340 lines
47 KiB
HTML
340 lines
47 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-src/Figures/Octagram184x184.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="https://github.com/ganelson/inweb"><img src="../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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<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="inwebparagraph"><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="display">
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<span class="reserved">typedef</span><span class="plain"> </span><span class="reserved">struct</span><span class="plain"> </span><span class="reserved">heterogeneous_tree</span><span class="plain"> {</span>
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<span class="reserved">struct</span><span class="plain"> </span><span class="reserved">tree_type</span><span class="plain"> *</span><span class="identifier">type</span><span class="plain">;</span>
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<span class="reserved">struct</span><span class="plain"> </span><span class="reserved">tree_node</span><span class="plain"> *</span><span class="identifier">root</span><span class="plain">;</span>
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<span class="constant">MEMORY_MANAGEMENT</span>
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<span class="plain">} </span><span class="reserved">heterogeneous_tree</span><span class="plain">;</span>
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</pre>
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<p class="inwebparagraph"></p>
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<p class="endnote">The structure heterogeneous_tree is private to this section.</p>
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<p class="inwebparagraph"><a id="SP2"></a><b>§2. </b></p>
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<pre class="display">
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<span class="reserved">heterogeneous_tree</span><span class="plain"> *</span><span class="functiontext">Trees::new<button class="popup" onclick="togglePopup('usagePopup150')">...<span class="popuptext" id="usagePopup150">Usage of <b>Trees::new</b>:<br>none</span></button></span><span class="plain">(</span><span class="reserved">tree_type</span><span class="plain"> *</span><span class="identifier">type</span><span class="plain">) {</span>
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<span class="reserved">heterogeneous_tree</span><span class="plain"> *</span><span class="identifier">T</span><span class="plain"> = </span><span class="identifier">CREATE</span><span class="plain">(</span><span class="reserved">heterogeneous_tree</span><span class="plain">);</span>
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<span class="identifier">T</span><span class="plain">-></span><span class="element">type</span><span class="plain"> = </span><span class="identifier">type</span><span class="plain">;</span>
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<span class="identifier">T</span><span class="plain">-></span><span class="element">root</span><span class="plain"> = </span><span class="identifier">NULL</span><span class="plain">;</span>
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<span class="reserved">return</span><span class="plain"> </span><span class="identifier">T</span><span class="plain">;</span>
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<span class="plain">}</span>
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</pre>
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<p class="inwebparagraph"></p>
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<p class="inwebparagraph"><a id="SP3"></a><b>§3. </b></p>
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<pre class="display">
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<span class="reserved">typedef</span><span class="plain"> </span><span class="reserved">struct</span><span class="plain"> </span><span class="reserved">tree_node</span><span class="plain"> {</span>
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<span class="reserved">struct</span><span class="plain"> </span><span class="reserved">heterogeneous_tree</span><span class="plain"> *</span><span class="identifier">owner</span><span class="plain">;</span>
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<span class="reserved">struct</span><span class="plain"> </span><span class="reserved">tree_node_type</span><span class="plain"> *</span><span class="identifier">type</span><span class="plain">;</span>
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<span class="reserved">struct</span><span class="plain"> </span><span class="reserved">general_pointer</span><span class="plain"> </span><span class="identifier">content</span><span class="plain">;</span>
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<span class="reserved">struct</span><span class="plain"> </span><span class="reserved">tree_node</span><span class="plain"> *</span><span class="identifier">next</span><span class="plain">;</span>
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<span class="reserved">struct</span><span class="plain"> </span><span class="reserved">tree_node</span><span class="plain"> *</span><span class="identifier">parent</span><span class="plain">;</span>
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<span class="reserved">struct</span><span class="plain"> </span><span class="reserved">tree_node</span><span class="plain"> *</span><span class="identifier">child</span><span class="plain">;</span>
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<span class="constant">MEMORY_MANAGEMENT</span>
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<span class="plain">} </span><span class="reserved">tree_node</span><span class="plain">;</span>
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</pre>
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<p class="inwebparagraph"></p>
