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<title>Feature Manager</title>
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<h1><a href="../index.html">
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</a></h1>
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<ul><li><a href="../index.html">home</a></li>
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</ul><h2>Compiler</h2><ul>
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<li><a href="../structure.html">structure</a></li>
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<li><a href="../intern.html">inter</a></li>
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<li><a href="https://github.com/ganelson/inform"><img src="../docs-assets/github.png" height=18> github</a></li>
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</ul><h2>Related Projects</h2><ul>
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<li><a href="../../../inweb/index.html">inweb</a></li>
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<li><a href="../../../intest/index.html">intest</a></li>
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</ul>
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<main role="main">
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<!--Weave of 'Feature Manager' generated by Inweb-->
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<div class="breadcrumbs">
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<ul class="crumbs"><li><a href="../index.html">Home</a></li><li><a href="../services.html">Services</a></li><li><a href="index.html">arch</a></li><li><a href="index.html#3">Chapter 3: Features</a></li><li><b>Feature Manager</b></li></ul></div>
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<p class="purpose">Creating, activating or deactivating compiler features.</p>
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<p class="commentary firstcommentary"><a id="SP1" class="paragraph-anchor"></a><b>§1. </b>"Features" are optional pieces of compiler functionality, which are given
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textual names. They can be "activated" or "deactivated", that is, on or off.
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For example, some of the interactive-fiction support in the Inform compiler
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is provided by features which are deactivated for Basic Inform projects.
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Incompletely implemented, or experimental, functions under development can
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also be gated behind features which are deactivated by default, and activated
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just for test projects.
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</p>
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<p class="commentary">It turns out to be convenient to have a hard-wired maximum number of these.
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But since features are not things an author can create in source text, we always
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know exactly how many there are.
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</p>
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<pre class="definitions code-font"><span class="definition-keyword">define</span> <span class="constant-syntax">MAX_COMPILER_FEATURES</span><span class="plain-syntax"> </span><span class="constant-syntax">32</span>
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</pre>
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<pre class="displayed-code all-displayed-code code-font">
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<span class="reserved-syntax">typedef</span><span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="reserved-syntax">compiler_feature</span><span class="plain-syntax"> {</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">textual_name</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="reserved-syntax">compiler_feature</span><span class="plain-syntax"> *</span><span class="identifier-syntax">parent_feature</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">void</span><span class="plain-syntax"> (*</span><span class="identifier-syntax">activation_function</span><span class="plain-syntax">)(</span><span class="reserved-syntax">void</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">active</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">permanently_active</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">activation_function_run</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">CLASS_DEFINITION</span>
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<span class="plain-syntax">} </span><span class="reserved-syntax">compiler_feature</span><span class="plain-syntax">;</span>
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<span class="reserved-syntax">compiler_feature</span><span class="plain-syntax"> *</span><span class="function-syntax">Features::new</span><button class="popup" onclick="togglePopup('usagePopup1')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup1">Usage of <span class="code-font"><span class="function-syntax">Features::new</span></span>:<br/><a href="3-fm.html#SP9">§9</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">void</span><span class="plain-syntax"> (*</span><span class="identifier-syntax">starter</span><span class="plain-syntax">)(</span><span class="reserved-syntax">void</span><span class="plain-syntax">), </span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">tname</span><span class="plain-syntax">, </span><span class="reserved-syntax">compiler_feature</span><span class="plain-syntax"> *</span><span class="identifier-syntax">set</span><span class="plain-syntax">) {</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">compiler_feature</span><span class="plain-syntax"> *</span><span class="identifier-syntax">F</span><span class="plain-syntax"> = </span><span class="identifier-syntax">CREATE</span><span class="plain-syntax">(</span><span class="reserved-syntax">compiler_feature</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">F</span><span class="plain-syntax">-></span><span