a264f42bd6
This implements Maps.difference() helper function in C++. We need it to translate various Origin call-sites that use it. The implementation is written from scratch with Guava code used as reference to preserve semantics. Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
76 lines
2.5 KiB
C++
76 lines
2.5 KiB
C++
/*
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* Copyright (C) 2015 Cloudius Systems, Ltd.
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*/
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#pragma once
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#include <map>
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template<typename Tp>
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struct value_difference {
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Tp left_value;
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Tp right_value;
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value_difference(const Tp& left_value_, const Tp& right_value_)
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: left_value(left_value_)
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, right_value(right_value_)
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{ }
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};
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template<typename Key, typename Tp, typename Compare, typename Alloc>
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struct map_difference {
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// Entries in left map whose keys don't exist in the right map.
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std::map<Key, Tp, Compare> entries_only_on_left;
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// Entries in right map whose keys don't exist in the left map.
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std::map<Key, Tp, Compare> entries_only_on_right;
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// Entries that appear in both maps with the same value.
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std::map<Key, Tp, Compare> entries_in_common;
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// Entries that appear in both maps but have different values.
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std::map<Key, value_difference<Tp>, Compare> entries_differing;
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map_difference(const Compare& cmp, const Alloc& alloc)
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: entries_only_on_left{cmp, alloc}
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, entries_only_on_right{cmp, alloc}
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, entries_in_common{cmp, alloc}
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, entries_differing{cmp, alloc}
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{ }
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};
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template<typename Key, typename Tp, typename Compare, typename Alloc>
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inline
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map_difference<Key, Tp, Compare, Alloc>
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difference(const std::map<Key, Tp, Compare, Alloc>& left,
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const std::map<Key, Tp, Compare, Alloc>& right,
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const Compare& key_comp, const Alloc& alloc) {
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map_difference<Key, Tp, Compare, Alloc> diff{key_comp, alloc};
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diff.entries_only_on_right = right;
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for (auto&& kv : left) {
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auto&& left_key = kv.first;
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auto&& it = right.find(left_key);
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if (it != right.end()) {
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diff.entries_only_on_right.erase(left_key);
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auto&& left_value = kv.second;
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auto&& right_value = it->second;
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if (left_value == right_value) {
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diff.entries_in_common.emplace(kv);
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} else {
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value_difference<Tp> value_diff{left_value, right_value};
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diff.entries_differing.emplace(left_key, std::move(value_diff));
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}
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} else {
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diff.entries_only_on_left.emplace(kv);
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}
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}
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return diff;
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}
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template<typename Key, typename Tp, typename Compare, typename Alloc>
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inline
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map_difference<Key, Tp, Compare, Alloc>
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difference(const std::map<Key, Tp, Compare, Alloc>& left, const std::map<Key, Tp, Compare, Alloc>& right) {
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return difference(left, right, left.key_comp(), left.get_allocator());
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}
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