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| <a href="lazy_8h.html">Go to the documentation of this file.</a><div class="fragment"><div class="line"><a id="l00001" name="l00001"></a><span class="lineno"> 1</span><span class="comment">/*</span></div> |
| <div class="line"><a id="l00002" name="l00002"></a><span class="lineno"> 2</span><span class="comment"> * Licensed to the Apache Software Foundation (ASF) under one</span></div> |
| <div class="line"><a id="l00003" name="l00003"></a><span class="lineno"> 3</span><span class="comment"> * or more contributor license agreements. See the NOTICE file</span></div> |
| <div class="line"><a id="l00004" name="l00004"></a><span class="lineno"> 4</span><span class="comment"> * distributed with this work for additional information</span></div> |
| <div class="line"><a id="l00005" name="l00005"></a><span class="lineno"> 5</span><span class="comment"> * regarding copyright ownership. The ASF licenses this file</span></div> |
| <div class="line"><a id="l00006" name="l00006"></a><span class="lineno"> 6</span><span class="comment"> * to you under the Apache License, Version 2.0 (the</span></div> |
| <div class="line"><a id="l00007" name="l00007"></a><span class="lineno"> 7</span><span class="comment"> * "License"); you may not use this file except in compliance</span></div> |
| <div class="line"><a id="l00008" name="l00008"></a><span class="lineno"> 8</span><span class="comment"> * with the License. You may obtain a copy of the License at</span></div> |
| <div class="line"><a id="l00009" name="l00009"></a><span class="lineno"> 9</span><span class="comment"> *</span></div> |
| <div class="line"><a id="l00010" name="l00010"></a><span class="lineno"> 10</span><span class="comment"> * http://www.apache.org/licenses/LICENSE-2.0</span></div> |
| <div class="line"><a id="l00011" name="l00011"></a><span class="lineno"> 11</span><span class="comment"> *</span></div> |
| <div class="line"><a id="l00012" name="l00012"></a><span class="lineno"> 12</span><span class="comment"> * Unless required by applicable law or agreed to in writing,</span></div> |
| <div class="line"><a id="l00013" name="l00013"></a><span class="lineno"> 13</span><span class="comment"> * software distributed under the License is distributed on an</span></div> |
| <div class="line"><a id="l00014" name="l00014"></a><span class="lineno"> 14</span><span class="comment"> * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY</span></div> |
| <div class="line"><a id="l00015" name="l00015"></a><span class="lineno"> 15</span><span class="comment"> * KIND, either express or implied. See the License for the</span></div> |
| <div class="line"><a id="l00016" name="l00016"></a><span class="lineno"> 16</span><span class="comment"> * specific language governing permissions and limitations</span></div> |
| <div class="line"><a id="l00017" name="l00017"></a><span class="lineno"> 17</span><span class="comment"> * under the License.</span></div> |
| <div class="line"><a id="l00018" name="l00018"></a><span class="lineno"> 18</span><span class="comment"> */</span></div> |
| <div class="line"><a id="l00019" name="l00019"></a><span class="lineno"> 19</span> </div> |
| <div class="line"><a id="l00020" name="l00020"></a><span class="lineno"> 20</span><span class="preprocessor">#pragma once</span></div> |
| <div class="line"><a id="l00021" name="l00021"></a><span class="lineno"> 21</span> </div> |
| <div class="line"><a id="l00024" name="l00024"></a><span class="lineno"> 24</span> </div> |
| <div class="line"><a id="l00025" name="l00025"></a><span class="lineno"> 25</span><span class="preprocessor">#include <concepts></span></div> |
| <div class="line"><a id="l00026" name="l00026"></a><span class="lineno"> 26</span><span class="preprocessor">#include <functional></span></div> |
| <div class="line"><a id="l00027" name="l00027"></a><span class="lineno"> 27</span><span class="preprocessor">#include <mutex></span></div> |
| <div class="line"><a id="l00028" name="l00028"></a><span class="lineno"> 28</span> </div> |
| <div class="line"><a id="l00029" name="l00029"></a><span class="lineno"> 29</span><span class="preprocessor">#include "iceberg/result.h"</span></div> |
| <div class="line"><a id="l00030" name="l00030"></a><span class="lineno"> 30</span><span class="preprocessor">#include "iceberg/util/macros.h"</span></div> |
| <div class="line"><a id="l00031" name="l00031"></a><span class="lineno"> 31</span> </div> |
| <div class="line"><a id="l00032" name="l00032"></a><span class="lineno"> 32</span><span class="keyword">namespace </span>iceberg {</div> |
| <div class="line"><a id="l00033" name="l00033"></a><span class="lineno"> 33</span> </div> |
| <div class="line"><a id="l00034" name="l00034"></a><span class="lineno"> 34</span><span class="keyword">template</span> <auto InitFunc></div> |
| <div class="foldopen" id="foldopen00035" data-start="{" data-end="};"> |