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<p class="endnote">The structure tree_node is accessed in 2/mmr, 4/taa and here.</p>
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<p class="inwebparagraph"><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="display">
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<span class="reserved">tree_node</span><span class="plain"> *</span><span class="functiontext">Trees::new_node<button class="popup" onclick="togglePopup('usagePopup151')">...<span class="popuptext" id="usagePopup151">Usage of <b>Trees::new_node</b>:<br><a href="2-trs.html#SP5">§5</a></span></button></span><span class="plain">(</span><span class="reserved">heterogeneous_tree</span><span class="plain"> *</span><span class="identifier">T</span><span class="plain">, </span><span class="reserved">tree_node_type</span><span class="plain"> *</span><span class="identifier">type</span><span class="plain">, </span><span class="reserved">general_pointer</span><span class="plain"> </span><span class="identifier">wrapping</span><span class="plain">) {</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">T</span><span class="plain"> == </span><span class="identifier">NULL</span><span class="plain">) </span><span class="identifier">internal_error</span><span class="plain">(</span><span class="string">"no tree"</span><span class="plain">);</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">wrapping</span><span class="plain">.</span><span class="element">run_time_type_code</span><span class="plain"> == -1)</span>
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<span class="identifier">internal_error</span><span class="plain">(</span><span class="string">"no reference given"</span><span class="plain">);</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">type</span><span class="plain">-></span><span class="identifier">required_MT</span><span class="plain"> >= </span><span class="constant">0</span><span class="plain">)</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">wrapping</span><span class="plain">.</span><span class="element">run_time_type_code</span><span class="plain"> != </span><span class="identifier">type</span><span class="plain">-></span><span class="element">required_MT</span><span class="plain">)</span>
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<span class="identifier">internal_error</span><span class="plain">(</span><span class="string">"wrong reference type"</span><span class="plain">);</span>
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<span class="reserved">tree_node</span><span class="plain"> *</span><span class="identifier">N</span><span class="plain"> = </span><span class="identifier">CREATE</span><span class="plain">(</span><span class="reserved">tree_node</span><span class="plain">);</span>
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<span class="identifier">N</span><span class="plain">-></span><span class="element">content</span><span class="plain"> = </span><span class="identifier">wrapping</span><span class="plain">;</span>
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<span class="identifier">N</span><span class="plain">-></span><span class="element">owner</span><span class="plain"> = </span><span class="identifier">T</span><span class="plain">;</span>
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<span class="identifier">N</span><span class="plain">-></span><span class="element">type</span><span class="plain"> = </span><span class="identifier">type</span><span class="plain">;</span>
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<span class="identifier">N</span><span class="plain">-></span><span class="element">parent</span><span class="plain"> = </span><span class="identifier">NULL</span><span class="plain">;</span>
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<span class="identifier">N</span><span class="plain">-></span><span class="element">child</span><span class="plain"> = </span><span class="identifier">NULL</span><span class="plain">;</span>
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<span class="identifier">N</span><span class="plain">-></span><span class="element">next</span><span class="plain"> = </span><span class="identifier">NULL</span><span class="plain">;</span>
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<span class="reserved">return</span><span class="plain"> </span><span class="identifier">N</span><span class="plain">;</span>
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<span class="plain">}</span>
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</pre>
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<p class="inwebparagraph"></p>
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<p class="inwebparagraph"><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="display">
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<span class="reserved">tree_node</span><span class="plain"> *</span><span class="functiontext">Trees::new_child<button class="popup" onclick="togglePopup('usagePopup152')">...<span class="popuptext" id="usagePopup152">Usage of <b>Trees::new_child</b>:<br>none</span></button></span><span class="plain">(</span><span class="reserved">tree_node</span><span class="plain"> *</span><span class="identifier">of</span><span class="plain">, </span><span class="reserved">tree_node_type</span><span class="plain"> *</span><span class="identifier">type</span><span class="plain">, </span><span class="reserved">general_pointer</span><span class="plain"> </span><span class="identifier">wrapping</span><span class="plain">) {</span>
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<span class="reserved">tree_node</span><span class="plain"> *</span><span class="identifier">N</span><span class="plain"> = </span><span class="functiontext"><a href="2-trs.html#SP4">Trees::new_node</a></span><span class="plain">(</span><span class="identifier">of</span><span class="plain">-></span><span class="element">owner</span><span class="plain">, </span><span class="identifier">type</span><span class="plain">, </span><span class="identifier">wrapping</span><span class="plain">);</span>
