456 lines
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HTML
456 lines
61 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<title>Dictionaries</title>
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<body>
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<nav role="navigation">
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<h1><a href="../webs.html">Sources</a></h1>
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<ul>
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<li><a href="../inweb/index.html">inweb</a></li>
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</ul>
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<h2>Foundation</h2>
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<ul>
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<li><a href="../foundation-module/index.html">foundation-module</a></li>
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<li><a href="../foundation-test/index.html">foundation-test</a></li>
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<main role="main">
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<!--Weave of 'Dictionaries' generated by 7-->
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<ul class="crumbs"><li><a href="../webs.html">Source</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>Dictionaries</b></li></ul><p class="purpose">A simple implementation for a flexible-sized dictionary of key-value pairs.</p>
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<ul class="toc"><li><a href="#SP1">§1. Storage</a></li><li><a href="#SP2">§2. Creation</a></li><li><a href="#SP3">§3. Logging</a></li><li><a href="#SP4">§4. Hashing</a></li><li><a href="#SP5">§5. Create, find, destroy</a></li><li><a href="#SP8">§8. Accessing entries</a></li><li><a href="#SP11">§11. Disposal</a></li></ul><hr class="tocbar">
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<p class="inwebparagraph"><a id="SP1"></a><b>§1. Storage. </b>There's nothing fancy here. A "dictionary" is a hash table allowing reasonably
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efficient lookup: it's a correspondence between "keys", which are texts, and
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pointers to some external structure. Often these will also be texts, but
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not necessarily.
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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">dictionary</span><span class="plain"> {</span>
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<span class="reserved">int</span><span class="plain"> </span><span class="identifier">textual</span><span class="plain">; </span><span class="comment"> values are texts?</span>
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<span class="reserved">int</span><span class="plain"> </span><span class="identifier">no_entries</span><span class="plain">; </span><span class="comment"> total number of key-value pairs currently stored here</span>
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<span class="reserved">int</span><span class="plain"> </span><span class="identifier">hash_table_size</span><span class="plain">; </span><span class="comment"> size of array...</span>
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<span class="reserved">struct</span><span class="plain"> </span><span class="reserved">dict_entry</span><span class="plain"> *</span><span class="identifier">hash_table</span><span class="plain">; </span><span class="comment"> ...of linked lists of dictionary entries</span>
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<span class="constant">MEMORY_MANAGEMENT</span>
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<span class="plain">} </span><span class="reserved">dictionary</span><span class="plain">;</span>
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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">dict_entry</span><span class="plain"> {</span>
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<span class="reserved">int</span><span class="plain"> </span><span class="identifier">vacant</span><span class="plain">; </span><span class="comment"> a "vacant" entry is not currently used to store a k-v pair</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">key</span><span class="plain">; </span><span class="comment"> for non-vacant entries only: the key text</span>
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<span class="reserved">void</span><span class="plain"> *</span><span class="identifier">value</span><span class="plain">; </span><span class="comment"> for non-vacant entries only: the value, some kind of pointer</span>
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<span class="reserved">struct</span><span class="plain"> </span><span class="reserved">dict_entry</span><span class="plain"> *</span><span class="identifier">next_in_entry</span><span class="plain">;</span>
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<span class="plain">} </span><span class="reserved">dict_entry</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 dictionary is private to this section.</p>
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<p class="endnote">The structure dict_entry is accessed in 5/ee, 8/bdfw and here.</p>
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<p class="inwebparagraph"><a id="SP2"></a><b>§2. Creation. </b>Dictionaries can have arbitrary size, in that they expand as needed, but for
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efficiency's sake the caller can set them up with an initial size of her choice.
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</p>
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<pre class="display">
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<span class="reserved">dictionary</span><span class="plain"> *</span><span class="functiontext">Dictionaries::new</span><span class="plain">(</span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">S</span><span class="plain">, </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">textual</span><span class="plain">) {</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">S</span><span class="plain"> < </span><span class="constant">2</span><span class="plain">) </span><span class="identifier">internal_error</span><span class="plain">(</span><span class="string">"dictionary too small"</span><span class="plain">);</span>
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<span class="reserved">dictionary</span><span class="plain"> *</span><span class="identifier">D</span><span class="plain"> = </span><span class="identifier">CREATE</span><span class="plain">(</span><span class="reserved">dictionary</span><span class="plain">);</span>
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<span class="identifier">D</span><span class="plain">-></span><span class="element">textual</span><span class="plain"> = </span><span class="identifier">textual</span><span class="plain">;</span>
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<span class="identifier">D</span><span class="plain">-></span><span class="element">hash_table_size</span><span class="plain"> = </span><span class="identifier">S</span><span class="plain">;</span>
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<span class="identifier">D</span><span class="plain">-></span><span class="element">no_entries</span><span class="plain"> = </span><span class="constant">0</span><span class="plain">;</span>
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<span class="identifier">D</span><span class="plain">-></span><span class="element">hash_table</span><span class="plain"> = </span><span class="functiontext">Memory::I7_calloc</span><span class="plain">(</span><span class="identifier">S</span><span class="plain">, </span><span class="reserved">sizeof</span><span class="plain">(</span><span class="reserved">dict_entry</span><span class="plain">), </span><span class="constant">DICTIONARY_MREASON</span><span class="plain">);</span>
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<span class="reserved">for</span><span class="plain"> (</span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">i</span><span class="plain">=0; </span><span class="identifier">i</span><span class="plain"><</span><span class="identifier">S</span><span class="plain">; </span><span class="identifier">i</span><span class="plain">++) {</span>
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<span class="identifier">D</span><span class="plain">-></span><span class="element">hash_table</span><span class="plain">[</span><span class="identifier">i</span><span class="plain">].</span><span class="element">vacant</span><span class="plain"> = </span><span class="constant">TRUE</span><span class="plain">;</span>
