LexicalAnalysis.cpp

#include <iostream>
#include <fstream>
#include <string>
#include <list>
#include "LexicalAnalysis.h"

using namespace std;


//读取文件
void LexicalAnalysis::readSourceFile(string path) {
 ifstream file;
 file.open(path, ios_base::in);
 if (!file.is_open()) {
 cout << "无法打开文件，请重试！" << endl;
 }

 int i = 0;
 while (getline(file, codeLine[i]))
 {
 i++;
 }
 file.close();
}




//判断字符是否为数字
bool LexicalAnalysis::isDigit(char c) {
 if (c >= '0' && c <= '9')
 return true;
 else
 return false;
}

//判断字符是否为字母
bool LexicalAnalysis::isLetter(char c) {
 if ((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z'))
 return true;
 else
 return false;
}

//判断单词是否为关键字
bool LexicalAnalysis::isKey(string word) {
 int i;
 for (i = 0; i < 11; i++) {
 if (keys[i] == word)
 return true;
 }
 return false;
}

//标识符是否已经存在
bool LexicalAnalysis::idExisted(string name) {
 list<SymbolItem>::iterator plist;
 for (plist = sList.symbolList.begin(); plist != sList.symbolList.end(); plist++) {
 if ((*plist).name == name)
 return true;
 }
 return false;
}

//判断是否为分界符
bool LexicalAnalysis::isSeparated(char c) {
 switch (c) {
 case '(':
 case ')':
 case '{':
 case '}':
 case ';':
 case ',':
 //case '\'':
 return true;
 default:
 return false;
 }
}

//判断是否为单个字符的运算符即+-*/><=!
bool LexicalAnalysis::isOperator(char c) {
 switch (c) {
 case '+':
 case '-':
 case '*':
 case '/':
 case '>':
 case '<':
 case '=':
 case '!':
 case '&':
 case '|':
 return true;
 default:
 return false;
 }
}


//进行词法分析,每次分析一行源代码，填写单词列表和符号表
void LexicalAnalysis::lexAnalysisCodeLine(string code, int line) {
 int i = 0;
 char peek;//字符变量
 Word word;
 string tmp = "";
 bool letterFlag = false;//是否正在识别标识符
 bool digitFlag = false;//是否正在识别数字常量
 bool charFlag = false;//是否正在识别字符常量
 int length = code.length();
 //cout << "长度" << length << endl;
 while (i < length) {
 peek = code[i];
 //前面的代码行已经出现多行注释的前缀
 if (flag) {
 if (peek != '*') {
 i++;
 continue;
 }
 else {
 if (i + 1 < length && code[i + 1] == '/') {
 flag = false;
 i = i + 2;
 cout << "多行注释匹配成功！" << endl;
 continue;
 }
 else {
 i++;
 continue;
 }
 }
 }
 //尚未出现多行注释
 else {
 //直接跳过空格、换行等
 if ((peek == ' ' || peek == '\n') && (!letterFlag) && (!digitFlag) && (!charFlag)) {
 i++;
 cout << "跳过了一次空格" << endl;
 continue;
 }
 //出现单行注释，则可以直接终止分析本行代码
 if (peek == '/' && i + 1 < length && code[i + 1] == '/') {
 cout << "出现单行注释" << endl;
 break;
 //return;
 }
 //出现多行注释
 if (peek == '/' && i + 1 < length && code[i + 1] == '*') {
 flag = true;
 cout << "出现多行注释前缀" << endl;
 i++;
 continue;//可能多行注释的后缀就在本行代码，因此不能退出对本行代码的分析 
 }

 //识别字符常量
 if (!charFlag) {
 if (peek == '\'') {
 charFlag = true;
 i++;
 /*word.type = 5;
 word.value = peek;
 word.line = line;
 word.column = i + 1;
 wList.wordList.push_back(word);*/
 continue;
 }
 }
 else {
 if (isLetter(peek) && i + 1 < length && code[i + 1] == '\'') {
 tmp += peek;
 cout << tmp << endl;
 word.type = 3;
 word.value = tmp;
 word.line = line;
 word.column = i + 1;
 wList.wordList.push_back(word);//写入单词列表
 charFlag = false;
 tmp = ""; 
 i = i + 2;
 continue;
 }
 else {
 //出错处理
 }
 }

