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// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef COMPONENTS_FEED_CORE_V2_ALGORITHM_H_
#define COMPONENTS_FEED_CORE_V2_ALGORITHM_H_
namespace feed {
// Compares two sorted ranges. Iterates each range, calling |fn()| for all
// items. |fn()| takes the parameters (left_pointer, right_pointer). A null
// value is passed in for items not appearing in either the left or right range.
// For each call to |fn|, at least one parameter will be non-null.
template <typename ITER_A, typename ITER_B, typename VISITOR>
void DiffSortedRange(ITER_A left_begin,
ITER_A left_end,
ITER_B right_begin,
ITER_B right_end,
VISITOR fn) {
auto left = left_begin;
auto right = right_begin;
decltype(&*left) kLeftNull = nullptr;
decltype(&*right) kRightNull = nullptr;
for (;;) {
bool left_at_end = left == left_end, right_at_end = right == right_end;
if (left_at_end && right_at_end)
break;
if (!left_at_end && (right_at_end || *left < *right)) {
fn(&*left, kRightNull);
++left;
continue;
}
if (!right_at_end && (left_at_end || *right < *left)) {
fn(kLeftNull, &*right);
++right;
continue;
}
fn(&*left, &*right);
++left;
++right;
}
}
} // namespace feed
#endif // COMPONENTS_FEED_CORE_V2_ALGORITHM_H_
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