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<span class="identifier">D</span><span class="plain">-></span><span class="element">hash_table</span><span class="plain">[</span><span class="identifier">i</span><span class="plain">].</span><span class="element">value</span><span class="plain"> = </span><span class="identifier">NULL</span><span class="plain">;</span>
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<span class="identifier">D</span><span class="plain">-></span><span class="element">hash_table</span><span class="plain">[</span><span class="identifier">i</span><span class="plain">].</span><span class="element">next_in_entry</span><span class="plain"> = </span><span class="identifier">NULL</span><span class="plain">;</span>
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<span class="plain">}</span>
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<span class="reserved">return</span><span class="plain"> </span><span class="identifier">D</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="endnote">The function Dictionaries::new is used in <a href="#SP7_2">§7.2</a>, 3/cla (<a href="3-cla.html#SP5">§5</a>), 4/sm (<a href="4-sm.html#SP26_1">§26.1</a>).</p>
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<p class="inwebparagraph"><a id="SP3"></a><b>§3. Logging. </b></p>
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<pre class="display">
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<span class="reserved">void</span><span class="plain"> </span><span class="functiontext">Dictionaries::log</span><span class="plain">(</span><span class="constant">OUTPUT_STREAM</span><span class="plain">, </span><span class="reserved">dictionary</span><span class="plain"> *</span><span class="identifier">D</span><span class="plain">) {</span>
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<span class="identifier">WRITE</span><span class="plain">(</span><span class="string">"Dictionary:\n"</span><span class="plain">, (</span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain">) </span><span class="identifier">D</span><span class="plain">); </span><span class="constant">INDENT</span><span class="plain">;</span>
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<span class="reserved">for</span><span class="plain"> (</span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">i</span><span class="plain">=0; </span><span class="identifier">i</span><span class="plain"><</span><span class="identifier">D</span><span class="plain">-></span><span class="element">hash_table_size</span><span class="plain">; </span><span class="identifier">i</span><span class="plain">++) {</span>
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<span class="identifier">WRITE</span><span class="plain">(</span><span class="string">"Slot %02d:"</span><span class="plain">, </span><span class="identifier">i</span><span class="plain">);</span>
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<span class="reserved">for</span><span class="plain"> (</span><span class="reserved">dict_entry</span><span class="plain"> *</span><span class="identifier">E</span><span class="plain"> = &(</span><span class="identifier">D</span><span class="plain">-></span><span class="element">hash_table</span><span class="plain">[</span><span class="identifier">i</span><span class="plain">]); </span><span class="identifier">E</span><span class="plain">; </span><span class="identifier">E</span><span class="plain"> = </span><span class="identifier">E</span><span class="plain">-></span><span class="element">next_in_entry</span><span class="plain">)</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">E</span><span class="plain">-></span><span class="element">vacant</span><span class="plain">) </span><span class="identifier">WRITE</span><span class="plain">(</span><span class="string">" vacant"</span><span class="plain">);</span>
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<span class="reserved">else</span><span class="plain"> </span><span class="reserved">if</span><span class="plain"> (</span><span class="identifier">D</span><span class="plain">-></span><span class="element">textual</span><span class="plain">) </span><span class="identifier">WRITE</span><span class="plain">(</span><span class="string">" %S='%S'"</span><span class="plain">, </span><span class="identifier">E</span><span class="plain">-></span><span class="element">key</span><span class="plain">, </span><span class="identifier">E</span><span class="plain">-></span><span class="element">value</span><span class="plain">);</span>
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<span class="reserved">else</span><span class="plain"> </span><span class="identifier">WRITE</span><span class="plain">(</span><span class="string">" %S=%08x"</span><span class="plain">, </span><span class="identifier">E</span><span class="plain">-></span><span class="element">key</span><span class="plain">, (</span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain">) </span><span class="identifier">E</span><span class="plain">-></span><span class="element">value</span><span class="plain">);</span>
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<span class="identifier">WRITE</span><span class="plain">(</span><span class="string">"\n"</span><span class="plain">);</span>
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<span class="plain">}</span>
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<span class="constant">OUTDENT</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="endnote">The function Dictionaries::log appears nowhere else.</p>
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<p class="inwebparagraph"><a id="SP4"></a><b>§4. Hashing. </b>The whole point of a hash table is that it crudely sorts the contents by a rough
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indication of the key values. This crude indication is the hash value, calculated
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here. If there are <code class="display"><span class="extract">N</span></code> slots in the dictionary table, this tells us which slot
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(from 0 to <code class="display"><span class="extract">N-1</span></code>) a given key value belongs in.
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</p>
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<pre class="display">
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<span class="reserved">int</span><span class="plain"> </span><span class="functiontext">Dictionaries::hash</span><span class="plain">(</span><span class="reserved">text_stream</span><span class="plain"> *</span><span class="identifier">K</span><span class="plain">, </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">N</span><span class="plain">) {</span>
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<span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">hash</span><span class="plain"> = </span><span class="constant">0</span><span class="plain">;</span>
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<span class="identifier">LOOP_THROUGH_TEXT</span><span class="plain">(</span><span class="identifier">P</span><span class="plain">, </span><span class="identifier">K</span><span class="plain">)</span>
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<span class="identifier">hash</span><span class="plain"> = </span><span class="constant">16339</span><span class="plain">*</span><span class="identifier">hash</span><span class="plain"> + ((</span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain">) </span><span class="functiontext">Str::get</span><span class="plain">(</span><span class="identifier">P</span><span class="plain">));</span>
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<span class="reserved">return</span><span class="plain"> (</span><span class="reserved">int</span><span class="plain">) (</span><span class="identifier">hash</span><span class="plain"> % ((</span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</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="endnote">The function Dictionaries::hash is used in <a href="#SP7_3">§7.3</a>.</p>
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<p class="inwebparagraph"><a id="SP5"></a><b>§5. Create, find, destroy. </b>These three fundamental operations locate the dictionary entry structure for
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a given key value, and then do something to/with it. Note that these pointers
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remain valid only until somebody writes a new value into the dictionary;
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so be careful if thread safety's an issue.
