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| <!DOCTYPE html>  <html> <head>   <title>helpers.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="browser.html">                 browser.coffee               </a>                                           <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>               helpers.coffee             </h1>           </th>           <th class="code">           </th>         </tr>       </thead>       <tbody>                               <tr id="section-1">             <td class="docs">               <div class="pilwrap">                 <a class="pilcrow" href="#section-1">¶</a>               </div>               <p>This file contains the common helper functions that we'd like to share among
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| the <strong>Lexer</strong>, <strong>Rewriter</strong>, and the <strong>Nodes</strong>. Merge objects, flatten
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| arrays, count characters, that sort of thing.</p>             </td>             <td class="code">               <div class="highlight"><pre></pre></div>             </td>           </tr>                               <tr id="section-2">             <td class="docs">               <div class="pilwrap">                 <a class="pilcrow" href="#section-2">¶</a>               </div>               <p>Peek at the beginning of a given string to see if it matches a sequence.</p>             </td>             <td class="code">               <div class="highlight"><pre><span class="nv">exports.starts = </span><span class="p">(</span><span class="nx">string</span><span class="p">,</span> <span class="nx">literal</span><span class="p">,</span> <span class="nx">start</span><span class="p">)</span> <span class="o">-></span>
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|   <span class="nx">literal</span> <span class="o">is</span> <span class="nx">string</span><span class="p">.</span><span class="nx">substr</span> <span class="nx">start</span><span class="p">,</span> <span class="nx">literal</span><span class="p">.</span><span class="nx">length</span></pre></div>             </td>           </tr>                               <tr id="section-3">             <td class="docs">               <div class="pilwrap">                 <a class="pilcrow" href="#section-3">¶</a>               </div>               <p>Peek at the end of a given string to see if it matches a sequence.</p>             </td>             <td class="code">               <div class="highlight"><pre><span class="nv">exports.ends = </span><span class="p">(</span><span class="nx">string</span><span class="p">,</span> <span class="nx">literal</span><span class="p">,</span> <span class="nx">back</span><span class="p">)</span> <span class="o">-></span>
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|   <span class="nv">len = </span><span class="nx">literal</span><span class="p">.</span><span class="nx">length</span>
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|   <span class="nx">literal</span> <span class="o">is</span> <span class="nx">string</span><span class="p">.</span><span class="nx">substr</span> <span class="nx">string</span><span class="p">.</span><span class="nx">length</span> <span class="o">-</span> <span class="nx">len</span> <span class="o">-</span> <span class="p">(</span><span class="nx">back</span> <span class="o">or</span> <span class="mi">0</span><span class="p">),</span> <span class="nx">len</span></pre></div>             </td>           </tr>                               <tr id="section-4">             <td class="docs">               <div class="pilwrap">                 <a class="pilcrow" href="#section-4">¶</a>               </div>               <p>Trim out all falsy values from an array.</p>             </td>             <td class="code">               <div class="highlight"><pre><span class="nv">exports.compact = </span><span class="p">(</span><span class="nx">array</span><span class="p">)</span> <span class="o">-></span>
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|   <span class="nx">item</span> <span class="k">for</span> <span class="nx">item</span> <span class="k">in</span> <span class="nx">array</span> <span class="k">when</span> <span class="nx">item</span></pre></div>             </td>           </tr>                               <tr id="section-5">             <td class="docs">               <div class="pilwrap">                 <a class="pilcrow" href="#section-5">¶</a>               </div>               <p>Count the number of occurrences of a character in a string.</p>             </td>             <td class="code">               <div class="highlight"><pre><span class="nv">exports.count = </span><span class="p">(</span><span class="nx">string</span><span class="p">,</span> <span class="nx">letter</span><span class="p">)</span> <span class="o">-></span>
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|   <span class="nv">num = pos = </span><span class="mi">0</span>
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|   <span class="nx">num</span><span class="o">++</span> <span class="k">while</span> <span class="nv">pos = </span><span class="mi">1</span> <span class="o">+</span> <span class="nx">string</span><span class="p">.</span><span class="nx">indexOf</span> <span class="nx">letter</span><span class="p">,</span> <span class="nx">pos</span>
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|   <span class="nx">num</span></pre></div>             </td>           </tr>                               <tr id="section-6">             <td class="docs">               <div class="pilwrap">                 <a class="pilcrow" href="#section-6">¶</a>               </div>               <p>Merge objects, returning a fresh copy with attributes from both sides.
