mirror of
https://github.com/facebook/react-native.git
synced 2025-11-01 09:14:26 +00:00
Samuel SuslaandFacebook GitHub Bot
5fa6c5a941
Summary: changelog: [internal] You can read more about this rule on https://clang.llvm.org/extra/clang-tidy/checks/modernize-pass-by-value.html # Isn't it wasteful to copy? Isn't reference more efficient? This rule of thumb is no longer true since C++11 with move semantics. Let's look at some examples. # Option one ``` class TextHolder { public: TextBox(std::string const &text) : text_(text) {} private: std::string text_; }; ``` By using reference here, we prevent the caller from using rvalue to and avoiding copy. Regardless of what the caller passes in, copy always happens. # Option two ``` class TextHolder { public: TextBox(std::string const &text) : text_(text) {} TextBox(std::string &&text) : text_(std::move(text)) {} private: std::string text_; }; ``` Here, we provide two constructors, one for const reference and one for rvalue reference. This gives the caller option to avoid copy. But now we have two constructors, which is not ideal. # Option three (what we do in this diff) ``` class TextHolder { public: TextBox(std::string text) : text_(std::move(text)) {} private: std::string text_; }; ``` Here, the caller has option to avoid copy and we only have single constructor. Reviewed By: fkgozali, JoshuaGross Differential Revision: D33276841 fbshipit-source-id: 619d5123d2e28937b22874650366629f24f20a63
95 lines
2.9 KiB
C++
95 lines
2.9 KiB
C++
/*
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* Copyright (c) Facebook, Inc. and its 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 <memory>
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#include <butter/map.h>
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#include <butter/mutex.h>
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#include <react/renderer/componentregistry/ComponentDescriptorProvider.h>
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#include <react/renderer/core/ComponentDescriptor.h>
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#include <react/utils/ContextContainer.h>
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namespace facebook {
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namespace react {
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class ComponentDescriptorProviderRegistry;
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class ComponentDescriptorRegistry;
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using SharedComponentDescriptorRegistry =
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std::shared_ptr<const ComponentDescriptorRegistry>;
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/*
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* Registry of particular `ComponentDescriptor`s.
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*/
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class ComponentDescriptorRegistry {
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public:
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using Shared = std::shared_ptr<const ComponentDescriptorRegistry>;
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/*
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* Creates an object with stored `ComponentDescriptorParameters` which will
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* be used later to create `ComponentDescriptor`s.
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*/
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ComponentDescriptorRegistry(
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ComponentDescriptorParameters parameters,
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ComponentDescriptorProviderRegistry const &providerRegistry,
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ContextContainer::Shared contextContainer);
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/*
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* This is broken. Please do not use.
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* If you requesting a ComponentDescriptor and unsure that it's there, you are
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* doing something wrong.
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*/
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ComponentDescriptor const *
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findComponentDescriptorByHandle_DO_NOT_USE_THIS_IS_BROKEN(
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ComponentHandle componentHandle) const;
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ComponentDescriptor const &at(std::string const &componentName) const;
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ComponentDescriptor const &at(ComponentHandle componentHandle) const;
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bool hasComponentDescriptorAt(ComponentHandle componentHandle) const;
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ShadowNode::Shared createNode(
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Tag tag,
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std::string const &viewName,
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SurfaceId surfaceId,
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folly::dynamic const &props,
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SharedEventTarget const &eventTarget) const;
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void setFallbackComponentDescriptor(SharedComponentDescriptor descriptor);
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ComponentDescriptor::Shared getFallbackComponentDescriptor() const;
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private:
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friend class ComponentDescriptorProviderRegistry;
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void registerComponentDescriptor(
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SharedComponentDescriptor componentDescriptor) const;
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/*
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* Creates a `ComponentDescriptor` using specified
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* `ComponentDescriptorProvider` and stored `ComponentDescriptorParameters`,
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* and then adds that to the registry.
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* To be used by `ComponentDescriptorProviderRegistry` only.
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* Thread safe.
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*/
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void add(ComponentDescriptorProvider componentDescriptorProvider) const;
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mutable butter::shared_mutex mutex_;
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mutable butter::map<ComponentHandle, SharedComponentDescriptor>
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_registryByHandle;
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mutable butter::map<std::string, SharedComponentDescriptor> _registryByName;
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ComponentDescriptor::Shared _fallbackComponentDescriptor;
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ComponentDescriptorParameters parameters_{};
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ComponentDescriptorProviderRegistry const &providerRegistry_;
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ContextContainer::Shared contextContainer_;
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};
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} // namespace react
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} // namespace facebook
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