val_init(struct type *type, struct value *val)
857 if (type && type->init)
858 type->init(type, val);
861 static void dup_value(struct type *type,
862 struct value *vold, struct value *vnew)
864 if (type && type->dup)
865 type->dup(type, vold, vnew);
868 static int value_cmp(struct type *tl, struct type *tr,
869 struct value *left, struct value *right)
871 if (tl && tl->cmp_order)
872 return tl->cmp_order(tl, tr, left, right);
873 if (tl && tl->cmp_eq) // NOTEST
874 return tl->cmp_eq(tl, tr, left, right); // NOTEST
878 static void print_value(struct type *type, struct value *v, FILE *f)
880 if (type && type->print)
881 type->print(type, v, f);
883 fprintf(f, "*Unknown*"); // NOTEST
888 static void free_value(struct type *type, struct value *v);
889 static int type_compat(struct type *require, struct type *have, int rules);
890 static void type_print(struct type *type, FILE *f);
891 static void val_init(struct type *type, struct value *v);
892 static void dup_value(struct type *type,
893 struct value *vold, struct value *vnew);
894 static int value_cmp(struct type *tl, struct type *tr,
895 struct value *left, struct value *right);
896 static void print_value(struct type *type, struct value *v, FILE *f);
898 ###### free context types
900 while (context.typelist) {
901 struct type *t = context.typelist;
903 context.typelist = t->next;
909 Type can be specified for local variables, for fields in a structure,
910 for formal parameters to functions, and possibly elsewhere. Different
911 rules may apply in different contexts. As a minimum, a named type may
912 always be used. Currently the type of a formal parameter can be
913 different from types in other contexts, so we have a separate grammar
919 Type -> IDENTIFIER ${
920 $0 = find_type(c, $1.txt);
923 "error: undefined type", &$1);
930 FormalType -> Type ${ $0 = $<1; }$
931 ## formal type grammar
935 Values of the base types can be numbers, which we represent as
936 multi-precision fractions, strings, Booleans and labels. When
937 analysing the program we also need to allow for places where no value
938 is meaningful (type `Tnone`) and where we don't know what type to
939 expect yet (type is `NULL`).
941 Values are never shared, they are always copied when used, and freed
942 when no longer needed.
944 When propagating type information around the program, we need to
945 determine if two types are compatible, where type `NULL` is compatible
946 with anything. There are two special cases with type compatibility,
947 both related to the Conditional Statement which will be described
948 later. In some cases a Boolean can be accepted as well as some other
949 primary type, and in others any type is acceptable except a label (`Vlabel`).
950 A separate function encoding these cases will simplify some code later.
952 ###### type functions
954 int (*compat)(struct type *this, struct type *other);
958 static int type_compat(struct type *require, struct type *have, int rules)
960 if ((rules & Rboolok) && have == Tbool)
962 if ((rules & Rnolabel) && have == Tlabel)
964 if (!require || !have)
968 return require->compat(require, have);
970 return require == have;
975 #include "parse_string.h"
976 #include "parse_number.h"
979 myLDLIBS := libnumber.o libstring.o -lgmp
980 LDLIBS := $(filter-out $(myLDLIBS),$(LDLIBS)) $(myLDLIBS)
982 ###### type union fields
983 enum vtype {Vnone, Vstr, Vnum, Vbool, Vlabel} vtype;
985 ###### value union fields
992 static void _free_value(struct type *type, struct value *v)
996 switch (type->vtype) {
998 case Vstr: free(v->str.txt); break;
999 case Vnum: mpq_clear(v->num); break;
1005 ###### value functions
1007 static void _val_init(struct type *type, struct value *val)
1009 switch(type->vtype) {
1010 case Vnone: // NOTEST
1013 mpq_init(val->num); break;
1015 val->str.txt = malloc(1);
1027 static void _dup_value(struct type *type,
1028 struct value *vold, struct value *vnew)
1030 switch (type->vtype) {
1031 case Vnone: // NOTEST
1034 vnew->label = vold->label;
1037 vnew->bool = vold->bool;
1040 mpq_init(vnew->num);
1041 mpq_set(vnew->num, vold->num);
1044 vnew->str.len = vold->str.len;
1045 vnew->str.txt = malloc(vnew->str.len);
1046 memcpy(vnew->str.txt, vold->str.txt, vnew->str.len);
1051 static int _value_cmp(struct type *tl, struct type *tr,
1052 struct value *left, struct value *right)
1056 return tl - tr; // NOTEST
1057 switch (tl->vtype) {
1058 case Vlabel: cmp = left->label == right->label ? 0 : 1; break;
1059 case Vnum: cmp = mpq_cmp(left->num, right->num); break;
1060 case Vstr: cmp = text_cmp(left->str, right->str); break;
1061 case Vbool: cmp = left->bool - right->bool; break;
1062 case Vnone: cmp = 0; // NOTEST
1067 static void _print_value(struct type *type, struct value *v, FILE *f)
1069 switch (type->vtype) {
1070 case Vnone: // NOTEST
1071 fprintf(f, "*no-value*"); break; // NOTEST
1072 case Vlabel: // NOTEST
1073 fprintf(f, "*label-%p*", v->label); break; // NOTEST
1075 fprintf(f, "%.*s", v->str.len, v->str.txt); break;
1077 fprintf(f, "%s", v->bool ? "True":"False"); break;
1082 mpf_set_q(fl, v->num);
1083 gmp_fprintf(f, "%Fg", fl);
1090 static void _free_value(struct type *type, struct value *v);
1092 static struct type base_prototype = {
1094 .print = _print_value,
1095 .cmp_order = _value_cmp,
1096 .cmp_eq = _value_cmp,
1098 .free = _free_value,
1101 static struct type *Tbool, *Tstr, *Tnum, *Tnone, *Tlabel;
1103 ###### ast functions
1104 static struct type *add_base_type(struct parse_context *c, char *n,
1105 enum vtype vt, int size)
1107 struct text txt = { n, strlen(n) };
1110 t = add_type(c, txt, &base_prototype);
1113 t->align = size > sizeof(void*) ? sizeof(void*) : size;
1114 if (t->size & (t->align - 1))
1115 t->size = (t->size | (t->align - 1)) + 1; // NOTEST
1119 ###### context initialization
1121 Tbool = add_base_type(&context, "Boolean", Vbool, sizeof(char));
1122 Tstr = add_base_type(&context, "string", Vstr, sizeof(struct text));
1123 Tnum = add_base_type(&context, "number", Vnum, sizeof(mpq_t));
1124 Tnone = add_base_type(&context, "none", Vnone, 0);
1125 Tlabel = add_base_type(&context, "label", Vlabel, sizeof(void*));
1129 We have already met values as separate objects. When manifest constants
1130 appear in the program text, that must result in an executable which has
1131 a constant value. So the `val` structure embeds a value in an
1144 ###### ast functions
1145 struct val *new_val(struct type *T, struct token tk)
1147 struct val *v = new_pos(val, tk);
1158 $0 = new_val(Tbool, $1);
1162 $0 = new_val(Tbool, $1);
1166 $0 = new_val(Tnum, $1);
1169 if (number_parse($0->val.num, tail, $1.txt) == 0)
1170 mpq_init($0->val.num); // UNTESTED
1172 tok_err(c, "error: unsupported number suffix",
1177 $0 = new_val(Tstr, $1);
1180 string_parse(&$1, '\\', &$0->val.str, tail);
1182 tok_err(c, "error: unsupported string suffix",
1187 $0 = new_val(Tstr, $1);
1190 string_parse(&$1, '\\', &$0->val.str, tail);
1192 tok_err(c, "error: unsupported string suffix",
1197 ###### print exec cases
1200 struct val *v = cast(val, e);
1201 if (v->vtype == Tstr)
1203 print_value(v->vtype, &v->val, stdout);
1204 if (v->vtype == Tstr)
1209 ###### propagate exec cases
1212 struct val *val = cast(val, prog);
1213 if (!type_compat(type, val->vtype, rules))
1214 type_err(c, "error: expected %1%r found %2",
1215 prog, type, rules, val->vtype);
1219 ###### interp exec cases
1221 rvtype = cast(val, e)->vtype;
1222 dup_value(rvtype, &cast(val, e)->val, &rv);
1225 ###### ast functions
1226 static void free_val(struct val *v)
1229 free_value(v->vtype, &v->val);
1233 ###### free exec cases
1234 case Xval: free_val(cast(val, e)); break;
1236 ###### ast functions
1237 // Move all nodes from 'b' to 'rv', reversing their order.
1238 // In 'b' 'left' is a list, and 'right' is the last node.
1239 // In 'rv', left' is the first node and 'right' is a list.
1240 static struct binode *reorder_bilist(struct binode *b)
1242 struct binode *rv = NULL;
1245 struct exec *t = b->right;
1249 b = cast(binode, b->left);
1259 Variables are scoped named values. We store the names in a linked list
1260 of "bindings" sorted in lexical order, and use sequential search and
1267 struct binding *next; // in lexical order
1271 This linked list is stored in the parse context so that "reduce"
1272 functions can find or add variables, and so the analysis phase can
1273 ensure that every variable gets a type.
1275 ###### parse context
1277 struct binding *varlist; // In lexical order
1279 ###### ast functions
1281 static struct binding *find_binding(struct parse_context *c, struct text s)
1283 struct binding **l = &c->varlist;
1288 (cmp = text_cmp((*l)->name, s)) < 0)
1292 n = calloc(1, sizeof(*n));
1299 Each name can be linked to multiple variables defined in different
1300 scopes. Each scope starts where the name is declared and continues
1301 until the end of the containing code block. Scopes of a given name
1302 cannot nest, so a declaration while a name is in-scope is an error.
1304 ###### binding fields
1305 struct variable *var;
1309 struct variable *previous;
1311 struct binding *name;
1312 struct exec *where_decl;// where name was declared
1313 struct exec *where_set; // where type was set
1317 When a scope closes, the values of the variables might need to be freed.
1318 This happens in the context of some `struct exec` and each `exec` will
1319 need to know which variables need to be freed when it completes.
1322 struct variable *to_free;
1324 ####### variable fields
1325 struct exec *cleanup_exec;
1326 struct variable *next_free;
1328 ####### interp exec cleanup
1331 for (v = e->to_free; v; v = v->next_free) {
1332 struct value *val = var_value(c, v);
1333 free_value(v->type, val);
1337 ###### ast functions
1338 static void variable_unlink_exec(struct variable *v)
1340 struct variable **vp;
1341 if (!v->cleanup_exec)
1343 for (vp = &v->cleanup_exec->to_free;
1344 *vp; vp = &(*vp)->next_free) {
1348 v->cleanup_exec = NULL;
1353 While the naming seems strange, we include local constants in the
1354 definition of variables. A name declared `var := value` can
1355 subsequently be changed, but a name declared `var ::= value` cannot -
1358 ###### variable fields
1361 Scopes in parallel branches can be partially merged. More
1362 specifically, if a given name is declared in both branches of an
1363 if/else then its scope is a candidate for merging. Similarly if
1364 every branch of an exhaustive switch (e.g. has an "else" clause)
1365 declares a given name, then the scopes from the branches are
1366 candidates for merging.
1368 Note that names declared inside a loop (which is only parallel to
1369 itself) are never visible after the loop. Similarly names defined in
1370 scopes which are not parallel, such as those started by `for` and
1371 `switch`, are never visible after the scope. Only variables defined in
1372 both `then` and `else` (including the implicit then after an `if`, and
1373 excluding `then` used with `for`) and in all `case`s and `else` of a
1374 `switch` or `while` can be visible beyond the `if`/`switch`/`while`.
1376 Labels, which are a bit like variables, follow different rules.
1377 Labels are not explicitly declared, but if an undeclared name appears
1378 in a context where a label is legal, that effectively declares the
1379 name as a label. The declaration remains in force (or in scope) at
1380 least to the end of the immediately containing block and conditionally
1381 in any larger containing block which does not declare the name in some
1382 other way. Importantly, the conditional scope extension happens even
1383 if the label is only used in one parallel branch of a conditional --
1384 when used in one branch it is treated as having been declared in all
1387 Merge candidates are tentatively visible beyond the end of the
1388 branching statement which creates them. If the name is used, the
1389 merge is affirmed and they become a single variable visible at the
1390 outer layer. If not - if it is redeclared first - the merge lapses.
1392 To track scopes we have an extra stack, implemented as a linked list,
1393 which roughly parallels the parse stack and which is used exclusively
1394 for scoping. When a new scope is opened, a new frame is pushed and
1395 the child-count of the parent frame is incremented. This child-count
1396 is used to distinguish between the first of a set of parallel scopes,
1397 in which declared variables must not be in scope, and subsequent
1398 branches, whether they may already be conditionally scoped.
1400 We need a total ordering of scopes so we can easily compare to variables
1401 to see if they are concurrently in scope. To achieve this we record a
1402 `scope_count` which is actually a count of both beginnings and endings
1403 of scopes. Then each variable has a record of the scope count where it
1404 enters scope, and where it leaves.
1406 To push a new frame *before* any code in the frame is parsed, we need a
1407 grammar reduction. This is most easily achieved with a grammar
1408 element which derives the empty string, and creates the new scope when
1409 it is recognised. This can be placed, for example, between a keyword
1410 like "if" and the code following it.
