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/*
Copyright (C) 2021 Apple Inc. All rights reserved.
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modification, are permitted provided that the following conditions
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notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND ANY
EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY
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(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include <wtf/text/StringView.h>
namespace WTF {
// SortedArrayMap is a map like HashMap, but it's read-only. It uses much less memory than HashMap.
// It uses binary search instead of hashing, so can be outperformed by HashMap for large maps.
// The array passed to the constructor has std::pair elements: keys first and values second.
// The array and the SortedArrayMap should typically both be global constant expressions.
class SortedArrayBase {
protected:
// Some informal empirical tests indicate that arrays shorter than this are faster to
// search with linear search than with binary search. Even if we don't get this threshold
// exactly right, it's helpful for both performance and code size to use linear search at
// least for very small arrays, and important for performance to make sure that we use
// binary search for much larger ones.
static constexpr size_t binarySearchThreshold = 20;
};
template<typename ArrayType> class SortedArrayMap : public SortedArrayBase {
public:
using ElementType = typename std::remove_extent_t<ArrayType>;
using ValueType = typename ElementType::second_type;
constexpr SortedArrayMap(const ArrayType&);
template<typename KeyArgument> bool contains(const KeyArgument&) const;
// FIXME: To match HashMap interface better, would be nice to get the default value from traits.
template<typename KeyArgument> ValueType get(const KeyArgument&, const ValueType& defaultValue = { }) const;
// FIXME: Should add a function like this to HashMap so the two kinds of maps are more interchangable.
template<typename KeyArgument> const ValueType* tryGet(const KeyArgument&) const;
private:
const ArrayType& m_array;
};
template<typename ArrayType> class SortedArraySet : public SortedArrayBase {
public:
constexpr SortedArraySet(const ArrayType&);
template<typename KeyArgument> bool contains(const KeyArgument&) const;
private:
const ArrayType& m_array;
};
struct ComparableStringView {
StringView string;
};
// NoUppercaseLettersOptimized means no characters with the 0x20 bit set.
// That means the strings can't include control characters, uppercase letters, or any of @[\]_.
enum class ASCIISubset : uint8_t { All, NoUppercaseLetters, NoUppercaseLettersOptimized };
template<ASCIISubset> struct ComparableASCIISubsetLiteral {
ASCIILiteral literal;
template<unsigned size> constexpr ComparableASCIISubsetLiteral(const char (&characters)[size]);
static std::optional<ComparableStringView> parse(StringView string) { return { { string } }; }
};
using ComparableASCIILiteral = ComparableASCIISubsetLiteral<ASCIISubset::All>;
using ComparableCaseFoldingASCIILiteral = ComparableASCIISubsetLiteral<ASCIISubset::NoUppercaseLetters>;
using ComparableLettersLiteral = ComparableASCIISubsetLiteral<ASCIISubset::NoUppercaseLettersOptimized>;
template<ASCIISubset subset> constexpr bool operator==(ComparableASCIISubsetLiteral<subset>, ComparableASCIISubsetLiteral<subset>);
template<ASCIISubset subset> constexpr bool operator<(ComparableASCIISubsetLiteral<subset>, ComparableASCIISubsetLiteral<subset>);
bool operator==(ComparableStringView, ComparableASCIILiteral);
bool operator==(ComparableStringView, ComparableCaseFoldingASCIILiteral);
bool operator==(ComparableStringView, ComparableLettersLiteral);
bool operator<(ComparableStringView, ComparableASCIILiteral);
bool operator<(ComparableStringView, ComparableCaseFoldingASCIILiteral);
bool operator<(ComparableStringView, ComparableLettersLiteral);
bool operator<(ComparableASCIILiteral, ComparableStringView);
bool operator<(ComparableCaseFoldingASCIILiteral, ComparableStringView);
bool operator<(ComparableLettersLiteral, ComparableStringView);
template<typename OtherType> bool operator==(OtherType, ComparableStringView);
template<typename StorageInteger> class PackedASCIILowerCodes {
public:
static_assert(std::is_unsigned_v<StorageInteger>);
template<unsigned size> constexpr PackedASCIILowerCodes(const char (&characters)[size]);
static std::optional<PackedASCIILowerCodes> parse(StringView);
constexpr StorageInteger value() const { return m_value; }
private:
template<unsigned size> static constexpr StorageInteger pack(const char (&characters)[size]);
explicit constexpr PackedASCIILowerCodes(StorageInteger);
