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1 // Copyright 2015 The Chromium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 #ifndef COURGETTE_CONSECUTIVE_RANGE_VISITOR_H_ | |
6 #define COURGETTE_CONSECUTIVE_RANGE_VISITOR_H_ | |
7 | |
8 #include <iterator> | |
9 | |
10 #include "base/macros.h" | |
11 | |
12 namespace courgette { | |
13 | |
14 // Usage note: First check whether std::unique() would suffice. | |
15 // | |
16 // ConsecutiveRangeVisitor is a visitor to read equal consecutive items | |
17 // ("ranges") between two iterators. The base value of InputIterator must | |
18 // implement the == operator. | |
19 // | |
20 // Example: "AAAAABZZZZOO" consists of ranges ["AAAAA", "B", "ZZZZ", "OO"]. The | |
21 // visitor provides accessors to iterate through the ranges, and to access each | |
22 // range's value and repeat, i.e., [('A', 5), ('B', 1), ('Z', 4), ('O', 2)]. | |
23 template <class InputIterator> | |
24 class ConsecutiveRangeVisitor { | |
25 public: | |
26 ConsecutiveRangeVisitor(InputIterator begin, InputIterator end) | |
27 : head_(begin), end_(end) { | |
28 advance(); | |
29 } | |
30 | |
31 // Returns whether there are more ranges to traverse. | |
32 bool has_more() const { return tail_ != end_; } | |
33 | |
34 // Returns an iterator to an element in the current range. | |
35 InputIterator cur() const { return tail_; } | |
36 | |
37 // Returns the number of repeated elements in the current range. | |
38 size_t repeat() const { return std::distance(tail_, head_); } | |
39 | |
40 // Advances to the next range. | |
41 void advance() { | |
42 tail_ = head_; | |
43 if (head_ != end_) | |
44 while (++head_ != end_ && *head_ == *tail_) { | |
45 } | |
huangs
2015/12/04 21:27:15
Oh yeww, I'm moving brace back.
| |
46 } | |
47 | |
48 private: | |
49 InputIterator tail_; // The trailing pionter of a range (inclusive). | |
50 InputIterator head_; // The leading pointer of a range (exclusive). | |
51 InputIterator end_; // Store the end pointer so we know when to stop. | |
52 | |
53 DISALLOW_COPY_AND_ASSIGN(ConsecutiveRangeVisitor); | |
54 }; | |
55 | |
56 } // namespace courgette | |
57 | |
58 #endif // COURGETTE_CONSECUTIVE_RANGE_VISITOR_H_ | |
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