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
19 // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 // ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
21 // LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
22 // CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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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
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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
38 namespace 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.
CalculateReserveForVector(const string & full,const char * delim)51 static 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
72 template <typename StringType, typename ITR>
73 static inline
SplitStringToIteratorUsing(const StringType & full,const char * delim,ITR & result)74 void 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
SplitStringUsing(const string & full,const char * delim,vector<string> * result)109 void 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