1 files changed, 39 insertions, 0 deletions
diff --git a/store/works/life/compile-principle-experiment/4/syn.y b/store/works/life/compile-principle-experiment/4/syn.y
new file mode 100644
index 0000000..ebe113f
--- /dev/null
+++ b/store/works/life/compile-principle-experiment/4/syn.y
@@ -0,0 +1,39 @@
+%{
+#include "main.h"
+#include <stdio.h>
+#define	code2(c1,c2)	code(c1); code(c2)
+#define	code3(c1,c2,c3)	code(c1); code(c2); code(c3)
+%}
+%union {
+	Symbol	*sym;	/* symbol table pointer */
+	double val;
+	Inst	*inst;	/* machine instruction */
+}
+%token	<sym>	NUMBER VAR BLTIN UNDEF
+%right	'='
+%left	'+' '-'
+%left	'*' '/'
+%left	UNARYMINUS
+%right	'^'	/* exponentiation */
+%%
+list:	  /* nothing */
+	| list '\n'
+	| list asgn '\n'  { code2(mypop, STOP); return 1; }
+	| list expr '\n'  { code2(print, STOP); return 1; }
+	| list error '\n' { yyerrok; }
+	;
+asgn:	  VAR '=' expr	{ code3(varpush,(Inst)$1,assign); }
+	;
+expr:	  NUMBER	{ code2(constpush, (Inst)$1); }
+	| VAR		{ code3(varpush, (Inst)$1, eval); }
+	| asgn
+	| BLTIN '(' expr ')' { code2(bltin, (Inst)$1->value.ptr); }
+	| '(' expr ')'
+	| expr '+' expr	{ code(add); }
+	| expr '-' expr	{ code(sub); }
+	| expr '*' expr	{ code(mul); }
+	| expr '/' expr	{ code(mydiv); }
+	| expr '^' expr	{ code(power); }
+	| '-' expr  %prec UNARYMINUS  { code(negate); }
+	;
+%%