/**
 * @file     lexan.c
 * @provides lexan
 *
 * $Id: lexan.c 166 2007-07-11 01:03:18Z brylow $
 */
/* Embedded XINU, Copyright (C) 2007.  All rights reserved. */

#include <kernel.h>
#include <shell.h>

/**
 * Ad hoc lexical analyzer to divide command line into tokens
 * @param *line   pointer to line to parse
 * @param linelen length of line to parse
 * @param *tokbuf buffer for tokens 
 * @param *tok[]  array of pointers into token buffer
 * @return number of tokens created
 */
short lexan(char *line, ushort linelen, char *tokbuf, char *tok[])
{
	char   quote;                  /* character for quoted string  */
	ushort ntok = 0;               /* number of tokens parsed      */
	ushort i = 0;                  /* temp variable                */

	while ((i < linelen) && (ntok < SHELL_MAXTOK))
	{
		/* Skip whitespace in line of input */
		while (isWhitespace(line[i]) && (i < linelen))
		{ i++; }

		/* Stop parsing at end of line */
		if (isEndOfLine(line[i]) || (i >= linelen))
		{ return ntok; }

		/* Set token to point to value in token buffer */
		tok[ntok] = tokbuf;

		/* Handle quoted string */
		if (isQuote(line[i]))
		{
			quote = *tokbuf++ = line[i++];

			while ( (quote != line[i])
			     && (!isEndOfLine(line[i])) && (i < linelen))
			{ *tokbuf++ = line[i++]; }

			if (quote == line[i])
			{ *tokbuf++ = line[i++]; }
			else
			{ return SYSERR; }
		}
		else
		{
			*tokbuf++ = line[i++];

			/* Handle standard alphanumeric token */
			if (!isOtherSpecial(line[i-1]))
			{
				while ( (!isEndOfLine(line[i])) && (!isQuote(line[i]))
				     && (!isOtherSpecial(line[i])) && (!isWhitespace(line[i]))
				     && (i < linelen) )
				{ *tokbuf++ = line[i++]; }

				if (i >= linelen)
					return SYSERR;
			}
		}

		/* Finish current token */
		*tokbuf++ = '\0';
		ntok++; 
	}

	return ntok;
}