yufa.zip_C语言_编译原理作业_编译语法分析_语法分析_语法分析器

#include<iostream> #include<cstdio> #include<cstring> #include<cmath> using namespace std; #define MAXN 20000 int syn, p, sum, kk, m, n, row, error; double dsum, pos; char index[800], len; char r[6][10] = {"function", "if", "then", "while", "do", "endfunc"}; char token[MAXN], s[MAXN]; char ch; bool is_letter(char c) { return c >= 'a' && c <= 'z' || c >= 'A' && c <= 'Z'; } bool is_digtial(char c) { return c >= '0' && c <= '9'; } bool is_dot(char c) { return c == ',' || c == ';'; } void identifier()// 标示符的判断 { m = 0; while (ch >= 'a' && ch <= 'z' || ch >= '0' && ch <= '9') { token[m++] = ch; ch = s[++p]; } token[m] = '\0'; ch = s[--p]; syn = 10; for (n = 0; n < 6; n++) if (strcmp(token, r[n]) == 0) { syn = n+1; break; } } void digit(bool positive)// 数字的判断 { len = sum = 0; ch = s[p]; while (ch >= '0' && ch <= '9') { sum = sum * 10 + ch - '0'; ch = s[++p]; } if (ch == '.') { dsum = sum; syn = 12; ch = s[++p]; pos = 0.1; while (ch >= '0' && ch <= '9') { dsum = dsum + (ch - '0') * pos; pos = pos * 0.1; ch = s[++p]; } if (ch == 'e') { index[len++] = ch; ch = s[++p]; if (ch == '-' || ch == '+') { index[len++] = ch; ch = s[++p]; } if (!(ch >= '0' && ch <= '9')) { //cout<<"Looooooooooook"<<endl; syn = -1; } else { while (ch >= '0' && ch <= '9') { index[len++] = ch; ch = s[++p]; } } } if (syn == -1 || (ch >= 'a' && ch <= 'z') || ch == '.') { syn = -1; // 对数字开头的标识符进行判错。 while (ch >= '0' && ch <= '9' || ch >= 'a' && ch <= 'z' || ch == '.') ch = s[++p]; ch = s[--p]; } else { ch = s[--p]; syn = 12; if (!positive) dsum *= -1.0; } } else { if (ch >= 'a' && ch <= 'z') { syn = -1; // 对数字开头的标识符进行判错。 while (ch >= '0' && ch <= '9' || ch >= 'a' && ch <= 'z') ch = s[++p]; ch = s[--p]; } else { ch = s[--p]; syn = 11; if (!positive) sum *= -1; } } } void To_double() { int i; printf("(%d,%lf", syn, dsum); if (len) { for (i = 0; i < len; i++) printf("%c", index[i]); len = 0; } printf(")\n"); } bool check_behind_digit() { int i = p + 1; while (s[i] != '\0') { if (s[i] >= '0' && s[i] <= '9') return true; else if (s[i] != ' ' && s[i] != '\t' && s[i] != '\n') return false; i++; } return false; } bool check_pre_prog() { int i = p - 1; while (i >= 0) { if (s[i] != ' ' && s[i] != '\t' && s[i] != '\n') { if (s[i] >= '0' && s[i] <= '9' || s[i] >= 'a' && s[i] <= 'z') return false; else return true; } i--; } return true; } void pot() { while (1) { ch = s[++p]; if (ch == '\n') row++; if (!(ch == ' ' || ch == '\t' || ch == '\n')) break; } } void scaner() { memset(token, 0, sizeof(token)); pot(); if (is_letter(ch)) { syn = 10; identifier(); } else if (is_digtial(ch)) { digit(true); } else { if (ch == '<') { len = 0, token[len++] = ch; if (s[p + 1] == '=') { syn = 22; token[len++] = s[p + 1]; p++; } else syn = 20; token[len] = 0; } else if (ch == '>') { len = 0, token[len++] = ch; if (s[p + 1] == '=') { syn = 24; token[len++] = s[p + 1]; p++; } else syn = 23; token[len] = 0; } else if (ch == '=') { len = 0, token[len++] = ch; if (s[p + 1] == '=') { syn = 25; token[len++] = s[p + 1]; p++; } else syn = 18; token[len] = 0; } else if (ch == '!') { len = 0, token[len++] = ch; if (s[p + 1] == '=') { syn = 22; token[len++] = s[p + 1]; p++; } else syn = -1; } else if (ch == '+') { if (check_behind_digit() && check_pre_prog()) { pot(); digit(true); } else { syn = 13; token[0] = ch; } } else if (ch == '-') { if (check_behind_digit() && check_pre_prog()) { pot(); digit(false); } else { syn = 13; token[0] = ch; } } else if (ch == '*') syn = 15, strcpy(token, "*"); else if (ch == '/') syn = 16, strcpy(token, "/"); else if (ch == ';') syn = 26, strcpy(token, ";"); else if (ch == '(') syn = 27, strcpy(token, "("); else if (ch == ')') syn = 2