cm_parse.y

小型编译系统的源代码

                      {
                        $$ = $1;
                      }
                    | return_stmt
                      {
                        $$ = $1;
                      }
                    ;
expression_stmt     : expression SEMICOLON
                      {
                        $$ = $1;
                      }
                    | SEMICOLON
                      {
                        $$ = 0;
                      }
                    ;
selection_stmt      : IF LPAREN expression RPAREN statement ELSE statement
                      {
                        $$ = newStmtNode(IfK);
                        $$->child[0] = $3;
                        $$->child[1] = $5;
                        $$->child[2] = $7;
                      }
                    | IF LPAREN expression RPAREN statement
                      {
                        $$ = newStmtNode(IfK);
                        $$->child[0] = $3;
                        $$->child[1] = $5;
                      }
                    ;
while_stmt          : WHILE LPAREN expression RPAREN statement
                      {
                        $$ = newStmtNode(WhileK);
                        $$->child[0] = $3;
                        $$->child[1] = $5;
                      }
                    ;
for_stmt            : FOR LPAREN for_expression SEMICOLON for_expression SEMICOLON for_expression RPAREN statement
                      {
                        $$ = newStmtNode(ForK);
                        $$->child[0] = $3;
                        $$->child[1] = $5;
                        $$->child[2] = $7;
                        $$->child[3] = $9;
                      }
                    ;
return_stmt         : RETURN SEMICOLON
                      {
                        $$ = newStmtNode(ReturnK);
                      }
                    | RETURN expression SEMICOLON
                      {
                        $$ = newStmtNode(ReturnK);
                        $$->child[0] = $2;
                      }
                    ;
expression          : var ASSIGN expression
                      {
                        $$ = newExpNode(OpK);
                        $$->attr.op = ASSIGN;
                        $$->child[0] = $1;
                        $$->child[1] = $3;
                      }
                    | or_expression
                      {
                        $$ = $1;
                      }
                    ;
for_expression      : var ASSIGN expression
                      {
                        $$ = newExpNode(OpK);
                        $$->attr.op = ASSIGN;
                        $$->child[0] = $1;
                        $$->child[1] = $3;
                      }
                    | or_expression
                      {
                        $$ = $1;
                      }
                    | empty
                    	{
                    		$$ = 0;
                    	}
                    ;
empty								:;
var                 : ID
                      {
                        $$ = newExpNode(IdK);
                        $$->lineno = lineno; 
                        $$->attr.name = copyString(tokenString);
                      }
                    | ID { $$ = newExpNode(ArrayK); $$->attr.name = copyString(tokenString); } LBRACKET expression RBRACKET
                      {
												$$ = newExpNode(ArrayK);
												$$->attr.name = $2->attr.name;
												delete($2);
                        $$->child[0] = $4; /*?*/
                      }
                    ;
or_expression       : or_expression OR and_expression
                      {
                        $$ = newExpNode(OpK);
                        $$->child[0] = $1;
                        $$->child[1] = $3;
                        $$->attr.op = OR;
                      }
                    | and_expression
                      { $$ = $1; }
                    ;
and_expression      : and_expression AND additive_expression
                      {
                        $$ = newExpNode(OpK);
                        $$->child[0] = $1;
                        $$->child[1] = $3;
                        $$->attr.op = AND;
                      }
                    | additive_expression
                      { $$ = $1; }
                    ;
additive_expression : additive_expression EQ rel_expression
											{
												$$ = newExpNode(OpK);
                        $$->child[0] = $1;
                        $$->child[1] = $3;
                        $$->attr.op = EQ;
											}
										| additive_expression LT rel_expression	
											{
												$$ = newExpNode(OpK);
                        $$->child[0] = $1;
                        $$->child[1] = $3;
                        $$->attr.op = LT;
											}
										| additive_expression GT rel_expression	
											{
												$$ = newExpNode(OpK);
                        $$->child[0] = $1;
                        $$->child[1] = $3;
                        $$->attr.op = GT;
											}
										| additive_expression LE rel_expression	
											{
												$$ = newExpNode(OpK);
                        $$->child[0] = $1;
                        $$->child[1] = $3;
                        $$->attr.op = LE;
											}
										| additive_expression GE rel_expression	
											{
												$$ = newExpNode(OpK);
                        $$->child[0] = $1;
                        $$->child[1] = $3;
                        $$->attr.op = GE;
											}
										| additive_expression NE rel_expression	
											{
												$$ = newExpNode(OpK);
                        $$->child[0] = $1;
                        $$->child[1] = $3;
                        $$->attr.op = NE;
											}
										| rel_expression
											{
												$$ = $1;
											}
										;
rel_expression : rel_expression PLUS term
                      {
                        $$ = newExpNode(OpK);
                        $$->child[0] = $1;
                        $$->child[1] = $3;
                        $$->attr.op = PLUS;
                      }
                    | rel_expression MINUS term
                      {
                        $$ = newExpNode(OpK);
                        $$->child[0] = $1;
                        $$->child[1] = $3;
                        $$->attr.op = MINUS;
                      }
                    | term
                      { $$ = $1; }
                    ;
term                : term TIMES factor
                      {
                        $$ = newExpNode(OpK);
                        $$->child[0] = $1;
                        $$->child[1] = $3;
                        $$->attr.op = TIMES;
                      }
                    | term OVER factor
                      {
                        $$ = newExpNode(OpK);
                        $$->child[0] = $1;
                        $$->child[1] = $3;
                        $$->attr.op = OVER;
                      }
                    | factor
                      { $$ = $1; }
                    ;
factor              : LPAREN expression RPAREN 
                      { $$ = $2; }
                    | var
                      { $$ = $1; }
                    | call
                      { $$ = $1; }
                    | NUM
                      { 
												$$ = newExpNode(ConstK);
                        $$->attr.vali = atoi(tokenString); 
                        $$->attr.vartype = Integer;
                      }
                    | FLOATNUM
                      {
                        $$ = newExpNode(ConstK);
                        $$->attr.valf = atof(tokenString); 
                        $$->attr.vartype = Float;
                      }
                    | CONSTCHAR
                    	{
                    		$$ = newExpNode(ConstK);
                        $$->attr.valch = tokenString[1];
                        $$->attr.vartype = Char;
                    	}
                    | NOT factor
                      { 
                        $$ = newExpNode(NotK);
                        $$->child[0] = $2;
                      }
                    ;
call                : id LPAREN arg_list RPAREN
                      {
                        $$ = newExpNode(CallK);
                        $$->child[0] = $1;
                        $$->child[1] = $3;
                      }
                    | id LPAREN RPAREN
                      {
                        $$ = newExpNode(CallK);
                        $$->child[0] = $1;
                      }
                    ;

arg_list            : expression COMMA arg_list
                      {
                        $$ = $1;
                        $$->sibling = $3;
                      }
                    | expression
                      {
                        $$ = $1;
                      }
                    ;
%%

void yyerror(const char * message)
{
  fprintf(listing,"Syntax error at line %d: %s\n",lineno,message);
  fprintf(listing,"Current token: ");
  printToken(yychar, tokenString);
  Error = TRUE;
}

/* yylex calls getToken to make Yacc/Bison output
 * compatible with ealier versions of the TINY scanner
 */
static int yylex(void)
{
  return getToken();
}

TreeNode * parse(void)
{ 
  yyparse();
  return savedTree;
}