symbol.cpp

一个简单的实现加减乘除的编译器

#include"global.h"
#include"error.h"
#define STRMAX 999
#define SYMMAX 100

char lexemes[STRMAX];
int lastchar=-1;
struct entry symtable[SYMMAX];
int lastentry=0;

int lookup(char s[]){
	int p;
	for(p=lastentry;p>0;p=p-1)
		if(strcmp(symtable[p].lexptr,s)==0)
			return p;
		return 0;
}
int insert(char s[],int tok){
	int len;
	len=strlen(s);
    if(lastentry+1>=SYMMAX)
		error("symbol table full");
	if(lastchar+len+1>=STRMAX)
		error("lexemes array full");
	lastentry=lastentry+1;
	symtable[lastentry].token=tok;
	symtable[lastentry].lexptr=&lexemes[lastchar+1];
	lastchar=lastchar+len+1;
	strcpy(symtable[lastentry].lexptr,s);
	return lastentry;
}