328 lines
66 KiB
HTML
328 lines
66 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<head>
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<title>Trees</title>
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<h1><a href="../index.html">
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<img src="../docs-assets/Octagram.png" width=72 height=72">
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</a></h1>
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<ul><li><a href="../inweb/index.html">inweb</a></li>
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</ul><h2>Foundation Module</h2><ul>
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<li><a href="index.html"><span class="selectedlink">foundation</span></a></li>
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<li><a href="../foundation-test/index.html">foundation-test</a></li>
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</ul><h2>Example Webs</h2><ul>
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<li><a href="../goldbach/index.html">goldbach</a></li>
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<li><a href="../twinprimes/twinprimes.html">twinprimes</a></li>
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<li><a href="../eastertide/index.html">eastertide</a></li>
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</ul><h2>Repository</h2><ul>
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<li><a href="https://github.com/ganelson/inweb"><img src="../docs-assets/github.png" height=18> github</a></li>
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</ul><h2>Related Projects</h2><ul>
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<li><a href="../../../inform/docs/index.html">inform</a></li>
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<li><a href="../../../intest/docs/index.html">intest</a></li>
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<main role="main">
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<!--Weave of 'Trees' generated by Inweb-->
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<ul class="crumbs"><li><a href="../index.html">Home</a></li><li><a href="index.html">foundation</a></li><li><a href="index.html#2">Chapter 2: Memory, Streams and Collections</a></li><li><b>Trees</b></li></ul><p class="purpose">To provide heterogeneous tree structures, where a node can be any structure known to the Foundation memory manager.</p>
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<ul class="toc"><li><a href="2-trs.html#SP1">§1. Trees and nodes</a></li><li><a href="2-trs.html#SP6">§6. Types</a></li><li><a href="2-trs.html#SP10">§10. Hierarchy</a></li><li><a href="2-trs.html#SP13">§13. Traversals</a></li></ul><hr class="tocbar">
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<p class="commentary firstcommentary"><a id="SP1"></a><b>§1. Trees and nodes. </b>The tree itself is really just a root node, which is initially null, so that
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a tree can be empty.
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</p>
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<pre class="displayed-code all-displayed-code code-font">
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<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">heterogeneous_tree</span><span class="plain-syntax"> {</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="reserved-syntax">tree_type</span><span class="plain-syntax"> *</span><span class="identifier-syntax">type</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="reserved-syntax">tree_node</span><span class="plain-syntax"> *</span><span class="identifier-syntax">root</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="constant-syntax">MEMORY_MANAGEMENT</span>
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<span class="plain-syntax">} </span><span class="reserved-syntax">heterogeneous_tree</span><span class="plain-syntax">;</span>
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</pre>
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<ul class="endnotetexts"><li>The structure heterogeneous_tree is private to this section.</li></ul>
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<p class="commentary firstcommentary"><a id="SP2"></a><b>§2. </b></p>
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<pre class="displayed-code all-displayed-code code-font">
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<span class="reserved-syntax">heterogeneous_tree</span><span class="plain-syntax"> *</span><span class="function-syntax">Trees::new</span><span class="plain-syntax">(</span><span class="reserved-syntax">tree_type</span><span class="plain-syntax"> *</span><span class="identifier-syntax">type</span><span class="plain-syntax">) {</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">heterogeneous_tree</span><span class="plain-syntax"> *</span><span class="identifier-syntax">T</span><span class="plain-syntax"> = </span><span class="identifier-syntax">CREATE</span><span class="plain-syntax">(</span><span class="reserved-syntax">heterogeneous_tree</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">T</span><span class="plain-syntax">-></span><span class="element-syntax">type</span><span class="plain-syntax"> = </span><span class="identifier-syntax">type</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">T</span><span class="plain-syntax">-></span><span class="element-syntax">root</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">T</span><span class="plain-syntax">;</span>
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<span class="plain-syntax">}</span>
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</pre>
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<p class="commentary firstcommentary"><a id="SP3"></a><b>§3. </b></p>
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<pre class="displayed-code all-displayed-code code-font">
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<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">tree_node</span><span class="plain-syntax"> {</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="reserved-syntax">heterogeneous_tree</span><span class="plain-syntax"> *</span><span class="identifier-syntax">owner</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="reserved-syntax">tree_node_type</span><span class="plain-syntax"> *</span><span class="identifier-syntax">type</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="reserved-syntax">general_pointer</span><span class="plain-syntax"> </span><span class="identifier-syntax">content</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="reserved-syntax">tree_node</span><span class="plain-syntax"> *</span><span class="identifier-syntax">next</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="reserved-syntax">tree_node</span><span class="plain-syntax"> *</span><span class="identifier-syntax">parent</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="reserved-syntax">tree_node</span><span class="plain-syntax"> *</span><span class="identifier-syntax">child</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="constant-syntax">MEMORY_MANAGEMENT</span>
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<span class="plain-syntax">} </span><span class="reserved-syntax">tree_node</span><span class="plain-syntax">;</span>
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</pre>
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<ul class="endnotetexts"><li>The structure tree_node is accessed in 2/mmr, 4/taa and here.</li></ul>
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<p class="commentary firstcommentary"><a id="SP4"></a><b>§4. </b>A node is created in limbo, removed from its tree, but it is still somehow
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owned by it.