1414 struct scope *parent;
1418 ###### parse context
1421 struct scope *scope_stack;
1423 ###### variable fields
1424 int scope_start, scope_end;
1426 ###### ast functions
1427 static void scope_pop(struct parse_context *c)
1429 struct scope *s = c->scope_stack;
1431 c->scope_stack = s->parent;
1433 c->scope_depth -= 1;
1434 c->scope_count += 1;
1437 static void scope_push(struct parse_context *c)
1439 struct scope *s = calloc(1, sizeof(*s));
1441 c->scope_stack->child_count += 1;
1442 s->parent = c->scope_stack;
1444 c->scope_depth += 1;
1445 c->scope_count += 1;
1451 OpenScope -> ${ scope_push(c); }$
1453 Each variable records a scope depth and is in one of four states:
1455 - "in scope". This is the case between the declaration of the
1456 variable and the end of the containing block, and also between
1457 the usage with affirms a merge and the end of that block.
1459 The scope depth is not greater than the current parse context scope
1460 nest depth. When the block of that depth closes, the state will
1461 change. To achieve this, all "in scope" variables are linked
1462 together as a stack in nesting order.
1464 - "pending". The "in scope" block has closed, but other parallel
1465 scopes are still being processed. So far, every parallel block at
1466 the same level that has closed has declared the name.
1468 The scope depth is the depth of the last parallel block that
1469 enclosed the declaration, and that has closed.
1471 - "conditionally in scope". The "in scope" block and all parallel
1472 scopes have closed, and no further mention of the name has been seen.
1473 This state includes a secondary nest depth (`min_depth`) which records
1474 the outermost scope seen since the variable became conditionally in
1475 scope. If a use of the name is found, the variable becomes "in scope"
1476 and that secondary depth becomes the recorded scope depth. If the
1477 name is declared as a new variable, the old variable becomes "out of
1478 scope" and the recorded scope depth stays unchanged.
1480 - "out of scope". The variable is neither in scope nor conditionally
1481 in scope. It is permanently out of scope now and can be removed from
1482 the "in scope" stack. When a variable becomes out-of-scope it is
1483 moved to a separate list (`out_scope`) of variables which have fully
1484 known scope. This will be used at the end of each function to assign
1485 each variable a place in the stack frame.
1487 ###### variable fields
1488 int depth, min_depth;
1489 enum { OutScope, PendingScope, CondScope, InScope } scope;
1490 struct variable *in_scope;
1492 ###### parse context
1494 struct variable *in_scope;
1495 struct variable *out_scope;
1497 All variables with the same name are linked together using the
1498 'previous' link. Those variable that have been affirmatively merged all
1499 have a 'merged' pointer that points to one primary variable - the most
1500 recently declared instance. When merging variables, we need to also
1501 adjust the 'merged' pointer on any other variables that had previously
1502 been merged with the one that will no longer be primary.
1504 A variable that is no longer the most recent instance of a name may
1505 still have "pending" scope, if it might still be merged with most
1506 recent instance. These variables don't really belong in the
1507 "in_scope" list, but are not immediately removed when a new instance
1508 is found. Instead, they are detected and ignored when considering the
1509 list of in_scope names.
1511 The storage of the value of a variable will be described later. For now
1512 we just need to know that when a variable goes out of scope, it might
1513 need to be freed. For this we need to be able to find it, so assume that
1514 `var_value()` will provide that.
1516 ###### variable fields
1517 struct variable *merged;
1519 ###### ast functions
1521 static void variable_merge(struct variable *primary, struct variable *secondary)
1525 primary = primary->merged;
1527 for (v = primary->previous; v; v=v->previous)
1528 if (v == secondary || v == secondary->merged ||
1529 v->merged == secondary ||
1530 v->merged == secondary->merged) {
1531 v->scope = OutScope;
1532 v->merged = primary;
1533 if (v->scope_start < primary->scope_start)
1534 primary->scope_start = v->scope_start;
1535 if (v->scope_end > primary->scope_end)
1536 primary->scope_end = v->scope_end; // NOTEST
1537 variable_unlink_exec(v);
1541 ###### forward decls
1542 static struct value *var_value(struct parse_context *c, struct variable *v);
1544 ###### free global vars
1546 while (context.varlist) {
1547 struct binding *b = context.varlist;
1548 struct variable *v = b->var;
1549 context.varlist = b->next;
1552 struct variable *next = v->previous;
1555 free_value(v->type, var_value(&context, v));
1557 // This is a global constant
1558 free_exec(v->where_decl);
1565 #### Manipulating Bindings
1567 When a name is conditionally visible, a new declaration discards the old
1568 binding - the condition lapses. Similarly when we reach the end of a
1569 function (outermost non-global scope) any conditional scope must lapse.
1570 Conversely a usage of the name affirms the visibility and extends it to
1571 the end of the containing block - i.e. the block that contains both the
1572 original declaration and the latest usage. This is determined from
1573 `min_depth`. When a conditionally visible variable gets affirmed like
1574 this, it is also merged with other conditionally visible variables with
1577 When we parse a variable declaration we either report an error if the
1578 name is currently bound, or create a new variable at the current nest
1579 depth if the name is unbound or bound to a conditionally scoped or
1580 pending-scope variable. If the previous variable was conditionally
1581 scoped, it and its homonyms becomes out-of-scope.
1583 When we parse a variable reference (including non-declarative assignment
1584 "foo = bar") we report an error if the name is not bound or is bound to
1585 a pending-scope variable; update the scope if the name is bound to a
1586 conditionally scoped variable; or just proceed normally if the named
1587 variable is in scope.
1589 When we exit a scope, any variables bound at this level are either
1590 marked out of scope or pending-scoped, depending on whether the scope
1591 was sequential or parallel. Here a "parallel" scope means the "then"
1592 or "else" part of a conditional, or any "case" or "else" branch of a
1593 switch. Other scopes are "sequential".
1595 When exiting a parallel scope we check if there are any variables that
1596 were previously pending and are still visible. If there are, then
1597 they weren't redeclared in the most recent scope, so they cannot be
1598 merged and must become out-of-scope. If it is not the first of
1599 parallel scopes (based on `child_count`), we check that there was a
1600 previous binding that is still pending-scope. If there isn't, the new
1601 variable must now be out-of-scope.
1603 When exiting a sequential scope that immediately enclosed parallel
1604 scopes, we need to resolve any pending-scope variables. If there was
1605 no `else` clause, and we cannot determine that the `switch` was exhaustive,
1606 we need to mark all pending-scope variable as out-of-scope. Otherwise
1607 all pending-scope variables become conditionally scoped.
1610 enum closetype { CloseSequential, CloseFunction, CloseParallel, CloseElse };
1612 ###### ast functions
1614 static struct variable *var_decl(struct parse_context *c, struct text s)
1616 struct binding *b = find_binding(c, s);
1617 struct variable *v = b->var;
1619 switch (v ? v->scope : OutScope) {
1621 /* Caller will report the error */
1625 v && v->scope == CondScope;
1627 v->scope = OutScope;
1631 v = calloc(1, sizeof(*v));
1632 v->previous = b->var;
1636 v->min_depth = v->depth = c->scope_depth;
1638 v->in_scope = c->in_scope;
1639 v->scope_start = c->scope_count;
1645 static struct variable *var_ref(struct parse_context *c, struct text s)
1647 struct binding *b = find_binding(c, s);
1648 struct variable *v = b->var;
1649 struct variable *v2;
1651 switch (v ? v->scope : OutScope) {
1654 /* Caller will report the error */
1657 /* All CondScope variables of this name need to be merged
1658 * and become InScope
1660 v->depth = v->min_depth;
1662 for (v2 = v->previous;
1663 v2 && v2->scope == CondScope;
1665 variable_merge(v, v2);
1673 static int var_refile(struct parse_context *c, struct variable *v)
1675 /* Variable just went out of scope. Add it to the out_scope
1676 * list, sorted by ->scope_start
1678 struct variable **vp = &c->out_scope;
1679 while ((*vp) && (*vp)->scope_start < v->scope_start)
1680 vp = &(*vp)->in_scope;
1686 static void var_block_close(struct parse_context *c, enum closetype ct,
1689 /* Close off all variables that are in_scope.
1690 * Some variables in c->scope may already be not-in-scope,
1691 * such as when a PendingScope variable is hidden by a new
1692 * variable with the same name.
1693 * So we check for v->name->var != v and drop them.
1694 * If we choose to make a variable OutScope, we drop it
1697 struct variable *v, **vp, *v2;
1700 for (vp = &c->in_scope;
1701 (v = *vp) && v->min_depth > c->scope_depth;
1702 (v->scope == OutScope || v->name->var != v)
1703 ? (*vp = v->in_scope, var_refile(c, v))
1704 : ( vp = &v->in_scope, 0)) {
1705 v->min_depth = c->scope_depth;
1706 if (v->name->var != v)
1707 /* This is still in scope, but we haven't just
1711 v->min_depth = c->scope_depth;
1712 if (v->scope == InScope)
1713 v->scope_end = c->scope_count;
1714 if (v->scope == InScope && e && !v->global) {
1715 /* This variable gets cleaned up when 'e' finishes */
1716 variable_unlink_exec(v);
1717 v->cleanup_exec = e;
1718 v->next_free = e->to_free;
1723 case CloseParallel: /* handle PendingScope */
1727 if (c->scope_stack->child_count == 1)
1728 /* first among parallel branches */
1729 v->scope = PendingScope;
1730 else if (v->previous &&
1731 v->previous->scope == PendingScope)
1732 /* all previous branches used name */
1733 v->scope = PendingScope;
1734 else if (v->type == Tlabel)
1735 /* Labels remain pending even when not used */
1736 v->scope = PendingScope; // UNTESTED
1738 v->scope = OutScope;
1739 if (ct == CloseElse) {
1740 /* All Pending variables with this name
1741 * are now Conditional */
1743 v2 && v2->scope == PendingScope;
1745 v2->scope = CondScope;
1749 /* Not possible as it would require
1750 * parallel scope to be nested immediately
1751 * in a parallel scope, and that never
1755 /* Not possible as we already tested for
1762 if (v->scope == CondScope)
1763 /* Condition cannot continue past end of function */
1766 case CloseSequential:
1767 if (v->type == Tlabel)
1768 v->scope = PendingScope;
1771 v->scope = OutScope;
1774 /* There was no 'else', so we can only become
1775 * conditional if we know the cases were exhaustive,
1776 * and that doesn't mean anything yet.
1777 * So only labels become conditional..
1780 v2 && v2->scope == PendingScope;
1782 if (v2->type == Tlabel)
1783 v2->scope = CondScope;
1785 v2->scope = OutScope;
1788 case OutScope: break;
1797 The value of a variable is store separately from the variable, on an
1798 analogue of a stack frame. There are (currently) two frames that can be
1799 active. A global frame which currently only stores constants, and a
1800 stacked frame which stores local variables. Each variable knows if it
1801 is global or not, and what its index into the frame is.
1803 Values in the global frame are known immediately they are relevant, so
1804 the frame needs to be reallocated as it grows so it can store those
1805 values. The local frame doesn't get values until the interpreted phase
1806 is started, so there is no need to allocate until the size is known.
1808 We initialize the `frame_pos` to an impossible value, so that we can
1809 tell if it was set or not later.
1811 ###### variable fields
1815 ###### variable init
1818 ###### parse context
1820 short global_size, global_alloc;
1822 void *global, *local;
1824 ###### ast functions
1826 static struct value *var_value(struct parse_context *c, struct variable *v)
1829 if (!c->local || !v->type)
1830 return NULL; // NOTEST
1831 if (v->frame_pos + v->type->size > c->local_size) {
1832 printf("INVALID frame_pos\n"); // NOTEST
1835 return c->local + v->frame_pos;
1837 if (c->global_size > c->global_alloc) {
1838 int old = c->global_alloc;
1839 c->global_alloc = (c->global_size | 1023) + 1024;
1840 c->global = realloc(c->global, c->global_alloc);
1841 memset(c->global + old, 0, c->global_alloc - old);
1843 return c->global + v->frame_pos;
1846 static struct value *global_alloc(struct parse_context *c, struct type *t,
1847 struct variable *v, struct value *init)
1850 struct variable scratch;
1852 if (t->prepare_type)
1853 t->prepare_type(c, t, 1); // NOTEST
1855 if (c->global_size & (t->align - 1))
1856 c->global_size = (c->global_size + t->align) & ~(t->align-1);
1861 v->frame_pos = c->global_size;
1863 c->global_size += v->type->size;
1864 ret = var_value(c, v);
1866 memcpy(ret, init, t->size);
1872 As global values are found -- struct field initializers, labels etc --
1873 `global_alloc()` is called to record the value in the global frame.
1875 When the program is fully parsed, each function is analysed, we need to
1876 walk the list of variables local to that function and assign them an
1877 offset in the stack frame. For this we have `scope_finalize()`.
1879 We keep the stack from dense by re-using space for between variables
1880 that are not in scope at the same time. The `out_scope` list is sorted
1881 by `scope_start` and as we process a varible, we move it to an FIFO
1882 stack. For each variable we consider, we first discard any from the
1883 stack anything that went out of scope before the new variable came in.
1884 Then we place the new variable just after the one at the top of the
1887 ###### ast functions
1889 static void scope_finalize(struct parse_context *c, struct type *ft)
1891 int size = ft->function.local_size;
1892 struct variable *next = ft->function.scope;
1893 struct variable *done = NULL;
1896 struct variable *v = next;
1897 struct type *t = v->type;
1904 if (v->frame_pos >= 0)
1906 while (done && done->scope_end < v->scope_start)
1907 done = done->in_scope;
1909 pos = done->frame_pos + done->type->size;
1911 pos = ft->function.local_size;
1912 if (pos & (t->align - 1))
1913 pos = (pos + t->align) & ~(t->align-1);
1915 if (size < pos + v->type->size)
1916 size = pos + v->type->size;
1920 c->out_scope = NULL;
1921 ft->function.local_size = size;
1924 ###### free context storage
1925 free(context.global);
1927 #### Variables as executables
1929 Just as we used a `val` to wrap a value into an `exec`, we similarly
1930 need a `var` to wrap a `variable` into an exec. While each `val`
1931 contained a copy of the value, each `var` holds a link to the variable
1932 because it really is the same variable no matter where it appears.
