added Encodings library

Encodings/include/Poco/DoubleByteEncoding.h

@@ -0,0 +1,122 @@
+//
+// DoubleByteEncoding.h
+//
+// Library: Encodings
+// Package: Encodings
+// Module:  DoubleByteEncoding
+//
+// Definition of the DoubleByteEncoding class.
+//
+// Copyright (c) 2018, Applied Informatics Software Engineering GmbH.
+// and Contributors.
+//
+// SPDX-License-Identifier:	BSL-1.0
+//
+
+
+#ifndef Encodings_DoubleByteEncoding_INCLUDED
+#define Encodings_DoubleByteEncoding_INCLUDED
+
+
+#include "Poco/Encodings.h"
+#include "Poco/TextEncoding.h"
+
+
+namespace Poco {
+
+
+class Encodings_API DoubleByteEncoding: public TextEncoding
+	/// This abstract class is a base class for various double-byte character
+	/// set (DBCS) encodings.
+	///
+	/// Double-byte encodings are variants of multi-byte encodings
+	/// where (Unicode) each code point is represented by one or
+	/// two bytes. Unicode code points are restricted to the
+	/// Basic Multilingual Plane.
+	///
+	/// Subclasses must provide encoding names, a static CharacterMap, as well
+	/// as static Mapping and reverse Mapping tables, and provide these to the
+	/// DoubleByteEncoding constructor.
+{
+public:
+	struct Mapping
+	{
+		Poco::UInt16 from;
+		Poco::UInt16 to;
+	};
+
+	// TextEncoding
+	const char* canonicalName() const;
+	bool isA(const std::string& encodingName) const;
+	const CharacterMap& characterMap() const;
+	int convert(const unsigned char* bytes) const;
+	int convert(int ch, unsigned char* bytes, int length) const;
+	int queryConvert(const unsigned char* bytes, int length) const;
+	int sequenceLength(const unsigned char* bytes, int length) const;
+
+protected:
+	DoubleByteEncoding(const char** names, const TextEncoding::CharacterMap& charMap, const Mapping mappingTable[], std::size_t mappingTableSize, const Mapping reverseMappingTable[], std::size_t reverseMappingTableSize);
+		/// Creates a DoubleByteEncoding using the given mapping and reverse-mapping tables.
+		///
+		/// names must be a static array declared in the derived class,
+		/// containing the names of this encoding, declared as:
+		///
+		///     const char* MyEncoding::_names[] =
+		///     {
+		///         "myencoding",
+		///         "MyEncoding",
+		///         NULL
+		///     };
+		///
+		/// The first entry in names must be the canonical name.
+		///
+		/// charMap must be a static CharacterMap giving information about double-byte
+		/// character sequences.
+		///
+		/// For each mappingTable item, from must be a value in range 0x0100 to
+		//  0xFFFF for double-byte mappings, which the most significant (upper) byte
+		/// representing the first character in the sequence and the lower byte
+		/// representing the second character in the sequence.
+		///
+		/// For each reverseMappingTable item, from must be Unicode code point from the
+		/// Basic Multilingual Plane, and to is a one-byte or two-byte sequence.
+		/// As with mappingTable, a one-byte sequence is in range 0x00 to 0xFF, and a
+		/// two-byte sequence is in range 0x0100 to 0xFFFF.
+		///
+		/// Unicode code points are restricted to the Basic Multilingual Plane
+		/// (code points 0x0000 to 0xFFFF).
+		///
+		/// Items in both tables must be sorted by from, in ascending order.
+
+	~DoubleByteEncoding();
+		/// Destroys the DoubleByteEncoding.
+
+	int map(Poco::UInt16 encoded) const;
+		/// Maps a double-byte encoded character to its Unicode code point.
+		///
+		/// Returns the Unicode code point, or -1 if the encoded character is bad
+		/// and cannot be mapped.
+
+	int reverseMap(int cp) const;
+		/// Maps a Unicode code point to its double-byte representation.
+		///
+		/// Returns -1 if the code point cannot be mapped, otherwise
+		/// a value in range 0 to 0xFF for single-byte mappings, or
+		/// 0x0100 to 0xFFFF for double-byte mappings.
+
+private:
+	DoubleByteEncoding();
+
+	const char** _names;
+	const TextEncoding::CharacterMap& _charMap;
+	const Mapping* _mappingTable;
+	const std::size_t _mappingTableSize;
+	const Mapping* _reverseMappingTable;
+	const std::size_t _reverseMappingTableSize;
+};
+
+
+} // namespace Poco
+
+
+#endif // Encodings_DoubleByteEncoding_INCLUDED