class="element-syntax">textual_name</span><span class="plain-syntax"> = </span><span class="identifier-syntax">Str::duplicate</span><span class="plain-syntax">(</span><span class="identifier-syntax">tname</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">F</span><span class="plain-syntax">-></span><span class="element-syntax">activation_function</span><span class="plain-syntax"> = </span><span class="identifier-syntax">starter</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">F</span><span class="plain-syntax">-></span><span class="element-syntax">active</span><span class="plain-syntax"> = </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">F</span><span class="plain-syntax">-></span><span class="element-syntax">parent_feature</span><span class="plain-syntax"> = </span><span class="identifier-syntax">set</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">F</span><span class="plain-syntax">-></span><span class="element-syntax">activation_function_run</span><span class="plain-syntax"> = </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">F</span><span class="plain-syntax">-></span><span class="identifier-syntax">allocation_id</span><span class="plain-syntax"> >= </span><span class="constant-syntax">MAX_COMPILER_FEATURES</span><span class="plain-syntax">)</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">internal_error</span><span class="plain-syntax">(</span><span class="string-syntax">"too many features"</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">F</span><span class="plain-syntax">;</span>
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<span class="plain-syntax">}</span>
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</pre>
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<ul class="endnotetexts"><li>The structure compiler_feature is private to this section.</li></ul>
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<p class="commentary firstcommentary"><a id="SP2" class="paragraph-anchor"></a><b>§2. </b>With so few features in existence, there's no need to do this more efficiently:
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</p>
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<pre class="displayed-code all-displayed-code code-font">
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<span class="reserved-syntax">compiler_feature</span><span class="plain-syntax"> *</span><span class="function-syntax">Features::from_name</span><span class="plain-syntax">(</span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">S</span><span class="plain-syntax">) {</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">compiler_feature</span><span class="plain-syntax"> *</span><span class="identifier-syntax">F</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">LOOP_OVER</span><span class="plain-syntax">(</span><span class="identifier-syntax">F</span><span class="plain-syntax">, </span><span class="reserved-syntax">compiler_feature</span><span class="plain-syntax">)</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">Str::eq_insensitive</span><span class="plain-syntax">(</span><span class="identifier-syntax">F</span><span class="plain-syntax">-></span><span class="element-syntax">textual_name</span><span class="plain-syntax">, </span><span class="identifier-syntax">S</span><span class="plain-syntax">))</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">F</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">;</span>
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<span class="plain-syntax">}</span>
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</pre>
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<p class="commentary firstcommentary"><a id="SP3" class="paragraph-anchor"></a><b>§3. </b>The idea is that an inactive feature does nothing; it's as if that section of
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code were not in the compiler at all. These provide convenient shorthand ways
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to test that:
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</p>
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<pre class="definitions code-font"><span class="definition-keyword">define</span> <span class="identifier-syntax">FEATURE_ACTIVE</span><span class="plain-syntax">(</span><span class="identifier-syntax">name</span><span class="plain-syntax">) </span><a href="3-fm.html#SP3" class="function-link"><span class="function-syntax">Features::active</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">name</span><span class="plain-syntax">##</span><span class="identifier-syntax">_feature</span><span class="plain-syntax">)</span>
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<span class="definition-keyword">define</span> <span class="identifier-syntax">FEATURE_INACTIVE</span><span class="plain-syntax">(</span><span class="identifier-syntax">name</span><span class="plain-syntax">) (</span><a href="3-fm.html#SP3" class="function-link"><span class="function-syntax">Features::active</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">name</span><span class="plain-syntax">##</span><span class="identifier-syntax">_feature</span><span class="plain-syntax">) == </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">)</span>
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</pre>
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<pre class="displayed-code all-displayed-code code-font">
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<span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="function-syntax">Features::active</span><span class="plain-syntax">(</span><span class="reserved-syntax">compiler_feature</span><span class="plain-syntax"> *</span><span class="identifier-syntax">F</span><span class="plain-syntax">) {</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">F</span><span class="plain-syntax">-></span><span class="element-syntax">active</span><span class="plain-syntax">;</span>
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<span class="plain-syntax">}</span>
