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- // Copyright 2015 The Chromium Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style license that can be
- // found in the LICENSE file.
- #ifndef COURGETTE_CONSECUTIVE_RANGE_VISITOR_H_
- #define COURGETTE_CONSECUTIVE_RANGE_VISITOR_H_
- #include <stddef.h>
- #include <iterator>
- namespace courgette {
- // Usage note: First check whether std::unique() would suffice.
- //
- // ConsecutiveRangeVisitor is a visitor to read equal consecutive items
- // ("ranges") between two iterators. The base value of InputIterator must
- // implement the == operator.
- //
- // Example: "AAAAABZZZZOO" consists of ranges ["AAAAA", "B", "ZZZZ", "OO"]. The
- // visitor provides accessors to iterate through the ranges, and to access each
- // range's value and repeat, i.e., [('A', 5), ('B', 1), ('Z', 4), ('O', 2)].
- template <class InputIterator>
- class ConsecutiveRangeVisitor {
- public:
- ConsecutiveRangeVisitor(InputIterator begin, InputIterator end)
- : head_(begin), end_(end) {
- advance();
- }
- ConsecutiveRangeVisitor(const ConsecutiveRangeVisitor&) = delete;
- ConsecutiveRangeVisitor& operator=(const ConsecutiveRangeVisitor&) = delete;
- // Returns whether there are more ranges to traverse.
- bool has_more() const { return tail_ != end_; }
- // Returns an iterator to an element in the current range.
- InputIterator cur() const { return tail_; }
- // Returns the number of repeated elements in the current range.
- size_t repeat() const { return std::distance(tail_, head_); }
- // Advances to the next range.
- void advance() {
- tail_ = head_;
- if (head_ != end_)
- while (++head_ != end_ && *head_ == *tail_) {}
- }
- private:
- InputIterator tail_; // The trailing pionter of a range (inclusive).
- InputIterator head_; // The leading pointer of a range (exclusive).
- InputIterator end_; // Store the end pointer so we know when to stop.
- };
- } // namespace courgette
- #endif // COURGETTE_CONSECUTIVE_RANGE_VISITOR_H_
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