1 # Ocean Interpreter - Jamison Creek version
3 Ocean is intended to be a compiled language, so this interpreter is
4 not targeted at being the final product. It is, rather, an intermediate
5 stage and fills that role in two distinct ways.
7 Firstly, it exists as a platform to experiment with the early language
8 design. An interpreter is easy to write and easy to get working, so
9 the barrier for entry is lower if I aim to start with an interpreter.
11 Secondly, the plan for the Ocean compiler is to write it in the
12 [Ocean language](http://ocean-lang.org). To achieve this we naturally
13 need some sort of boot-strap process and this interpreter - written in
14 portable C - will fill that role. It will be used to bootstrap the
17 Two features that are not needed to fill either of these roles are
18 performance and completeness. The interpreter only needs to be fast
19 enough to run small test programs and occasionally to run the compiler
20 on itself. It only needs to be complete enough to test aspects of the
21 design which are developed before the compiler is working, and to run
22 the compiler on itself. Any features not used by the compiler when
23 compiling itself are superfluous. They may be included anyway, but
26 Nonetheless, the interpreter should end up being reasonably complete,
27 and any performance bottlenecks which appear and are easily fixed, will
32 This third version of the interpreter exists to test out some initial
33 ideas relating to types. Particularly it adds arrays (indexed from
34 zero) and simple structures. Basic control flow and variable scoping
35 are already fairly well established, as are basic numerical and
38 Some operators that have only recently been added, and so have not
39 generated all that much experience yet are "and then" and "or else" as
40 short-circuit Boolean operators, and the "if ... else" trinary
41 operator which can select between two expressions based on a third
42 (which appears syntactically in the middle).
44 The "func" clause currently only allows a "main" function to be
45 declared. That will be extended when proper function support is added.
47 An element that is present purely to make a usable language, and
48 without any expectation that they will remain, is the "print" statement
49 which performs simple output.
51 The current scalar types are "number", "Boolean", and "string".
52 Boolean will likely stay in its current form, the other two might, but
53 could just as easily be changed.
57 Versions of the interpreter which obviously do not support a complete
58 language will be named after creeks and streams. This one is Jamison
61 Once we have something reasonably resembling a complete language, the
62 names of rivers will be used.
63 Early versions of the compiler will be named after seas. Major
64 releases of the compiler will be named after oceans. Hopefully I will
65 be finished once I get to the Pacific Ocean release.
69 As well as parsing and executing a program, the interpreter can print
70 out the program from the parsed internal structure. This is useful
71 for validating the parsing.
72 So the main requirements of the interpreter are:
74 - Parse the program, possibly with tracing,
75 - Analyse the parsed program to ensure consistency,
77 - Execute the "main" function in the program, if no parsing or
78 consistency errors were found.
80 This is all performed by a single C program extracted with
83 There will be two formats for printing the program: a default and one
84 that uses bracketing. So a `--bracket` command line option is needed
85 for that. Normally the first code section found is used, however an
86 alternate section can be requested so that a file (such as this one)
87 can contain multiple programs. This is effected with the `--section`
90 This code must be compiled with `-fplan9-extensions` so that anonymous
91 structures can be used.
93 ###### File: oceani.mk
95 myCFLAGS := -Wall -g -fplan9-extensions
96 CFLAGS := $(filter-out $(myCFLAGS),$(CFLAGS)) $(myCFLAGS)
97 myLDLIBS:= libparser.o libscanner.o libmdcode.o -licuuc
98 LDLIBS := $(filter-out $(myLDLIBS),$(LDLIBS)) $(myLDLIBS)
100 all :: $(LDLIBS) oceani
101 oceani.c oceani.h : oceani.mdc parsergen
102 ./parsergen -o oceani --LALR --tag Parser oceani.mdc
103 oceani.mk: oceani.mdc md2c
106 oceani: oceani.o $(LDLIBS)
107 $(CC) $(CFLAGS) -o oceani oceani.o $(LDLIBS)
109 ###### Parser: header
111 struct parse_context;
113 struct parse_context {
114 struct token_config config;
122 #define container_of(ptr, type, member) ({ \
123 const typeof( ((type *)0)->member ) *__mptr = (ptr); \
124 (type *)( (char *)__mptr - offsetof(type,member) );})
126 #define config2context(_conf) container_of(_conf, struct parse_context, \
129 ###### Parser: reduce
130 struct parse_context *c = config2context(config);
138 #include <sys/mman.h>
157 static char Usage[] =
158 "Usage: oceani --trace --print --noexec --brackets --section=SectionName prog.ocn\n";
159 static const struct option long_options[] = {
160 {"trace", 0, NULL, 't'},
161 {"print", 0, NULL, 'p'},
162 {"noexec", 0, NULL, 'n'},
163 {"brackets", 0, NULL, 'b'},
164 {"section", 1, NULL, 's'},
167 const char *options = "tpnbs";
169 static void pr_err(char *msg) // NOTEST
171 fprintf(stderr, "%s\n", msg); // NOTEST
174 int main(int argc, char *argv[])
179 struct section *s = NULL, *ss;
180 char *section = NULL;
181 struct parse_context context = {
183 .ignored = (1 << TK_mark),
184 .number_chars = ".,_+- ",
189 int doprint=0, dotrace=0, doexec=1, brackets=0;
191 while ((opt = getopt_long(argc, argv, options, long_options, NULL))
194 case 't': dotrace=1; break;
195 case 'p': doprint=1; break;
196 case 'n': doexec=0; break;
197 case 'b': brackets=1; break;
198 case 's': section = optarg; break;
199 default: fprintf(stderr, Usage);
203 if (optind >= argc) {
204 fprintf(stderr, "oceani: no input file given\n");
207 fd = open(argv[optind], O_RDONLY);
209 fprintf(stderr, "oceani: cannot open %s\n", argv[optind]);
212 context.file_name = argv[optind];
213 len = lseek(fd, 0, 2);
214 file = mmap(NULL, len, PROT_READ, MAP_SHARED, fd, 0);
215 s = code_extract(file, file+len, pr_err);
217 fprintf(stderr, "oceani: could not find any code in %s\n",
222 ## context initialization
225 for (ss = s; ss; ss = ss->next) {
226 struct text sec = ss->section;
227 if (sec.len == strlen(section) &&
228 strncmp(sec.txt, section, sec.len) == 0)
232 fprintf(stderr, "oceani: cannot find section %s\n",
239 fprintf(stderr, "oceani: no code found in requested section\n"); // NOTEST
240 goto cleanup; // NOTEST
243 parse_oceani(ss->code, &context.config, dotrace ? stderr : NULL);
245 if (!context.parse_error && !analyse_funcs(&context)) {
246 fprintf(stderr, "oceani: type error in program - not running.\n");
247 context.parse_error = 1;
255 if (doexec && !context.parse_error)
256 interp_main(&context, argc - optind, argv + optind);
259 struct section *t = s->next;
264 // FIXME parser should pop scope even on error
265 while (context.scope_depth > 0)
268 ## free context types
269 ## free context storage
270 exit(context.parse_error ? 1 : 0);
275 The four requirements of parse, analyse, print, interpret apply to
276 each language element individually so that is how most of the code
279 Three of the four are fairly self explanatory. The one that requires
280 a little explanation is the analysis step.
282 The current language design does not require the types of variables to
283 be declared, but they must still have a single type. Different
284 operations impose different requirements on the variables, for example
285 addition requires both arguments to be numeric, and assignment
286 requires the variable on the left to have the same type as the
287 expression on the right.
289 Analysis involves propagating these type requirements around and
290 consequently setting the type of each variable. If any requirements
291 are violated (e.g. a string is compared with a number) or if a
292 variable needs to have two different types, then an error is raised
293 and the program will not run.
295 If the same variable is declared in both branchs of an 'if/else', or
296 in all cases of a 'switch' then the multiple instances may be merged
297 into just one variable if the variable is referenced after the
298 conditional statement. When this happens, the types must naturally be
299 consistent across all the branches. When the variable is not used
300 outside the if, the variables in the different branches are distinct
301 and can be of different types.
303 Undeclared names may only appear in "use" statements and "case" expressions.
304 These names are given a type of "label" and a unique value.
305 This allows them to fill the role of a name in an enumerated type, which
306 is useful for testing the `switch` statement.
308 As we will see, the condition part of a `while` statement can return
309 either a Boolean or some other type. This requires that the expected
310 type that gets passed around comprises a type and a flag to indicate
311 that `Tbool` is also permitted.
313 As there are, as yet, no distinct types that are compatible, there
314 isn't much subtlety in the analysis. When we have distinct number
315 types, this will become more interesting.
319 When analysis discovers an inconsistency it needs to report an error;
320 just refusing to run the code ensures that the error doesn't cascade,
321 but by itself it isn't very useful. A clear understanding of the sort
322 of error message that are useful will help guide the process of
325 At a simplistic level, the only sort of error that type analysis can
326 report is that the type of some construct doesn't match a contextual
327 requirement. For example, in `4 + "hello"` the addition provides a
328 contextual requirement for numbers, but `"hello"` is not a number. In
329 this particular example no further information is needed as the types
330 are obvious from local information. When a variable is involved that
331 isn't the case. It may be helpful to explain why the variable has a
332 particular type, by indicating the location where the type was set,
333 whether by declaration or usage.
335 Using a recursive-descent analysis we can easily detect a problem at
336 multiple locations. In "`hello:= "there"; 4 + hello`" the addition
337 will detect that one argument is not a number and the usage of `hello`
338 will detect that a number was wanted, but not provided. In this
339 (early) version of the language, we will generate error reports at
340 multiple locations, so the use of `hello` will report an error and
341 explain were the value was set, and the addition will report an error
342 and say why numbers are needed. To be able to report locations for
343 errors, each language element will need to record a file location
344 (line and column) and each variable will need to record the language
345 element where its type was set. For now we will assume that each line
346 of an error message indicates one location in the file, and up to 2
347 types. So we provide a `printf`-like function which takes a format, a
348 location (a `struct exec` which has not yet been introduced), and 2
349 types. "`%1`" reports the first type, "`%2`" reports the second. We
350 will need a function to print the location, once we know how that is
351 stored. e As will be explained later, there are sometimes extra rules for
352 type matching and they might affect error messages, we need to pass those
355 As well as type errors, we sometimes need to report problems with
356 tokens, which might be unexpected or might name a type that has not
357 been defined. For these we have `tok_err()` which reports an error
358 with a given token. Each of the error functions sets the flag in the
359 context so indicate that parsing failed.
363 static void fput_loc(struct exec *loc, FILE *f);
364 static void type_err(struct parse_context *c,
365 char *fmt, struct exec *loc,
366 struct type *t1, int rules, struct type *t2);
368 ###### core functions
370 static void type_err(struct parse_context *c,
371 char *fmt, struct exec *loc,
372 struct type *t1, int rules, struct type *t2)
374 fprintf(stderr, "%s:", c->file_name);
375 fput_loc(loc, stderr);
376 for (; *fmt ; fmt++) {
383 case '%': fputc(*fmt, stderr); break; // NOTEST
384 default: fputc('?', stderr); break; // NOTEST
386 type_print(t1, stderr);
389 type_print(t2, stderr);
398 static void tok_err(struct parse_context *c, char *fmt, struct token *t)
400 fprintf(stderr, "%s:%d:%d: %s: %.*s\n", c->file_name, t->line, t->col, fmt,
401 t->txt.len, t->txt.txt);
405 ## Entities: declared and predeclared.
407 There are various "things" that the language and/or the interpreter
408 needs to know about to parse and execute a program. These include
409 types, variables, values, and executable code. These are all lumped
410 together under the term "entities" (calling them "objects" would be
411 confusing) and introduced here. The following section will present the
412 different specific code elements which comprise or manipulate these
417 Executables can be lots of different things. In many cases an
418 executable is just an operation combined with one or two other
419 executables. This allows for expressions and lists etc. Other times an
420 executable is something quite specific like a constant or variable name.
421 So we define a `struct exec` to be a general executable with a type, and
422 a `struct binode` which is a subclass of `exec`, forms a node in a
423 binary tree, and holds an operation. There will be other subclasses,
424 and to access these we need to be able to `cast` the `exec` into the
425 various other types. The first field in any `struct exec` is the type
426 from the `exec_types` enum.
429 #define cast(structname, pointer) ({ \
430 const typeof( ((struct structname *)0)->type) *__mptr = &(pointer)->type; \
431 if (__mptr && *__mptr != X##structname) abort(); \
432 (struct structname *)( (char *)__mptr);})
434 #define new(structname) ({ \
435 struct structname *__ptr = ((struct structname *)calloc(1,sizeof(struct structname))); \
436 __ptr->type = X##structname; \
437 __ptr->line = -1; __ptr->column = -1; \
440 #define new_pos(structname, token) ({ \
441 struct structname *__ptr = ((struct structname *)calloc(1,sizeof(struct structname))); \
442 __ptr->type = X##structname; \
443 __ptr->line = token.line; __ptr->column = token.col; \
452 enum exec_types type;
461 struct exec *left, *right;
466 static int __fput_loc(struct exec *loc, FILE *f)
470 if (loc->line >= 0) {
471 fprintf(f, "%d:%d: ", loc->line, loc->column);
474 if (loc->type == Xbinode)
475 return __fput_loc(cast(binode,loc)->left, f) ||
476 __fput_loc(cast(binode,loc)->right, f); // NOTEST
479 static void fput_loc(struct exec *loc, FILE *f)
481 if (!__fput_loc(loc, f))
482 fprintf(f, "??:??: ");
485 Each different type of `exec` node needs a number of functions defined,
486 a bit like methods. We must be able to free it, print it, analyse it
487 and execute it. Once we have specific `exec` types we will need to
488 parse them too. Let's take this a bit more slowly.
492 The parser generator requires a `free_foo` function for each struct
493 that stores attributes and they will often be `exec`s and subtypes
494 there-of. So we need `free_exec` which can handle all the subtypes,
495 and we need `free_binode`.
499 static void free_binode(struct binode *b)
508 ###### core functions
509 static void free_exec(struct exec *e)
520 static void free_exec(struct exec *e);
522 ###### free exec cases
523 case Xbinode: free_binode(cast(binode, e)); break;
527 Printing an `exec` requires that we know the current indent level for
528 printing line-oriented components. As will become clear later, we
529 also want to know what sort of bracketing to use.
533 static void do_indent(int i, char *str)
540 ###### core functions
541 static void print_binode(struct binode *b, int indent, int bracket)
545 ## print binode cases
549 static void print_exec(struct exec *e, int indent, int bracket)
555 print_binode(cast(binode, e), indent, bracket); break;
560 do_indent(indent, "/* FREE");
561 for (v = e->to_free; v; v = v->next_free) {
562 printf(" %.*s", v->name->name.len, v->name->name.txt);
563 printf("[%d,%d]", v->scope_start, v->scope_end);
564 if (v->frame_pos >= 0)
565 printf("(%d+%d)", v->frame_pos,
566 v->type ? v->type->size:0);
574 static void print_exec(struct exec *e, int indent, int bracket);
578 As discussed, analysis involves propagating type requirements around the
579 program and looking for errors.
581 So `propagate_types` is passed an expected type (being a `struct type`
582 pointer together with some `val_rules` flags) that the `exec` is
583 expected to return, and returns the type that it does return, either
584 of which can be `NULL` signifying "unknown". An `ok` flag is passed
585 by reference. It is set to `0` when an error is found, and `2` when
586 any change is made. If it remains unchanged at `1`, then no more
587 propagation is needed.
591 enum val_rules {Rnolabel = 1<<0, Rboolok = 1<<1, Rnoconstant = 1<<2};
595 if (rules & Rnolabel)
596 fputs(" (labels not permitted)", stderr);
600 static struct type *propagate_types(struct exec *prog, struct parse_context *c, int *ok,
601 struct type *type, int rules);
602 ###### core functions
604 static struct type *__propagate_types(struct exec *prog, struct parse_context *c, int *ok,
605 struct type *type, int rules)
612 switch (prog->type) {
615 struct binode *b = cast(binode, prog);
617 ## propagate binode cases
621 ## propagate exec cases
626 static struct type *propagate_types(struct exec *prog, struct parse_context *c, int *ok,
627 struct type *type, int rules)
629 struct type *ret = __propagate_types(prog, c, ok, type, rules);
638 Interpreting an `exec` doesn't require anything but the `exec`. State
639 is stored in variables and each variable will be directly linked from
640 within the `exec` tree. The exception to this is the `main` function
641 which needs to look at command line arguments. This function will be
642 interpreted separately.
