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67 lines
2.4 KiB
C
67 lines
2.4 KiB
C
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/**
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* Copyright 2010 Google Inc.
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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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#ifndef UTIL_UTF8_PUBLIC_UNILIB_UTF8_UTILS_H_
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#define UTIL_UTF8_PUBLIC_UNILIB_UTF8_UTILS_H_
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// These definitions are self-contained and have no dependencies.
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// They are also exported from unilib.h for legacy reasons.
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#include "syntaxnet/base.h"
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#include "third_party/utf/utf.h"
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namespace UniLib {
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// Returns true if 'c' is in the range [0, 0xD800) or [0xE000, 0x10FFFF]
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// (i.e., is not a surrogate codepoint). See also
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// IsValidCodepoint(const char* src) in util/utf8/public/unilib.h.
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inline bool IsValidCodepoint(char32 c) {
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return (static_cast<uint32>(c) < 0xD800)
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|| (c >= 0xE000 && c <= 0x10FFFF);
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}
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// Returns true if 'str' is the start of a structurally valid UTF-8
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// sequence and is not a surrogate codepoint. Returns false if str.empty()
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// or if str.length() < UniLib::OneCharLen(str[0]). Otherwise, this function
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// will access 1-4 bytes of src, where n is UniLib::OneCharLen(src[0]).
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inline bool IsUTF8ValidCodepoint(StringPiece str) {
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char32 c;
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int consumed;
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// It's OK if str.length() > consumed.
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return !str.empty()
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&& isvalidcharntorune(str.data(), str.size(), &c, &consumed)
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&& IsValidCodepoint(c);
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}
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// Returns the length (number of bytes) of the Unicode code point
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// starting at src, based on inspecting just that one byte. This
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// requires that src point to a well-formed UTF-8 string; the result
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// is undefined otherwise.
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inline int OneCharLen(const char* src) {
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return "\1\1\1\1\1\1\1\1\1\1\1\1\2\2\3\4"[(*src & 0xFF) >> 4];
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}
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// Returns true if this byte is a trailing UTF-8 byte (10xx xxxx)
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inline bool IsTrailByte(char x) {
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// return (x & 0xC0) == 0x80;
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// Since trail bytes are always in [0x80, 0xBF], we can optimize:
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return static_cast<signed char>(x) < -0x40;
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}
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} // namespace UniLib
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#endif // UTIL_UTF8_PUBLIC_UNILIB_UTF8_UTILS_H_
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