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| Used every time <code>Base#compile</code> is called, to allow properties in the
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| options hash to propagate down the tree without polluting other branches.</p>             </td>             <td class="code">               <div class="highlight"><pre><span class="nv">exports.merge = </span><span class="p">(</span><span class="nx">options</span><span class="p">,</span> <span class="nx">overrides</span><span class="p">)</span> <span class="o">-></span>
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|   <span class="nx">extend</span> <span class="p">(</span><span class="nx">extend</span> <span class="p">{},</span> <span class="nx">options</span><span class="p">),</span> <span class="nx">overrides</span></pre></div>             </td>           </tr>                               <tr id="section-7">             <td class="docs">               <div class="pilwrap">                 <a class="pilcrow" href="#section-7">¶</a>               </div>               <p>Extend a source object with the properties of another object (shallow copy).</p>             </td>             <td class="code">               <div class="highlight"><pre><span class="nv">extend = exports.extend = </span><span class="p">(</span><span class="nx">object</span><span class="p">,</span> <span class="nx">properties</span><span class="p">)</span> <span class="o">-></span>
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|   <span class="k">for</span> <span class="nx">all</span> <span class="nx">key</span><span class="p">,</span> <span class="nx">val</span> <span class="k">of</span> <span class="nx">properties</span>
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|     <span class="nx">object</span><span class="p">[</span><span class="nx">key</span><span class="p">]</span> <span class="o">=</span> <span class="nx">val</span>
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|   <span class="nx">object</span></pre></div>             </td>           </tr>                               <tr id="section-8">             <td class="docs">               <div class="pilwrap">                 <a class="pilcrow" href="#section-8">¶</a>               </div>               <p>Return a flattened version of an array.
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| Handy for getting a list of <code>children</code> from the nodes.</p>             </td>             <td class="code">               <div class="highlight"><pre><span class="nv">exports.flatten = flatten = </span><span class="p">(</span><span class="nx">array</span><span class="p">)</span> <span class="o">-></span>
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|   <span class="nv">flattened = </span><span class="p">[]</span>
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|   <span class="k">for</span> <span class="nx">element</span> <span class="k">in</span> <span class="nx">array</span>
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|     <span class="k">if</span> <span class="nx">element</span> <span class="k">instanceof</span> <span class="nb">Array</span>
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|       <span class="nv">flattened = </span><span class="nx">flattened</span><span class="p">.</span><span class="nx">concat</span> <span class="nx">flatten</span> <span class="nx">element</span>
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|     <span class="k">else</span>
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|       <span class="nx">flattened</span><span class="p">.</span><span class="nx">push</span> <span class="nx">element</span>
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|   <span class="nx">flattened</span></pre></div>             </td>           </tr>                               <tr id="section-9">             <td class="docs">               <div class="pilwrap">                 <a class="pilcrow" href="#section-9">¶</a>               </div>               <p>Delete a key from an object, returning the value. Useful when a node is
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| looking for a particular method in an options hash.</p>             </td>             <td class="code">               <div class="highlight"><pre><span class="nv">exports.del = </span><span class="p">(</span><span class="nx">obj</span><span class="p">,</span> <span class="nx">key</span><span class="p">)</span> <span class="o">-></span>
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|   <span class="nv">val = </span> <span class="nx">obj</span><span class="p">[</span><span class="nx">key</span><span class="p">]</span>
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|   <span class="k">delete</span> <span class="nx">obj</span><span class="p">[</span><span class="nx">key</span><span class="p">]</span>
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|   <span class="nx">val</span></pre></div>             </td>           </tr>                               <tr id="section-10">             <td class="docs">               <div class="pilwrap">                 <a class="pilcrow" href="#section-10">¶</a>               </div>               <p>Gets the last item of an array(-like) object.</p>             </td>             <td class="code">               <div class="highlight"><pre><span class="nv">exports.last = </span><span class="p">(</span><span class="nx">array</span><span class="p">,</span> <span class="nx">back</span><span class="p">)</span> <span class="o">-></span> <span class="nx">array</span><span class="p">[</span><span class="nx">array</span><span class="p">.</span><span class="nx">length</span> <span class="o">-</span> <span class="p">(</span><span class="nx">back</span> <span class="o">or</span> <span class="mi">0</span><span class="p">)</span> <span class="o">-</span> <span class="mi">1</span><span class="p">]</span>
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| 
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| </pre></div>             </td>           </tr>                </tbody>     </table>   </div> </body> </html>  | 
