mirror of
https://github.com/facebook/react-native.git
synced 2025-11-01 09:14:26 +00:00
Valentin Shergin
11c9f480af
Summary: This diff makes the parsing *Props object with sub-props with duplicating names deterministic: only the first one will be assigned. Before this change, the order was not guaranteed because `qsort` sorting algorithm is not stable and because binary search that we use to search in the sorted array does not handle duplicates deterministically. The behavior when the only sub-prop (the first one) is being assigned actually desirable feature that exists on purpose. There are places where it's desired behavior (like TextInputProps) and in cases where it's not desired (we don't really have those), it's easy to "fix" implementing the custom constructor. Changelog: [Internal] Fabric-specific internal change. Reviewed By: JoshuaGross Differential Revision: D18607657 fbshipit-source-id: aa53a320e6a48877a0dd1b9351dfcc8a9f419b38
107 lines
2.9 KiB
C++
107 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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#include "RawPropsKeyMap.h"
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#include <algorithm>
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#include <cassert>
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#include <cstdlib>
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#include <cstring>
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namespace facebook {
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namespace react {
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bool RawPropsKeyMap::hasSameName(Item const &lhs, Item const &rhs) noexcept {
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return lhs.length == rhs.length &&
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(std::memcmp(lhs.name, rhs.name, lhs.length) == 0);
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}
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bool RawPropsKeyMap::shouldFirstOneBeBeforeSecondOne(
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Item const &lhs,
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Item const &rhs) noexcept {
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if (lhs.length != rhs.length) {
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return lhs.length < rhs.length;
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}
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return std::memcmp(lhs.name, rhs.name, rhs.length) < 0;
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}
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void RawPropsKeyMap::insert(
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RawPropsKey const &key,
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RawPropsValueIndex value) noexcept {
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auto item = Item{};
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item.value = value;
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key.render(item.name, &item.length);
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items_.push_back(item);
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}
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void RawPropsKeyMap::reindex() noexcept {
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// Sorting `items_` by property names length and then lexicographically.
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// Note, sort algorithm must be stable.
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std::stable_sort(
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items_.begin(),
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items_.end(),
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&RawPropsKeyMap::shouldFirstOneBeBeforeSecondOne);
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// Filtering out duplicating keys.
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// If some `*Props` object requests a prop more than once, only the first
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// request will be fulfilled. E.g. `TextInputProps` class has a sub-property
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// `backgroundColor` twice, the first time as part of `ViewProps` base-class
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// and the second as part of `BaseTextProps` base-class. In this
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// configuration, the only one which comes first (from `ViewProps`, which
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// appear first) will be assigned.
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items_.erase(
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std::unique(items_.begin(), items_.end(), &RawPropsKeyMap::hasSameName),
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items_.end());
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buckets_.resize(kPropNameLengthHardCap);
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auto length = RawPropsPropNameLength{0};
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for (auto i = 0; i < items_.size(); i++) {
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auto &item = items_[i];
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if (item.length != length) {
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for (auto j = length; j < item.length; j++) {
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buckets_[j] = i;
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}
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length = item.length;
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}
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}
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for (auto j = length; j < buckets_.size(); j++) {
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buckets_[j] = items_.size();
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}
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}
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RawPropsValueIndex RawPropsKeyMap::at(
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char const *name,
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RawPropsPropNameLength length) noexcept {
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assert(length > 0);
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assert(length < kPropNameLengthHardCap);
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// 1. Find the bucket.
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auto lower = int{buckets_[length - 1]};
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auto upper = int{buckets_[length]} - 1;
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assert(lower - 1 <= upper);
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// 2. Binary search in the bucket.
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while (lower <= upper) {
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auto median = (lower + upper) / 2;
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auto condition = std::memcmp(items_[median].name, name, length);
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if (condition < 0) {
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lower = median + 1;
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} else if (condition == 0) {
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return items_[median].value;
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} else /* if (condition > 0) */ {
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upper = median - 1;
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}
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}
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return kRawPropsValueIndexEmpty;
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}
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} // namespace react
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} // namespace facebook
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