1933 When a variable is used, we need to remember to follow the `->merged`
1934 link to find the primary instance.
1936 When a variable is declared, it may or may not be given an explicit
1937 type. We need to record which so that we can report the parsed code
1946 struct variable *var;
1949 ###### variable fields
1957 VariableDecl -> IDENTIFIER : ${ {
1958 struct variable *v = var_decl(c, $1.txt);
1959 $0 = new_pos(var, $1);
1964 v = var_ref(c, $1.txt);
1966 type_err(c, "error: variable '%v' redeclared",
1968 type_err(c, "info: this is where '%v' was first declared",
1969 v->where_decl, NULL, 0, NULL);
1972 | IDENTIFIER :: ${ {
1973 struct variable *v = var_decl(c, $1.txt);
1974 $0 = new_pos(var, $1);
1980 v = var_ref(c, $1.txt);
1982 type_err(c, "error: variable '%v' redeclared",
1984 type_err(c, "info: this is where '%v' was first declared",
1985 v->where_decl, NULL, 0, NULL);
1988 | IDENTIFIER : Type ${ {
1989 struct variable *v = var_decl(c, $1.txt);
1990 $0 = new_pos(var, $1);
1996 v->explicit_type = 1;
1998 v = var_ref(c, $1.txt);
2000 type_err(c, "error: variable '%v' redeclared",
2002 type_err(c, "info: this is where '%v' was first declared",
2003 v->where_decl, NULL, 0, NULL);
2006 | IDENTIFIER :: Type ${ {
2007 struct variable *v = var_decl(c, $1.txt);
2008 $0 = new_pos(var, $1);
2015 v->explicit_type = 1;
2017 v = var_ref(c, $1.txt);
2019 type_err(c, "error: variable '%v' redeclared",
2021 type_err(c, "info: this is where '%v' was first declared",
2022 v->where_decl, NULL, 0, NULL);
2027 Variable -> IDENTIFIER ${ {
2028 struct variable *v = var_ref(c, $1.txt);
2029 $0 = new_pos(var, $1);
2031 /* This might be a label - allocate a var just in case */
2032 v = var_decl(c, $1.txt);
2039 cast(var, $0)->var = v;
2042 ###### print exec cases
2045 struct var *v = cast(var, e);
2047 struct binding *b = v->var->name;
2048 printf("%.*s", b->name.len, b->name.txt);
2055 if (loc && loc->type == Xvar) {
2056 struct var *v = cast(var, loc);
2058 struct binding *b = v->var->name;
2059 fprintf(stderr, "%.*s", b->name.len, b->name.txt);
2061 fputs("???", stderr); // NOTEST
2063 fputs("NOTVAR", stderr);
2066 ###### propagate exec cases
2070 struct var *var = cast(var, prog);
2071 struct variable *v = var->var;
2073 type_err(c, "%d:BUG: no variable!!", prog, NULL, 0, NULL); // NOTEST
2074 return Tnone; // NOTEST
2077 if (v->constant && (rules & Rnoconstant)) {
2078 type_err(c, "error: Cannot assign to a constant: %v",
2079 prog, NULL, 0, NULL);
2080 type_err(c, "info: name was defined as a constant here",
2081 v->where_decl, NULL, 0, NULL);
2084 if (v->type == Tnone && v->where_decl == prog)
2085 type_err(c, "error: variable used but not declared: %v",
2086 prog, NULL, 0, NULL);
2087 if (v->type == NULL) {
2088 if (type && *ok != 0) {
2090 v->where_set = prog;
2095 if (!type_compat(type, v->type, rules)) {
2096 type_err(c, "error: expected %1%r but variable '%v' is %2", prog,
2097 type, rules, v->type);
2098 type_err(c, "info: this is where '%v' was set to %1", v->where_set,
2099 v->type, rules, NULL);
2106 ###### interp exec cases
2109 struct var *var = cast(var, e);
2110 struct variable *v = var->var;
2113 lrv = var_value(c, v);
2118 ###### ast functions
2120 static void free_var(struct var *v)
2125 ###### free exec cases
2126 case Xvar: free_var(cast(var, e)); break;
2131 Now that we have the shape of the interpreter in place we can add some
2132 complex types and connected them in to the data structures and the
2133 different phases of parse, analyse, print, interpret.
2135 Being "complex" the language will naturally have syntax to access
2136 specifics of objects of these types. These will fit into the grammar as
2137 "Terms" which are the things that are combined with various operators to
2138 form "Expression". Where a Term is formed by some operation on another
2139 Term, the subordinate Term will always come first, so for example a
2140 member of an array will be expressed as the Term for the array followed
2141 by an index in square brackets. The strict rule of using postfix
2142 operations makes precedence irrelevant within terms. To provide a place
2143 to put the grammar for each terms of each type, we will start out by
2144 introducing the "Term" grammar production, with contains at least a
2145 simple "Value" (to be explained later).
2149 Term -> Value ${ $0 = $<1; }$
2150 | Variable ${ $0 = $<1; }$
2153 Thus far the complex types we have are arrays and structs.
2157 Arrays can be declared by giving a size and a type, as `[size]type' so
2158 `freq:[26]number` declares `freq` to be an array of 26 numbers. The
2159 size can be either a literal number, or a named constant. Some day an
2160 arbitrary expression will be supported.
2162 As a formal parameter to a function, the array can be declared with a
2163 new variable as the size: `name:[size::number]string`. The `size`
2164 variable is set to the size of the array and must be a constant. As
2165 `number` is the only supported type, it can be left out:
2166 `name:[size::]string`.
2168 Arrays cannot be assigned. When pointers are introduced we will also
2169 introduce array slices which can refer to part or all of an array -
2170 the assignment syntax will create a slice. For now, an array can only
2171 ever be referenced by the name it is declared with. It is likely that
2172 a "`copy`" primitive will eventually be define which can be used to
2173 make a copy of an array with controllable recursive depth.
2175 For now we have two sorts of array, those with fixed size either because
2176 it is given as a literal number or because it is a struct member (which
2177 cannot have a runtime-changing size), and those with a size that is
2178 determined at runtime - local variables with a const size. The former
2179 have their size calculated at parse time, the latter at run time.
2181 For the latter type, the `size` field of the type is the size of a
2182 pointer, and the array is reallocated every time it comes into scope.
2184 We differentiate struct fields with a const size from local variables
2185 with a const size by whether they are prepared at parse time or not.
2187 ###### type union fields
2190 int unspec; // size is unspecified - vsize must be set.
2193 struct variable *vsize;
2194 struct type *member;
2197 ###### value union fields
2198 void *array; // used if not static_size
2200 ###### value functions
2202 static void array_prepare_type(struct parse_context *c, struct type *type,
2205 struct value *vsize;
2207 if (!type->array.vsize || type->array.static_size)
2210 vsize = var_value(c, type->array.vsize);
2212 mpz_tdiv_q(q, mpq_numref(vsize->num), mpq_denref(vsize->num));
2213 type->array.size = mpz_get_si(q);
2217 type->array.static_size = 1;
2218 type->size = type->array.size * type->array.member->size;
2219 type->align = type->array.member->align;
2223 static void array_init(struct type *type, struct value *val)
2226 void *ptr = val->ptr;
2230 if (!type->array.static_size) {
2231 val->array = calloc(type->array.size,
2232 type->array.member->size);
2235 for (i = 0; i < type->array.size; i++) {
2237 v = (void*)ptr + i * type->array.member->size;
2238 val_init(type->array.member, v);
2242 static void array_free(struct type *type, struct value *val)
2245 void *ptr = val->ptr;
2247 if (!type->array.static_size)
2249 for (i = 0; i < type->array.size; i++) {
2251 v = (void*)ptr + i * type->array.member->size;
2252 free_value(type->array.member, v);
2254 if (!type->array.static_size)
2258 static int array_compat(struct type *require, struct type *have)
2260 if (have->compat != require->compat)
2262 /* Both are arrays, so we can look at details */
2263 if (!type_compat(require->array.member, have->array.member, 0))
2265 if (have->array.unspec && require->array.unspec) {
2266 if (have->array.vsize && require->array.vsize &&
2267 have->array.vsize != require->array.vsize) // UNTESTED
2268 /* sizes might not be the same */
2269 return 0; // UNTESTED
2272 if (have->array.unspec || require->array.unspec)
2273 return 1; // UNTESTED
2274 if (require->array.vsize == NULL && have->array.vsize == NULL)
2275 return require->array.size == have->array.size;
2277 return require->array.vsize == have->array.vsize; // UNTESTED
2280 static void array_print_type(struct type *type, FILE *f)
2283 if (type->array.vsize) {
2284 struct binding *b = type->array.vsize->name;
2285 fprintf(f, "%.*s%s]", b->name.len, b->name.txt,
2286 type->array.unspec ? "::" : "");
2288 fprintf(f, "%d]", type->array.size);
2289 type_print(type->array.member, f);
2292 static struct type array_prototype = {
2294 .prepare_type = array_prepare_type,
2295 .print_type = array_print_type,
2296 .compat = array_compat,
2298 .size = sizeof(void*),
2299 .align = sizeof(void*),
2302 ###### declare terminals
2307 | [ NUMBER ] Type ${ {
2310 struct text noname = { "", 0 };
2313 $0 = t = add_type(c, noname, &array_prototype);
2314 t->array.member = $<4;
2315 t->array.vsize = NULL;
2316 if (number_parse(num, tail, $2.txt) == 0)
2317 tok_err(c, "error: unrecognised number", &$2);
2319 tok_err(c, "error: unsupported number suffix", &$2);
2322 t->array.size = mpz_get_ui(mpq_numref(num));
2323 if (mpz_cmp_ui(mpq_denref(num), 1) != 0) {
2324 tok_err(c, "error: array size must be an integer",
2326 } else if (mpz_cmp_ui(mpq_numref(num), 1UL << 30) >= 0)
2327 tok_err(c, "error: array size is too large",
2331 t->array.static_size = 1;
2332 t->size = t->array.size * t->array.member->size;
2333 t->align = t->array.member->align;
2336 | [ IDENTIFIER ] Type ${ {
2337 struct variable *v = var_ref(c, $2.txt);
2338 struct text noname = { "", 0 };
2341 tok_err(c, "error: name undeclared", &$2);
2342 else if (!v->constant)
2343 tok_err(c, "error: array size must be a constant", &$2);
2345 $0 = add_type(c, noname, &array_prototype);
2346 $0->array.member = $<4;
2348 $0->array.vsize = v;
2353 OptType -> Type ${ $0 = $<1; }$
2356 ###### formal type grammar
2358 | [ IDENTIFIER :: OptType ] Type ${ {
2359 struct variable *v = var_decl(c, $ID.txt);
2360 struct text noname = { "", 0 };
2366 $0 = add_type(c, noname, &array_prototype);
2367 $0->array.member = $<6;
2369 $0->array.unspec = 1;
2370 $0->array.vsize = v;
2378 | Term [ Expression ] ${ {
2379 struct binode *b = new(binode);
2386 ###### print binode cases
2388 print_exec(b->left, -1, bracket);
2390 print_exec(b->right, -1, bracket);
2394 ###### propagate binode cases
2396 /* left must be an array, right must be a number,
2397 * result is the member type of the array
2399 propagate_types(b->right, c, ok, Tnum, 0);
2400 t = propagate_types(b->left, c, ok, NULL, rules & Rnoconstant);
2401 if (!t || t->compat != array_compat) {
2402 type_err(c, "error: %1 cannot be indexed", prog, t, 0, NULL);
2405 if (!type_compat(type, t->array.member, rules)) {
2406 type_err(c, "error: have %1 but need %2", prog,
2407 t->array.member, rules, type);
2409 return t->array.member;
2413 ###### interp binode cases
2419 lleft = linterp_exec(c, b->left, <ype);
2420 right = interp_exec(c, b->right, &rtype);
2422 mpz_tdiv_q(q, mpq_numref(right.num), mpq_denref(right.num));
2426 if (ltype->array.static_size)
2429 ptr = *(void**)lleft;
2430 rvtype = ltype->array.member;
2431 if (i >= 0 && i < ltype->array.size)
2432 lrv = ptr + i * rvtype->size;
2434 val_init(ltype->array.member, &rv); // UNSAFE
2441 A `struct` is a data-type that contains one or more other data-types.
2442 It differs from an array in that each member can be of a different
2443 type, and they are accessed by name rather than by number. Thus you
2444 cannot choose an element by calculation, you need to know what you
2447 The language makes no promises about how a given structure will be
2448 stored in memory - it is free to rearrange fields to suit whatever
2449 criteria seems important.
2451 Structs are declared separately from program code - they cannot be
2452 declared in-line in a variable declaration like arrays can. A struct
2453 is given a name and this name is used to identify the type - the name
2454 is not prefixed by the word `struct` as it would be in C.
2456 Structs are only treated as the same if they have the same name.
2457 Simply having the same fields in the same order is not enough. This
2458 might change once we can create structure initializers from a list of
2461 Each component datum is identified much like a variable is declared,
2462 with a name, one or two colons, and a type. The type cannot be omitted
2463 as there is no opportunity to deduce the type from usage. An initial
2464 value can be given following an equals sign, so
2466 ##### Example: a struct type
2472 would declare a type called "complex" which has two number fields,
2473 each initialised to zero.