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</p>
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<pre class="displayed-code all-displayed-code code-font">
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<span class="reserved-syntax">tree_node</span><span class="plain-syntax"> *</span><span class="function-syntax">Trees::new_node</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">Trees::new_node</span></span>:<br/><a href="2-trs.html#SP5">§5</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">heterogeneous_tree</span><span class="plain-syntax"> *</span><span class="identifier-syntax">T</span><span class="plain-syntax">, </span><span class="reserved-syntax">tree_node_type</span><span class="plain-syntax"> *</span><span class="identifier-syntax">type</span><span class="plain-syntax">, </span><span class="reserved-syntax">general_pointer</span><span class="plain-syntax"> </span><span class="identifier-syntax">wrapping</span><span class="plain-syntax">) {</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">T</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 tree"</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">wrapping</span><span class="plain-syntax">.</span><span class="element-syntax">run_time_type_code</span><span class="plain-syntax"> == -1)</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">internal_error</span><span class="plain-syntax">(</span><span class="string-syntax">"no reference given"</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">type</span><span class="plain-syntax">-></span><span class="element-syntax">required_MT</span><span class="plain-syntax"> >= </span><span class="constant-syntax">0</span><span class="plain-syntax">)</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">wrapping</span><span class="plain-syntax">.</span><span class="element-syntax">run_time_type_code</span><span class="plain-syntax"> != </span><span class="identifier-syntax">type</span><span class="plain-syntax">-></span><span class="element-syntax">required_MT</span><span class="plain-syntax">)</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">internal_error</span><span class="plain-syntax">(</span><span class="string-syntax">"wrong reference type"</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">tree_node</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">tree_node</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">N</span><span class="plain-syntax">-></span><span class="element-syntax">content</span><span class="plain-syntax"> = </span><span class="identifier-syntax">wrapping</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">N</span><span class="plain-syntax">-></span><span class="element-syntax">owner</span><span class="plain-syntax"> = </span><span class="identifier-syntax">T</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">N</span><span class="plain-syntax">-></span><span class="element-syntax">type</span><span class="plain-syntax"> = </span><span class="identifier-syntax">type</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">N</span><span class="plain-syntax">-></span><span class="element-syntax">parent</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">N</span><span class="plain-syntax">-></span><span class="element-syntax">child</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">N</span><span class="plain-syntax">-></span><span class="element-syntax">next</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">;</span>
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<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>
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<span class="plain-syntax">}</span>
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</pre>
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<p class="commentary firstcommentary"><a id="SP5"></a><b>§5. </b>A convenient abbreviation for a common manoeuvre:
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</p>
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<pre class="displayed-code all-displayed-code code-font">
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<span class="reserved-syntax">tree_node</span><span class="plain-syntax"> *</span><span class="function-syntax">Trees::new_child</span><span class="plain-syntax">(</span><span class="reserved-syntax">tree_node</span><span class="plain-syntax"> *</span><span class="identifier-syntax">of</span><span class="plain-syntax">, </span><span class="reserved-syntax">tree_node_type</span><span class="plain-syntax"> *</span><span class="identifier-syntax">type</span><span class="plain-syntax">, </span><span class="reserved-syntax">general_pointer</span><span class="plain-syntax"> </span><span class="identifier-syntax">wrapping</span><span class="plain-syntax">) {</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">tree_node</span><span class="plain-syntax"> *</span><span class="identifier-syntax">N</span><span class="plain-syntax"> = </span><a href="2-trs.html#SP4" class="function-link"><span class="function-syntax">Trees::new_node</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">of</span><span class="plain-syntax">-></span><span class="element-syntax">owner</span><span class="plain-syntax">, </span><span class="identifier-syntax">type</span><span class="plain-syntax">, </span><span class="identifier-syntax">wrapping</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><a href="2-trs.html#SP11" class="function-link"><span class="function-syntax">Trees::make_child</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">N</span><span class="plain-syntax">, </span><span class="identifier-syntax">of</span><span class="plain-syntax">);</span>
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<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>
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<span class="plain-syntax">}</span>
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</pre>
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<p class="commentary firstcommentary"><a id="SP6"></a><b>§6. Types. </b>The above will provide for multiple different types of tree to be used for
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different purposes. Heterogeneous trees allow the coder to make dangerously
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type-unsafe structures, so we want to hedge them in with self-imposed
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constraints:
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</p>
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<pre class="displayed-code all-displayed-code code-font">
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<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">tree_type</span><span class="plain-syntax"> {</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="reserved-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">name</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> (*</span><span class="identifier-syntax">verify_root</span><span class="plain-syntax">)(</span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="reserved-syntax">tree_node</span><span class="plain-syntax"> *); </span><span class="comment-syntax"> function to vet the root node</span>