644 Each `exec` can return a value combined with a type in `struct lrval`.
645 The type may be `Tnone` but must be non-NULL. Some `exec`s will return
646 the location of a value, which can be updated, in `lval`. Others will
647 set `lval` to NULL indicating that there is a value of appropriate type
650 ###### core functions
654 struct value rval, *lval;
657 /* If dest is passed, dtype must give the expected type, and
658 * result can go there, in which case type is returned as NULL.
660 static struct lrval _interp_exec(struct parse_context *c, struct exec *e,
661 struct value *dest, struct type *dtype);
663 static struct value interp_exec(struct parse_context *c, struct exec *e,
664 struct type **typeret)
666 struct lrval ret = _interp_exec(c, e, NULL, NULL);
668 if (!ret.type) abort();
672 dup_value(ret.type, ret.lval, &ret.rval);
676 static struct value *linterp_exec(struct parse_context *c, struct exec *e,
677 struct type **typeret)
679 struct lrval ret = _interp_exec(c, e, NULL, NULL);
681 if (!ret.type) abort();
685 free_value(ret.type, &ret.rval);
689 /* dinterp_exec is used when the destination type is certain and
690 * the value has a place to go.
692 static void dinterp_exec(struct parse_context *c, struct exec *e,
693 struct value *dest, struct type *dtype,
696 struct lrval ret = _interp_exec(c, e, dest, dtype);
700 free_value(dtype, dest);
702 dup_value(dtype, ret.lval, dest);
704 memcpy(dest, &ret.rval, dtype->size);
707 static struct lrval _interp_exec(struct parse_context *c, struct exec *e,
708 struct value *dest, struct type *dtype)
710 /* If the result is copied to dest, ret.type is set to NULL */
712 struct value rv = {}, *lrv = NULL;
715 rvtype = ret.type = Tnone;
725 struct binode *b = cast(binode, e);
726 struct value left, right, *lleft;
727 struct type *ltype, *rtype;
728 ltype = rtype = Tnone;
730 ## interp binode cases
732 free_value(ltype, &left);
733 free_value(rtype, &right);
743 ## interp exec cleanup
749 Values come in a wide range of types, with more likely to be added.
750 Each type needs to be able to print its own values (for convenience at
751 least) as well as to compare two values, at least for equality and
752 possibly for order. For now, values might need to be duplicated and
753 freed, though eventually such manipulations will be better integrated
756 Rather than requiring every numeric type to support all numeric
757 operations (add, multiply, etc), we allow types to be able to present
758 as one of a few standard types: integer, float, and fraction. The
759 existence of these conversion functions eventually enable types to
760 determine if they are compatible with other types, though such types
761 have not yet been implemented.
763 Named type are stored in a simple linked list. Objects of each type are
764 "values" which are often passed around by value.
766 There are both explicitly named types, and anonymous types. Anonymous
767 cannot be accessed by name, but are used internally and have a name
768 which might be reported in error messages.
775 ## value union fields
784 void (*init)(struct type *type, struct value *val);
785 void (*prepare_type)(struct parse_context *c, struct type *type, int parse_time);
786 void (*print)(struct type *type, struct value *val, FILE *f);
787 void (*print_type)(struct type *type, FILE *f);
788 int (*cmp_order)(struct type *t1, struct type *t2,
789 struct value *v1, struct value *v2);
790 int (*cmp_eq)(struct type *t1, struct type *t2,
791 struct value *v1, struct value *v2);
792 void (*dup)(struct type *type, struct value *vold, struct value *vnew);
793 void (*free)(struct type *type, struct value *val);
794 void (*free_type)(struct type *t);
795 long long (*to_int)(struct value *v);
796 double (*to_float)(struct value *v);
797 int (*to_mpq)(mpq_t *q, struct value *v);
806 struct type *typelist;
813 static struct type *find_type(struct parse_context *c, struct text s)
815 struct type *t = c->typelist;
817 while (t && (t->anon ||
818 text_cmp(t->name, s) != 0))
823 static struct type *_add_type(struct parse_context *c, struct text s,
824 struct type *proto, int anon)
828 n = calloc(1, sizeof(*n));
832 n->next = c->typelist;
837 static struct type *add_type(struct parse_context *c, struct text s,
840 return _add_type(c, s, proto, 0);
843 static struct type *add_anon_type(struct parse_context *c,
844 struct type *proto, char *name, ...)
850 vasprintf(&t.txt, name, ap);
852 t.len = strlen(name);
853 return _add_type(c, t, proto, 1);
856 static void free_type(struct type *t)
858 /* The type is always a reference to something in the
859 * context, so we don't need to free anything.
863 static void free_value(struct type *type, struct value *v)
867 memset(v, 0x5a, type->size);
871 static void type_print(struct type *type, FILE *f)
874 fputs("*unknown*type*", f); // NOTEST
875 else if (type->name.len && !type->anon)
876 fprintf(f, "%.*s", type->name.len, type->name.txt);
877 else if (type->print_type)
878 type->print_type(type, f);
880 fputs("*invalid*type*", f);
883 static void val_init(struct type *type, struct value *val)
885 if (type && type->init)
886 type->init(type, val);
889 static void dup_value(struct type *type,
890 struct value *vold, struct value *vnew)
892 if (type && type->dup)
893 type->dup(type, vold, vnew);
896 static int value_cmp(struct type *tl, struct type *tr,
897 struct value *left, struct value *right)
899 if (tl && tl->cmp_order)
900 return tl->cmp_order(tl, tr, left, right);
901 if (tl && tl->cmp_eq) // NOTEST
902 return tl->cmp_eq(tl, tr, left, right); // NOTEST
906 static void print_value(struct type *type, struct value *v, FILE *f)
908 if (type && type->print)
909 type->print(type, v, f);
911 fprintf(f, "*Unknown*"); // NOTEST
916 static void free_value(struct type *type, struct value *v);
917 static int type_compat(struct type *require, struct type *have, int rules);
918 static void type_print(struct type *type, FILE *f);
919 static void val_init(struct type *type, struct value *v);
920 static void dup_value(struct type *type,
921 struct value *vold, struct value *vnew);
922 static int value_cmp(struct type *tl, struct type *tr,
923 struct value *left, struct value *right);
924 static void print_value(struct type *type, struct value *v, FILE *f);
926 ###### free context types
928 while (context.typelist) {
929 struct type *t = context.typelist;
931 context.typelist = t->next;
939 Type can be specified for local variables, for fields in a structure,
940 for formal parameters to functions, and possibly elsewhere. Different
941 rules may apply in different contexts. As a minimum, a named type may
942 always be used. Currently the type of a formal parameter can be
943 different from types in other contexts, so we have a separate grammar
949 Type -> IDENTIFIER ${
950 $0 = find_type(c, $1.txt);
953 "error: undefined type", &$1);
960 FormalType -> Type ${ $0 = $<1; }$
961 ## formal type grammar
965 Values of the base types can be numbers, which we represent as
966 multi-precision fractions, strings, Booleans and labels. When
967 analysing the program we also need to allow for places where no value
968 is meaningful (type `Tnone`) and where we don't know what type to
969 expect yet (type is `NULL`).
971 Values are never shared, they are always copied when used, and freed
972 when no longer needed.
974 When propagating type information around the program, we need to
975 determine if two types are compatible, where type `NULL` is compatible
976 with anything. There are two special cases with type compatibility,
977 both related to the Conditional Statement which will be described
978 later. In some cases a Boolean can be accepted as well as some other
979 primary type, and in others any type is acceptable except a label (`Vlabel`).
980 A separate function encoding these cases will simplify some code later.
982 ###### type functions
984 int (*compat)(struct type *this, struct type *other);
988 static int type_compat(struct type *require, struct type *have, int rules)
990 if ((rules & Rboolok) && have == Tbool)
992 if ((rules & Rnolabel) && have == Tlabel)
994 if (!require || !have)
998 return require->compat(require, have);
1000 return require == have;
1005 #include "parse_string.h"
1006 #include "parse_number.h"
1009 myLDLIBS := libnumber.o libstring.o -lgmp
1010 LDLIBS := $(filter-out $(myLDLIBS),$(LDLIBS)) $(myLDLIBS)
1012 ###### type union fields
1013 enum vtype {Vnone, Vstr, Vnum, Vbool, Vlabel} vtype;
1015 ###### value union fields
1021 ###### ast functions
1022 static void _free_value(struct type *type, struct value *v)
1026 switch (type->vtype) {
1028 case Vstr: free(v->str.txt); break;
1029 case Vnum: mpq_clear(v->num); break;
1035 ###### value functions
1037 static void _val_init(struct type *type, struct value *val)
1039 switch(type->vtype) {
1040 case Vnone: // NOTEST
1043 mpq_init(val->num); break;
1045 val->str.txt = malloc(1);
1057 static void _dup_value(struct type *type,
1058 struct value *vold, struct value *vnew)
1060 switch (type->vtype) {
1061 case Vnone: // NOTEST
1064 vnew->label = vold->label;
1067 vnew->bool = vold->bool;
1070 mpq_init(vnew->num);
1071 mpq_set(vnew->num, vold->num);
1074 vnew->str.len = vold->str.len;
1075 vnew->str.txt = malloc(vnew->str.len);
1076 memcpy(vnew->str.txt, vold->str.txt, vnew->str.len);
1081 static int _value_cmp(struct type *tl, struct type *tr,
1082 struct value *left, struct value *right)
1086 return tl - tr; // NOTEST
1087 switch (tl->vtype) {
1088 case Vlabel: cmp = left->label == right->label ? 0 : 1; break;
1089 case Vnum: cmp = mpq_cmp(left->num, right->num); break;
1090 case Vstr: cmp = text_cmp(left->str, right->str); break;
1091 case Vbool: cmp = left->bool - right->bool; break;
1092 case Vnone: cmp = 0; // NOTEST
1097 static void _print_value(struct type *type, struct value *v, FILE *f)
1099 switch (type->vtype) {
1100 case Vnone: // NOTEST
1101 fprintf(f, "*no-value*"); break; // NOTEST
1102 case Vlabel: // NOTEST
1103 fprintf(f, "*label-%p*", v->label); break; // NOTEST
1105 fprintf(f, "%.*s", v->str.len, v->str.txt); break;
1107 fprintf(f, "%s", v->bool ? "True":"False"); break;
1112 mpf_set_q(fl, v->num);
1113 gmp_fprintf(f, "%Fg", fl);
1120 static void _free_value(struct type *type, struct value *v);
1122 static struct type base_prototype = {
1124 .print = _print_value,
1125 .cmp_order = _value_cmp,
1126 .cmp_eq = _value_cmp,
1128 .free = _free_value,
1131 static struct type *Tbool, *Tstr, *Tnum, *Tnone, *Tlabel;
1133 ###### ast functions
1134 static struct type *add_base_type(struct parse_context *c, char *n,
1135 enum vtype vt, int size)
1137 struct text txt = { n, strlen(n) };
1140 t = add_type(c, txt, &base_prototype);
1143 t->align = size > sizeof(void*) ? sizeof(void*) : size;
1144 if (t->size & (t->align - 1))
1145 t->size = (t->size | (t->align - 1)) + 1; // NOTEST
1149 ###### context initialization
1151 Tbool = add_base_type(&context, "Boolean", Vbool, sizeof(char));
1152 Tstr = add_base_type(&context, "string", Vstr, sizeof(struct text));
1153 Tnum = add_base_type(&context, "number", Vnum, sizeof(mpq_t));
1154 Tnone = add_base_type(&context, "none", Vnone, 0);
1155 Tlabel = add_base_type(&context, "label", Vlabel, sizeof(void*));
1159 We have already met values as separate objects. When manifest constants
1160 appear in the program text, that must result in an executable which has
1161 a constant value. So the `val` structure embeds a value in an
1174 ###### ast functions
1175 struct val *new_val(struct type *T, struct token tk)
1177 struct val *v = new_pos(val, tk);
1188 $0 = new_val(Tbool, $1);
1192 $0 = new_val(Tbool, $1);
1197 $0 = new_val(Tnum, $1);
1198 if (number_parse($0->val.num, tail, $1.txt) == 0)
1199 mpq_init($0->val.num); // UNTESTED
1201 tok_err(c, "error: unsupported number suffix",
1206 $0 = new_val(Tstr, $1);
1207 string_parse(&$1, '\\', &$0->val.str, tail);
1209 tok_err(c, "error: unsupported string suffix",
1214 $0 = new_val(Tstr, $1);
1215 string_parse(&$1, '\\', &$0->val.str, tail);
1217 tok_err(c, "error: unsupported string suffix",
1221 ###### print exec cases
1224 struct val *v = cast(val, e);
1225 if (v->vtype == Tstr)
1227 print_value(v->vtype, &v->val, stdout);
1228 if (v->vtype == Tstr)
1233 ###### propagate exec cases
1236 struct val *val = cast(val, prog);
1237 if (!type_compat(type, val->vtype, rules))
1238 type_err(c, "error: expected %1%r found %2",
1239 prog, type, rules, val->vtype);
1243 ###### interp exec cases
1245 rvtype = cast(val, e)->vtype;
1246 dup_value(rvtype, &cast(val, e)->val, &rv);
1249 ###### ast functions
1250 static void free_val(struct val *v)
1253 free_value(v->vtype, &v->val);
1257 ###### free exec cases
1258 case Xval: free_val(cast(val, e)); break;
1260 ###### ast functions
1261 // Move all nodes from 'b' to 'rv', reversing their order.
1262 // In 'b' 'left' is a list, and 'right' is the last node.
1263 // In 'rv', left' is the first node and 'right' is a list.
1264 static struct binode *reorder_bilist(struct binode *b)
1266 struct binode *rv = NULL;
1269 struct exec *t = b->right;
1273 b = cast(binode, b->left);
1283 Variables are scoped named values. We store the names in a linked list
1284 of "bindings" sorted in lexical order, and use sequential search and
1291 struct binding *next; // in lexical order
1295 This linked list is stored in the parse context so that "reduce"
1296 functions can find or add variables, and so the analysis phase can
1297 ensure that every variable gets a type.
1299 ###### parse context
1301 struct binding *varlist; // In lexical order
1303 ###### ast functions
1305 static struct binding *find_binding(struct parse_context *c, struct text s)
1307 struct binding **l = &c->varlist;
1312 (cmp = text_cmp((*l)->name, s)) < 0)
1316 n = calloc(1, sizeof(*n));
1323 Each name can be linked to multiple variables defined in different
1324 scopes. Each scope starts where the name is declared and continues
1325 until the end of the containing code block. Scopes of a given name
1326 cannot nest, so a declaration while a name is in-scope is an error.
1328 ###### binding fields
1329 struct variable *var;
1333 struct variable *previous;
1335 struct binding *name;
1336 struct exec *where_decl;// where name was declared
1337 struct exec *where_set; // where type was set
1341 When a scope closes, the values of the variables might need to be freed.
1342 This happens in the context of some `struct exec` and each `exec` will
1343 need to know which variables need to be freed when it completes.
1346 struct variable *to_free;
1348 ####### variable fields
1349 struct exec *cleanup_exec;
1350 struct variable *next_free;
1352 ####### interp exec cleanup
1355 for (v = e->to_free; v; v = v->next_free) {
1356 struct value *val = var_value(c, v);
1357 free_value(v->type, val);
1361 ###### ast functions
1362 static void variable_unlink_exec(struct variable *v)
1364 struct variable **vp;
1365 if (!v->cleanup_exec)
1367 for (vp = &v->cleanup_exec->to_free;
1368 *vp; vp = &(*vp)->next_free) {
1372 v->cleanup_exec = NULL;
1377 While the naming seems strange, we include local constants in the
1378 definition of variables. A name declared `var := value` can
1379 subsequently be changed, but a name declared `var ::= value` cannot -
1382 ###### variable fields
1385 Scopes in parallel branches can be partially merged. More
1386 specifically, if a given name is declared in both branches of an
1387 if/else then its scope is a candidate for merging. Similarly if
1388 every branch of an exhaustive switch (e.g. has an "else" clause)
1389 declares a given name, then the scopes from the branches are
1390 candidates for merging.