StorageInteger m_value { 0 };
};
template<typename StorageInteger> constexpr bool operator==(PackedASCIILowerCodes<StorageInteger>, PackedASCIILowerCodes<StorageInteger>);
template<typename StorageInteger> constexpr bool operator<(PackedASCIILowerCodes<StorageInteger>, PackedASCIILowerCodes<StorageInteger>);
template<ASCIISubset subset> constexpr bool isInSubset(char character)
{
if (!(character && isASCII(character)))
return false;
switch (subset) {
case ASCIISubset::All:
return true;
case ASCIISubset::NoUppercaseLetters:
return !isASCIIUpper(character);
case ASCIISubset::NoUppercaseLettersOptimized:
return character == toASCIILowerUnchecked(character);
}
}
template<ASCIISubset subset> template<unsigned size> constexpr ComparableASCIISubsetLiteral<subset>::ComparableASCIISubsetLiteral(const char (&characters)[size])
: literal { ASCIILiteral::fromLiteralUnsafe(characters) }
{
ASSERT_UNDER_CONSTEXPR_CONTEXT(allOfConstExpr(&characters[0], &characters[size - 1], [] (char character) {
return isInSubset<subset>(character);
}));
ASSERT_UNDER_CONSTEXPR_CONTEXT(!characters[size - 1]);
}
template<typename ArrayType> constexpr SortedArrayMap<ArrayType>::SortedArrayMap(const ArrayType& array)
: m_array { array }
{
ASSERT_UNDER_CONSTEXPR_CONTEXT(isSortedConstExpr(std::begin(array), std::end(array), [] (auto& a, auto b) {
return a.first < b.first;
}));
}
template<typename, typename = void> constexpr bool HasParseMember = false;
template<typename T> constexpr bool HasParseMember<T, std::void_t<decltype(std::declval<T>().parse)>> = true;
template<typename ArrayType> template<typename KeyArgument> inline auto SortedArrayMap<ArrayType>::tryGet(const KeyArgument& key) const -> const ValueType*
{
using KeyType = typename ElementType::first_type;
auto parsedKey = [&key] {
if constexpr (HasParseMember<KeyType>)
return KeyType::parse(key);
else
return std::make_optional(key);
}();
if (!parsedKey)
return nullptr;
decltype(std::begin(m_array)) iterator;
if (std::size(m_array) < binarySearchThreshold) {
iterator = std::find_if(std::begin(m_array), std::end(m_array), [&parsedKey] (auto& pair) {
return pair.first == *parsedKey;
});
if (iterator == std::end(m_array))
return nullptr;
} else {
iterator = std::lower_bound(std::begin(m_array), std::end(m_array), *parsedKey, [] (auto& pair, auto& value) {
return pair.first < value;
});
if (iterator == std::end(m_array) || !(iterator->first == *parsedKey))
return nullptr;
}
return &iterator->second;
}
template<typename ArrayType> template<typename KeyArgument> inline auto SortedArrayMap<ArrayType>::get(const KeyArgument& key, const ValueType& defaultValue) const -> ValueType
{
auto result = tryGet(key);
return result ? *result : defaultValue;
}
template<typename ArrayType> template<typename KeyArgument> inline bool SortedArrayMap<ArrayType>::contains(const KeyArgument& key) const
{
return tryGet(key);
}
template<typename ArrayType> constexpr SortedArraySet<ArrayType>::SortedArraySet(const ArrayType& array)
: m_array { array }
{
ASSERT_UNDER_CONSTEXPR_CONTEXT(isSortedConstExpr(std::begin(array), std::end(array)));
}
template<typename ArrayType> template<typename KeyArgument> inline bool SortedArraySet<ArrayType>::contains(const KeyArgument& key) const
{
using KeyType = typename std::remove_extent_t<ArrayType>;
auto parsedKey = [&key] {
if constexpr (HasParseMember<KeyType>)
return KeyType::parse(key);
else
return std::make_optional(key);
}();
if (!parsedKey)
return false;
if (std::size(m_array) < binarySearchThreshold)
return std::find(std::begin(m_array), std::end(m_array), *parsedKey) != std::end(m_array);
auto iterator = std::lower_bound(std::begin(m_array), std::end(m_array), *parsedKey);
return iterator != std::end(m_array) && *iterator == *parsedKey;
}
constexpr int strcmpConstExpr(const char* a, const char* b)
{
while (*a == *b && *a && *b) {
++a;
++b;
}
return *a == *b ? 0 : *a < *b ? -1 : 1;
}
template<typename CharacterType> inline bool lessThanASCIICaseFolding(const CharacterType* characters, unsigned length, const char* literalWithNoUppercase)
{
for (unsigned i = 0; i < length; ++i) {
if (!literalWithNoUppercase[i])
return false;
if (auto character = toASCIILower(characters[i]); character != literalWithNoUppercase[i])
return character < literalWithNoUppercase[i];
}
return true;
}
inline bool lessThanASCIICaseFolding(StringView string, const char* literalWithNoUppercase)
{
if (string.is8Bit())
return lessThanASCIICaseFolding(string.characters8(), string.length(), literalWithNoUppercase);
return lessThanASCIICaseFolding(string.characters16(), string.length(), literalWithNoUppercase);
}
template<typename CharacterType> inline bool lessThanASCIICaseFolding(const char* literalWithNoUppercase, const CharacterType* characters, unsigned length)
