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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<!--Weave of 'Nests' generated by Inweb-->
<div class="breadcrumbs">
<ul class="crumbs"><li><a href="../index.html">Home</a></li><li><a href="../inbuildn.html">Inbuild Modules</a></li><li><a href="index.html">supervisor</a></li><li><a href="index.html#2">Chapter 2: Conceptual Framework</a></li><li><b>Nests</b></li></ul></div>
<p class="purpose">Nests are repositories of Inform-related resources.</p>
<ul class="toc"><li><a href="2-nst.html#SP1">&#167;1. Creation</a></li><li><a href="2-nst.html#SP4">&#167;4. Search list</a></li><li><a href="2-nst.html#SP5">&#167;5. Search results</a></li></ul><hr class="tocbar">
<p class="commentary firstcommentary"><a id="SP1" class="paragraph-anchor"></a><b>&#167;1. Creation. </b>To "create" a nest here does not mean actually altering the file system, for
example by making a directory: nests here are merely notes in memory of
positions in the file system hierarchy which may or may not exist.
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">typedef</span><span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="reserved-syntax">inbuild_nest</span><span class="plain-syntax"> {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="identifier-syntax">pathname</span><span class="plain-syntax"> *</span><span class="identifier-syntax">location</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">read_only</span><span class="plain-syntax">; </span><span class="comment-syntax"> files cannot be written into this nest</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">tag_value</span><span class="plain-syntax">; </span><span class="comment-syntax"> used to indicate whether internal, external, and such</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">CLASS_DEFINITION</span>
<span class="plain-syntax">} </span><span class="reserved-syntax">inbuild_nest</span><span class="plain-syntax">;</span>
<span class="reserved-syntax">inbuild_nest</span><span class="plain-syntax"> *</span><span class="function-syntax">Nests::new</span><button class="popup" onclick="togglePopup('usagePopup1')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup1">Usage of <span class="code-font"><span class="function-syntax">Nests::new</span></span>:<br/>Inbuild Control - <a href="1-ic.html#SP12">&#167;12</a><br/>Registries - <a href="2-rgs.html#SP2">&#167;2</a></span></button><span class="plain-syntax">(</span><span class="identifier-syntax">pathname</span><span class="plain-syntax"> *</span><span class="identifier-syntax">P</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">inbuild_nest</span><span class="plain-syntax"> *</span><span class="identifier-syntax">N</span><span class="plain-syntax"> = </span><span class="identifier-syntax">CREATE</span><span class="plain-syntax">(</span><span class="reserved-syntax">inbuild_nest</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">N</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">location</span><span class="plain-syntax"> = </span><span class="identifier-syntax">P</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">N</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">read_only</span><span class="plain-syntax"> = </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">N</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">tag_value</span><span class="plain-syntax"> = -1;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">N</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
</pre>
<ul class="endnotetexts"><li>The structure inbuild_nest is accessed in 1/ic, 2/rgs, 3/bg, 3/is2, 4/em, 4/ebm, 4/km, 4/lm, 4/pm, 4/tm, 5/ps2 and here.</li></ul>
<p class="commentary firstcommentary"><a id="SP2" class="paragraph-anchor"></a><b>&#167;2. </b>Nests used by the Inform and Inbuild tools are tagged with the following
constants. (There used to be quite a good joke here, but refactoring of the
code removed its premise. Literate programming is like that sometimes.)
</p>
<p class="commentary">The sequence of the following enumerated values is very significant &mdash;
see below for why. Lower-tag-numbered origins are better than later ones.