1392 Note that names declared inside a loop (which is only parallel to
1393 itself) are never visible after the loop. Similarly names defined in
1394 scopes which are not parallel, such as those started by `for` and
1395 `switch`, are never visible after the scope. Only variables defined in
1396 both `then` and `else` (including the implicit then after an `if`, and
1397 excluding `then` used with `for`) and in all `case`s and `else` of a
1398 `switch` or `while` can be visible beyond the `if`/`switch`/`while`.
1400 Labels, which are a bit like variables, follow different rules.
1401 Labels are not explicitly declared, but if an undeclared name appears
1402 in a context where a label is legal, that effectively declares the
1403 name as a label. The declaration remains in force (or in scope) at
1404 least to the end of the immediately containing block and conditionally
1405 in any larger containing block which does not declare the name in some
1406 other way. Importantly, the conditional scope extension happens even
1407 if the label is only used in one parallel branch of a conditional --
1408 when used in one branch it is treated as having been declared in all
1411 Merge candidates are tentatively visible beyond the end of the
1412 branching statement which creates them. If the name is used, the
1413 merge is affirmed and they become a single variable visible at the
1414 outer layer. If not - if it is redeclared first - the merge lapses.
1416 To track scopes we have an extra stack, implemented as a linked list,
1417 which roughly parallels the parse stack and which is used exclusively
1418 for scoping. When a new scope is opened, a new frame is pushed and
1419 the child-count of the parent frame is incremented. This child-count
1420 is used to distinguish between the first of a set of parallel scopes,
1421 in which declared variables must not be in scope, and subsequent
1422 branches, whether they may already be conditionally scoped.
1424 We need a total ordering of scopes so we can easily compare to variables
1425 to see if they are concurrently in scope. To achieve this we record a
1426 `scope_count` which is actually a count of both beginnings and endings
1427 of scopes. Then each variable has a record of the scope count where it
1428 enters scope, and where it leaves.
1430 To push a new frame *before* any code in the frame is parsed, we need a
1431 grammar reduction. This is most easily achieved with a grammar
1432 element which derives the empty string, and creates the new scope when
1433 it is recognised. This can be placed, for example, between a keyword
1434 like "if" and the code following it.
1438 struct scope *parent;
1442 ###### parse context
1445 struct scope *scope_stack;
1447 ###### variable fields
1448 int scope_start, scope_end;
1450 ###### ast functions
1451 static void scope_pop(struct parse_context *c)
1453 struct scope *s = c->scope_stack;
1455 c->scope_stack = s->parent;
1457 c->scope_depth -= 1;
1458 c->scope_count += 1;
1461 static void scope_push(struct parse_context *c)
1463 struct scope *s = calloc(1, sizeof(*s));
1465 c->scope_stack->child_count += 1;
1466 s->parent = c->scope_stack;
1468 c->scope_depth += 1;
1469 c->scope_count += 1;
1475 OpenScope -> ${ scope_push(c); }$
1477 Each variable records a scope depth and is in one of four states:
1479 - "in scope". This is the case between the declaration of the
1480 variable and the end of the containing block, and also between
1481 the usage with affirms a merge and the end of that block.
1483 The scope depth is not greater than the current parse context scope
1484 nest depth. When the block of that depth closes, the state will
1485 change. To achieve this, all "in scope" variables are linked
1486 together as a stack in nesting order.
1488 - "pending". The "in scope" block has closed, but other parallel
1489 scopes are still being processed. So far, every parallel block at
1490 the same level that has closed has declared the name.
1492 The scope depth is the depth of the last parallel block that
1493 enclosed the declaration, and that has closed.
1495 - "conditionally in scope". The "in scope" block and all parallel
1496 scopes have closed, and no further mention of the name has been seen.
1497 This state includes a secondary nest depth (`min_depth`) which records
1498 the outermost scope seen since the variable became conditionally in
1499 scope. If a use of the name is found, the variable becomes "in scope"
1500 and that secondary depth becomes the recorded scope depth. If the
1501 name is declared as a new variable, the old variable becomes "out of
1502 scope" and the recorded scope depth stays unchanged.
1504 - "out of scope". The variable is neither in scope nor conditionally
1505 in scope. It is permanently out of scope now and can be removed from
1506 the "in scope" stack. When a variable becomes out-of-scope it is
1507 moved to a separate list (`out_scope`) of variables which have fully
1508 known scope. This will be used at the end of each function to assign
1509 each variable a place in the stack frame.
1511 ###### variable fields
1512 int depth, min_depth;
1513 enum { OutScope, PendingScope, CondScope, InScope } scope;
1514 struct variable *in_scope;
1516 ###### parse context
1518 struct variable *in_scope;
1519 struct variable *out_scope;
1521 All variables with the same name are linked together using the
1522 'previous' link. Those variable that have been affirmatively merged all
1523 have a 'merged' pointer that points to one primary variable - the most
1524 recently declared instance. When merging variables, we need to also
1525 adjust the 'merged' pointer on any other variables that had previously
1526 been merged with the one that will no longer be primary.
1528 A variable that is no longer the most recent instance of a name may
1529 still have "pending" scope, if it might still be merged with most
1530 recent instance. These variables don't really belong in the
1531 "in_scope" list, but are not immediately removed when a new instance
1532 is found. Instead, they are detected and ignored when considering the
1533 list of in_scope names.
1535 The storage of the value of a variable will be described later. For now
1536 we just need to know that when a variable goes out of scope, it might
1537 need to be freed. For this we need to be able to find it, so assume that
1538 `var_value()` will provide that.
1540 ###### variable fields
1541 struct variable *merged;
1543 ###### ast functions
1545 static void variable_merge(struct variable *primary, struct variable *secondary)
1549 primary = primary->merged;
1551 for (v = primary->previous; v; v=v->previous)
1552 if (v == secondary || v == secondary->merged ||
1553 v->merged == secondary ||
1554 v->merged == secondary->merged) {
1555 v->scope = OutScope;
1556 v->merged = primary;
1557 if (v->scope_start < primary->scope_start)
1558 primary->scope_start = v->scope_start;
1559 if (v->scope_end > primary->scope_end)
1560 primary->scope_end = v->scope_end; // NOTEST
1561 variable_unlink_exec(v);
1565 ###### forward decls
1566 static struct value *var_value(struct parse_context *c, struct variable *v);
1568 ###### free global vars
1570 while (context.varlist) {
1571 struct binding *b = context.varlist;
1572 struct variable *v = b->var;
1573 context.varlist = b->next;
1576 struct variable *next = v->previous;
1579 free_value(v->type, var_value(&context, v));
1581 // This is a global constant
1582 free_exec(v->where_decl);
1589 #### Manipulating Bindings
1591 When a name is conditionally visible, a new declaration discards the old
1592 binding - the condition lapses. Similarly when we reach the end of a
1593 function (outermost non-global scope) any conditional scope must lapse.
1594 Conversely a usage of the name affirms the visibility and extends it to
1595 the end of the containing block - i.e. the block that contains both the
1596 original declaration and the latest usage. This is determined from
1597 `min_depth`. When a conditionally visible variable gets affirmed like
1598 this, it is also merged with other conditionally visible variables with
1601 When we parse a variable declaration we either report an error if the
1602 name is currently bound, or create a new variable at the current nest
1603 depth if the name is unbound or bound to a conditionally scoped or
1604 pending-scope variable. If the previous variable was conditionally
1605 scoped, it and its homonyms becomes out-of-scope.
1607 When we parse a variable reference (including non-declarative assignment
1608 "foo = bar") we report an error if the name is not bound or is bound to
1609 a pending-scope variable; update the scope if the name is bound to a
1610 conditionally scoped variable; or just proceed normally if the named
1611 variable is in scope.
1613 When we exit a scope, any variables bound at this level are either
1614 marked out of scope or pending-scoped, depending on whether the scope
1615 was sequential or parallel. Here a "parallel" scope means the "then"
1616 or "else" part of a conditional, or any "case" or "else" branch of a
1617 switch. Other scopes are "sequential".
1619 When exiting a parallel scope we check if there are any variables that
1620 were previously pending and are still visible. If there are, then
1621 they weren't redeclared in the most recent scope, so they cannot be
1622 merged and must become out-of-scope. If it is not the first of
1623 parallel scopes (based on `child_count`), we check that there was a
1624 previous binding that is still pending-scope. If there isn't, the new
1625 variable must now be out-of-scope.
1627 When exiting a sequential scope that immediately enclosed parallel
1628 scopes, we need to resolve any pending-scope variables. If there was
1629 no `else` clause, and we cannot determine that the `switch` was exhaustive,
1630 we need to mark all pending-scope variable as out-of-scope. Otherwise
1631 all pending-scope variables become conditionally scoped.
1634 enum closetype { CloseSequential, CloseFunction, CloseParallel, CloseElse };
1636 ###### ast functions
1638 static struct variable *var_decl(struct parse_context *c, struct text s)
1640 struct binding *b = find_binding(c, s);
1641 struct variable *v = b->var;
1643 switch (v ? v->scope : OutScope) {
1645 /* Caller will report the error */
1649 v && v->scope == CondScope;
1651 v->scope = OutScope;
1655 v = calloc(1, sizeof(*v));
1656 v->previous = b->var;
1660 v->min_depth = v->depth = c->scope_depth;
1662 v->in_scope = c->in_scope;
1663 v->scope_start = c->scope_count;
1669 static struct variable *var_ref(struct parse_context *c, struct text s)
1671 struct binding *b = find_binding(c, s);
1672 struct variable *v = b->var;
1673 struct variable *v2;
1675 switch (v ? v->scope : OutScope) {
1678 /* Caller will report the error */
1681 /* All CondScope variables of this name need to be merged
1682 * and become InScope
1684 v->depth = v->min_depth;
1686 for (v2 = v->previous;
1687 v2 && v2->scope == CondScope;
1689 variable_merge(v, v2);
1697 static int var_refile(struct parse_context *c, struct variable *v)
1699 /* Variable just went out of scope. Add it to the out_scope
1700 * list, sorted by ->scope_start
1702 struct variable **vp = &c->out_scope;
1703 while ((*vp) && (*vp)->scope_start < v->scope_start)
1704 vp = &(*vp)->in_scope;
1710 static void var_block_close(struct parse_context *c, enum closetype ct,
1713 /* Close off all variables that are in_scope.
1714 * Some variables in c->scope may already be not-in-scope,
1715 * such as when a PendingScope variable is hidden by a new
1716 * variable with the same name.
1717 * So we check for v->name->var != v and drop them.
1718 * If we choose to make a variable OutScope, we drop it
1721 struct variable *v, **vp, *v2;
1724 for (vp = &c->in_scope;
1725 (v = *vp) && v->min_depth > c->scope_depth;
1726 (v->scope == OutScope || v->name->var != v)
1727 ? (*vp = v->in_scope, var_refile(c, v))
1728 : ( vp = &v->in_scope, 0)) {
1729 v->min_depth = c->scope_depth;
1730 if (v->name->var != v)
1731 /* This is still in scope, but we haven't just
1735 v->min_depth = c->scope_depth;
1736 if (v->scope == InScope)
1737 v->scope_end = c->scope_count;
1738 if (v->scope == InScope && e && !v->global) {
1739 /* This variable gets cleaned up when 'e' finishes */
1740 variable_unlink_exec(v);
1741 v->cleanup_exec = e;
1742 v->next_free = e->to_free;
1747 case CloseParallel: /* handle PendingScope */
1751 if (c->scope_stack->child_count == 1)
1752 /* first among parallel branches */
1753 v->scope = PendingScope;
1754 else if (v->previous &&
1755 v->previous->scope == PendingScope)
1756 /* all previous branches used name */
1757 v->scope = PendingScope;
1758 else if (v->type == Tlabel)
1759 /* Labels remain pending even when not used */
1760 v->scope = PendingScope; // UNTESTED
1762 v->scope = OutScope;
1763 if (ct == CloseElse) {
1764 /* All Pending variables with this name
1765 * are now Conditional */
1767 v2 && v2->scope == PendingScope;
1769 v2->scope = CondScope;
1773 /* Not possible as it would require
1774 * parallel scope to be nested immediately
1775 * in a parallel scope, and that never
1779 /* Not possible as we already tested for
1786 if (v->scope == CondScope)
1787 /* Condition cannot continue past end of function */
1790 case CloseSequential:
1791 if (v->type == Tlabel)
1792 v->scope = PendingScope;
1795 v->scope = OutScope;
1798 /* There was no 'else', so we can only become
1799 * conditional if we know the cases were exhaustive,
1800 * and that doesn't mean anything yet.
1801 * So only labels become conditional..
1804 v2 && v2->scope == PendingScope;
1806 if (v2->type == Tlabel)
1807 v2->scope = CondScope;
1809 v2->scope = OutScope;
1812 case OutScope: break;
1821 The value of a variable is store separately from the variable, on an
1822 analogue of a stack frame. There are (currently) two frames that can be
1823 active. A global frame which currently only stores constants, and a
1824 stacked frame which stores local variables. Each variable knows if it
1825 is global or not, and what its index into the frame is.
1827 Values in the global frame are known immediately they are relevant, so
1828 the frame needs to be reallocated as it grows so it can store those
1829 values. The local frame doesn't get values until the interpreted phase
1830 is started, so there is no need to allocate until the size is known.
1832 We initialize the `frame_pos` to an impossible value, so that we can
1833 tell if it was set or not later.
1835 ###### variable fields
1839 ###### variable init
1842 ###### parse context
1844 short global_size, global_alloc;
1846 void *global, *local;
1848 ###### ast functions
1850 static struct value *var_value(struct parse_context *c, struct variable *v)
1853 if (!c->local || !v->type)
1854 return NULL; // NOTEST
1855 if (v->frame_pos + v->type->size > c->local_size) {
1856 printf("INVALID frame_pos\n"); // NOTEST
1859 return c->local + v->frame_pos;
1861 if (c->global_size > c->global_alloc) {
1862 int old = c->global_alloc;
1863 c->global_alloc = (c->global_size | 1023) + 1024;
1864 c->global = realloc(c->global, c->global_alloc);
1865 memset(c->global + old, 0, c->global_alloc - old);
1867 return c->global + v->frame_pos;
1870 static struct value *global_alloc(struct parse_context *c, struct type *t,
1871 struct variable *v, struct value *init)
1874 struct variable scratch;
1876 if (t->prepare_type)
1877 t->prepare_type(c, t, 1); // NOTEST
1879 if (c->global_size & (t->align - 1))
1880 c->global_size = (c->global_size + t->align) & ~(t->align-1);
1885 v->frame_pos = c->global_size;
1887 c->global_size += v->type->size;
1888 ret = var_value(c, v);
1890 memcpy(ret, init, t->size);
1896 As global values are found -- struct field initializers, labels etc --
1897 `global_alloc()` is called to record the value in the global frame.
1899 When the program is fully parsed, each function is analysed, we need to
1900 walk the list of variables local to that function and assign them an
1901 offset in the stack frame. For this we have `scope_finalize()`.
1903 We keep the stack from dense by re-using space for between variables
1904 that are not in scope at the same time. The `out_scope` list is sorted
1905 by `scope_start` and as we process a varible, we move it to an FIFO
1906 stack. For each variable we consider, we first discard any from the
1907 stack anything that went out of scope before the new variable came in.
1908 Then we place the new variable just after the one at the top of the
1911 ###### ast functions
1913 static void scope_finalize(struct parse_context *c, struct type *ft)
1915 int size = ft->function.local_size;
1916 struct variable *next = ft->function.scope;
1917 struct variable *done = NULL;
1920 struct variable *v = next;
1921 struct type *t = v->type;
1928 if (v->frame_pos >= 0)
1930 while (done && done->scope_end < v->scope_start)
1931 done = done->in_scope;
1933 pos = done->frame_pos + done->type->size;
1935 pos = ft->function.local_size;
1936 if (pos & (t->align - 1))
1937 pos = (pos + t->align) & ~(t->align-1);
1939 if (size < pos + v->type->size)
1940 size = pos + v->type->size;
1944 c->out_scope = NULL;
1945 ft->function.local_size = size;
1948 ###### free context storage
1949 free(context.global);
1951 #### Variables as executables
1953 Just as we used a `val` to wrap a value into an `exec`, we similarly
1954 need a `var` to wrap a `variable` into an exec. While each `val`
1955 contained a copy of the value, each `var` holds a link to the variable
1956 because it really is the same variable no matter where it appears.