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<span class="plain-syntax"> </span><span class="constant-syntax">MEMORY_MANAGEMENT</span>
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<span class="plain-syntax">} </span><span class="reserved-syntax">tree_type</span><span class="plain-syntax">;</span>
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</pre>
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<ul class="endnotetexts"><li>The structure tree_type is private to this section.</li></ul>
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<p class="commentary firstcommentary"><a id="SP7"></a><b>§7. </b></p>
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<pre class="displayed-code all-displayed-code code-font">
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<span class="reserved-syntax">tree_type</span><span class="plain-syntax"> *</span><span class="function-syntax">Trees::new_type</span><span class="plain-syntax">(</span><span class="reserved-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">name</span><span class="plain-syntax">, </span><span class="reserved-syntax">int</span><span class="plain-syntax"> (*</span><span class="identifier-syntax">verifier</span><span class="plain-syntax">)(</span><span class="reserved-syntax">tree_node</span><span class="plain-syntax"> *)) {</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">tree_type</span><span class="plain-syntax"> *</span><span class="identifier-syntax">T</span><span class="plain-syntax"> = </span><span class="identifier-syntax">CREATE</span><span class="plain-syntax">(</span><span class="reserved-syntax">tree_type</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">T</span><span class="plain-syntax">-></span><span class="element-syntax">name</span><span class="plain-syntax"> = </span><a href="4-sm.html#SP3" class="function-link"><span class="function-syntax">Str::duplicate</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">name</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">T</span><span class="plain-syntax">-></span><span class="element-syntax">verify_root</span><span class="plain-syntax"> = </span><span class="identifier-syntax">verifier</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">T</span><span class="plain-syntax">;</span>
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<span class="plain-syntax">}</span>
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</pre>
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<p class="commentary firstcommentary"><a id="SP8"></a><b>§8. </b>Each node in a tree also has a type. Whenever the children of a node change,
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they are re-verified by the <span class="extract"><span class="extract-syntax">verify_children</span></span>.
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</p>
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<pre class="displayed-code all-displayed-code code-font">
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<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">tree_node_type</span><span class="plain-syntax"> {</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="reserved-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">node_type_name</span><span class="plain-syntax">; </span><span class="comment-syntax"> text such as </span><span class="extract"><span class="extract-syntax">I"INVOCATION"</span></span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">required_MT</span><span class="plain-syntax">; </span><span class="comment-syntax"> if any; or negative for no restriction</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> (*</span><span class="identifier-syntax">verify_children</span><span class="plain-syntax">)(</span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="reserved-syntax">tree_node</span><span class="plain-syntax"> *); </span><span class="comment-syntax"> function to vet the children</span>
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<span class="plain-syntax"> </span><span class="constant-syntax">MEMORY_MANAGEMENT</span>
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<span class="plain-syntax">} </span><span class="reserved-syntax">tree_node_type</span><span class="plain-syntax">;</span>
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</pre>
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<ul class="endnotetexts"><li>The structure tree_node_type is private to this section.</li></ul>
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<p class="commentary firstcommentary"><a id="SP9"></a><b>§9. </b></p>
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<pre class="displayed-code all-displayed-code code-font">
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<span class="reserved-syntax">tree_node_type</span><span class="plain-syntax"> *</span><span class="function-syntax">Trees::new_node_type</span><span class="plain-syntax">(</span><span class="reserved-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">name</span><span class="plain-syntax">, </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">req</span><span class="plain-syntax">,</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> (*</span><span class="identifier-syntax">verifier</span><span class="plain-syntax">)(</span><span class="reserved-syntax">tree_node</span><span class="plain-syntax"> *)) {</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">tree_node_type</span><span class="plain-syntax"> *</span><span class="identifier-syntax">NT</span><span class="plain-syntax"> = </span><span class="identifier-syntax">CREATE</span><span class="plain-syntax">(</span><span class="reserved-syntax">tree_node_type</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">NT</span><span class="plain-syntax">-></span><span class="element-syntax">node_type_name</span><span class="plain-syntax"> = </span><a href="4-sm.html#SP3" class="function-link"><span class="function-syntax">Str::duplicate</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">name</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">NT</span><span class="plain-syntax">-></span><span class="element-syntax">required_MT</span><span class="plain-syntax"> = </span><span class="identifier-syntax">req</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">NT</span><span class="plain-syntax">-></span><span class="element-syntax">verify_children</span><span class="plain-syntax"> = </span><span class="identifier-syntax">verifier</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">NT</span><span class="plain-syntax">;</span>
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<span class="plain-syntax">}</span>
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</pre>
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<p class="commentary firstcommentary"><a id="SP10"></a><b>§10. Hierarchy. </b>A special function is needed to choose the root node; and note that this is
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verified.
