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48 lines
17 KiB
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<!DOCTYPE html> <html> <head> <title>scope.coffee</title> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <link rel="stylesheet" media="all" href="docco.css" /> </head> <body> <div id="container"> <div id="background"></div> <div id="jump_to"> Jump To … <div id="jump_wrapper"> <div id="jump_page"> <a class="source" href="cake.html"> cake.coffee </a> <a class="source" href="coffee-script.html"> coffee-script.coffee </a> <a class="source" href="command.html"> command.coffee </a> <a class="source" href="grammar.html"> grammar.coffee </a> <a class="source" href="helpers.html"> helpers.coffee </a> <a class="source" href="index.html"> index.coffee </a> <a class="source" href="lexer.html"> lexer.coffee </a> <a class="source" href="nodes.html"> nodes.coffee </a> <a class="source" href="optparse.html"> optparse.coffee </a> <a class="source" href="repl.html"> repl.coffee </a> <a class="source" href="rewriter.html"> rewriter.coffee </a> <a class="source" href="scope.html"> scope.coffee </a> </div> </div> </div> <table cellpadding="0" cellspacing="0"> <thead> <tr> <th class="docs"> <h1> scope.coffee </h1> </th> <th class="code"> </th> </tr> </thead> <tbody> <tr id="section-1"> <td class="docs"> <div class="octowrap"> <a class="octothorpe" href="#section-1">#</a> </div> <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 the outside.</p> </td> <td class="code"> <div class="highlight"><pre></pre></div> </td> </tr> <tr id="section-2"> <td class="docs"> <div class="octowrap"> <a class="octothorpe" href="#section-2">#</a> </div> <p>Set up exported variables for both <strong>Node.js</strong> and the browser.</p> </td> <td class="code"> <div class="highlight"><pre><span class="k">this</span><span class="p">.</span><span class="nv">exports: </span><span class="k">this</span> <span class="nx">unless</span> <span class="nx">process</span><span class="o">?</span>
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<span class="nv">exports.Scope: </span><span class="nx">class</span> <span class="nx">Scope</span></pre></div> </td> </tr> <tr id="section-3"> <td class="docs"> <div class="octowrap"> <a class="octothorpe" href="#section-3">#</a> </div> <p>The top-level <strong>Scope</strong> object.</p> </td> <td class="code"> <div class="highlight"><pre> <span class="vi">@root: </span><span class="kc">null</span></pre></div> </td> </tr> <tr id="section-4"> <td class="docs"> <div class="octowrap"> <a class="octothorpe" href="#section-4">#</a> </div> <p>Initialize a scope with its parent, for lookups up the chain,
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as well as a reference to the <strong>Expressions</strong> node is 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 wraps.</p> </td> <td class="code"> <div class="highlight"><pre> <span class="nv">constructor: </span><span class="p">(</span><span class="nx">parent</span><span class="p">,</span> <span class="nx">expressions</span><span class="p">,</span> <span class="nx">method</span><span class="p">)</span> <span class="o">-></span>
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<span class="p">[</span><span class="nx">@parent</span><span class="p">,</span> <span class="nx">@expressions</span><span class="p">,</span> <span class="nx">@method</span><span class="p">]</span><span class="o">:</span> <span class="p">[</span><span class="nx">parent</span><span class="p">,</span> <span class="nx">expressions</span><span class="p">,</span> <span class="nx">method</span><span class="p">]</span>
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<span class="vi">@variables: </span><span class="p">{}</span>
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<span class="k">if</span> <span class="nx">@parent</span>
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<span class="vi">@temp_var: </span><span class="nx">@parent</span><span class="p">.</span><span class="nx">temp_var</span>
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<span class="k">else</span>
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<span class="nv">Scope.root: </span><span class="k">this</span>
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<span class="vi">@temp_var: </span><span class="s1">'_a'</span></pre></div> </td> </tr> <tr id="section-5"> <td class="docs"> <div class="octowrap"> <a class="octothorpe" href="#section-5">#</a> </div> <p>Look up a variable name in lexical scope, and declare it if it does not
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already exist.</p> </td> <td class="code"> <div class="highlight"><pre> <span class="nv">find: </span><span class="p">(</span><span class="nx">name</span><span class="p">)</span> <span class="o">-></span>
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<span class="k">return</span> <span class="kc">true</span> <span class="k">if</span> <span class="nx">@check</span> <span class="nx">name</span>