1957 When a variable is used, we need to remember to follow the `->merged`
1958 link to find the primary instance.
1960 When a variable is declared, it may or may not be given an explicit
1961 type. We need to record which so that we can report the parsed code
1970 struct variable *var;
1973 ###### variable fields
1981 VariableDecl -> IDENTIFIER : ${ {
1982 struct variable *v = var_decl(c, $1.txt);
1983 $0 = new_pos(var, $1);
1988 v = var_ref(c, $1.txt);
1990 type_err(c, "error: variable '%v' redeclared",
1992 type_err(c, "info: this is where '%v' was first declared",
1993 v->where_decl, NULL, 0, NULL);
1996 | IDENTIFIER :: ${ {
1997 struct variable *v = var_decl(c, $1.txt);
1998 $0 = new_pos(var, $1);
2004 v = var_ref(c, $1.txt);
2006 type_err(c, "error: variable '%v' redeclared",
2008 type_err(c, "info: this is where '%v' was first declared",
2009 v->where_decl, NULL, 0, NULL);
2012 | IDENTIFIER : Type ${ {
2013 struct variable *v = var_decl(c, $1.txt);
2014 $0 = new_pos(var, $1);
2020 v->explicit_type = 1;
2022 v = var_ref(c, $1.txt);
2024 type_err(c, "error: variable '%v' redeclared",
2026 type_err(c, "info: this is where '%v' was first declared",
2027 v->where_decl, NULL, 0, NULL);
2030 | IDENTIFIER :: Type ${ {
2031 struct variable *v = var_decl(c, $1.txt);
2032 $0 = new_pos(var, $1);
2039 v->explicit_type = 1;
2041 v = var_ref(c, $1.txt);
2043 type_err(c, "error: variable '%v' redeclared",
2045 type_err(c, "info: this is where '%v' was first declared",
2046 v->where_decl, NULL, 0, NULL);
2051 Variable -> IDENTIFIER ${ {
2052 struct variable *v = var_ref(c, $1.txt);
2053 $0 = new_pos(var, $1);
2055 /* This might be a label - allocate a var just in case */
2056 v = var_decl(c, $1.txt);
2063 cast(var, $0)->var = v;
2066 ###### print exec cases
2069 struct var *v = cast(var, e);
2071 struct binding *b = v->var->name;
2072 printf("%.*s", b->name.len, b->name.txt);
2079 if (loc && loc->type == Xvar) {
2080 struct var *v = cast(var, loc);
2082 struct binding *b = v->var->name;
2083 fprintf(stderr, "%.*s", b->name.len, b->name.txt);
2085 fputs("???", stderr); // NOTEST
2087 fputs("NOTVAR", stderr);
2090 ###### propagate exec cases
2094 struct var *var = cast(var, prog);
2095 struct variable *v = var->var;
2097 type_err(c, "%d:BUG: no variable!!", prog, NULL, 0, NULL); // NOTEST
2098 return Tnone; // NOTEST
2101 if (v->constant && (rules & Rnoconstant)) {
2102 type_err(c, "error: Cannot assign to a constant: %v",
2103 prog, NULL, 0, NULL);
2104 type_err(c, "info: name was defined as a constant here",
2105 v->where_decl, NULL, 0, NULL);
2108 if (v->type == Tnone && v->where_decl == prog)
2109 type_err(c, "error: variable used but not declared: %v",
2110 prog, NULL, 0, NULL);
2111 if (v->type == NULL) {
2112 if (type && *ok != 0) {
2114 v->where_set = prog;
2119 if (!type_compat(type, v->type, rules)) {
2120 type_err(c, "error: expected %1%r but variable '%v' is %2", prog,
2121 type, rules, v->type);
2122 type_err(c, "info: this is where '%v' was set to %1", v->where_set,
2123 v->type, rules, NULL);
2130 ###### interp exec cases
2133 struct var *var = cast(var, e);
2134 struct variable *v = var->var;
2137 lrv = var_value(c, v);
2142 ###### ast functions
2144 static void free_var(struct var *v)
2149 ###### free exec cases
2150 case Xvar: free_var(cast(var, e)); break;
2155 Now that we have the shape of the interpreter in place we can add some
2156 complex types and connected them in to the data structures and the
2157 different phases of parse, analyse, print, interpret.
2159 Being "complex" the language will naturally have syntax to access
2160 specifics of objects of these types. These will fit into the grammar as
2161 "Terms" which are the things that are combined with various operators to
2162 form "Expression". Where a Term is formed by some operation on another
2163 Term, the subordinate Term will always come first, so for example a
2164 member of an array will be expressed as the Term for the array followed
2165 by an index in square brackets. The strict rule of using postfix
2166 operations makes precedence irrelevant within terms. To provide a place
2167 to put the grammar for each terms of each type, we will start out by
2168 introducing the "Term" grammar production, with contains at least a
2169 simple "Value" (to be explained later).
2173 Term -> Value ${ $0 = $<1; }$
2174 | Variable ${ $0 = $<1; }$
2177 Thus far the complex types we have are arrays and structs.
2181 Arrays can be declared by giving a size and a type, as `[size]type' so
2182 `freq:[26]number` declares `freq` to be an array of 26 numbers. The
2183 size can be either a literal number, or a named constant. Some day an
2184 arbitrary expression will be supported.
2186 As a formal parameter to a function, the array can be declared with a
2187 new variable as the size: `name:[size::number]string`. The `size`
2188 variable is set to the size of the array and must be a constant. As
2189 `number` is the only supported type, it can be left out:
2190 `name:[size::]string`.
2192 Arrays cannot be assigned. When pointers are introduced we will also
2193 introduce array slices which can refer to part or all of an array -
2194 the assignment syntax will create a slice. For now, an array can only
2195 ever be referenced by the name it is declared with. It is likely that
2196 a "`copy`" primitive will eventually be define which can be used to
2197 make a copy of an array with controllable recursive depth.
2199 For now we have two sorts of array, those with fixed size either because
2200 it is given as a literal number or because it is a struct member (which
2201 cannot have a runtime-changing size), and those with a size that is
2202 determined at runtime - local variables with a const size. The former
2203 have their size calculated at parse time, the latter at run time.
2205 For the latter type, the `size` field of the type is the size of a
2206 pointer, and the array is reallocated every time it comes into scope.
2208 We differentiate struct fields with a const size from local variables
2209 with a const size by whether they are prepared at parse time or not.
2211 ###### type union fields
2214 int unspec; // size is unspecified - vsize must be set.
2217 struct variable *vsize;
2218 struct type *member;
2221 ###### value union fields
2222 void *array; // used if not static_size
2224 ###### value functions
2226 static void array_prepare_type(struct parse_context *c, struct type *type,
2229 struct value *vsize;
2231 if (!type->array.vsize || type->array.static_size)
2234 vsize = var_value(c, type->array.vsize);
2236 mpz_tdiv_q(q, mpq_numref(vsize->num), mpq_denref(vsize->num));
2237 type->array.size = mpz_get_si(q);
2241 type->array.static_size = 1;
2242 type->size = type->array.size * type->array.member->size;
2243 type->align = type->array.member->align;
2247 static void array_init(struct type *type, struct value *val)
2250 void *ptr = val->ptr;
2254 if (!type->array.static_size) {
2255 val->array = calloc(type->array.size,
2256 type->array.member->size);
2259 for (i = 0; i < type->array.size; i++) {
2261 v = (void*)ptr + i * type->array.member->size;
2262 val_init(type->array.member, v);
2266 static void array_free(struct type *type, struct value *val)
2269 void *ptr = val->ptr;
2271 if (!type->array.static_size)
2273 for (i = 0; i < type->array.size; i++) {
2275 v = (void*)ptr + i * type->array.member->size;
2276 free_value(type->array.member, v);
2278 if (!type->array.static_size)
2282 static int array_compat(struct type *require, struct type *have)
2284 if (have->compat != require->compat)
2286 /* Both are arrays, so we can look at details */
2287 if (!type_compat(require->array.member, have->array.member, 0))
2289 if (have->array.unspec && require->array.unspec) {
2290 if (have->array.vsize && require->array.vsize &&
2291 have->array.vsize != require->array.vsize) // UNTESTED
2292 /* sizes might not be the same */
2293 return 0; // UNTESTED
2296 if (have->array.unspec || require->array.unspec)
2297 return 1; // UNTESTED
2298 if (require->array.vsize == NULL && have->array.vsize == NULL)
2299 return require->array.size == have->array.size;
2301 return require->array.vsize == have->array.vsize; // UNTESTED
2304 static void array_print_type(struct type *type, FILE *f)
2307 if (type->array.vsize) {
2308 struct binding *b = type->array.vsize->name;
2309 fprintf(f, "%.*s%s]", b->name.len, b->name.txt,
2310 type->array.unspec ? "::" : "");
2311 } else if (type->array.size)
2312 fprintf(f, "%d]", type->array.size);
2315 type_print(type->array.member, f);
2318 static struct type array_prototype = {
2320 .prepare_type = array_prepare_type,
2321 .print_type = array_print_type,
2322 .compat = array_compat,
2324 .size = sizeof(void*),
2325 .align = sizeof(void*),
2328 ###### declare terminals
2333 | [ NUMBER ] Type ${ {
2339 if (number_parse(num, tail, $2.txt) == 0)
2340 tok_err(c, "error: unrecognised number", &$2);
2342 tok_err(c, "error: unsupported number suffix", &$2);
2345 elements = mpz_get_ui(mpq_numref(num));
2346 if (mpz_cmp_ui(mpq_denref(num), 1) != 0) {
2347 tok_err(c, "error: array size must be an integer",
2349 } else if (mpz_cmp_ui(mpq_numref(num), 1UL << 30) >= 0)
2350 tok_err(c, "error: array size is too large",
2355 $0 = t = add_anon_type(c, &array_prototype, "array[%d]", elements );
2356 t->array.size = elements;
2357 t->array.member = $<4;
2358 t->array.vsize = NULL;
2359 t->array.static_size = 1;
2360 t->size = t->array.size * t->array.member->size;
2361 t->align = t->array.member->align;
2364 | [ IDENTIFIER ] Type ${ {
2365 struct variable *v = var_ref(c, $2.txt);
2368 tok_err(c, "error: name undeclared", &$2);
2369 else if (!v->constant)
2370 tok_err(c, "error: array size must be a constant", &$2);
2372 $0 = add_anon_type(c, &array_prototype, "array[%.*s]", $2.txt.len, $2.txt.txt);
2373 $0->array.member = $<4;
2375 $0->array.vsize = v;
2380 OptType -> Type ${ $0 = $<1; }$
2383 ###### formal type grammar
2385 | [ IDENTIFIER :: OptType ] Type ${ {
2386 struct variable *v = var_decl(c, $ID.txt);
2392 $0 = add_anon_type(c, &array_prototype, "array[var]");
2393 $0->array.member = $<6;
2395 $0->array.unspec = 1;
2396 $0->array.vsize = v;
2404 | Term [ Expression ] ${ {
2405 struct binode *b = new(binode);
2412 ###### print binode cases
2414 print_exec(b->left, -1, bracket);
2416 print_exec(b->right, -1, bracket);
2420 ###### propagate binode cases
2422 /* left must be an array, right must be a number,
2423 * result is the member type of the array
2425 propagate_types(b->right, c, ok, Tnum, 0);
2426 t = propagate_types(b->left, c, ok, NULL, rules & Rnoconstant);
2427 if (!t || t->compat != array_compat) {
2428 type_err(c, "error: %1 cannot be indexed", prog, t, 0, NULL);
2431 if (!type_compat(type, t->array.member, rules)) {
2432 type_err(c, "error: have %1 but need %2", prog,
2433 t->array.member, rules, type);
2435 return t->array.member;
2439 ###### interp binode cases
2445 lleft = linterp_exec(c, b->left, <ype);
2446 right = interp_exec(c, b->right, &rtype);
2448 mpz_tdiv_q(q, mpq_numref(right.num), mpq_denref(right.num));
2452 if (ltype->array.static_size)
2455 ptr = *(void**)lleft;
2456 rvtype = ltype->array.member;
2457 if (i >= 0 && i < ltype->array.size)
2458 lrv = ptr + i * rvtype->size;
2460 val_init(ltype->array.member, &rv); // UNSAFE
2467 A `struct` is a data-type that contains one or more other data-types.
2468 It differs from an array in that each member can be of a different
2469 type, and they are accessed by name rather than by number. Thus you
2470 cannot choose an element by calculation, you need to know what you
2473 The language makes no promises about how a given structure will be
2474 stored in memory - it is free to rearrange fields to suit whatever
2475 criteria seems important.
2477 Structs are declared separately from program code - they cannot be
2478 declared in-line in a variable declaration like arrays can. A struct
2479 is given a name and this name is used to identify the type - the name
2480 is not prefixed by the word `struct` as it would be in C.
2482 Structs are only treated as the same if they have the same name.
2483 Simply having the same fields in the same order is not enough. This
2484 might change once we can create structure initializers from a list of
2487 Each component datum is identified much like a variable is declared,
2488 with a name, one or two colons, and a type. The type cannot be omitted
2489 as there is no opportunity to deduce the type from usage. An initial
2490 value can be given following an equals sign, so
2492 ##### Example: a struct type
2498 would declare a type called "complex" which has two number fields,
2499 each initialised to zero.
2501 Struct will need to be declared separately from the code that uses
2502 them, so we will need to be able to print out the declaration of a
2503 struct when reprinting the whole program. So a `print_type_decl` type
2504 function will be needed.
