/*

 * Licensed to the Apache Software Foundation (ASF) under one or more

 * contributor license agreements.  See the NOTICE file distributed with

 * this work for additional information regarding copyright ownership.

 * The ASF licenses this file to You under the Apache License, Version 2.0

 * (the "License"); you may not use this file except in compliance with

 * the License.  You may obtain a copy of the License at

 * 

 *      http://www.apache.org/licenses/LICENSE-2.0

 * 

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

/**

 *  $Id: XMLRecognizer.cpp 555320 2007-07-11 16:05:13Z amassari $

 */

// ---------------------------------------------------------------------------

//  Includes

// ---------------------------------------------------------------------------

#include <xercesc/framework/XMLRecognizer.hpp>

#include <xercesc/util/RuntimeException.hpp>

#include <xercesc/util/XMLString.hpp>

XERCES_CPP_NAMESPACE_BEGIN

// ---------------------------------------------------------------------------

//  Local data

//

//  gEncodingNameMap

//      This array maps the Encodings enum values to their canonical names.

//      Be sure to keep this in sync with that enum!

// ---------------------------------------------------------------------------

static const XMLCh* gEncodingNameMap[XMLRecognizer::Encodings_Count] =

{

    XMLUni::fgEBCDICEncodingString

    , XMLUni::fgUCS4BEncodingString

    , XMLUni::fgUCS4LEncodingString

    , XMLUni::fgUSASCIIEncodingString

    , XMLUni::fgUTF8EncodingString

    , XMLUni::fgUTF16BEncodingString

    , XMLUni::fgUTF16LEncodingString

    , XMLUni::fgXMLChEncodingString

};

// ---------------------------------------------------------------------------

//  XMLRecognizer: Public, const static data

//

//  gXXXPre

//  gXXXPreLen

//      The byte sequence prefixes for all of the encodings that we can

//      auto sense. Also included is the length of each sequence.

// ---------------------------------------------------------------------------

const char           XMLRecognizer::fgASCIIPre[]  = { 0x3C, 0x3F, 0x78, 0x6D, 0x6C, 0x20 };

const XMLSize_t      XMLRecognizer::fgASCIIPreLen = 6;

const XMLByte        XMLRecognizer::fgEBCDICPre[] = { 0x4C, 0x6F, 0xA7, 0x94, 0x93, 0x40 };

const XMLSize_t      XMLRecognizer::fgEBCDICPreLen = 6;

const XMLByte        XMLRecognizer::fgUTF16BPre[] = { 0x00, 0x3C, 0x00, 0x3F, 0x00, 0x78, 0x00, 0x6D, 0x00, 0x6C, 0x00, 0x20 };

const XMLByte        XMLRecognizer::fgUTF16LPre[] = { 0x3C, 0x00, 0x3F, 0x00, 0x78, 0x00, 0x6D, 0x00, 0x6C, 0x00, 0x20, 0x00 };

const XMLSize_t      XMLRecognizer::fgUTF16PreLen = 12;

const XMLByte        XMLRecognizer::fgUCS4BPre[]  =

{

        0x00, 0x00, 0x00, 0x3C, 0x00, 0x00, 0x00, 0x3F

    ,   0x00, 0x00, 0x00, 0x78, 0x00, 0x00, 0x00, 0x6D

    ,   0x00, 0x00, 0x00, 0x6C, 0x00, 0x00, 0x00, 0x20

};

const XMLByte        XMLRecognizer::fgUCS4LPre[]  =

{

        0x3C, 0x00, 0x00, 0x00, 0x3F, 0x00, 0x00, 0x00

    ,   0x78, 0x00, 0x00, 0x00, 0x6D, 0x00, 0x00, 0x00

    ,   0x6C, 0x00, 0x00, 0x00, 0x20, 0x00, 0x00, 0x00

};

const XMLSize_t      XMLRecognizer::fgUCS4PreLen = 24;

const char           XMLRecognizer::fgUTF8BOM[] = {(char)0xEF, (char)0xBB, (char)0xBF};

const XMLSize_t      XMLRecognizer::fgUTF8BOMLen = 3;

// ---------------------------------------------------------------------------

//  XMLRecognizer: Encoding recognition methods

// ---------------------------------------------------------------------------

XMLRecognizer::Encodings

XMLRecognizer::basicEncodingProbe(  const   XMLByte* const  rawBuffer

                                    , const XMLSize_t       rawByteCount)

{

    //

    //  As an optimization to check the 90% case, check first for the ASCII

    //  sequence '<?xml', which means its either US-ASCII, UTF-8, or some

    //  other encoding that we don't do manually but which happens to share

    //  the US-ASCII code points for these characters. So just return UTF-8

    //  to get us through the first line.