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<span class="nx">@variables</span><span class="p">[</span><span class="nx">name</span><span class="p">]</span><span class="o">:</span> <span class="s1">'var'</span>
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<span class="kc">false</span></pre></div> </td> </tr> <tr id="section-6"> <td class="docs"> <div class="octowrap"> <a class="octothorpe" href="#section-6">#</a> </div> <p>Test variables and return true the first time fn(v, k) returns true</p> </td> <td class="code"> <div class="highlight"><pre> <span class="nv">any: </span><span class="p">(</span><span class="nx">fn</span><span class="p">)</span> <span class="o">-></span>
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<span class="k">for</span> <span class="nx">v</span><span class="p">,</span> <span class="nx">k</span> <span class="k">of</span> <span class="nx">@variables</span> <span class="k">when</span> <span class="nx">fn</span><span class="p">(</span><span class="nx">v</span><span class="p">,</span> <span class="nx">k</span><span class="p">)</span>
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<span class="k">return</span> <span class="kc">true</span>
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<span class="k">return</span> <span class="kc">false</span></pre></div> </td> </tr> <tr id="section-7"> <td class="docs"> <div class="octowrap"> <a class="octothorpe" href="#section-7">#</a> </div> <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.</p> </td> <td class="code"> <div class="highlight"><pre> <span class="nv">parameter: </span><span class="p">(</span><span class="nx">name</span><span class="p">)</span> <span class="o">-></span>
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<span class="nx">@variables</span><span class="p">[</span><span class="nx">name</span><span class="p">]</span><span class="o">:</span> <span class="s1">'param'</span></pre></div> </td> </tr> <tr id="section-8"> <td class="docs"> <div class="octowrap"> <a class="octothorpe" href="#section-8">#</a> </div> <p>Just check to see if a variable has already been declared, without reserving.</p> </td> <td class="code"> <div class="highlight"><pre> <span class="nv">check: </span><span class="p">(</span><span class="nx">name</span><span class="p">)</span> <span class="o">-></span>
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<span class="k">return</span> <span class="kc">true</span> <span class="k">if</span> <span class="nx">@variables</span><span class="p">[</span><span class="nx">name</span><span class="p">]</span>
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<span class="o">!!</span><span class="p">(</span><span class="nx">@parent</span> <span class="o">and</span> <span class="nx">@parent</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> </td> </tr> <tr id="section-9"> <td class="docs"> <div class="octowrap"> <a class="octothorpe" href="#section-9">#</a> </div> <p>If we need to store an intermediate result, find an available name for a
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compiler-generated variable. <code>_a</code>, <code>_b</code>, and so on...</p> </td> <td class="code"> <div class="highlight"><pre> <span class="nv">free_variable: </span><span class="o">-></span>
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<span class="k">while</span> <span class="nx">@check</span> <span class="nx">@temp_var</span>
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<span class="nv">ordinal: </span><span class="mi">1</span> <span class="o">+</span> <span class="nb">parseInt</span> <span class="nx">@temp_var</span><span class="p">.</span><span class="nx">substr</span><span class="p">(</span><span class="mi">1</span><span class="p">),</span> <span class="mi">36</span>
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<span class="vi">@temp_var: </span><span class="s1">'_'</span> <span class="o">+</span> <span class="nx">ordinal</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="p">(</span><span class="sr">/\d/g</span><span class="p">,</span> <span class="s1">'a'</span><span class="p">)</span>
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<span class="nx">@variables</span><span class="p">[</span><span class="nx">@temp_var</span><span class="p">]</span><span class="o">:</span> <span class="s1">'var'</span>
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<span class="nx">@temp_var</span></pre></div> </td> </tr> <tr id="section-10"> <td class="docs"> <div class="octowrap"> <a class="octothorpe" href="#section-10">#</a> </div> <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).</p> </td> <td class="code"> <div class="highlight"><pre> <span class="nv">assign: </span><span class="p">(</span><span class="nx">name</span><span class="p">,</span> <span class="nx">value</span><span class="p">)</span> <span class="o">-></span>