</p>
<pre class="definitions code-font"><span class="definition-keyword">enum</span> <span class="constant-syntax">MATERIALS_NEST_TAG</span><span class="plain-syntax"> </span><span class="identifier-syntax">from</span><span class="plain-syntax"> </span><span class="constant-syntax">1</span>
<span class="definition-keyword">enum</span> <span class="constant-syntax">EXTERNAL_NEST_TAG</span>
<span class="definition-keyword">enum</span> <span class="constant-syntax">GENERIC_NEST_TAG</span>
<span class="definition-keyword">enum</span> <span class="constant-syntax">INTERNAL_NEST_TAG</span>
</pre>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="function-syntax">Nests::get_tag</span><button class="popup" onclick="togglePopup('usagePopup2')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup2">Usage of <span class="code-font"><span class="function-syntax">Nests::get_tag</span></span>:<br/><a href="2-nst.html#SP9">&#167;9</a><br/>Inbuild Control - <a href="1-ic.html#SP13">&#167;13</a><br/>Inform7 Skill - <a href="3-is2.html#SP1">&#167;1</a><br/>Inclusions - <a href="6-inc.html#SP6_1">&#167;6.1</a><br/>Census - <a href="7-cns.html#SP3">&#167;3</a>, <a href="7-cns.html#SP5">&#167;5</a>, <a href="7-cns.html#SP7_1">&#167;7.1</a><br/>Index Pages - <a href="7-ip.html#SP1_1_1_1">&#167;1.1.1.1</a>, <a href="7-ip.html#SP1_1_2_1_6_4_3">&#167;1.1.2.1.6.4.3</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">inbuild_nest</span><span class="plain-syntax"> *</span><span class="identifier-syntax">N</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">N</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) </span><span class="reserved-syntax">return</span><span class="plain-syntax"> -1;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">N</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">tag_value</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Nests::set_tag</span><button class="popup" onclick="togglePopup('usagePopup3')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup3">Usage of <span class="code-font"><span class="function-syntax">Nests::set_tag</span></span>:<br/>Inbuild Control - <a href="1-ic.html#SP12">&#167;12</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">inbuild_nest</span><span class="plain-syntax"> *</span><span class="identifier-syntax">N</span><span class="plain-syntax">, </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">t</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">N</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) </span><span class="identifier-syntax">internal_error</span><span class="plain-syntax">(</span><span class="string-syntax">"no nest"</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">N</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">tag_value</span><span class="plain-syntax"> = </span><span class="identifier-syntax">t</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP3" class="paragraph-anchor"></a><b>&#167;3. </b></p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Nests::protect</span><button class="popup" onclick="togglePopup('usagePopup4')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup4">Usage of <span class="code-font"><span class="function-syntax">Nests::protect</span></span>:<br/>Inbuild Control - <a href="1-ic.html#SP12">&#167;12</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">inbuild_nest</span><span class="plain-syntax"> *</span><span class="identifier-syntax">N</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">N</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">read_only</span><span class="plain-syntax"> = </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
<span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="function-syntax">Nests::is_protected</span><button class="popup" onclick="togglePopup('usagePopup5')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup5">Usage of <span class="code-font"><span class="function-syntax">Nests::is_protected</span></span>:<br/>Kit Services - <a href="5-ks.html#SP13_1">&#167;13.1</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">inbuild_nest</span><span class="plain-syntax"> *</span><span class="identifier-syntax">N</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">N</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">N</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">read_only</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP4" class="paragraph-anchor"></a><b>&#167;4. Search list. </b>When we search for copies, we do so by looking through nests in a list. The
following builds such lists, removing duplicates &mdash; where duplicates are
shown up by having the same textual form of pathname. (This is not foolproof
by any means: Unix is replete with ways to describe the same directory, thanks
to simlinks, <span class="extract"><span class="extract-syntax">~</span></span> and so on. But in the circumstances arising inside Inbuild,
it will do. In any case, having duplicates would not actually matter: it
would just produce search results which were more copious than needed.)
