}
t = selection_stmt(); break;
t = iteration_stmt(); break;
t = return_stmt(); break;
t = compound_stmt(); break;
t = expression_stmt(); break; syntaxError(\
currentToken = getToken(); break;
case WHILE:
case RETURN:
case LBBRACKET:
case ID: case SEMI: case LPAREN: case NUM:
default:
return t; }
TreeNode * Parser :: selection_stmt(void) {
TreeNode * t = newNode(Selection_StmtK); match(IF); match(LPAREN); if(t!=NULL) { }
match(RPAREN); t->child[1] = statement();
if(currentToken.tokenType==ELSE)
t->child[0] = expression();
{ } return t; }
TreeNode * Parser :: expression_stmt(void) {
TreeNode * t = NULL;
if(currentToken.tokenType==SEMI) { } else { } return t; }
TreeNode * Parser :: iteration_stmt(void) {
TreeNode * t = newNode(Iteration_StmtK); match(WHILE); match(LPAREN); if(t!=NULL) {
t->child[0] = expression(); t = expression(); match(SEMI); match(SEMI); return t; match(ELSE); if(t!=NULL) { }
t->child[2] = statement();
}
match(RPAREN); if(t!=NULL) { } return t; }
TreeNode * Parser :: return_stmt(void) {
TreeNode * t = newNode(Return_StmtK); match(RETURN);
if (currentToken.tokenType==SEMI) { } else { }
match(SEMI); return t; }
TreeNode * Parser :: expression(void) {
TreeNode * t = var();
if(t==NULL)//不是以ID开头，只能是simple_expression情况
if(t!=NULL) { }
t->child[0] = expression(); match(SEMI); return t;
t->child[1] = statement();
{ t = simple_expression(t);
}
else//以ID开头，可能是赋值语句，或simple_expression中的var和call类型的情况 { TreeNode * p = NULL;
if(currentToken.tokenType==ASSIGN)//赋值语句 { p = newNode(AssignK);
p->attr.name = lastToken.tokenString.c_str(); match(ASSIGN); p->child[0] = t;
p->child[1] = expression(); return p;
}
else //simple_expression中的var和call类型的情况 { t = simple_expression(t); } }
return t;
}
TreeNode * Parser :: simple_expression(TreeNode * k) {
TreeNode * t = additive_expression(k); k = NULL;
if(EQ==currentToken.tokenType || GT==currentToken.tokenType GEQ==currentToken.tokenType ||
LT==currentToken.tokenType
LEQ==currentToken.tokenType || NEQ==currentToken.tokenType)
{ TreeNode * q = newNode(OpK); q->attr.op = currentToken.tokenType;
q->child[0] = t;
|| ||