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<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Features::list</span><span class="plain-syntax">(</span><span class="identifier-syntax">OUTPUT_STREAM</span><span class="plain-syntax">, </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">state</span><span class="plain-syntax">, </span><span class="reserved-syntax">compiler_feature</span><span class="plain-syntax"> *</span><span class="identifier-syntax">except</span><span class="plain-syntax">) {</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">compiler_feature</span><span class="plain-syntax"> *</span><span class="identifier-syntax">F</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">c</span><span class="plain-syntax"> = </span><span class="constant-syntax">0</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">LOOP_OVER</span><span class="plain-syntax">(</span><span class="identifier-syntax">F</span><span class="plain-syntax">, </span><span class="reserved-syntax">compiler_feature</span><span class="plain-syntax">) </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">F</span><span class="plain-syntax">-></span><span class="element-syntax">active</span><span class="plain-syntax"> == </span><span class="identifier-syntax">state</span><span class="plain-syntax">)</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((</span><span class="identifier-syntax">except</span><span class="plain-syntax"> == </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">) || (</span><a href="3-fm.html#SP5" class="function-link"><span class="function-syntax">Features::part_of</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">F</span><span class="plain-syntax">, </span><span class="identifier-syntax">except</span><span class="plain-syntax">) == </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">)) {</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">c</span><span class="plain-syntax"> > </span><span class="constant-syntax">0</span><span class="plain-syntax">) </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">", "</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">"%S"</span><span class="plain-syntax">, </span><span class="identifier-syntax">F</span><span class="plain-syntax">-></span><span class="element-syntax">textual_name</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">c</span><span class="plain-syntax">++;</span>
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<span class="plain-syntax"> }</span>
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<span class="plain-syntax">}</span>
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</pre>
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<p class="commentary firstcommentary"><a id="SP4" class="paragraph-anchor"></a><b>§4. </b>In the code above, features are set up as inactive by default — even "core",
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which the compiler absolutely cannot live without. So <a href="../supervisor-module/5-ps2.html" class="internal">Project Services (in supervisor)</a>
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calls the following before switching on optional things that it wants.
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</p>
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<pre class="displayed-code all-displayed-code code-font">
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<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Features::activate_bare_minimum</span><span class="plain-syntax">(</span><span class="reserved-syntax">void</span><span class="plain-syntax">) {</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">compiler_feature</span><span class="plain-syntax"> *</span><span class="identifier-syntax">F</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">LOOP_OVER</span><span class="plain-syntax">(</span><span class="identifier-syntax">F</span><span class="plain-syntax">, </span><span class="reserved-syntax">compiler_feature</span><span class="plain-syntax">)</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((</span><span class="identifier-syntax">F</span><span class="plain-syntax">-></span><span class="element-syntax">permanently_active</span><span class="plain-syntax">) && (</span><span class="identifier-syntax">F</span><span class="plain-syntax">-></span><span class="element-syntax">active</span><span class="plain-syntax"> == </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">))</span>
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<span class="plain-syntax"> </span><a href="3-fm.html#SP6" class="function-link"><span class="function-syntax">Features::activate</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">F</span><span class="plain-syntax">);</span>
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<span class="plain-syntax">}</span>
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<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Features::make_permanently_active</span><button class="popup" onclick="togglePopup('usagePopup2')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup2">Usage of <span class="code-font"><span class="function-syntax">Features::make_permanently_active</span></span>:<br/><a href="3-fm.html#SP9">§9</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">compiler_feature</span><span class="plain-syntax"> *</span><span class="identifier-syntax">F</span><span class="plain-syntax">) {</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">F</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) </span><span class="identifier-syntax">internal_error</span><span class="plain-syntax">(</span><span class="string-syntax">"no feature"</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">F</span><span class="plain-syntax">-></span><span class="element-syntax">permanently_active</span><span class="plain-syntax"> = </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">;</span>
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<span class="plain-syntax">}</span>
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</pre>
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<p class="commentary firstcommentary"><a id="SP5" class="paragraph-anchor"></a><b>§5. </b>Most features are subordinate to a parent feature: for example, a dozen more
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specific IF-related features are subordinate to the "interactive fiction" one.