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<span class="functiontext"><a href="2-trs.html#SP11">Trees::make_child</a></span><span class="plain">(</span><span class="identifier">N</span><span class="plain">, </span><span class="identifier">of</span><span class="plain">);</span>
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<span class="reserved">return</span><span class="plain"> </span><span class="identifier">N</span><span class="plain">;</span>
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<span class="plain">}</span>
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</pre>
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<p class="inwebparagraph"></p>
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<p class="inwebparagraph"><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="display">
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<span class="reserved">typedef</span><span class="plain"> </span><span class="reserved">struct</span><span class="plain"> </span><span class="reserved">tree_type</span><span class="plain"> {</span>
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<span class="reserved">struct</span><span class="plain"> </span><span class="reserved">text_stream</span><span class="plain"> *</span><span class="identifier">name</span><span class="plain">;</span>
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<span class="reserved">int</span><span class="plain"> (*</span><span class="identifier">verify_root</span><span class="plain">)(</span><span class="reserved">struct</span><span class="plain"> </span><span class="reserved">tree_node</span><span class="plain"> *); </span><span class="comment"> function to vet the root node</span>
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<span class="constant">MEMORY_MANAGEMENT</span>
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<span class="plain">} </span><span class="reserved">tree_type</span><span class="plain">;</span>
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</pre>
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<p class="inwebparagraph"></p>
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<p class="endnote">The structure tree_type is private to this section.</p>
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<p class="inwebparagraph"><a id="SP7"></a><b>§7. </b></p>
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<pre class="display">
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<span class="reserved">tree_type</span><span class="plain"> *</span><span class="functiontext">Trees::new_type<button class="popup" onclick="togglePopup('usagePopup153')">...<span class="popuptext" id="usagePopup153">Usage of <b>Trees::new_type</b>:<br>none</span></button></span><span class="plain">(</span><span class="reserved">text_stream</span><span class="plain"> *</span><span class="identifier">name</span><span class="plain">, </span><span class="reserved">int</span><span class="plain"> (*</span><span class="identifier">verifier</span><span class="plain">)(</span><span class="reserved">tree_node</span><span class="plain"> *)) {</span>
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<span class="reserved">tree_type</span><span class="plain"> *</span><span class="identifier">T</span><span class="plain"> = </span><span class="identifier">CREATE</span><span class="plain">(</span><span class="reserved">tree_type</span><span class="plain">);</span>
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<span class="identifier">T</span><span class="plain">-></span><span class="element">name</span><span class="plain"> = </span><span class="functiontext"><a href="4-sm.html#SP3">Str::duplicate</a></span><span class="plain">(</span><span class="identifier">name</span><span class="plain">);</span>
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<span class="identifier">T</span><span class="plain">-></span><span class="element">verify_root</span><span class="plain"> = </span><span class="identifier">verifier</span><span class="plain">;</span>
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<span class="reserved">return</span><span class="plain"> </span><span class="identifier">T</span><span class="plain">;</span>
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<span class="plain">}</span>
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</pre>
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<p class="inwebparagraph"></p>
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<p class="inwebparagraph"><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 <code class="display"><span class="extract">verify_children</span></code>.
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</p>
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<pre class="display">
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<span class="reserved">typedef</span><span class="plain"> </span><span class="reserved">struct</span><span class="plain"> </span><span class="reserved">tree_node_type</span><span class="plain"> {</span>
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<span class="reserved">struct</span><span class="plain"> </span><span class="reserved">text_stream</span><span class="plain"> *</span><span class="identifier">node_type_name</span><span class="plain">; </span><span class="comment"> text such as <code class="display"><span class="extract">I"INVOCATION"</span></code></span>
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<span class="reserved">int</span><span class="plain"> </span><span class="identifier">required_MT</span><span class="plain">; </span><span class="comment"> if any; or negative for no restriction</span>
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<span class="reserved">int</span><span class="plain"> (*</span><span class="identifier">verify_children</span><span class="plain">)(</span><span class="reserved">struct</span><span class="plain"> </span><span class="reserved">tree_node</span><span class="plain"> *); </span><span class="comment"> function to vet the children</span>
