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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 <iterator>
#include "base/macros.h"
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();
}
// 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.
DISALLOW_COPY_AND_ASSIGN(ConsecutiveRangeVisitor);
};
} // namespace courgette
#endif // COURGETTE_CONSECUTIVE_RANGE_VISITOR_H_