325 lines
9.3 KiB
C++
325 lines
9.3 KiB
C++
/*
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* Copyright (C) 2011 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "utf.h"
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#include <android-base/logging.h>
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#include <android-base/stringprintf.h>
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#include <android-base/strings.h>
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#include "base/casts.h"
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#include "utf-inl.h"
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namespace art {
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using android::base::StringAppendF;
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// This is used only from debugger and test code.
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size_t CountModifiedUtf8Chars(const char* utf8) {
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return CountModifiedUtf8Chars(utf8, strlen(utf8));
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}
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/*
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* This does not validate UTF8 rules (nor did older code). But it gets the right answer
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* for valid UTF-8 and that's fine because it's used only to size a buffer for later
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* conversion.
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*
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* Modified UTF-8 consists of a series of bytes up to 21 bit Unicode code points as follows:
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* U+0001 - U+007F 0xxxxxxx
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* U+0080 - U+07FF 110xxxxx 10xxxxxx
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* U+0800 - U+FFFF 1110xxxx 10xxxxxx 10xxxxxx
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* U+10000 - U+1FFFFF 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
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*
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* U+0000 is encoded using the 2nd form to avoid nulls inside strings (this differs from
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* standard UTF-8).
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* The four byte encoding converts to two utf16 characters.
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*/
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size_t CountModifiedUtf8Chars(const char* utf8, size_t byte_count) {
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DCHECK_LE(byte_count, strlen(utf8));
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size_t len = 0;
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const char* end = utf8 + byte_count;
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for (; utf8 < end; ++utf8) {
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int ic = *utf8;
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len++;
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if (LIKELY((ic & 0x80) == 0)) {
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// One-byte encoding.
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continue;
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}
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// Two- or three-byte encoding.
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utf8++;
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if ((ic & 0x20) == 0) {
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// Two-byte encoding.
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continue;
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}
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utf8++;
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if ((ic & 0x10) == 0) {
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// Three-byte encoding.
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continue;
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}
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// Four-byte encoding: needs to be converted into a surrogate
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// pair.
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utf8++;
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len++;
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}
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return len;
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}
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// This is used only from debugger and test code.
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void ConvertModifiedUtf8ToUtf16(uint16_t* utf16_data_out, const char* utf8_data_in) {
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while (*utf8_data_in != '\0') {
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const uint32_t ch = GetUtf16FromUtf8(&utf8_data_in);
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const uint16_t leading = GetLeadingUtf16Char(ch);
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const uint16_t trailing = GetTrailingUtf16Char(ch);
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*utf16_data_out++ = leading;
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if (trailing != 0) {
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*utf16_data_out++ = trailing;
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}
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}
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}
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void ConvertModifiedUtf8ToUtf16(uint16_t* utf16_data_out, size_t out_chars,
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const char* utf8_data_in, size_t in_bytes) {
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const char *in_start = utf8_data_in;
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const char *in_end = utf8_data_in + in_bytes;
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uint16_t *out_p = utf16_data_out;
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if (LIKELY(out_chars == in_bytes)) {
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// Common case where all characters are ASCII.
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for (const char *p = in_start; p < in_end;) {
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// Safe even if char is signed because ASCII characters always have
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// the high bit cleared.
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*out_p++ = dchecked_integral_cast<uint16_t>(*p++);
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}
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return;
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}
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// String contains non-ASCII characters.
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for (const char *p = in_start; p < in_end;) {
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const uint32_t ch = GetUtf16FromUtf8(&p);
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const uint16_t leading = GetLeadingUtf16Char(ch);
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const uint16_t trailing = GetTrailingUtf16Char(ch);
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*out_p++ = leading;
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if (trailing != 0) {
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*out_p++ = trailing;
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}
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}
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}
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void ConvertUtf16ToModifiedUtf8(char* utf8_out, size_t byte_count,
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const uint16_t* utf16_in, size_t char_count) {
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if (LIKELY(byte_count == char_count)) {
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// Common case where all characters are ASCII.
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const uint16_t *utf16_end = utf16_in + char_count;
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for (const uint16_t *p = utf16_in; p < utf16_end;) {
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*utf8_out++ = dchecked_integral_cast<char>(*p++);
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}
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return;
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}
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// String contains non-ASCII characters.
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while (char_count--) {
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const uint16_t ch = *utf16_in++;
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if (ch > 0 && ch <= 0x7f) {
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*utf8_out++ = ch;
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} else {
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// Char_count == 0 here implies we've encountered an unpaired
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// surrogate and we have no choice but to encode it as 3-byte UTF
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// sequence. Note that unpaired surrogates can occur as a part of
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// "normal" operation.
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if ((ch >= 0xd800 && ch <= 0xdbff) && (char_count > 0)) {
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const uint16_t ch2 = *utf16_in;
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// Check if the other half of the pair is within the expected
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// range. If it isn't, we will have to emit both "halves" as
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// separate 3 byte sequences.
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if (ch2 >= 0xdc00 && ch2 <= 0xdfff) {
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utf16_in++;
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char_count--;
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const uint32_t code_point = (ch << 10) + ch2 - 0x035fdc00;
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*utf8_out++ = (code_point >> 18) | 0xf0;
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*utf8_out++ = ((code_point >> 12) & 0x3f) | 0x80;
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*utf8_out++ = ((code_point >> 6) & 0x3f) | 0x80;
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*utf8_out++ = (code_point & 0x3f) | 0x80;
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continue;
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}
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}
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if (ch > 0x07ff) {
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// Three byte encoding.