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<span class="constant">MEMORY_MANAGEMENT</span>
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<span class="plain">} </span><span class="reserved">tree_node_type</span><span class="plain">;</span>
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</pre>
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<p class="inwebparagraph"></p>
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<p class="endnote">The structure tree_node_type is private to this section.</p>
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<p class="inwebparagraph"><a id="SP9"></a><b>§9. </b></p>
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<pre class="display">
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<span class="reserved">tree_node_type</span><span class="plain"> *</span><span class="functiontext">Trees::new_node_type<button class="popup" onclick="togglePopup('usagePopup154')">...<span class="popuptext" id="usagePopup154">Usage of <b>Trees::new_node_type</b>:<br>none</span></button></span><span class="plain">(</span><span class="reserved">text_stream</span><span class="plain"> *</span><span class="identifier">name</span><span class="plain">, </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">req</span><span class="plain">,</span>
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<span class="reserved">int</span><span class="plain"> (*</span><span class="identifier">verifier</span><span class="plain">)(</span><span class="reserved">tree_node</span><span class="plain"> *)) {</span>
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<span class="reserved">tree_node_type</span><span class="plain"> *</span><span class="identifier">NT</span><span class="plain"> = </span><span class="identifier">CREATE</span><span class="plain">(</span><span class="reserved">tree_node_type</span><span class="plain">);</span>
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<span class="identifier">NT</span><span class="plain">-></span><span class="element">node_type_name</span><span class="plain"> = </span><span class="functiontext"><a href="4-sm.html#SP3">Str::duplicate</a></span><span class="plain">(</span><span class="identifier">name</span><span class="plain">);</span>
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<span class="identifier">NT</span><span class="plain">-></span><span class="element">required_MT</span><span class="plain"> = </span><span class="identifier">req</span><span class="plain">;</span>
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<span class="identifier">NT</span><span class="plain">-></span><span class="element">verify_children</span><span class="plain"> = </span><span class="identifier">verifier</span><span class="plain">;</span>
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<span class="reserved">return</span><span class="plain"> </span><span class="identifier">NT</span><span class="plain">;</span>
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<span class="plain">}</span>
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</pre>
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<p class="inwebparagraph"></p>
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<p class="inwebparagraph"><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="display">
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<span class="reserved">void</span><span class="plain"> </span><span class="functiontext">Trees::make_root<button class="popup" onclick="togglePopup('usagePopup155')">...<span class="popuptext" id="usagePopup155">Usage of <b>Trees::make_root</b>:<br>none</span></button></span><span class="plain">(</span><span class="reserved">heterogeneous_tree</span><span class="plain"> *</span><span class="identifier">T</span><span class="plain">, </span><span class="reserved">tree_node</span><span class="plain"> *</span><span class="identifier">N</span><span class="plain">) {</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">T</span><span class="plain"> == </span><span class="identifier">NULL</span><span class="plain">) </span><span class="identifier">internal_error</span><span class="plain">(</span><span class="string">"no tree"</span><span class="plain">);</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">N</span><span class="plain"> == </span><span class="identifier">NULL</span><span class="plain">) </span><span class="identifier">internal_error</span><span class="plain">(</span><span class="string">"no node"</span><span class="plain">);</span>
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<span class="identifier">N</span><span class="plain">-></span><span class="element">owner</span><span class="plain"> = </span><span class="identifier">T</span><span class="plain">;</span>
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<span class="identifier">T</span><span class="plain">-></span><span class="element">root</span><span class="plain"> = </span><span class="identifier">N</span><span class="plain">;</span>
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<span class="identifier">N</span><span class="plain">-></span><span class="element">parent</span><span class="plain"> = </span><span class="identifier">NULL</span><span class="plain">;</span>
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<span class="identifier">N</span><span class="plain">-></span><span class="element">next</span><span class="plain"> = </span><span class="identifier">NULL</span><span class="plain">;</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">T</span><span class="plain">-></span><span class="element">type</span><span class="plain">-></span><span class="element">verify_root</span><span class="plain">)</span>
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<span class="reserved">if</span><span class="plain"> ((*(</span><span class="identifier">T</span><span class="plain">-></span><span class="identifier">type</span><span class="plain">-></span><span class="element">verify_root</span><span class="plain">))(</span><span class="identifier">N</span><span class="plain">) == </span><span class="constant">FALSE</span><span class="plain">)</span>