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Nests::add_to_search_sequence</span><span class="plain-syntax">(</span><span class="identifier-syntax">linked_list</span><span class="plain-syntax"> *</span><span class="identifier-syntax">search_list</span><span class="plain-syntax">, </span><span class="reserved-syntax">inbuild_nest</span><span class="plain-syntax"> *</span><span class="identifier-syntax">N</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">TEMPORARY_TEXT</span><span class="plain-syntax">(</span><span class="identifier-syntax">NS</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE_TO</span><span class="plain-syntax">(</span><span class="identifier-syntax">NS</span><span class="plain-syntax">, </span><span class="string-syntax">"%p"</span><span class="plain-syntax">, </span><span class="identifier-syntax">N</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">location</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">already_here</span><span class="plain-syntax"> = </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">inbuild_nest</span><span class="plain-syntax"> *</span><span class="identifier-syntax">M</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">LOOP_OVER_LINKED_LIST</span><span class="plain-syntax">(</span><span class="identifier-syntax">M</span><span class="plain-syntax">, </span><span class="reserved-syntax">inbuild_nest</span><span class="plain-syntax">, </span><span class="identifier-syntax">search_list</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">TEMPORARY_TEXT</span><span class="plain-syntax">(</span><span class="identifier-syntax">MS</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE_TO</span><span class="plain-syntax">(</span><span class="identifier-syntax">NS</span><span class="plain-syntax">, </span><span class="string-syntax">"%p"</span><span class="plain-syntax">, </span><span class="identifier-syntax">M</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">location</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">Str::eq</span><span class="plain-syntax">(</span><span class="identifier-syntax">NS</span><span class="plain-syntax">, </span><span class="identifier-syntax">MS</span><span class="plain-syntax">)) </span><span class="identifier-syntax">already_here</span><span class="plain-syntax"> = </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">DISCARD_TEXT</span><span class="plain-syntax">(</span><span class="identifier-syntax">MS</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">DISCARD_TEXT</span><span class="plain-syntax">(</span><span class="identifier-syntax">NS</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">already_here</span><span class="plain-syntax">) </span><span class="reserved-syntax">return</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">ADD_TO_LINKED_LIST</span><span class="plain-syntax">(</span><span class="identifier-syntax">N</span><span class="plain-syntax">, </span><span class="reserved-syntax">inbuild_nest</span><span class="plain-syntax">, </span><span class="identifier-syntax">search_list</span><span class="plain-syntax">);</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP5" class="paragraph-anchor"></a><b>&#167;5. Search results. </b>When we search a list of nests for copies satisfying certain requirements,
we create one of these for each hit:
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">typedef</span><span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="reserved-syntax">inbuild_search_result</span><span class="plain-syntax"> {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="reserved-syntax">inbuild_copy</span><span class="plain-syntax"> *</span><span class="identifier-syntax">copy</span><span class="plain-syntax">; </span><span class="comment-syntax"> what was found</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="reserved-syntax">inbuild_nest</span><span class="plain-syntax"> *</span><span class="identifier-syntax">nest</span><span class="plain-syntax">; </span><span class="comment-syntax"> from whence it came</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">CLASS_DEFINITION</span>
<span class="plain-syntax">} </span><span class="reserved-syntax">inbuild_search_result</span><span class="plain-syntax">;</span>
</pre>
<ul class="endnotetexts"><li>The structure inbuild_search_result is accessed in 2/ce, 2/rgs, 3/is, 5/ks, 5/ls, 6/inc, 7/dct, 7/cns, 7/ip, 7/ip2 and here.</li></ul>
<p class="commentary firstcommentary"><a id="SP6" class="paragraph-anchor"></a><b>&#167;6. </b>These can be created only as entries in a list:
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Nests::add_search_result</span><button class="popup" onclick="togglePopup('usagePopup6')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup6">Usage of <span class="code-font"><span class="function-syntax">Nests::add_search_result</span></span>:<br/>Extension Manager - <a href="4-em.html#SP6">&#167;6</a><br/>Extension Bundle Manager - <a href="4-ebm.html#SP6">&#167;6</a><br/>Kit Manager - <a href="4-km.html#SP7">&#167;7</a><br/>Language Manager - <a href="4-lm.html#SP5">&#167;5</a><br/>Pipeline Manager - <a href="4-pm.html#SP5">&#167;5</a><br/>Template Manager - <a href="4-tm.html#SP5">&#167;5</a></span></button><span class="plain-syntax">(</span><span class="identifier-syntax">linked_list</span><span class="plain-syntax"> *</span><span class="identifier-syntax">results</span><span class="plain-syntax">, </span><span class="reserved-syntax">inbuild_nest</span><span