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</p>
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<pre class="display">
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<span class="reserved">dict_entry</span><span class="plain"> *</span><span class="functiontext">Dictionaries::find</span><span class="plain">(</span><span class="reserved">dictionary</span><span class="plain"> *</span><span class="identifier">D</span><span class="plain">, </span><span class="reserved">text_stream</span><span class="plain"> *</span><span class="identifier">K</span><span class="plain">) {</span>
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<span class="reserved">return</span><span class="plain"> </span><span class="functiontext">Dictionaries::find_p</span><span class="plain">(</span><span class="identifier">D</span><span class="plain">, </span><span class="identifier">K</span><span class="plain">, </span><span class="constant">0</span><span class="plain">);</span>
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<span class="plain">}</span>
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<span class="reserved">dict_entry</span><span class="plain"> *</span><span class="functiontext">Dictionaries::create</span><span class="plain">(</span><span class="reserved">dictionary</span><span class="plain"> *</span><span class="identifier">D</span><span class="plain">, </span><span class="reserved">text_stream</span><span class="plain"> *</span><span class="identifier">K</span><span class="plain">) {</span>
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<span class="reserved">return</span><span class="plain"> </span><span class="functiontext">Dictionaries::find_p</span><span class="plain">(</span><span class="identifier">D</span><span class="plain">, </span><span class="identifier">K</span><span class="plain">, </span><span class="constant">1</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">Dictionaries::destroy</span><span class="plain">(</span><span class="reserved">dictionary</span><span class="plain"> *</span><span class="identifier">D</span><span class="plain">, </span><span class="reserved">text_stream</span><span class="plain"> *</span><span class="identifier">K</span><span class="plain">) {</span>
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<span class="functiontext">Dictionaries::find_p</span><span class="plain">(</span><span class="identifier">D</span><span class="plain">, </span><span class="identifier">K</span><span class="plain">, -1);</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="endnote">The function Dictionaries::find is used in <a href="#SP6">§6</a>, <a href="#SP8">§8</a>, <a href="#SP10">§10</a>, 3/cla (<a href="3-cla.html#SP13">§13</a>).</p>
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<p class="endnote">The function Dictionaries::create is used in <a href="#SP6">§6</a>, <a href="#SP9">§9</a>, 3/cla (<a href="3-cla.html#SP5">§5</a>).</p>
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<p class="endnote">The function Dictionaries::destroy is used in <a href="#SP6">§6</a>.</p>
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<p class="inwebparagraph"><a id="SP6"></a><b>§6. </b>A nuisance we have to live with is that we often want to express the key
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as wide text (so that we can use literals like <code class="display"><span class="extract">L"my-key"</span></code>) instead of text
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streams. So we also offer versions suffixed <code class="display"><span class="extract">_literal</span></code>:
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</p>
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<pre class="display">
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<span class="reserved">dict_entry</span><span class="plain"> *</span><span class="functiontext">Dictionaries::find_literal</span><span class="plain">(</span><span class="reserved">dictionary</span><span class="plain"> *</span><span class="identifier">D</span><span class="plain">, </span><span class="identifier">wchar_t</span><span class="plain"> *</span><span class="identifier">lit</span><span class="plain">) {</span>
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<span class="identifier">TEMPORARY_TEXT</span><span class="plain">(</span><span class="identifier">K</span><span class="plain">);</span>
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<span class="identifier">WRITE_TO</span><span class="plain">(</span><span class="identifier">K</span><span class="plain">, </span><span class="string">"%w"</span><span class="plain">, </span><span class="identifier">lit</span><span class="plain">);</span>
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<span class="reserved">dict_entry</span><span class="plain"> *</span><span class="identifier">E</span><span class="plain"> = </span><span class="functiontext">Dictionaries::find</span><span class="plain">(</span><span class="identifier">D</span><span class="plain">, </span><span class="identifier">K</span><span class="plain">);</span>
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<span class="identifier">DISCARD_TEXT</span><span class="plain">(</span><span class="identifier">K</span><span class="plain">);</span>
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<span class="reserved">return</span><span class="plain"> </span><span class="identifier">E</span><span class="plain">;</span>
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<span class="plain">}</span>
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<span class="reserved">dict_entry</span><span class="plain"> *</span><span class="functiontext">Dictionaries::create_literal</span><span class="plain">(</span><span class="reserved">dictionary</span><span class="plain"> *</span><span class="identifier">D</span><span class="plain">, </span><span class="identifier">wchar_t</span><span class="plain"> *</span><span class="identifier">lit</span><span class="plain">) {</span>
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<span class="identifier">TEMPORARY_TEXT</span><span class="plain">(</span><span class="identifier">K</span><span class="plain">);</span>
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<span class="identifier">WRITE_TO</span><span class="plain">(</span><span class="identifier">K</span><span class="plain">, </span><span class="string">"%w"</span><span class="plain">, </span><span class="identifier">lit</span><span class="plain">);</span>
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<span class="reserved">dict_entry</span><span class="plain"> *</span><span class="identifier">E</span><span class="plain"> = </span><span class="functiontext">Dictionaries::create</span><span class="plain">(</span><span class="identifier">D</span><span class="plain">, </span><span class="identifier">K</span><span class="plain">);</span>
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<span class="identifier">DISCARD_TEXT</span><span class="plain">(</span><span class="identifier">K</span><span class="plain">);</span>
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<span class="reserved">return</span><span class="plain"> </span><span class="identifier">E</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">Dictionaries::destroy_literal</span><span class="plain">(</span><span class="reserved">dictionary</span><span class="plain"> *</span><span class="identifier">D</span><span class="plain">, </span><span class="identifier">wchar_t</span><span class="plain"> *</span><span class="identifier">lit</span><span class="plain">) {</span>
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<span class="identifier">TEMPORARY_TEXT</span><span class="plain">(</span><span class="identifier">K</span><span class="plain">);</span>
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<span class="identifier">WRITE_TO</span><span class="plain">(</span><span class="identifier">K</span><span class="plain">, </span><span class="string">"%w"</span><span class="plain">, </span><span class="identifier">lit</span><span class="plain">);</span>
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<span class="functiontext">Dictionaries::destroy</span><span class="plain">(</span><span class="identifier">D</span><span class="plain">, </span><span class="identifier">K</span><span class="plain">);</span>
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<span class="identifier">DISCARD_TEXT</span><span class="plain">(</span><span class="identifier">K</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="endnote">The function Dictionaries::find_literal is used in <a href="#SP8">§8</a>, <a href="#SP10">§10</a>.</p>
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<p class="endnote">The function Dictionaries::create_literal is used in <a href="#SP9">§9</a>, 4/sm (<a href="4-sm.html#SP26_1">§26.1</a>).</p>
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<p class="endnote">The function Dictionaries::destroy_literal appears nowhere else.</p>
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<p class="inwebparagraph"><a id="SP7"></a><b>§7. </b>So, then, find an entry (if <code class="display"><span class="extract">change</span></code> is <code class="display"><span class="extract">0</span></code>), create it (if <code class="display"><span class="extract">+1</span></code>) or delete
|
|
it (if <code class="display"><span class="extract">-1</span></code>).