| <div class="line"><a id="l00035" name="l00035"></a><span class="lineno"><a class="line" href="classiceberg_1_1Lazy.html"> 35</a></span><span class="keyword">class </span><a class="code hl_class" href="classiceberg_1_1Lazy.html">Lazy</a> {</div> |
| <div class="line"><a id="l00036" name="l00036"></a><span class="lineno"> 36</span> <span class="keyword">template</span> <<span class="keyword">typename</span> R></div> |
| <div class="line"><a id="l00037" name="l00037"></a><span class="lineno"> 37</span> <span class="keyword">struct </span>Trait;</div> |
| <div class="line"><a id="l00038" name="l00038"></a><span class="lineno"> 38</span> </div> |
| <div class="line"><a id="l00039" name="l00039"></a><span class="lineno"> 39</span> <span class="keyword">template</span> <<span class="keyword">typename</span> R, <span class="keyword">typename</span>... Args></div> |
| <div class="line"><a id="l00040" name="l00040"></a><span class="lineno"> 40</span> <span class="keyword">struct </span>Trait<R (*)(Args...)> {</div> |
| <div class="line"><a id="l00041" name="l00041"></a><span class="lineno"> 41</span> <span class="keyword">using </span>ReturnType = R::value_type;</div> |
| <div class="line"><a id="l00042" name="l00042"></a><span class="lineno"> 42</span> };</div> |
| <div class="line"><a id="l00043" name="l00043"></a><span class="lineno"> 43</span> </div> |
| <div class="line"><a id="l00044" name="l00044"></a><span class="lineno"> 44</span> <span class="keyword">using </span>T = Trait<<span class="keyword">decltype</span>(InitFunc)>::ReturnType;</div> |
| <div class="line"><a id="l00045" name="l00045"></a><span class="lineno"> 45</span> </div> |
| <div class="line"><a id="l00046" name="l00046"></a><span class="lineno"> 46</span> <span class="keyword">public</span>:</div> |
| <div class="line"><a id="l00047" name="l00047"></a><span class="lineno"> 47</span> <span class="keyword">template</span> <<span class="keyword">typename</span>... Args></div> |
| <div class="line"><a id="l00048" name="l00048"></a><span class="lineno"> 48</span> <span class="keyword">requires</span> std::invocable<<span class="keyword">decltype</span>(InitFunc), Args...> &&</div> |
| <div class="line"><a id="l00049" name="l00049"></a><span class="lineno"> 49</span> std::same_as<std::invoke_result_t<<span class="keyword">decltype</span>(InitFunc), Args...>, Result<T>></div> |
| <div class="line"><a id="l00050" name="l00050"></a><span class="lineno"> 50</span> Result<std::reference_wrapper<T>> Get(Args&&... args)<span class="keyword"> const </span>{</div> |
| <div class="line"><a id="l00051" name="l00051"></a><span class="lineno"> 51</span> Result<T> result;</div> |
| <div class="line"><a id="l00052" name="l00052"></a><span class="lineno"> 52</span> std::call_once(flag_, [&result, <span class="keyword">this</span>, &args...]() {</div> |
| <div class="line"><a id="l00053" name="l00053"></a><span class="lineno"> 53</span> result = InitFunc(std::forward<Args>(args)...);</div> |
| <div class="line"><a id="l00054" name="l00054"></a><span class="lineno"> 54</span> if (result) {</div> |
| <div class="line"><a id="l00055" name="l00055"></a><span class="lineno"> 55</span> this->value_ = std::move(result.value());</div> |
| <div class="line"><a id="l00056" name="l00056"></a><span class="lineno"> 56</span> }</div> |
| <div class="line"><a id="l00057" name="l00057"></a><span class="lineno"> 57</span> });</div> |
| <div class="line"><a id="l00058" name="l00058"></a><span class="lineno"> 58</span> ICEBERG_RETURN_UNEXPECTED(result);</div> |
| <div class="line"><a id="l00059" name="l00059"></a><span class="lineno"> 59</span> <span class="keywordflow">return</span> std::ref(value_);</div> |
| <div class="line"><a id="l00060" name="l00060"></a><span class="lineno"> 60</span> }</div> |
| <div class="line"><a id="l00061" name="l00061"></a><span class="lineno"> 61</span> </div> |
| <div class="line"><a id="l00062" name="l00062"></a><span class="lineno"> 62</span> <span class="keyword">private</span>:</div> |
| <div class="line"><a id="l00063" name="l00063"></a><span class="lineno"> 63</span> <span class="keyword">mutable</span> T value_;</div> |
| <div class="line"><a id="l00064" name="l00064"></a><span class="lineno"> 64</span> <span class="keyword">mutable</span> std::once_flag flag_;</div> |
| <div class="line"><a id="l00065" name="l00065"></a><span class="lineno"> 65</span>};</div> |
| </div> |
| <div class="line"><a id="l00066" name="l00066"></a><span class="lineno"> 66</span> </div> |
| <div class="line"><a id="l00067" name="l00067"></a><span class="lineno"> 67</span>}; <span class="comment">// namespace iceberg</span></div> |
| <div class="ttc" id="aclassiceberg_1_1Lazy_html"><div class="ttname"><a href="classiceberg_1_1Lazy.html">iceberg::Lazy</a></div><div class="ttdef"><b>Definition</b> lazy.h:35</div></div> |
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