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</p>
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<pre class="displayed-code all-displayed-code code-font">
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<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Trees::make_root</span><span class="plain-syntax">(</span><span class="reserved-syntax">heterogeneous_tree</span><span class="plain-syntax"> *</span><span class="identifier-syntax">T</span><span class="plain-syntax">, </span><span class="reserved-syntax">tree_node</span><span class="plain-syntax"> *</span><span class="identifier-syntax">N</span><span class="plain-syntax">) {</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">T</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 tree"</span><span class="plain-syntax">);</span>
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<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 node"</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">N</span><span class="plain-syntax">-></span><span class="element-syntax">owner</span><span class="plain-syntax"> = </span><span class="identifier-syntax">T</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">T</span><span class="plain-syntax">-></span><span class="element-syntax">root</span><span class="plain-syntax"> = </span><span class="identifier-syntax">N</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">N</span><span class="plain-syntax">-></span><span class="element-syntax">parent</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">N</span><span class="plain-syntax">-></span><span class="element-syntax">next</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">T</span><span class="plain-syntax">-></span><span class="identifier-syntax">type</span><span class="plain-syntax">-></span><span class="element-syntax">verify_root</span><span class="plain-syntax">)</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((*(</span><span class="identifier-syntax">T</span><span class="plain-syntax">-></span><span class="element-syntax">type</span><span class="plain-syntax">-></span><span class="element-syntax">verify_root</span><span class="plain-syntax">))(</span><span class="identifier-syntax">N</span><span class="plain-syntax">) == </span><span class="constant-syntax">FALSE</span><span class="plain-syntax">)</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">internal_error</span><span class="plain-syntax">(</span><span class="string-syntax">"disallowed node as root"</span><span class="plain-syntax">);</span>
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<span class="plain-syntax">}</span>
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<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Trees::remove_root</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">Trees::remove_root</span></span>:<br/><a href="2-trs.html#SP11">§11</a>, <a href="2-trs.html#SP12">§12</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">heterogeneous_tree</span><span class="plain-syntax"> *</span><span class="identifier-syntax">T</span><span class="plain-syntax">) {</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">T</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 tree"</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">T</span><span class="plain-syntax">-></span><span class="element-syntax">root</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">;</span>
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<span class="plain-syntax">}</span>
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</pre>
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<p class="commentary firstcommentary"><a id="SP11"></a><b>§11. </b>Otherwise, nodes are placed in a tree with respect to other nodes:
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</p>
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<pre class="displayed-code all-displayed-code code-font">
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<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Trees::make_child</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">Trees::make_child</span></span>:<br/><a href="2-trs.html#SP5">§5</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">tree_node</span><span class="plain-syntax"> *</span><span class="identifier-syntax">N</span><span class="plain-syntax">, </span><span class="reserved-syntax">tree_node</span><span class="plain-syntax"> *</span><span class="identifier-syntax">of</span><span class="plain-syntax">) {</span>
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<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 node"</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">of</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 node"</span><span class="plain-syntax">);</span>
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<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">N</span><span class="plain-syntax">-></span><span class="element-syntax">owner</span><span class="plain-syntax">-></span><span class="element-syntax">root</span><span class="plain-syntax">) </span><a href="2-trs.html#SP10" class="function-link"><span class="function-syntax">Trees::remove_root</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">N</span><span class="plain-syntax">-></span><span class="element-syntax">owner</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">N</span><span class="plain-syntax">-></span><span class="element-syntax">owner</span><span class="plain-syntax"> = </span><span class="identifier-syntax">of</span><span class="plain-syntax">-></span><span class="element-syntax">owner</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">N</span><span class="plain-syntax">-></span><span class="element-syntax">parent</span><span class="plain-syntax"> = </span><span class="identifier-syntax">of</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">N</span><span class="plain-syntax">-></span><span class="element-syntax">next</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">of</span><span class="plain-syntax">-></span><span class="element-syntax">child</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">)</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">of</span><span class="plain-syntax">-></span><span class="element-syntax">child</span><span class="plain-syntax"> = </span><span class="identifier-syntax">N</span><span class="plain-syntax">;</span>
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|
<span class="plain-syntax"> </span><span class="reserved-syntax">else</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">for</span><span class="plain-syntax"> (</span><span class="reserved-syntax">tree_node</span><span class="plain-syntax"> *</span><span class="identifier-syntax">S</span><span class="plain-syntax"> = </span><span class="identifier-syntax">of</span><span class="plain-syntax">-></span><span class="element-syntax">child</span><span class="plain-syntax">; </span><span class="identifier-syntax">S</span><span class="plain-syntax">; </span><span class="identifier-syntax">S</span><span class="plain-syntax"> = </span><span class="identifier-syntax">S</span><span class="plain-syntax">-></span><span class="element-syntax">next</span><span class="plain-syntax">)</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">S</span><span class="plain-syntax">-></span><span class="element-syntax">next</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) {</span>
