ifhub/inform7
1
0
Fork 0
mirror of https://github.com/ganelson/inform.git synced 2024-07-17 06:24:24 +03:00
Code Issues Projects Releases Wiki Activity
inform7/docs/words-module/4-bn.html
Graham Nelson c49ce42a2e New-style weave navigation
2020-03-19 00:11:25 +00:00

195 lines
15 KiB
HTML
Raw Blame History

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<title>4/prf</title>
<meta name="viewport" content="width=device-width initial-scale=1">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta http-equiv="Content-Language" content="en-gb">
<link href="../inweb.css" rel="stylesheet" rev="stylesheet" type="text/css">
</head>
<body>
<nav role="navigation">
<h1><a href="../webs.html">Sources</a></h1>
<ul>
<li><a href="../compiler.html"><b>compiler</b></a></li>
<li><a href="../other.html">other tools</a></li>
<li><a href="../extensions.html">extensions and kits</a></li>
<li><a href="../units.html">unit test tools</a></li>
</ul>
<h2>Compiler Webs</h2>
<ul>
<li><a href="../inbuild/index.html">inbuild</a></li>
<li><a href="../inform7/index.html">inform7</a></li>
<li><a href="../inter/index.html">inter</a></li>
</ul>
<h2>Inbuild Modules</h2>
<ul>
<li><a href="../inbuild-module/index.html">inbuild</a></li>
<li><a href="../arch-module/index.html">arch</a></li>
<li><a href="../words-module/index.html">words</a></li>
<li><a href="../syntax-module/index.html">syntax</a></li>
<li><a href="../html-module/index.html">html</a></li>
</ul>
<h2>Inform7 Modules</h2>
<ul>
<li><a href="../core-module/index.html">core</a></li>
<li><a href="../problems-module/index.html">problems</a></li>
<li><a href="../inflections-module/index.html">inflections</a></li>
<li><a href="../linguistics-module/index.html">linguistics</a></li>
<li><a href="../kinds-module/index.html">kinds</a></li>
<li><a href="../if-module/index.html">if</a></li>
<li><a href="../multimedia-module/index.html">multimedia</a></li>
<li><a href="../index-module/index.html">index</a></li>
</ul>
<h2>Inter Modules</h2>
<ul>
<li><a href="../inter-module/index.html">inter</a></li>
<li><a href="../building-module/index.html">building</a></li>
<li><a href="../codegen-module/index.html">codegen</a></li>
</ul>
<h2>Foundation</h2>
<ul>
<li><a href="../../../inweb/docs/foundation-module/index.html">foundation</a></li>
</ul>
</nav>
<main role="main">
<!--Weave of '4/bn' generated by 7-->
<ul class="crumbs"><li><a href="../webs.html">Source</a></li><li><a href="../compiler.html">Compiler</a></li><li><a href="index.html">words</a></li><li><a href="index.html#4">Chapter 4: Parsing</a></li><li><b>Basic Nonterminals</b></li></ul><p class="purpose">A handful of bare minimum Preform syntax.</p>
<ul class="toc"><li><a href="#SP1">&#167;1. Text positions</a></li><li><a href="#SP3">&#167;3. Balancing</a></li><li><a href="#SP5">&#167;5. Literal numbers</a></li><li><a href="#SP6">&#167;6. Literal text</a></li></ul><hr class="tocbar">
<p class="inwebparagraph"><a id="SP1"></a><b>&#167;1. Text positions. </b>A useful nonterminal which matches no text, but detects the position:
</p>
<pre class="display">
<span class="plain">&lt;</span><span class="reserved">if</span><span class="plain">-</span><span class="identifier">start</span><span class="plain">-</span><span class="identifier">of</span><span class="plain">-</span><span class="identifier">paragraph</span><span class="plain">&gt; </span><span class="identifier">internal</span><span class="plain"> 0 {</span>
<span class="reserved">int</span><span class="plain"> </span><span class="identifier">w1</span><span class="plain"> = </span><span class="functiontext">Wordings::first_wn</span><span class="plain">(</span><span class="identifier">W</span><span class="plain">);</span>
<span class="reserved">if</span><span class="plain"> ((</span><span class="identifier">w1</span><span class="plain"> == 0) || (</span><span class="identifier">compare_word</span><span class="plain">(</span><span class="identifier">w1</span><span class="plain">-1, </span><span class="identifier">PARBREAK_V</span><span class="plain">))) </span><span class="reserved">return</span><span class="plain"> </span><span class="identifier">TRUE</span><span class="plain">;</span>
<span class="reserved">return</span><span class="plain"> </span><span class="identifier">FALSE</span><span class="plain">;</span>
<span class="plain">}</span>
</pre>
<p class="inwebparagraph"></p>
<p class="inwebparagraph"><a id="SP2"></a><b>&#167;2. </b>And another convenience:
</p>
<pre class="display">
<span class="plain">&lt;</span><span class="reserved">if</span><span class="plain">-</span><span class="identifier">not</span><span class="plain">-</span><span class="identifier">deliberately</span><span class="plain">-</span><span class="identifier">capitalised</span><span class="plain">&gt; </span><span class="identifier">internal</span><span class="plain"> 0 {</span>
<span class="reserved">int</span><span class="plain"> </span><span class="identifier">w1</span><span class="plain"> = </span><span class="functiontext">Wordings::first_wn</span><span class="plain">(</span><span class="identifier">W</span><span class="plain">);</span>
<span class="reserved">if</span><span class="plain"> (</span><span class="functiontext">Word::unexpectedly_upper_case</span><span class="plain">(</span><span class="identifier">w1</span><span class="plain">) == </span><span class="identifier">FALSE</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="identifier">TRUE</span><span class="plain">;</span>
<span class="reserved">return</span><span class="plain"> </span><span class="identifier">FALSE</span><span class="plain">;</span>
<span class="plain">}</span>
</pre>
<p class="inwebparagraph"></p>
<p class="inwebparagraph"><a id="SP3"></a><b>&#167;3. Balancing. </b>The following matches any text in which braces and brackets are correctly
paired.