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<span class="identifier">internal_error</span><span class="plain">(</span><span class="string">"disallowed node as root"</span><span class="plain">);</span>
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<span class="plain">}</span>
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<span class="reserved">void</span><span class="plain"> </span><span class="functiontext">Trees::remove_root<button class="popup" onclick="togglePopup('usagePopup156')">...<span class="popuptext" id="usagePopup156">Usage of <b>Trees::remove_root</b>:<br><a href="2-trs.html#SP11">§11</a>, <a href="2-trs.html#SP12">§12</a></span></button></span><span class="plain">(</span><span class="reserved">heterogeneous_tree</span><span class="plain"> *</span><span class="identifier">T</span><span class="plain">) {</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">T</span><span class="plain"> == </span><span class="identifier">NULL</span><span class="plain">) </span><span class="identifier">internal_error</span><span class="plain">(</span><span class="string">"no tree"</span><span class="plain">);</span>
|
|
<span class="identifier">T</span><span class="plain">-></span><span class="element">root</span><span class="plain"> = </span><span class="identifier">NULL</span><span class="plain">;</span>
|
|
<span class="plain">}</span>
|
|
</pre>
|
|
|
|
<p class="inwebparagraph"></p>
|
|
|
|
<p class="inwebparagraph"><a id="SP11"></a><b>§11. </b>Otherwise, nodes are placed in a tree with respect to other nodes:
|
|
</p>
|
|
|
|
<pre class="display">
|
|
<span class="reserved">void</span><span class="plain"> </span><span class="functiontext">Trees::make_child<button class="popup" onclick="togglePopup('usagePopup157')">...<span class="popuptext" id="usagePopup157">Usage of <b>Trees::make_child</b>:<br><a href="2-trs.html#SP5">§5</a></span></button></span><span class="plain">(</span><span class="reserved">tree_node</span><span class="plain"> *</span><span class="identifier">N</span><span class="plain">, </span><span class="reserved">tree_node</span><span class="plain"> *</span><span class="identifier">of</span><span class="plain">) {</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">N</span><span class="plain"> == </span><span class="identifier">NULL</span><span class="plain">) </span><span class="identifier">internal_error</span><span class="plain">(</span><span class="string">"no node"</span><span class="plain">);</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">of</span><span class="plain"> == </span><span class="identifier">NULL</span><span class="plain">) </span><span class="identifier">internal_error</span><span class="plain">(</span><span class="string">"no node"</span><span class="plain">);</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">N</span><span class="plain"> == </span><span class="identifier">N</span><span class="plain">-></span><span class="element">owner</span><span class="plain">-></span><span class="element">root</span><span class="plain">) </span><span class="functiontext"><a href="2-trs.html#SP10">Trees::remove_root</a></span><span class="plain">(</span><span class="identifier">N</span><span class="plain">-></span><span class="element">owner</span><span class="plain">);</span>
|
|
<span class="identifier">N</span><span class="plain">-></span><span class="element">owner</span><span class="plain"> = </span><span class="identifier">of</span><span class="plain">-></span><span class="element">owner</span><span class="plain">;</span>
|
|
<span class="identifier">N</span><span class="plain">-></span><span class="element">parent</span><span class="plain"> = </span><span class="identifier">of</span><span class="plain">;</span>
|
|
<span class="identifier">N</span><span class="plain">-></span><span class="element">next</span><span class="plain"> = </span><span class="identifier">NULL</span><span class="plain">;</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">of</span><span class="plain">-></span><span class="element">child</span><span class="plain"> == </span><span class="identifier">NULL</span><span class="plain">)</span>
|
|
<span class="identifier">of</span><span class="plain">-></span><span class="element">child</span><span class="plain"> = </span><span class="identifier">N</span><span class="plain">;</span>
|
|
<span class="reserved">else</span>
|
|
<span class="reserved">for</span><span class="plain"> (</span><span class="reserved">tree_node</span><span class="plain"> *</span><span class="identifier">S</span><span class="plain"> = </span><span class="identifier">of</span><span class="plain">-></span><span class="element">child</span><span class="plain">; </span><span class="identifier">S</span><span class="plain">; </span><span class="identifier">S</span><span class="plain"> = </span><span class="identifier">S</span><span class="plain">-></span><span class="element">next</span><span class="plain">)</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">S</span><span class="plain">-></span><span class="element">next</span><span class="plain"> == </span><span class="identifier">NULL</span><span class="plain">) {</span>
|
|
<span class="identifier">S</span><span class="plain">-></span><span class="element">next</span><span class="plain"> = </span><span class="identifier">N</span><span class="plain">; </span><span class="reserved">break</span><span class="plain">;</span>
|
|
<span class="plain">}</span>
|
|
<span class="functiontext"><a href="2-trs.html#SP12">Trees::verify_children</a></span><span class="plain">(</span><span class="identifier">of</span><span class="plain">);</span>
|
|
<span class="plain">}</span>
|
|
|
|