2506 ###### type union fields
2518 ###### type functions
2519 void (*print_type_decl)(struct type *type, FILE *f);
2521 ###### value functions
2523 static void structure_init(struct type *type, struct value *val)
2527 for (i = 0; i < type->structure.nfields; i++) {
2529 v = (void*) val->ptr + type->structure.fields[i].offset;
2530 if (type->structure.fields[i].init)
2531 dup_value(type->structure.fields[i].type,
2532 type->structure.fields[i].init,
2535 val_init(type->structure.fields[i].type, v);
2539 static void structure_free(struct type *type, struct value *val)
2543 for (i = 0; i < type->structure.nfields; i++) {
2545 v = (void*)val->ptr + type->structure.fields[i].offset;
2546 free_value(type->structure.fields[i].type, v);
2550 static void structure_free_type(struct type *t)
2553 for (i = 0; i < t->structure.nfields; i++)
2554 if (t->structure.fields[i].init) {
2555 free_value(t->structure.fields[i].type,
2556 t->structure.fields[i].init);
2558 free(t->structure.fields);
2561 static struct type structure_prototype = {
2562 .init = structure_init,
2563 .free = structure_free,
2564 .free_type = structure_free_type,
2565 .print_type_decl = structure_print_type,
2579 ###### free exec cases
2581 free_exec(cast(fieldref, e)->left);
2585 ###### declare terminals
2590 | Term . IDENTIFIER ${ {
2591 struct fieldref *fr = new_pos(fieldref, $2);
2598 ###### print exec cases
2602 struct fieldref *f = cast(fieldref, e);
2603 print_exec(f->left, -1, bracket);
2604 printf(".%.*s", f->name.len, f->name.txt);
2608 ###### ast functions
2609 static int find_struct_index(struct type *type, struct text field)
2612 for (i = 0; i < type->structure.nfields; i++)
2613 if (text_cmp(type->structure.fields[i].name, field) == 0)
2618 ###### propagate exec cases
2622 struct fieldref *f = cast(fieldref, prog);
2623 struct type *st = propagate_types(f->left, c, ok, NULL, 0);
2626 type_err(c, "error: unknown type for field access", f->left, // UNTESTED
2628 else if (st->init != structure_init)
2629 type_err(c, "error: field reference attempted on %1, not a struct",
2630 f->left, st, 0, NULL);
2631 else if (f->index == -2) {
2632 f->index = find_struct_index(st, f->name);
2634 type_err(c, "error: cannot find requested field in %1",
2635 f->left, st, 0, NULL);
2637 if (f->index >= 0) {
2638 struct type *ft = st->structure.fields[f->index].type;
2639 if (!type_compat(type, ft, rules))
2640 type_err(c, "error: have %1 but need %2", prog,
2647 ###### interp exec cases
2650 struct fieldref *f = cast(fieldref, e);
2652 struct value *lleft = linterp_exec(c, f->left, <ype);
2653 lrv = (void*)lleft->ptr + ltype->structure.fields[f->index].offset;
2654 rvtype = ltype->structure.fields[f->index].type;
2660 struct fieldlist *prev;
2664 ###### ast functions
2665 static void free_fieldlist(struct fieldlist *f)
2669 free_fieldlist(f->prev);
2671 free_value(f->f.type, f->f.init); // UNTESTED
2672 free(f->f.init); // UNTESTED
2677 ###### top level grammar
2678 DeclareStruct -> struct IDENTIFIER FieldBlock Newlines ${ {
2680 add_type(c, $2.txt, &structure_prototype);
2682 struct fieldlist *f;
2684 for (f = $3; f; f=f->prev)
2687 t->structure.nfields = cnt;
2688 t->structure.fields = calloc(cnt, sizeof(struct field));
2691 int a = f->f.type->align;
2693 t->structure.fields[cnt] = f->f;
2694 if (t->size & (a-1))
2695 t->size = (t->size | (a-1)) + 1;
2696 t->structure.fields[cnt].offset = t->size;
2697 t->size += ((f->f.type->size - 1) | (a-1)) + 1;
2706 FieldBlock -> { IN OptNL FieldLines OUT OptNL } ${ $0 = $<FL; }$
2707 | { SimpleFieldList } ${ $0 = $<SFL; }$
2708 | IN OptNL FieldLines OUT ${ $0 = $<FL; }$
2709 | SimpleFieldList EOL ${ $0 = $<SFL; }$
2711 FieldLines -> SimpleFieldList Newlines ${ $0 = $<SFL; }$
2712 | FieldLines SimpleFieldList Newlines ${
2717 SimpleFieldList -> Field ${ $0 = $<F; }$
2718 | SimpleFieldList ; Field ${
2722 | SimpleFieldList ; ${
2725 | ERROR ${ tok_err(c, "Syntax error in struct field", &$1); }$
2727 Field -> IDENTIFIER : Type = Expression ${ {
2730 $0 = calloc(1, sizeof(struct fieldlist));
2731 $0->f.name = $1.txt;
2736 propagate_types($<5, c, &ok, $3, 0);
2739 c->parse_error = 1; // UNTESTED
2741 struct value vl = interp_exec(c, $5, NULL);
2742 $0->f.init = global_alloc(c, $0->f.type, NULL, &vl);
2745 | IDENTIFIER : Type ${
2746 $0 = calloc(1, sizeof(struct fieldlist));
2747 $0->f.name = $1.txt;
2749 if ($0->f.type->prepare_type)
2750 $0->f.type->prepare_type(c, $0->f.type, 1);
2753 ###### forward decls
2754 static void structure_print_type(struct type *t, FILE *f);
2756 ###### value functions
2757 static void structure_print_type(struct type *t, FILE *f)
2761 fprintf(f, "struct %.*s\n", t->name.len, t->name.txt);
2763 for (i = 0; i < t->structure.nfields; i++) {
2764 struct field *fl = t->structure.fields + i;
2765 fprintf(f, " %.*s : ", fl->name.len, fl->name.txt);
2766 type_print(fl->type, f);
2767 if (fl->type->print && fl->init) {
2769 if (fl->type == Tstr)
2770 fprintf(f, "\""); // UNTESTED
2771 print_value(fl->type, fl->init, f);
2772 if (fl->type == Tstr)
2773 fprintf(f, "\""); // UNTESTED
2779 ###### print type decls
2784 while (target != 0) {
2786 for (t = context.typelist; t ; t=t->next)
2787 if (!t->anon && t->print_type_decl &&
2797 t->print_type_decl(t, stdout);
2805 A function is a chunk of code which can be passed parameters and can
2806 return results. Each function has a type which includes the set of
2807 parameters and the return value. As yet these types cannot be declared
2808 separately from the function itself.
2810 The parameters can be specified either in parentheses as a ';' separated
2813 ##### Example: function 1
2815 func main(av:[ac::number]string; env:[envc::number]string)
2818 or as an indented list of one parameter per line (though each line can
2819 be a ';' separated list)
2821 ##### Example: function 2
2824 argv:[argc::number]string
2825 env:[envc::number]string
2829 In the first case a return type can follow the parentheses after a colon,
2830 in the second it is given on a line starting with the word `return`.
2832 ##### Example: functions that return
2834 func add(a:number; b:number): number
2844 Rather than returning a type, the function can specify a set of local
2845 variables to return as a struct. The values of these variables when the
2846 function exits will be provided to the caller. For this the return type
2847 is replaced with a block of result declarations, either in parentheses
2848 or bracketed by `return` and `do`.
2850 ##### Example: functions returning multiple variables
2852 func to_cartesian(rho:number; theta:number):(x:number; y:number)
2865 For constructing the lists we use a `List` binode, which will be
2866 further detailed when Expression Lists are introduced.
2868 ###### type union fields
2871 struct binode *params;
2872 struct type *return_type;
2873 struct variable *scope;
2874 int inline_result; // return value is at start of 'local'
2878 ###### value union fields
2879 struct exec *function;
2881 ###### type functions
2882 void (*check_args)(struct parse_context *c, int *ok,
2883 struct type *require, struct exec *args);
2885 ###### value functions
2887 static void function_free(struct type *type, struct value *val)
2889 free_exec(val->function);
2890 val->function = NULL;
2893 static int function_compat(struct type *require, struct type *have)
2895 // FIXME can I do anything here yet?
2899 static void function_check_args(struct parse_context *c, int *ok,
2900 struct type *require, struct exec *args)
2902 /* This should be 'compat', but we don't have a 'tuple' type to
2903 * hold the type of 'args'
2905 struct binode *arg = cast(binode, args);
2906 struct binode *param = require->function.params;
2909 struct var *pv = cast(var, param->left);
2911 type_err(c, "error: insufficient arguments to function.",
2912 args, NULL, 0, NULL);
2916 propagate_types(arg->left, c, ok, pv->var->type, 0);
2917 param = cast(binode, param->right);
2918 arg = cast(binode, arg->right);
2921 type_err(c, "error: too many arguments to function.",
2922 args, NULL, 0, NULL);
2925 static void function_print(struct type *type, struct value *val, FILE *f)
2927 print_exec(val->function, 1, 0);
2930 static void function_print_type_decl(struct type *type, FILE *f)
2934 for (b = type->function.params; b; b = cast(binode, b->right)) {
2935 struct variable *v = cast(var, b->left)->var;
2936 fprintf(f, "%.*s%s", v->name->name.len, v->name->name.txt,
2937 v->constant ? "::" : ":");
2938 type_print(v->type, f);
2943 if (type->function.return_type != Tnone) {
2945 if (type->function.inline_result) {
2947 struct type *t = type->function.return_type;
2949 for (i = 0; i < t->structure.nfields; i++) {
2950 struct field *fl = t->structure.fields + i;
2953 fprintf(f, "%.*s:", fl->name.len, fl->name.txt);
2954 type_print(fl->type, f);
2958 type_print(type->function.return_type, f);
2963 static void function_free_type(struct type *t)
2965 free_exec(t->function.params);
2968 static struct type function_prototype = {
2969 .size = sizeof(void*),
2970 .align = sizeof(void*),
2971 .free = function_free,
2972 .compat = function_compat,
2973 .check_args = function_check_args,
2974 .print = function_print,
2975 .print_type_decl = function_print_type_decl,
2976 .free_type = function_free_type,
2979 ###### declare terminals
2989 FuncName -> IDENTIFIER ${ {
2990 struct variable *v = var_decl(c, $1.txt);
2991 struct var *e = new_pos(var, $1);
2997 v = var_ref(c, $1.txt);
2999 type_err(c, "error: function '%v' redeclared",
3001 type_err(c, "info: this is where '%v' was first declared",
3002 v->where_decl, NULL, 0, NULL);
3008 Args -> ArgsLine NEWLINE ${ $0 = $<AL; }$
3009 | Args ArgsLine NEWLINE ${ {
3010 struct binode *b = $<AL;
3011 struct binode **bp = &b;
3013 bp = (struct binode **)&(*bp)->left;
3018 ArgsLine -> ${ $0 = NULL; }$
3019 | Varlist ${ $0 = $<1; }$
3020 | Varlist ; ${ $0 = $<1; }$
3022 Varlist -> Varlist ; ArgDecl ${
3036 ArgDecl -> IDENTIFIER : FormalType ${ {
3037 struct variable *v = var_decl(c, $1.txt);
3043 ##### Function calls
3045 A function call can appear either as an expression or as a statement.
3046 We use a new 'Funcall' binode type to link the function with a list of
3047 arguments, form with the 'List' nodes.
3049 We have already seen the "Term" which is how a function call can appear
3050 in an expression. To parse a function call into a statement we include
3051 it in the "SimpleStatement Grammar" which will be described later.
3057 | Term ( ExpressionList ) ${ {
3058 struct binode *b = new(binode);
3061 b->right = reorder_bilist($<EL);
3065 struct binode *b = new(binode);
3072 ###### SimpleStatement Grammar
3074 | Term ( ExpressionList ) ${ {
3075 struct binode *b = new(binode);
3078 b->right = reorder_bilist($<EL);
3082 ###### print binode cases
3085 do_indent(indent, "");
3086 print_exec(b->left, -1, bracket);
3088 for (b = cast(binode, b->right); b; b = cast(binode, b->right)) {
3091 print_exec(b->left, -1, bracket);
3101 ###### propagate binode cases
3104 /* Every arg must match formal parameter, and result
3105 * is return type of function
3107 struct binode *args = cast(binode, b->right);
3108 struct var *v = cast(var, b->left);
3110 if (!v->var->type || v->var->type->check_args == NULL) {
3111 type_err(c, "error: attempt to call a non-function.",
3112 prog, NULL, 0, NULL);
3115 v->var->type->check_args(c, ok, v->var->type, args);
3116 return v->var->type->function.return_type;
3119 ###### interp binode cases
3122 struct var *v = cast(var, b->left);
3123 struct type *t = v->var->type;
3124 void *oldlocal = c->local;
3125 int old_size = c->local_size;
3126 void *local = calloc(1, t->function.local_size);
3127 struct value *fbody = var_value(c, v->var);
3128 struct binode *arg = cast(binode, b->right);
3129 struct binode *param = t->function.params;
3132 struct var *pv = cast(var, param->left);
3133 struct type *vtype = NULL;
3134 struct value val = interp_exec(c, arg->left, &vtype);
3136 c->local = local; c->local_size = t->function.local_size;
3137 lval = var_value(c, pv->var);
3138 c->local = oldlocal; c->local_size = old_size;
3139 memcpy(lval, &val, vtype->size);
3140 param = cast(binode, param->right);
3141 arg = cast(binode, arg->right);
3143 c->local = local; c->local_size = t->function.local_size;
3144 if (t->function.inline_result && dtype) {
3145 _interp_exec(c, fbody->function, NULL, NULL);
3146 memcpy(dest, local, dtype->size);
3147 rvtype = ret.type = NULL;
3149 rv = interp_exec(c, fbody->function, &rvtype);
3150 c->local = oldlocal; c->local_size = old_size;
3155 ## Complex executables: statements and expressions
3157 Now that we have types and values and variables and most of the basic
3158 Terms which provide access to these, we can explore the more complex
3159 code that combine all of these to get useful work done. Specifically
3160 statements and expressions.
3162 Expressions are various combinations of Terms. We will use operator
3163 precedence to ensure correct parsing. The simplest Expression is just a
3164 Term - others will follow.
3169 Expression -> Term ${ $0 = $<Term; }$
3170 ## expression grammar
3172 ### Expressions: Conditional
3174 Our first user of the `binode` will be conditional expressions, which
3175 is a bit odd as they actually have three components. That will be
3176 handled by having 2 binodes for each expression. The conditional
3177 expression is the lowest precedence operator which is why we define it
3178 first - to start the precedence list.
3180 Conditional expressions are of the form "value `if` condition `else`
3181 other_value". They associate to the right, so everything to the right
3182 of `else` is part of an else value, while only a higher-precedence to
3183 the left of `if` is the if values. Between `if` and `else` there is no
3184 room for ambiguity, so a full conditional expression is allowed in
3190 ###### declare terminals
3194 ###### expression grammar
3196 | Expression if Expression else Expression $$ifelse ${ {
3197 struct binode *b1 = new(binode);
3198 struct binode *b2 = new(binode);
3208 ###### print binode cases
3211 b2 = cast(binode, b->right);
3212 if (bracket) printf("(");
3213 print_exec(b2->left, -1, bracket);
3215 print_exec(b->left, -1, bracket);
3217 print_exec(b2->right, -1, bracket);
3218 if (bracket) printf(")");
3221 ###### propagate binode cases
3224 /* cond must be Tbool, others must match */
3225 struct binode *b2 = cast(binode, b->right);
3228 propagate_types(b->left, c, ok, Tbool, 0);
3229 t = propagate_types(b2->left, c, ok, type, Rnolabel);
3230 t2 = propagate_types(b2->right, c, ok, type ?: t, Rnolabel);
3234 ###### interp binode cases
3237 struct binode *b2 = cast(binode, b->right);
3238 left = interp_exec(c, b->left, <ype);
3240 rv = interp_exec(c, b2->left, &rvtype); // UNTESTED
3242 rv = interp_exec(c, b2->right, &rvtype);
3248 We take a brief detour, now that we have expressions, to describe lists
3249 of expressions. These will be needed for function parameters and
3250 possibly other situations. They seem generic enough to introduce here
3251 to be used elsewhere.
3253 And ExpressionList will use the `List` type of `binode`, building up at
3254 the end. And place where they are used will probably call
3255 `reorder_bilist()` to get a more normal first/next arrangement.
3257 ###### declare terminals
3260 `List` execs have no implicit semantics, so they are never propagated or
3261 interpreted. The can be printed as a comma separate list, which is how
3262 they are parsed. Note they are also used for function formal parameter
3263 lists. In that case a separate function is used to print them.
3265 ###### print binode cases
3269 print_exec(b->left, -1, bracket);
3272 b = cast(binode, b->right);
3276 ###### propagate binode cases
3277 case List: abort(); // NOTEST
3278 ###### interp binode cases
3279 case List: abort(); // NOTEST
3284 ExpressionList -> ExpressionList , Expression ${
3297 ### Expressions: Boolean
3299 The next class of expressions to use the `binode` will be Boolean
3300 expressions. "`and then`" and "`or else`" are similar to `and` and `or`
3301 have same corresponding precendence. The difference is that they don't
3302 evaluate the second expression if not necessary.
3311 ###### declare terminals
3316 ###### expression grammar
3317 | Expression or Expression ${ {
3318 struct binode *b = new(binode);
3324 | Expression or else Expression ${ {
3325 struct binode *b = new(binode);
3332 | Expression and Expression ${ {
3333 struct binode *b = new(binode);
3339 | Expression and then Expression ${ {
3340 struct binode *b = new(binode);
3347 | not Expression ${ {
3348 struct binode *b = new(binode);
3354 ###### print binode cases
3356 if (bracket) printf("(");
3357 print_exec(b->left, -1, bracket);
3359 print_exec(b->right, -1, bracket);
3360 if (bracket) printf(")");
3363 if (bracket) printf("(");
3364 print_exec(b->left, -1, bracket);
3365 printf(" and then ");
3366 print_exec(b->right, -1, bracket);
3367 if (bracket) printf(")");
3370 if (bracket) printf("(");
3371 print_exec(b->left, -1, bracket);
3373 print_exec(b->right, -1, bracket);
3374 if (bracket) printf(")");
3377 if (bracket) printf("(");
3378 print_exec(b->left, -1, bracket);
3379 printf(" or else ");
3380 print_exec(b->right, -1, bracket);
3381 if (bracket) printf(")");
3384 if (bracket) printf("(");
3386 print_exec(b->right, -1, bracket);
3387 if (bracket) printf(")");
3390 ###### propagate binode cases
3396 /* both must be Tbool, result is Tbool */
3397 propagate_types(b->left, c, ok, Tbool, 0);
3398 propagate_types(b->right, c, ok, Tbool, 0);
3399 if (type && type != Tbool)
3400 type_err(c, "error: %1 operation found where %2 expected", prog,
3404 ###### interp binode cases
3406 rv = interp_exec(c, b->left, &rvtype);
3407 right = interp_exec(c, b->right, &rtype);
3408 rv.bool = rv.bool && right.bool;
3411 rv = interp_exec(c, b->left, &rvtype);
3413 rv = interp_exec(c, b->right, NULL);
3416 rv = interp_exec(c, b->left, &rvtype);
3417 right = interp_exec(c, b->right, &rtype);
3418 rv.bool = rv.bool || right.bool;
3421 rv = interp_exec(c, b->left, &rvtype);
3423 rv = interp_exec(c, b->right, NULL);
3426 rv = interp_exec(c, b->right, &rvtype);
3430 ### Expressions: Comparison
3432 Of slightly higher precedence that Boolean expressions are Comparisons.
3433 A comparison takes arguments of any comparable type, but the two types
3436 To simplify the parsing we introduce an `eop` which can record an
3437 expression operator, and the `CMPop` non-terminal will match one of them.