 //识别标识符或关键字
 if (!letterFlag) {
 if (isLetter(peek)) {
 letterFlag = true;//开始识别标识符或关键字 
 tmp += peek;
 i++;
 continue;
 }
 }
 else {
 if (isLetter(peek) || isDigit(peek)) {
 tmp += peek;
 i++;
 continue;
 }
 else {

 cout << tmp << endl;
 //单词为关键字
 if (isKey(tmp)) {
 word.type = 4;
 word.value = tmp;
 word.line = line;
 word.column = i;
 wList.wordList.push_back(word);//写入单词列表
 }
 //单词为标识符
 else {

 word.type = 1;
 word.value = tmp;
 word.line = line;
 word.column = i;
 wList.wordList.push_back(word);//写入单词列表
 if (!idExisted(tmp)) {
 SymbolItem sym;
 sym.name = tmp;//标识符名
 sym.line = line;//所属源代码行数 
 sList.symbolList.push_back(sym);//填写符号表
 }
 }
 letterFlag = false;
 tmp = "";//清空以便存储下一个单词内容
 continue;
 }
 }

 //识别数字常量
 if (!digitFlag) {
 if (isDigit(peek)) {
 digitFlag = true;
 tmp += peek;
 i++;
 continue;
 }
 }
 else {
 if (isDigit(peek)) {
 tmp += peek;
 i++;
 continue;
 }
 else {
 cout << tmp << endl;
 word.type = 2;
 word.value = tmp;
 word.line = line;
 word.column = i;
 wList.wordList.push_back(word);//写入单词列表
 digitFlag = false;
 tmp = "";
 continue;
 }
 }


 //运算符
 if (isOperator(peek)) {
 tmp += peek;
 word.type = 6;
 word.line = line;
 switch (peek) {
 case '+':
 if (i + 1 < length && code[i + 1] == '+') {
 tmp += '+';
 word.value = tmp;
 word.column = i + 2;
 i = i + 2;
 wList.wordList.push_back(word);
 }
 else {
 word.value = tmp;
 word.column = i + 1;
 wList.wordList.push_back(word);
 i++;
 }
 break;
 case '-':
 if (i + 1 < length && code[i + 1] == '-') {
 tmp += '-';
 word.value = tmp;
 word.column = i + 2;
 i = i + 2;
 wList.wordList.push_back(word);
 }
 else {
 word.value = tmp;
 word.column = i + 1;
 wList.wordList.push_back(word);
 i++;
 }
 break;
 case '*':
 word.value = tmp;
 word.column = i + 1;
 wList.wordList.push_back(word);
 i++;
 break;
 case '/':
 word.value = tmp;
 word.column = i + 1;
 wList.wordList.push_back(word);
 i++;
 break;
 case '=':
 if (i + 1 < length && code[i + 1] == '=') {
 tmp += '=';
 word.column = i + 2;
 word.value = tmp;
 i = i + 2;
 wList.wordList.push_back(word);
 }
 else {
 word.value = tmp;
 word.column = i + 1;
 wList.wordList.push_back(word);
 i++;
 }
 break;
 case '>':
 if (i + 1 < length && code[i + 1] == '=') {
 tmp += '=';
 word.column = i + 2;
 word.value = tmp;
 i = i + 2;
 wList.wordList.push_back(word);
 }
 else {
 word.value = tmp;
 word.column = i + 1;
 wList.wordList.push_back(word);
 i++;
 }
 break;
 case '<':
 if (i + 1 < length && code[i + 1] == '=') {
 tmp += '=';
 word.column = i + 2;
 word.value = tmp;
 i = i + 2;
 wList.wordList.push_back(word);
 }
 else {
 word.value = tmp;
 word.column = i + 1;
 wList.wordList.push_back(word);
 i++;
 }
 break;
 case '!':
 if (i + 1 < length && code[i + 1] == '=') {
 tmp += '=';
 word.column = i + 2;
 word.value = tmp;
 i = i + 2;
 wList.wordList.push_back(word);
 }
 else {
 word.value = tmp;
 word.column = i + 1;
 wList.wordList.push_back(word);
 i++;
 }
 break;
 case '&':
 if (i + 1 < length && code[i + 1] == '&') {
 tmp += '&';
 word.column = i + 2;
 word.value = tmp;
 i = i + 2;
 wList.wordList.push_back(word);
 }
 else {
 word.value = tmp;
 word.column = i + 1;
 wList.wordList.push_back(word);
 i++;
 }
 break;
 case '|':
 if (i + 1 < length && code[i + 1] == '|') {
 tmp += '|';
 word.column = i + 2;
 word.value = tmp;
 i = i + 2;
 wList.wordList.push_back(word);
 }
 else {
 word.value = tmp;
 word.column = i + 1;
 wList.wordList.push_back(word);
 i++;
 }
 break;
 }
 cout << tmp << endl;
 tmp = "";
 continue;
 }

 //分界符
 if (isSeparated(peek)) {
 tmp += peek;
 word.type = 5;
 word.value = tmp;
 word.line = line;
 word.column = i + 1;
 wList.wordList.push_back(word);
 cout << tmp << endl;
 tmp = "";
 i++;
 continue;
 }


 }

 }
}