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433 lines
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HTML
433 lines
19 KiB
HTML
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<ul class="sections">
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<li id="title">
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<div class="annotation">
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<h1>scope.litcoffee</h1>
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</div>
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</li>
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<li id="section-1">
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<div class="annotation">
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<div class="pilwrap">
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<a class="pilcrow" href="#section-1">¶</a>
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</div>
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<p>The <strong>Scope</strong> class regulates lexical scoping within CoffeeScript. As you
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generate code, you create a tree of scopes in the same shape as the nested
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function bodies. Each scope knows about the variables declared within it,
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and has a reference to its parent enclosing scope. In this way, we know which
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variables are new and need to be declared with <code>var</code>, and which are shared
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with external scopes.
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</p>
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<p>Import the helpers we plan to use.
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</p>
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</div>
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<div class="content"><div class="highlight"><pre><span class="p">{</span><span class="nx">extend</span><span class="p">,</span> <span class="nx">last</span><span class="p">}</span> <span class="o">=</span> <span class="nx">require</span> <span class="s">'./helpers'</span>
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<span class="nv">exports.Scope = </span><span class="k">class</span> <span class="nx">Scope</span></pre></div></div>
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</li>
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<li id="section-2">
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<div class="annotation">
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<div class="pilwrap">
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<a class="pilcrow" href="#section-2">¶</a>
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</div>
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<p>The <code>root</code> is the top-level <strong>Scope</strong> object for a given file.
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</p>
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</div>
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<div class="content"><div class="highlight"><pre> <span class="vi">@root: </span><span class="kc">null</span></pre></div></div>
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</li>
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<li id="section-3">
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<div class="annotation">
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<div class="pilwrap">
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<a class="pilcrow" href="#section-3">¶</a>
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</div>
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<p>Initialize a scope with its parent, for lookups up the chain,
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as well as a reference to the <strong>Block</strong> node it belongs to, which is
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where it should declare its variables, and a reference to the function that
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it belongs to.
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</p>
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</div>
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<div class="content"><div class="highlight"><pre> <span class="nv">constructor: </span><span class="nf">(@parent, @expressions, @method) -></span>
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<span class="vi">@variables = </span><span class="p">[{</span><span class="nv">name: </span><span class="s">'arguments'</span><span class="p">,</span> <span class="nv">type: </span><span class="s">'arguments'</span><span class="p">}]</span>
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<span class="vi">@positions = </span><span class="p">{}</span>
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<span class="nv">Scope.root = </span><span class="k">this</span> <span class="k">unless</span> <span class="nx">@parent</span></pre></div></div>
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</li>
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<li id="section-4">
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<div class="annotation">
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<div class="pilwrap">
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<a class="pilcrow" href="#section-4">¶</a>
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</div>
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<p>Adds a new variable or overrides an existing one.
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</p>
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</div>
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<div class="content"><div class="highlight"><pre> <span class="nv">add: </span><span class="nf">(name, type, immediate) -></span>
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<span class="k">return</span> <span class="nx">@parent</span><span class="p">.</span><span class="nx">add</span> <span class="nx">name</span><span class="p">,</span> <span class="nx">type</span><span class="p">,</span> <span class="nx">immediate</span> <span class="k">if</span> <span class="nx">@shared</span> <span class="o">and</span> <span class="o">not</span> <span class="nx">immediate</span>
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<span class="k">if</span> <span class="nb">Object</span><span class="o">::</span><span class="nx">hasOwnProperty</span><span class="p">.</span><span class="nx">call</span> <span class="nx">@positions</span><span class="p">,</span> <span class="nx">name</span>
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<span class="nx">@variables</span><span class="p">[</span><span class="nx">@positions</span><span class="p">[</span><span class="nx">name</span><span class="p">]].</span><span class="nv">type = </span><span class="nx">type</span>
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<span class="k">else</span>
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<span class="nx">@positions</span><span class="p">[</span><span class="nx">name</span><span class="p">]</span> <span class="o">=</span> <span class="nx">@variables</span><span class="p">.</span><span class="nx">push</span><span class="p">({</span><span class="nx">name</span><span class="p">,</span> <span class="nx">type</span><span class="p">})</span> <span class="o">-</span> <span class="mi">1</span></pre></div></div>
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</li>
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<li id="section-5">
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<div class="annotation">
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<div class="pilwrap">
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<a class="pilcrow" href="#section-5">¶</a>
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</div>
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<p>When <code>super</code> is called, we need to find the name of the current method we're
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in, so that we know how to invoke the same method of the parent class. This
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can get complicated if super is being called from an inner function.
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<code>namedMethod</code> will walk up the scope tree until it either finds the first
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function object that has a name filled in, or bottoms out.