3444 ###### ast functions
3445 static void free_eop(struct eop *e)
3459 ###### declare terminals
3460 $LEFT < > <= >= == != CMPop
3462 ###### expression grammar
3463 | Expression CMPop Expression ${ {
3464 struct binode *b = new(binode);
3474 CMPop -> < ${ $0.op = Less; }$
3475 | > ${ $0.op = Gtr; }$
3476 | <= ${ $0.op = LessEq; }$
3477 | >= ${ $0.op = GtrEq; }$
3478 | == ${ $0.op = Eql; }$
3479 | != ${ $0.op = NEql; }$
3481 ###### print binode cases
3489 if (bracket) printf("(");
3490 print_exec(b->left, -1, bracket);
3492 case Less: printf(" < "); break;
3493 case LessEq: printf(" <= "); break;
3494 case Gtr: printf(" > "); break;
3495 case GtrEq: printf(" >= "); break;
3496 case Eql: printf(" == "); break;
3497 case NEql: printf(" != "); break;
3498 default: abort(); // NOTEST
3500 print_exec(b->right, -1, bracket);
3501 if (bracket) printf(")");
3504 ###### propagate binode cases
3511 /* Both must match but not be labels, result is Tbool */
3512 t = propagate_types(b->left, c, ok, NULL, Rnolabel);
3514 propagate_types(b->right, c, ok, t, 0);
3516 t = propagate_types(b->right, c, ok, NULL, Rnolabel); // UNTESTED
3518 t = propagate_types(b->left, c, ok, t, 0); // UNTESTED
3520 if (!type_compat(type, Tbool, 0))
3521 type_err(c, "error: Comparison returns %1 but %2 expected", prog,
3522 Tbool, rules, type);
3525 ###### interp binode cases
3534 left = interp_exec(c, b->left, <ype);
3535 right = interp_exec(c, b->right, &rtype);
3536 cmp = value_cmp(ltype, rtype, &left, &right);
3539 case Less: rv.bool = cmp < 0; break;
3540 case LessEq: rv.bool = cmp <= 0; break;
3541 case Gtr: rv.bool = cmp > 0; break;
3542 case GtrEq: rv.bool = cmp >= 0; break;
3543 case Eql: rv.bool = cmp == 0; break;
3544 case NEql: rv.bool = cmp != 0; break;
3545 default: rv.bool = 0; break; // NOTEST
3550 ### Expressions: Arithmetic etc.
3552 The remaining expressions with the highest precedence are arithmetic,
3553 string concatenation, and string conversion. String concatenation
3554 (`++`) has the same precedence as multiplication and division, but lower
3557 String conversion is a temporary feature until I get a better type
3558 system. `$` is a prefix operator which expects a string and returns
3561 `+` and `-` are both infix and prefix operations (where they are
3562 absolute value and negation). These have different operator names.
3564 We also have a 'Bracket' operator which records where parentheses were
3565 found. This makes it easy to reproduce these when printing. Possibly I
3566 should only insert brackets were needed for precedence. Putting
3567 parentheses around an expression converts it into a Term,
3577 ###### declare terminals
3583 ###### expression grammar
3584 | Expression Eop Expression ${ {
3585 struct binode *b = new(binode);
3592 | Expression Top Expression ${ {
3593 struct binode *b = new(binode);
3600 | Uop Expression ${ {
3601 struct binode *b = new(binode);
3609 | ( Expression ) ${ {
3610 struct binode *b = new_pos(binode, $1);
3619 Eop -> + ${ $0.op = Plus; }$
3620 | - ${ $0.op = Minus; }$
3622 Uop -> + ${ $0.op = Absolute; }$
3623 | - ${ $0.op = Negate; }$
3624 | $ ${ $0.op = StringConv; }$
3626 Top -> * ${ $0.op = Times; }$
3627 | / ${ $0.op = Divide; }$
3628 | % ${ $0.op = Rem; }$
3629 | ++ ${ $0.op = Concat; }$
3631 ###### print binode cases
3638 if (bracket) printf("(");
3639 print_exec(b->left, indent, bracket);
3641 case Plus: fputs(" + ", stdout); break;
3642 case Minus: fputs(" - ", stdout); break;
3643 case Times: fputs(" * ", stdout); break;
3644 case Divide: fputs(" / ", stdout); break;
3645 case Rem: fputs(" % ", stdout); break;
3646 case Concat: fputs(" ++ ", stdout); break;
3647 default: abort(); // NOTEST
3649 print_exec(b->right, indent, bracket);
3650 if (bracket) printf(")");
3655 if (bracket) printf("(");
3657 case Absolute: fputs("+", stdout); break;
3658 case Negate: fputs("-", stdout); break;
3659 case StringConv: fputs("$", stdout); break;
3660 default: abort(); // NOTEST
3662 print_exec(b->right, indent, bracket);
3663 if (bracket) printf(")");
3667 print_exec(b->right, indent, bracket);
3671 ###### propagate binode cases
3677 /* both must be numbers, result is Tnum */
3680 /* as propagate_types ignores a NULL,
3681 * unary ops fit here too */
3682 propagate_types(b->left, c, ok, Tnum, 0);
3683 propagate_types(b->right, c, ok, Tnum, 0);
3684 if (!type_compat(type, Tnum, 0))
3685 type_err(c, "error: Arithmetic returns %1 but %2 expected", prog,
3690 /* both must be Tstr, result is Tstr */
3691 propagate_types(b->left, c, ok, Tstr, 0);
3692 propagate_types(b->right, c, ok, Tstr, 0);
3693 if (!type_compat(type, Tstr, 0))
3694 type_err(c, "error: Concat returns %1 but %2 expected", prog,
3699 /* op must be string, result is number */
3700 propagate_types(b->left, c, ok, Tstr, 0);
3701 if (!type_compat(type, Tnum, 0))
3702 type_err(c, // UNTESTED
3703 "error: Can only convert string to number, not %1",
3704 prog, type, 0, NULL);
3708 return propagate_types(b->right, c, ok, type, 0);
3710 ###### interp binode cases
3713 rv = interp_exec(c, b->left, &rvtype);
3714 right = interp_exec(c, b->right, &rtype);
3715 mpq_add(rv.num, rv.num, right.num);
3718 rv = interp_exec(c, b->left, &rvtype);
3719 right = interp_exec(c, b->right, &rtype);
3720 mpq_sub(rv.num, rv.num, right.num);
3723 rv = interp_exec(c, b->left, &rvtype);
3724 right = interp_exec(c, b->right, &rtype);
3725 mpq_mul(rv.num, rv.num, right.num);
3728 rv = interp_exec(c, b->left, &rvtype);
3729 right = interp_exec(c, b->right, &rtype);
3730 mpq_div(rv.num, rv.num, right.num);
3735 left = interp_exec(c, b->left, <ype);
3736 right = interp_exec(c, b->right, &rtype);
3737 mpz_init(l); mpz_init(r); mpz_init(rem);
3738 mpz_tdiv_q(l, mpq_numref(left.num), mpq_denref(left.num));
3739 mpz_tdiv_q(r, mpq_numref(right.num), mpq_denref(right.num));
3740 mpz_tdiv_r(rem, l, r);
3741 val_init(Tnum, &rv);
3742 mpq_set_z(rv.num, rem);
3743 mpz_clear(r); mpz_clear(l); mpz_clear(rem);
3748 rv = interp_exec(c, b->right, &rvtype);
3749 mpq_neg(rv.num, rv.num);
3752 rv = interp_exec(c, b->right, &rvtype);
3753 mpq_abs(rv.num, rv.num);
3756 rv = interp_exec(c, b->right, &rvtype);
3759 left = interp_exec(c, b->left, <ype);
3760 right = interp_exec(c, b->right, &rtype);
3762 rv.str = text_join(left.str, right.str);
3765 right = interp_exec(c, b->right, &rvtype);
3769 struct text tx = right.str;
3772 if (tx.txt[0] == '-') {
3773 neg = 1; // UNTESTED
3774 tx.txt++; // UNTESTED
3775 tx.len--; // UNTESTED
3777 if (number_parse(rv.num, tail, tx) == 0)
3778 mpq_init(rv.num); // UNTESTED
3780 mpq_neg(rv.num, rv.num); // UNTESTED
3782 printf("Unsupported suffix: %.*s\n", tx.len, tx.txt); // UNTESTED
3786 ###### value functions
3788 static struct text text_join(struct text a, struct text b)
3791 rv.len = a.len + b.len;
3792 rv.txt = malloc(rv.len);
3793 memcpy(rv.txt, a.txt, a.len);
3794 memcpy(rv.txt+a.len, b.txt, b.len);
3798 ### Blocks, Statements, and Statement lists.
3800 Now that we have expressions out of the way we need to turn to
3801 statements. There are simple statements and more complex statements.
3802 Simple statements do not contain (syntactic) newlines, complex statements do.
3804 Statements often come in sequences and we have corresponding simple
3805 statement lists and complex statement lists.
3806 The former comprise only simple statements separated by semicolons.
3807 The later comprise complex statements and simple statement lists. They are
3808 separated by newlines. Thus the semicolon is only used to separate
3809 simple statements on the one line. This may be overly restrictive,
3810 but I'm not sure I ever want a complex statement to share a line with
3813 Note that a simple statement list can still use multiple lines if
3814 subsequent lines are indented, so
3816 ###### Example: wrapped simple statement list
3821 is a single simple statement list. This might allow room for
3822 confusion, so I'm not set on it yet.
3824 A simple statement list needs no extra syntax. A complex statement
3825 list has two syntactic forms. It can be enclosed in braces (much like
3826 C blocks), or it can be introduced by an indent and continue until an
3827 unindented newline (much like Python blocks). With this extra syntax
3828 it is referred to as a block.
3830 Note that a block does not have to include any newlines if it only
3831 contains simple statements. So both of:
3833 if condition: a=b; d=f
3835 if condition { a=b; print f }
3839 In either case the list is constructed from a `binode` list with
3840 `Block` as the operator. When parsing the list it is most convenient
3841 to append to the end, so a list is a list and a statement. When using
3842 the list it is more convenient to consider a list to be a statement
3843 and a list. So we need a function to re-order a list.
3844 `reorder_bilist` serves this purpose.
3846 The only stand-alone statement we introduce at this stage is `pass`
3847 which does nothing and is represented as a `NULL` pointer in a `Block`
3848 list. Other stand-alone statements will follow once the infrastructure
3851 As many statements will use binodes, we declare a binode pointer 'b' in
3852 the common header for all reductions to use.
3854 ###### Parser: reduce
3865 Block -> { IN OptNL Statementlist OUT OptNL } ${ $0 = $<Sl; }$
3866 | { SimpleStatements } ${ $0 = reorder_bilist($<SS); }$
3867 | SimpleStatements ; ${ $0 = reorder_bilist($<SS); }$
3868 | SimpleStatements EOL ${ $0 = reorder_bilist($<SS); }$
3869 | IN OptNL Statementlist OUT ${ $0 = $<Sl; }$
3871 OpenBlock -> OpenScope { IN OptNL Statementlist OUT OptNL } ${ $0 = $<Sl; }$
3872 | OpenScope { SimpleStatements } ${ $0 = reorder_bilist($<SS); }$
3873 | OpenScope SimpleStatements ; ${ $0 = reorder_bilist($<SS); }$
3874 | OpenScope SimpleStatements EOL ${ $0 = reorder_bilist($<SS); }$
3875 | IN OpenScope OptNL Statementlist OUT ${ $0 = $<Sl; }$
3877 UseBlock -> { OpenScope IN OptNL Statementlist OUT OptNL } ${ $0 = $<Sl; }$
3878 | { OpenScope SimpleStatements } ${ $0 = reorder_bilist($<SS); }$
3879 | IN OpenScope OptNL Statementlist OUT ${ $0 = $<Sl; }$
3881 ColonBlock -> { IN OptNL Statementlist OUT OptNL } ${ $0 = $<Sl; }$
3882 | { SimpleStatements } ${ $0 = reorder_bilist($<SS); }$
3883 | : SimpleStatements ; ${ $0 = reorder_bilist($<SS); }$
3884 | : SimpleStatements EOL ${ $0 = reorder_bilist($<SS); }$
3885 | : IN OptNL Statementlist OUT ${ $0 = $<Sl; }$
3887 Statementlist -> ComplexStatements ${ $0 = reorder_bilist($<CS); }$
3889 ComplexStatements -> ComplexStatements ComplexStatement ${
3899 | ComplexStatement ${
3911 ComplexStatement -> SimpleStatements Newlines ${
3912 $0 = reorder_bilist($<SS);
3914 | SimpleStatements ; Newlines ${
3915 $0 = reorder_bilist($<SS);
3917 ## ComplexStatement Grammar
3920 SimpleStatements -> SimpleStatements ; SimpleStatement ${
3926 | SimpleStatement ${
3935 SimpleStatement -> pass ${ $0 = NULL; }$
3936 | ERROR ${ tok_err(c, "Syntax error in statement", &$1); }$
3937 ## SimpleStatement Grammar
3939 ###### print binode cases
3943 if (b->left == NULL) // UNTESTED
3944 printf("pass"); // UNTESTED
3946 print_exec(b->left, indent, bracket); // UNTESTED
3947 if (b->right) { // UNTESTED
3948 printf("; "); // UNTESTED
3949 print_exec(b->right, indent, bracket); // UNTESTED
3952 // block, one per line
3953 if (b->left == NULL)
3954 do_indent(indent, "pass\n");
3956 print_exec(b->left, indent, bracket);
3958 print_exec(b->right, indent, bracket);
3962 ###### propagate binode cases
3965 /* If any statement returns something other than Tnone
3966 * or Tbool then all such must return same type.
3967 * As each statement may be Tnone or something else,
3968 * we must always pass NULL (unknown) down, otherwise an incorrect
3969 * error might occur. We never return Tnone unless it is
3974 for (e = b; e; e = cast(binode, e->right)) {
3975 t = propagate_types(e->left, c, ok, NULL, rules);
3976 if ((rules & Rboolok) && (t == Tbool || t == Tnone))
3978 if (t == Tnone && e->right)
3979 /* Only the final statement *must* return a value
3987 type_err(c, "error: expected %1%r, found %2",
3988 e->left, type, rules, t);
3994 ###### interp binode cases
3996 while (rvtype == Tnone &&
3999 rv = interp_exec(c, b->left, &rvtype);
4000 b = cast(binode, b->right);
4004 ### The Print statement
4006 `print` is a simple statement that takes a comma-separated list of
4007 expressions and prints the values separated by spaces and terminated
4008 by a newline. No control of formatting is possible.