class="plain-syntax"> *</span><span class="identifier-syntax">N</span><span class="plain-syntax">, </span><span class="reserved-syntax">inbuild_copy</span><span class="plain-syntax"> *</span><span class="identifier-syntax">C</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">inbuild_requirement</span><span class="plain-syntax"> *</span><span class="identifier-syntax">req</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">inbuild_search_result</span><span class="plain-syntax"> *</span><span class="identifier-syntax">R</span><span class="plain-syntax"> = </span><span class="identifier-syntax">CREATE</span><span class="plain-syntax">(</span><span class="reserved-syntax">inbuild_search_result</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">R</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">nest</span><span class="plain-syntax"> = </span><span class="identifier-syntax">N</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">R</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">copy</span><span class="plain-syntax"> = </span><span class="identifier-syntax">C</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">C</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">found_by</span><span class="plain-syntax"> = </span><span class="identifier-syntax">req</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">req</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) </span><span class="identifier-syntax">internal_error</span><span class="plain-syntax">(</span><span class="string-syntax">"bad search result"</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">ADD_TO_LINKED_LIST</span><span class="plain-syntax">(</span><span class="identifier-syntax">R</span><span class="plain-syntax">, </span><span class="reserved-syntax">inbuild_search_result</span><span class="plain-syntax">, </span><span class="identifier-syntax">results</span><span class="plain-syntax">);</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP7" class="paragraph-anchor"></a><b>&#167;7. </b>And here is our search engine, such as it is. For each nest, we ask each
genre's manager to look for copies of that genre:
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Nests::search_for</span><button class="popup" onclick="togglePopup('usagePopup7')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup7">Usage of <span class="code-font"><span class="function-syntax">Nests::search_for</span></span>:<br/><a href="2-nst.html#SP8">&#167;8</a><br/>Language Services - <a href="5-ls.html#SP10">&#167;10</a><br/>Inclusions - <a href="6-inc.html#SP6_1_2">&#167;6.1.2</a><br/>Census - <a href="7-cns.html#SP7">&#167;7</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">inbuild_requirement</span><span class="plain-syntax"> *</span><span class="identifier-syntax">req</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">linked_list</span><span class="plain-syntax"> *</span><span class="identifier-syntax">search_list</span><span class="plain-syntax">, </span><span class="identifier-syntax">linked_list</span><span class="plain-syntax"> *</span><span class="identifier-syntax">results</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">inbuild_nest</span><span class="plain-syntax"> *</span><span class="identifier-syntax">N</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">LOOP_OVER_LINKED_LIST</span><span class="plain-syntax">(</span><span class="identifier-syntax">N</span><span class="plain-syntax">, </span><span class="reserved-syntax">inbuild_nest</span><span class="plain-syntax">, </span><span class="identifier-syntax">search_list</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">inbuild_genre</span><span class="plain-syntax"> *</span><span class="identifier-syntax">G</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">LOOP_OVER</span><span class="plain-syntax">(</span><span class="identifier-syntax">G</span><span class="plain-syntax">, </span><span class="reserved-syntax">inbuild_genre</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">VOID_METHOD_CALL</span><span class="plain-syntax">(</span><span class="identifier-syntax">G</span><span class="plain-syntax">, </span><span class="constant-syntax">GENRE_SEARCH_NEST_FOR_MTID</span><span class="plain-syntax">, </span><span class="identifier-syntax">N</span><span class="plain-syntax">, </span><span class="identifier-syntax">req</span><span class="plain-syntax">, </span><span class="identifier-syntax">results</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP8" class="paragraph-anchor"></a><b>&#167;8. </b>Oftentimes, we want only the single best result, and won't even look at the
others:
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">inbuild_search_result</span><span class="plain-syntax"> *</span><span class="function-syntax">Nests::search_for_best</span><button class="popup" onclick="togglePopup('usagePopup8')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup8">Usage of <span class="code-font"><span class="function-syntax">Nests::search_for_best</span></span>:<br/>Inter Skill - <a href="3-is.html#SP3">&#167;3</a>, <a href="3-is.html#SP4">&#167;4</a><br/>Kit Services - <a href="5-ks.html#SP7">&#167;7</a><br/>Language Services - <a href="5-ls.html#SP9">&#167;9</a><br/>Inclusions - <a href="6-inc.html#SP6_1">&#167;6.1</a><br/>Dictionary - <a href="7-dct.html#SP9">&#167;9</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">inbuild_requirement</span><span class="plain-syntax"> *</span><span