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</p>
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<pre class="displayed-code all-displayed-code code-font">
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<span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="function-syntax">Features::part_of</span><button class="popup" onclick="togglePopup('usagePopup3')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup3">Usage of <span class="code-font"><span class="function-syntax">Features::part_of</span></span>:<br/><a href="3-fm.html#SP3">§3</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">compiler_feature</span><span class="plain-syntax"> *</span><span class="identifier-syntax">F</span><span class="plain-syntax">, </span><span class="reserved-syntax">compiler_feature</span><span class="plain-syntax"> *</span><span class="identifier-syntax">G</span><span class="plain-syntax">) {</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">while</span><span class="plain-syntax"> ((</span><span class="identifier-syntax">F</span><span class="plain-syntax"> != </span><span class="identifier-syntax">G</span><span class="plain-syntax">) && (</span><span class="identifier-syntax">F</span><span class="plain-syntax"> != </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">)) </span><span class="identifier-syntax">F</span><span class="plain-syntax"> = </span><span class="identifier-syntax">F</span><span class="plain-syntax">-></span><span class="element-syntax">parent_feature</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">F</span><span class="plain-syntax"> == </span><span class="identifier-syntax">G</span><span class="plain-syntax">) </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
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<span class="plain-syntax">}</span>
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</pre>
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<p class="commentary firstcommentary"><a id="SP6" class="paragraph-anchor"></a><b>§6. </b>Activating or deactivating a parent like that automatically activates
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or deactivates its children.
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</p>
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<pre class="displayed-code all-displayed-code code-font">
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<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Features::activate</span><button class="popup" onclick="togglePopup('usagePopup4')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup4">Usage of <span class="code-font"><span class="function-syntax">Features::activate</span></span>:<br/><a href="3-fm.html#SP4">§4</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">compiler_feature</span><span class="plain-syntax"> *</span><span class="identifier-syntax">F</span><span class="plain-syntax">) {</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((</span><span class="identifier-syntax">F</span><span class="plain-syntax">) && (</span><span class="identifier-syntax">F</span><span class="plain-syntax">-></span><span class="element-syntax">active</span><span class="plain-syntax"> == </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">)) {</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">F</span><span class="plain-syntax">-></span><span class="identifier-syntax">active</span><span class="plain-syntax"> = </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><a href="3-fm.html#SP8" class="function-link"><span class="function-syntax">Features::run_activation_function</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">F</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">compiler_feature</span><span class="plain-syntax"> *</span><span class="identifier-syntax">G</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">LOOP_OVER</span><span class="plain-syntax">(</span><span class="identifier-syntax">G</span><span class="plain-syntax">, </span><span class="reserved-syntax">compiler_feature</span><span class="plain-syntax">)</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">G</span><span class="plain-syntax">-></span><span class="element-syntax">parent_feature</span><span class="plain-syntax"> == </span><span class="identifier-syntax">F</span><span class="plain-syntax">)</span>
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<span class="plain-syntax"> </span><a href="3-fm.html#SP6" class="function-link"><span class="function-syntax">Features::activate</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">G</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> }</span>
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<span class="plain-syntax">}</span>
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</pre>
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<p class="commentary firstcommentary"><a id="SP7" class="paragraph-anchor"></a><b>§7. </b>Whereas anything can be activated, some things cannot be deactivated, so the
|
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following returns a success flag:
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</p>
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<pre class="displayed-code all-displayed-code code-font">
|
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<span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="function-syntax">Features::deactivate</span><span class="plain-syntax">(</span><span class="reserved-syntax">compiler_feature</span><span class="plain-syntax"> *</span><span class="identifier-syntax">F</span><span class="plain-syntax">) {</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((</span><span class="identifier-syntax">F</span><span class="plain-syntax">) && (</span><span class="identifier-syntax">F</span><span class="plain-syntax">-></span><span class="element-syntax">active</span><span class="plain-syntax">)) {</span>
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|
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">F</span><span class="plain-syntax">-></span><span class="element-syntax">permanently_active</span><span class="plain-syntax">) </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">F</span><span class="plain-syntax">-></span><span class="identifier-syntax">active</span><span class="plain-syntax"> = </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
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|
<span class="plain-syntax"> </span><span class="reserved-syntax">compiler_feature</span><span class="plain-syntax"> *</span><span class="identifier-syntax">G</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">LOOP_OVER</span><span class="plain-syntax">(</span><span class="identifier-syntax">G</span><span class="plain-syntax">, </span><span class="reserved-syntax">compiler_feature</span><span class="plain-syntax">)</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">G</span><span class="plain-syntax">-></span><span class="element-syntax">parent_feature</span><span class="plain-syntax"> == </span><span class="identifier-syntax">F</span><span class="plain-syntax">)</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><a href="3-fm.html#SP7" class="function-link"><span class="function-syntax">Features::deactivate</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">G</span><span class="plain-syntax">) == </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">)</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax"> }</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax">}</span>
|
|
</pre>
|
|
<p class="commentary firstcommentary"><a id="SP8" class="paragraph-anchor"></a><b>§8. </b>Every active feature gets to run its start function, if it provides one.