|
|
</p>
|
|
|
|
<pre class="display">
|
|
<span class="reserved">dict_entry</span><span class="plain"> *</span><span class="functiontext">Dictionaries::find_p</span><span class="plain">(</span><span class="reserved">dictionary</span><span class="plain"> *</span><span class="identifier">D</span><span class="plain">, </span><span class="reserved">text_stream</span><span class="plain"> *</span><span class="identifier">K</span><span class="plain">, </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">change</span><span class="plain">) {</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">D</span><span class="plain"> == </span><span class="identifier">NULL</span><span class="plain">) </span><<span class="cwebmacro">Handle the null dictionary</span> <span class="cwebmacronumber">7.1</span>><span class="plain">;</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">change</span><span class="plain"> == </span><span class="constant">1</span><span class="plain">) </span><<span class="cwebmacro">Expand the dictionary if necessary</span> <span class="cwebmacronumber">7.2</span>><span class="plain">;</span>
|
|
<<span class="cwebmacro">Work within the existing dictionary</span> <span class="cwebmacronumber">7.3</span>><span class="plain">;</span>
|
|
<span class="plain">}</span>
|
|
</pre>
|
|
|
|
<p class="inwebparagraph"></p>
|
|
|
|
<p class="endnote">The function Dictionaries::find_p is used in <a href="#SP5">§5</a>, <a href="#SP7_2">§7.2</a>.</p>
|
|
|
|
<p class="inwebparagraph"><a id="SP7_1"></a><b>§7.1. </b>It's legal to perform a find on the null dictionary: the answer's always "no".
|
|
</p>
|
|
|
|
|
|
<p class="macrodefinition"><code class="display">
|
|
<<span class="cwebmacrodefn">Handle the null dictionary</span> <span class="cwebmacronumber">7.1</span>> =
|
|
</code></p>
|
|
|
|
|
|
<pre class="displaydefn">
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">change</span><span class="plain"> == </span><span class="constant">0</span><span class="plain">) </span><span class="reserved">return</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">"tried to create or destroy in a null dictionary"</span><span class="plain">);</span>
|
|
</pre>
|
|
|
|
<p class="inwebparagraph"></p>
|
|
|
|
<p class="endnote">This code is used in <a href="#SP7">§7</a>.</p>
|
|
|
|
<p class="inwebparagraph"><a id="SP7_2"></a><b>§7.2. </b>For speed, our policy is that the hash table should have roughly the
|
|
same number of slots as there are entries in the dictionary; that way, each
|
|
slot will have an average of one or fewer entries. When we exceed this
|
|
ideal population, we double the dictionary's capacity.
|
|
</p>
|
|
|
|
|
|
<p class="macrodefinition"><code class="display">
|
|
<<span class="cwebmacrodefn">Expand the dictionary if necessary</span> <span class="cwebmacronumber">7.2</span>> =
|
|
</code></p>
|
|
|
|
|
|
<pre class="displaydefn">
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">D</span><span class="plain">-></span><span class="element">no_entries</span><span class="plain"> > </span><span class="identifier">D</span><span class="plain">-></span><span class="element">hash_table_size</span><span class="plain">) {</span>
|
|
<span class="reserved">dictionary</span><span class="plain"> *</span><span class="identifier">D2</span><span class="plain"> = </span><span class="functiontext">Dictionaries::new</span><span class="plain">(2*</span><span class="identifier">D</span><span class="plain">-></span><span class="element">hash_table_size</span><span class="plain">, </span><span class="identifier">D</span><span class="plain">-></span><span class="element">textual</span><span class="plain">);</span>
|
|
<span class="reserved">for</span><span class="plain"> (</span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">i</span><span class="plain">=0; </span><span class="identifier">i</span><span class="plain"><</span><span class="identifier">D</span><span class="plain">-></span><span class="element">hash_table_size</span><span class="plain">; </span><span class="identifier">i</span><span class="plain">++)</span>
|
|
<span class="reserved">for</span><span class="plain"> (</span><span class="reserved">dict_entry</span><span class="plain"> *</span><span class="identifier">E</span><span class="plain"> = &(</span><span class="identifier">D</span><span class="plain">-></span><span class="element">hash_table</span><span class="plain">[</span><span class="identifier">i</span><span class="plain">]); </span><span class="identifier">E</span><span class="plain">; </span><span class="identifier">E</span><span class="plain"> = </span><span class="identifier">E</span><span class="plain">-></span><span class="element">next_in_entry</span><span class="plain">)</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">E</span><span class="plain">-></span><span class="element">vacant</span><span class="plain"> == </span><span class="constant">FALSE</span><span class="plain">) {</span>
|
|
<span class="reserved">dict_entry</span><span class="plain"> *</span><span class="identifier">E2</span><span class="plain"> = </span><span class="functiontext">Dictionaries::find_p</span><span class="plain">(</span><span class="identifier">D2</span><span class="plain">, </span><span class="identifier">E</span><span class="plain">-></span><span class="element">key</span><span class="plain">, </span><span class="constant">1</span><span class="plain">);</span>
|
|
<span class="identifier">E2</span><span class="plain">-></span><span class="element">value</span><span class="plain"> = </span><span class="identifier">E</span><span class="plain">-></span><span class="element">value</span><span class="plain">;</span>
|
|
<span class="plain">}</span>
|
|
<span class="functiontext">Memory::I7_free</span><span class="plain">(</span><span class="identifier">D</span><span class="plain">-></span><span class="element">hash_table</span><span class="plain">, </span><span class="constant">DICTIONARY_MREASON</span><span class="plain">,</span>
|
|
<span class="identifier">D</span><span class="plain">-></span><span class="element">hash_table_size</span><span class="plain">*((</span><span class="reserved">int</span><span class="plain">) </span><span class="reserved">sizeof</span><span class="plain">(</span><span class="reserved">dict_entry</span><span class="plain">)));</span>
|
|
<span class="identifier">D</span><span class="plain">-></span><span class="element">hash_table_size</span><span class="plain"> = </span><span class="identifier">D2</span><span class="plain">-></span><span class="element">hash_table_size</span><span class="plain">;</span>
