1// Ceres Solver - A fast non-linear least squares minimizer
2// Copyright 2010, 2011, 2012 Google Inc. All rights reserved.
3// http://code.google.com/p/ceres-solver/
4//
5// Redistribution and use in source and binary forms, with or without
6// modification, are permitted provided that the following conditions are met:
7//
8// * Redistributions of source code must retain the above copyright notice,
9//   this list of conditions and the following disclaimer.
10// * Redistributions in binary form must reproduce the above copyright notice,
11//   this list of conditions and the following disclaimer in the documentation
12//   and/or other materials provided with the distribution.
13// * Neither the name of Google Inc. nor the names of its contributors may be
14//   used to endorse or promote products derived from this software without
15//   specific prior written permission.
16//
17// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
18// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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20// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
21// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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24// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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26// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
27// POSSIBILITY OF SUCH DAMAGE.
28//
29// Author: keir@google.com (Keir Mierle)
30
31#include "ceres/split.h"
32
33#include <string>
34#include <vector>
35#include <iterator>
36#include "ceres/internal/port.h"
37
38namespace ceres {
39
40// If we know how much to allocate for a vector of strings, we can allocate the
41// vector<string> only once and directly to the right size. This saves in
42// between 33-66 % of memory space needed for the result, and runs faster in the
43// microbenchmarks.
44//
45// The reserve is only implemented for the single character delim.
46//
47// The implementation for counting is cut-and-pasted from
48// SplitStringToIteratorUsing. I could have written my own counting iterator,
49// and use the existing template function, but probably this is more clear and
50// more sure to get optimized to reasonable code.
51static int CalculateReserveForVector(const string& full, const char* delim) {
52  int count = 0;
53  if (delim[0] != '\0' && delim[1] == '\0') {
54    // Optimize the common case where delim is a single character.
55    char c = delim[0];
56    const char* p = full.data();
57    const char* end = p + full.size();
58    while (p != end) {
59      if (*p == c) {  // This could be optimized with hasless(v,1) trick.
60        ++p;
61      } else {
62        while (++p != end && *p != c) {
63          // Skip to the next occurence of the delimiter.
64        }
65        ++count;
66      }
67    }
68  }
69  return count;
70}
71
72template <typename StringType, typename ITR>
73static inline
74void SplitStringToIteratorUsing(const StringType& full,
75                                const char* delim,
76                                ITR& result) {
77  // Optimize the common case where delim is a single character.
78  if (delim[0] != '\0' && delim[1] == '\0') {
79    char c = delim[0];
80    const char* p = full.data();
81    const char* end = p + full.size();
82    while (p != end) {
83      if (*p == c) {
84        ++p;
85      } else {
86        const char* start = p;
87        while (++p != end && *p != c) {
88          // Skip to the next occurence of the delimiter.
89        }
90        *result++ = StringType(start, p - start);
91      }
92    }
93    return;
94  }
95
96  string::size_type begin_index, end_index;
97  begin_index = full.find_first_not_of(delim);
98  while (begin_index != string::npos) {
99    end_index = full.find_first_of(delim, begin_index);
100    if (end_index == string::npos) {
101      *result++ = full.substr(begin_index);
102      return;
103    }
104    *result++ = full.substr(begin_index, (end_index - begin_index));
105    begin_index = full.find_first_not_of(delim, end_index);
106  }
107}
108
109void SplitStringUsing(const string& full,
110                      const char* delim,
111                      vector<string>* result) {
112  result->reserve(result->size() + CalculateReserveForVector(full, delim));
113  back_insert_iterator< vector<string> > it(*result);
114  SplitStringToIteratorUsing(full, delim, it);
115}
116
117}  // namespace ceres
118