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%{
#include <stdio.h>
#include "ast.h"
extern char *yytext;
extern int yylineno;
extern int yylex();
ASTNode *ast_root;
void yyerror(const char *s) {
fprintf(stderr, "Parse error at token \"%s\", line %d: %s\n", yytext, yylineno, s);
}
%}
%union {
int num;
char *id;
struct ASTNode *node;
}
%start prog
%token <num> T_NUM
%token <id> T_ID
%token T_EQ T_NE T_LT T_LE T_GT T_GE
%token T_TRUE T_FALSE
%left T_OR
%left T_AND
%token T_NOT
%left T_PLUS T_MINUS
%left T_STAR
%right T_UMINUS
%token T_END T_IF T_THEN T_ELSE T_WHILE T_DO T_VAR T_IN
%token T_SKIP
%token T_ASSIGN
%token T_LPAREN T_RPAREN
%token T_SEM
%type <node> prog stm var aexp bexp
%%
prog : stm
{ ast_root = $1; }
;
stm : T_SKIP
{ $$ = ast_skip(); }
| var T_ASSIGN aexp
{ $$ = ast_assign($1, $3); }
| T_LPAREN stm T_SEM stm T_RPAREN
{ $$ = ast_seq($2, $4); }
| stm T_SEM stm
{ $$ = ast_seq($1, $3); }
| stm T_SEM
{ $$ = $1; }
| T_IF bexp T_THEN stm T_ELSE stm T_END
{ $$ = ast_if($2, $4, $6); }
| T_IF bexp T_THEN stm T_END
{ $$ = ast_if($2, $4, ast_skip()); }
| T_WHILE bexp T_DO stm T_END
{ $$ = ast_while($2, $4); }
| T_VAR var T_ASSIGN aexp T_IN stm T_END
{ $$ = ast_let($2, $4, $6); }
;
var : T_ID
{ $$ = ast_var($1); }
;
aexp : aexp T_PLUS aexp
{ $$ = ast_aop(AOP_ADD, $1, $3); }
| aexp T_MINUS aexp
{ $$ = ast_aop(AOP_SUB, $1, $3); }
| aexp T_STAR aexp
{ $$ = ast_aop(AOP_MUL, $1, $3); }
| T_MINUS aexp %prec T_UMINUS
{ $$ = ast_aop(AOP_SUB, ast_int(0), $2); }
| T_LPAREN aexp T_RPAREN
{ $$ = $2; }
| var
{ $$ = $1; }
| T_NUM
{ $$ = ast_int($1); }
;
bexp : bexp T_OR bexp
{ $$ = ast_bop(BOP_OR, $1, $3); }
| bexp T_AND bexp
{ $$ = ast_bop(BOP_AND, $1, $3); }
| T_NOT bexp
{ $$ = ast_not($2); }
| aexp T_EQ aexp
{ $$ = ast_rop(ROP_EQ, $1, $3); }
| aexp T_NE aexp
{ $$ = ast_rop(ROP_NE, $1, $3); }
| aexp T_LE aexp
{ $$ = ast_rop(ROP_LE, $1, $3); }
| aexp T_LT aexp
{ $$ = ast_rop(ROP_LT, $1, $3); }
| aexp T_GE aexp
{ $$ = ast_rop(ROP_GE, $1, $3); }
| aexp T_GT aexp
{ $$ = ast_rop(ROP_GT, $1, $3); }
| T_LPAREN bexp T_RPAREN
{ $$ = $2; }
| T_TRUE
{ $$ = ast_rop(ROP_EQ, ast_int(1), ast_int(1)); }
| T_FALSE
{ $$ = ast_rop(ROP_EQ, ast_int(0), ast_int(1)); }
;
%%
|