|
|
<span class="identifier">D</span><span class="plain">-></span><span class="element">hash_table</span><span class="plain"> = </span><span class="identifier">D2</span><span class="plain">-></span><span class="element">hash_table</span><span class="plain">;</span>
|
|
<span class="plain">}</span>
|
|
</pre>
|
|
|
|
<p class="inwebparagraph"></p>
|
|
|
|
<p class="endnote">This code is used in <a href="#SP7">§7</a>.</p>
|
|
|
|
<p class="inwebparagraph"><a id="SP7_3"></a><b>§7.3. </b><code class="display">
|
|
<<span class="cwebmacrodefn">Work within the existing dictionary</span> <span class="cwebmacronumber">7.3</span>> =
|
|
</code></p>
|
|
|
|
|
|
<pre class="displaydefn">
|
|
<span class="reserved">dict_entry</span><span class="plain"> *</span><span class="identifier">last_E</span><span class="plain"> = </span><span class="identifier">NULL</span><span class="plain">;</span>
|
|
<span class="reserved">for</span><span class="plain"> (</span><span class="reserved">dict_entry</span><span class="plain"> *</span><span class="identifier">E</span><span class="plain"> = &(</span><span class="identifier">D</span><span class="plain">-></span><span class="element">hash_table</span><span class="plain">[</span><span class="functiontext">Dictionaries::hash</span><span class="plain">(</span><span class="identifier">K</span><span class="plain">, </span><span class="identifier">D</span><span class="plain">-></span><span class="element">hash_table_size</span><span class="plain">)]);</span>
|
|
<span class="identifier">E</span><span class="plain">; </span><span class="identifier">E</span><span class="plain"> = </span><span class="identifier">E</span><span class="plain">-></span><span class="identifier">next_in_entry</span><span class="plain">) {</span>
|
|
<span class="identifier">last_E</span><span class="plain"> = </span><span class="identifier">E</span><span class="plain">;</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">E</span><span class="plain">-></span><span class="element">vacant</span><span class="plain">) {</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">change</span><span class="plain"> == </span><span class="constant">1</span><span class="plain">) { </span><<span class="cwebmacro">Make E the new entry</span> <span class="cwebmacronumber">7.3.1</span>><span class="plain">; </span><span class="reserved">return</span><span class="plain"> </span><span class="identifier">E</span><span class="plain">; }</span>
|
|
<span class="plain">} </span><span class="reserved">else</span><span class="plain"> {</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="functiontext">Str::eq</span><span class="plain">(</span><span class="identifier">K</span><span class="plain">, </span><span class="identifier">E</span><span class="plain">-></span><span class="element">key</span><span class="plain">)) {</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">change</span><span class="plain"> == -1) </span><<span class="cwebmacro">Destroy the E entry</span> <span class="cwebmacronumber">7.3.2</span>><span class="plain">;</span>
|
|
<span class="reserved">return</span><span class="plain"> </span><span class="identifier">E</span><span class="plain">;</span>
|
|
<span class="plain">}</span>
|
|
<span class="plain">}</span>
|
|
<span class="plain">}</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">change</span><span class="plain"> == </span><span class="constant">1</span><span class="plain">) {</span>
|
|
<span class="reserved">dict_entry</span><span class="plain"> *</span><span class="identifier">E</span><span class="plain"> = </span><span class="identifier">CREATE</span><span class="plain">(</span><span class="reserved">dict_entry</span><span class="plain">);</span>
|
|
<<span class="cwebmacro">Make E the new entry</span> <span class="cwebmacronumber">7.3.1</span>><span class="plain">;</span>
|
|
<span class="identifier">last_E</span><span class="plain">-></span><span class="element">next_in_entry</span><span class="plain"> = </span><span class="identifier">E</span><span class="plain">;</span>
|
|
<span class="reserved">return</span><span class="plain"> </span><span class="identifier">E</span><span class="plain">;</span>
|
|
<span class="plain">}</span>
|
|
<span class="reserved">return</span><span class="plain"> </span><span class="identifier">NULL</span><span class="plain">;</span>
|
|
</pre>
|
|
|
|
<p class="inwebparagraph"></p>
|
|
|
|
<p class="endnote">This code is used in <a href="#SP7">§7</a>.</p>
|
|
|
|
<p class="inwebparagraph"><a id="SP7_3_1"></a><b>§7.3.1. </b>When creating text values, we want them to be empty strings rather than null
|
|
strings, so that printing to them will work.
|
|
</p>
|
|
|
|
|
|
<p class="macrodefinition"><code class="display">
|
|
<<span class="cwebmacrodefn">Make E the new entry</span> <span class="cwebmacronumber">7.3.1</span>> =
|
|
</code></p>
|
|
|
|
|
|
<pre class="displaydefn">
|
|
<span class="identifier">E</span><span class="plain">-></span><span class="element">vacant</span><span class="plain"> = </span><span class="constant">FALSE</span><span class="plain">;</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">D</span><span class="plain">-></span><span class="element">textual</span><span class="plain">) </span><span class="identifier">E</span><span class="plain">-></span><span class="element">value</span><span class="plain"> = </span><span class="functiontext">Str::new</span><span class="plain">(); </span><span class="reserved">else</span><span class="plain"> </span><span class="identifier">E</span><span class="plain">-></span><span class="element">value</span><span class="plain"> = </span><span class="identifier">NULL</span><span class="plain">;</span>
|
|
<span class="identifier">E</span><span class="plain">-></span><span class="element">key</span><span class="plain"> = </span><span class="functiontext">Str::duplicate</span><span class="plain">(</span><span class="identifier">K</span><span class="plain">);</span>
|
|
<span class="identifier">D</span><span class="plain">-></span><span class="element">no_entries</span><span class="plain">++;</span>
|
|
</pre>
|
|
|
|
<p class="inwebparagraph"></p>
|
|
|
|
<p class="endnote">This code is used in <a href="#SP7_3">§7.3</a> (twice).</p>
|
|
|
|
<p class="inwebparagraph"><a id="SP7_3_2"></a><b>§7.3.2. </b>When deleting text values, we close them first, to give back the memory.