2475 Struct will need to be declared separately from the code that uses
2476 them, so we will need to be able to print out the declaration of a
2477 struct when reprinting the whole program. So a `print_type_decl` type
2478 function will be needed.
2480 ###### type union fields
2492 ###### type functions
2493 void (*print_type_decl)(struct type *type, FILE *f);
2495 ###### value functions
2497 static void structure_init(struct type *type, struct value *val)
2501 for (i = 0; i < type->structure.nfields; i++) {
2503 v = (void*) val->ptr + type->structure.fields[i].offset;
2504 if (type->structure.fields[i].init)
2505 dup_value(type->structure.fields[i].type,
2506 type->structure.fields[i].init,
2509 val_init(type->structure.fields[i].type, v);
2513 static void structure_free(struct type *type, struct value *val)
2517 for (i = 0; i < type->structure.nfields; i++) {
2519 v = (void*)val->ptr + type->structure.fields[i].offset;
2520 free_value(type->structure.fields[i].type, v);
2524 static void structure_free_type(struct type *t)
2527 for (i = 0; i < t->structure.nfields; i++)
2528 if (t->structure.fields[i].init) {
2529 free_value(t->structure.fields[i].type,
2530 t->structure.fields[i].init);
2532 free(t->structure.fields);
2535 static struct type structure_prototype = {
2536 .init = structure_init,
2537 .free = structure_free,
2538 .free_type = structure_free_type,
2539 .print_type_decl = structure_print_type,
2553 ###### free exec cases
2555 free_exec(cast(fieldref, e)->left);
2559 ###### declare terminals
2564 | Term . IDENTIFIER ${ {
2565 struct fieldref *fr = new_pos(fieldref, $2);
2572 ###### print exec cases
2576 struct fieldref *f = cast(fieldref, e);
2577 print_exec(f->left, -1, bracket);
2578 printf(".%.*s", f->name.len, f->name.txt);
2582 ###### ast functions
2583 static int find_struct_index(struct type *type, struct text field)
2586 for (i = 0; i < type->structure.nfields; i++)
2587 if (text_cmp(type->structure.fields[i].name, field) == 0)
2592 ###### propagate exec cases
2596 struct fieldref *f = cast(fieldref, prog);
2597 struct type *st = propagate_types(f->left, c, ok, NULL, 0);
2600 type_err(c, "error: unknown type for field access", f->left, // UNTESTED
2602 else if (st->init != structure_init)
2603 type_err(c, "error: field reference attempted on %1, not a struct",
2604 f->left, st, 0, NULL);
2605 else if (f->index == -2) {
2606 f->index = find_struct_index(st, f->name);
2608 type_err(c, "error: cannot find requested field in %1",
2609 f->left, st, 0, NULL);
2611 if (f->index >= 0) {
2612 struct type *ft = st->structure.fields[f->index].type;
2613 if (!type_compat(type, ft, rules))
2614 type_err(c, "error: have %1 but need %2", prog,
2621 ###### interp exec cases
2624 struct fieldref *f = cast(fieldref, e);
2626 struct value *lleft = linterp_exec(c, f->left, <ype);
2627 lrv = (void*)lleft->ptr + ltype->structure.fields[f->index].offset;
2628 rvtype = ltype->structure.fields[f->index].type;
2634 struct fieldlist *prev;
2638 ###### ast functions
2639 static void free_fieldlist(struct fieldlist *f)
2643 free_fieldlist(f->prev);
2645 free_value(f->f.type, f->f.init); // UNTESTED
2646 free(f->f.init); // UNTESTED
2651 ###### top level grammar
2652 DeclareStruct -> struct IDENTIFIER FieldBlock Newlines ${ {
2654 add_type(c, $2.txt, &structure_prototype);
2656 struct fieldlist *f;
2658 for (f = $3; f; f=f->prev)
2661 t->structure.nfields = cnt;
2662 t->structure.fields = calloc(cnt, sizeof(struct field));
2665 int a = f->f.type->align;
2667 t->structure.fields[cnt] = f->f;
2668 if (t->size & (a-1))
2669 t->size = (t->size | (a-1)) + 1;
2670 t->structure.fields[cnt].offset = t->size;
2671 t->size += ((f->f.type->size - 1) | (a-1)) + 1;
2680 FieldBlock -> { IN OptNL FieldLines OUT OptNL } ${ $0 = $<FL; }$
2681 | { SimpleFieldList } ${ $0 = $<SFL; }$
2682 | IN OptNL FieldLines OUT ${ $0 = $<FL; }$
2683 | SimpleFieldList EOL ${ $0 = $<SFL; }$
2685 FieldLines -> SimpleFieldList Newlines ${ $0 = $<SFL; }$
2686 | FieldLines SimpleFieldList Newlines ${
2691 SimpleFieldList -> Field ${ $0 = $<F; }$
2692 | SimpleFieldList ; Field ${
2696 | SimpleFieldList ; ${
2699 | ERROR ${ tok_err(c, "Syntax error in struct field", &$1); }$
2701 Field -> IDENTIFIER : Type = Expression ${ {
2704 $0 = calloc(1, sizeof(struct fieldlist));
2705 $0->f.name = $1.txt;
2710 propagate_types($<5, c, &ok, $3, 0);
2713 c->parse_error = 1; // UNTESTED
2715 struct value vl = interp_exec(c, $5, NULL);
2716 $0->f.init = global_alloc(c, $0->f.type, NULL, &vl);
2719 | IDENTIFIER : Type ${
2720 $0 = calloc(1, sizeof(struct fieldlist));
2721 $0->f.name = $1.txt;
2723 if ($0->f.type->prepare_type)
2724 $0->f.type->prepare_type(c, $0->f.type, 1);
2727 ###### forward decls
2728 static void structure_print_type(struct type *t, FILE *f);
2730 ###### value functions
2731 static void structure_print_type(struct type *t, FILE *f)
2735 fprintf(f, "struct %.*s\n", t->name.len, t->name.txt);
2737 for (i = 0; i < t->structure.nfields; i++) {
2738 struct field *fl = t->structure.fields + i;
2739 fprintf(f, " %.*s : ", fl->name.len, fl->name.txt);
2740 type_print(fl->type, f);
2741 if (fl->type->print && fl->init) {
2743 if (fl->type == Tstr)
2744 fprintf(f, "\""); // UNTESTED
2745 print_value(fl->type, fl->init, f);
2746 if (fl->type == Tstr)
2747 fprintf(f, "\""); // UNTESTED
2753 ###### print type decls
2758 while (target != 0) {
2760 for (t = context.typelist; t ; t=t->next)
2761 if (t->print_type_decl && !t->check_args && t->name.txt[0] != ' ') {
2770 t->print_type_decl(t, stdout);
2778 A function is a chunk of code which can be passed parameters and can
2779 return results. Each function has a type which includes the set of
2780 parameters and the return value. As yet these types cannot be declared
2781 separately from the function itself.
2783 The parameters can be specified either in parentheses as a ';' separated
2786 ##### Example: function 1
2788 func main(av:[ac::number]string; env:[envc::number]string)
2791 or as an indented list of one parameter per line (though each line can
2792 be a ';' separated list)
2794 ##### Example: function 2
2797 argv:[argc::number]string
2798 env:[envc::number]string
2802 In the first case a return type can follow the parentheses after a colon,
2803 in the second it is given on a line starting with the word `return`.
2805 ##### Example: functions that return
2807 func add(a:number; b:number): number
2817 Rather than returning a type, the function can specify a set of local
2818 variables to return as a struct. The values of these variables when the
2819 function exits will be provided to the caller. For this the return type
2820 is replaced with a block of result declarations, either in parentheses
2821 or bracketed by `return` and `do`.
2823 ##### Example: functions returning multiple variables
2825 func to_cartesian(rho:number; theta:number):(x:number; y:number)
2838 For constructing the lists we use a `List` binode, which will be
2839 further detailed when Expression Lists are introduced.
2841 ###### type union fields
2844 struct binode *params;
2845 struct type *return_type;
2846 struct variable *scope;
2847 int inline_result; // return value is at start of 'local'
2851 ###### value union fields
2852 struct exec *function;
2854 ###### type functions
2855 void (*check_args)(struct parse_context *c, int *ok,
2856 struct type *require, struct exec *args);
2858 ###### value functions
2860 static void function_free(struct type *type, struct value *val)
2862 free_exec(val->function);
2863 val->function = NULL;
2866 static int function_compat(struct type *require, struct type *have)
2868 // FIXME can I do anything here yet?
2872 static void function_check_args(struct parse_context *c, int *ok,
2873 struct type *require, struct exec *args)
2875 /* This should be 'compat', but we don't have a 'tuple' type to
2876 * hold the type of 'args'
2878 struct binode *arg = cast(binode, args);
2879 struct binode *param = require->function.params;
2882 struct var *pv = cast(var, param->left);
2884 type_err(c, "error: insufficient arguments to function.",
2885 args, NULL, 0, NULL);
2889 propagate_types(arg->left, c, ok, pv->var->type, 0);
2890 param = cast(binode, param->right);
2891 arg = cast(binode, arg->right);
2894 type_err(c, "error: too many arguments to function.",
2895 args, NULL, 0, NULL);
2898 static void function_print(struct type *type, struct value *val, FILE *f)
2900 print_exec(val->function, 1, 0);
2903 static void function_print_type_decl(struct type *type, FILE *f)
2907 for (b = type->function.params; b; b = cast(binode, b->right)) {
2908 struct variable *v = cast(var, b->left)->var;
2909 fprintf(f, "%.*s%s", v->name->name.len, v->name->name.txt,
2910 v->constant ? "::" : ":");
2911 type_print(v->type, f);
2916 if (type->function.return_type != Tnone) {
2918 if (type->function.inline_result) {
2920 struct type *t = type->function.return_type;
2922 for (i = 0; i < t->structure.nfields; i++) {
2923 struct field *fl = t->structure.fields + i;
2926 fprintf(f, "%.*s:", fl->name.len, fl->name.txt);
2927 type_print(fl->type, f);
2931 type_print(type->function.return_type, f);
2936 static void function_free_type(struct type *t)
2938 free_exec(t->function.params);
2941 static struct type function_prototype = {
2942 .size = sizeof(void*),
2943 .align = sizeof(void*),
2944 .free = function_free,
2945 .compat = function_compat,
2946 .check_args = function_check_args,
2947 .print = function_print,
2948 .print_type_decl = function_print_type_decl,
2949 .free_type = function_free_type,
2952 ###### declare terminals
2962 FuncName -> IDENTIFIER ${ {
2963 struct variable *v = var_decl(c, $1.txt);
2964 struct var *e = new_pos(var, $1);
2970 v = var_ref(c, $1.txt);
2972 type_err(c, "error: function '%v' redeclared",
2974 type_err(c, "info: this is where '%v' was first declared",
2975 v->where_decl, NULL, 0, NULL);
2981 Args -> ArgsLine NEWLINE ${ $0 = $<AL; }$
2982 | Args ArgsLine NEWLINE ${ {
2983 struct binode *b = $<AL;
2984 struct binode **bp = &b;
2986 bp = (struct binode **)&(*bp)->left;
2991 ArgsLine -> ${ $0 = NULL; }$
2992 | Varlist ${ $0 = $<1; }$
2993 | Varlist ; ${ $0 = $<1; }$
2995 Varlist -> Varlist ; ArgDecl ${
3009 ArgDecl -> IDENTIFIER : FormalType ${ {
3010 struct variable *v = var_decl(c, $1.txt);
3016 ##### Function calls
3018 A function call can appear either as an expression or as a statement.
3019 We use a new 'Funcall' binode type to link the function with a list of
3020 arguments, form with the 'List' nodes.
3022 We have already seen the "Term" which is how a function call can appear
3023 in an expression. To parse a function call into a statement we include
3024 it in the "SimpleStatement Grammar" which will be described later.
3030 | Term ( ExpressionList ) ${ {
3031 struct binode *b = new(binode);
3034 b->right = reorder_bilist($<EL);
3038 struct binode *b = new(binode);
3045 ###### SimpleStatement Grammar
3047 | Term ( ExpressionList ) ${ {
3048 struct binode *b = new(binode);
3051 b->right = reorder_bilist($<EL);
3055 ###### print binode cases
3058 do_indent(indent, "");
3059 print_exec(b->left, -1, bracket);
3061 for (b = cast(binode, b->right); b; b = cast(binode, b->right)) {
3064 print_exec(b->left, -1, bracket);
3074 ###### propagate binode cases
3077 /* Every arg must match formal parameter, and result
3078 * is return type of function
3080 struct binode *args = cast(binode, b->right);
3081 struct var *v = cast(var, b->left);
3083 if (!v->var->type || v->var->type->check_args == NULL) {
3084 type_err(c, "error: attempt to call a non-function.",
3085 prog, NULL, 0, NULL);
3088 v->var->type->check_args(c, ok, v->var->type, args);
3089 return v->var->type->function.return_type;
3092 ###### interp binode cases
3095 struct var *v = cast(var, b->left);
3096 struct type *t = v->var->type;
3097 void *oldlocal = c->local;
3098 int old_size = c->local_size;
3099 void *local = calloc(1, t->function.local_size);
3100 struct value *fbody = var_value(c, v->var);
3101 struct binode *arg = cast(binode, b->right);
3102 struct binode *param = t->function.params;
3105 struct var *pv = cast(var, param->left);
3106 struct type *vtype = NULL;
3107 struct value val = interp_exec(c, arg->left, &vtype);
3109 c->local = local; c->local_size = t->function.local_size;
3110 lval = var_value(c, pv->var);
3111 c->local = oldlocal; c->local_size = old_size;
3112 memcpy(lval, &val, vtype->size);
3113 param = cast(binode, param->right);
3114 arg = cast(binode, arg->right);
3116 c->local = local; c->local_size = t->function.local_size;
3117 if (t->function.inline_result && dtype) {
3118 _interp_exec(c, fbody->function, NULL, NULL);
3119 memcpy(dest, local, dtype->size);
3120 rvtype = ret.type = NULL;
3122 rv = interp_exec(c, fbody->function, &rvtype);
3123 c->local = oldlocal; c->local_size = old_size;
3128 ## Complex executables: statements and expressions
3130 Now that we have types and values and variables and most of the basic
3131 Terms which provide access to these, we can explore the more complex
3132 code that combine all of these to get useful work done. Specifically
3133 statements and expressions.
