/* 

 * tclParse.c --

 *

 *	This file contains procedures that parse Tcl scripts.  They

 *	do so in a general-purpose fashion that can be used for many

 *	different purposes, including compilation, direct execution,

 *	code analysis, etc.  

 *

 * Copyright (c) 1997 Sun Microsystems, Inc.

 * Copyright (c) 1998-2000 Ajuba Solutions.

 * Portions Copyright (c) 2007-2008 Nokia Corporation and/or its subsidiaries. All rights reserved.  

 * Contributions from Don Porter, NIST, 2002. (not subject to US copyright)

 *

 * See the file "license.terms" for information on usage and redistribution

 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.

 *

 * RCS: @(#) $Id: tclParse.c,v 1.25.2.1 2006/09/24 21:15:10 msofer Exp $

 */

#include "tclInt.h"

#include "tclPort.h"

/*

 * The following table provides parsing information about each possible

 * 8-bit character.  The table is designed to be referenced with either

 * signed or unsigned characters, so it has 384 entries.  The first 128

 * entries correspond to negative character values, the next 256 correspond

 * to positive character values.  The last 128 entries are identical to the

 * first 128.  The table is always indexed with a 128-byte offset (the 128th

 * entry corresponds to a character value of 0).

 *

 * The macro CHAR_TYPE is used to index into the table and return

 * information about its character argument.  The following return

 * values are defined.

 *

 * TYPE_NORMAL -        All characters that don't have special significance

 *                      to the Tcl parser.

 * TYPE_SPACE -         The character is a whitespace character other

 *                      than newline.

 * TYPE_COMMAND_END -   Character is newline or semicolon.

 * TYPE_SUBS -          Character begins a substitution or has other

 *                      special meaning in ParseTokens: backslash, dollar

 *                      sign, or open bracket.

 * TYPE_QUOTE -         Character is a double quote.

 * TYPE_CLOSE_PAREN -   Character is a right parenthesis.

 * TYPE_CLOSE_BRACK -   Character is a right square bracket.

 * TYPE_BRACE -         Character is a curly brace (either left or right).

 */

#define TYPE_NORMAL             0

#define TYPE_SPACE              0x1

#define TYPE_COMMAND_END        0x2

#define TYPE_SUBS               0x4

#define TYPE_QUOTE              0x8

#define TYPE_CLOSE_PAREN        0x10

#define TYPE_CLOSE_BRACK        0x20

#define TYPE_BRACE              0x40

#define CHAR_TYPE(c) (charTypeTable+128)[(int)(c)]

static CONST char charTypeTable[] = {

    /*

     * Negative character values, from -128 to -1:

     */

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    /*

     * Positive character values, from 0-127:

     */

    TYPE_SUBS,        TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_SPACE,       TYPE_COMMAND_END, TYPE_SPACE,

    TYPE_SPACE,       TYPE_SPACE,       TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_SPACE,       TYPE_NORMAL,      TYPE_QUOTE,       TYPE_NORMAL,

    TYPE_SUBS,        TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_CLOSE_PAREN, TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_COMMAND_END,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_SUBS,

    TYPE_SUBS,        TYPE_CLOSE_BRACK, TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_BRACE,

    TYPE_NORMAL,      TYPE_BRACE,       TYPE_NORMAL,      TYPE_NORMAL,

    /*

     * Large unsigned character values, from 128-255:

     */

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

    TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,      TYPE_NORMAL,

};

/*

 * Prototypes for local procedures defined in this file:

 */

static int		CommandComplete _ANSI_ARGS_((CONST char *script,

			    int numBytes));

static int		ParseComment _ANSI_ARGS_((CONST char *src, int numBytes,

			    Tcl_Parse *parsePtr));

static int		ParseTokens _ANSI_ARGS_((CONST char *src, int numBytes,

			    int mask, Tcl_Parse *parsePtr));

/*

 *----------------------------------------------------------------------

 *

 * Tcl_ParseCommand --

 *

 *	Given a string, this procedure parses the first Tcl command

 *	in the string and returns information about the structure of

 *	the command.

 *

 * Results:

 *	The return value is TCL_OK if the command was parsed

 *	successfully and TCL_ERROR otherwise.  If an error occurs

 *	and interp isn't NULL then an error message is left in

 *	its result.  On a successful return, parsePtr is filled in

 *	with information about the command that was parsed.

 *

 * Side effects:

 *	If there is insufficient space in parsePtr to hold all the

 *	information about the command, then additional space is

 *	malloc-ed.  If the procedure returns TCL_OK then the caller must

 *	eventually invoke Tcl_FreeParse to release any additional space

 *	that was allocated.

