104 lines
4.4 KiB
C
104 lines
4.4 KiB
C
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// Copyright (c) 2011 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef BASE_STRINGS_UTF_STRING_CONVERSION_UTILS_H_
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#define BASE_STRINGS_UTF_STRING_CONVERSION_UTILS_H_
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// Low-level UTF handling functions. Most code will want to use the functions
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// in utf_string_conversions.h
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#include <stddef.h>
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#include <stdint.h>
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#include "base/base_export.h"
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#include "base/strings/string16.h"
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namespace base {
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inline bool IsValidCodepoint(uint32_t code_point) {
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// Excludes code points that are not Unicode scalar values, i.e.
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// surrogate code points ([0xD800, 0xDFFF]). Additionally, excludes
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// code points larger than 0x10FFFF (the highest codepoint allowed).
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// Non-characters and unassigned code points are allowed.
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// https://unicode.org/glossary/#unicode_scalar_value
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return code_point < 0xD800u ||
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(code_point >= 0xE000u && code_point <= 0x10FFFFu);
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}
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inline bool IsValidCharacter(uint32_t code_point) {
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// Excludes non-characters (U+FDD0..U+FDEF, and all code points
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// ending in 0xFFFE or 0xFFFF) from the set of valid code points.
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// https://unicode.org/faq/private_use.html#nonchar1
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return code_point < 0xD800u || (code_point >= 0xE000u &&
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code_point < 0xFDD0u) || (code_point > 0xFDEFu &&
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code_point <= 0x10FFFFu && (code_point & 0xFFFEu) != 0xFFFEu);
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}
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// ReadUnicodeCharacter --------------------------------------------------------
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// Reads a UTF-8 stream, placing the next code point into the given output
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// |*code_point|. |src| represents the entire string to read, and |*char_index|
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// is the character offset within the string to start reading at. |*char_index|
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// will be updated to index the last character read, such that incrementing it
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// (as in a for loop) will take the reader to the next character.
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//
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// Returns true on success. On false, |*code_point| will be invalid.
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BASE_EXPORT bool ReadUnicodeCharacter(const char* src,
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int32_t src_len,
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int32_t* char_index,
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uint32_t* code_point_out);
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// Reads a UTF-16 character. The usage is the same as the 8-bit version above.
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BASE_EXPORT bool ReadUnicodeCharacter(const char16* src,
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int32_t src_len,
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int32_t* char_index,
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uint32_t* code_point);
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#if defined(WCHAR_T_IS_UTF32)
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// Reads UTF-32 character. The usage is the same as the 8-bit version above.
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BASE_EXPORT bool ReadUnicodeCharacter(const wchar_t* src,
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int32_t src_len,
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int32_t* char_index,
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uint32_t* code_point);
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#endif // defined(WCHAR_T_IS_UTF32)
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// WriteUnicodeCharacter -------------------------------------------------------
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// Appends a UTF-8 character to the given 8-bit string. Returns the number of
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// bytes written.
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BASE_EXPORT size_t WriteUnicodeCharacter(uint32_t code_point,
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std::string* output);
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// Appends the given code point as a UTF-16 character to the given 16-bit
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// string. Returns the number of 16-bit values written.
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BASE_EXPORT size_t WriteUnicodeCharacter(uint32_t code_point, string16* output);
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#if defined(WCHAR_T_IS_UTF32)
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// Appends the given UTF-32 character to the given 32-bit string. Returns the
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// number of 32-bit values written.
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inline size_t WriteUnicodeCharacter(uint32_t code_point, std::wstring* output) {
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// This is the easy case, just append the character.
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output->push_back(code_point);
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return 1;
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}
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#endif // defined(WCHAR_T_IS_UTF32)
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// Generalized Unicode converter -----------------------------------------------
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// Guesses the length of the output in UTF-8 in bytes, clears that output
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// string, and reserves that amount of space. We assume that the input
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// character types are unsigned, which will be true for UTF-16 and -32 on our
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// systems.
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template<typename CHAR>
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void PrepareForUTF8Output(const CHAR* src, size_t src_len, std::string* output);
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// Prepares an output buffer (containing either UTF-16 or -32 data) given some
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// UTF-8 input that will be converted to it. See PrepareForUTF8Output().
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template<typename STRING>
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void PrepareForUTF16Or32Output(const char* src, size_t src_len, STRING* output);
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} // namespace base
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#endif // BASE_STRINGS_UTF_STRING_CONVERSION_UTILS_H_
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