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<span class="nx">@variables</span><span class="p">[</span><span class="nx">name</span><span class="p">]</span><span class="o">:</span> <span class="p">{</span><span class="nv">value: </span><span class="nx">value</span><span class="p">,</span> <span class="nv">assigned: </span><span class="kc">true</span><span class="p">}</span></pre></div> </td> </tr> <tr id="section-11"> <td class="docs"> <div class="octowrap"> <a class="octothorpe" href="#section-11">#</a> </div> <p>Does this scope reference any variables that need to be declared in the
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given function body?</p> </td> <td class="code"> <div class="highlight"><pre> <span class="nv">has_declarations: </span><span class="p">(</span><span class="nx">body</span><span class="p">)</span> <span class="o">-></span>
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<span class="nx">body</span> <span class="o">is</span> <span class="nx">@expressions</span> <span class="o">and</span> <span class="nx">@any</span> <span class="p">(</span><span class="nx">k</span><span class="p">,</span> <span class="nx">val</span><span class="p">)</span> <span class="o">-></span> <span class="nx">val</span> <span class="o">is</span> <span class="s1">'var'</span></pre></div> </td> </tr> <tr id="section-12"> <td class="docs"> <div class="octowrap"> <a class="octothorpe" href="#section-12">#</a> </div> <p>Does this scope reference any assignments that need to be declared at the
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top of the given function body?</p> </td> <td class="code"> <div class="highlight"><pre> <span class="nv">has_assignments: </span><span class="p">(</span><span class="nx">body</span><span class="p">)</span> <span class="o">-></span>
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<span class="nx">body</span> <span class="o">is</span> <span class="nx">@expressions</span> <span class="o">and</span> <span class="nx">@any</span> <span class="p">(</span><span class="nx">k</span><span class="p">,</span> <span class="nx">val</span><span class="p">)</span> <span class="o">-></span> <span class="nx">val</span><span class="p">.</span><span class="nx">assigned</span></pre></div> </td> </tr> <tr id="section-13"> <td class="docs"> <div class="octowrap"> <a class="octothorpe" href="#section-13">#</a> </div> <p>Return the list of variables first declared in this scope.</p> </td> <td class="code"> <div class="highlight"><pre> <span class="nv">declared_variables: </span><span class="o">-></span>
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<span class="p">(</span><span class="nx">key</span> <span class="k">for</span> <span class="nx">key</span><span class="p">,</span> <span class="nx">val</span> <span class="k">of</span> <span class="nx">@variables</span> <span class="k">when</span> <span class="nx">val</span> <span class="o">is</span> <span class="s1">'var'</span><span class="p">).</span><span class="nx">sort</span><span class="p">()</span></pre></div> </td> </tr> <tr id="section-14"> <td class="docs"> <div class="octowrap"> <a class="octothorpe" href="#section-14">#</a> </div> <p>Return the list of assignments that are supposed to be made at the top
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of this scope.</p> </td> <td class="code"> <div class="highlight"><pre> <span class="nv">assigned_variables: </span><span class="o">-></span>
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<span class="s2">"$key = $val.value"</span> <span class="k">for</span> <span class="nx">key</span><span class="p">,</span> <span class="nx">val</span> <span class="k">of</span> <span class="nx">@variables</span> <span class="k">when</span> <span class="nx">val</span><span class="p">.</span><span class="nx">assigned</span></pre></div> </td> </tr> <tr id="section-15"> <td class="docs"> <div class="octowrap"> <a class="octothorpe" href="#section-15">#</a> </div> <p>Compile the JavaScript for all of the variable declarations in this scope.</p> </td> <td class="code"> <div class="highlight"><pre> <span class="nv">compiled_declarations: </span><span class="o">-></span>
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<span class="nx">@declared_variables</span><span class="p">().</span><span class="nx">join</span> <span class="s1">', '</span></pre></div> </td> </tr> <tr id="section-16"> <td class="docs"> <div class="octowrap"> <a class="octothorpe" href="#section-16">#</a> </div> <p>Compile the JavaScript for all of the variable assignments in this scope.</p> </td> <td class="code"> <div class="highlight"><pre> <span class="nv">compiled_assignments: </span><span class="o">-></span>
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<span class="nx">@assigned_variables</span><span class="p">().</span><span class="nx">join</span> <span class="s1">', '</span>
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</pre></div> </td> </tr> </tbody> </table> </div> </body> </html> |