%{
#include "c.h"
#include "y.tab.h"
extern int lineno;
%}
digit 	[0-9]
num	{digit}+\.?|{digit}*\.{digit}+
letter	[a-zA-Z]
id	{letter}({letter}|{digit})*
%%
[ \t]	{ printf("%s", yytext); }  /* skip blanks and tabs */ 
{num}	{
	sscanf(yytext, "%lf", &yylval.val); 
	yylval.sym = install("", NUMBER, yylval.val);
	printf("%s", yytext);
	return NUMBER; }
{id} 	{
	Symbol *s;
	if ((s=lookup(yytext)) == 0)
		s = install(yytext, UNDEF, 0.0);
	yylval.sym = s;
	printf("%s", yytext);
	return s->type == UNDEF ? ID : s->type; }
"="	{ printf("%s", yytext); return ASSIGN; }
"!="    { printf("%s", yytext); return NE; }
"<"	{ printf("%s", yytext); return follow('=', LE, LT); }
">"	{ printf("%s", yytext); return follow('=', GE, GT); }
"=="	{ printf("%s", yytext); return EQ; }
\n	{ printf("%s", yytext); lineno++; }
.	{ printf("%s", yytext); 
	  return yytext[0]; }  /* everything else */
%%
follow(expect, ifyes, ifno)	/* look ahead for >=, etc. */
{
	int c = getchar();
	if (c == expect) {
		printf("%c", c);
		return ifyes; }
	ungetc(c, stdin);
	return ifno;
}