    //

    if (rawByteCount >= fgASCIIPreLen)

    {

        if (!memcmp(rawBuffer, fgASCIIPre, fgASCIIPreLen))

            return UTF_8;

    }

    //

    //  If the count of raw bytes is less than 2, it cannot be anything

    //  we understand, so return UTF-8 as a fallback.

    //

    if (rawByteCount < 2)

        return UTF_8;

    //  

    //  We have two to four bytes, so lets check for a UTF-16 BOM. That

    //  is quick to check and enough to identify two major encodings.   

    // 

    if (rawByteCount < 4)

    {

        if ((rawBuffer[0] == 0xFE) && (rawBuffer[1] == 0xFF))

            return UTF_16B;

        else if ((rawBuffer[0] == 0xFF) && (rawBuffer[1] == 0xFE))

            return UTF_16L;

        else 

            return UTF_8;

    }

    /***

     *    F.1 Detection Without External Encoding Information

     *

     *    Because each XML entity not accompanied by external encoding information and 

     *    not in UTF-8 or UTF-16 encoding must begin with an XML encoding declaration, 

     *    in which the first characters must be '<?xml', any conforming processor can detect, 

     *    after two to four octets of input, which of the following cases apply. 

     *

     *    In reading this list, it may help to know that in UCS-4, '<' is "#x0000003C" and 

     *    '?' is "#x0000003F", and the Byte Order Mark required of UTF-16 data streams is 

     *    "#xFEFF". The notation ## is used to denote any byte value except that two consecutive 

     *    ##s cannot be both 00.

     *

     *    With a Byte Order Mark:

     *

     *    00 00 FE FF           UCS-4,    big-endian machine    (1234 order) 

     *    FF FE 00 00           UCS-4,    little-endian machine (4321 order) 

     *    00 00 FF FE           UCS-4,    unusual octet order   (2143) 

     *    FE FF 00 00           UCS-4,    unusual octet order   (3412) 

     *    FE FF ## ##           UTF-16,   big-endian 

     *    FF FE ## ##           UTF-16,   little-endian 

     *    EF BB BF              UTF-8 

     *

     ***/

    //

    //  We have at least four bytes, so we can check all BOM

    //  for UCS-4BE, UCS-4LE, UTF-16BE and UTF-16LE as well.

    //

    if ((rawBuffer[0] == 0x00) && (rawBuffer[1] == 0x00) && (rawBuffer[2] == 0xFE) && (rawBuffer[3] == 0xFF))

        return UCS_4B;

    else if ((rawBuffer[0] == 0xFF) && (rawBuffer[1] == 0xFE) && (rawBuffer[2] == 0x00) && (rawBuffer[3] == 0x00))

        return UCS_4L;

    else if ((rawBuffer[0] == 0xFE) && (rawBuffer[1] == 0xFF))

        return UTF_16B;

    else if ((rawBuffer[0] == 0xFF) && (rawBuffer[1] == 0xFE))

        return UTF_16L;

    //

    //  We have at least 4 bytes. So lets check the 4 byte sequences that

    //  indicate other UTF-16 and UCS encodings.

    //

    if ((rawBuffer[0] == 0x00) || (rawBuffer[0] == 0x3C))

    {

        if (rawByteCount >= fgUCS4PreLen && !memcmp(rawBuffer, fgUCS4BPre, fgUCS4PreLen))

            return UCS_4B;

        else if (rawByteCount >= fgUCS4PreLen && !memcmp(rawBuffer, fgUCS4LPre, fgUCS4PreLen))

            return UCS_4L;

        else if (rawByteCount >= fgUTF16PreLen && !memcmp(rawBuffer, fgUTF16BPre, fgUTF16PreLen))

            return UTF_16B;

        else if (rawByteCount >= fgUTF16PreLen && !memcmp(rawBuffer, fgUTF16LPre, fgUTF16PreLen))

            return UTF_16L;

    }

    //

    //  See if we have enough bytes to possibly match the EBCDIC prefix.