|
|
Careful: it would not be thread-safe to allow different threads to use the
|
|
same dictionary if deletions are a possibility.
|
|
</p>
|
|
|
|
|
|
<p class="macrodefinition"><code class="display">
|
|
<<span class="cwebmacrodefn">Destroy the E entry</span> <span class="cwebmacronumber">7.3.2</span>> =
|
|
</code></p>
|
|
|
|
|
|
<pre class="displaydefn">
|
|
<span class="identifier">E</span><span class="plain">-></span><span class="element">vacant</span><span class="plain"> = </span><span class="constant">TRUE</span><span class="plain">; </span><span class="identifier">D</span><span class="plain">-></span><span class="element">no_entries</span><span class="plain">--;</span>
|
|
<span class="reserved">if</span><span class="plain"> ((</span><span class="identifier">D</span><span class="plain">-></span><span class="element">textual</span><span class="plain">) && (</span><span class="identifier">E</span><span class="plain">-></span><span class="element">value</span><span class="plain">)) </span><span class="functiontext">Str::dispose_of</span><span class="plain">(</span><span class="identifier">E</span><span class="plain">-></span><span class="element">value</span><span class="plain">);</span>
|
|
<span class="identifier">E</span><span class="plain">-></span><span class="element">value</span><span class="plain"> = </span><span class="identifier">NULL</span><span class="plain">;</span>
|
|
</pre>
|
|
|
|
<p class="inwebparagraph"></p>
|
|
|
|
<p class="endnote">This code is used in <a href="#SP7_3">§7.3</a>.</p>
|
|
|
|
<p class="inwebparagraph"><a id="SP8"></a><b>§8. Accessing entries. </b>Eventually we're going to want the value. In principle we could be storing
|
|
values which are arbitrary pointers, so we have to use void pointers:
|
|
</p>
|
|
|
|
<pre class="display">
|
|
<span class="reserved">void</span><span class="plain"> *</span><span class="functiontext">Dictionaries::read_value</span><span class="plain">(</span><span class="reserved">dictionary</span><span class="plain"> *</span><span class="identifier">D</span><span class="plain">, </span><span class="reserved">text_stream</span><span class="plain"> *</span><span class="identifier">key</span><span class="plain">) {</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">D</span><span class="plain"> == </span><span class="identifier">NULL</span><span class="plain">) </span><span class="reserved">return</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">D</span><span class="plain">-></span><span class="element">textual</span><span class="plain">) </span><span class="identifier">internal_error</span><span class="plain">(</span><span class="string">"textual dictionary accessed as pointy"</span><span class="plain">);</span>
|
|
<span class="reserved">dict_entry</span><span class="plain"> *</span><span class="identifier">E</span><span class="plain"> = </span><span class="functiontext">Dictionaries::find</span><span class="plain">(</span><span class="identifier">D</span><span class="plain">, </span><span class="identifier">key</span><span class="plain">);</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">E</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">"read null dictionary entry"</span><span class="plain">);</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">E</span><span class="plain">-></span><span class="element">vacant</span><span class="plain">) </span><span class="identifier">internal_error</span><span class="plain">(</span><span class="string">"read vacant dictionary entry"</span><span class="plain">);</span>
|
|
<span class="reserved">return</span><span class="plain"> </span><span class="identifier">E</span><span class="plain">-></span><span class="identifier">value</span><span class="plain">;</span>
|
|
<span class="plain">}</span>
|
|
<span class="reserved">void</span><span class="plain"> *</span><span class="functiontext">Dictionaries::read_value_literal</span><span class="plain">(</span><span class="reserved">dictionary</span><span class="plain"> *</span><span class="identifier">D</span><span class="plain">, </span><span class="identifier">wchar_t</span><span class="plain"> *</span><span class="identifier">key</span><span class="plain">) {</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">D</span><span class="plain"> == </span><span class="identifier">NULL</span><span class="plain">) </span><span class="reserved">return</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">D</span><span class="plain">-></span><span class="element">textual</span><span class="plain">) </span><span class="identifier">internal_error</span><span class="plain">(</span><span class="string">"textual dictionary accessed as pointy"</span><span class="plain">);</span>
|
|
<span class="reserved">dict_entry</span><span class="plain"> *</span><span class="identifier">E</span><span class="plain"> = </span><span class="functiontext">Dictionaries::find_literal</span><span class="plain">(</span><span class="identifier">D</span><span class="plain">, </span><span class="identifier">key</span><span class="plain">);</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">E</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">"read null dictionary entry"</span><span class="plain">);</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">E</span><span class="plain">-></span><span class="element">vacant</span><span class="plain">) </span><span class="identifier">internal_error</span><span class="plain">(</span><span class="string">"read vacant dictionary entry"</span><span class="plain">);</span>
|
|
<span class="reserved">return</span><span class="plain"> </span><span class="identifier">E</span><span class="plain">-></span><span class="identifier">value</span><span class="plain">;</span>
|
|
<span class="plain">}</span>
|
|
|
|
<span class="reserved">void</span><span class="plain"> </span><span class="functiontext">Dictionaries::write_value</span><span class="plain">(</span><span class="reserved">dictionary</span><span class="plain"> *</span><span class="identifier">D</span><span class="plain">, </span><span class="reserved">text_stream</span><span class="plain"> *</span><span class="identifier">key</span><span class="plain">, </span><span class="reserved">void</span><span class="plain"> *</span><span class="identifier">val</span><span class="plain">) {</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">D</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">"wrote to null dictionary"</span><span class="plain">);</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">D</span><span class="plain">-></span><span class="element">textual</span><span class="plain">) </span><span class="identifier">internal_error</span><span class="plain">(</span><span class="string">"textual dictionary accessed as pointy"</span><span class="plain">);</span>
|
|
<span class="reserved">dict_entry</span><span class="plain"> *</span><span class="identifier">E</span><span class="plain"> = </span><span class="functiontext">Dictionaries::find</span><span class="plain">(</span><span class="identifier">D</span><span class="plain">, </span><span class="identifier">key</span><span class="plain">);</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">E</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">"wrote null dictionary entry"</span><span class="plain">);</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">E</span><span class="plain">-></span><span class="element">vacant</span><span class="plain">) </span><span class="identifier">internal_error</span><span class="plain">(</span><span class="string">"wrote vacant dictionary entry"</span><span class="plain">);</span>