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</p>
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</div>
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<div class="content"><div class="highlight"><pre> <span class="nv">namedMethod: </span><span class="nf">-></span>
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<span class="k">return</span> <span class="nx">@method</span> <span class="k">if</span> <span class="nx">@method</span><span class="o">?</span><span class="p">.</span><span class="nx">name</span> <span class="o">or</span> <span class="o">!</span><span class="nx">@parent</span>
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<span class="nx">@parent</span><span class="p">.</span><span class="nx">namedMethod</span><span class="p">()</span></pre></div></div>
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</li>
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<li id="section-6">
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<div class="annotation">
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<div class="pilwrap">
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<a class="pilcrow" href="#section-6">¶</a>
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</div>
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<p>Look up a variable name in lexical scope, and declare it if it does not
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already exist.
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</p>
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</div>
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<div class="content"><div class="highlight"><pre> <span class="nv">find: </span><span class="nf">(name) -></span>
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<span class="k">return</span> <span class="kc">yes</span> <span class="k">if</span> <span class="nx">@check</span> <span class="nx">name</span>
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<span class="nx">@add</span> <span class="nx">name</span><span class="p">,</span> <span class="s">'var'</span>
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<span class="kc">no</span></pre></div></div>
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</li>
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<li id="section-7">
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<div class="annotation">
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<div class="pilwrap">
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<a class="pilcrow" href="#section-7">¶</a>
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</div>
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<p>Reserve a variable name as originating from a function parameter for this
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scope. No <code>var</code> required for internal references.
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</p>
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</div>
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<div class="content"><div class="highlight"><pre> <span class="nv">parameter: </span><span class="nf">(name) -></span>
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<span class="k">return</span> <span class="k">if</span> <span class="nx">@shared</span> <span class="o">and</span> <span class="nx">@parent</span><span class="p">.</span><span class="nx">check</span> <span class="nx">name</span><span class="p">,</span> <span class="kc">yes</span>
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<span class="nx">@add</span> <span class="nx">name</span><span class="p">,</span> <span class="s">'param'</span></pre></div></div>
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</li>
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<li id="section-8">
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<div class="annotation">
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<div class="pilwrap">
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<a class="pilcrow" href="#section-8">¶</a>
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</div>
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<p>Just check to see if a variable has already been declared, without reserving,
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walks up to the root scope.
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</p>
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</div>
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<div class="content"><div class="highlight"><pre> <span class="nv">check: </span><span class="nf">(name) -></span>
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<span class="o">!!</span><span class="p">(</span><span class="nx">@type</span><span class="p">(</span><span class="nx">name</span><span class="p">)</span> <span class="o">or</span> <span class="nx">@parent</span><span class="o">?</span><span class="p">.</span><span class="nx">check</span><span class="p">(</span><span class="nx">name</span><span class="p">))</span></pre></div></div>
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</li>
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<li id="section-9">
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<div class="annotation">
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<div class="pilwrap">
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<a class="pilcrow" href="#section-9">¶</a>
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</div>
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<p>Generate a temporary variable name at the given index.
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</p>
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</div>
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<div class="content"><div class="highlight"><pre> <span class="nv">temporary: </span><span class="nf">(name, index) -></span>
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<span class="k">if</span> <span class="nx">name</span><span class="p">.</span><span class="nx">length</span> <span class="o">></span> <span class="mi">1</span>
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<span class="s">'_'</span> <span class="o">+</span> <span class="nx">name</span> <span class="o">+</span> <span class="k">if</span> <span class="nx">index</span> <span class="o">></span> <span class="mi">1</span> <span class="k">then</span> <span class="nx">index</span> <span class="o">-</span> <span class="mi">1</span> <span class="k">else</span> <span class="s">''</span>
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<span class="k">else</span>
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<span class="s">'_'</span> <span class="o">+</span> <span class="p">(</span><span class="nx">index</span> <span class="o">+</span> <span class="nb">parseInt</span> <span class="nx">name</span><span class="p">,</span> <span class="mi">36</span><span class="p">).</span><span class="nx">toString</span><span class="p">(</span><span class="mi">36</span><span class="p">).</span><span class="nx">replace</span> <span class="sr">/\d/g</span><span class="p">,</span> <span class="s">'a'</span></pre></div></div>
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</li>
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<li id="section-10">
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<div class="annotation">
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<div class="pilwrap">
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<a class="pilcrow" href="#section-10">¶</a>
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</div>
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<p>Gets the type of a variable.
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</p>
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</div>
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<div class="content"><div class="highlight"><pre> <span class="nv">type: </span><span class="nf">(name) -></span>
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<span class="k">return</span> <span class="nx">v</span><span class="p">.</span><span class="nx">type</span> <span class="k">for</span> <span class="nx">v</span> <span class="k">in</span> <span class="nx">@variables</span> <span class="k">when</span> <span class="nx">v</span><span class="p">.</span><span class="nx">name</span> <span class="o">is</span> <span class="nx">name</span>
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<span class="kc">null</span></pre></div></div>
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</li>
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<li id="section-11">
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<div class="annotation">
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<div class="pilwrap">
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<a class="pilcrow" href="#section-11">¶</a>
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</div>
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<p>If we need to store an intermediate result, find an available name for a
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compiler-generated variable. <code>_var</code>, <code>_var2</code>, and so on...
