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<li><a href="../../../intest/index.html">intest</a></li>
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<main role="main">
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<!--Weave of 'Closures' 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="../inform7n.html">Inform7</a></li><li><a href="index.html">imperative</a></li><li><a href="index.html#3">Chapter 3: Functions</a></li><li><b>Closures</b></li></ul></div>
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<p class="purpose">To provide the names of phrases as first-class values.</p>
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<p class="commentary firstcommentary"><a id="SP1" class="paragraph-anchor"></a><b>§1. </b>Phrases which have been given names can be used as first-class values in
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Inform, meaning that they can be stored in variables, have a kind which can
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be expressed in Inform source text, and so on.
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</p>
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<p class="commentary">At runtime, it might be expected that such a constant would be stored just as
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the address of the function. In fact it is stored as (the address of) a small
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fixed-size array called a "closure", which does include the function address,
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but also some metadata about it.
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</p>
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<p class="commentary">In the theory of compilers, the term "closure" is usually used more ambitiously
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than this, in that closures "capture" references to local variables, thus enabling
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"closed" functions to be made out of fragments occurring inside code. For example,
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in the Swift programming language:
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</p>
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<pre class="displayed-code all-displayed-code code-font">
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<span class="plain-syntax"> var threshold = 10</span>
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<span class="plain-syntax"> let fn = { x in return x > threshold }</span>
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<span class="plain-syntax"> return fn</span>
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</pre>
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<p class="commentary">a nameless function has been made with <span class="extract"><span class="extract-syntax">{ x in return x > threshold }</span></span> which
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includes a reference to a local variable not part of its own definition, i.e.,
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<span class="extract"><span class="extract-syntax">threshold</span></span>. A reference to this must be "captured" and salted away in the
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closure data, since otherwise by the time the <span class="extract"><span class="extract-syntax">fn</span></span> value is used, <span class="extract"><span class="extract-syntax">threshold</span></span>
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will not exist.
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</p>
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<p class="commentary">This issue does not arise for Inform because, at present, there is no lambda
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operator, or syntax like Swift's <span class="extract"><span class="extract-syntax">{ x in ... }</span></span>, for making one phrase inside
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the body of another one.<sup id="fnref:1"><a href="#fn:1" rel="footnote">1</a></sup> So we never need capture anything, and phrases are
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never half-open and so in that sense do not need closing, but we will continue
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to use the flattering term "closure" anyway.
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</p>
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<ul class="footnotetexts"><li class="footnote" id="fn:1"><p class="inwebfootnote"><sup id="fnref:1"><a href="#fn:1" rel="footnote">1</a></sup> Unless you count text substitutions, where exactly this issue of capturing
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values does arise.
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<a href="#fnref:1" title="return to text"> ↩</a></p></li></ul>
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<p class="commentary firstcommentary"><a id="SP2" class="paragraph-anchor"></a><b>§2. </b>This returns the iname for a closure array for <span class="extract"><span class="extract-syntax">cphr</span></span>. Since each phrase can
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have at most one closure, and they occupy little memory, we do not need to
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create or destroy them dynamically as small blocks: we can simply store them
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in memory at known locations, and the iname here refers to that location.
