| // Copyright 2015 The Chromium Authors |
| // 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_ |