139 lines
4.2 KiB
C++
139 lines
4.2 KiB
C++
/*
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* Copyright (c) Meta Platforms, Inc. and affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*/
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#pragma once
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#include <algorithm>
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#include <bitset>
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#include <memory>
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#include <type_traits>
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#include <vector>
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#include <react/debug/react_native_assert.h>
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#include <react/renderer/css/CSSProperties.h>
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#include <react/renderer/css/CSSValueParser.h>
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namespace facebook::react {
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namespace detail {
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constexpr CSSProp kFirstCSSProp = static_cast<CSSProp>(0);
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template <CSSProp Prop = kFirstCSSProp>
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constexpr size_t maxSizeofDeclaredValue() {
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if constexpr (to_underlying(Prop) < kCSSPropCount - 1) {
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return std::max(
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sizeof(CSSDeclaredValue<Prop>),
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maxSizeofDeclaredValue<static_cast<CSSProp>(
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to_underlying(Prop) + 1)>());
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} else {
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return sizeof(CSSDeclaredValue<Prop>);
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}
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}
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} // namespace detail
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/**
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* CSSDeclaredStyle represents the set of style declarations on an element set
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* by the user. Users should generally not read from CSSDeclaredStyle directly,
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* and should instead use the computed style calculated on ShadowTree commit.
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*/
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class CSSDeclaredStyle {
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public:
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template <CSSProp Prop>
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void set(const CSSDeclaredValue<Prop>& value) {
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using DeclaredValueT = std::remove_cvref_t<CSSDeclaredValue<Prop>>;
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static_assert(sizeof(value) <= sizeof(PropMapping::value));
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static_assert(std::is_trivially_destructible_v<DeclaredValueT>);
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if (specifiedProperties_.test(to_underlying(Prop))) {
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auto it = std::lower_bound(
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properties_.begin(), properties_.end(), PropMapping{Prop, {}});
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react_native_assert(it->prop == Prop);
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std::construct_at(
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reinterpret_cast<DeclaredValueT*>(it->value.data()), value);
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} else {
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auto it = std::upper_bound(
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properties_.begin(), properties_.end(), PropMapping{Prop, {}});
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it = properties_.insert(it, {Prop, {}});
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std::construct_at(
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reinterpret_cast<DeclaredValueT*>(it->value.data()), value);
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specifiedProperties_.set(to_underlying(Prop));
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}
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}
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template <CSSProp Prop>
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bool set(std::string_view value) {
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auto cssProp = parseCSSProp<Prop>(value);
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set<Prop>(cssProp);
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return cssProp.hasValue();
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}
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bool set(std::string_view prop, std::string_view value) {
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return setPropIfHashMatches(fnv1a(prop), value);
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}
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/**
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* Returns the declared value, represented as the "unset" keyword if never
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* specified. Additional shorthands can be provided in order
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* of precedence if Prop is unset.
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*/
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template <CSSProp Prop, CSSProp... ShorthandsT>
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CSSDeclaredValue<Prop> get() const {
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if (specifiedProperties_.test(to_underlying(Prop))) {
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auto it = std::lower_bound(
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properties_.begin(), properties_.end(), PropMapping{Prop, {}});
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react_native_assert(it->prop == Prop);
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CSSDeclaredValue<Prop> value{*std::launder(
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reinterpret_cast<const CSSDeclaredValue<Prop>*>(it->value.data()))};
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if (value) {
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return value;
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}
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}
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if constexpr (sizeof...(ShorthandsT) == 0) {
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return {};
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} else {
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return get<ShorthandsT...>();
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}
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}
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bool operator==(const CSSDeclaredStyle& rhs) const = default;
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private:
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struct PropMapping {
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CSSProp prop;
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std::array<std::byte, detail::maxSizeofDeclaredValue()> value;
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constexpr bool operator<(const PropMapping& rhs) const {
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return to_underlying(prop) < to_underlying(rhs.prop);
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}
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};
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template <CSSProp CurrentProp = detail::kFirstCSSProp>
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constexpr bool setPropIfHashMatches(
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size_t propNameHash,
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std::string_view value) {
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constexpr std::string_view currentPropName =
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CSSPropDefinition<CurrentProp>::kName;
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constexpr size_t currentHash = fnv1a(currentPropName);
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if (currentHash == propNameHash) {
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return set<CurrentProp>(value);
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} else if constexpr (to_underlying(CurrentProp) < kCSSPropCount - 1) {
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return setPropIfHashMatches<static_cast<CSSProp>(
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to_underlying(CurrentProp) + 1)>(propNameHash, value);
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} else {
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return false;
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}
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}
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std::vector<PropMapping> properties_;
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std::bitset<kCSSPropCount> specifiedProperties_;
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};
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} // namespace facebook::react
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