analyser.cpp

LL1通用语法分析器

/************************************************************************
                        Copyright IBMTC Written by Xinxi Wang
**************************************************************************/

#include <iostream>
#include "Analyser.h"
#include "Terminal.h"
#include "Variable.h"
#include "Epsilon.h"

using namespace std;

Analyser::Analyser(AnalyzeTable &table, Syntax *s) 
    : analyzeTable(table), syntax(s)
{
    Token *p = new Terminal("$");
    pool.push_back(p);
    tokenStack.push(p);
    
    //加入起始变元
    p = s->getStartVariable().clone();
    pool.push_back(p);
    tokenStack.push(p);
}


/**
 * @brief 分析
 */
void Analyser::analyze ( )
{
    Lexer * lexer = Lexer::getInstance();
    
    while(!tokenStack.empty())
    {
        switch(tokenStack.top()->getType())
        {
            case TERMINAL:

                if(lexer->nextToken() == *tokenStack.top())
                {
#ifdef DEBUG
                    cout << "匹配终结符: ";
                    tokenStack.top()->print();
                    cout << endl;
#endif                    

                    if(*tokenStack.top() == Terminal("$"))
                        cout << "分析成功" << endl;

                    tokenStack.pop();
                } else
                    error("栈顶终结符与缓冲区不匹配");
                
                break;
                
            case VARIABLE:
            {
                Index idx(dynamic_cast<Variable &>(*tokenStack.top()), lexer->current());
                
                Pattern pattern;
                try{
                    pattern = analyzeTable.getProduction(idx).getRhs();
                }catch (ProductionNotExists & e){
                    error("无匹配的产生式");
                }

#ifdef DEBUG                
                tokenStack.top()->print();
                cout << " 生成 ";
                pattern.print();
                cout << endl;
#endif    
                tokenStack.pop();
                
                for(int i = pattern.length() - 1; i >= 0; i--){
                    Token *p = pattern.at(i)->clone();
                    pool.push_back(p);
                    tokenStack.push(p);
                }

                break;
            }
            case EPSILON:
                tokenStack.pop();
                break;
        }
    }
}


/**
 * @brief 错误信息输出
 * @param  msg
 */
void Analyser::error (string msg )
{
    cerr.width(5);
    cerr << Lexer::getInstance()->line() << ": " << Lexer::getInstance()->getBuffer() << endl
         << string(Lexer::getInstance()->column() + 7, ' ') <<  '^' << endl
         << string(Lexer::getInstance()->column() + 7, ' ') << msg << endl;
    
    exit(1);
}


Analyser::~Analyser()
{
    for(int i = 0; i < pool.size(); i++){
        delete pool[i];
    }
}