3135 Expressions are various combinations of Terms. We will use operator
3136 precedence to ensure correct parsing. The simplest Expression is just a
3137 Term - others will follow.
3142 Expression -> Term ${ $0 = $<Term; }$
3143 ## expression grammar
3145 ### Expressions: Conditional
3147 Our first user of the `binode` will be conditional expressions, which
3148 is a bit odd as they actually have three components. That will be
3149 handled by having 2 binodes for each expression. The conditional
3150 expression is the lowest precedence operator which is why we define it
3151 first - to start the precedence list.
3153 Conditional expressions are of the form "value `if` condition `else`
3154 other_value". They associate to the right, so everything to the right
3155 of `else` is part of an else value, while only a higher-precedence to
3156 the left of `if` is the if values. Between `if` and `else` there is no
3157 room for ambiguity, so a full conditional expression is allowed in
3163 ###### declare terminals
3167 ###### expression grammar
3169 | Expression if Expression else Expression $$ifelse ${ {
3170 struct binode *b1 = new(binode);
3171 struct binode *b2 = new(binode);
3181 ###### print binode cases
3184 b2 = cast(binode, b->right);
3185 if (bracket) printf("(");
3186 print_exec(b2->left, -1, bracket);
3188 print_exec(b->left, -1, bracket);
3190 print_exec(b2->right, -1, bracket);
3191 if (bracket) printf(")");
3194 ###### propagate binode cases
3197 /* cond must be Tbool, others must match */
3198 struct binode *b2 = cast(binode, b->right);
3201 propagate_types(b->left, c, ok, Tbool, 0);
3202 t = propagate_types(b2->left, c, ok, type, Rnolabel);
3203 t2 = propagate_types(b2->right, c, ok, type ?: t, Rnolabel);
3207 ###### interp binode cases
3210 struct binode *b2 = cast(binode, b->right);
3211 left = interp_exec(c, b->left, <ype);
3213 rv = interp_exec(c, b2->left, &rvtype); // UNTESTED
3215 rv = interp_exec(c, b2->right, &rvtype);
3221 We take a brief detour, now that we have expressions, to describe lists
3222 of expressions. These will be needed for function parameters and
3223 possibly other situations. They seem generic enough to introduce here
3224 to be used elsewhere.
3226 And ExpressionList will use the `List` type of `binode`, building up at
3227 the end. And place where they are used will probably call
3228 `reorder_bilist()` to get a more normal first/next arrangement.
3230 ###### declare terminals
3233 `List` execs have no implicit semantics, so they are never propagated or
3234 interpreted. The can be printed as a comma separate list, which is how
3235 they are parsed. Note they are also used for function formal parameter
3236 lists. In that case a separate function is used to print them.
3238 ###### print binode cases
3242 print_exec(b->left, -1, bracket);
3245 b = cast(binode, b->right);
3249 ###### propagate binode cases
3250 case List: abort(); // NOTEST
3251 ###### interp binode cases
3252 case List: abort(); // NOTEST
3257 ExpressionList -> ExpressionList , Expression ${
3270 ### Expressions: Boolean
3272 The next class of expressions to use the `binode` will be Boolean
3273 expressions. "`and then`" and "`or else`" are similar to `and` and `or`
3274 have same corresponding precendence. The difference is that they don't
3275 evaluate the second expression if not necessary.
3284 ###### declare terminals
3289 ###### expression grammar
3290 | Expression or Expression ${ {
3291 struct binode *b = new(binode);
3297 | Expression or else Expression ${ {
3298 struct binode *b = new(binode);
3305 | Expression and Expression ${ {
3306 struct binode *b = new(binode);
3312 | Expression and then Expression ${ {
3313 struct binode *b = new(binode);
3320 | not Expression ${ {
3321 struct binode *b = new(binode);
3327 ###### print binode cases
3329 if (bracket) printf("(");
3330 print_exec(b->left, -1, bracket);
3332 print_exec(b->right, -1, bracket);
3333 if (bracket) printf(")");
3336 if (bracket) printf("(");
3337 print_exec(b->left, -1, bracket);
3338 printf(" and then ");
3339 print_exec(b->right, -1, bracket);
3340 if (bracket) printf(")");
3343 if (bracket) printf("(");
3344 print_exec(b->left, -1, bracket);
3346 print_exec(b->right, -1, bracket);
3347 if (bracket) printf(")");
3350 if (bracket) printf("(");
3351 print_exec(b->left, -1, bracket);
3352 printf(" or else ");
3353 print_exec(b->right, -1, bracket);
3354 if (bracket) printf(")");
3357 if (bracket) printf("(");
3359 print_exec(b->right, -1, bracket);
3360 if (bracket) printf(")");
3363 ###### propagate binode cases
3369 /* both must be Tbool, result is Tbool */
3370 propagate_types(b->left, c, ok, Tbool, 0);
3371 propagate_types(b->right, c, ok, Tbool, 0);
3372 if (type && type != Tbool)
3373 type_err(c, "error: %1 operation found where %2 expected", prog,
3377 ###### interp binode cases
3379 rv = interp_exec(c, b->left, &rvtype);
3380 right = interp_exec(c, b->right, &rtype);
3381 rv.bool = rv.bool && right.bool;
3384 rv = interp_exec(c, b->left, &rvtype);
3386 rv = interp_exec(c, b->right, NULL);
3389 rv = interp_exec(c, b->left, &rvtype);
3390 right = interp_exec(c, b->right, &rtype);
3391 rv.bool = rv.bool || right.bool;
3394 rv = interp_exec(c, b->left, &rvtype);
3396 rv = interp_exec(c, b->right, NULL);
3399 rv = interp_exec(c, b->right, &rvtype);
3403 ### Expressions: Comparison
3405 Of slightly higher precedence that Boolean expressions are Comparisons.
3406 A comparison takes arguments of any comparable type, but the two types
3409 To simplify the parsing we introduce an `eop` which can record an
3410 expression operator, and the `CMPop` non-terminal will match one of them.
3417 ###### ast functions
3418 static void free_eop(struct eop *e)
3432 ###### declare terminals
3433 $LEFT < > <= >= == != CMPop
3435 ###### expression grammar
3436 | Expression CMPop Expression ${ {
3437 struct binode *b = new(binode);
3447 CMPop -> < ${ $0.op = Less; }$
3448 | > ${ $0.op = Gtr; }$
3449 | <= ${ $0.op = LessEq; }$
3450 | >= ${ $0.op = GtrEq; }$
3451 | == ${ $0.op = Eql; }$
3452 | != ${ $0.op = NEql; }$
3454 ###### print binode cases
3462 if (bracket) printf("(");
3463 print_exec(b->left, -1, bracket);
3465 case Less: printf(" < "); break;
3466 case LessEq: printf(" <= "); break;
3467 case Gtr: printf(" > "); break;
3468 case GtrEq: printf(" >= "); break;
3469 case Eql: printf(" == "); break;
3470 case NEql: printf(" != "); break;
3471 default: abort(); // NOTEST
3473 print_exec(b->right, -1, bracket);
3474 if (bracket) printf(")");
3477 ###### propagate binode cases
3484 /* Both must match but not be labels, result is Tbool */
3485 t = propagate_types(b->left, c, ok, NULL, Rnolabel);
3487 propagate_types(b->right, c, ok, t, 0);
3489 t = propagate_types(b->right, c, ok, NULL, Rnolabel); // UNTESTED
3491 t = propagate_types(b->left, c, ok, t, 0); // UNTESTED
3493 if (!type_compat(type, Tbool, 0))
3494 type_err(c, "error: Comparison returns %1 but %2 expected", prog,
3495 Tbool, rules, type);
3498 ###### interp binode cases
3507 left = interp_exec(c, b->left, <ype);
3508 right = interp_exec(c, b->right, &rtype);
3509 cmp = value_cmp(ltype, rtype, &left, &right);
3512 case Less: rv.bool = cmp < 0; break;
3513 case LessEq: rv.bool = cmp <= 0; break;
3514 case Gtr: rv.bool = cmp > 0; break;
3515 case GtrEq: rv.bool = cmp >= 0; break;
3516 case Eql: rv.bool = cmp == 0; break;
3517 case NEql: rv.bool = cmp != 0; break;
3518 default: rv.bool = 0; break; // NOTEST
3523 ### Expressions: Arithmetic etc.
3525 The remaining expressions with the highest precedence are arithmetic,
3526 string concatenation, and string conversion. String concatenation
3527 (`++`) has the same precedence as multiplication and division, but lower
3530 String conversion is a temporary feature until I get a better type
3531 system. `$` is a prefix operator which expects a string and returns
3534 `+` and `-` are both infix and prefix operations (where they are
3535 absolute value and negation). These have different operator names.
3537 We also have a 'Bracket' operator which records where parentheses were
3538 found. This makes it easy to reproduce these when printing. Possibly I
3539 should only insert brackets were needed for precedence. Putting
3540 parentheses around an expression converts it into a Term,
3550 ###### declare terminals
3556 ###### expression grammar
3557 | Expression Eop Expression ${ {
3558 struct binode *b = new(binode);
3565 | Expression Top Expression ${ {
3566 struct binode *b = new(binode);
3573 | Uop Expression ${ {
3574 struct binode *b = new(binode);
3582 | ( Expression ) ${ {
3583 struct binode *b = new_pos(binode, $1);
3592 Eop -> + ${ $0.op = Plus; }$
3593 | - ${ $0.op = Minus; }$
3595 Uop -> + ${ $0.op = Absolute; }$
3596 | - ${ $0.op = Negate; }$
3597 | $ ${ $0.op = StringConv; }$
3599 Top -> * ${ $0.op = Times; }$
3600 | / ${ $0.op = Divide; }$
3601 | % ${ $0.op = Rem; }$
3602 | ++ ${ $0.op = Concat; }$
3604 ###### print binode cases
3611 if (bracket) printf("(");
3612 print_exec(b->left, indent, bracket);
3614 case Plus: fputs(" + ", stdout); break;
3615 case Minus: fputs(" - ", stdout); break;
3616 case Times: fputs(" * ", stdout); break;
3617 case Divide: fputs(" / ", stdout); break;
3618 case Rem: fputs(" % ", stdout); break;
3619 case Concat: fputs(" ++ ", stdout); break;
3620 default: abort(); // NOTEST
3622 print_exec(b->right, indent, bracket);
3623 if (bracket) printf(")");
3628 if (bracket) printf("(");
3630 case Absolute: fputs("+", stdout); break;
3631 case Negate: fputs("-", stdout); break;
3632 case StringConv: fputs("$", stdout); break;
3633 default: abort(); // NOTEST
3635 print_exec(b->right, indent, bracket);
3636 if (bracket) printf(")");
3640 print_exec(b->right, indent, bracket);
3644 ###### propagate binode cases
3650 /* both must be numbers, result is Tnum */
3653 /* as propagate_types ignores a NULL,
3654 * unary ops fit here too */
3655 propagate_types(b->left, c, ok, Tnum, 0);
3656 propagate_types(b->right, c, ok, Tnum, 0);
3657 if (!type_compat(type, Tnum, 0))
3658 type_err(c, "error: Arithmetic returns %1 but %2 expected", prog,
3663 /* both must be Tstr, result is Tstr */
3664 propagate_types(b->left, c, ok, Tstr, 0);
3665 propagate_types(b->right, c, ok, Tstr, 0);
3666 if (!type_compat(type, Tstr, 0))
3667 type_err(c, "error: Concat returns %1 but %2 expected", prog,
3672 /* op must be string, result is number */
3673 propagate_types(b->left, c, ok, Tstr, 0);
3674 if (!type_compat(type, Tnum, 0))
3675 type_err(c, // UNTESTED
3676 "error: Can only convert string to number, not %1",
3677 prog, type, 0, NULL);
3681 return propagate_types(b->right, c, ok, type, 0);
3683 ###### interp binode cases
3686 rv = interp_exec(c, b->left, &rvtype);
3687 right = interp_exec(c, b->right, &rtype);
3688 mpq_add(rv.num, rv.num, right.num);
3691 rv = interp_exec(c, b->left, &rvtype);
3692 right = interp_exec(c, b->right, &rtype);
3693 mpq_sub(rv.num, rv.num, right.num);
3696 rv = interp_exec(c, b->left, &rvtype);
3697 right = interp_exec(c, b->right, &rtype);
3698 mpq_mul(rv.num, rv.num, right.num);
3701 rv = interp_exec(c, b->left, &rvtype);
3702 right = interp_exec(c, b->right, &rtype);
3703 mpq_div(rv.num, rv.num, right.num);
3708 left = interp_exec(c, b->left, <ype);
3709 right = interp_exec(c, b->right, &rtype);
3710 mpz_init(l); mpz_init(r); mpz_init(rem);
3711 mpz_tdiv_q(l, mpq_numref(left.num), mpq_denref(left.num));
3712 mpz_tdiv_q(r, mpq_numref(right.num), mpq_denref(right.num));
3713 mpz_tdiv_r(rem, l, r);
3714 val_init(Tnum, &rv);
3715 mpq_set_z(rv.num, rem);
3716 mpz_clear(r); mpz_clear(l); mpz_clear(rem);
3721 rv = interp_exec(c, b->right, &rvtype);
3722 mpq_neg(rv.num, rv.num);
3725 rv = interp_exec(c, b->right, &rvtype);
3726 mpq_abs(rv.num, rv.num);
3729 rv = interp_exec(c, b->right, &rvtype);
3732 left = interp_exec(c, b->left, <ype);
3733 right = interp_exec(c, b->right, &rtype);
3735 rv.str = text_join(left.str, right.str);
3738 right = interp_exec(c, b->right, &rvtype);
3742 struct text tx = right.str;
3745 if (tx.txt[0] == '-') {
3746 neg = 1; // UNTESTED
3747 tx.txt++; // UNTESTED
3748 tx.len--; // UNTESTED
3750 if (number_parse(rv.num, tail, tx) == 0)
3751 mpq_init(rv.num); // UNTESTED
3753 mpq_neg(rv.num, rv.num); // UNTESTED
3755 printf("Unsupported suffix: %.*s\n", tx.len, tx.txt); // UNTESTED
3759 ###### value functions
3761 static struct text text_join(struct text a, struct text b)
3764 rv.len = a.len + b.len;
3765 rv.txt = malloc(rv.len);
3766 memcpy(rv.txt, a.txt, a.len);
3767 memcpy(rv.txt+a.len, b.txt, b.len);
3771 ### Blocks, Statements, and Statement lists.