</p>
<pre class="display">
<span class="plain">&lt;</span><span class="identifier">balanced</span><span class="plain">-</span><span class="identifier">text</span><span class="plain">&gt; ::=</span>
<span class="plain">......</span>
</pre>
<p class="inwebparagraph"></p>
<p class="inwebparagraph"><a id="SP4"></a><b>&#167;4. </b>Inform contains relatively few syntaxes where commas are actually required,
though they can optionally be used in many lists, as here:
</p>
<blockquote>
<p>parma ham, camembert, grapes</p>
</blockquote>
<p class="inwebparagraph">But for when we only want to spot comma placements, this can be used. Note
that the comma matches only if not in brackets.
</p>
<pre class="display">
<span class="plain">&lt;</span><span class="identifier">list</span><span class="plain">-</span><span class="identifier">comma</span><span class="plain">-</span><span class="identifier">division</span><span class="plain">&gt; ::=</span>
<span class="plain">...... , ......</span>
</pre>
<p class="inwebparagraph"></p>
<p class="inwebparagraph"><a id="SP5"></a><b>&#167;5. Literal numbers. </b>(Inform itself doesn't use this, but has alternatives for cardinals and
ordinals within the VM-representable range.)
</p>
<pre class="display">
<span class="plain">&lt;</span><span class="identifier">any</span><span class="plain">-</span><span class="identifier">integer</span><span class="plain">&gt; </span><span class="identifier">internal</span><span class="plain"> 1 {</span>
<span class="reserved">if</span><span class="plain"> (</span><span class="functiontext">Vocabulary::test_flags</span><span class="plain">(</span><span class="functiontext">Wordings::first_wn</span><span class="plain">(</span><span class="identifier">W</span><span class="plain">), </span><span class="constant">NUMBER_MC</span><span class="plain">)) {</span>
<span class="plain">*</span><span class="identifier">X</span><span class="plain"> = </span><span class="functiontext">Vocabulary::get_literal_number_value</span><span class="plain">(</span><span class="functiontext">Lexer::word</span><span class="plain">(</span><span class="functiontext">Wordings::first_wn</span><span class="plain">(</span><span class="identifier">W</span><span class="plain">)));</span>
<span class="reserved">return</span><span class="plain"> </span><span class="identifier">TRUE</span><span class="plain">;</span>
<span class="plain">}</span>
<span class="reserved">return</span><span class="plain"> </span><span class="identifier">FALSE</span><span class="plain">;</span>
<span class="plain">}</span>
</pre>
<p class="inwebparagraph"></p>
<p class="inwebparagraph"><a id="SP6"></a><b>&#167;6. Literal text. </b>Text is "with substitutions" if it contains square brackets, used in Inform
for interpolations called "text substitutions".