 *

 *----------------------------------------------------------------------

 */

EXPORT_C int

Tcl_ParseCommand(interp, string, numBytes, nested, parsePtr)

    Tcl_Interp *interp;		/* Interpreter to use for error reporting;

				 * if NULL, then no error message is

				 * provided. */

    CONST char *string;		/* First character of string containing

				 * one or more Tcl commands. */

    register int numBytes;	/* Total number of bytes in string.  If < 0,

				 * the script consists of all bytes up to 

				 * the first null character. */

    int nested;			/* Non-zero means this is a nested command:

				 * close bracket should be considered

				 * a command terminator. If zero, then close

				 * bracket has no special meaning. */

    register Tcl_Parse *parsePtr;

    				/* Structure to fill in with information

				 * about the parsed command; any previous

				 * information in the structure is

				 * ignored. */

{

    register CONST char *src;	/* Points to current character

				 * in the command. */

    char type;			/* Result returned by CHAR_TYPE(*src). */

    Tcl_Token *tokenPtr;	/* Pointer to token being filled in. */

    int wordIndex;		/* Index of word token for current word. */

    int terminators;		/* CHAR_TYPE bits that indicate the end

				 * of a command. */

    CONST char *termPtr;	/* Set by Tcl_ParseBraces/QuotedString to

				 * point to char after terminating one. */

    int scanned;

    if ((string == NULL) && (numBytes!=0)) {

	if (interp != NULL) {

	    Tcl_SetResult(interp, "can't parse a NULL pointer", TCL_STATIC);

	}

	return TCL_ERROR;

    }

    if (numBytes < 0) {

	numBytes = strlen(string);

    }

    parsePtr->commentStart = NULL;

    parsePtr->commentSize = 0;

    parsePtr->commandStart = NULL;

    parsePtr->commandSize = 0;

    parsePtr->numWords = 0;

    parsePtr->tokenPtr = parsePtr->staticTokens;

    parsePtr->numTokens = 0;

    parsePtr->tokensAvailable = NUM_STATIC_TOKENS;

    parsePtr->string = string;

    parsePtr->end = string + numBytes;

    parsePtr->term = parsePtr->end;

    parsePtr->interp = interp;

    parsePtr->incomplete = 0;

    parsePtr->errorType = TCL_PARSE_SUCCESS;

    if (nested != 0) {

	terminators = TYPE_COMMAND_END | TYPE_CLOSE_BRACK;

    } else {

	terminators = TYPE_COMMAND_END;

    }

    /*

     * Parse any leading space and comments before the first word of the

     * command.

     */

    scanned = ParseComment(string, numBytes, parsePtr);

    src = (string + scanned); numBytes -= scanned;

    if (numBytes == 0) {

	if (nested) {

	    parsePtr->incomplete = nested;

	}

    }

    /*

     * The following loop parses the words of the command, one word

     * in each iteration through the loop.

     */

    parsePtr->commandStart = src;

    while (1) {

	/*

	 * Create the token for the word.

	 */

	if (parsePtr->numTokens == parsePtr->tokensAvailable) {

	    TclExpandTokenArray(parsePtr);

	}

	wordIndex = parsePtr->numTokens;

	tokenPtr = &parsePtr->tokenPtr[wordIndex];

	tokenPtr->type = TCL_TOKEN_WORD;

	/*

	 * Skip white space before the word. Also skip a backslash-newline

	 * sequence: it should be treated just like white space.

	 */

	scanned = TclParseWhiteSpace(src, numBytes, parsePtr, &type);

	src += scanned; numBytes -= scanned;

	if (numBytes == 0) {

	    parsePtr->term = src;

	    break;

	}

	if ((type & terminators) != 0) {

	    parsePtr->term = src;

	    src++;

	    break;

	}

	tokenPtr->start = src;

	parsePtr->numTokens++;

	parsePtr->numWords++;

	/*

	 * At this point the word can have one of three forms: something

	 * enclosed in quotes, something enclosed in braces, or an

	 * unquoted word (anything else).

	 */

	if (*src == '"') {

	    if (Tcl_ParseQuotedString(interp, src, numBytes,

		    parsePtr, 1, &termPtr) != TCL_OK) {

		goto error;

	    }

	    src = termPtr; numBytes = parsePtr->end - src;

	} else if (*src == '{') {

	    if (Tcl_ParseBraces(interp, src, numBytes,

		    parsePtr, 1, &termPtr) != TCL_OK) {

		goto error;

	    }

	    src = termPtr; numBytes = parsePtr->end - src;

	} else {

	    /*

	     * This is an unquoted word.  Call ParseTokens and let it do

	     * all of the work.

	     */

	    if (ParseTokens(src, numBytes, TYPE_SPACE|terminators,

		    parsePtr) != TCL_OK) {

		goto error;

	    }

	    src = parsePtr->term; numBytes = parsePtr->end - src;

	}

	/*

	 * Finish filling in the token for the word and check for the

	 * special case of a word consisting of a single range of

	 * literal text.