3773 Now that we have expressions out of the way we need to turn to
3774 statements. There are simple statements and more complex statements.
3775 Simple statements do not contain (syntactic) newlines, complex statements do.
3777 Statements often come in sequences and we have corresponding simple
3778 statement lists and complex statement lists.
3779 The former comprise only simple statements separated by semicolons.
3780 The later comprise complex statements and simple statement lists. They are
3781 separated by newlines. Thus the semicolon is only used to separate
3782 simple statements on the one line. This may be overly restrictive,
3783 but I'm not sure I ever want a complex statement to share a line with
3786 Note that a simple statement list can still use multiple lines if
3787 subsequent lines are indented, so
3789 ###### Example: wrapped simple statement list
3794 is a single simple statement list. This might allow room for
3795 confusion, so I'm not set on it yet.
3797 A simple statement list needs no extra syntax. A complex statement
3798 list has two syntactic forms. It can be enclosed in braces (much like
3799 C blocks), or it can be introduced by an indent and continue until an
3800 unindented newline (much like Python blocks). With this extra syntax
3801 it is referred to as a block.
3803 Note that a block does not have to include any newlines if it only
3804 contains simple statements. So both of:
3806 if condition: a=b; d=f
3808 if condition { a=b; print f }
3812 In either case the list is constructed from a `binode` list with
3813 `Block` as the operator. When parsing the list it is most convenient
3814 to append to the end, so a list is a list and a statement. When using
3815 the list it is more convenient to consider a list to be a statement
3816 and a list. So we need a function to re-order a list.
3817 `reorder_bilist` serves this purpose.
3819 The only stand-alone statement we introduce at this stage is `pass`
3820 which does nothing and is represented as a `NULL` pointer in a `Block`
3821 list. Other stand-alone statements will follow once the infrastructure
3824 As many statements will use binodes, we declare a binode pointer 'b' in
3825 the common header for all reductions to use.
3827 ###### Parser: reduce
3838 Block -> { IN OptNL Statementlist OUT OptNL } ${ $0 = $<Sl; }$
3839 | { SimpleStatements } ${ $0 = reorder_bilist($<SS); }$
3840 | SimpleStatements ; ${ $0 = reorder_bilist($<SS); }$
3841 | SimpleStatements EOL ${ $0 = reorder_bilist($<SS); }$
3842 | IN OptNL Statementlist OUT ${ $0 = $<Sl; }$
3844 OpenBlock -> OpenScope { IN OptNL Statementlist OUT OptNL } ${ $0 = $<Sl; }$
3845 | OpenScope { SimpleStatements } ${ $0 = reorder_bilist($<SS); }$
3846 | OpenScope SimpleStatements ; ${ $0 = reorder_bilist($<SS); }$
3847 | OpenScope SimpleStatements EOL ${ $0 = reorder_bilist($<SS); }$
3848 | IN OpenScope OptNL Statementlist OUT ${ $0 = $<Sl; }$
3850 UseBlock -> { OpenScope IN OptNL Statementlist OUT OptNL } ${ $0 = $<Sl; }$
3851 | { OpenScope SimpleStatements } ${ $0 = reorder_bilist($<SS); }$
3852 | IN OpenScope OptNL Statementlist OUT ${ $0 = $<Sl; }$
3854 ColonBlock -> { IN OptNL Statementlist OUT OptNL } ${ $0 = $<Sl; }$
3855 | { SimpleStatements } ${ $0 = reorder_bilist($<SS); }$
3856 | : SimpleStatements ; ${ $0 = reorder_bilist($<SS); }$
3857 | : SimpleStatements EOL ${ $0 = reorder_bilist($<SS); }$
3858 | : IN OptNL Statementlist OUT ${ $0 = $<Sl; }$
3860 Statementlist -> ComplexStatements ${ $0 = reorder_bilist($<CS); }$
3862 ComplexStatements -> ComplexStatements ComplexStatement ${
3872 | ComplexStatement ${
3884 ComplexStatement -> SimpleStatements Newlines ${
3885 $0 = reorder_bilist($<SS);
3887 | SimpleStatements ; Newlines ${
3888 $0 = reorder_bilist($<SS);
3890 ## ComplexStatement Grammar
3893 SimpleStatements -> SimpleStatements ; SimpleStatement ${
3899 | SimpleStatement ${
3908 SimpleStatement -> pass ${ $0 = NULL; }$
3909 | ERROR ${ tok_err(c, "Syntax error in statement", &$1); }$
3910 ## SimpleStatement Grammar
3912 ###### print binode cases
3916 if (b->left == NULL) // UNTESTED
3917 printf("pass"); // UNTESTED
3919 print_exec(b->left, indent, bracket); // UNTESTED
3920 if (b->right) { // UNTESTED
3921 printf("; "); // UNTESTED
3922 print_exec(b->right, indent, bracket); // UNTESTED
3925 // block, one per line
3926 if (b->left == NULL)
3927 do_indent(indent, "pass\n");
3929 print_exec(b->left, indent, bracket);
3931 print_exec(b->right, indent, bracket);
3935 ###### propagate binode cases
3938 /* If any statement returns something other than Tnone
3939 * or Tbool then all such must return same type.
3940 * As each statement may be Tnone or something else,
3941 * we must always pass NULL (unknown) down, otherwise an incorrect
3942 * error might occur. We never return Tnone unless it is
3947 for (e = b; e; e = cast(binode, e->right)) {
3948 t = propagate_types(e->left, c, ok, NULL, rules);
3949 if ((rules & Rboolok) && (t == Tbool || t == Tnone))
3951 if (t == Tnone && e->right)
3952 /* Only the final statement *must* return a value
3960 type_err(c, "error: expected %1%r, found %2",
3961 e->left, type, rules, t);
3967 ###### interp binode cases
3969 while (rvtype == Tnone &&
3972 rv = interp_exec(c, b->left, &rvtype);
3973 b = cast(binode, b->right);
3977 ### The Print statement
3979 `print` is a simple statement that takes a comma-separated list of
3980 expressions and prints the values separated by spaces and terminated
3981 by a newline. No control of formatting is possible.
3983 `print` uses `ExpressionList` to collect the expressions and stores them
3984 on the left side of a `Print` binode unlessthere is a trailing comma
3985 when the list is stored on the `right` side and no trailing newline is
3991 ##### declare terminals
3994 ###### SimpleStatement Grammar
3996 | print ExpressionList ${
3997 $0 = b = new(binode);
4000 b->left = reorder_bilist($<EL);
4002 | print ExpressionList , ${ {
4003 $0 = b = new(binode);
4005 b->right = reorder_bilist($<EL);
4009 $0 = b = new(binode);
4015 ###### print binode cases
4018 do_indent(indent, "print");
4020 print_exec(b->right, -1, bracket);
4023 print_exec(b->left, -1, bracket);
4028 ###### propagate binode cases
4031 /* don't care but all must be consistent */
4033 b = cast(binode, b->left);
4035 b = cast(binode, b->right);
4037 propagate_types(b->left, c, ok, NULL, Rnolabel);
4038 b = cast(binode, b->right);
4042 ###### interp binode cases
4046 struct binode *b2 = cast(binode, b->left);
4048 b2 = cast(binode, b->right);
4049 for (; b2; b2 = cast(binode, b2->right)) {
4050 left = interp_exec(c, b2->left, <ype);
4051 print_value(ltype, &left, stdout);
4052 free_value(ltype, &left);
4056 if (b->right == NULL)
4062 ###### Assignment statement
4064 An assignment will assign a value to a variable, providing it hasn't
4065 been declared as a constant. The analysis phase ensures that the type
4066 will be correct so the interpreter just needs to perform the
4067 calculation. There is a form of assignment which declares a new
4068 variable as well as assigning a value. If a name is assigned before
4069 it is declared, and error will be raised as the name is created as
4070 `Tlabel` and it is illegal to assign to such names.
4076 ###### declare terminals
4079 ###### SimpleStatement Grammar
4080 | Term = Expression ${
4081 $0 = b= new(binode);
4086 | VariableDecl = Expression ${
4087 $0 = b= new(binode);
4094 if ($1->var->where_set == NULL) {
4096 "Variable declared with no type or value: %v",
4100 $0 = b = new(binode);
4107 ###### print binode cases
4110 do_indent(indent, "");
4111 print_exec(b->left, indent, bracket);
4113 print_exec(b->right, indent, bracket);
4120 struct variable *v = cast(var, b->left)->var;
4121 do_indent(indent, "");
4122 print_exec(b->left, indent, bracket);
4123 if (cast(var, b->left)->var->constant) {
4125 if (v->explicit_type) {
4126 type_print(v->type, stdout);
4131 if (v->explicit_type) {
4132 type_print(v->type, stdout);
4138 print_exec(b->right, indent, bracket);
4145 ###### propagate binode cases
4149 /* Both must match and not be labels,
4150 * Type must support 'dup',
4151 * For Assign, left must not be constant.
4154 t = propagate_types(b->left, c, ok, NULL,
4155 Rnolabel | (b->op == Assign ? Rnoconstant : 0));
4160 if (propagate_types(b->right, c, ok, t, 0) != t)
4161 if (b->left->type == Xvar)
4162 type_err(c, "info: variable '%v' was set as %1 here.",
4163 cast(var, b->left)->var->where_set, t, rules, NULL);
4165 t = propagate_types(b->right, c, ok, NULL, Rnolabel);
4167 propagate_types(b->left, c, ok, t,
4168 (b->op == Assign ? Rnoconstant : 0));
4170 if (t && t->dup == NULL && t->name.txt[0] != ' ') // HACK
4171 type_err(c, "error: cannot assign value of type %1", b, t, 0, NULL);
4176 ###### interp binode cases
4179 lleft = linterp_exec(c, b->left, <ype);
4181 dinterp_exec(c, b->right, lleft, ltype, 1);
4187 struct variable *v = cast(var, b->left)->var;
4190 val = var_value(c, v);
4191 if (v->type->prepare_type)
4192 v->type->prepare_type(c, v->type, 0);
4194 dinterp_exec(c, b->right, val, v->type, 0);
4196 val_init(v->type, val);
4200 ### The `use` statement
4202 The `use` statement is the last "simple" statement. It is needed when a
4203 statement block can return a value. This includes the body of a
4204 function which has a return type, and the "condition" code blocks in
4205 `if`, `while`, and `switch` statements.
4210 ###### declare terminals
4213 ###### SimpleStatement Grammar
4215 $0 = b = new_pos(binode, $1);
4218 if (b->right->type == Xvar) {
4219 struct var *v = cast(var, b->right);
4220 if (v->var->type == Tnone) {
4221 /* Convert this to a label */
4224 v->var->type = Tlabel;
4225 val = global_alloc(c, Tlabel, v->var, NULL);
4231 ###### print binode cases
4234 do_indent(indent, "use ");
4235 print_exec(b->right, -1, bracket);
4240 ###### propagate binode cases
4243 /* result matches value */
4244 return propagate_types(b->right, c, ok, type, 0);
4246 ###### interp binode cases
4249 rv = interp_exec(c, b->right, &rvtype);
4252 ### The Conditional Statement
4254 This is the biggy and currently the only complex statement. This
4255 subsumes `if`, `while`, `do/while`, `switch`, and some parts of `for`.
4256 It is comprised of a number of parts, all of which are optional though
4257 set combinations apply. Each part is (usually) a key word (`then` is
4258 sometimes optional) followed by either an expression or a code block,
4259 except the `casepart` which is a "key word and an expression" followed
4260 by a code block. The code-block option is valid for all parts and,
4261 where an expression is also allowed, the code block can use the `use`
4262 statement to report a value. If the code block does not report a value
4263 the effect is similar to reporting `True`.
4265 The `else` and `case` parts, as well as `then` when combined with
4266 `if`, can contain a `use` statement which will apply to some
4267 containing conditional statement. `for` parts, `do` parts and `then`
4268 parts used with `for` can never contain a `use`, except in some
4269 subordinate conditional statement.
4271 If there is a `forpart`, it is executed first, only once.
4272 If there is a `dopart`, then it is executed repeatedly providing
4273 always that the `condpart` or `cond`, if present, does not return a non-True
4274 value. `condpart` can fail to return any value if it simply executes
4275 to completion. This is treated the same as returning `True`.