|
|
<span class="identifier">E</span><span class="plain">-></span><span class="element">value</span><span class="plain"> = </span><span class="identifier">val</span><span class="plain">;</span>
|
|
<span class="plain">}</span>
|
|
<span class="reserved">void</span><span class="plain"> </span><span class="functiontext">Dictionaries::write_value_literal</span><span class="plain">(</span><span class="reserved">dictionary</span><span class="plain"> *</span><span class="identifier">D</span><span class="plain">, </span><span class="identifier">wchar_t</span><span class="plain"> *</span><span class="identifier">key</span><span class="plain">, </span><span class="reserved">void</span><span class="plain"> *</span><span class="identifier">val</span><span class="plain">) {</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">D</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">"wrote to null dictionary"</span><span class="plain">);</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">D</span><span class="plain">-></span><span class="element">textual</span><span class="plain">) </span><span class="identifier">internal_error</span><span class="plain">(</span><span class="string">"textual dictionary accessed as pointy"</span><span class="plain">);</span>
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<span class="reserved">dict_entry</span><span class="plain"> *</span><span class="identifier">E</span><span class="plain"> = </span><span class="functiontext">Dictionaries::find_literal</span><span class="plain">(</span><span class="identifier">D</span><span class="plain">, </span><span class="identifier">key</span><span class="plain">);</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">E</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">"wrote null dictionary entry"</span><span class="plain">);</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">E</span><span class="plain">-></span><span class="element">vacant</span><span class="plain">) </span><span class="identifier">internal_error</span><span class="plain">(</span><span class="string">"wrote vacant dictionary entry"</span><span class="plain">);</span>
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<span class="identifier">E</span><span class="plain">-></span><span class="element">value</span><span class="plain"> = </span><span class="identifier">val</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="endnote">The function Dictionaries::read_value is used in 3/cla (<a href="3-cla.html#SP13">§13</a>).</p>
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<p class="endnote">The function Dictionaries::read_value_literal appears nowhere else.</p>
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<p class="endnote">The function Dictionaries::write_value is used in 3/cla (<a href="3-cla.html#SP5">§5</a>).</p>
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<p class="endnote">The function Dictionaries::write_value_literal appears nowhere else.</p>
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<p class="inwebparagraph"><a id="SP9"></a><b>§9. </b>But the commonest use case is that the dictionary stores texts as values,
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so we provide convenient wrappers with the correct C types.
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</p>
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<pre class="display">
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<span class="reserved">text_stream</span><span class="plain"> *</span><span class="functiontext">Dictionaries::create_text</span><span class="plain">(</span><span class="reserved">dictionary</span><span class="plain"> *</span><span class="identifier">D</span><span class="plain">, </span><span class="reserved">text_stream</span><span class="plain"> *</span><span class="identifier">key</span><span class="plain">) {</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">D</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">"wrote to null dictionary"</span><span class="plain">);</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">D</span><span class="plain">-></span><span class="element">textual</span><span class="plain"> == </span><span class="constant">FALSE</span><span class="plain">) </span><span class="identifier">internal_error</span><span class="plain">(</span><span class="string">"pointy dictionary accessed as textual"</span><span class="plain">);</span>
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<span class="reserved">dict_entry</span><span class="plain"> *</span><span class="identifier">E</span><span class="plain"> = </span><span class="functiontext">Dictionaries::create</span><span class="plain">(</span><span class="identifier">D</span><span class="plain">, </span><span class="identifier">key</span><span class="plain">);</span>
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<span class="reserved">return</span><span class="plain"> (</span><span class="reserved">text_stream</span><span class="plain"> *) </span><span class="identifier">E</span><span class="plain">-></span><span class="element">value</span><span class="plain">;</span>
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<span class="plain">}</span>
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<span class="reserved">text_stream</span><span class="plain"> *</span><span class="functiontext">Dictionaries::create_text_literal</span><span class="plain">(</span><span class="reserved">dictionary</span><span class="plain"> *</span><span class="identifier">D</span><span class="plain">, </span><span class="identifier">wchar_t</span><span class="plain"> *</span><span class="identifier">lit</span><span class="plain">) {</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">D</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">"wrote to null dictionary"</span><span class="plain">);</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">D</span><span class="plain">-></span><span class="element">textual</span><span class="plain"> == </span><span class="constant">FALSE</span><span class="plain">) </span><span class="identifier">internal_error</span><span class="plain">(</span><span class="string">"pointy dictionary accessed as textual"</span><span class="plain">);</span>
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<span class="reserved">dict_entry</span><span class="plain"> *</span><span class="identifier">E</span><span class="plain"> = </span><span class="functiontext">Dictionaries::create_literal</span><span class="plain">(</span><span class="identifier">D</span><span class="plain">, </span><span class="identifier">lit</span><span class="plain">);</span>
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<span class="reserved">return</span><span class="plain"> (</span><span class="reserved">text_stream</span><span class="plain"> *) </span><span class="identifier">E</span><span class="plain">-></span><span class="element">value</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="endnote">The function Dictionaries::create_text appears nowhere else.</p>
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<p class="endnote">The function Dictionaries::create_text_literal appears nowhere else.</p>
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<p class="inwebparagraph"><a id="SP10"></a><b>§10. </b>We only need a read operation, because the caller can write to the dictionary
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entry by reading the text pointer and then using <code class="display"><span class="extract">WRITE_TO</span></code>.
