59 lines
1.9 KiB
C++
59 lines
1.9 KiB
C++
#pragma once
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#include <oxenc/bt_value.h>
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#include <cassert>
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#ifndef NDEBUG
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#include <algorithm>
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#endif
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namespace session::bt {
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using oxenc::bt_dict;
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using oxenc::bt_list;
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/// Merges two bt dicts together: the returned dict includes all keys in a or b. Keys in *both*
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/// dicts get their value from `a`, otherwise the value is that of the dict that contains the key.
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bt_dict merge(const bt_dict& a, const bt_dict& b);
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/// Merges two ordered bt_lists together using a predicate to determine order. The input lists must
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/// be sorted to begin with. `cmp` must be callable with a pair of `const bt_value&` arguments and
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/// must return true if the first argument should be considered less than the second argument. By
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/// default this skips elements from b that compare equal to a value of a, but you can include all
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/// the duplicates by specifying the `duplicates` parameter as true.
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template <typename Compare>
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bt_list merge_sorted(const bt_list& a, const bt_list& b, Compare cmp, bool duplicates = false) {
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bt_list result;
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auto it_a = a.begin();
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auto it_b = b.begin();
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assert(std::is_sorted(it_a, a.end(), cmp));
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assert(std::is_sorted(it_b, b.end(), cmp));
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if (duplicates) {
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while (it_a != a.end() && it_b != b.end()) {
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if (!cmp(*it_a, *it_b)) // *b <= *a
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result.push_back(*it_b++);
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else // *a < *b
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result.push_back(*it_a++);
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}
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} else {
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while (it_a != a.end() && it_b != b.end()) {
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if (cmp(*it_b, *it_a)) // *b < *a
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result.push_back(*it_b++);
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else if (cmp(*it_a, *it_b)) // *a < *b
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result.push_back(*it_a++);
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else // *a == *b
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++it_b; // skip it
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}
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}
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if (it_a != a.end())
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result.insert(result.end(), it_a, a.end());
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else if (it_b != b.end())
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result.insert(result.end(), it_b, b.end());
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return result;
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}
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} // namespace session::bt
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