class="identifier-syntax">req</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">linked_list</span><span class="plain-syntax"> *</span><span class="identifier-syntax">search_list</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">linked_list</span><span class="plain-syntax"> *</span><span class="identifier-syntax">L</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NEW_LINKED_LIST</span><span class="plain-syntax">(</span><span class="reserved-syntax">inbuild_search_result</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><a href="2-nst.html#SP7" class="function-link"><span class="function-syntax">Nests::search_for</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">req</span><span class="plain-syntax">, </span><span class="identifier-syntax">search_list</span><span class="plain-syntax">, </span><span class="identifier-syntax">L</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">inbuild_search_result</span><span class="plain-syntax"> *</span><span class="identifier-syntax">best</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">, *</span><span class="identifier-syntax">search_result</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">LOOP_OVER_LINKED_LIST</span><span class="plain-syntax">(</span><span class="identifier-syntax">search_result</span><span class="plain-syntax">, </span><span class="reserved-syntax">inbuild_search_result</span><span class="plain-syntax">, </span><span class="identifier-syntax">L</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><a href="2-nst.html#SP9" class="function-link"><span class="function-syntax">Nests::better_result</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">search_result</span><span class="plain-syntax">, </span><span class="identifier-syntax">best</span><span class="plain-syntax">))</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">best</span><span class="plain-syntax"> = </span><span class="identifier-syntax">search_result</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">best</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP9" class="paragraph-anchor"></a><b>&#167;9. </b>Where "better" is defined as follows. This innocent-looking function is
in fact critical to what Inbuild does. It uses tags on nests to prefer copies
in the Materials folder to those in the external nest, and to prefer those in
turn to copies in the internal nest; and within nests of equal importance,
it chooses the earliest hit among those which have the highest-precedence
semantic version numbers.
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="function-syntax">Nests::better_result</span><button class="popup" onclick="togglePopup('usagePopup9')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup9">Usage of <span class="code-font"><span class="function-syntax">Nests::better_result</span></span>:<br/><a href="2-nst.html#SP8">&#167;8</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">inbuild_search_result</span><span class="plain-syntax"> *</span><span class="identifier-syntax">R1</span><span class="plain-syntax">, </span><span class="reserved-syntax">inbuild_search_result</span><span class="plain-syntax"> *</span><span class="identifier-syntax">R2</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="comment-syntax"> Something is better than nothing</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">R1</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">R2</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="comment-syntax"> Otherwise, a more important nest beats a less important nest</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">o1</span><span class="plain-syntax"> = </span><a href="2-nst.html#SP2" class="function-link"><span class="function-syntax">Nests::get_tag</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">R1</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">nest</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">o2</span><span class="plain-syntax"> = </span><a href="2-nst.html#SP2" class="function-link"><span class="function-syntax">Nests::get_tag</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">R2</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">nest</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">o1</span><span class="plain-syntax"> &lt; </span><span class="identifier-syntax">o2</span><span class="plain-syntax">) </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">o1</span><span class="plain-syntax"> &gt; </span><span class="identifier-syntax">o2</span><span class="plain-syntax">) </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="comment-syntax"> Otherwise, a higher semantic version number beats a lower</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">VersionNumbers::gt</span><span class="plain-syntax">(</span><span class="identifier-syntax">R1</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">copy</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">edition</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">version</span><span class="plain-syntax">, </span><span class="identifier-syntax">R2</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">copy</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">edition</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">version</span><span class="plain-syntax">))</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="comment-syntax"> Otherwise, better the devil we know</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
</pre>
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