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</p>
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<pre class="displayed-code all-displayed-code code-font">
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<span class="identifier-syntax">inter_name</span><span class="plain-syntax"> *</span><span class="function-syntax">Closures::iname</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">Closures::iname</span></span>:<br/><a href="3-cls.html#SP3_1">§3.1</a><br/>Compile Rvalues - <a href="2-cr.html#SP1_3">§1.3</a></span></button><span class="plain-syntax">(</span><span class="identifier-syntax">constant_phrase</span><span class="plain-syntax"> *</span><span class="identifier-syntax">cphr</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">cphr</span><span class="plain-syntax">-></span><span class="identifier-syntax">cphr_iname</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) {</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">id_body</span><span class="plain-syntax"> *</span><span class="identifier-syntax">idb</span><span class="plain-syntax"> = </span><span class="identifier-syntax">ToPhraseFamily::body_of_constant</span><span class="plain-syntax">(</span><span class="identifier-syntax">cphr</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">idb</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">"cannot reconstruct phrase from cphr"</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">package_request</span><span class="plain-syntax"> *</span><span class="identifier-syntax">P</span><span class="plain-syntax"> = </span><span class="identifier-syntax">Hierarchy::package_within</span><span class="plain-syntax">(</span><span class="identifier-syntax">CLOSURES_HAP</span><span class="plain-syntax">,</span>
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<span class="plain-syntax"> </span><a href="3-cid.html#SP8" class="function-link"><span class="function-syntax">CompileImperativeDefn::requests_package</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">idb</span><span class="plain-syntax">));</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">cphr</span><span class="plain-syntax">-></span><span class="identifier-syntax">cphr_iname</span><span class="plain-syntax"> = </span><span class="identifier-syntax">Hierarchy::make_iname_in</span><span class="plain-syntax">(</span><span class="identifier-syntax">CLOSURE_DATA_HL</span><span class="plain-syntax">, </span><span class="identifier-syntax">P</span><span class="plain-syntax">);</span>
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<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">cphr</span><span class="plain-syntax">-></span><span class="identifier-syntax">cphr_iname</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>And this is where those arrays are made:
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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">Closures::compile_closures</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="identifier-syntax">constant_phrase</span><span class="plain-syntax"> *</span><span class="identifier-syntax">cphr</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">cphr</span><span class="plain-syntax">, </span><span class="identifier-syntax">constant_phrase</span><span class="plain-syntax">) {</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">id_body</span><span class="plain-syntax"> *</span><span class="identifier-syntax">idb</span><span class="plain-syntax"> = </span><span class="identifier-syntax">ToPhraseFamily::body_of_constant</span><span class="plain-syntax">(</span><span class="identifier-syntax">cphr</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">idb</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">"cannot reconstruct phrase from cphr"</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">ToPhraseFamily::kind</span><span class="plain-syntax">(</span><span class="identifier-syntax">cphr</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="named-paragraph-container code-font"><a href="3-cls.html#SP3_1" class="named-paragraph-link"><span class="named-paragraph">Compile the closure array for this constant phrase</span><span class="named-paragraph-number">3.1</span></a></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="SP3_1" class="paragraph-anchor"></a><b>§3.1. </b>The closure array consists of three words: the strong kind ID, the address
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of the function, and the text of the name. (The latter enables us to print
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phrase values efficiently.) Note that we make a compilation request for the
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phrase in order to make sure somebody has actually compiled it: this is in
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case the phrase occurs as a constant but is never explicitly invoked, as here —
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</p>
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<pre class="displayed-code all-displayed-code code-font">
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<span class="identifier-syntax">To</span><span class="plain-syntax"> </span><span class="identifier-syntax">decide</span><span class="plain-syntax"> </span><span class="identifier-syntax">which</span><span class="plain-syntax"> </span><span class="identifier-syntax">number</span><span class="plain-syntax"> </span><span class="identifier-syntax">is</span><span class="plain-syntax"> (</span><span class="identifier-syntax">N</span><span class="plain-syntax"> - </span><span class="identifier-syntax">a</span><span class="plain-syntax"> </span><span class="identifier-syntax">number</span><span class="plain-syntax">) </span><span class="identifier-syntax">doubled</span><span class="plain-syntax"> (</span><span class="identifier-syntax">this</span><span class="plain-syntax"> </span><span class="identifier-syntax">is</span><span class="plain-syntax"> </span><span class="identifier-syntax">doubling</span><span class="plain-syntax">):</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">decide</span><span class="plain-syntax"> </span><span class="identifier-syntax">on</span><span class="plain-syntax"> </span><span class="identifier-syntax">N</span><span class="plain-syntax"> + </span><span class="identifier-syntax">N</span><span class="plain-syntax">.</span>
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<span class="identifier-syntax">To</span><span class="plain-syntax"> </span><span class="identifier-syntax">begin</span><span class="plain-syntax">:</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">let</span><span class="plain-syntax"> </span><span class="identifier-syntax">L</span><span class="plain-syntax"> </span><span class="identifier-syntax">be</span><span class="plain-syntax"> { </span><span class="constant-syntax">2</span><span class="plain-syntax">, </span><span class="constant-syntax">3</span><span class="plain-syntax">, </span><span class="constant-syntax">5</span><span class="plain-syntax">, </span><span class="constant-syntax">7</span><span class="plain-syntax">, </span><span class="constant-syntax">11</span><span class="plain-syntax"> };</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">say</span><span class="plain-syntax"> </span><span class="string-syntax">"Doubling produces [doubling applied to L]."</span>
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</pre>
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<p class="commentary">In this source text, there is never an explicit invocation such as "4 doubled",
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but the fact that the phrase has been given the name "doubling" is enough to
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ensure that the closure array for it is compiled, and that forces a request
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for the underlying function's compilation.
