117 lines
4.6 KiB
C++
117 lines
4.6 KiB
C++
/*
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* Copyright (C) 2018-2021 Apple Inc. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
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* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
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* THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#pragma once
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#include <wtf/CheckedArithmetic.h>
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#include <wtf/text/StringView.h>
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namespace WTF {
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// The parseInteger function template allows leading and trailing spaces as defined by isASCIISpace, and, after the leading spaces, allows a single leading "+".
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// The parseIntegerAllowingTrailingJunk function template is like parseInteger, but allows any characters after the integer.
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// FIXME: Should we add a version that does not allow "+"?
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// FIXME: Should we add a version that allows other definitions of spaces, like isHTMLSpace or isHTTPSpace?
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// FIXME: Should we add a version that does not allow leading and trailing spaces?
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template<typename IntegralType> std::optional<IntegralType> parseInteger(StringView, uint8_t base = 10);
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template<typename IntegralType> std::optional<IntegralType> parseIntegerAllowingTrailingJunk(StringView, uint8_t base = 10);
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enum class TrailingJunkPolicy { Disallow, Allow };
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template<typename IntegralType, typename CharacterType> std::optional<IntegralType> parseInteger(const CharacterType* data, size_t length, uint8_t base, TrailingJunkPolicy policy)
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{
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if (!data)
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return std::nullopt;
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while (length && isASCIISpace(*data)) {
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--length;
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++data;
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}
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bool isNegative = false;
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if (std::is_signed_v<IntegralType> && length && *data == '-') {
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--length;
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++data;
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isNegative = true;
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} else if (length && *data == '+') {
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--length;
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++data;
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}
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auto isCharacterAllowedInBase = [] (auto character, auto base) {
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if (isASCIIDigit(character))
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return character - '0' < base;
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return toASCIILowerUnchecked(character) >= 'a' && toASCIILowerUnchecked(character) < 'a' + std::min(base - 10, 26);
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};
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if (!(length && isCharacterAllowedInBase(*data, base)))
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return std::nullopt;
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Checked<IntegralType, RecordOverflow> value;
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do {
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IntegralType digitValue = isASCIIDigit(*data) ? *data - '0' : toASCIILowerUnchecked(*data) - 'a' + 10;
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value *= static_cast<IntegralType>(base);
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if (isNegative)
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value -= digitValue;
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else
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value += digitValue;
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} while (--length && isCharacterAllowedInBase(*++data, base));
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if (UNLIKELY(value.hasOverflowed()))
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return std::nullopt;
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if (policy == TrailingJunkPolicy::Disallow) {
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while (length && isASCIISpace(*data)) {
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--length;
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++data;
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}
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if (length)
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return std::nullopt;
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}
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return value.value();
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}
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template<typename IntegralType> std::optional<IntegralType> parseInteger(StringView string, uint8_t base)
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{
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if (string.is8Bit())
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return parseInteger<IntegralType>(string.characters8(), string.length(), base, TrailingJunkPolicy::Disallow);
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return parseInteger<IntegralType>(string.characters16(), string.length(), base, TrailingJunkPolicy::Disallow);
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}
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template<typename IntegralType> std::optional<IntegralType> parseIntegerAllowingTrailingJunk(StringView string, uint8_t base)
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{
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if (string.is8Bit())
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return parseInteger<IntegralType>(string.characters8(), string.length(), base, TrailingJunkPolicy::Allow);
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return parseInteger<IntegralType>(string.characters16(), string.length(), base, TrailingJunkPolicy::Allow);
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}
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}
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using WTF::parseInteger;
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using WTF::parseIntegerAllowingTrailingJunk;
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