编译原理实验词法分析语法分析

本代码只供学习参考：

词法分析源代码：

#include

#include

#include

using namespace std;

string key[8]={"do","end","for","if","printf","scanf","then","while"}; string optr[4]={"+","-","*","/"};

string separator[6]={",",";","{","}","(",")"};

char ch;

//判断是否为保留字

bool IsKey(string ss) {

int i;

for(i=0;i<8;i++)

if(!strcmp(key[i].c_str(),ss.c_str()))

return true;

return false;

}

//字母判断函数

bool IsLetter(char c) {

if(((c>='a')&&(c<='z'))||((c>='A')&&(c<='Z')))

return true;

return false;

}

//数字判断函数

bool IsDigit(char c) {

if(c>='0'&&c<='9')

return true;

return false;

}

//运算符判断函数

bool IsOptr(string ss) {

int i;

for(i=0;i<4;i++)

if(!strcmp(optr[i].c_str(),ss.c_str()))

return true ;

return false;

}

//分界符判断函数

bool IsSeparator(string ss) {

int i;

for(i=0;i<6;i++)

if(!strcmp(separator[i].c_str(),ss.c_str()))

return true;

return false;

}

void analyse(ifstream &in) {

string st="";

char ch;

int line=1,row=0;

while((in.get(ch))) {

st="";

if((ch==' ')||(ch=='\t')){} //空格，tab健

else

if(ch=='\n') {line++;row=0; } //换行行数加一处理

else

if(IsLetter(ch)) //关键字、标识符的处理

{

row++;

while(IsLetter(ch)||IsDigit(ch))

{

st+=ch;

in.get(ch);

}

in.seekg(-1,ios::cur);//文件指针（光标）后退一个字节

if(IsKey(st)) //判断是否为关键字查询关键字表；

cout<

else //否则为标示符

cout<

}

else

if(IsDigit(ch)) //无符号整数处理

{

row++;

while(IsDigit(ch))

{st+=ch;

ch=in.get();

}

in.seekg(-1,ios::cur);

cout<

// break;

}

else

{st="";

st+=ch;

if(IsOptr(st)) //运算符处理

{

row++;

cout<

}

else

if(IsSeparator(st))//分隔符处理

{ row++;

cout<

}

else{

switch(ch){row++;

case'=' : {row++;cout<<"="<<"\t("<<"="<<","<<"6"<<")"<<'\t'<<"\t关系运算符"<<'\t'<<"("<

case'>' :{row++;ch=in.get();

if(ch=='=')

cout<<">="<<'\t'<<"("<<">="<<","<<"6"<<")"<<'\t'<<"\t关系运算符"<<'\t'<<"("<

else {cout<<">"<<"\t("<<">"<<","<<"6"<<")"<<'\t'<<"\t关系运算符"<<'\t'<<"("<

in.seekg(-1,ios::cur);}

} break;

case'<' :{row++;ch=in.get();

if(ch=='=')cout<<"<="<<'\t'<<"("<<"="<<","<<"6"<<")"<<"\t关系运算符"<<'\t'<<"("<

else if(ch=='>') cout<<"<>"<<'\t'<<"("<<"<>"<<","<<"6"<<")"<<'\t'<<"\t关系运算符"<<'\t'<<"("<

else{cout<<"<"<<"\t("<<"<"<<","<<"6"<<")"<<"\t"<<"\t关系运算符"<<'\t'<<"("<

in.seekg(-1,ios::cur);}

}break;

default :{row++; cout<