|
|
But this is postponed until <a href="3-fm.html#SP8" class="internal">Features::run_activation_functions</a> is called;
|
|
at that point, every activated feature runs its function. If any feature is
|
|
activated after this point, its function runs immediately. (The point of the
|
|
postponement is that very early in Inform's run, the memory manager may not
|
|
yet be working, and so on.)
|
|
</p>
|
|
|
|
<p class="commentary">It's kind of incredible that C's grammar for round brackets is unambiguous.
|
|
</p>
|
|
|
|
<pre class="displayed-code all-displayed-code code-font">
|
|
<span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">allow_activation_functions_to_be_run</span><span class="plain-syntax"> = </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
|
|
|
|
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Features::allow_activation_functions</span><span class="plain-syntax">(</span><span class="reserved-syntax">void</span><span class="plain-syntax">) {</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">allow_activation_functions_to_be_run</span><span class="plain-syntax"> = </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax">}</span>
|
|
|
|
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Features::run_activation_functions</span><span class="plain-syntax">(</span><span class="reserved-syntax">void</span><span class="plain-syntax">) {</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">compiler_feature</span><span class="plain-syntax"> *</span><span class="identifier-syntax">F</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">LOOP_OVER</span><span class="plain-syntax">(</span><span class="identifier-syntax">F</span><span class="plain-syntax">, </span><span class="reserved-syntax">compiler_feature</span><span class="plain-syntax">)</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">F</span><span class="plain-syntax">-></span><span class="element-syntax">active</span><span class="plain-syntax">)</span>
|
|
<span class="plain-syntax"> </span><a href="3-fm.html#SP8" class="function-link"><span class="function-syntax">Features::run_activation_function</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">F</span><span class="plain-syntax">);</span>
|
|
<span class="plain-syntax">}</span>
|
|
|
|
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Features::run_activation_function</span><button class="popup" onclick="togglePopup('usagePopup5')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup5">Usage of <span class="code-font"><span class="function-syntax">Features::run_activation_function</span></span>:<br/><a href="3-fm.html#SP6">§6</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">compiler_feature</span><span class="plain-syntax"> *</span><span class="identifier-syntax">F</span><span class="plain-syntax">) {</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((</span><span class="identifier-syntax">allow_activation_functions_to_be_run</span><span class="plain-syntax">) && (</span><span class="identifier-syntax">F</span><span class="plain-syntax">) &&</span>
|
|
<span class="plain-syntax"> (</span><span class="identifier-syntax">F</span><span class="plain-syntax">-></span><span class="element-syntax">activation_function_run</span><span class="plain-syntax"> == </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">)) {</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">F</span><span class="plain-syntax">-></span><span class="identifier-syntax">activation_function_run</span><span class="plain-syntax"> = </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">F</span><span class="plain-syntax">-></span><span class="element-syntax">activation_function</span><span class="plain-syntax">) (*(</span><span class="identifier-syntax">F</span><span class="plain-syntax">-></span><span class="element-syntax">activation_function</span><span class="plain-syntax">))();</span>
|
|
<span class="plain-syntax"> }</span>
|
|
<span class="plain-syntax">}</span>
|
|
</pre>
|
|
<p class="commentary firstcommentary"><a id="SP9" class="paragraph-anchor"></a><b>§9. </b>Basic features which are present in all three Inform compiler tools:
|
|
</p>
|
|
|
|
<pre class="displayed-code all-displayed-code code-font">
|
|
