<ahref="lazy__mutable__copy_8h.html">Go to the documentation of this file.</a><divclass="fragment"><divclass="line"><aid="l00001"name="l00001"></a><spanclass="lineno"> 1</span><spanclass="comment">// Copyright 2010-2021 Google LLC</span></div>
<divclass="line"><aid="l00002"name="l00002"></a><spanclass="lineno"> 2</span><spanclass="comment">// Licensed under the Apache License, Version 2.0 (the "License");</span></div>
<divclass="line"><aid="l00003"name="l00003"></a><spanclass="lineno"> 3</span><spanclass="comment">// you may not use this file except in compliance with the License.</span></div>
<divclass="line"><aid="l00004"name="l00004"></a><spanclass="lineno"> 4</span><spanclass="comment">// You may obtain a copy of the License at</span></div>
<divclass="line"><aid="l00008"name="l00008"></a><spanclass="lineno"> 8</span><spanclass="comment">// Unless required by applicable law or agreed to in writing, software</span></div>
<divclass="line"><aid="l00009"name="l00009"></a><spanclass="lineno"> 9</span><spanclass="comment">// distributed under the License is distributed on an "AS IS" BASIS,</span></div>
<divclass="line"><aid="l00010"name="l00010"></a><spanclass="lineno"> 10</span><spanclass="comment">// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.</span></div>
<divclass="line"><aid="l00011"name="l00011"></a><spanclass="lineno"> 11</span><spanclass="comment">// See the License for the specific language governing permissions and</span></div>
<divclass="line"><aid="l00012"name="l00012"></a><spanclass="lineno"> 12</span><spanclass="comment">// limitations under the License.</span></div>
<divclass="line"><aid="l00023"name="l00023"></a><spanclass="lineno"> 23</span><spanclass="comment">// LazyMutableCopy<T> is a helper class for making an on-demand copy of an</span></div>
<divclass="line"><aid="l00024"name="l00024"></a><spanclass="lineno"> 24</span><spanclass="comment">// object of arbitrary type T. Type T must have a copy constructor.</span></div>
<divclass="line"><aid="l00032"name="l00032"></a><spanclass="lineno"> 32</span><spanclass="comment">// // Process "input" here without worrying about BAD_VALUE.</span></div>
<divclass="line"><aid="l00033"name="l00033"></a><spanclass="lineno"> 33</span><spanclass="comment">// A good pattern is to have function taking LazyMutableCopy<> as argument:</span></div>
<divclass="line"><aid="l00034"name="l00034"></a><spanclass="lineno"> 34</span><spanclass="comment">// void ProcessProto(LazyMutableCopy<Proto> input) { // pass by copy</span></div>
<divclass="line"><aid="l00037"name="l00037"></a><spanclass="lineno"> 37</span><spanclass="comment">// At the call site: ProcessProto({const_ref_to_my_proto});</span></div>
<divclass="line"><aid="l00039"name="l00039"></a><spanclass="lineno"> 39</span><spanclass="comment">// In basic usage, a LazyMutableCopy is in one of two states:</span></div>
<divclass="line"><aid="l00040"name="l00040"></a><spanclass="lineno"> 40</span><spanclass="comment">// - original: points to the const original. No memory allocated.</span></div>
<divclass="line"><aid="l00041"name="l00041"></a><spanclass="lineno"> 41</span><spanclass="comment">// - copy: points to a mutable copy of the original and owns it. Owning the</span></div>
<divclass="line"><aid="l00042"name="l00042"></a><spanclass="lineno"> 42</span><spanclass="comment">// copy means that the destructor will delete it, like std::unique_ptr<>.</span></div>
<divclass="line"><aid="l00043"name="l00043"></a><spanclass="lineno"> 43</span><spanclass="comment">// This is what you get by calling get_mutable().</span></div>
<divclass="line"><aid="l00047"name="l00047"></a><spanclass="lineno"> 47</span><spanclass="comment">// You always construct a LazyMutableCopy with a const reference to an object,</span></div>
<divclass="line"><aid="l00048"name="l00048"></a><spanclass="lineno"> 48</span><spanclass="comment">// which must outlive this class (unless get_mutable() was called).</span></div>
<divclass="line"><aid="l00052"name="l00052"></a><spanclass="lineno"> 52</span><spanclass="comment">// You can move a LazyMutableCopy, much like a std::unique_ptr<> or a const*.</span></div>
<divclass="line"><aid="l00053"name="l00053"></a><spanclass="lineno"> 53</span><spanclass="comment">// We simply rely on the default move constructors being available.</span></div>
<divclass="line"><aid="l00064"name="l00064"></a><spanclass="lineno"> 64</span><spanclass="comment">// True iff get_mutable() was called at least once (in which case the object</span></div>
<divclass="line"><aid="l00065"name="l00065"></a><spanclass="lineno"> 65</span><spanclass="comment">// was copied).</span></div>
<divclass="ttc"id="aclassoperations__research_1_1_lazy_mutable_copy_html_a5636913e03f5b56c1fb099c76f183e0b"><divclass="ttname"><ahref="classoperations__research_1_1_lazy_mutable_copy.html#a5636913e03f5b56c1fb099c76f183e0b">operations_research::LazyMutableCopy::LazyMutableCopy</a></div><divclass="ttdeci">LazyMutableCopy(const T &obj)</div><divclass="ttdef"><b>Definition:</b><ahref="lazy__mutable__copy_8h_source.html#l00049">lazy_mutable_copy.h:49</a></div></div>
<divclass="ttc"id="aclassoperations__research_1_1_lazy_mutable_copy_html_a9681b4de0a8572cf68ac6025484bfcef"><divclass="ttname"><ahref="classoperations__research_1_1_lazy_mutable_copy.html#a9681b4de0a8572cf68ac6025484bfcef">operations_research::LazyMutableCopy::get</a></div><divclass="ttdeci">const T & get() const</div><divclass="ttdef"><b>Definition:</b><ahref="lazy__mutable__copy_8h_source.html#l00055">lazy_mutable_copy.h:55</a></div></div>
<divclass="ttc"id="anamespaceoperations__research_html"><divclass="ttname"><ahref="namespaceoperations__research.html">operations_research</a></div><divclass="ttdoc">Collection of objects used to extend the Constraint Solver library.</div><divclass="ttdef"><b>Definition:</b><ahref="dense__doubly__linked__list_8h_source.html#l00021">dense_doubly_linked_list.h:21</a></div></div>