<span class="reserved">void</span><span class="plain"> </span><span class="functiontext">Trees::make_eldest_child<button class="popup" onclick="togglePopup('usagePopup158')">...<span class="popuptext" id="usagePopup158">Usage of <b>Trees::make_eldest_child</b>:<br>none</span></button></span><span class="plain">(</span><span class="reserved">tree_node</span><span class="plain"> *</span><span class="identifier">N</span><span class="plain">, </span><span class="reserved">tree_node</span><span class="plain"> *</span><span class="identifier">of</span><span class="plain">) {</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">N</span><span class="plain"> == </span><span class="identifier">NULL</span><span class="plain">) </span><span class="identifier">internal_error</span><span class="plain">(</span><span class="string">"no node"</span><span class="plain">);</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">of</span><span class="plain"> == </span><span class="identifier">NULL</span><span class="plain">) </span><span class="identifier">internal_error</span><span class="plain">(</span><span class="string">"no node"</span><span class="plain">);</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">N</span><span class="plain"> == </span><span class="identifier">N</span><span class="plain">-></span><span class="element">owner</span><span class="plain">-></span><span class="element">root</span><span class="plain">) </span><span class="functiontext"><a href="2-trs.html#SP10">Trees::remove_root</a></span><span class="plain">(</span><span class="identifier">N</span><span class="plain">-></span><span class="element">owner</span><span class="plain">);</span>
|
|
<span class="identifier">N</span><span class="plain">-></span><span class="element">owner</span><span class="plain"> = </span><span class="identifier">of</span><span class="plain">-></span><span class="element">owner</span><span class="plain">;</span>
|
|
<span class="identifier">N</span><span class="plain">-></span><span class="element">parent</span><span class="plain"> = </span><span class="identifier">of</span><span class="plain">;</span>
|
|
<span class="identifier">N</span><span class="plain">-></span><span class="element">next</span><span class="plain"> = </span><span class="identifier">of</span><span class="plain">-></span><span class="element">child</span><span class="plain">;</span>
|
|
<span class="identifier">of</span><span class="plain">-></span><span class="element">child</span><span class="plain"> = </span><span class="identifier">N</span><span class="plain">;</span>
|
|
<span class="functiontext"><a href="2-trs.html#SP12">Trees::verify_children</a></span><span class="plain">(</span><span class="identifier">of</span><span class="plain">);</span>
|
|
<span class="plain">}</span>
|
|
|
|
<span class="reserved">void</span><span class="plain"> </span><span class="functiontext">Trees::make_sibling<button class="popup" onclick="togglePopup('usagePopup159')">...<span class="popuptext" id="usagePopup159">Usage of <b>Trees::make_sibling</b>:<br>none</span></button></span><span class="plain">(</span><span class="reserved">tree_node</span><span class="plain"> *</span><span class="identifier">N</span><span class="plain">, </span><span class="reserved">tree_node</span><span class="plain"> *</span><span class="identifier">of</span><span class="plain">) {</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">N</span><span class="plain"> == </span><span class="identifier">NULL</span><span class="plain">) </span><span class="identifier">internal_error</span><span class="plain">(</span><span class="string">"no node"</span><span class="plain">);</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">of</span><span class="plain"> == </span><span class="identifier">NULL</span><span class="plain">) </span><span class="identifier">internal_error</span><span class="plain">(</span><span class="string">"no node"</span><span class="plain">);</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">N</span><span class="plain"> == </span><span class="identifier">N</span><span class="plain">-></span><span class="element">owner</span><span class="plain">-></span><span class="element">root</span><span class="plain">) </span><span class="functiontext"><a href="2-trs.html#SP10">Trees::remove_root</a></span><span class="plain">(</span><span class="identifier">N</span><span class="plain">-></span><span class="element">owner</span><span class="plain">);</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">of</span><span class="plain"> == </span><span class="identifier">of</span><span class="plain">-></span><span class="element">owner</span><span class="plain">-></span><span class="element">root</span><span class="plain">)</span>
|
|
<span class="identifier">internal_error</span><span class="plain">(</span><span class="string">"nodes cannot be siblings of the root"</span><span class="plain">);</span>
|
|
<span class="identifier">N</span><span class="plain">-></span><span class="element">owner</span><span class="plain"> = </span><span class="identifier">of</span><span class="plain">-></span><span class="element">owner</span><span class="plain">;</span>
|
|
<span class="identifier">N</span><span class="plain">-></span><span class="element">parent</span><span class="plain"> = </span><span class="identifier">of</span><span class="plain">-></span><span class="element">parent</span><span class="plain">;</span>
|
|
<span class="identifier">N</span><span class="plain">-></span><span class="element">next</span><span class="plain"> = </span><span class="identifier">of</span><span class="plain">-></span><span class="element">next</span><span class="plain">;</span>
|
|
<span class="identifier">of</span><span class="plain">-></span><span class="element">next</span><span class="plain"> = </span><span class="identifier">N</span><span class="plain">;</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">of</span><span class="plain">-></span><span class="element">parent</span><span class="plain">) </span><span class="functiontext"><a href="2-trs.html#SP12">Trees::verify_children</a></span><span class="plain">(</span><span class="identifier">of</span><span class="plain">-></span><span class="element">parent</span><span class="plain">);</span>
|
|
<span class="plain">}</span>
|
|
</pre>
|
|
|
|
<p class="inwebparagraph"></p>
|
|
|
|
