cifa.zip_5M7_编译原理实验

#define _CRT_SECURE_NO_WARNINGS #include<iostream> #include<cstring> #include<stdio.h> #include<string> using namespace std; char character; char token[20] = { 0 }; char buff[2000]; int nowLoc=-1; char symbol_table[100][20] = { 0 }; char constant_table[100][20] = { 0 }; char reserved_words[15][20] = { "", "begin", "end", "integer", "if", "then", "else", "function", "read", "write" }; char get_char() { nowLoc++; character = buff[nowLoc]; return character; } void getnbc() { if (character == ' ') get_char(); } void concat() { int i = 0; while (token[i] != '\0') { i++; } token[i] = character; token[i + 1] = '\0'; } bool letter() { if (character>= 'a'&&character <= 'z' || character >= 'A'&&character <= 'Z') return true; else return false; } bool digit() { if (character >= '0'&&character <= '9') return true; else return false; } // token 最后一个字母 void retract() { nowLoc--; character = ' '; } int reserve() { for (int i = 1; i < 11; i++) { if (strcmp(token, reserved_words[i]) == 0) return i; } return 0; } int symbol() { int i = 0; while (strcmp(symbol_table[i], "") != 0) { if (strcmp(symbol_table[i], token) == 0) return i; else i++; } strcpy_s(symbol_table[i], token); return i; } void return_tuple(char* s,int x) { for (int i = 0; i < 16 - strlen(s); i++) cout << " "; cout << s << " "; if (x < 10) cout << " " << x << endl; else cout << x << endl; } void error() { } void Lex() { char str_num[20] = { 0 }; memset(token, 0, 20); /*get_char();*/ getnbc(); int num, val; //num保留字位置， val变量表位置 switch (character) { case 'a':case 'b':case 'c':case 'd':case 'e':case 'f':case 'g':case 'h':case 'i': case 'j':case 'k':case 'l':case 'm':case 'n':case 'o':case 'p':case 'q':case 'r': case 's':case 't':case 'u':case 'v':case 'w':case 'x':case 'y':case 'z': case 'A':case 'B':case 'C':case 'D':case 'E':case 'F':case 'G':case 'H':case 'I': case 'J':case 'K':case 'L':case 'M':case 'N':case 'O':case 'P':case 'Q':case 'R': case 'S':case 'T':case 'U':case 'V':case 'W':case 'X':case 'Y':case 'Z': while (letter() || digit()) { concat(); get_char(); } retract(); num = reserve(); if (num != 0) return_tuple(reserved_words[num], num); else { val = symbol(); return_tuple(symbol_table[val], val); } break; case '0':case '1':case '2':case '3':case '4':case '5':case '6':case '7':case '8':case '9': while (digit()) { concat(); get_char(); } strcmp(str_num, token); retract(); return_tuple(str_num, 11); break; case '<': get_char(); if (character == '=') return_tuple("<=", 14); else if (character == '>') return_tuple("<>", 13); else { retract(); return_tuple("<", 15); } break; case '>': get_char(); if (character == '=') return_tuple(">=", 16); else { retract(); return_tuple(">", 17); } break; case ':': get_char(); if (character == '=') return_tuple(":=", 20); else { retract(); //出错处理 } break; case '-': return_tuple("-", 18); break; case '*': return_tuple("*", 19); break; case '(': return_tuple("(", 21); break; case ')': return_tuple(")", 22); break; case ';': return_tuple(";", 23); break; default: error(); // } } int main() { cout << "代码："<<endl; char c; string buff_ex; FILE *fp; char* file_name = "D:\\develop\\cifa\\nplus.pas"; puts(file_name); fp = fopen(file_name, "r"); //打开文件 char ch; int i = 0; while ((ch = fgetc(fp)) != EOF) { buff[i] = ch; i++; putchar(ch); } //输出一个字符 fclose(fp); //关闭文件指针 /*puts(buff);*/ while (get_char() != '\0') { Lex(); } system("pause"); return 0; }