%{
#include <stdlib.h>
/*
#define token(x) x
*/
#define EndTable(v) (v-1 + sizeof v/sizeof v[0])
int screen();
int addword(int type, char *word);
int lookup_word(char *word);
#define constant 1
#define identifier 2
#define NOTFOUND -1
%}
%%
":="	{ printf("%s: ASSIGN", yytext);  return(7);}
":"	{ printf("%s: COLON", yytext);  return(8);}
","	{ printf("%s: COMMA", yytext);  return(9);}
"."	{ printf("%s: DOT", yytext);  return(10);}
"="	{ printf("%s: EQUAL", yytext);  return(11);}
"*"	{ printf("%s: MULT", yytext);  return(12);}
"+"	{ printf("%s: PLUS", yytext);  return(13);}
";"	{ printf("%s: SEMICOL", yytext);  return(14);}
[\t\n]+	{  printf("%s: WhiteSpace", yytext); }
[ ]+	{  printf("%s: WhiteSpace", yytext); }
[0-9][0-9]*	{printf("%s: const", yytext); addword(constant, yytext); return(15);}
[a-zA-Z_][a-zA-Z0-9]*	{ return screen();}
%%
main(){
	char *p;

        while(p= (char *)yylex())
		;
	printf("\nsuccessful scanning.\n");
}

static struct rwtable{
	char *rw_name;
	int rw_yylex;
} rwtable[] = {
	"BEGIN",	1,
	"CONST",	2,
	"END",		3,
        "INTEGER",      4,
	"PROGRAM",	5,
	"VAR",		6,
};

struct word{
	char *word_name;
	int word_type;
/*	int value; */
	struct word *next;
};

struct word *word_list = NULL;


int addword(int type, char *word)
{
	struct word *wp;

	wp = (struct word *) malloc(sizeof(struct word));
	wp->next = word_list;
	wp->word_name = (char *) malloc(strlen(word)+1);
	strcpy(wp->word_name, word);
	wp->word_type = type;
/*	wp->value = ; */
	word_list = wp;
	return 1;
}

int lookup_word(char *word)
{
	struct word *wp = word_list;

	for(;wp;wp = wp->next){
		if(strcmp(wp->word_name, word) == 0)
			return(wp->word_type);
	}
	return NOTFOUND;
}

int screen()
{
	struct rwtable *low = rwtable,
			*high = EndTable(rwtable),
			*mid;
	int c;

	while(low <= high){
		mid = low + (high - low)/2;
		if((c = strcmp(mid->rw_name, yytext)) == 0){
			printf("%s: keyword", yytext);
			return(mid->rw_yylex);
		}
		else{
			if(c < 0) 
				low = mid + 1;
			else
				high = mid - 1;
		}
	}
	if(lookup_word(yytext) != NOTFOUND){
		printf("%s: id", yytext);
		return(16);
	}
	else{
		addword(identifier, yytext);
		printf("%s: id", yytext);
		return(16);
	}	
}