编译原理 词法分析器实现程序 C||C++

#include <iostream> #include <fstream> #include <string> #include <string.h> #include <ctype.h> using namespace std; // 保留字数组定义 char* ReserveWords[35] = { "and", "array", "begin", "case", "const", "div", "do", "downto", "else", "end", "file", "for", "function", "goto", "if", "in", "label", "mod", "nil", "not", "of", "or", "packed", "procedure", "program", "record", "repeat", "set", "then", "to", "type", "until", "var", "while", "with" }; char arrow[] = " -----> "; char enter[] = "\r\n"; // 读入ch char GetChar(ifstream& src) { char cRet; src.get(cRet); return cRet; } // 读入空格 char GetBC(ifstream& src) { char cRet; src.get(cRet); while (cRet == ' ') src.get(cRet); return cRet; } // 连接单词符号 void Concat(char *str, char c) { size_t n = strlen(str); str[n++] = c; str[n] = '\0'; } // 判断是否为保留字 bool Reserve(const char* str) { bool bRet = false; for (int i = 0; i < 35; i++) { if (_stricmp(ReserveWords[i], str) == 0) { bRet = true; break; } } return bRet; } // 回调字符 char Retract(ifstream& src) { src.seekg(-1, ios::cur); return '\0'; } // 分析函数 void Analyzer(ifstream& src, ofstream& dst) { char ch; char strToken[1024] = ""; ch = GetBC(src); // 判断标识符的情况 if (isalpha(ch)) { while (isalpha(ch) || isdigit(ch) || ch == '_') { Concat(strToken, ch); ch = GetChar(src); } ch = Retract(src); if (Reserve(strToken)) dst << strToken << arrow << "Reserve Word" << enter; else dst << strToken << arrow << "Identifier" << enter; } // 判断数值的情况 else if (isdigit(ch)) { while (isdigit(ch)) { Concat(strToken, ch); ch = GetChar(src); } Retract(src); dst << strToken << arrow << "Number" << enter; } // 判断字符串的情况 else if (ch == '\'') { Concat(strToken, ch); ch = GetChar(src); while (ch != '\'') { Concat(strToken, ch); ch = GetChar(src); } if (ch != '\'') cerr << "String is too long - more than 1024 bytes!" << endl; else { Concat(strToken, ch); dst << strToken << arrow << "String" << enter; } } // 过滤注释 else if (ch == '{') { while (GetChar(src) != '}') ; } // 判断所有没有歧义的单目运算符 else if (ch == '+') dst << ch << arrow << "Plus" << enter; else if (ch == '-') dst << ch << arrow << "Minus" << enter; else if (ch == '*') dst << ch << arrow << "Multiply" << enter; else if (ch == '/') dst << ch << arrow << "Divide" << enter; else if (ch == '=') dst << ch << arrow << "Equal" << enter; else if (ch == '[') dst << ch << arrow << "Left Square Brackets" << enter; else if (ch == ']') dst << ch << arrow << "Right Square Brackets" << enter; else if (ch == ',') dst << ch << arrow << "Comma" << enter; else if (ch == '^') dst << ch << arrow << "Pointer" << enter; else if (ch == ';') dst << ch << arrow << "Semicolon" << enter; else if (ch == '(') dst << ch << arrow << "Left Parenthesis" << enter; else if (ch == ')') dst << ch << arrow << "Right Parenthesis" << enter; // 判断<、<>和<= else if (ch == '<') { ch = GetChar(src); if (ch == '>') dst << "<>" << arrow << "Unequal" << enter; else if (ch == '=') dst << "<=" << arrow << "Less or Equal" << enter; else { dst << '<' << arrow << "Less" << enter; Retract(src); } } // 判断>和>= else if (ch == '>') { ch = GetChar(src); if (ch == '=') dst << ">=" << arrow << "Greater or Equal" << enter; else { dst << '>' << arrow << "Greater" << enter; Retract(src); } } // 判断.和.. else if (ch == '.') { ch = GetChar(src); if (ch == '.') dst << ".." << arrow << "Bound" << enter; else { dst << '.' << arrow << "Point" << enter; Retract(src); } } // 判断:和:= else if (ch == ':') { ch = GetChar(src); if (ch == '=') dst << ":=" << arrow << "Assign" << enter; else { dst << ':' << arrow << "Colon" << enter; Retract(src); } } } int main(int argc, char* argv[]) { string strSrc; // 命令行的支持 if (argc == 1) { cout << "Please input PASCAL source file name: "; getline(cin, strSrc); } else strSrc = argv[1]; // 打开文件 ifstream src(strSrc.c_str()); if (src.fail()) { cerr << "\aFailed openning \"" << strSrc << "\"!" << endl; return 1; } ofstream dst("Result.txt"); // 开始解析 while (!src.eof()) Analyzer(src, dst); // 收尾工作 dst.close(); src.close(); cout << "The result of Analyzing is written into Result.txt." << endl; return 0; } #include <stdio.h> #include <string.h> #include <ctype.h> #include <alloc.h> #include <conio.h> int IsLetter(char ch) {/*判断是否是字母，是则返回 1，否则返回 0 */ if(isalpha(ch)) return 1; return 0; } int IsDigit(char ch) {/*判断是否为数字，是则返回 1，否则返回 0 */ if(isalnum(ch)) return 1; return