/*
 * Copyright 1994 Christopher Seiwald.  All rights reserved. 
 *
 * This file is part of Jam - see jam.c for Copyright information.
 */

/*
 * glob.c - match a string against a simple pattern
 *
 * Understands the following patterns:
 *
 *	*	any number of characters
 *	?	any single character
 *	[a-z]	any single character in the range a-z
 *	[^a-z]	any single character not in the range a-z
 *	\x	match x
 *	
 * External functions:
 *
 *	glob() - match a string against a simple pattern
 *
 * Internal functions:
 *
 *	globchars() - build a bitlist to check for character group match
 */

# include "jam.h"

# define CHECK_BIT( tab, bit ) ( tab[ (bit)/8 ] & (1<<( (bit)%8 )) )
# define BITLISTSIZE 16	/* bytes used for [chars] in compiled expr */

static void globchars( char *s, char *e, char *b );

/*
 * glob() - match a string against a simple pattern
 */

int
glob(
	register char *c,
	register char *s )
{
	char bitlist[ BITLISTSIZE ];
	char *here;

	for( ;; )
	    switch( *c++ )
	{
	case '\0':
		return *s ? -1 : 0;

	case '?':
		if( !*s++ )
		    return 1;
		break;

	case '[':
		/* scan for matching ] */

		here = c;
		do if( !*c++ )
			return 1;
		while( here == c || *c != ']' );
		c++;

		/* build character class bitlist */

		globchars( here, c, bitlist );

		if( !CHECK_BIT( bitlist, *(unsigned char *)s ) )
			return 1;
		s++;
		break;

	case '*':
		here = s;

		while( *s ) 
			s++;

		/* Try to match the rest of the pattern in a recursive */
		/* call.  If the match fails we'll back up chars, retrying. */

		while( s != here )
		{
			int r;

			/* A fast path for the last token in a pattern */

			r = *c ? glob( c, s ) : *s ? -1 : 0;

			if( !r )
				return 0;
			else if( r < 0 )
				return 1;

			--s;
		}
		break;

	case '\\':
		/* Force literal match of next char. */

		if( !*c || *s++ != *c++ )
		    return 1;
		break;

	default:
		if( *s++ != c[-1] )
		    return 1;
		break;
	}
}

/*
 * globchars() - build a bitlist to check for character group match
 */

static void
globchars( 
	char *s, 
	char *e, 
	char *b )
{
	int neg = 0;

	memset( b, '\0', BITLISTSIZE  );

	if( *s == '^') 
		neg++, s++;

	while( s < e )
	{
		int c;

		if( s+2 < e && s[1] == '-' )
		{
			for( c = s[0]; c <= s[2]; c++ )
				b[ c/8 ] |= (1<<(c%8));
			s += 3;
		} else {
			c = *s++;
			b[ c/8 ] |= (1<<(c%8));
		}
	}
			
	if( neg )
	{
		int i;
		for( i = 0; i < BITLISTSIZE; i++ )
			b[ i ] ^= 0377;
	}

	/* Don't include \0 in either $[chars] or $[^chars] */

	b[0] &= 0376;
}