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</p>
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</div>
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<div class="content"><div class="highlight"><pre> <span class="nv">freeVariable: </span><span class="nf">(name, reserve=true) -></span>
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<span class="nv">index = </span><span class="mi">0</span>
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<span class="nx">index</span><span class="o">++</span> <span class="k">while</span> <span class="nx">@check</span><span class="p">((</span><span class="nv">temp = </span><span class="nx">@temporary</span> <span class="nx">name</span><span class="p">,</span> <span class="nx">index</span><span class="p">))</span>
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<span class="nx">@add</span> <span class="nx">temp</span><span class="p">,</span> <span class="s">'var'</span><span class="p">,</span> <span class="kc">yes</span> <span class="k">if</span> <span class="nx">reserve</span>
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<span class="nx">temp</span></pre></div></div>
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</li>
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<li id="section-12">
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<div class="annotation">
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<div class="pilwrap">
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<a class="pilcrow" href="#section-12">¶</a>
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</div>
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<p>Ensure that an assignment is made at the top of this scope
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(or at the top-level scope, if requested).
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</p>
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</div>
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<div class="content"><div class="highlight"><pre> <span class="nv">assign: </span><span class="nf">(name, value) -></span>
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<span class="nx">@add</span> <span class="nx">name</span><span class="p">,</span> <span class="p">{</span><span class="nx">value</span><span class="p">,</span> <span class="nv">assigned: </span><span class="kc">yes</span><span class="p">},</span> <span class="kc">yes</span>
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<span class="vi">@hasAssignments = </span><span class="kc">yes</span></pre></div></div>
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</li>
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<li id="section-13">
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<div class="annotation">
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<div class="pilwrap">
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<a class="pilcrow" href="#section-13">¶</a>
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</div>
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<p>Does this scope have any declared variables?
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</p>
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</div>
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<div class="content"><div class="highlight"><pre> <span class="nv">hasDeclarations: </span><span class="nf">-></span>
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<span class="o">!!</span><span class="nx">@declaredVariables</span><span class="p">().</span><span class="nx">length</span></pre></div></div>
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</li>
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<li id="section-14">
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<div class="annotation">
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<div class="pilwrap">
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<a class="pilcrow" href="#section-14">¶</a>
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</div>
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<p>Return the list of variables first declared in this scope.
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</p>
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</div>
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<div class="content"><div class="highlight"><pre> <span class="nv">declaredVariables: </span><span class="nf">-></span>
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<span class="nv">realVars = </span><span class="p">[]</span>
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<span class="nv">tempVars = </span><span class="p">[]</span>
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<span class="k">for</span> <span class="nx">v</span> <span class="k">in</span> <span class="nx">@variables</span> <span class="k">when</span> <span class="nx">v</span><span class="p">.</span><span class="nx">type</span> <span class="o">is</span> <span class="s">'var'</span>
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<span class="p">(</span><span class="k">if</span> <span class="nx">v</span><span class="p">.</span><span class="nx">name</span><span class="p">.</span><span class="nx">charAt</span><span class="p">(</span><span class="mi">0</span><span class="p">)</span> <span class="o">is</span> <span class="s">'_'</span> <span class="k">then</span> <span class="nx">tempVars</span> <span class="k">else</span> <span class="nx">realVars</span><span class="p">).</span><span class="nx">push</span> <span class="nx">v</span><span class="p">.</span><span class="nx">name</span>
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<span class="nx">realVars</span><span class="p">.</span><span class="nx">sort</span><span class="p">().</span><span class="nx">concat</span> <span class="nx">tempVars</span><span class="p">.</span><span class="nx">sort</span><span class="p">()</span></pre></div></div>
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</li>
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<li id="section-15">
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<div class="annotation">
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<div class="pilwrap">
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<a class="pilcrow" href="#section-15">¶</a>
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</div>
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<p>Return the list of assignments that are supposed to be made at the top
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of this scope.
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</p>
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</div>
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<div class="content"><div class="highlight"><pre> <span class="nv">assignedVariables: </span><span class="nf">-></span>
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<span class="s">"</span><span class="si">#{</span><span class="nx">v</span><span class="p">.</span><span class="nx">name</span><span class="si">}</span><span class="s"> = </span><span class="si">#{</span><span class="nx">v</span><span class="p">.</span><span class="nx">type</span><span class="p">.</span><span class="nx">value</span><span class="si">}</span><span class="s">"</span> <span class="k">for</span> <span class="nx">v</span> <span class="k">in</span> <span class="nx">@variables</span> <span class="k">when</span> <span class="nx">v</span><span class="p">.</span><span class="nx">type</span><span class="p">.</span><span class="nx">assigned</span>
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</pre></div></div>
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</li>
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</ul>
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</div>
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</body>
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</html>
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