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</p>
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<p class="commentary"><span class="named-paragraph-container code-font"><span class="named-paragraph-defn">Compile the closure array for this constant phrase</span><span class="named-paragraph-number">3.1</span></span><span class="comment-syntax"> =</span>
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</p>
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<pre class="displayed-code all-displayed-code code-font">
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<span class="plain-syntax"> </span><span class="identifier-syntax">inter_name</span><span class="plain-syntax"> *</span><span class="identifier-syntax">iname</span><span class="plain-syntax"> = </span><a href="3-cls.html#SP2" class="function-link"><span class="function-syntax">Closures::iname</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">cphr</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">packaging_state</span><span class="plain-syntax"> </span><span class="identifier-syntax">save</span><span class="plain-syntax"> = </span><span class="identifier-syntax">EmitArrays::begin_word</span><span class="plain-syntax">(</span><span class="identifier-syntax">iname</span><span class="plain-syntax">, </span><span class="identifier-syntax">K_value</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">RTKindIDs::strong_ID_array_entry</span><span class="plain-syntax">(</span><span class="identifier-syntax">cphr</span><span class="plain-syntax">-></span><span class="identifier-syntax">cphr_kind</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">inter_name</span><span class="plain-syntax"> *</span><span class="identifier-syntax">RS</span><span class="plain-syntax"> = </span><a href="3-pr.html#SP1" class="function-link"><span class="function-syntax">PhraseRequests::simple_request</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">idb</span><span class="plain-syntax">, </span><span class="identifier-syntax">ToPhraseFamily::kind</span><span class="plain-syntax">(</span><span class="identifier-syntax">cphr</span><span class="plain-syntax">));</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">EmitArrays::iname_entry</span><span class="plain-syntax">(</span><span class="identifier-syntax">RS</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">TEMPORARY_TEXT</span><span class="plain-syntax">(</span><span class="identifier-syntax">name</span><span class="plain-syntax">)</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE_TO</span><span class="plain-syntax">(</span><span class="identifier-syntax">name</span><span class="plain-syntax">, </span><span class="string-syntax">"%W"</span><span class="plain-syntax">, </span><span class="identifier-syntax">Nouns::nominative_singular</span><span class="plain-syntax">(</span><span class="identifier-syntax">cphr</span><span class="plain-syntax">-></span><span class="identifier-syntax">name</span><span class="plain-syntax">));</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">EmitArrays::text_entry</span><span class="plain-syntax">(</span><span class="identifier-syntax">name</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">DISCARD_TEXT</span><span class="plain-syntax">(</span><span class="identifier-syntax">name</span><span class="plain-syntax">)</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">EmitArrays::end</span><span class="plain-syntax">(</span><span class="identifier-syntax">save</span><span class="plain-syntax">);</span>
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</pre>
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<ul class="endnotetexts"><li>This code is used in <a href="3-cls.html#SP3">§3</a>.</li></ul>
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<p class="commentary firstcommentary"><a id="SP4" class="paragraph-anchor"></a><b>§4. </b>Now we come to something trickier. We want default values for kinds of phrases,
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because otherwise we can't have variables holding phrases unless they are
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always initialised explicitly, and so on. Clearly the default value for a
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phrase to nothing is one that does nothing, and for a phrase to some kind K
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is one that returns the default value of kind K. For example, the default
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value of
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</p>
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<pre class="displayed-code all-displayed-code code-font">
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<span class="plain-syntax"> phrase (text, time) -> number</span>
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</pre>
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<p class="commentary">is the function which takes any pair of a text and a time, does nothing with
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them, and always returns the default number, i.e., 0. But this means we need
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to actually compile such functions. Since there are in principle an infinite
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number of distinct phrase kinds, we will only compile them for the phrase kinds
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which actually arise during compilation.
