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107 lines
4.0 KiB
C++
107 lines
4.0 KiB
C++
//
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// TextEncoding.h
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//
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// $Id: //poco/Main/Foundation/include/Poco/TextEncoding.h#2 $
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//
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// Library: Foundation
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// Package: Text
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// Module: TextEncoding
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//
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// Definition of the abstract TextEncoding class.
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//
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// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
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// and Contributors.
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//
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// Permission is hereby granted, free of charge, to any person or organization
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// obtaining a copy of the software and accompanying documentation covered by
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// this license (the "Software") to use, reproduce, display, distribute,
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// execute, and transmit the Software, and to prepare derivative works of the
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// Software, and to permit third-parties to whom the Software is furnished to
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// do so, all subject to the following:
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//
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// The copyright notices in the Software and this entire statement, including
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// the above license grant, this restriction and the following disclaimer,
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// must be included in all copies of the Software, in whole or in part, and
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// all derivative works of the Software, unless such copies or derivative
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// works are solely in the form of machine-executable object code generated by
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// a source language processor.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
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// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
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// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
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// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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// DEALINGS IN THE SOFTWARE.
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//
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#ifndef Foundation_TextEncoding_INCLUDED
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#define Foundation_TextEncoding_INCLUDED
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#include "Poco/Foundation.h"
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namespace Poco {
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class Foundation_API TextEncoding
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/// An abstract base class for implementing text encodings
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/// like UTF-8 or ISO 8859-1.
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///
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/// Subclasses must override the characterMap() and convert()
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/// methods.
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{
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public:
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enum
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{
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MAX_SEQUENCE_LENGTH = 6 /// The maximum character byte sequence length supported.
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};
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typedef int CharacterMap[256];
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/// The map[b] member gives information about byte sequences
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/// whose first byte is b.
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/// If map[b] is c where c is >= 0, then b by itself encodes the Unicode scalar value c.
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/// If map[b] is -1, then the byte sequence is malformed.
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/// If map[b] is -n, where n >= 2, then b is the first byte of an n-byte
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/// sequence that encodes a single Unicode scalar value. Byte sequences up
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/// to 6 bytes in length are supported.
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virtual ~TextEncoding();
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/// Destroys the encoding.
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virtual const CharacterMap& characterMap() const = 0;
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/// Returns the CharacterMap for the encoding.
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/// The CharacterMap should be kept in a static member. As
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/// characterMap() can be called frequently, it should be
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/// implemented in such a way that it just returns a static
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/// map. If the map is built at runtime, this should be
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/// done in the constructor.
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virtual int convert(const unsigned char* bytes) const;
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/// The convert function is used to convert multibyte sequences;
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/// bytes will point to a byte sequence of n bytes where
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/// getCharacterMap()[*bytes] == -n.
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///
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/// The convert function must return the Unicode scalar value
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/// represented by this byte sequence or -1 if the byte sequence is malformed.
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/// The default implementation returns (int) bytes[0].
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virtual int convert(int ch, unsigned char* bytes, int length) const;
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/// Transform the Unicode character ch into the encoding's
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/// byte sequence. The method returns the number of bytes
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/// used. The method must not use more than length characters.
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/// Bytes and length can also be null - in this case only the number
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/// of bytes required to represent ch is returned.
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/// If the character cannot be converted, 0 is returned and
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/// the byte sequence remains unchanged.
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/// The default implementation simply returns 0.
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};
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} // namespace Poco
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#endif // Foundation_TextEncoding_INCLUDED
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