parse.c

参照清华大学《编译原理》写的cmm语言语法分析程序

/** 
 * @file parse.c
 * @brief  语法分析器的实现
 * @author Shiquan Ye, [e-mail]
 * @date 2008-11-13
 */
/*
 * Copyright (C) 2008 - Shiquan Ye, [e-mail]
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */

#include "globals.h"
#include "util.h"
#include "scan.h"
#include "parse.h"

static TokenType token;                         /* 保存当前的token */


TreeNode * var_dec();
TreeNode * program(); 

/** 
 * @brief  打印语法错误的提示信息
 * 
 * @param message 
 */
static void syntaxError(char * message) {
      fprintf(listing,"\n>>>");
      fprintf(listing,"Syntax error at line %d: %s",lineno,message);
      Error = TRUE;
}

/** 
 * @brief  检查当前token是否是期望的token,如果是会获取下一个token
 * 
 * @param expected 
 */
static void match(TokenType expected) {
      if (token == expected) token = getToken();
      else {
            syntaxError("unexpected token -->");
            printToken(token,tokenString);
            fprintf(listing,"        ");
      }
}

/** 
 * @brief  打印token的类型和对应的string
 * 
 * @param token 
 * @param tokenString 
 */
void printToken(TokenType token, const char * tokenString) {
      printf("%s\n",tokenString);
}

/** 
 * @brief  语法分析函数
 * 
 * @returns 新生成的语法树
 */
TreeNode * parse(void) {
      TreeNode * t;
      token = getToken();
      t = program();
      if (token != ENDFILE) {
            syntaxError("Code ends before file\n");
      }
      return t;
}

TreeNode * program() {
      TreeNode * t;
      t = var_dec();
      return t;
}


TreeNode * var_dec() {
      TreeNode * t = newStmtNode(VarDecK);
      if (token == INT) {
            t->child[0] = newOneTokenNode(IntK);
            t->child[0]->attr.type = INT;
      }
      else if (token == REAL) {
            t->child[0] = newOneTokenNode(RealK);
            t->child[0]->attr.type = REAL;
      }
      else {
            syntaxError("unexpected token -> ");
            printToken(token,tokenString);
      }
      token = getToken();
      match(ID);
      if (token = LBRACKET) token = getToken();
      match(RBRACKET);
      match(ASSIGN);

      t->child[2] = var_init();
}

TreeNode * var_id() {
      TreeNode * t = newVarIdNode();
}

TreeNode * var_init() {
}

TreeNode * array_init() {
}

TreeNode * exp() {
}

TreeNode * item() {
}

TreeNode * factor() {
}