99 line lex analyser

main.c

#include <stdio.h>
#include <string.h>
#include <regex.h>

FILE *in,*out;

int nextChar(char buf[], int* cnt){
	buf[*cnt+1] = '\0';
	return fscanf(in,"%c",&buf[(*cnt)++]) > 0;
}

typedef struct{
	const char *pattern;
	const char* follow[100];
	int toBeOutput;
}TokenPattern;

int compare(const char* pattern, const char* follow, char* s){
	char patternFollow[120];
	regex_t regex;
	switch(follow[0]){
		case '+':case '-':case '*':case '/':case '%':case '=':case '(':case ')':case '{':case '}':case '\n':
			sprintf(patternFollow,"^%s\\%s$",pattern,follow);
			//getchar();
			//printf("%s",patternFollow);
			break;
		default:
			sprintf(patternFollow,"^%s%s$",pattern,follow);
	}
	if (regcomp(&regex, patternFollow, REG_EXTENDED)) {
		printf("Could not compile regex\n");
		return 0;
	}
	if(!regexec(&regex,s,0,NULL,0)){
		printf("Matched (%s) == (%s) with result: %d\n",patternFollow,s,1);
		return 1;	
	}
	return 0;
}

#define SPECIALS " ",";",",","+","-","*","/","%","=","(",")","{","}","<",">"
#define NUMS "0","1","2","3","4","5","6","7","8","9"
#define ALPHAS "q","w","e","r","t","y","u","i","o","p","a","s","d","f","g","h","j","k","l","z","x","c","v","b","n","m"
#define RELOPS "==","!=","<",">","<=",">="

const TokenPattern patterns[] = {
	{"//(.)*\n|/\\*(.)*\\*/",{"","$"},0},
	{"asdl",{"","$"},0},
	{"#include",{"","$"},1},
	{"<(.)+>",{"\n","$"},1},
	{"(if|int|float|char|double|void|for|while|do)",{" ","(","\n","$"},1},
	{"[a-zA-Z_][a-zA-Z_0-9]*",{SPECIALS,RELOPS,"$"},1},
	{"[1-9][0-9]*",{SPECIALS,RELOPS,"$"},1},
	{"(;|,|\\+|\\-|\\*|\\/|\\%|\\=|\\(|\\)|\\{|\\}|==|!=|<|>|<=|>=|\\+\\+|\\-\\-)",{"\n",")",";",ALPHAS,NUMS,"$"},1},
	{"( |\t)",{"","$"},0},
	{"\n",{"","$"},0},
	//{"(.)+",{"\n","$"},0},
	{"$",{}}
};
const char* tokenIds[] = {"mcom","com","include","header","key","id","num","sp","nl","*"};
typedef enum{MCOM, COM, INCLUDE, HEADER, KEY, ID, NUM, SP, NL}PatternType;

int tokenize(char buf[], int *cnt){
	for(unsigned int i=0;patterns[i].pattern[0]!='$';i++) {
		TokenPattern pattern = patterns[i];
		for(unsigned int j=0;pattern.follow[j][0]!='$';j++) {
			char patternBuf[100], followBuf[10];
			strcpy(followBuf, &buf[*cnt - strlen(pattern.follow[j])]);
			strcpy(patternBuf,buf);
			patternBuf[*cnt - strlen(followBuf)] = '\0';
			

			if(compare(pattern.pattern,pattern.follow[j],buf)) {
				if(pattern.toBeOutput)
					fprintf(out,"<%s>%s\t",patternBuf,tokenIds[i]);
				strcpy(buf, followBuf);
				*cnt = strlen(pattern.follow[j]);
				return 1;
			}			
		}
	}
	return 0;
}

int main(){
	in = fopen("in.c","r");
	out = fopen("out.c","w");
	
	char buf[100];int cnt=0;
	while(nextChar(buf,&cnt)){
		printf("(%s,%d)\n",buf,cnt);
		while(tokenize(buf,&cnt));
	}
	printf("---\n");
	fclose(in);
	fclose(out);
	return 0;
}