mirror of
https://github.com/facebook/react-native.git
synced 2025-11-01 09:14:26 +00:00
Samuel Susla
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
71 lines
2.0 KiB
C++
71 lines
2.0 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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#include "TextMeasureCache.h"
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#include <utility>
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namespace facebook {
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namespace react {
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static Rect rectFromDynamic(folly::dynamic const &data) {
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Point origin;
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origin.x = static_cast<Float>(data.getDefault("x", 0).getDouble());
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origin.y = static_cast<Float>(data.getDefault("y", 0).getDouble());
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Size size;
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size.width = static_cast<Float>(data.getDefault("width", 0).getDouble());
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size.height = static_cast<Float>(data.getDefault("height", 0).getDouble());
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Rect frame;
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frame.origin = origin;
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frame.size = size;
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return frame;
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}
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LineMeasurement::LineMeasurement(
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std::string text,
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Rect frame,
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Float descender,
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Float capHeight,
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Float ascender,
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Float xHeight)
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: text(std::move(text)),
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frame(frame),
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descender(descender),
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capHeight(capHeight),
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ascender(ascender),
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xHeight(xHeight) {}
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LineMeasurement::LineMeasurement(folly::dynamic const &data)
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: text(data.getDefault("text", "").getString()),
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frame(rectFromDynamic(data)),
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descender(
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static_cast<Float>(data.getDefault("descender", 0).getDouble())),
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capHeight(
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static_cast<Float>(data.getDefault("capHeight", 0).getDouble())),
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ascender(static_cast<Float>(data.getDefault("ascender", 0).getDouble())),
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xHeight(static_cast<Float>(data.getDefault("xHeight", 0).getDouble())) {}
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bool LineMeasurement::operator==(LineMeasurement const &rhs) const {
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return std::tie(
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this->text,
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this->frame,
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this->descender,
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this->capHeight,
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this->ascender,
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this->xHeight) ==
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std::tie(
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rhs.text,
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rhs.frame,
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rhs.descender,
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rhs.capHeight,
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rhs.ascender,
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rhs.xHeight);
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}
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} // namespace react
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} // namespace facebook
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