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|
<span class="plain-syntax"> </span><span class="identifier-syntax">S</span><span class="plain-syntax">-></span><span class="element-syntax">next</span><span class="plain-syntax"> = </span><span class="identifier-syntax">N</span><span class="plain-syntax">; </span><span class="reserved-syntax">break</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> }</span>
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<span class="plain-syntax"> </span><a href="2-trs.html#SP12" class="function-link"><span class="function-syntax">Trees::verify_children</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">of</span><span class="plain-syntax">);</span>
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|
<span class="plain-syntax">}</span>
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|
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<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Trees::make_eldest_child</span><span class="plain-syntax">(</span><span class="reserved-syntax">tree_node</span><span class="plain-syntax"> *</span><span class="identifier-syntax">N</span><span class="plain-syntax">, </span><span class="reserved-syntax">tree_node</span><span class="plain-syntax"> *</span><span class="identifier-syntax">of</span><span class="plain-syntax">) {</span>
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|
<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 node"</span><span class="plain-syntax">);</span>
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|
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">of</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 node"</span><span class="plain-syntax">);</span>
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|
<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">N</span><span class="plain-syntax">-></span><span class="element-syntax">owner</span><span class="plain-syntax">-></span><span class="element-syntax">root</span><span class="plain-syntax">) </span><a href="2-trs.html#SP10" class="function-link"><span class="function-syntax">Trees::remove_root</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">N</span><span class="plain-syntax">-></span><span class="element-syntax">owner</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">N</span><span class="plain-syntax">-></span><span class="element-syntax">owner</span><span class="plain-syntax"> = </span><span class="identifier-syntax">of</span><span class="plain-syntax">-></span><span class="element-syntax">owner</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">N</span><span class="plain-syntax">-></span><span class="element-syntax">parent</span><span class="plain-syntax"> = </span><span class="identifier-syntax">of</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">N</span><span class="plain-syntax">-></span><span class="element-syntax">next</span><span class="plain-syntax"> = </span><span class="identifier-syntax">of</span><span class="plain-syntax">-></span><span class="element-syntax">child</span><span class="plain-syntax">;</span>
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|
<span class="plain-syntax"> </span><span class="identifier-syntax">of</span><span class="plain-syntax">-></span><span class="element-syntax">child</span><span class="plain-syntax"> = </span><span class="identifier-syntax">N</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><a href="2-trs.html#SP12" class="function-link"><span class="function-syntax">Trees::verify_children</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">of</span><span class="plain-syntax">);</span>
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|
<span class="plain-syntax">}</span>
|
|
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|
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Trees::make_sibling</span><span class="plain-syntax">(</span><span class="reserved-syntax">tree_node</span><span class="plain-syntax"> *</span><span class="identifier-syntax">N</span><span class="plain-syntax">, </span><span class="reserved-syntax">tree_node</span><span class="plain-syntax"> *</span><span class="identifier-syntax">of</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 node"</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">of</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 node"</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">N</span><span class="plain-syntax">-></span><span class="element-syntax">owner</span><span class="plain-syntax">-></span><span class="element-syntax">root</span><span class="plain-syntax">) </span><a href="2-trs.html#SP10" class="function-link"><span class="function-syntax">Trees::remove_root</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">N</span><span class="plain-syntax">-></span><span class="element-syntax">owner</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">of</span><span class="plain-syntax"> == </span><span class="identifier-syntax">of</span><span class="plain-syntax">-></span><span class="element-syntax">owner</span><span class="plain-syntax">-></span><span class="element-syntax">root</span><span class="plain-syntax">)</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">internal_error</span><span class="plain-syntax">(</span><span class="string-syntax">"nodes cannot be siblings of the root"</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">N</span><span class="plain-syntax">-></span><span class="element-syntax">owner</span><span class="plain-syntax"> = </span><span class="identifier-syntax">of</span><span class="plain-syntax">-></span><span class="element-syntax">owner</span><span class="plain-syntax">;</span>
|
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<span class="plain-syntax"> </span><span class="identifier-syntax">N</span><span class="plain-syntax">-></span><span class="element-syntax">parent</span><span class="plain-syntax"> = </span><span class="identifier-syntax">of</span><span class="plain-syntax">-></span><span class="element-syntax">parent</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">N</span><span class="plain-syntax">-></span><span class="element-syntax">next</span><span class="plain-syntax"> = </span><span class="identifier-syntax">of</span><span class="plain-syntax">-></span><span class="element-syntax">next</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">of</span><span class="plain-syntax">-></span><span class="element-syntax">next</span><span class="plain-syntax"> = </span><span class="identifier-syntax">N</span><span class="plain-syntax">;</span>
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|
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">of</span><span class="plain-syntax">-></span><span class="element-syntax">parent</span><span class="plain-syntax">) </span><a href="2-trs.html#SP12" class="function-link"><span class="function-syntax">Trees::verify_children</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">of</span><span class="plain-syntax">-></span><span class="element-syntax">parent</span><span class="plain-syntax">);</span>
|
|
<span class="plain-syntax">}</span>
|
|
</pre>
|
|
<p class="commentary firstcommentary"><a id="SP12"></a><b>§12. </b>Removing a node from a tree does not change its ownership — it still belongs
|
|
to that tree.