<span class="reserved-syntax">compiler_feature</span><span class="plain-syntax"> *</span><span class="identifier-syntax">core_feature</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">, *</span><span class="identifier-syntax">experimental_feature</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">,</span>
|
|
<span class="plain-syntax"> *</span><span class="identifier-syntax">dialogue_feature</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">, *</span><span class="identifier-syntax">concepts_feature</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">;</span>
|
|
|
|
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Features::activate_core</span><span class="plain-syntax">(</span><span class="reserved-syntax">void</span><span class="plain-syntax">) {</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">core_feature</span><span class="plain-syntax"> = </span><a href="3-fm.html#SP1" class="function-link"><span class="function-syntax">Features::new</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">NULL</span><span class="plain-syntax">, </span><span class="identifier-syntax">I</span><span class="string-syntax">"core"</span><span class="plain-syntax">, </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">);</span>
|
|
<span class="plain-syntax"> </span><a href="3-fm.html#SP4" class="function-link"><span class="function-syntax">Features::make_permanently_active</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">core_feature</span><span class="plain-syntax">);</span>
|
|
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">experimental_feature</span><span class="plain-syntax"> = </span><a href="3-fm.html#SP1" class="function-link"><span class="function-syntax">Features::new</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">NULL</span><span class="plain-syntax">, </span><span class="identifier-syntax">I</span><span class="string-syntax">"experimental features"</span><span class="plain-syntax">, </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">);</span>
|
|
<span class="plain-syntax"> #</span><span class="identifier-syntax">ifdef</span><span class="plain-syntax"> </span><span class="identifier-syntax">IF_MODULE</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">dialogue_feature</span><span class="plain-syntax"> = </span><a href="3-fm.html#SP1" class="function-link"><span class="function-syntax">Features::new</span></a><span class="plain-syntax">(&</span><span class="identifier-syntax">Dialogue::start</span><span class="plain-syntax">, </span><span class="identifier-syntax">I</span><span class="string-syntax">"dialogue"</span><span class="plain-syntax">, </span><span class="identifier-syntax">experimental_feature</span><span class="plain-syntax">);</span>
|
|
<span class="plain-syntax"> #</span><span class="identifier-syntax">endif</span>
|
|
<span class="plain-syntax"> #</span><span class="identifier-syntax">ifndef</span><span class="plain-syntax"> </span><span class="identifier-syntax">IF_MODULE</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">dialogue_feature</span><span class="plain-syntax"> = </span><a href="3-fm.html#SP1" class="function-link"><span class="function-syntax">Features::new</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">NULL</span><span class="plain-syntax">, </span><span class="identifier-syntax">I</span><span class="string-syntax">"dialogue"</span><span class="plain-syntax">, </span><span class="identifier-syntax">experimental_feature</span><span class="plain-syntax">);</span>
|
|
<span class="plain-syntax"> #</span><span class="identifier-syntax">endif</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">concepts_feature</span><span class="plain-syntax"> = </span><a href="3-fm.html#SP1" class="function-link"><span class="function-syntax">Features::new</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">NULL</span><span class="plain-syntax">, </span><span class="identifier-syntax">I</span><span class="string-syntax">"concepts"</span><span class="plain-syntax">, </span><span class="identifier-syntax">dialogue_feature</span><span class="plain-syntax">);</span>
|
|
<span class="plain-syntax">}</span>
|
|
</pre>
|
|
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