4277 If there is a `thenpart` it will be executed whenever the `condpart`
4278 or `cond` returns True (or does not return any value), but this will happen
4279 *after* `dopart` (when present).
4281 If `elsepart` is present it will be executed at most once when the
4282 condition returns `False` or some value that isn't `True` and isn't
4283 matched by any `casepart`. If there are any `casepart`s, they will be
4284 executed when the condition returns a matching value.
4286 The particular sorts of values allowed in case parts has not yet been
4287 determined in the language design, so nothing is prohibited.
4289 The various blocks in this complex statement potentially provide scope
4290 for variables as described earlier. Each such block must include the
4291 "OpenScope" nonterminal before parsing the block, and must call
4292 `var_block_close()` when closing the block.
4294 The code following "`if`", "`switch`" and "`for`" does not get its own
4295 scope, but is in a scope covering the whole statement, so names
4296 declared there cannot be redeclared elsewhere. Similarly the
4297 condition following "`while`" is in a scope the covers the body
4298 ("`do`" part) of the loop, and which does not allow conditional scope
4299 extension. Code following "`then`" (both looping and non-looping),
4300 "`else`" and "`case`" each get their own local scope.
4302 The type requirements on the code block in a `whilepart` are quite
4303 unusal. It is allowed to return a value of some identifiable type, in
4304 which case the loop aborts and an appropriate `casepart` is run, or it
4305 can return a Boolean, in which case the loop either continues to the
4306 `dopart` (on `True`) or aborts and runs the `elsepart` (on `False`).
4307 This is different both from the `ifpart` code block which is expected to
4308 return a Boolean, or the `switchpart` code block which is expected to
4309 return the same type as the casepart values. The correct analysis of
4310 the type of the `whilepart` code block is the reason for the
4311 `Rboolok` flag which is passed to `propagate_types()`.
4313 The `cond_statement` cannot fit into a `binode` so a new `exec` is
4314 defined. As there are two scopes which cover multiple parts - one for
4315 the whole statement and one for "while" and "do" - and as we will use
4316 the 'struct exec' to track scopes, we actually need two new types of
4317 exec. One is a `binode` for the looping part, the rest is the
4318 `cond_statement`. The `cond_statement` will use an auxilliary `struct
4319 casepart` to track a list of case parts.
4330 struct exec *action;
4331 struct casepart *next;
4333 struct cond_statement {
4335 struct exec *forpart, *condpart, *thenpart, *elsepart;
4336 struct binode *looppart;
4337 struct casepart *casepart;
4340 ###### ast functions
4342 static void free_casepart(struct casepart *cp)
4346 free_exec(cp->value);
4347 free_exec(cp->action);
4354 static void free_cond_statement(struct cond_statement *s)
4358 free_exec(s->forpart);
4359 free_exec(s->condpart);
4360 free_exec(s->looppart);
4361 free_exec(s->thenpart);
4362 free_exec(s->elsepart);
4363 free_casepart(s->casepart);
4367 ###### free exec cases
4368 case Xcond_statement: free_cond_statement(cast(cond_statement, e)); break;
4370 ###### ComplexStatement Grammar
4371 | CondStatement ${ $0 = $<1; }$
4373 ###### declare terminals
4374 $TERM for then while do
4381 // A CondStatement must end with EOL, as does CondSuffix and
4383 // ForPart, ThenPart, SwitchPart, CasePart are non-empty and
4384 // may or may not end with EOL
4385 // WhilePart and IfPart include an appropriate Suffix
4387 // ForPart, SwitchPart, and IfPart open scopes, o we have to close
4388 // them. WhilePart opens and closes its own scope.
4389 CondStatement -> ForPart OptNL ThenPart OptNL WhilePart CondSuffix ${
4392 $0->thenpart = $<TP;
4393 $0->looppart = $<WP;
4394 var_block_close(c, CloseSequential, $0);
4396 | ForPart OptNL WhilePart CondSuffix ${
4399 $0->looppart = $<WP;
4400 var_block_close(c, CloseSequential, $0);
4402 | WhilePart CondSuffix ${
4404 $0->looppart = $<WP;
4406 | SwitchPart OptNL CasePart CondSuffix ${
4408 $0->condpart = $<SP;
4409 $CP->next = $0->casepart;
4410 $0->casepart = $<CP;
4411 var_block_close(c, CloseSequential, $0);
4413 | SwitchPart : IN OptNL CasePart CondSuffix OUT Newlines ${
4415 $0->condpart = $<SP;
4416 $CP->next = $0->casepart;
4417 $0->casepart = $<CP;
4418 var_block_close(c, CloseSequential, $0);
4420 | IfPart IfSuffix ${
4422 $0->condpart = $IP.condpart; $IP.condpart = NULL;
4423 $0->thenpart = $IP.thenpart; $IP.thenpart = NULL;
4424 // This is where we close an "if" statement
4425 var_block_close(c, CloseSequential, $0);
4428 CondSuffix -> IfSuffix ${
4431 | Newlines CasePart CondSuffix ${
4433 $CP->next = $0->casepart;
4434 $0->casepart = $<CP;
4436 | CasePart CondSuffix ${
4438 $CP->next = $0->casepart;
4439 $0->casepart = $<CP;
4442 IfSuffix -> Newlines ${ $0 = new(cond_statement); }$
4443 | Newlines ElsePart ${ $0 = $<EP; }$
4444 | ElsePart ${$0 = $<EP; }$
4446 ElsePart -> else OpenBlock Newlines ${
4447 $0 = new(cond_statement);
4448 $0->elsepart = $<OB;
4449 var_block_close(c, CloseElse, $0->elsepart);
4451 | else OpenScope CondStatement ${
4452 $0 = new(cond_statement);
4453 $0->elsepart = $<CS;
4454 var_block_close(c, CloseElse, $0->elsepart);
4458 CasePart -> case Expression OpenScope ColonBlock ${
4459 $0 = calloc(1,sizeof(struct casepart));
4462 var_block_close(c, CloseParallel, $0->action);
4466 // These scopes are closed in CondStatement
4467 ForPart -> for OpenBlock ${
4471 ThenPart -> then OpenBlock ${
4473 var_block_close(c, CloseSequential, $0);
4477 // This scope is closed in CondStatement
4478 WhilePart -> while UseBlock OptNL do OpenBlock ${
4483 var_block_close(c, CloseSequential, $0->right);
4484 var_block_close(c, CloseSequential, $0);
4486 | while OpenScope Expression OpenScope ColonBlock ${
4491 var_block_close(c, CloseSequential, $0->right);
4492 var_block_close(c, CloseSequential, $0);
4496 IfPart -> if UseBlock OptNL then OpenBlock ${
4499 var_block_close(c, CloseParallel, $0.thenpart);
4501 | if OpenScope Expression OpenScope ColonBlock ${
4504 var_block_close(c, CloseParallel, $0.thenpart);
4506 | if OpenScope Expression OpenScope OptNL then Block ${
4509 var_block_close(c, CloseParallel, $0.thenpart);
4513 // This scope is closed in CondStatement
4514 SwitchPart -> switch OpenScope Expression ${
4517 | switch UseBlock ${
4521 ###### print binode cases
4523 if (b->left && b->left->type == Xbinode &&
4524 cast(binode, b->left)->op == Block) {
4526 do_indent(indent, "while {\n");
4528 do_indent(indent, "while\n");
4529 print_exec(b->left, indent+1, bracket);
4531 do_indent(indent, "} do {\n");
4533 do_indent(indent, "do\n");
4534 print_exec(b->right, indent+1, bracket);
4536 do_indent(indent, "}\n");
4538 do_indent(indent, "while ");
4539 print_exec(b->left, 0, bracket);
4544 print_exec(b->right, indent+1, bracket);
4546 do_indent(indent, "}\n");
4550 ###### print exec cases
4552 case Xcond_statement:
4554 struct cond_statement *cs = cast(cond_statement, e);
4555 struct casepart *cp;
4557 do_indent(indent, "for");
4558 if (bracket) printf(" {\n"); else printf("\n");
4559 print_exec(cs->forpart, indent+1, bracket);
4562 do_indent(indent, "} then {\n");
4564 do_indent(indent, "then\n");
4565 print_exec(cs->thenpart, indent+1, bracket);
4567 if (bracket) do_indent(indent, "}\n");
4570 print_exec(cs->looppart, indent, bracket);
4574 do_indent(indent, "switch");
4576 do_indent(indent, "if");
4577 if (cs->condpart && cs->condpart->type == Xbinode &&
4578 cast(binode, cs->condpart)->op == Block) {
4583 print_exec(cs->condpart, indent+1, bracket);
4585 do_indent(indent, "}\n");
4587 do_indent(indent, "then\n");
4588 print_exec(cs->thenpart, indent+1, bracket);
4592 print_exec(cs->condpart, 0, bracket);
4598 print_exec(cs->thenpart, indent+1, bracket);
4600 do_indent(indent, "}\n");
4605 for (cp = cs->casepart; cp; cp = cp->next) {
4606 do_indent(indent, "case ");
4607 print_exec(cp->value, -1, 0);
4612 print_exec(cp->action, indent+1, bracket);
4614 do_indent(indent, "}\n");
4617 do_indent(indent, "else");
4622 print_exec(cs->elsepart, indent+1, bracket);
4624 do_indent(indent, "}\n");
4629 ###### propagate binode cases
4631 t = propagate_types(b->right, c, ok, Tnone, 0);
4632 if (!type_compat(Tnone, t, 0))
4633 *ok = 0; // UNTESTED
4634 return propagate_types(b->left, c, ok, type, rules);
4636 ###### propagate exec cases
4637 case Xcond_statement:
4639 // forpart and looppart->right must return Tnone
4640 // thenpart must return Tnone if there is a loopart,
4641 // otherwise it is like elsepart.
4643 // be bool if there is no casepart
4644 // match casepart->values if there is a switchpart
4645 // either be bool or match casepart->value if there
4647 // elsepart and casepart->action must match the return type
4648 // expected of this statement.
4649 struct cond_statement *cs = cast(cond_statement, prog);
4650 struct casepart *cp;
4652 t = propagate_types(cs->forpart, c, ok, Tnone, 0);
4653 if (!type_compat(Tnone, t, 0))
4654 *ok = 0; // UNTESTED
4657 t = propagate_types(cs->thenpart, c, ok, Tnone, 0);
4658 if (!type_compat(Tnone, t, 0))
4659 *ok = 0; // UNTESTED
4661 if (cs->casepart == NULL) {
4662 propagate_types(cs->condpart, c, ok, Tbool, 0);
4663 propagate_types(cs->looppart, c, ok, Tbool, 0);
4665 /* Condpart must match case values, with bool permitted */
4667 for (cp = cs->casepart;
4668 cp && !t; cp = cp->next)
4669 t = propagate_types(cp->value, c, ok, NULL, 0);
4670 if (!t && cs->condpart)
4671 t = propagate_types(cs->condpart, c, ok, NULL, Rboolok); // UNTESTED
4672 if (!t && cs->looppart)
4673 t = propagate_types(cs->looppart, c, ok, NULL, Rboolok); // UNTESTED
4674 // Now we have a type (I hope) push it down
4676 for (cp = cs->casepart; cp; cp = cp->next)
4677 propagate_types(cp->value, c, ok, t, 0);
4678 propagate_types(cs->condpart, c, ok, t, Rboolok);
4679 propagate_types(cs->looppart, c, ok, t, Rboolok);
4682 // (if)then, else, and case parts must return expected type.
4683 if (!cs->looppart && !type)
4684 type = propagate_types(cs->thenpart, c, ok, NULL, rules);
4686 type = propagate_types(cs->elsepart, c, ok, NULL, rules);
4687 for (cp = cs->casepart;
4689 cp = cp->next) // UNTESTED
4690 type = propagate_types(cp->action, c, ok, NULL, rules); // UNTESTED
4693 propagate_types(cs->thenpart, c, ok, type, rules);
4694 propagate_types(cs->elsepart, c, ok, type, rules);
4695 for (cp = cs->casepart; cp ; cp = cp->next)
4696 propagate_types(cp->action, c, ok, type, rules);
4702 ###### interp binode cases
4704 // This just performs one iterration of the loop
4705 rv = interp_exec(c, b->left, &rvtype);
4706 if (rvtype == Tnone ||
4707 (rvtype == Tbool && rv.bool != 0))
4708 // rvtype is Tnone or Tbool, doesn't need to be freed
4709 interp_exec(c, b->right, NULL);
4712 ###### interp exec cases
4713 case Xcond_statement:
4715 struct value v, cnd;
4716 struct type *vtype, *cndtype;
4717 struct casepart *cp;
4718 struct cond_statement *cs = cast(cond_statement, e);
4721 interp_exec(c, cs->forpart, NULL);
4723 while ((cnd = interp_exec(c, cs->looppart, &cndtype)),
4724 cndtype == Tnone || (cndtype == Tbool && cnd.bool != 0))
4725 interp_exec(c, cs->thenpart, NULL);
4727 cnd = interp_exec(c, cs->condpart, &cndtype);
4728 if ((cndtype == Tnone ||
4729 (cndtype == Tbool && cnd.bool != 0))) {
4730 // cnd is Tnone or Tbool, doesn't need to be freed
4731 rv = interp_exec(c, cs->thenpart, &rvtype);
4732 // skip else (and cases)
4736 for (cp = cs->casepart; cp; cp = cp->next) {
4737 v = interp_exec(c, cp->value, &vtype);
4738 if (value_cmp(cndtype, vtype, &v, &cnd) == 0) {
4739 free_value(vtype, &v);
4740 free_value(cndtype, &cnd);
4741 rv = interp_exec(c, cp->action, &rvtype);
4744 free_value(vtype, &v);
4746 free_value(cndtype, &cnd);
4748 rv = interp_exec(c, cs->elsepart, &rvtype);
4755 ### Top level structure
4757 All the language elements so far can be used in various places. Now
4758 it is time to clarify what those places are.
