用java实现的词法分析器

#include <stdio.h> #include <string.h> #include <malloc.h> #include <header.h> typedef struct { char *base; int stacksize; int top; }MySignStack; typedef struct { int *base; int stacksize; int top; }MyDataStack; status InitSignStack(MySignStack &S); status InitDataStack(MyDataStack &S); status PushSign(MySignStack &S,char e); status PushData(MyDataStack &S,int e); status PopSign(MySignStack &S,char &e); status PopData(MyDataStack &S,int &e); char GetTopSign(MySignStack &S); int GetTopData(MyDataStack &S); char Compare(char a,char b); status IsData(char c); int Operation(int a,int b,char c); void main() { MySignStack SignStack; MyDataStack DataStack; InitSignStack(SignStack); InitDataStack(DataStack); PushSign(SignStack,'#'); /*printf("请按照正确的顺序输入表达式，以‘#’结束：\n"); char c=getchar();*/ char c=getchar(); char temp; int a,b; int number=0; int flag=0; while(c!= '#' || GetTopSign(SignStack)!='#') { number=0; flag=0; while(IsData(c)) { number =number*10+ (c-'0'); c=getchar(); flag=1; } if(flag==1) PushData(DataStack,number); switch(Compare(GetTopSign(SignStack),c)) { case '<': PushSign(SignStack,c); c=getchar(); break; case '=': PopSign(SignStack,temp); c=getchar(); break; case '>': PopSign(SignStack,temp); PopData(DataStack,a); PopData(DataStack,b); PushData(DataStack,Operation(a,b,temp)); break; default: break; } } printf("%d",GetTopData(DataStack)); } status InitSignStack(MySignStack &S) { S.base=(char *)malloc(sizeof(char)*INITSIZE); if(!S.base) return ERROR; S.top=0; S.stacksize=INITSIZE; return OK; } status InitDataStack(MyDataStack &S) { S.base=(int *)malloc(sizeof(int)*INITSIZE); if(!S.base) return ERROR; S.top=0; S.stacksize=INITSIZE; return OK; } status PushSign(MySignStack &S,char e) { if(S.top==S.stacksize) { S.base=(char *)realloc(S.base,S.stacksize+INCREMENT); S.stacksize+=INCREMENT; } S.base[S.top++]=e; //printf("the sign is %c\n",S.base[S.top-1]); return OK; } status PushData(MyDataStack &S,int e) { if(S.top==S.stacksize) { S.base=(int *)realloc(S.base,S.stacksize+INCREMENT); S.stacksize+=INCREMENT; } S.base[S.top++]=e; //printf("the data is %d\n",S.base[S.top-1]); return OK; } status PopSign(MySignStack &S,char &e) { if(S.top==0) return ERROR; e=S.base[--S.top]; return OK; } status PopData(MyDataStack &S,int &e) { if(S.top==0) return ERROR; e=S.base[--S.top]; return OK; } char GetTopSign(MySignStack &S) { char e; if(S.top==0) return ERROR; e=S.base[S.top-1]; return e; } int GetTopData(MyDataStack &S) { int e; if(S.top==0) return ERROR; e=S.base[S.top-1]; return e; } char Compare(char a,char b) { if(a=='+') { if(b=='+' || b=='-' || b==')' || b=='#') return '>'; else return '<'; } if(a=='-') { if(b=='*' || b=='/' || b=='(') return '<'; else return '>'; } if(a=='*') { if(b=='(') return '<'; else return '>'; } if(a=='/') { if(b=='(') return '<'; else return '>'; } if(a=='(') { if(b==')') return '='; else return '<'; } if(a==')') { return '>'; } if(a=='#') { if(b=='#') return '='; else return '<'; } } status IsData(char c) { if(c>='0' && c<='9') return 1; else return 0; } int Operation(int a,int b,char c) { if(c=='+') return b+a; if(c=='-') return b-a; if(c=='*') return a*b; if(c=='/') return b/a; }