{
for (unsigned i = 0; i < length; ++i) {
if (!literalWithNoUppercase[i])
return true;
if (auto character = toASCIILower(characters[i]); character != literalWithNoUppercase[i])
return literalWithNoUppercase[i] < character;
}
return false;
}
inline bool lessThanASCIICaseFolding(const char* literalWithNoUppercase, StringView string)
{
if (string.is8Bit())
return lessThanASCIICaseFolding(literalWithNoUppercase, string.characters8(), string.length());
return lessThanASCIICaseFolding(literalWithNoUppercase, string.characters16(), string.length());
}
template<ASCIISubset subset> constexpr bool operator==(ComparableASCIISubsetLiteral<subset> a, ComparableASCIISubsetLiteral<subset> b)
{
return !strcmpConstExpr(a.literal.characters(), b.literal.characters());
}
template<ASCIISubset subset> constexpr bool operator<(ComparableASCIISubsetLiteral<subset> a, ComparableASCIISubsetLiteral<subset> b)
{
return strcmpConstExpr(a.literal.characters(), b.literal.characters()) < 0;
}
inline bool operator==(ComparableStringView a, ComparableASCIILiteral b)
{
return a.string == b.literal;
}
inline bool operator<(ComparableStringView a, ComparableASCIILiteral b)
{
return codePointCompare(a.string, b.literal) < 0;
}
inline bool operator<(ComparableASCIILiteral a, ComparableStringView b)
{
return codePointCompare(a.literal, b.string) < 0;
}
inline bool operator==(ComparableStringView a, ComparableLettersLiteral b)
{
return equalLettersIgnoringASCIICaseCommon(a.string, b.literal);
}
inline bool operator<(ComparableStringView a, ComparableLettersLiteral b)
{
return lessThanASCIICaseFolding(a.string, b.literal);
}
inline bool operator<(ComparableLettersLiteral a, ComparableStringView b)
{
return lessThanASCIICaseFolding(a.literal, b.string);
}
inline bool operator==(ComparableStringView a, ComparableCaseFoldingASCIILiteral b)
{
return equalIgnoringASCIICase(a.string, b.literal);
}
inline bool operator<(ComparableStringView a, ComparableCaseFoldingASCIILiteral b)
{
return lessThanASCIICaseFolding(a.string, b.literal);
}
inline bool operator<(ComparableCaseFoldingASCIILiteral a, ComparableStringView b)
{
return lessThanASCIICaseFolding(a.literal, b.string);
}
template<typename OtherType> inline bool operator==(OtherType a, ComparableStringView b)
{
return b == a;
}
template<typename StorageInteger> template<unsigned size> constexpr PackedASCIILowerCodes<StorageInteger>::PackedASCIILowerCodes(const char (&string)[size])
: m_value { pack(string) }
{
}
template<typename StorageInteger> constexpr PackedASCIILowerCodes<StorageInteger>::PackedASCIILowerCodes(StorageInteger value)
: m_value { value }
{
}
template<typename StorageInteger> template<unsigned size> constexpr StorageInteger PackedASCIILowerCodes<StorageInteger>::pack(const char (&string)[size])
{
ASSERT_UNDER_CONSTEXPR_CONTEXT(size);
constexpr unsigned length = size - 1;
ASSERT_UNDER_CONSTEXPR_CONTEXT(!string[length]);
ASSERT_UNDER_CONSTEXPR_CONTEXT(length <= sizeof(StorageInteger));
StorageInteger result = 0;
for (unsigned index = 0; index < length; ++index) {
StorageInteger code = static_cast<uint8_t>(string[index]);
result |= code << ((sizeof(StorageInteger) - index - 1) * 8);
}
return result;
}
template<typename StorageInteger> auto PackedASCIILowerCodes<StorageInteger>::parse(StringView string) -> std::optional<PackedASCIILowerCodes>
{
if (string.length() > sizeof(StorageInteger))
return std::nullopt;
StorageInteger result = 0;
for (unsigned index = 0; index < string.length(); ++index) {
UChar code = string[index];
if (!isASCII(code))
return std::nullopt;
result |= static_cast<StorageInteger>(toASCIILower(code)) << ((sizeof(StorageInteger) - index - 1) * 8);
}
return PackedASCIILowerCodes(result);
}
template<typename StorageInteger> constexpr bool operator==(PackedASCIILowerCodes<StorageInteger> a, PackedASCIILowerCodes<StorageInteger> b)
{
return a.value() == b.value();
}
template<typename StorageInteger> constexpr bool operator<(PackedASCIILowerCodes<StorageInteger> a, PackedASCIILowerCodes<StorageInteger> b)
{
return a.value() < b.value();
}
template<typename ValueType> constexpr std::optional<ValueType> makeOptionalFromPointer(const ValueType* pointer)
{
if (!pointer)
return std::nullopt;
return *pointer;
}
}
// FIXME: Rename the Comparable and Packed types for clarity and to align them better with each other.
using WTF::ASCIISubset;
using WTF::ComparableASCIILiteral;
using WTF::ComparableASCIISubsetLiteral;
using WTF::ComparableCaseFoldingASCIILiteral;
using WTF::ComparableLettersLiteral;
using WTF::PackedASCIILowerCodes;
using WTF::SortedArrayMap;
using WTF::SortedArraySet;
using WTF::makeOptionalFromPointer;