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</p>
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<p class="commentary">The following function is called exactly once for each such kind <span class="extract"><span class="extract-syntax">K</span></span>.
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</p>
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<pre class="displayed-code all-displayed-code code-font">
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<span class="reserved-syntax">typedef</span><span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="reserved-syntax">default_closure_request</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">inter_name</span><span class="plain-syntax"> *</span><span class="identifier-syntax">closure_identifier</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">kind</span><span class="plain-syntax"> *</span><span class="identifier-syntax">K</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">default_closure_request</span><span class="plain-syntax">;</span>
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<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Closures::compile_default_closure</span><span class="plain-syntax">(</span><span class="identifier-syntax">inter_name</span><span class="plain-syntax"> *</span><span class="identifier-syntax">closure_identifier</span><span class="plain-syntax">, </span><span class="identifier-syntax">kind</span><span class="plain-syntax"> *</span><span class="identifier-syntax">K</span><span class="plain-syntax">) {</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">desc</span><span class="plain-syntax"> = </span><span class="identifier-syntax">Str::new</span><span class="plain-syntax">();</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE_TO</span><span class="plain-syntax">(</span><span class="identifier-syntax">desc</span><span class="plain-syntax">, </span><span class="string-syntax">"default closure for %u"</span><span class="plain-syntax">, </span><span class="identifier-syntax">K</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">default_closure_request</span><span class="plain-syntax"> *</span><span class="identifier-syntax">dcr</span><span class="plain-syntax"> = </span><span class="identifier-syntax">CREATE</span><span class="plain-syntax">(</span><span class="reserved-syntax">default_closure_request</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">dcr</span><span class="plain-syntax">-></span><span class="element-syntax">closure_identifier</span><span class="plain-syntax"> = </span><span class="identifier-syntax">closure_identifier</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">dcr</span><span class="plain-syntax">-></span><span class="element-syntax">K</span><span class="plain-syntax"> = </span><span class="identifier-syntax">K</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">Sequence::queue</span><span class="plain-syntax">(&</span><a href="3-cls.html#SP5" class="function-link"><span class="function-syntax">Closures::compilation_agent</span></a><span class="plain-syntax">, </span><span class="identifier-syntax">STORE_POINTER_default_closure_request</span><span class="plain-syntax">(</span><span class="identifier-syntax">dcr</span><span class="plain-syntax">), </span><span class="identifier-syntax">desc</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 default_closure_request is private to this section.</li></ul>
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<p class="commentary firstcommentary"><a id="SP5" class="paragraph-anchor"></a><b>§5. </b>And the actual compilation is done here, when we can be certain that no other
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function is being compiled at the same time.