4010 `print` uses `ExpressionList` to collect the expressions and stores them
4011 on the left side of a `Print` binode unlessthere is a trailing comma
4012 when the list is stored on the `right` side and no trailing newline is
4018 ##### declare terminals
4021 ###### SimpleStatement Grammar
4023 | print ExpressionList ${
4024 $0 = b = new(binode);
4027 b->left = reorder_bilist($<EL);
4029 | print ExpressionList , ${ {
4030 $0 = b = new(binode);
4032 b->right = reorder_bilist($<EL);
4036 $0 = b = new(binode);
4042 ###### print binode cases
4045 do_indent(indent, "print");
4047 print_exec(b->right, -1, bracket);
4050 print_exec(b->left, -1, bracket);
4055 ###### propagate binode cases
4058 /* don't care but all must be consistent */
4060 b = cast(binode, b->left);
4062 b = cast(binode, b->right);
4064 propagate_types(b->left, c, ok, NULL, Rnolabel);
4065 b = cast(binode, b->right);
4069 ###### interp binode cases
4073 struct binode *b2 = cast(binode, b->left);
4075 b2 = cast(binode, b->right);
4076 for (; b2; b2 = cast(binode, b2->right)) {
4077 left = interp_exec(c, b2->left, <ype);
4078 print_value(ltype, &left, stdout);
4079 free_value(ltype, &left);
4083 if (b->right == NULL)
4089 ###### Assignment statement
4091 An assignment will assign a value to a variable, providing it hasn't
4092 been declared as a constant. The analysis phase ensures that the type
4093 will be correct so the interpreter just needs to perform the
4094 calculation. There is a form of assignment which declares a new
4095 variable as well as assigning a value. If a name is assigned before
4096 it is declared, and error will be raised as the name is created as
4097 `Tlabel` and it is illegal to assign to such names.
4103 ###### declare terminals
4106 ###### SimpleStatement Grammar
4107 | Term = Expression ${
4108 $0 = b= new(binode);
4113 | VariableDecl = Expression ${
4114 $0 = b= new(binode);
4121 if ($1->var->where_set == NULL) {
4123 "Variable declared with no type or value: %v",
4127 $0 = b = new(binode);
4134 ###### print binode cases
4137 do_indent(indent, "");
4138 print_exec(b->left, indent, bracket);
4140 print_exec(b->right, indent, bracket);
4147 struct variable *v = cast(var, b->left)->var;
4148 do_indent(indent, "");
4149 print_exec(b->left, indent, bracket);
4150 if (cast(var, b->left)->var->constant) {
4152 if (v->explicit_type) {
4153 type_print(v->type, stdout);
4158 if (v->explicit_type) {
4159 type_print(v->type, stdout);
4165 print_exec(b->right, indent, bracket);
4172 ###### propagate binode cases
4176 /* Both must match and not be labels,
4177 * Type must support 'dup',
4178 * For Assign, left must not be constant.
4181 t = propagate_types(b->left, c, ok, NULL,
4182 Rnolabel | (b->op == Assign ? Rnoconstant : 0));
4187 if (propagate_types(b->right, c, ok, t, 0) != t)
4188 if (b->left->type == Xvar)
4189 type_err(c, "info: variable '%v' was set as %1 here.",
4190 cast(var, b->left)->var->where_set, t, rules, NULL);
4192 t = propagate_types(b->right, c, ok, NULL, Rnolabel);
4194 propagate_types(b->left, c, ok, t,
4195 (b->op == Assign ? Rnoconstant : 0));
4197 if (t && t->dup == NULL && t->name.txt[0] != ' ') // HACK
4198 type_err(c, "error: cannot assign value of type %1", b, t, 0, NULL);
4203 ###### interp binode cases
4206 lleft = linterp_exec(c, b->left, <ype);
4208 dinterp_exec(c, b->right, lleft, ltype, 1);
4214 struct variable *v = cast(var, b->left)->var;
4217 val = var_value(c, v);
4218 if (v->type->prepare_type)
4219 v->type->prepare_type(c, v->type, 0);
4221 dinterp_exec(c, b->right, val, v->type, 0);
4223 val_init(v->type, val);
4227 ### The `use` statement
4229 The `use` statement is the last "simple" statement. It is needed when a
4230 statement block can return a value. This includes the body of a
4231 function which has a return type, and the "condition" code blocks in
4232 `if`, `while`, and `switch` statements.
4237 ###### declare terminals
4240 ###### SimpleStatement Grammar
4242 $0 = b = new_pos(binode, $1);
4245 if (b->right->type == Xvar) {
4246 struct var *v = cast(var, b->right);
4247 if (v->var->type == Tnone) {
4248 /* Convert this to a label */
4251 v->var->type = Tlabel;
4252 val = global_alloc(c, Tlabel, v->var, NULL);
4258 ###### print binode cases
4261 do_indent(indent, "use ");
4262 print_exec(b->right, -1, bracket);
4267 ###### propagate binode cases
4270 /* result matches value */
4271 return propagate_types(b->right, c, ok, type, 0);
4273 ###### interp binode cases
4276 rv = interp_exec(c, b->right, &rvtype);
4279 ### The Conditional Statement
4281 This is the biggy and currently the only complex statement. This
4282 subsumes `if`, `while`, `do/while`, `switch`, and some parts of `for`.
4283 It is comprised of a number of parts, all of which are optional though
4284 set combinations apply. Each part is (usually) a key word (`then` is
4285 sometimes optional) followed by either an expression or a code block,
4286 except the `casepart` which is a "key word and an expression" followed
4287 by a code block. The code-block option is valid for all parts and,
4288 where an expression is also allowed, the code block can use the `use`
4289 statement to report a value. If the code block does not report a value
4290 the effect is similar to reporting `True`.
4292 The `else` and `case` parts, as well as `then` when combined with
4293 `if`, can contain a `use` statement which will apply to some
4294 containing conditional statement. `for` parts, `do` parts and `then`
4295 parts used with `for` can never contain a `use`, except in some
4296 subordinate conditional statement.
4298 If there is a `forpart`, it is executed first, only once.
4299 If there is a `dopart`, then it is executed repeatedly providing
4300 always that the `condpart` or `cond`, if present, does not return a non-True
4301 value. `condpart` can fail to return any value if it simply executes
4302 to completion. This is treated the same as returning `True`.
4304 If there is a `thenpart` it will be executed whenever the `condpart`
4305 or `cond` returns True (or does not return any value), but this will happen
4306 *after* `dopart` (when present).
4308 If `elsepart` is present it will be executed at most once when the
4309 condition returns `False` or some value that isn't `True` and isn't
4310 matched by any `casepart`. If there are any `casepart`s, they will be
4311 executed when the condition returns a matching value.
4313 The particular sorts of values allowed in case parts has not yet been
4314 determined in the language design, so nothing is prohibited.
4316 The various blocks in this complex statement potentially provide scope
4317 for variables as described earlier. Each such block must include the
4318 "OpenScope" nonterminal before parsing the block, and must call
4319 `var_block_close()` when closing the block.
4321 The code following "`if`", "`switch`" and "`for`" does not get its own
4322 scope, but is in a scope covering the whole statement, so names
4323 declared there cannot be redeclared elsewhere. Similarly the
4324 condition following "`while`" is in a scope the covers the body
4325 ("`do`" part) of the loop, and which does not allow conditional scope
4326 extension. Code following "`then`" (both looping and non-looping),
4327 "`else`" and "`case`" each get their own local scope.
4329 The type requirements on the code block in a `whilepart` are quite
4330 unusal. It is allowed to return a value of some identifiable type, in
4331 which case the loop aborts and an appropriate `casepart` is run, or it
4332 can return a Boolean, in which case the loop either continues to the
4333 `dopart` (on `True`) or aborts and runs the `elsepart` (on `False`).
4334 This is different both from the `ifpart` code block which is expected to
4335 return a Boolean, or the `switchpart` code block which is expected to
4336 return the same type as the casepart values. The correct analysis of
4337 the type of the `whilepart` code block is the reason for the
4338 `Rboolok` flag which is passed to `propagate_types()`.
4340 The `cond_statement` cannot fit into a `binode` so a new `exec` is
4341 defined. As there are two scopes which cover multiple parts - one for
4342 the whole statement and one for "while" and "do" - and as we will use
4343 the 'struct exec' to track scopes, we actually need two new types of
4344 exec. One is a `binode` for the looping part, the rest is the
4345 `cond_statement`. The `cond_statement` will use an auxilliary `struct
4346 casepart` to track a list of case parts.
4357 struct exec *action;
4358 struct casepart *next;
4360 struct cond_statement {
4362 struct exec *forpart, *condpart, *thenpart, *elsepart;
4363 struct binode *looppart;
4364 struct casepart *casepart;
4367 ###### ast functions
4369 static void free_casepart(struct casepart *cp)
4373 free_exec(cp->value);
4374 free_exec(cp->action);
4381 static void free_cond_statement(struct cond_statement *s)
4385 free_exec(s->forpart);
4386 free_exec(s->condpart);
4387 free_exec(s->looppart);
4388 free_exec(s->thenpart);
4389 free_exec(s->elsepart);
4390 free_casepart(s->casepart);
4394 ###### free exec cases
4395 case Xcond_statement: free_cond_statement(cast(cond_statement, e)); break;
4397 ###### ComplexStatement Grammar
4398 | CondStatement ${ $0 = $<1; }$
4400 ###### declare terminals
4401 $TERM for then while do
4408 // A CondStatement must end with EOL, as does CondSuffix and
4410 // ForPart, ThenPart, SwitchPart, CasePart are non-empty and
4411 // may or may not end with EOL
4412 // WhilePart and IfPart include an appropriate Suffix
4414 // ForPart, SwitchPart, and IfPart open scopes, o we have to close
4415 // them. WhilePart opens and closes its own scope.
4416 CondStatement -> ForPart OptNL ThenPart OptNL WhilePart CondSuffix ${
4419 $0->thenpart = $<TP;
4420 $0->looppart = $<WP;
4421 var_block_close(c, CloseSequential, $0);
4423 | ForPart OptNL WhilePart CondSuffix ${
4426 $0->looppart = $<WP;
4427 var_block_close(c, CloseSequential, $0);
4429 | WhilePart CondSuffix ${
4431 $0->looppart = $<WP;
4433 | SwitchPart OptNL CasePart CondSuffix ${
4435 $0->condpart = $<SP;
4436 $CP->next = $0->casepart;
4437 $0->casepart = $<CP;
4438 var_block_close(c, CloseSequential, $0);
4440 | SwitchPart : IN OptNL CasePart CondSuffix OUT Newlines ${
4442 $0->condpart = $<SP;
4443 $CP->next = $0->casepart;
4444 $0->casepart = $<CP;
4445 var_block_close(c, CloseSequential, $0);
4447 | IfPart IfSuffix ${
4449 $0->condpart = $IP.condpart; $IP.condpart = NULL;
4450 $0->thenpart = $IP.thenpart; $IP.thenpart = NULL;
4451 // This is where we close an "if" statement
4452 var_block_close(c, CloseSequential, $0);
4455 CondSuffix -> IfSuffix ${
4458 | Newlines CasePart CondSuffix ${
4460 $CP->next = $0->casepart;
4461 $0->casepart = $<CP;
4463 | CasePart CondSuffix ${
4465 $CP->next = $0->casepart;
4466 $0->casepart = $<CP;
4469 IfSuffix -> Newlines ${ $0 = new(cond_statement); }$
4470 | Newlines ElsePart ${ $0 = $<EP; }$
4471 | ElsePart ${$0 = $<EP; }$
4473 ElsePart -> else OpenBlock Newlines ${
4474 $0 = new(cond_statement);
4475 $0->elsepart = $<OB;
4476 var_block_close(c, CloseElse, $0->elsepart);
4478 | else OpenScope CondStatement ${
4479 $0 = new(cond_statement);
4480 $0->elsepart = $<CS;
4481 var_block_close(c, CloseElse, $0->elsepart);
4485 CasePart -> case Expression OpenScope ColonBlock ${
4486 $0 = calloc(1,sizeof(struct casepart));
4489 var_block_close(c, CloseParallel, $0->action);
4493 // These scopes are closed in CondStatement
4494 ForPart -> for OpenBlock ${
4498 ThenPart -> then OpenBlock ${
4500 var_block_close(c, CloseSequential, $0);
4504 // This scope is closed in CondStatement
4505 WhilePart -> while UseBlock OptNL do OpenBlock ${
4510 var_block_close(c, CloseSequential, $0->right);
4511 var_block_close(c, CloseSequential, $0);
4513 | while OpenScope Expression OpenScope ColonBlock ${
4518 var_block_close(c, CloseSequential, $0->right);
4519 var_block_close(c, CloseSequential, $0);
4523 IfPart -> if UseBlock OptNL then OpenBlock ${
4526 var_block_close(c, CloseParallel, $0.thenpart);
4528 | if OpenScope Expression OpenScope ColonBlock ${
4531 var_block_close(c, CloseParallel, $0.thenpart);
4533 | if OpenScope Expression OpenScope OptNL then Block ${
4536 var_block_close(c, CloseParallel, $0.thenpart);
4540 // This scope is closed in CondStatement
4541 SwitchPart -> switch OpenScope Expression ${
4544 | switch UseBlock ${
4548 ###### print binode cases
4550 if (b->left && b->left->type == Xbinode &&
4551 cast(binode, b->left)->op == Block) {
4553 do_indent(indent, "while {\n");
4555 do_indent(indent, "while\n");
4556 print_exec(b->left, indent+1, bracket);
4558 do_indent(indent, "} do {\n");
4560 do_indent(indent, "do\n");
4561 print_exec(b->right, indent+1, bracket);
4563 do_indent(indent, "}\n");
4565 do_indent(indent, "while ");
4566 print_exec(b->left, 0, bracket);
4571 print_exec(b->right, indent+1, bracket);
4573 do_indent(indent, "}\n");
4577 ###### print exec cases
4579 case Xcond_statement:
4581 struct cond_statement *cs = cast(cond_statement, e);
4582 struct casepart *cp;
4584 do_indent(indent, "for");
4585 if (bracket) printf(" {\n"); else printf("\n");
4586 print_exec(cs->forpart, indent+1, bracket);
4589 do_indent(indent, "} then {\n");
4591 do_indent(indent, "then\n");
4592 print_exec(cs->thenpart, indent+1, bracket);
4594 if (bracket) do_indent(indent, "}\n");
4597 print_exec(cs->looppart, indent, bracket);
4601 do_indent(indent, "switch");
4603 do_indent(indent, "if");
4604 if (cs->condpart && cs->condpart->type == Xbinode &&
4605 cast(binode, cs->condpart)->op == Block) {
4610 print_exec(cs->condpart, indent+1, bracket);
4612 do_indent(indent, "}\n");
4614 do_indent(indent, "then\n");
4615 print_exec(cs->thenpart, indent+1, bracket);
4619 print_exec(cs->condpart, 0, bracket);
4625 print_exec(cs->thenpart, indent+1, bracket);
4627 do_indent(indent, "}\n");
4632 for (cp = cs->casepart; cp; cp = cp->next) {
4633 do_indent(indent, "case ");
4634 print_exec(cp->value, -1, 0);
4639 print_exec(cp->action, indent+1, bracket);
4641 do_indent(indent, "}\n");
4644 do_indent(indent, "else");
4649 print_exec(cs->elsepart, indent+1, bracket);
4651 do_indent(indent, "}\n");
4656 ###### propagate binode cases
4658 t = propagate_types(b->right, c, ok, Tnone, 0);
4659 if (!type_compat(Tnone, t, 0))
4660 *ok = 0; // UNTESTED
4661 return propagate_types(b->left, c, ok, type, rules);
4663 ###### propagate exec cases
4664 case Xcond_statement:
4666 // forpart and looppart->right must return Tnone
4667 // thenpart must return Tnone if there is a loopart,
4668 // otherwise it is like elsepart.
4670 // be bool if there is no casepart
4671 // match casepart->values if there is a switchpart
4672 // either be bool or match casepart->value if there
4674 // elsepart and casepart->action must match the return type
4675 // expected of this statement.
4676 struct cond_statement *cs = cast(cond_statement, prog);
4677 struct casepart *cp;
4679 t = propagate_types(cs->forpart, c, ok, Tnone, 0);
4680 if (!type_compat(Tnone, t, 0))
4681 *ok = 0; // UNTESTED
4684 t = propagate_types(cs->thenpart, c, ok, Tnone, 0);
4685 if (!type_compat(Tnone, t, 0))
4686 *ok = 0; // UNTESTED
4688 if (cs->casepart == NULL) {
4689 propagate_types(cs->condpart, c, ok, Tbool, 0);
4690 propagate_types(cs->looppart, c, ok, Tbool, 0);
4692 /* Condpart must match case values, with bool permitted */
4694 for (cp = cs->casepart;
4695 cp && !t; cp = cp->next)
4696 t = propagate_types(cp->value, c, ok, NULL, 0);
4697 if (!t && cs->condpart)
4698 t = propagate_types(cs->condpart, c, ok, NULL, Rboolok); // UNTESTED
4699 if (!t && cs->looppart)
4700 t = propagate_types(cs->looppart, c, ok, NULL, Rboolok); // UNTESTED
4701 // Now we have a type (I hope) push it down
4703 for (cp = cs->casepart; cp; cp = cp->next)
4704 propagate_types(cp->value, c, ok, t, 0);
4705 propagate_types(cs->condpart, c, ok, t, Rboolok);
4706 propagate_types(cs->looppart, c, ok, t, Rboolok);
4709 // (if)then, else, and case parts must return expected type.