|
|
</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">Trees::remove</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">Trees::remove</span></span>:<br/><a href="2-trs.html#SP14">§14</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">tree_node</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="identifier-syntax">internal_error</span><span class="plain-syntax">(</span><span class="string-syntax">"no node"</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">N</span><span class="plain-syntax">-></span><span class="element-syntax">owner</span><span class="plain-syntax">-></span><span class="element-syntax">root</span><span class="plain-syntax">) { </span><a href="2-trs.html#SP10" class="function-link"><span class="function-syntax">Trees::remove_root</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">N</span><span class="plain-syntax">-></span><span class="element-syntax">owner</span><span class="plain-syntax">); </span><span class="reserved-syntax">return</span><span class="plain-syntax">; }</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">tree_node</span><span class="plain-syntax"> *</span><span class="identifier-syntax">p</span><span class="plain-syntax"> = </span><span class="identifier-syntax">N</span><span class="plain-syntax">-></span><span class="element-syntax">parent</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">parent</span><span class="plain-syntax">-></span><span class="element-syntax">child</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">-></span><span class="identifier-syntax">parent</span><span class="plain-syntax">-></span><span class="element-syntax">child</span><span class="plain-syntax"> = </span><span class="identifier-syntax">N</span><span class="plain-syntax">-></span><span class="element-syntax">next</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">else</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">for</span><span class="plain-syntax"> (</span><span class="reserved-syntax">tree_node</span><span class="plain-syntax"> *</span><span class="identifier-syntax">S</span><span class="plain-syntax"> = </span><span class="identifier-syntax">N</span><span class="plain-syntax">-></span><span class="element-syntax">parent</span><span class="plain-syntax">-></span><span class="element-syntax">child</span><span class="plain-syntax">; </span><span class="identifier-syntax">S</span><span class="plain-syntax">; </span><span class="identifier-syntax">S</span><span class="plain-syntax"> = </span><span class="identifier-syntax">S</span><span class="plain-syntax">-></span><span class="element-syntax">next</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">S</span><span class="plain-syntax">-></span><span class="element-syntax">next</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">S</span><span class="plain-syntax">-></span><span class="element-syntax">next</span><span class="plain-syntax"> = </span><span class="identifier-syntax">N</span><span class="plain-syntax">-></span><span class="element-syntax">next</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">N</span><span class="plain-syntax">-></span><span class="element-syntax">parent</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">N</span><span class="plain-syntax">-></span><span class="element-syntax">next</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NULL</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">p</span><span class="plain-syntax">) </span><a href="2-trs.html#SP12" class="function-link"><span class="function-syntax">Trees::verify_children</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">p</span><span class="plain-syntax">);</span>
|
|
<span class="plain-syntax">}</span>
|
|
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<span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="function-syntax">Trees::verify_children</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">Trees::verify_children</span></span>:<br/><a href="2-trs.html#SP11">§11</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">tree_node</span><span class="plain-syntax"> *</span><span class="identifier-syntax">N</span><span class="plain-syntax">) {</span>
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<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 node"</span><span class="plain-syntax">);</span>
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<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">type</span><span class="plain-syntax">-></span><span class="element-syntax">verify_children</span><span class="plain-syntax">)</span>
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<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="element-syntax">type</span><span class="plain-syntax">-></span><span class="element-syntax">verify_children</span><span class="plain-syntax">))(</span><span class="identifier-syntax">N</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="constant-syntax">TRUE</span><span class="plain-syntax">;</span>
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<span class="plain-syntax">}</span>
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</pre>
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<p class="commentary firstcommentary"><a id="SP13"></a><b>§13. Traversals. </b>These two functions allow us to traverse the tree, visiting each node along
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the way and carrying a state as we do. The distinction is that <a href="2-trs.html#SP13" class="internal">Trees::traverse_from</a>
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iterates from and then below the given node, but doesn't go through its siblings,
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whereas <a href="2-trs.html#SP13" class="internal">Trees::traverse</a> does.
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</p>
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<p class="commentary">Note that it is legal to traverse the empty node, and does nothing.
