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130 lines
4.2 KiB
C++
130 lines
4.2 KiB
C++
// © 2016 and later: Unicode, Inc. and others.
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// License & terms of use: http://www.unicode.org/copyright.html
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/*
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******************************************************************************
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*
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* Copyright (C) 1999-2012, International Business Machines
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* Corporation and others. All Rights Reserved.
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*
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******************************************************************************
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* file name: utf_impl.cpp
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* encoding: UTF-8
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* tab size: 8 (not used)
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* indentation:4
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*
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* created on: 1999sep13
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* created by: Markus W. Scherer
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*
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* This file provides implementation functions for macros in the utfXX.h
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* that would otherwise be too long as macros.
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*/
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#include "base/third_party/icu/icu_utf.h"
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namespace base_icu {
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// source/common/utf_impl.cpp
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static const UChar32 utf8_errorValue[6] = {
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// Same values as UTF8_ERROR_VALUE_1, UTF8_ERROR_VALUE_2, UTF_ERROR_VALUE,
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// but without relying on the obsolete unicode/utf_old.h.
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0x15, 0x9f, 0xffff, 0x10ffff};
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static UChar32 errorValue(int32_t count, int8_t strict) {
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if (strict >= 0) {
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return utf8_errorValue[count];
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} else if (strict == -3) {
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return 0xfffd;
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} else {
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return CBU_SENTINEL;
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}
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}
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/*
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* Handle the non-inline part of the U8_NEXT() and U8_NEXT_FFFD() macros
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* and their obsolete sibling UTF8_NEXT_CHAR_SAFE().
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*
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* U8_NEXT() supports NUL-terminated strings indicated via length<0.
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*
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* The "strict" parameter controls the error behavior:
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* <0 "Safe" behavior of U8_NEXT():
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* -1: All illegal byte sequences yield U_SENTINEL=-1.
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* -2: Same as -1, except for lenient treatment of surrogate code points as
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* legal. Some implementations use this for roundtripping of Unicode 16-bit
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* strings that are not well-formed UTF-16, that is, they contain
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* unpaired surrogates. -3: All illegal byte sequences yield U+FFFD. 0
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* Obsolete "safe" behavior of UTF8_NEXT_CHAR_SAFE(..., FALSE): All illegal
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* byte sequences yield a positive code point such that this result code
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* point would be encoded with the same number of bytes as the illegal
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* sequence. >0 Obsolete "strict" behavior of UTF8_NEXT_CHAR_SAFE(...,
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* TRUE): Same as the obsolete "safe" behavior, but non-characters are also
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* treated like illegal sequences.
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*
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* Note that a UBool is the same as an int8_t.
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*/
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UChar32 utf8_nextCharSafeBody(const uint8_t* s,
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int32_t* pi,
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int32_t length,
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UChar32 c,
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UBool strict) {
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// *pi is one after byte c.
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int32_t i = *pi;
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// length can be negative for NUL-terminated strings: Read and validate one
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// byte at a time.
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if (i == length || c > 0xf4) {
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// end of string, or not a lead byte
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} else if (c >= 0xf0) {
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// Test for 4-byte sequences first because
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// U8_NEXT() handles shorter valid sequences inline.
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uint8_t t1 = s[i], t2, t3;
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c &= 7;
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if (CBU8_IS_VALID_LEAD4_AND_T1(c, t1) && ++i != length &&
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(t2 = s[i] - 0x80) <= 0x3f && ++i != length &&
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(t3 = s[i] - 0x80) <= 0x3f) {
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++i;
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c = (c << 18) | ((t1 & 0x3f) << 12) | (t2 << 6) | t3;
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// strict: forbid non-characters like U+fffe
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if (strict <= 0 || !CBU_IS_UNICODE_NONCHAR(c)) {
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*pi = i;
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return c;
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}
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}
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} else if (c >= 0xe0) {
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c &= 0xf;
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if (strict != -2) {
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uint8_t t1 = s[i], t2;
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if (CBU8_IS_VALID_LEAD3_AND_T1(c, t1) && ++i != length &&
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(t2 = s[i] - 0x80) <= 0x3f) {
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++i;
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c = (c << 12) | ((t1 & 0x3f) << 6) | t2;
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// strict: forbid non-characters like U+fffe
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if (strict <= 0 || !CBU_IS_UNICODE_NONCHAR(c)) {
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*pi = i;
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return c;
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}
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}
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} else {
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// strict=-2 -> lenient: allow surrogates
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uint8_t t1 = s[i] - 0x80, t2;
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if (t1 <= 0x3f && (c > 0 || t1 >= 0x20) && ++i != length &&
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(t2 = s[i] - 0x80) <= 0x3f) {
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*pi = i + 1;
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return (c << 12) | (t1 << 6) | t2;
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}
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}
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} else if (c >= 0xc2) {
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uint8_t t1 = s[i] - 0x80;
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if (t1 <= 0x3f) {
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*pi = i + 1;
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return ((c - 0xc0) << 6) | t1;
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}
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} // else 0x80<=c<0xc2 is not a lead byte
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/* error handling */
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c = errorValue(i - *pi, strict);
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*pi = i;
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return c;
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}
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} // namespace base_icu
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