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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">Closures::compilation_agent</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">Closures::compilation_agent</span></span>:<br/><a href="3-cls.html#SP4">§4</a></span></button><span class="plain-syntax">(</span><span class="identifier-syntax">compilation_subtask</span><span class="plain-syntax"> *</span><span class="identifier-syntax">t</span><span class="plain-syntax">) {</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">default_closure_request</span><span class="plain-syntax"> *</span><span class="identifier-syntax">dcr</span><span class="plain-syntax"> = </span><span class="identifier-syntax">RETRIEVE_POINTER_default_closure_request</span><span class="plain-syntax">(</span><span class="identifier-syntax">t</span><span class="plain-syntax">-></span><span class="identifier-syntax">data</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">package_request</span><span class="plain-syntax"> *</span><span class="identifier-syntax">P</span><span class="plain-syntax"> = </span><span class="identifier-syntax">RTKindConstructors::kind_package</span><span class="plain-syntax">(</span><span class="identifier-syntax">dcr</span><span class="plain-syntax">-></span><span class="element-syntax">K</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">inter_name</span><span class="plain-syntax"> *</span><span class="identifier-syntax">rname</span><span class="plain-syntax"> = </span><span class="identifier-syntax">Hierarchy::make_iname_in</span><span class="plain-syntax">(</span><span class="identifier-syntax">DEFAULT_CLOSURE_FN_HL</span><span class="plain-syntax">, </span><span class="identifier-syntax">P</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="named-paragraph-container code-font"><a href="3-cls.html#SP5_1" class="named-paragraph-link"><span class="named-paragraph">Compile the default function</span><span class="named-paragraph-number">5.1</span></a></span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="named-paragraph-container code-font"><a href="3-cls.html#SP5_2" class="named-paragraph-link"><span class="named-paragraph">Compile its closure</span><span class="named-paragraph-number">5.2</span></a></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_1" class="paragraph-anchor"></a><b>§5.1. </b><span class="named-paragraph-container code-font"><span class="named-paragraph-defn">Compile the default function</span><span class="named-paragraph-number">5.1</span></span><span class="comment-syntax"> =</span>
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</p>
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<pre class="displayed-code all-displayed-code code-font">
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<span class="plain-syntax"> </span><span class="identifier-syntax">packaging_state</span><span class="plain-syntax"> </span><span class="identifier-syntax">save</span><span class="plain-syntax"> = </span><a href="3-fnc.html#SP2" class="function-link"><span class="function-syntax">Functions::begin</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">rname</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><a href="3-lv.html#SP4" class="function-link"><span class="function-syntax">LocalVariables::new_other_parameter</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">I</span><span class="string-syntax">"a"</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><a href="3-lv.html#SP4" class="function-link"><span class="function-syntax">LocalVariables::new_other_parameter</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">I</span><span class="string-syntax">"b"</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><a href="3-lv.html#SP4" class="function-link"><span class="function-syntax">LocalVariables::new_other_parameter</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">I</span><span class="string-syntax">"c"</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><a href="3-lv.html#SP4" class="function-link"><span class="function-syntax">LocalVariables::new_other_parameter</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">I</span><span class="string-syntax">"d"</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><a href="3-lv.html#SP4" class="function-link"><span class="function-syntax">LocalVariables::new_other_parameter</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">I</span><span class="string-syntax">"e"</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><a href="3-lv.html#SP4" class="function-link"><span class="function-syntax">LocalVariables::new_other_parameter</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">I</span><span class="string-syntax">"f"</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><a href="3-lv.html#SP4" class="function-link"><span class="function-syntax">LocalVariables::new_other_parameter</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">I</span><span class="string-syntax">"g"</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><a href="3-lv.html#SP4" class="function-link"><span class="function-syntax">LocalVariables::new_other_parameter</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">I</span><span class="string-syntax">"h"</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">kind</span><span class="plain-syntax"> *</span><span class="identifier-syntax">result</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">Kinds::binary_construction_material</span><span class="plain-syntax">(</span><span class="identifier-syntax">dcr</span><span class="plain-syntax">-></span><span class="element-syntax">K</span><span class="plain-syntax">, </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">, &</span><span