/*
	Lexical analyzer.
*/

#include <ctype.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#define __LEXER__
#include "lexer.h"

FILE       *istr;

#define EOFch '\0'
#define TOKLEN 1024
char        linebuf[TOKLEN], *line;
char        token[TOKLEN];
char        lexerror[TOKLEN];
int         len;
int         pos;
int         linenum;

void
lexer_init(FILE * f)
{
	istr = f;
	line = NULL;
	linenum = 0;
	lexer_readToken();
}

static char *
lexer_error(char *s, char *v)
{
	if (v == NULL)
		v = tok;
	sprintf(lexerror, "Line %d:  %s ('%s')\n", linenum, s, v);
	return lexerror;
}

void
lexer_readALine()
{
	int         i;

	if (line = fgets(linebuf, 1024, istr)) {
		pos = 0;
		linenum++;
	}
}

char
lexer_readChar()
{
	if (line == NULL || pos >= strlen(line)) {
		lexer_readALine();
		pos = 0;
	}
	if (line == NULL)
		return EOFch;
	return line[pos++];

}

void
lexer_unreadChar()
{
	pos--;
}

int
lexer_isSpace(char c)
{
	return (c == ' ' || c == '\t');
}

int
lexer_isTokenChar(char c)
{
	return (c == ',' || c == ';' || c == '\n' || c == '\r' || c == '['
			|| c == ']' || c == '#' || c == '=');
}

void
lexer_readAToken()
{
	char        c;
	int         string = 0;

	len = 0;

	do {
		c = lexer_readChar();
	} while (c != EOFch && lexer_isSpace(c));

	if (c != EOFch && c == '\"') {
		string = 1;
		c = lexer_readChar();
	}

	while (c != EOFch && (string ? c != '\"' : !lexer_isSpace(c))) {
		if (!string && lexer_isTokenChar(c)) {
			if (len == 0)
				token[len++] = c;
			else
				lexer_unreadChar();
			token[len] = 0;
			tok = token;
			return;
		} else {
			token[len++] = c;
			c = lexer_readChar();
		}
	}

	if (c == EOFch)
		if (len == 0) {
			token[0] = 0;
			tok = token;
			return;
		} else if (len == 1 && lexer_isTokenChar(token[0])) {
			token[len] = 0;
			tok = token;
			return;
		} else;
	else if (!string)
		lexer_unreadChar();
	tok = token;
	token[len] = 0;
}

void
lexer_readToken()
{
	while (tok == NULL) {
		lexer_readAToken();
	}
}

void
lexer_consumeToken()
{
	if (tok == NULL) {
		lexer_readToken();
		if (tok == NULL)
			logger(LOG_COMMANDS | LOG_FATAL,
				   (lexer_error("Reached premature end-of-file", NULL));
				   } else
				   lexer_readToken();
				   tok = NULL;
				   lexer_readToken();
				   }

				   int lexer_compareToken(char *t) {
				   lexer_readToken();
				   if (strcmp(t, tok) == 0) {
				   lexer_consumeToken(); lexer_readToken(); return 1;}
				   else
				   return 0;}

				   void lexer_matchToken(char *t, char *s) {
				   if (!lexer_compareToken(t))
				   logger(LOG_FATAL | LOG_COMMANDS, (lexer_error(s, tok));}