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*utf8_out++ = (ch >> 12) | 0xe0;
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*utf8_out++ = ((ch >> 6) & 0x3f) | 0x80;
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*utf8_out++ = (ch & 0x3f) | 0x80;
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} else /*(ch > 0x7f || ch == 0)*/ {
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// Two byte encoding.
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*utf8_out++ = (ch >> 6) | 0xc0;
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*utf8_out++ = (ch & 0x3f) | 0x80;
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}
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}
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}
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}
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int32_t ComputeUtf16HashFromModifiedUtf8(const char* utf8, size_t utf16_length) {
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uint32_t hash = 0;
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while (utf16_length != 0u) {
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const uint32_t pair = GetUtf16FromUtf8(&utf8);
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const uint16_t first = GetLeadingUtf16Char(pair);
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hash = hash * 31 + first;
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--utf16_length;
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const uint16_t second = GetTrailingUtf16Char(pair);
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if (second != 0) {
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hash = hash * 31 + second;
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DCHECK_NE(utf16_length, 0u);
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--utf16_length;
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}
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}
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return static_cast<int32_t>(hash);
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}
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uint32_t ComputeModifiedUtf8Hash(const char* chars) {
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uint32_t hash = 0;
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while (*chars != '\0') {
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hash = hash * 31 + static_cast<uint8_t>(*chars);
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++chars;
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}
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return hash;
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}
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int CompareModifiedUtf8ToUtf16AsCodePointValues(const char* utf8, const uint16_t* utf16,
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size_t utf16_length) {
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for (;;) {
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if (*utf8 == '\0') {
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return (utf16_length == 0) ? 0 : -1;
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} else if (utf16_length == 0) {
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return 1;
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}
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const uint32_t pair = GetUtf16FromUtf8(&utf8);
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// First compare the leading utf16 char.
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const uint16_t lhs = GetLeadingUtf16Char(pair);
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const uint16_t rhs = *utf16++;
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--utf16_length;
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if (lhs != rhs) {
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return lhs > rhs ? 1 : -1;
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}
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// Then compare the trailing utf16 char. First check if there
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// are any characters left to consume.
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const uint16_t lhs2 = GetTrailingUtf16Char(pair);
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if (lhs2 != 0) {
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if (utf16_length == 0) {
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return 1;
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}
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const uint16_t rhs2 = *utf16++;
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--utf16_length;
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if (lhs2 != rhs2) {
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return lhs2 > rhs2 ? 1 : -1;
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}
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}
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}
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}
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size_t CountUtf8Bytes(const uint16_t* chars, size_t char_count) {
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size_t result = 0;
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const uint16_t *end = chars + char_count;
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while (chars < end) {
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const uint16_t ch = *chars++;
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if (LIKELY(ch != 0 && ch < 0x80)) {
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result++;
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continue;
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}
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if (ch < 0x800) {
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result += 2;
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continue;
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}
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if (ch >= 0xd800 && ch < 0xdc00) {
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if (chars < end) {
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const uint16_t ch2 = *chars;
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// If we find a properly paired surrogate, we emit it as a 4 byte
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// UTF sequence. If we find an unpaired leading or trailing surrogate,
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// we emit it as a 3 byte sequence like would have done earlier.
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if (ch2 >= 0xdc00 && ch2 < 0xe000) {
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chars++;
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result += 4;
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continue;
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}
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}
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}
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result += 3;
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}
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return result;
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}
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static inline constexpr bool NeedsEscaping(uint16_t ch) {
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return (ch < ' ' || ch > '~');
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}
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std::string PrintableChar(uint16_t ch) {
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std::string result;
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result += '\'';
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if (NeedsEscaping(ch)) {
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StringAppendF(&result, "\\u%04x", ch);
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} else {
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result += static_cast<std::string::value_type>(ch);
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}
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result += '\'';
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return result;
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}
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std::string PrintableString(const char* utf8) {
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std::string result;
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result += '"';
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const char* p = utf8;
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size_t char_count = CountModifiedUtf8Chars(p);
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for (size_t i = 0; i < char_count; ++i) {
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uint32_t ch = GetUtf16FromUtf8(&p);
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if (ch == '\\') {
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result += "\\\\";
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} else if (ch == '\n') {
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result += "\\n";
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} else if (ch == '\r') {
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result += "\\r";
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} else if (ch == '\t') {
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result += "\\t";
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} else {
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const uint16_t leading = GetLeadingUtf16Char(ch);
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if (NeedsEscaping(leading)) {
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StringAppendF(&result, "\\u%04x", leading);
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} else {
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result += static_cast<std::string::value_type>(leading);
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}
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const uint32_t trailing = GetTrailingUtf16Char(ch);
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if (trailing != 0) {
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// All high surrogates will need escaping.
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StringAppendF(&result, "\\u%04x", trailing);
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// Account for the surrogate pair.
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++i;
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DCHECK_LT(i, char_count);
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}
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}
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}
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result += '"';
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return result;
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}
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} // namespace art
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