initial compiler work.

1 files changed, 213 insertions, 0 deletions

diff --git a/semblance.y b/semblance.y
new file mode 100644
index 0000000..c6629a1
--- /dev/null
+++ b/semblance.y
@@ -0,0 +1,213 @@
+%{
+#include <u.h>
+#include <libc.h>
+#include <ctype.h>
+#include <bio.h>
+#include <geometry.h>
+#include "dat.h"
+#include "fns.h"
+%}
+%union {
+	int type;
+	double val;
+	Symbol *sym;
+}
+%token	<type> TYPE
+%token	<val> NUMBER
+%token	<sym> VAR CONST BLTIN UNDEF
+%type	<val> expr exprs
+%type	<sym> asgn asgns
+%right	'='
+%%
+top:	/* ε */
+	| list
+	;
+list:	  prog
+	| list prog
+	;
+prog:	'\n'
+	| decls
+	| asgns
+	| exprs			{ print("\t%.8g\n", $1); }
+	;
+decls:	  decls decl
+	| decl
+	;
+decl:	  TYPE { decltype = $1; } vars ';'
+	;
+vars:	  VAR
+	{
+		if($1->type != UNDEF)
+			rterror("variable already exists");
+
+		$1->type = VAR;
+		$1->u.var.type = decltype;
+		print("%s %s;\n", ctypename(decltype), $1->name);
+	}
+	| vars ',' VAR
+	{
+		if($3->type != UNDEF)
+			rterror("variable already exists");
+
+		$3->type = VAR;
+		$3->u.var.type = decltype;
+		print("%s %s;\n", ctypename(decltype), $3->name);
+	}
+	;
+asgns:	  asgns asgn ';'
+	| asgn ';'
+	;
+asgn:	 VAR '=' NUMBER
+	{
+		if($1->type != VAR || $1->u.var.type != TDOUBLE)
+			rterror("illegal assignment");
+
+		$1->u.var.dval = $3;
+		$$ = $1;
+	}
+	| VAR '=' VAR
+	{
+		switch($1->type){
+		default: rterror("illegal assignment");
+		case VAR:
+			if($1->u.var.type != $3->u.var.type)
+				rterror("illegal assignment");
+
+			switch($1->u.var.type){
+			case TDOUBLE:
+				$1->u.var.dval = $3->u.var.dval;
+				break;
+			case TPOINT:
+			case TVECTOR:
+			case TNORMAL:
+			case TQUAT:
+				$1->u.var.pval = $3->u.var.pval;
+				break;
+			}
+			$$ = $1;
+			break;
+		}
+	}
+	;
+exprs:	  exprs expr ';'
+	| expr ';'
+	;
+expr:	  NUMBER
+	| VAR
+	{
+		Point3 *p;
+
+		switch($1->type){
+		case UNDEF: rterror("undefined variable");
+		case CONST: $$ = $1->u.val; break;
+		case VAR:
+			switch($1->u.var.type){
+			case TDOUBLE: $$ = $1->u.var.dval; break;
+			case TPOINT:
+			case TVECTOR:
+			case TNORMAL:
+				$$ = -1;
+				p = &$1->u.var.pval;
+				print("[%g %g %g %g]\n", p->x, p->y, p->z, p->w);
+				break;
+			}
+			break;
+		}
+	}
+	;
+%%
+
+int decltype;
+Biobuf *bin;
+int lineno;
+
+void
+yyerror(char *msg)
+{
+	fprint(2, "%s at line %d\n", msg, lineno);
+}
+
+void
+rterror(char *msg)
+{
+	fprint(2, "%s at line %d\n", msg, lineno);
+}
+
+int
+yylex(void)
+{
+	Symbol *s;
+	char sname[256], *p;
+	Rune r;
+	int t;
+
+	while((r = Bgetrune(bin)) == ' ' || r == '\t')
+		;
+
+	if(r == Beof)
+		return 0;
+
+	if(r == '.' || isdigitrune(r)){
+		Bungetrune(bin);
+		Bgetd(bin, &yylval.val);
+		return NUMBER;
+	}
+
+	if(isalpharune(r)){
+		p = sname;
+
+		do{
+			if(p+runelen(r) - sname >= sizeof(sname))
+				return r; /* force syntax error. */
+			p += runetochar(p, &r);
+		}while((r = Bgetrune(bin)) != Beof &&
+			(isalpharune(r) || isdigitrune(r)));
+		Bungetrune(bin);
+		*p = 0;
+
+		if((t = lookuptype(sname)) >= 0){
+			yylval.type = t;
+			return TYPE;
+		}
+
+		if((s = lookup(sname)) == nil)
+			s = install(sname, UNDEF, 0);
+		yylval.sym = s;
+
+		return s->type == UNDEF || s->type == CONST ? VAR : s->type;
+	}
+
+	if(r == '\n')
+		lineno++;
+
+	return r;
+}
+
+void
+usage(void)
+{
+	fprint(2, "usage: %s\n", argv0);
+	exits("usage");
+}
+
+void
+main(int argc, char *argv[])
+{
+	ARGBEGIN{
+	default: usage();
+	}ARGEND;
+	if(argc > 0)
+		usage();
+
+	bin = Bfdopen(0, OREAD);
+	if(bin == nil)
+		sysfatal("Bfdopen: %r");
+
+	lineno++;
+	init();
+
+	yyparse();
+
+	Bterm(bin);
+	exits(nil);
+}