4710 if (!cs->looppart && !type)
4711 type = propagate_types(cs->thenpart, c, ok, NULL, rules);
4713 type = propagate_types(cs->elsepart, c, ok, NULL, rules);
4714 for (cp = cs->casepart;
4716 cp = cp->next) // UNTESTED
4717 type = propagate_types(cp->action, c, ok, NULL, rules); // UNTESTED
4720 propagate_types(cs->thenpart, c, ok, type, rules);
4721 propagate_types(cs->elsepart, c, ok, type, rules);
4722 for (cp = cs->casepart; cp ; cp = cp->next)
4723 propagate_types(cp->action, c, ok, type, rules);
4729 ###### interp binode cases
4731 // This just performs one iterration of the loop
4732 rv = interp_exec(c, b->left, &rvtype);
4733 if (rvtype == Tnone ||
4734 (rvtype == Tbool && rv.bool != 0))
4735 // rvtype is Tnone or Tbool, doesn't need to be freed
4736 interp_exec(c, b->right, NULL);
4739 ###### interp exec cases
4740 case Xcond_statement:
4742 struct value v, cnd;
4743 struct type *vtype, *cndtype;
4744 struct casepart *cp;
4745 struct cond_statement *cs = cast(cond_statement, e);
4748 interp_exec(c, cs->forpart, NULL);
4750 while ((cnd = interp_exec(c, cs->looppart, &cndtype)),
4751 cndtype == Tnone || (cndtype == Tbool && cnd.bool != 0))
4752 interp_exec(c, cs->thenpart, NULL);
4754 cnd = interp_exec(c, cs->condpart, &cndtype);
4755 if ((cndtype == Tnone ||
4756 (cndtype == Tbool && cnd.bool != 0))) {
4757 // cnd is Tnone or Tbool, doesn't need to be freed
4758 rv = interp_exec(c, cs->thenpart, &rvtype);
4759 // skip else (and cases)
4763 for (cp = cs->casepart; cp; cp = cp->next) {
4764 v = interp_exec(c, cp->value, &vtype);
4765 if (value_cmp(cndtype, vtype, &v, &cnd) == 0) {
4766 free_value(vtype, &v);
4767 free_value(cndtype, &cnd);
4768 rv = interp_exec(c, cp->action, &rvtype);
4771 free_value(vtype, &v);
4773 free_value(cndtype, &cnd);
4775 rv = interp_exec(c, cs->elsepart, &rvtype);
4782 ### Top level structure
4784 All the language elements so far can be used in various places. Now
4785 it is time to clarify what those places are.
4787 At the top level of a file there will be a number of declarations.
4788 Many of the things that can be declared haven't been described yet,
4789 such as functions, procedures, imports, and probably more.
4790 For now there are two sorts of things that can appear at the top
4791 level. They are predefined constants, `struct` types, and the `main`
4792 function. While the syntax will allow the `main` function to appear
4793 multiple times, that will trigger an error if it is actually attempted.
4795 The various declarations do not return anything. They store the
4796 various declarations in the parse context.
4798 ###### Parser: grammar
4801 Ocean -> OptNL DeclarationList
4803 ## declare terminals
4811 DeclarationList -> Declaration
4812 | DeclarationList Declaration
4814 Declaration -> ERROR Newlines ${
4815 tok_err(c, // UNTESTED
4816 "error: unhandled parse error", &$1);
4822 ## top level grammar
4826 ### The `const` section
4828 As well as being defined in with the code that uses them, constants
4829 can be declared at the top level. These have full-file scope, so they
4830 are always `InScope`. The value of a top level constant can be given
4831 as an expression, and this is evaluated immediately rather than in the
4832 later interpretation stage. Once we add functions to the language, we
4833 will need rules concern which, if any, can be used to define a top
4836 Constants are defined in a section that starts with the reserved word
4837 `const` and then has a block with a list of assignment statements.
4838 For syntactic consistency, these must use the double-colon syntax to
4839 make it clear that they are constants. Type can also be given: if
4840 not, the type will be determined during analysis, as with other
4843 As the types constants are inserted at the head of a list, printing
4844 them in the same order that they were read is not straight forward.
4845 We take a quadratic approach here and count the number of constants
4846 (variables of depth 0), then count down from there, each time
4847 searching through for the Nth constant for decreasing N.
4849 ###### top level grammar
4853 DeclareConstant -> const { IN OptNL ConstList OUT OptNL } Newlines
4854 | const { SimpleConstList } Newlines
4855 | const IN OptNL ConstList OUT Newlines
4856 | const SimpleConstList Newlines
4858 ConstList -> ConstList SimpleConstLine
4861 SimpleConstList -> SimpleConstList ; Const
4865 SimpleConstLine -> SimpleConstList Newlines
4866 | ERROR Newlines ${ tok_err(c, "Syntax error in constant", &$1); }$
4869 CType -> Type ${ $0 = $<1; }$
4873 Const -> IDENTIFIER :: CType = Expression ${ {
4877 v = var_decl(c, $1.txt);
4879 struct var *var = new_pos(var, $1);
4880 v->where_decl = var;
4886 struct variable *vorig = var_ref(c, $1.txt);
4887 tok_err(c, "error: name already declared", &$1);
4888 type_err(c, "info: this is where '%v' was first declared",
4889 vorig->where_decl, NULL, 0, NULL);
4893 propagate_types($5, c, &ok, $3, 0);
4898 struct value res = interp_exec(c, $5, &v->type);
4899 global_alloc(c, v->type, v, &res);
4903 ###### print const decls
4908 while (target != 0) {
4910 for (v = context.in_scope; v; v=v->in_scope)
4911 if (v->depth == 0 && v->constant) {
4922 struct value *val = var_value(&context, v);
4923 printf(" %.*s :: ", v->name->name.len, v->name->name.txt);
4924 type_print(v->type, stdout);
4926 if (v->type == Tstr)
4928 print_value(v->type, val, stdout);
4929 if (v->type == Tstr)
4937 ### Function declarations
4939 The code in an Ocean program is all stored in function declarations.
4940 One of the functions must be named `main` and it must accept an array of
4941 strings as a parameter - the command line arguments.
4943 As this is the top level, several things are handled a bit differently.
4944 The function is not interpreted by `interp_exec` as that isn't passed
4945 the argument list which the program requires. Similarly type analysis
4946 is a bit more interesting at this level.
4948 ###### ast functions
4950 static struct type *handle_results(struct parse_context *c,
4951 struct binode *results)
4953 /* Create a 'struct' type from the results list, which
4954 * is a list for 'struct var'
4956 struct type *t = add_anon_type(c, &structure_prototype,
4957 " function result");
4961 for (b = results; b; b = cast(binode, b->right))
4963 t->structure.nfields = cnt;
4964 t->structure.fields = calloc(cnt, sizeof(struct field));
4966 for (b = results; b; b = cast(binode, b->right)) {
4967 struct var *v = cast(var, b->left);
4968 struct field *f = &t->structure.fields[cnt++];
4969 int a = v->var->type->align;
4970 f->name = v->var->name->name;
4971 f->type = v->var->type;
4973 f->offset = t->size;
4974 v->var->frame_pos = f->offset;
4975 t->size += ((f->type->size - 1) | (a-1)) + 1;
4978 variable_unlink_exec(v->var);
4980 free_binode(results);
4984 static struct variable *declare_function(struct parse_context *c,
4985 struct variable *name,
4986 struct binode *args,
4988 struct binode *results,
4992 struct value fn = {.function = code};
4994 var_block_close(c, CloseFunction, code);
4995 t = add_anon_type(c, &function_prototype,
4996 "func %.*s", name->name->name.len,
4997 name->name->name.txt);
4999 t->function.params = reorder_bilist(args);
5001 ret = handle_results(c, reorder_bilist(results));
5002 t->function.inline_result = 1;
5003 t->function.local_size = ret->size;
5005 t->function.return_type = ret;
5006 global_alloc(c, t, name, &fn);
5007 name->type->function.scope = c->out_scope;
5012 var_block_close(c, CloseFunction, NULL);
5014 c->out_scope = NULL;
5018 ###### declare terminals
5021 ###### top level grammar
5024 DeclareFunction -> func FuncName ( OpenScope ArgsLine ) Block Newlines ${
5025 $0 = declare_function(c, $<FN, $<Ar, Tnone, NULL, $<Bl);
5027 | func FuncName IN OpenScope Args OUT OptNL do Block Newlines ${
5028 $0 = declare_function(c, $<FN, $<Ar, Tnone, NULL, $<Bl);
5030 | func FuncName NEWLINE OpenScope OptNL do Block Newlines ${
5031 $0 = declare_function(c, $<FN, NULL, Tnone, NULL, $<Bl);
5033 | func FuncName ( OpenScope ArgsLine ) : Type Block Newlines ${
5034 $0 = declare_function(c, $<FN, $<Ar, $<Ty, NULL, $<Bl);
5036 | func FuncName ( OpenScope ArgsLine ) : ( ArgsLine ) Block Newlines ${
5037 $0 = declare_function(c, $<FN, $<AL, NULL, $<AL2, $<Bl);
5039 | func FuncName IN OpenScope Args OUT OptNL return Type Newlines do Block Newlines ${
5040 $0 = declare_function(c, $<FN, $<Ar, $<Ty, NULL, $<Bl);
5042 | func FuncName NEWLINE OpenScope return Type Newlines do Block Newlines ${
5043 $0 = declare_function(c, $<FN, NULL, $<Ty, NULL, $<Bl);
5045 | func FuncName IN OpenScope Args OUT OptNL return IN Args OUT OptNL do Block Newlines ${
5046 $0 = declare_function(c, $<FN, $<Ar, NULL, $<Ar2, $<Bl);
5048 | func FuncName NEWLINE OpenScope return IN Args OUT OptNL do Block Newlines ${
5049 $0 = declare_function(c, $<FN, NULL, NULL, $<Ar, $<Bl);
5052 ###### print func decls
5057 while (target != 0) {
5059 for (v = context.in_scope; v; v=v->in_scope)
5060 if (v->depth == 0 && v->type && v->type->check_args) {
5069 struct value *val = var_value(&context, v);
5070 printf("func %.*s", v->name->name.len, v->name->name.txt);
5071 v->type->print_type_decl(v->type, stdout);
5073 print_exec(val->function, 0, brackets);
5075 print_value(v->type, val, stdout);
5076 printf("/* frame size %d */\n", v->type->function.local_size);
5082 ###### core functions
5084 static int analyse_funcs(struct parse_context *c)
5088 for (v = c->in_scope; v; v = v->in_scope) {
5092 if (v->depth != 0 || !v->type || !v->type->check_args)
5094 ret = v->type->function.inline_result ?
5095 Tnone : v->type->function.return_type;
5096 val = var_value(c, v);
5099 propagate_types(val->function, c, &ok, ret, 0);
5102 /* Make sure everything is still consistent */
5103 propagate_types(val->function, c, &ok, ret, 0);
5106 if (!v->type->function.inline_result &&
5107 !v->type->function.return_type->dup) {
5108 type_err(c, "error: function cannot return value of type %1",
5109 v->where_decl, v->type->function.return_type, 0, NULL);
5112 scope_finalize(c, v->type);
5117 static int analyse_main(struct type *type, struct parse_context *c)
5119 struct binode *bp = type->function.params;
5123 struct type *argv_type;
5125 argv_type = add_anon_type(c, &array_prototype, "argv");
5126 argv_type->array.member = Tstr;
5127 argv_type->array.unspec = 1;
5129 for (b = bp; b; b = cast(binode, b->right)) {
5133 propagate_types(b->left, c, &ok, argv_type, 0);
5135 default: /* invalid */ // NOTEST
5136 propagate_types(b->left, c, &ok, Tnone, 0); // NOTEST
5142 return !c->parse_error;
5145 static void interp_main(struct parse_context *c, int argc, char **argv)
5147 struct value *progp = NULL;
5148 struct text main_name = { "main", 4 };
5149 struct variable *mainv;
5155 mainv = var_ref(c, main_name);
5157 progp = var_value(c, mainv);
5158 if (!progp || !progp->function) {
5159 fprintf(stderr, "oceani: no main function found.\n");
5163 if (!analyse_main(mainv->type, c)) {
5164 fprintf(stderr, "oceani: main has wrong type.\n");
5168 al = mainv->type->function.params;
5170 c->local_size = mainv->type->function.local_size;
5171 c->local = calloc(1, c->local_size);
5173 struct var *v = cast(var, al->left);
5174 struct value *vl = var_value(c, v->var);
5184 mpq_set_ui(argcq, argc, 1);
5185 memcpy(var_value(c, t->array.vsize), &argcq, sizeof(argcq));
5186 t->prepare_type(c, t, 0);
5187 array_init(v->var->type, vl);
5188 for (i = 0; i < argc; i++) {
5189 struct value *vl2 = vl->array + i * v->var->type->array.member->size;
5191 arg.str.txt = argv[i];
5192 arg.str.len = strlen(argv[i]);
5193 free_value(Tstr, vl2);
5194 dup_value(Tstr, &arg, vl2);
5198 al = cast(binode, al->right);
5200 v = interp_exec(c, progp->function, &vtype);
5201 free_value(vtype, &v);
5206 ###### ast functions
5207 void free_variable(struct variable *v)
5211 ## And now to test it out.
5213 Having a language requires having a "hello world" program. I'll
5214 provide a little more than that: a program that prints "Hello world"
5215 finds the GCD of two numbers, prints the first few elements of
5216 Fibonacci, performs a binary search for a number, and a few other
5217 things which will likely grow as the languages grows.
5219 ###### File: oceani.mk
5222 @echo "===== DEMO ====="
5223 ./oceani --section "demo: hello" oceani.mdc 55 33
5229 four ::= 2 + 2 ; five ::= 10/2
5230 const pie ::= "I like Pie";
5231 cake ::= "The cake is"
5239 func main(argv:[argc::]string)
5240 print "Hello World, what lovely oceans you have!"
5241 print "Are there", five, "?"
5242 print pi, pie, "but", cake
5244 A := $argv[1]; B := $argv[2]
5246 /* When a variable is defined in both branches of an 'if',
5247 * and used afterwards, the variables are merged.
5253 print "Is", A, "bigger than", B,"? ", bigger
5254 /* If a variable is not used after the 'if', no
5255 * merge happens, so types can be different
5258 double:string = "yes"
5259 print A, "is more than twice", B, "?", double
5262 print "double", B, "is", double
5267 if a > 0 and then b > 0:
5273 print "GCD of", A, "and", B,"is", a
5275 print a, "is not positive, cannot calculate GCD"
5277 print b, "is not positive, cannot calculate GCD"
5282 print "Fibonacci:", f1,f2,
5283 then togo = togo - 1
5291 /* Binary search... */
5296 mid := (lo + hi) / 2
5309 print "Yay, I found", target
5311 print "Closest I found was", lo
5316 // "middle square" PRNG. Not particularly good, but one my
5317 // Dad taught me - the first one I ever heard of.
5318 for i:=1; then i = i + 1; while i < size:
5319 n := list[i-1] * list[i-1]
5320 list[i] = (n / 100) % 10 000
5322 print "Before sort:",
5323 for i:=0; then i = i + 1; while i < size:
5327 for i := 1; then i=i+1; while i < size:
5328 for j:=i-1; then j=j-1; while j >= 0:
5329 if list[j] > list[j+1]:
5333 print " After sort:",
5334 for i:=0; then i = i + 1; while i < size:
5338 if 1 == 2 then print "yes"; else print "no"
5342 bob.alive = (bob.name == "Hello")
5343 print "bob", "is" if bob.alive else "isn't", "alive"