4760 At the top level of a file there will be a number of declarations.
4761 Many of the things that can be declared haven't been described yet,
4762 such as functions, procedures, imports, and probably more.
4763 For now there are two sorts of things that can appear at the top
4764 level. They are predefined constants, `struct` types, and the `main`
4765 function. While the syntax will allow the `main` function to appear
4766 multiple times, that will trigger an error if it is actually attempted.
4768 The various declarations do not return anything. They store the
4769 various declarations in the parse context.
4771 ###### Parser: grammar
4774 Ocean -> OptNL DeclarationList
4776 ## declare terminals
4783 DeclarationList -> Declaration
4784 | DeclarationList Declaration
4786 Declaration -> ERROR Newlines ${
4787 tok_err(c, // UNTESTED
4788 "error: unhandled parse error", &$1);
4794 ## top level grammar
4798 ### The `const` section
4800 As well as being defined in with the code that uses them, constants
4801 can be declared at the top level. These have full-file scope, so they
4802 are always `InScope`. The value of a top level constant can be given
4803 as an expression, and this is evaluated immediately rather than in the
4804 later interpretation stage. Once we add functions to the language, we
4805 will need rules concern which, if any, can be used to define a top
4808 Constants are defined in a section that starts with the reserved word
4809 `const` and then has a block with a list of assignment statements.
4810 For syntactic consistency, these must use the double-colon syntax to
4811 make it clear that they are constants. Type can also be given: if
4812 not, the type will be determined during analysis, as with other
4815 As the types constants are inserted at the head of a list, printing
4816 them in the same order that they were read is not straight forward.
4817 We take a quadratic approach here and count the number of constants
4818 (variables of depth 0), then count down from there, each time
4819 searching through for the Nth constant for decreasing N.
4821 ###### top level grammar
4825 DeclareConstant -> const { IN OptNL ConstList OUT OptNL } Newlines
4826 | const { SimpleConstList } Newlines
4827 | const IN OptNL ConstList OUT Newlines
4828 | const SimpleConstList Newlines
4830 ConstList -> ConstList SimpleConstLine
4832 SimpleConstList -> SimpleConstList ; Const
4835 SimpleConstLine -> SimpleConstList Newlines
4836 | ERROR Newlines ${ tok_err(c, "Syntax error in constant", &$1); }$
4839 CType -> Type ${ $0 = $<1; }$
4842 Const -> IDENTIFIER :: CType = Expression ${ {
4846 v = var_decl(c, $1.txt);
4848 struct var *var = new_pos(var, $1);
4849 v->where_decl = var;
4855 struct variable *vorig = var_ref(c, $1.txt);
4856 tok_err(c, "error: name already declared", &$1);
4857 type_err(c, "info: this is where '%v' was first declared",
4858 vorig->where_decl, NULL, 0, NULL);
4862 propagate_types($5, c, &ok, $3, 0);
4867 struct value res = interp_exec(c, $5, &v->type);
4868 global_alloc(c, v->type, v, &res);
4872 ###### print const decls
4877 while (target != 0) {
4879 for (v = context.in_scope; v; v=v->in_scope)
4880 if (v->depth == 0 && v->constant) {
4891 struct value *val = var_value(&context, v);
4892 printf(" %.*s :: ", v->name->name.len, v->name->name.txt);
4893 type_print(v->type, stdout);
4895 if (v->type == Tstr)
4897 print_value(v->type, val, stdout);
4898 if (v->type == Tstr)
4906 ### Function declarations
4908 The code in an Ocean program is all stored in function declarations.
4909 One of the functions must be named `main` and it must accept an array of
4910 strings as a parameter - the command line arguments.
4912 As this is the top level, several things are handled a bit differently.
4913 The function is not interpreted by `interp_exec` as that isn't passed
4914 the argument list which the program requires. Similarly type analysis
4915 is a bit more interesting at this level.
4917 ###### ast functions
4919 static struct type *handle_results(struct parse_context *c,
4920 struct binode *results)
4922 /* Create a 'struct' type from the results list, which
4923 * is a list for 'struct var'
4925 struct text result_type_name = { " function_result", 5 };
4926 struct type *t = add_type(c, result_type_name, &structure_prototype);
4930 for (b = results; b; b = cast(binode, b->right))
4932 t->structure.nfields = cnt;
4933 t->structure.fields = calloc(cnt, sizeof(struct field));
4935 for (b = results; b; b = cast(binode, b->right)) {
4936 struct var *v = cast(var, b->left);
4937 struct field *f = &t->structure.fields[cnt++];
4938 int a = v->var->type->align;
4939 f->name = v->var->name->name;
4940 f->type = v->var->type;
4942 f->offset = t->size;
4943 v->var->frame_pos = f->offset;
4944 t->size += ((f->type->size - 1) | (a-1)) + 1;
4947 variable_unlink_exec(v->var);
4949 free_binode(results);
4953 static struct variable *declare_function(struct parse_context *c,
4954 struct variable *name,
4955 struct binode *args,
4957 struct binode *results,
4960 struct text funcname = {" func", 5};
4962 struct value fn = {.function = code};
4964 var_block_close(c, CloseFunction, code);
4965 t = add_type(c, funcname, &function_prototype);
4967 t->function.params = reorder_bilist(args);
4969 ret = handle_results(c, reorder_bilist(results));
4970 t->function.inline_result = 1;
4971 t->function.local_size = ret->size;
4973 t->function.return_type = ret;
4974 global_alloc(c, t, name, &fn);
4975 name->type->function.scope = c->out_scope;
4980 var_block_close(c, CloseFunction, NULL);
4982 c->out_scope = NULL;
4986 ###### declare terminals
4989 ###### top level grammar
4992 DeclareFunction -> func FuncName ( OpenScope ArgsLine ) Block Newlines ${
4993 $0 = declare_function(c, $<FN, $<Ar, Tnone, NULL, $<Bl);
4995 | func FuncName IN OpenScope Args OUT OptNL do Block Newlines ${
4996 $0 = declare_function(c, $<FN, $<Ar, Tnone, NULL, $<Bl);
4998 | func FuncName NEWLINE OpenScope OptNL do Block Newlines ${
4999 $0 = declare_function(c, $<FN, NULL, Tnone, NULL, $<Bl);
5001 | func FuncName ( OpenScope ArgsLine ) : Type Block Newlines ${
5002 $0 = declare_function(c, $<FN, $<Ar, $<Ty, NULL, $<Bl);
5004 | func FuncName ( OpenScope ArgsLine ) : ( ArgsLine ) Block Newlines ${
5005 $0 = declare_function(c, $<FN, $<AL, NULL, $<AL2, $<Bl);
5007 | func FuncName IN OpenScope Args OUT OptNL return Type Newlines do Block Newlines ${
5008 $0 = declare_function(c, $<FN, $<Ar, $<Ty, NULL, $<Bl);
5010 | func FuncName NEWLINE OpenScope return Type Newlines do Block Newlines ${
5011 $0 = declare_function(c, $<FN, NULL, $<Ty, NULL, $<Bl);
5013 | func FuncName IN OpenScope Args OUT OptNL return IN Args OUT OptNL do Block Newlines ${
5014 $0 = declare_function(c, $<FN, $<Ar, NULL, $<Ar2, $<Bl);
5016 | func FuncName NEWLINE OpenScope return IN Args OUT OptNL do Block Newlines ${
5017 $0 = declare_function(c, $<FN, NULL, NULL, $<Ar, $<Bl);
5020 ###### print func decls
5025 while (target != 0) {
5027 for (v = context.in_scope; v; v=v->in_scope)
5028 if (v->depth == 0 && v->type && v->type->check_args) {
5037 struct value *val = var_value(&context, v);
5038 printf("func %.*s", v->name->name.len, v->name->name.txt);
5039 v->type->print_type_decl(v->type, stdout);
5041 print_exec(val->function, 0, brackets);
5043 print_value(v->type, val, stdout);
5044 printf("/* frame size %d */\n", v->type->function.local_size);
5050 ###### core functions
5052 static int analyse_funcs(struct parse_context *c)
5056 for (v = c->in_scope; v; v = v->in_scope) {
5060 if (v->depth != 0 || !v->type || !v->type->check_args)
5062 ret = v->type->function.inline_result ?
5063 Tnone : v->type->function.return_type;
5064 val = var_value(c, v);
5067 propagate_types(val->function, c, &ok, ret, 0);
5070 /* Make sure everything is still consistent */
5071 propagate_types(val->function, c, &ok, ret, 0);
5074 if (!v->type->function.inline_result &&
5075 !v->type->function.return_type->dup) {
5076 type_err(c, "error: function cannot return value of type %1",
5077 v->where_decl, v->type->function.return_type, 0, NULL);
5080 scope_finalize(c, v->type);
5085 static int analyse_main(struct type *type, struct parse_context *c)
5087 struct binode *bp = type->function.params;
5091 struct type *argv_type;
5092 struct text argv_type_name = { " argv", 5 };
5094 argv_type = add_type(c, argv_type_name, &array_prototype);
5095 argv_type->array.member = Tstr;
5096 argv_type->array.unspec = 1;
5098 for (b = bp; b; b = cast(binode, b->right)) {
5102 propagate_types(b->left, c, &ok, argv_type, 0);
5104 default: /* invalid */ // NOTEST
5105 propagate_types(b->left, c, &ok, Tnone, 0); // NOTEST
5111 return !c->parse_error;
5114 static void interp_main(struct parse_context *c, int argc, char **argv)
5116 struct value *progp = NULL;
5117 struct text main_name = { "main", 4 };
5118 struct variable *mainv;
5124 mainv = var_ref(c, main_name);
5126 progp = var_value(c, mainv);
5127 if (!progp || !progp->function) {
5128 fprintf(stderr, "oceani: no main function found.\n");
5132 if (!analyse_main(mainv->type, c)) {
5133 fprintf(stderr, "oceani: main has wrong type.\n");
5137 al = mainv->type->function.params;
5139 c->local_size = mainv->type->function.local_size;
5140 c->local = calloc(1, c->local_size);
5142 struct var *v = cast(var, al->left);
5143 struct value *vl = var_value(c, v->var);
5153 mpq_set_ui(argcq, argc, 1);
5154 memcpy(var_value(c, t->array.vsize), &argcq, sizeof(argcq));
5155 t->prepare_type(c, t, 0);
5156 array_init(v->var->type, vl);
5157 for (i = 0; i < argc; i++) {
5158 struct value *vl2 = vl->array + i * v->var->type->array.member->size;
5160 arg.str.txt = argv[i];
5161 arg.str.len = strlen(argv[i]);
5162 free_value(Tstr, vl2);
5163 dup_value(Tstr, &arg, vl2);
5167 al = cast(binode, al->right);
5169 v = interp_exec(c, progp->function, &vtype);
5170 free_value(vtype, &v);
5175 ###### ast functions
5176 void free_variable(struct variable *v)
5180 ## And now to test it out.
5182 Having a language requires having a "hello world" program. I'll
5183 provide a little more than that: a program that prints "Hello world"
5184 finds the GCD of two numbers, prints the first few elements of
5185 Fibonacci, performs a binary search for a number, and a few other
5186 things which will likely grow as the languages grows.
5188 ###### File: oceani.mk
5191 @echo "===== DEMO ====="
5192 ./oceani --section "demo: hello" oceani.mdc 55 33
5198 four ::= 2 + 2 ; five ::= 10/2
5199 const pie ::= "I like Pie";
5200 cake ::= "The cake is"
5208 func main(argv:[argc::]string)
5209 print "Hello World, what lovely oceans you have!"
5210 print "Are there", five, "?"
5211 print pi, pie, "but", cake
5213 A := $argv[1]; B := $argv[2]
5215 /* When a variable is defined in both branches of an 'if',
5216 * and used afterwards, the variables are merged.
5222 print "Is", A, "bigger than", B,"? ", bigger
5223 /* If a variable is not used after the 'if', no
5224 * merge happens, so types can be different
5227 double:string = "yes"
5228 print A, "is more than twice", B, "?", double
5231 print "double", B, "is", double
5236 if a > 0 and then b > 0:
5242 print "GCD of", A, "and", B,"is", a
5244 print a, "is not positive, cannot calculate GCD"
5246 print b, "is not positive, cannot calculate GCD"
5251 print "Fibonacci:", f1,f2,
5252 then togo = togo - 1
5260 /* Binary search... */
5265 mid := (lo + hi) / 2
5278 print "Yay, I found", target
5280 print "Closest I found was", lo
5285 // "middle square" PRNG. Not particularly good, but one my
5286 // Dad taught me - the first one I ever heard of.
5287 for i:=1; then i = i + 1; while i < size:
5288 n := list[i-1] * list[i-1]
5289 list[i] = (n / 100) % 10 000
5291 print "Before sort:",
5292 for i:=0; then i = i + 1; while i < size:
5296 for i := 1; then i=i+1; while i < size:
5297 for j:=i-1; then j=j-1; while j >= 0:
5298 if list[j] > list[j+1]:
5302 print " After sort:",
5303 for i:=0; then i = i + 1; while i < size:
5307 if 1 == 2 then print "yes"; else print "no"
5311 bob.alive = (bob.name == "Hello")
5312 print "bob", "is" if bob.alive else "isn't", "alive"