</p>
<pre class="display">
<span class="plain">&lt;</span><span class="identifier">quoted</span><span class="plain">-</span><span class="identifier">text</span><span class="plain">&gt; </span><span class="identifier">internal</span><span class="plain"> 1 {</span>
<span class="reserved">if</span><span class="plain"> ((</span><span class="functiontext">Wordings::nonempty</span><span class="plain">(</span><span class="identifier">W</span><span class="plain">)) &amp;&amp; (</span><span class="functiontext">Vocabulary::test_flags</span><span class="plain">(</span><span class="functiontext">Wordings::first_wn</span><span class="plain">(</span><span class="identifier">W</span><span class="plain">), </span><span class="constant">TEXT_MC</span><span class="plain">+</span><span class="constant">TEXTWITHSUBS_MC</span><span class="plain">))) {</span>
<span class="plain">*</span><span class="identifier">X</span><span class="plain"> = </span><span class="functiontext">Wordings::first_wn</span><span class="plain">(</span><span class="identifier">W</span><span class="plain">); </span><span class="reserved">return</span><span class="plain"> </span><span class="identifier">TRUE</span><span class="plain">;</span>
<span class="plain">}</span>
<span class="reserved">return</span><span class="plain"> </span><span class="identifier">FALSE</span><span class="plain">;</span>
<span class="plain">}</span>
<span class="plain">&lt;</span><span class="identifier">quoted</span><span class="plain">-</span><span class="identifier">text</span><span class="plain">-</span><span class="identifier">with</span><span class="plain">-</span><span class="identifier">subs</span><span class="plain">&gt; </span><span class="identifier">internal</span><span class="plain"> 1 {</span>
<span class="reserved">if</span><span class="plain"> ((</span><span class="functiontext">Wordings::nonempty</span><span class="plain">(</span><span class="identifier">W</span><span class="plain">)) &amp;&amp; (</span><span class="functiontext">Vocabulary::test_flags</span><span class="plain">(</span><span class="functiontext">Wordings::first_wn</span><span class="plain">(</span><span class="identifier">W</span><span class="plain">), </span><span class="constant">TEXTWITHSUBS_MC</span><span class="plain">))) {</span>
<span class="plain">*</span><span class="identifier">X</span><span class="plain"> = </span><span class="functiontext">Wordings::first_wn</span><span class="plain">(</span><span class="identifier">W</span><span class="plain">); </span><span class="reserved">return</span><span class="plain"> </span><span class="identifier">TRUE</span><span class="plain">;</span>
<span class="plain">}</span>
<span class="reserved">return</span><span class="plain"> </span><span class="identifier">FALSE</span><span class="plain">;</span>
<span class="plain">}</span>
<span class="plain">&lt;</span><span class="identifier">quoted</span><span class="plain">-</span><span class="identifier">text</span><span class="plain">-</span><span class="identifier">without</span><span class="plain">-</span><span class="identifier">subs</span><span class="plain">&gt; </span><span class="identifier">internal</span><span class="plain"> 1 {</span>
<span class="reserved">if</span><span class="plain"> ((</span><span class="functiontext">Wordings::nonempty</span><span class="plain">(</span><span class="identifier">W</span><span class="plain">)) &amp;&amp; (</span><span class="functiontext">Vocabulary::test_flags</span><span class="plain">(</span><span class="functiontext">Wordings::first_wn</span><span class="plain">(</span><span class="identifier">W</span><span class="plain">), </span><span class="constant">TEXT_MC</span><span class="plain">))) {</span>
<span class="plain">*</span><span class="identifier">X</span><span class="plain"> = </span><span class="functiontext">Wordings::first_wn</span><span class="plain">(</span><span class="identifier">W</span><span class="plain">); </span><span class="reserved">return</span><span class="plain"> </span><span class="identifier">TRUE</span><span class="plain">;</span>
<span class="plain">}</span>
<span class="reserved">return</span><span class="plain"> </span><span class="identifier">FALSE</span><span class="plain">;</span>
<span class="plain">}</span>
</pre>
<p class="inwebparagraph"></p>
<p class="inwebparagraph"><a id="SP7"></a><b>&#167;7. </b>For finicky technical reasons the easiest way to detect an empty piece
of text <code class="display"><span class="extract">""</span></code> is to provide a nonterminal matching it:
</p>
<pre class="display">
<span class="plain">&lt;</span><span class="identifier">empty</span><span class="plain">-</span><span class="identifier">text</span><span class="plain">&gt; </span><span class="identifier">internal</span><span class="plain"> 1 {</span>
<span class="reserved">if</span><span class="plain"> ((</span><span class="functiontext">Wordings::nonempty</span><span class="plain">(</span><span class="identifier">W</span><span class="plain">)) &amp;&amp; (</span><span class="functiontext">Word::compare_by_strcmp</span><span class="plain">(</span><span class="functiontext">Wordings::first_wn</span><span class="plain">(</span><span class="identifier">W</span><span class="plain">), </span><span class="identifier">L</span><span class="string">"\</span><span class="plain">"</span><span class="string">\</span><span class="plain">"</span><span class="string">"</span><span class="plain">))) {</span>
<span class="plain">*</span><span class="identifier">X</span><span class="plain"> = </span><span class="functiontext">Wordings::first_wn</span><span class="plain">(</span><span class="identifier">W</span><span class="plain">); </span><span class="reserved">return</span><span class="plain"> </span><span class="identifier">TRUE</span><span class="plain">;</span>
<span class="plain">}</span>
<span class="reserved">return</span><span class="plain"> </span><span class="identifier">FALSE</span><span class="plain">;</span>
<span class="plain">}</span>
</pre>
<p class="inwebparagraph"></p>
<hr class="tocbar">
<ul class="toc"><li><a href="4-prf.html">Back to 'Preform'</a></li><li><i>(This section ends Chapter 4: Parsing.)</i></li></ul><hr class="tocbar">
<!--End of weave-->
</main>
</body>
</html>
Reference in a new issue View git blame Copy permalink