142 lines
4.7 KiB
C++
142 lines
4.7 KiB
C++
// Filename: stringDecoder.cxx
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// Created by: drose (11Feb02)
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//
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////////////////////////////////////////////////////////////////////
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//
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// PANDA 3D SOFTWARE
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// Copyright (c) 2001, Disney Enterprises, Inc. All rights reserved
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//
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// All use of this software is subject to the terms of the Panda 3d
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// Software license. You should have received a copy of this license
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// along with this source code; you will also find a current copy of
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// the license at http://www.panda3d.org/license.txt .
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//
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// To contact the maintainers of this program write to
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// panda3d@yahoogroups.com .
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//
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////////////////////////////////////////////////////////////////////
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#include "stringDecoder.h"
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#include "config_express.h"
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////////////////////////////////////////////////////////////////////
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// Function: StringDecoder::Destructor
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// Access: Public, Virtual
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// Description:
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////////////////////////////////////////////////////////////////////
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StringDecoder::
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~StringDecoder() {
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}
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////////////////////////////////////////////////////////////////////
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// Function: StringDecoder::get_next_character
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// Access: Public, Virtual
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// Description: Returns the next character in sequence.
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////////////////////////////////////////////////////////////////////
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int StringDecoder::
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get_next_character() {
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if (test_eof()) {
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return -1;
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}
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return (unsigned char)_input[_p++];
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}
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/*
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In UTF-8, each 16-bit Unicode character is encoded as a sequence of
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one, two, or three 8-bit bytes, depending on the value of the
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character. The following table shows the format of such UTF-8 byte
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sequences (where the "free bits" shown by x's in the table are
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combined in the order shown, and interpreted from most significant to
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least significant):
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Binary format of bytes in sequence:
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Number of Maximum expressible
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1st byte 2nd byte 3rd byte free bits: Unicode value:
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0xxxxxxx 7 007F hex (127)
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110xxxxx 10xxxxxx (5+6)=11 07FF hex (2047)
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1110xxxx 10xxxxxx 10xxxxxx (4+6+6)=16 FFFF hex (65535)
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The value of each individual byte indicates its UTF-8 function, as follows:
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00 to 7F hex (0 to 127): first and only byte of a sequence.
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80 to BF hex (128 to 191): continuing byte in a multi-byte sequence.
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C2 to DF hex (194 to 223): first byte of a two-byte sequence.
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E0 to EF hex (224 to 239): first byte of a three-byte sequence.
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*/
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////////////////////////////////////////////////////////////////////
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// Function: StringUtf8Decoder::get_next_character
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// Access: Public, Virtual
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// Description: Returns the next character in sequence.
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////////////////////////////////////////////////////////////////////
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int StringUtf8Decoder::
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get_next_character() {
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unsigned int result;
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while (!test_eof()) {
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result = (unsigned char)_input[_p++];
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if ((result & 0x80) == 0) {
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// A 7-bit ascii value in one byte.
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return result;
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} if ((result & 0xe0) == 0xc0) {
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// First byte of two.
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unsigned int two = 0;
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if (test_eof()) {
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express_cat.warning()
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<< "utf-8 encoded string ends abruptly.\n";
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return -1;
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}
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two = (unsigned char)_input[_p++];
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result = ((result & 0x1f) << 6) | (two & 0x3f);
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return result;
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} else if ((result & 0xf0) == 0xe0) {
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// First byte of three.
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if (test_eof()) {
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express_cat.warning()
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<< "utf-8 encoded string ends abruptly.\n";
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return -1;
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}
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unsigned int two = (unsigned char)_input[_p++];
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if (test_eof()) {
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express_cat.warning()
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<< "utf-8 encoded string ends abruptly.\n";
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return -1;
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}
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unsigned int three = (unsigned char)_input[_p++];
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result = ((result & 0x0f) << 12) | ((two & 0x3f) << 6) | (three & 0x3f);
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return result;
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}
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// Otherwise--the high bit is set but it is not one of the
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// introductory utf-8 bytes--we have an error.
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express_cat.warning()
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<< "Non utf-8 byte in string: 0x" << hex << result << dec << "\n";
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}
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// End of string reached.
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return -1;
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}
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////////////////////////////////////////////////////////////////////
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// Function: StringUnicodeDecoder::get_next_character
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// Access: Public, Virtual
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// Description: Returns the next character in sequence.
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////////////////////////////////////////////////////////////////////
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int StringUnicodeDecoder::
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get_next_character() {
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if (test_eof()) {
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return -1;
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}
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unsigned int high = (unsigned char)_input[_p++];
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if (test_eof()) {
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express_cat.warning()
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<< "Unicode-encoded string has odd number of bytes.\n";
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return -1;
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}
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unsigned int low = (unsigned char)_input[_p++];
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return ((high << 8) | low);
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}
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