<p class="inwebparagraph"><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="display">
|
|
<span class="reserved">void</span><span class="plain"> </span><span class="functiontext">Trees::remove<button class="popup" onclick="togglePopup('usagePopup160')">...<span class="popuptext" id="usagePopup160">Usage of <b>Trees::remove</b>:<br>none</span></button></span><span class="plain">(</span><span class="reserved">tree_node</span><span class="plain"> *</span><span class="identifier">N</span><span class="plain">) {</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">N</span><span class="plain"> == </span><span class="identifier">NULL</span><span class="plain">) </span><span class="identifier">internal_error</span><span class="plain">(</span><span class="string">"no node"</span><span class="plain">);</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">N</span><span class="plain"> == </span><span class="identifier">N</span><span class="plain">-></span><span class="element">owner</span><span class="plain">-></span><span class="element">root</span><span class="plain">) { </span><span class="functiontext"><a href="2-trs.html#SP10">Trees::remove_root</a></span><span class="plain">(</span><span class="identifier">N</span><span class="plain">-></span><span class="element">owner</span><span class="plain">); </span><span class="reserved">return</span><span class="plain">; }</span>
|
|
<span class="reserved">tree_node</span><span class="plain"> *</span><span class="identifier">p</span><span class="plain"> = </span><span class="identifier">N</span><span class="plain">-></span><span class="element">parent</span><span class="plain">;</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">N</span><span class="plain">-></span><span class="element">parent</span><span class="plain">-></span><span class="element">child</span><span class="plain"> == </span><span class="identifier">N</span><span class="plain">)</span>
|
|
<span class="identifier">N</span><span class="plain">-></span><span class="element">parent</span><span class="plain">-></span><span class="identifier">child</span><span class="plain"> = </span><span class="identifier">N</span><span class="plain">-></span><span class="element">next</span><span class="plain">;</span>
|
|
<span class="reserved">else</span>
|
|
<span class="reserved">for</span><span class="plain"> (</span><span class="reserved">tree_node</span><span class="plain"> *</span><span class="identifier">S</span><span class="plain"> = </span><span class="identifier">N</span><span class="plain">-></span><span class="element">parent</span><span class="plain">-></span><span class="element">child</span><span class="plain">; </span><span class="identifier">S</span><span class="plain">; </span><span class="identifier">S</span><span class="plain"> = </span><span class="identifier">S</span><span class="plain">-></span><span class="element">next</span><span class="plain">)</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">S</span><span class="plain">-></span><span class="element">next</span><span class="plain"> == </span><span class="identifier">N</span><span class="plain">)</span>
|
|
<span class="identifier">S</span><span class="plain">-></span><span class="element">next</span><span class="plain"> = </span><span class="identifier">N</span><span class="plain">-></span><span class="element">next</span><span class="plain">;</span>
|
|
<span class="identifier">N</span><span class="plain">-></span><span class="element">parent</span><span class="plain"> = </span><span class="identifier">NULL</span><span class="plain">;</span>
|
|
<span class="identifier">N</span><span class="plain">-></span><span class="element">next</span><span class="plain"> = </span><span class="identifier">NULL</span><span class="plain">;</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">p</span><span class="plain">) </span><span class="functiontext"><a href="2-trs.html#SP12">Trees::verify_children</a></span><span class="plain">(</span><span class="identifier">p</span><span class="plain">);</span>
|
|
<span class="plain">}</span>
|
|
|
|
<span class="reserved">int</span><span class="plain"> </span><span class="functiontext">Trees::verify_children<button class="popup" onclick="togglePopup('usagePopup161')">...<span class="popuptext" id="usagePopup161">Usage of <b>Trees::verify_children</b>:<br><a href="2-trs.html#SP11">§11</a></span></button></span><span class="plain">(</span><span class="reserved">tree_node</span><span class="plain"> *</span><span class="identifier">N</span><span class="plain">) {</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">N</span><span class="plain"> == </span><span class="identifier">NULL</span><span class="plain">) </span><span class="identifier">internal_error</span><span class="plain">(</span><span class="string">"no node"</span><span class="plain">);</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">N</span><span class="plain">-></span><span class="element">type</span><span class="plain">-></span><span class="element">verify_children</span><span class="plain">)</span>
|
|
<span class="reserved">return</span><span class="plain"> (*(</span><span class="identifier">N</span><span class="plain">-></span><span class="element">type</span><span class="plain">-></span><span class="element">verify_children</span><span class="plain">))(</span><span class="identifier">N</span><span class="plain">);</span>
|
|
<span class="reserved">return</span><span class="plain"> </span><span class="constant">TRUE</span><span class="plain">;</span>
|
|
<span class="plain">}</span>
|
|
</pre>
|
|
|
|
<p class="inwebparagraph"></p>
|
|
|
|
<p class="inwebparagraph"><a id="SP13"></a><b>§13. Traversals. </b>These two functions allow us to traverse the tree, visiting each node along
|
|
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>
|
|
iterates from and then below the given node, but doesn't go through its siblings,
|
|
whereas <a href="2-trs.html#SP13" class="internal">Trees::traverse</a> does.
|
|
</p>
|
|
|
|
<p class="inwebparagraph">Note that it is legal to traverse the empty node, and does nothing.