	 */

	tokenPtr = &parsePtr->tokenPtr[wordIndex];

	tokenPtr->size = src - tokenPtr->start;

	tokenPtr->numComponents = parsePtr->numTokens - (wordIndex + 1);

	if ((tokenPtr->numComponents == 1)

		&& (tokenPtr[1].type == TCL_TOKEN_TEXT)) {

	    tokenPtr->type = TCL_TOKEN_SIMPLE_WORD;

	}

	/*

	 * Do two additional checks: (a) make sure we're really at the

	 * end of a word (there might have been garbage left after a

	 * quoted or braced word), and (b) check for the end of the

	 * command.

	 */

	scanned = TclParseWhiteSpace(src, numBytes, parsePtr, &type);

	if (scanned) {

	    src += scanned; numBytes -= scanned;

	    continue;

	}

	if (numBytes == 0) {

	    parsePtr->term = src;

	    break;

	}

	if ((type & terminators) != 0) {

	    parsePtr->term = src;

	    src++; 

	    break;

	}

	if (src[-1] == '"') { 

	    if (interp != NULL) {

		Tcl_SetResult(interp, "extra characters after close-quote",

			TCL_STATIC);

	    }

	    parsePtr->errorType = TCL_PARSE_QUOTE_EXTRA;

	} else {

	    if (interp != NULL) {

		Tcl_SetResult(interp, "extra characters after close-brace",

			TCL_STATIC);

	    }

	    parsePtr->errorType = TCL_PARSE_BRACE_EXTRA;

	}

	parsePtr->term = src;

	goto error;

    }

    parsePtr->commandSize = src - parsePtr->commandStart;

    return TCL_OK;

    error:

    Tcl_FreeParse(parsePtr);

    if (parsePtr->commandStart == NULL) {

	parsePtr->commandStart = string;

    }

    parsePtr->commandSize = parsePtr->end - parsePtr->commandStart;

    return TCL_ERROR;

}

/*

 *----------------------------------------------------------------------

 *

 * TclParseWhiteSpace --

 *

 *	Scans up to numBytes bytes starting at src, consuming white

 *	space as defined by Tcl's parsing rules.  

 *

 * Results:

 *	Returns the number of bytes recognized as white space.  Records

 *	at parsePtr, information about the parse.  Records at typePtr

 *	the character type of the non-whitespace character that terminated

 *	the scan.

 *

 * Side effects:

 *	None.

 *

 *----------------------------------------------------------------------

 */

int

TclParseWhiteSpace(src, numBytes, parsePtr, typePtr)

    CONST char *src;		/* First character to parse. */

    register int numBytes;	/* Max number of bytes to scan. */

    Tcl_Parse *parsePtr;	/* Information about parse in progress.

				 * Updated if parsing indicates

				 * an incomplete command. */

    char *typePtr;		/* Points to location to store character

				 * type of character that ends run

				 * of whitespace */

{

    register char type = TYPE_NORMAL;

    register CONST char *p = src;

    while (1) {

	while (numBytes && ((type = CHAR_TYPE(*p)) & TYPE_SPACE)) {

	    numBytes--; p++;

	}

	if (numBytes && (type & TYPE_SUBS)) {

	    if (*p != '\\') {

		break;

	    }

	    if (--numBytes == 0) {

		break;

	    }

	    if (p[1] != '\n') {

		break;

	    }

	    p+=2;

	    if (--numBytes == 0) {

		parsePtr->incomplete = 1;

		break;

	    }

	    continue;

	}

	break;

    }

    *typePtr = type;

    return (p - src);

}

/*

 *----------------------------------------------------------------------

 *

 * TclParseHex --

 *

 *	Scans a hexadecimal number as a Tcl_UniChar value.

 *	(e.g., for parsing \x and \u escape sequences).

 *	At most numBytes bytes are scanned.

 *

 * Results:

 *	The numeric value is stored in *resultPtr.

 *	Returns the number of bytes consumed.

 *

 * Notes:

 *	Relies on the following properties of the ASCII

 *	character set, with which UTF-8 is compatible:

 *

 *	The digits '0' .. '9' and the letters 'A' .. 'Z' and 'a' .. 'z' 

 *	occupy consecutive code points, and '0' < 'A' < 'a'.

 *

 *----------------------------------------------------------------------

 */

int

TclParseHex(src, numBytes, resultPtr)

    CONST char *src;		/* First character to parse. */

    int numBytes;		/* Max number of byes to scan */

    Tcl_UniChar *resultPtr;	/* Points to storage provided by

				 * caller where the Tcl_UniChar

				 * resulting from the conversion is

				 * to be written. */

{

    Tcl_UniChar result = 0;

    register CONST char *p = src;

    while (numBytes--) {

	unsigned char digit = UCHAR(*p);

	if (!isxdigit(digit))

	    break;

	++p;

	result <<= 4;

	if (digit >= 'a') {

	    result |= (10 + digit - 'a');

	} else if (digit >= 'A') {

	    result |= (10 + digit - 'A');

	} else {

	    result |= (digit - '0');

	}

    }