词法分析器.cpp

编译原理的词法分析器源代码

#include "stack.h"
#include<string.h>
const  int maxsize=500;//输入程序的总容量
const  int retainsize=30;//最大单词的长度
void  main()
{
	stack  sretain,snum,sidentier,sresult;
	  char  input[maxsize],word[retainsize];
	    int num=0,flag,quanlity;
	      cout<<"请输入基本字的个数!"<<endl;
		   cin>>quanlity;
		    for(int j=0;j<quanlity;j++)
			{
				cout<<"第"<<j+1<<"个基本字: ";
				  cin>>word;
				    if(sretain.compare(word,strlen(word))==-1)
				      sretain.pushretain(word,strlen(word));
			}
		  cout<<"请输入程序段,以'!'结束!"<<endl;
		   cin.unsetf(ios::skipws);
		    cin>>input[num];
			  while(input[num]!='!'&&num<maxsize)
			  {
				  num++;
				   cin>>input[num];
			  }
        for(int i=0;i<num;)
		{   
				flag=0;
				 if(input[i]=='+'||input[i]=='='||input[i]==','||input[i]=='('||input[i]==')')
				 {
					word[flag]=input[i];
					flag++;
					int temp=sretain.compare(word,flag);
					if(temp==-1)
				    	temp=sretain.pushretain(word,flag);
					sresult.push(word,flag,temp,-1);
					i++;
				}
				 else
					 if(input[i]>='0'&&input[i]<='9')
					 {
						 word[flag]=input[i];
						 flag++;
						 i++;
						 while(input[i]>='0'&&input[i]<='9')
						 {
							 word[flag]=input[i];
							 flag++;
							 i++;
						 }
						 int temp=snum.compare(word,flag);
						 if(temp==-1)
						    temp=snum.pushnum(word,flag);
							sresult.push(word,flag,7,temp);
					 }
					 else
						 if(input[i]>='A'&&input[i]<='Z'||input[i]>='a'&&input[i]<='z')
						 {
							 word[flag]=input[i];
							 flag++;
							 i++;
							 while(input[i]>='A'&&input[i]<='Z'||input[i]>='a'&&input[i]<='z'||input[i]>='0'&&input[i]<='9')
							 {
								 word[flag]=input[i];
								 flag++;
								 i++;
							 }
							 int temp=sretain.compare(word,flag);
						      if(temp!=-1)
								  sresult.push(word,flag,temp,-1);
							    else
								{
									temp=sidentier.compare(word,flag);
									if(temp==-1)
										temp=sidentier.pushvar(word,flag,0);
									sresult.push(word,flag,6,temp);
								}
						 }
						 else
							 if(input[i]=='*')
							 {
								 word[flag]=input[i];
								 flag++;
								 i++;
								 if(input[i]=='*')
								 {
									 word[flag]=input[i];
									 flag++;
									 i++;
								 }
								 int temp=sretain.compare(word,flag);
								 if(temp==-1)
									 temp=sretain.pushretain(word,flag);
								 sresult.push(word,flag,temp,-1);
							 }
							 else 
								 if(input[i]=='#'||input[i]=='@')//定义非法字符
								 {
								 word[flag]=input[i];
								 flag++;
								 i++;
								 sresult.pushvar(word,flag,1);
								 }
								 else
									 i++;
		}
		cout<<"下面是你输入的基本字:"<<endl;
		  sretain.show(0);
		    cout<<endl;
			 cout<<"下面是标志符:"<<endl;
			  sidentier.show(0);
			   cout<<endl;
			     cout<<"下面是常数:"<<endl;
				  snum.show(0);
					  cout<<endl;
				   cout<<"下面是你输入对应的结果:"<<endl;
				     for(i=0;i<num;i++)
						 cout<<input[i];
					   cout<<endl;
				       sresult.show(1);
						   cout<<endl;
						    cin>>i;
}