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</p>
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<pre class="displayed-code all-displayed-code code-font">
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<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Trees::traverse_tree</span><span class="plain-syntax">(</span><span class="reserved-syntax">heterogeneous_tree</span><span class="plain-syntax"> *</span><span class="identifier-syntax">T</span><span class="plain-syntax">,</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> (*</span><span class="identifier-syntax">visitor</span><span class="plain-syntax">)(</span><span class="reserved-syntax">tree_node</span><span class="plain-syntax"> *, </span><span class="reserved-syntax">void</span><span class="plain-syntax"> *, </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">L</span><span class="plain-syntax">), </span><span class="reserved-syntax">void</span><span class="plain-syntax"> *</span><span class="identifier-syntax">state</span><span class="plain-syntax">) {</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">T</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 tree"</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><a href="2-trs.html#SP13" class="function-link"><span class="function-syntax">Trees::traverse_from</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">T</span><span class="plain-syntax">-></span><span class="element-syntax">root</span><span class="plain-syntax">, </span><span class="identifier-syntax">visitor</span><span class="plain-syntax">, </span><span class="identifier-syntax">state</span><span class="plain-syntax">, </span><span class="constant-syntax">0</span><span class="plain-syntax">);</span>
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<span class="plain-syntax">}</span>
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<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Trees::traverse_from</span><span class="plain-syntax">(</span><span class="reserved-syntax">tree_node</span><span class="plain-syntax"> *</span><span class="identifier-syntax">N</span><span class="plain-syntax">,</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> (*</span><span class="identifier-syntax">visitor</span><span class="plain-syntax">)(</span><span class="reserved-syntax">tree_node</span><span class="plain-syntax"> *, </span><span class="reserved-syntax">void</span><span class="plain-syntax"> *, </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">L</span><span class="plain-syntax">), </span><span class="reserved-syntax">void</span><span class="plain-syntax"> *</span><span class="identifier-syntax">state</span><span class="plain-syntax">, </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">L</span><span class="plain-syntax">) {</span>
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<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>
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<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((*</span><span class="identifier-syntax">visitor</span><span class="plain-syntax">)(</span><span class="identifier-syntax">N</span><span class="plain-syntax">, </span><span class="identifier-syntax">state</span><span class="plain-syntax">, </span><span class="identifier-syntax">L</span><span class="plain-syntax">))</span>
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<span class="plain-syntax"> </span><a href="2-trs.html#SP13" class="function-link"><span class="function-syntax">Trees::traverse</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">N</span><span class="plain-syntax">-></span><span class="element-syntax">child</span><span class="plain-syntax">, </span><span class="identifier-syntax">visitor</span><span class="plain-syntax">, </span><span class="identifier-syntax">state</span><span class="plain-syntax">, </span><span class="identifier-syntax">L</span><span class="plain-syntax">+1);</span>
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<span class="plain-syntax">}</span>
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<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Trees::traverse</span><span class="plain-syntax">(</span><span class="reserved-syntax">tree_node</span><span class="plain-syntax"> *</span><span class="identifier-syntax">N</span><span class="plain-syntax">,</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> (*</span><span class="identifier-syntax">visitor</span><span class="plain-syntax">)(</span><span class="reserved-syntax">tree_node</span><span class="plain-syntax"> *, </span><span class="reserved-syntax">void</span><span class="plain-syntax"> *, </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">L</span><span class="plain-syntax">), </span><span class="reserved-syntax">void</span><span class="plain-syntax"> *</span><span class="identifier-syntax">state</span><span class="plain-syntax">, </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">L</span><span class="plain-syntax">) {</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">for</span><span class="plain-syntax"> (</span><span class="reserved-syntax">tree_node</span><span class="plain-syntax"> *</span><span class="identifier-syntax">M</span><span class="plain-syntax"> = </span><span class="identifier-syntax">N</span><span class="plain-syntax">; </span><span class="identifier-syntax">M</span><span class="plain-syntax">; </span><span class="identifier-syntax">M</span><span class="plain-syntax"> = </span><span class="identifier-syntax">M</span><span class="plain-syntax">-></span><span class="element-syntax">next</span><span class="plain-syntax">)</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((*</span><span class="identifier-syntax">visitor</span><span class="plain-syntax">)(</span><span class="identifier-syntax">M</span><span class="plain-syntax">, </span><span class="identifier-syntax">state</span><span class="plain-syntax">, </span><span class="identifier-syntax">L</span><span class="plain-syntax">))</span>
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<span class="plain-syntax"> </span><a href="2-trs.html#SP13" class="function-link"><span class="function-syntax">Trees::traverse</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">M</span><span class="plain-syntax">-></span><span class="element-syntax">child</span><span class="plain-syntax">, </span><span class="identifier-syntax">visitor</span><span class="plain-syntax">, </span><span class="identifier-syntax">state</span><span class="plain-syntax">, </span><span class="identifier-syntax">L</span><span class="plain-syntax">+1);</span>
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<span class="plain-syntax">}</span>
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</pre>
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<p class="commentary firstcommentary"><a id="SP14"></a><b>§14. </b></p>
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<pre class="displayed-code all-displayed-code code-font">
