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152 lines
3.8 KiB
C++
152 lines
3.8 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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/* Character/text operations. */
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#ifndef mozilla_TextUtils_h
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#define mozilla_TextUtils_h
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#include "mozilla/Assertions.h"
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#include "mozilla/TypeTraits.h"
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namespace mozilla {
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namespace detail {
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template<typename Char>
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class MakeUnsignedChar
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: public MakeUnsigned<Char>
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{};
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template<>
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class MakeUnsignedChar<char16_t>
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{
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public:
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using Type = char16_t;
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};
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template<>
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class MakeUnsignedChar<char32_t>
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{
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public:
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using Type = char32_t;
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};
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} // namespace detail
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/** Returns true iff |aChar| is ASCII, i.e. in the range [0, 0x80). */
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template<typename Char>
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constexpr bool
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IsAscii(Char aChar)
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{
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using UnsignedChar = typename detail::MakeUnsignedChar<Char>::Type;
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auto uc = static_cast<UnsignedChar>(aChar);
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return uc < 0x80;
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}
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/**
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* Returns true iff |aChar| matches [a-z].
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*
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* This function is basically what you thought islower was, except its behavior
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* doesn't depend on the user's current locale.
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*/
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template<typename Char>
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constexpr bool
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IsAsciiLowercaseAlpha(Char aChar)
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{
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using UnsignedChar = typename detail::MakeUnsignedChar<Char>::Type;
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auto uc = static_cast<UnsignedChar>(aChar);
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return 'a' <= uc && uc <= 'z';
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}
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/**
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* Returns true iff |aChar| matches [A-Z].
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*
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* This function is basically what you thought isupper was, except its behavior
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* doesn't depend on the user's current locale.
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*/
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template<typename Char>
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constexpr bool
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IsAsciiUppercaseAlpha(Char aChar)
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{
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using UnsignedChar = typename detail::MakeUnsignedChar<Char>::Type;
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auto uc = static_cast<UnsignedChar>(aChar);
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return 'A' <= uc && uc <= 'Z';
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}
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/**
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* Returns true iff |aChar| matches [a-zA-Z].
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*
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* This function is basically what you thought isalpha was, except its behavior
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* doesn't depend on the user's current locale.
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*/
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template<typename Char>
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constexpr bool
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IsAsciiAlpha(Char aChar)
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{
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return IsAsciiLowercaseAlpha(aChar) || IsAsciiUppercaseAlpha(aChar);
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}
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/**
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* Returns true iff |aChar| matches [0-9].
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*
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* This function is basically what you thought isdigit was, except its behavior
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* doesn't depend on the user's current locale.
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*/
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template<typename Char>
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constexpr bool
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IsAsciiDigit(Char aChar)
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{
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using UnsignedChar = typename detail::MakeUnsignedChar<Char>::Type;
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auto uc = static_cast<UnsignedChar>(aChar);
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return '0' <= uc && uc <= '9';
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}
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/**
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* Returns true iff |aChar| matches [a-zA-Z0-9].
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*
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* This function is basically what you thought isalnum was, except its behavior
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* doesn't depend on the user's current locale.
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*/
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template<typename Char>
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constexpr bool
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IsAsciiAlphanumeric(Char aChar)
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{
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return IsAsciiDigit(aChar) || IsAsciiAlpha(aChar);
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}
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/**
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* Converts an ASCII alphanumeric digit [0-9a-zA-Z] to number as if in base-36.
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* (This function therefore works for decimal, hexadecimal, etc.).
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*/
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template<typename Char>
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uint8_t
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AsciiAlphanumericToNumber(Char aChar)
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{
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using UnsignedChar = typename detail::MakeUnsignedChar<Char>::Type;
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auto uc = static_cast<UnsignedChar>(aChar);
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if ('0' <= uc && uc <= '9') {
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return uc - '0';
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}
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if ('A' <= uc && uc <= 'Z') {
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return uc - 'A' + 10;
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}
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// Ideally this function would be constexpr, but unfortunately gcc at least as
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// of 6.4 forbids non-constexpr function calls in unevaluated constexpr
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// function calls. See bug 1453456. So for now, just assert and leave the
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// entire function non-constexpr.
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MOZ_ASSERT('a' <= uc && uc <= 'z',
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"non-ASCII alphanumeric character can't be converted to number");
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return uc - 'a' + 10;
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}
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} // namespace mozilla
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#endif /* mozilla_TextUtils_h */
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