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 23// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 24// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 25// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 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