编译原理词法分析、语法分析和中间代码四元式生成

#include <iostream> #include <sstream> #include <unordered_map> #include <vector> using namespace std; // 定义符号类型枚举 enum SymbolType { VAR, INTEGER, BEGIN, END, IF, THEN, ELSE, WHILE, DO, ASSIGN, PLUS, MINUS, MULTIPLY, DIVIDE, EQUAL, NOTEQUAL, LESS, LESSEQ, GREATER, GREATEREQ, SEMICOLON, LEFTPAREN, RIGHTPAREN, IDENTIFIER, UNSIGNEDINT, SINGLEQUOTE, PERIOD, COMMA }; // 符号结构体 struct Symbol { SymbolType type; // 符号类型 string value; // 符号值 Symbol(SymbolType t, string val) : type(t), value(val) {} }; //四元式结构体 struct Quadruple { string op; // 操作符 string arg1; // 第一个操作数 string arg2; // 第二个操作数 string result; // 结果 string keyword; // 关键字 Quadruple(string op, string arg1, string arg2, string result, string keyword) : op(op), arg1(arg1), arg2(arg2), result(result), keyword(keyword) {} }; unordered_map<string, int> symbolTable; vector<string> intermediateCode; // PASCAL子集的词法分析器 class PascalLexer { private: string input; // 输入字符串 vector<Symbol> symbols; // 识别的符号序列 bool isLetter(char c) { return (c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z'); } bool isDigit(char c) { return c >= '0' && c <= '9'; } void addSymbol(SymbolType type, string value) { symbols.emplace_back(type, value); } public: PascalLexer(string str) : input(str) {} vector<Symbol> getSymbols() { return symbols; } void tokenize() { size_t pos = 0; size_t len = input.length(); while (pos < len) { char ch = input[pos]; if (ch == ' ' || ch == '\t' || ch == '\n') { pos++; continue; // 忽略空格、制表符和换行符 } //判断是否是字母 if (isLetter(ch)) { string identifier; while (pos < len && (isLetter(ch) || isDigit(ch))) { identifier += ch; pos++; ch = input[pos]; } addSymbol(IDENTIFIER, identifier); } //判断是否是数字 else if (isDigit(ch)) { string unsignedInt; while (pos < len && isDigit(ch)) { unsignedInt += ch; pos++; ch = input[pos]; } addSymbol(UNSIGNEDINT, unsignedInt); } else { switch (ch) { case ':': if (pos + 1 < len && input[pos + 1] == '=') { addSymbol(ASSIGN, ":="); pos += 2; } else if (pos + 1 < len && input[pos + 1] == ' ') { addSymbol(INTEGER, ": "); pos += 2; } else { // 错误处理，不符合语法规则 cout << "Error: Unexpected symbol at position " << pos << endl; return; } break; case '\'': addSymbol(SINGLEQUOTE, "'"); pos++; break; case '+': addSymbol(PLUS, "+"); pos++; break; case '-': addSymbol(MINUS, "-"); pos++; break; case '*': addSymbol(MULTIPLY, "*"); pos++; break; case '/': addSymbol(DIVIDE, "/"); pos++; break; case '=': addSymbol(EQUAL, "="); pos++; break; case '<': if (pos + 1 < len && input[pos + 1] == '=') { addSymbol(LESSEQ, "<="); pos += 2; } else { addSymbol(LESS, "<"); pos++; } break; case '>': if (pos + 1 < len && input[pos + 1] == '=') { addSymbol(GREATEREQ, ">="); pos += 2; } else { addSymbol(GREATER, ">"); pos++; } break; case ';': addSymbol(SEMICOLON, ";"); pos++; break; case '(': addSymbol(LEFTPAREN, "("); pos++; break; case ')': addSymbol(RIGHTPAREN, ")"); pos++; break; case ',': addSymbol(COMMA, ","); pos++; break; case '.': addSymbol(PERIOD, "."); pos++; break; default: // 错误处理，不符合语法规则 cout << "Error: Unexpected symbol at position " << pos << endl; return; } } } } }; //语法分析 class SyntaxAnalyzer { private: //表示当前解析的位置 int position = 0; vector<Symbol> symbols; //标志当前进行递归语法检查的次数 int has = 0; //判断是否是字母 bool isAlphaString(const string& str) { for (char c : str) { if (!isalpha(c)) { return false; // 字符串中含有非字母字符，返回false } } return true; // 字符串中所有字符都是字母，返回true } //判断是否是数字 bool isDigitString(const string& str) { for (char c : str) { if (!isdigit(c)) { return false; // 字符串中含有非字母字符，返回false } } return true; // 字符串中所有字符都是字母，返回true } //判断是否是关键字 bool isKeyword(string str) { if (str == "var" || str == "begin" || str == "if" || str == "then" || str == "else" || str == "while" || str == "do" || str == "end") return true; else return false; } //判断是否是算术符号 bool isSymbol(const string& str) { for (char c : str) { if (c == '+' || c == '-' || c == '*' || c == '/' || c == '(' || c == ')') return true; else break; } return false; } //判断是否是不等式 bool isnext(const string& str) { for (char c : str) { if (c == '>' || c == '<') return true; else break; } return false; } //移动位置position int move(int p) { p = p - 2; return p; } //判断是否结束 bool isEnd(const string& str) { for (char c : str) { if (c == ';' || c == '.') return true; else break; } return false; } public: SyntaxAnalyzer(vector<Symbol> strs){ symbols = strs; } //表达式分析 void term() { if (position