124 lines
4.4 KiB
C++
124 lines
4.4 KiB
C++
// Ceres Solver - A fast non-linear least squares minimizer
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// Copyright 2015 Google Inc. All rights reserved.
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// http://ceres-solver.org/
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are met:
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//
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// * Redistributions of source code must retain the above copyright notice,
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// this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above copyright notice,
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// this list of conditions and the following disclaimer in the documentation
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// and/or other materials provided with the distribution.
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// * Neither the name of Google Inc. nor the names of its contributors may be
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// used to endorse or promote products derived from this software without
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// specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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// POSSIBILITY OF SUCH DAMAGE.
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//
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// Author: keir@google.com (Keir Mierle)
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#include "ceres/split.h"
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#include <iterator>
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#include <string>
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#include <vector>
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#include "ceres/internal/port.h"
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namespace ceres {
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namespace internal {
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using std::string;
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using std::vector;
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// If we know how much to allocate for a vector of strings, we can allocate the
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// vector<string> only once and directly to the right size. This saves in
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// between 33-66 % of memory space needed for the result, and runs faster in the
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// microbenchmarks.
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//
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// The reserve is only implemented for the single character delim.
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//
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// The implementation for counting is cut-and-pasted from
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// SplitStringToIteratorUsing. I could have written my own counting iterator,
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// and use the existing template function, but probably this is more clear and
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// more sure to get optimized to reasonable code.
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static int CalculateReserveForVector(const string& full, const char* delim) {
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int count = 0;
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if (delim[0] != '\0' && delim[1] == '\0') {
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// Optimize the common case where delim is a single character.
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char c = delim[0];
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const char* p = full.data();
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const char* end = p + full.size();
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while (p != end) {
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if (*p == c) { // This could be optimized with hasless(v,1) trick.
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++p;
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} else {
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while (++p != end && *p != c) {
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// Skip to the next occurence of the delimiter.
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}
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++count;
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}
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}
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}
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return count;
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}
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template <typename StringType, typename ITR>
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static inline
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void SplitStringToIteratorUsing(const StringType& full,
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const char* delim,
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ITR& result) {
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// Optimize the common case where delim is a single character.
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if (delim[0] != '\0' && delim[1] == '\0') {
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char c = delim[0];
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const char* p = full.data();
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const char* end = p + full.size();
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while (p != end) {
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if (*p == c) {
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++p;
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} else {
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const char* start = p;
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while (++p != end && *p != c) {
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// Skip to the next occurence of the delimiter.
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}
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*result++ = StringType(start, p - start);
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}
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}
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return;
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}
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string::size_type begin_index, end_index;
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begin_index = full.find_first_not_of(delim);
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while (begin_index != string::npos) {
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end_index = full.find_first_of(delim, begin_index);
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if (end_index == string::npos) {
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*result++ = full.substr(begin_index);
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return;
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}
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*result++ = full.substr(begin_index, (end_index - begin_index));
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begin_index = full.find_first_not_of(delim, end_index);
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}
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}
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void SplitStringUsing(const string& full,
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const char* delim,
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vector<string>* result) {
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result->reserve(result->size() + CalculateReserveForVector(full, delim));
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std::back_insert_iterator<vector<string> > it(*result);
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SplitStringToIteratorUsing(full, delim, it);
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}
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} // namespace internal
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} // namespace ceres
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