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</p>
|
|
|
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<pre class="display">
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<span class="reserved">text_stream</span><span class="plain"> *</span><span class="functiontext">Dictionaries::get_text</span><span class="plain">(</span><span class="reserved">dictionary</span><span class="plain"> *</span><span class="identifier">D</span><span class="plain">, </span><span class="reserved">text_stream</span><span class="plain"> *</span><span class="identifier">key</span><span class="plain">) {</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">D</span><span class="plain"> == </span><span class="identifier">NULL</span><span class="plain">) </span><span class="reserved">return</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">D</span><span class="plain">-></span><span class="element">textual</span><span class="plain"> == </span><span class="constant">FALSE</span><span class="plain">) </span><span class="identifier">internal_error</span><span class="plain">(</span><span class="string">"pointy dictionary accessed as textual"</span><span class="plain">);</span>
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<span class="reserved">dict_entry</span><span class="plain"> *</span><span class="identifier">E</span><span class="plain"> = </span><span class="functiontext">Dictionaries::find</span><span class="plain">(</span><span class="identifier">D</span><span class="plain">, </span><span class="identifier">key</span><span class="plain">);</span>
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|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">E</span><span class="plain"> == </span><span class="identifier">NULL</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="identifier">NULL</span><span class="plain">;</span>
|
|
<span class="reserved">return</span><span class="plain"> (</span><span class="reserved">text_stream</span><span class="plain"> *) </span><span class="identifier">E</span><span class="plain">-></span><span class="element">value</span><span class="plain">;</span>
|
|
<span class="plain">}</span>
|
|
|
|
<span class="reserved">text_stream</span><span class="plain"> *</span><span class="functiontext">Dictionaries::get_text_literal</span><span class="plain">(</span><span class="reserved">dictionary</span><span class="plain"> *</span><span class="identifier">D</span><span class="plain">, </span><span class="identifier">wchar_t</span><span class="plain"> *</span><span class="identifier">lit</span><span class="plain">) {</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">D</span><span class="plain"> == </span><span class="identifier">NULL</span><span class="plain">) </span><span class="reserved">return</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">D</span><span class="plain">-></span><span class="element">textual</span><span class="plain"> == </span><span class="constant">FALSE</span><span class="plain">) </span><span class="identifier">internal_error</span><span class="plain">(</span><span class="string">"pointy dictionary accessed as textual"</span><span class="plain">);</span>
|
|
<span class="reserved">dict_entry</span><span class="plain"> *</span><span class="identifier">E</span><span class="plain"> = </span><span class="functiontext">Dictionaries::find_literal</span><span class="plain">(</span><span class="identifier">D</span><span class="plain">, </span><span class="identifier">lit</span><span class="plain">);</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">E</span><span class="plain"> == </span><span class="identifier">NULL</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="identifier">NULL</span><span class="plain">;</span>
|
|
<span class="reserved">return</span><span class="plain"> (</span><span class="reserved">text_stream</span><span class="plain"> *) </span><span class="identifier">E</span><span class="plain">-></span><span class="element">value</span><span class="plain">;</span>
|
|
<span class="plain">}</span>
|
|
</pre>
|
|
|
|
<p class="inwebparagraph"></p>
|
|
|
|
<p class="endnote">The function Dictionaries::get_text appears nowhere else.</p>
|
|
|
|
<p class="endnote">The function Dictionaries::get_text_literal is used in 4/sm (<a href="4-sm.html#SP26_1">§26.1</a>).</p>
|
|
|
|
<p class="inwebparagraph"><a id="SP11"></a><b>§11. Disposal. </b>If a dictionary was only needed temporarily then we should dispose of it
|
|
and free the memory when done:
|
|
</p>
|
|
|
|
<pre class="display">
|
|
<span class="reserved">void</span><span class="plain"> </span><span class="functiontext">Dictionaries::dispose_of</span><span class="plain">(</span><span class="reserved">dictionary</span><span class="plain"> *</span><span class="identifier">D</span><span class="plain">) {</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">D</span><span class="plain">-></span><span class="element">textual</span><span class="plain">)</span>
|
|
<span class="reserved">for</span><span class="plain"> (</span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">i</span><span class="plain">=0; </span><span class="identifier">i</span><span class="plain"><</span><span class="identifier">D</span><span class="plain">-></span><span class="element">hash_table_size</span><span class="plain">; </span><span class="identifier">i</span><span class="plain">++)</span>
|
|
<span class="reserved">for</span><span class="plain"> (</span><span class="reserved">dict_entry</span><span class="plain"> *</span><span class="identifier">E</span><span class="plain"> = &(</span><span class="identifier">D</span><span class="plain">-></span><span class="element">hash_table</span><span class="plain">[</span><span class="identifier">i</span><span class="plain">]); </span><span class="identifier">E</span><span class="plain">; </span><span class="identifier">E</span><span class="plain"> = </span><span class="identifier">E</span><span class="plain">-></span><span class="element">next_in_entry</span><span class="plain">)</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">E</span><span class="plain">-></span><span class="element">vacant</span><span class="plain"> == </span><span class="constant">FALSE</span><span class="plain">)</span>
|
|
<span class="functiontext">Str::dispose_of</span><span class="plain">(</span><span class="identifier">E</span><span class="plain">-></span><span class="element">value</span><span class="plain">);</span>
|
|
<span class="functiontext">Memory::I7_free</span><span class="plain">(</span><span class="identifier">D</span><span class="plain">-></span><span class="element">hash_table</span><span class="plain">, </span><span class="constant">DICTIONARY_MREASON</span><span class="plain">, </span><span class="identifier">D</span><span class="plain">-></span><span class="element">hash_table_size</span><span class="plain">*((</span><span class="reserved">int</span><span class="plain">) </span><span class="reserved">sizeof</span><span class="plain">(</span><span class="reserved">dict_entry</span><span class="plain">)));</span>
|
|
<span class="identifier">D</span><span class="plain">-></span><span class="element">hash_table</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="endnote">The function Dictionaries::dispose_of appears nowhere else.</p>
|
|
|
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<hr class="tocbar">
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<ul class="toc"><li><a href="2-llas.html">Back to 'Linked Lists and Stacks'</a></li><li><i>(This section ends Chapter 2: Memory, Streams and Collections.)</i></li></ul><hr class="tocbar">
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<!--End of weave-->
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