class="identifier-syntax">result</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">Kinds::get_construct</span><span class="plain-syntax">(</span><span class="identifier-syntax">result</span><span class="plain-syntax">) != </span><span class="identifier-syntax">CON_NIL</span><span class="plain-syntax">) {</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">EmitCode::inv</span><span class="plain-syntax">(</span><span class="identifier-syntax">RETURN_BIP</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">EmitCode::down</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">Kinds::Behaviour::uses_block_values</span><span class="plain-syntax">(</span><span class="identifier-syntax">result</span><span class="plain-syntax">)) {</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">inter_name</span><span class="plain-syntax"> *</span><span class="identifier-syntax">iname</span><span class="plain-syntax"> = </span><span class="identifier-syntax">Hierarchy::find</span><span class="plain-syntax">(</span><span class="identifier-syntax">BLKVALUECREATE_HL</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">EmitCode::call</span><span class="plain-syntax">(</span><span class="identifier-syntax">iname</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">EmitCode::down</span><span class="plain-syntax">();</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">RTKindIDs::emit_strong_ID_as_val</span><span class="plain-syntax">(</span><span class="identifier-syntax">result</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">EmitCode::up</span><span class="plain-syntax">();</span>
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<span class="plain-syntax"> } </span><span class="reserved-syntax">else</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">DefaultValues::val</span><span class="plain-syntax">(</span><span class="identifier-syntax">result</span><span class="plain-syntax">, </span><span class="identifier-syntax">EMPTY_WORDING</span><span class="plain-syntax">, </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) != </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">)</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">EmitCode::val_number</span><span class="plain-syntax">(0);</span>
|
|
<span class="plain-syntax"> }</span>
|
|
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">EmitCode::up</span><span class="plain-syntax">();</span>
|
|
<span class="plain-syntax"> }</span>
|
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<span class="plain-syntax"> </span><a href="3-fnc.html#SP6" class="function-link"><span class="function-syntax">Functions::end</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">save</span><span class="plain-syntax">);</span>
|
|
</pre>
|
|
<ul class="endnotetexts"><li>This code is used in <a href="3-cls.html#SP5">§5</a>.</li></ul>
|
|
<p class="commentary firstcommentary"><a id="SP5_2" class="paragraph-anchor"></a><b>§5.2. </b><span class="named-paragraph-container code-font"><span class="named-paragraph-defn">Compile its closure</span><span class="named-paragraph-number">5.2</span></span><span class="comment-syntax"> =</span>
|
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</p>
|
|
|
|
<pre class="displayed-code all-displayed-code code-font">
|
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<span class="plain-syntax"> </span><span class="identifier-syntax">packaging_state</span><span class="plain-syntax"> </span><span class="identifier-syntax">save</span><span class="plain-syntax"> = </span><span class="identifier-syntax">EmitArrays::begin_word</span><span class="plain-syntax">(</span><span class="identifier-syntax">dcr</span><span class="plain-syntax">-></span><span class="element-syntax">closure_identifier</span><span class="plain-syntax">, </span><span class="identifier-syntax">K_value</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">RTKindIDs::strong_ID_array_entry</span><span class="plain-syntax">(</span><span class="identifier-syntax">dcr</span><span class="plain-syntax">-></span><span class="element-syntax">K</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">EmitArrays::iname_entry</span><span class="plain-syntax">(</span><span class="identifier-syntax">rname</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">TEMPORARY_TEXT</span><span class="plain-syntax">(</span><span class="identifier-syntax">DVT</span><span class="plain-syntax">)</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE_TO</span><span class="plain-syntax">(</span><span class="identifier-syntax">DVT</span><span class="plain-syntax">, </span><span class="string-syntax">"default value of "</span><span class="plain-syntax">); </span><span class="identifier-syntax">Kinds::Textual::write</span><span class="plain-syntax">(</span><span class="identifier-syntax">DVT</span><span class="plain-syntax">, </span><span class="identifier-syntax">dcr</span><span class="plain-syntax">-></span><span class="element-syntax">K</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">EmitArrays::text_entry</span><span class="plain-syntax">(</span><span class="identifier-syntax">DVT</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">DISCARD_TEXT</span><span class="plain-syntax">(</span><span class="identifier-syntax">DVT</span><span class="plain-syntax">)</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">EmitArrays::end</span><span class="plain-syntax">(</span><span class="identifier-syntax">save</span><span class="plain-syntax">);</span>
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</pre>
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<ul class="endnotetexts"><li>This code is used in <a href="3-cls.html#SP5">§5</a>.</li></ul>
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