|
|
</p>
|
|
|
|
<pre class="display">
|
|
<span class="reserved">void</span><span class="plain"> </span><span class="functiontext">Trees::traverse_tree<button class="popup" onclick="togglePopup('usagePopup162')">...<span class="popuptext" id="usagePopup162">Usage of <b>Trees::traverse_tree</b>:<br>none</span></button></span><span class="plain">(</span><span class="reserved">heterogeneous_tree</span><span class="plain"> *</span><span class="identifier">T</span><span class="plain">,</span>
|
|
<span class="reserved">void</span><span class="plain"> (*</span><span class="identifier">visitor</span><span class="plain">)(</span><span class="reserved">tree_node</span><span class="plain"> *, </span><span class="reserved">void</span><span class="plain"> *, </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">L</span><span class="plain">), </span><span class="reserved">void</span><span class="plain"> *</span><span class="identifier">state</span><span class="plain">) {</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">T</span><span class="plain"> == </span><span class="identifier">NULL</span><span class="plain">) </span><span class="identifier">internal_error</span><span class="plain">(</span><span class="string">"no tree"</span><span class="plain">);</span>
|
|
<span class="functiontext"><a href="2-trs.html#SP13">Trees::traverse_from</a></span><span class="plain">(</span><span class="identifier">T</span><span class="plain">-></span><span class="element">root</span><span class="plain">, </span><span class="identifier">visitor</span><span class="plain">, </span><span class="identifier">state</span><span class="plain">, </span><span class="constant">0</span><span class="plain">);</span>
|
|
<span class="plain">}</span>
|
|
|
|
<span class="reserved">void</span><span class="plain"> </span><span class="functiontext">Trees::traverse_from<button class="popup" onclick="togglePopup('usagePopup163')">...<span class="popuptext" id="usagePopup163">Usage of <b>Trees::traverse_from</b>:<br>none</span></button></span><span class="plain">(</span><span class="reserved">tree_node</span><span class="plain"> *</span><span class="identifier">N</span><span class="plain">,</span>
|
|
<span class="reserved">void</span><span class="plain"> (*</span><span class="identifier">visitor</span><span class="plain">)(</span><span class="reserved">tree_node</span><span class="plain"> *, </span><span class="reserved">void</span><span class="plain"> *, </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">L</span><span class="plain">), </span><span class="reserved">void</span><span class="plain"> *</span><span class="identifier">state</span><span class="plain">, </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">L</span><span class="plain">) {</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">N</span><span class="plain">) {</span>
|
|
<span class="plain">(*</span><span class="identifier">visitor</span><span class="plain">)(</span><span class="identifier">N</span><span class="plain">, </span><span class="identifier">state</span><span class="plain">, </span><span class="identifier">L</span><span class="plain">);</span>
|
|
<span class="functiontext"><a href="2-trs.html#SP13">Trees::traverse</a></span><span class="plain">(</span><span class="identifier">N</span><span class="plain">-></span><span class="element">child</span><span class="plain">, </span><span class="identifier">visitor</span><span class="plain">, </span><span class="identifier">state</span><span class="plain">, </span><span class="identifier">L</span><span class="plain">+1);</span>
|
|
<span class="plain">}</span>
|
|
<span class="plain">}</span>
|
|
|
|
<span class="reserved">void</span><span class="plain"> </span><span class="functiontext">Trees::traverse<button class="popup" onclick="togglePopup('usagePopup164')">...<span class="popuptext" id="usagePopup164">Usage of <b>Trees::traverse</b>:<br>none</span></button></span><span class="plain">(</span><span class="reserved">tree_node</span><span class="plain"> *</span><span class="identifier">N</span><span class="plain">,</span>
|
|
<span class="reserved">void</span><span class="plain"> (*</span><span class="identifier">visitor</span><span class="plain">)(</span><span class="reserved">tree_node</span><span class="plain"> *, </span><span class="reserved">void</span><span class="plain"> *, </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">L</span><span class="plain">), </span><span class="reserved">void</span><span class="plain"> *</span><span class="identifier">state</span><span class="plain">, </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">L</span><span class="plain">) {</span>
|
|
<span class="reserved">for</span><span class="plain"> (</span><span class="reserved">tree_node</span><span class="plain"> *</span><span class="identifier">M</span><span class="plain"> = </span><span class="identifier">N</span><span class="plain">; </span><span class="identifier">M</span><span class="plain">; </span><span class="identifier">M</span><span class="plain"> = </span><span class="identifier">M</span><span class="plain">-></span><span class="identifier">next</span><span class="plain">) {</span>
|
|
<span class="plain">(*</span><span class="identifier">visitor</span><span class="plain">)(</span><span class="identifier">M</span><span class="plain">, </span><span class="identifier">state</span><span class="plain">, </span><span class="identifier">L</span><span class="plain">);</span>
|
|
<span class="functiontext"><a href="2-trs.html#SP13">Trees::traverse</a></span><span class="plain">(</span><span class="identifier">M</span><span class="plain">-></span><span class="element">child</span><span class="plain">, </span><span class="identifier">visitor</span><span class="plain">, </span><span class="identifier">state</span><span class="plain">, </span><span class="identifier">L</span><span class="plain">+1);</span>
|
|
<span class="plain">}</span>
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<span class="plain">}</span>
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</pre>
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<p class="inwebparagraph"></p>
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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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