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<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Trees::prune_tree</span><span class="plain-syntax">(</span><span class="reserved-syntax">heterogeneous_tree</span><span class="plain-syntax"> *</span><span class="identifier-syntax">T</span><span class="plain-syntax">,</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> (*</span><span class="identifier-syntax">visitor</span><span class="plain-syntax">)(</span><span class="reserved-syntax">tree_node</span><span class="plain-syntax"> *, </span><span class="reserved-syntax">void</span><span class="plain-syntax"> *), </span><span class="reserved-syntax">void</span><span class="plain-syntax"> *</span><span class="identifier-syntax">state</span><span class="plain-syntax">) {</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">T</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 tree"</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><a href="2-trs.html#SP14" class="function-link"><span class="function-syntax">Trees::prune_from</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">T</span><span class="plain-syntax">-></span><span class="element-syntax">root</span><span class="plain-syntax">, </span><span class="identifier-syntax">visitor</span><span class="plain-syntax">, </span><span class="identifier-syntax">state</span><span class="plain-syntax">);</span>
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<span class="plain-syntax">}</span>
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<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Trees::prune_from</span><span class="plain-syntax">(</span><span class="reserved-syntax">tree_node</span><span class="plain-syntax"> *</span><span class="identifier-syntax">N</span><span class="plain-syntax">,</span>
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|
<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> (*</span><span class="identifier-syntax">visitor</span><span class="plain-syntax">)(</span><span class="reserved-syntax">tree_node</span><span class="plain-syntax"> *, </span><span class="reserved-syntax">void</span><span class="plain-syntax"> *), </span><span class="reserved-syntax">void</span><span class="plain-syntax"> *</span><span class="identifier-syntax">state</span><span class="plain-syntax">) {</span>
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<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>
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|
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((*</span><span class="identifier-syntax">visitor</span><span class="plain-syntax">)(</span><span class="identifier-syntax">N</span><span class="plain-syntax">, </span><span class="identifier-syntax">state</span><span class="plain-syntax">))</span>
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<span class="plain-syntax"> </span><a href="2-trs.html#SP12" class="function-link"><span class="function-syntax">Trees::remove</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">N</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">else</span>
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<span class="plain-syntax"> </span><a href="2-trs.html#SP14" class="function-link"><span class="function-syntax">Trees::prune</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">N</span><span class="plain-syntax">-></span><span class="element-syntax">child</span><span class="plain-syntax">, </span><span class="identifier-syntax">visitor</span><span class="plain-syntax">, </span><span class="identifier-syntax">state</span><span class="plain-syntax">);</span>
|
|
<span class="plain-syntax"> }</span>
|
|
<span class="plain-syntax">}</span>
|
|
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<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Trees::prune</span><span class="plain-syntax">(</span><span class="reserved-syntax">tree_node</span><span class="plain-syntax"> *</span><span class="identifier-syntax">N</span><span class="plain-syntax">,</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> (*</span><span class="identifier-syntax">visitor</span><span class="plain-syntax">)(</span><span class="reserved-syntax">tree_node</span><span class="plain-syntax"> *, </span><span class="reserved-syntax">void</span><span class="plain-syntax"> *), </span><span class="reserved-syntax">void</span><span class="plain-syntax"> *</span><span class="identifier-syntax">state</span><span class="plain-syntax">) {</span>
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|
<span class="plain-syntax"> </span><span class="reserved-syntax">for</span><span class="plain-syntax"> (</span><span class="reserved-syntax">tree_node</span><span class="plain-syntax"> *</span><span class="identifier-syntax">M</span><span class="plain-syntax"> = </span><span class="identifier-syntax">N</span><span class="plain-syntax">, *</span><span class="identifier-syntax">next_M</span><span class="plain-syntax"> = </span><span class="identifier-syntax">N</span><span class="plain-syntax">?(</span><span class="identifier-syntax">N</span><span class="plain-syntax">-></span><span class="element-syntax">next</span><span class="plain-syntax">):</span><span class="identifier-syntax">NULL</span><span class="plain-syntax">; </span><span class="identifier-syntax">M</span><span class="plain-syntax">; </span><span class="identifier-syntax">M</span><span class="plain-syntax"> = </span><span class="identifier-syntax">next_M</span><span class="plain-syntax">, </span><span class="identifier-syntax">next_M</span><span class="plain-syntax"> = </span><span class="identifier-syntax">M</span><span class="plain-syntax">?(</span><span class="identifier-syntax">M</span><span class="plain-syntax">-></span><span class="element-syntax">next</span><span class="plain-syntax">):</span><span class="identifier-syntax">NULL</span><span class="plain-syntax">)</span>
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|
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((*</span><span class="identifier-syntax">visitor</span><span class="plain-syntax">)(</span><span class="identifier-syntax">M</span><span class="plain-syntax">, </span><span class="identifier-syntax">state</span><span class="plain-syntax">))</span>
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<span class="plain-syntax"> </span><a href="2-trs.html#SP12" class="function-link"><span class="function-syntax">Trees::remove</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">M</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">else</span>
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<span class="plain-syntax"> </span><a href="2-trs.html#SP14" class="function-link"><span class="function-syntax">Trees::prune</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">M</span><span class="plain-syntax">-></span><span class="element-syntax">child</span><span class="plain-syntax">, </span><span class="identifier-syntax">visitor</span><span class="plain-syntax">, </span><span class="identifier-syntax">state</span><span class="plain-syntax">);</span>
|
|
<span class="plain-syntax">}</span>
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</pre>
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<hr class="tocbar">
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<ul class="toc"><li><a href="2-dct.html">Back to 'Dictionaries'</a></li><li><i>(This section ends Chapter 2: Memory, Streams and Collections.)</i></li></ul><hr class="tocbar">
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