    //  If so, try it.

    //

    if (rawByteCount > fgEBCDICPreLen)

    {

        if (!memcmp(rawBuffer, fgEBCDICPre, fgEBCDICPreLen))

            return EBCDIC;

    }

    //

    //  Does not seem to be anything we know, so go with UTF-8 to get at

    //  least through the first line and see what it really is.

    //

    return UTF_8;

}

XMLRecognizer::Encodings

XMLRecognizer::encodingForName(const XMLCh* const encName)

{

    //

    //  Compare the passed string, assume input string is already uppercased,

    //  to the variations that we recognize.

    //

    //  !!NOTE: Note that we don't handle EBCDIC here because we don't handle

    //  that one ourselves. It is allowed to fall into 'other'.

    //

    if (encName == XMLUni::fgXMLChEncodingString ||

        !XMLString::compareString(encName, XMLUni::fgXMLChEncodingString))

    {

        return XMLRecognizer::XERCES_XMLCH;

    }

    else if (!XMLString::compareString(encName, XMLUni::fgUTF8EncodingString)

         ||  !XMLString::compareString(encName, XMLUni::fgUTF8EncodingString2))

    {

        return XMLRecognizer::UTF_8;

    }

    else if (!XMLString::compareString(encName, XMLUni::fgUSASCIIEncodingString)

         ||  !XMLString::compareString(encName, XMLUni::fgUSASCIIEncodingString2)

         ||  !XMLString::compareString(encName, XMLUni::fgUSASCIIEncodingString3)

         ||  !XMLString::compareString(encName, XMLUni::fgUSASCIIEncodingString4))

    {

        return XMLRecognizer::US_ASCII;

    }

    else if (!XMLString::compareString(encName, XMLUni::fgUTF16LEncodingString)

         ||  !XMLString::compareString(encName, XMLUni::fgUTF16LEncodingString2))

    {

        return XMLRecognizer::UTF_16L;

    }

    else if (!XMLString::compareString(encName, XMLUni::fgUTF16BEncodingString)

         ||  !XMLString::compareString(encName, XMLUni::fgUTF16BEncodingString2))

    {

        return XMLRecognizer::UTF_16B;

    }

    else if (!XMLString::compareString(encName, XMLUni::fgUTF16EncodingString))

    {

        return XMLPlatformUtils::fgXMLChBigEndian?XMLRecognizer::UTF_16B:XMLRecognizer::UTF_16L;

    }

    else if (!XMLString::compareString(encName, XMLUni::fgUCS4LEncodingString)

         ||  !XMLString::compareString(encName, XMLUni::fgUCS4LEncodingString2))

    {

        return XMLRecognizer::UCS_4L;

    }

    else if (!XMLString::compareString(encName, XMLUni::fgUCS4BEncodingString)

         ||  !XMLString::compareString(encName, XMLUni::fgUCS4BEncodingString2))

    {

        return XMLRecognizer::UCS_4B;

    }

    else if (!XMLString::compareString(encName, XMLUni::fgUCS4EncodingString))

    {

        return XMLPlatformUtils::fgXMLChBigEndian?XMLRecognizer::UCS_4B:XMLRecognizer::UCS_4L;

    }

    // Return 'other' since we don't recognizer it

    return XMLRecognizer::OtherEncoding;

}

const XMLCh*

XMLRecognizer::nameForEncoding(const XMLRecognizer::Encodings theEncoding

                               , MemoryManager* const manager)

{

    if (theEncoding >= Encodings_Count)

        ThrowXMLwithMemMgr(RuntimeException, XMLExcepts::XMLRec_UnknownEncoding, manager);

    return gEncodingNameMap[theEncoding];

}

XERCES_CPP_NAMESPACE_END