<!DOCTYPE html>
<html>
<head>
<title>scope.litcoffee</title>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<meta name="viewport" content="width=device-width, target-densitydpi=160dpi, initial-scale=1.0; maximum-scale=1.0; user-scalable=0;">
<link rel="stylesheet" media="all" href="docco.css" />
</head>
<body>
<div id="container">
<div id="background"></div>
<ul id="jump_to">
<li>
<a class="large" href="javascript:void(0);">Jump To …</a>
<a class="small" href="javascript:void(0);">+</a>
<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.litcoffee
</a>
<a class="source" href="sourcemap.html">
sourcemap.litcoffee
</a>
</div>
</li>
</ul>
<ul class="sections">
<li id="title">
<div class="annotation">
<h1>scope.litcoffee</h1>
</div>
</li>
<li id="section-1">
<div class="annotation">
<div class="pilwrap ">
<a class="pilcrow" href="#section-1">¶</a>
</div>
<p>The <strong>Scope</strong> class regulates lexical scoping within CoffeeScript. As you
generate code, you create a tree of scopes in the same shape as the nested
function bodies. Each scope knows about the variables declared within it,
and has a reference to its parent enclosing scope. In this way, we know which
variables are new and need to be declared with <code>var</code>, and which are shared
with external scopes.
</p>
</div>
</li>
<li id="section-2">
<div class="annotation">
<div class="pilwrap ">
<a class="pilcrow" href="#section-2">¶</a>
</div>
<p>Import the helpers we plan to use.
</p>
</div>
<div class="content"><div class='highlight'><pre>
{extend, last} = require <span class="string">'./helpers'</span>
exports.Scope = <span class="class"><span class="keyword">class</span> <span class="title">Scope</span></span></pre></div></div>
</li>
<li id="section-3">
<div class="annotation">
<div class="pilwrap ">
<a class="pilcrow" href="#section-3">¶</a>
</div>
<p>The <code>root</code> is the top-level <strong>Scope</strong> object for a given file.
</p>
</div>
<div class="content"><div class='highlight'><pre>
<span class="property">@root</span>: <span class="literal">null</span></pre></div></div>
</li>
<li id="section-4">
<div class="annotation">
<div class="pilwrap ">
<a class="pilcrow" href="#section-4">¶</a>
</div>
<p>Initialize a scope with its parent, for lookups up the chain,
as well as a reference to the <strong>Block</strong> node it belongs to, which is
where it should declare its variables, and a reference to the function that
it belongs to.
</p>
</div>
<div class="content"><div class='highlight'><pre>
constructor: (<span class="property">@parent</span>, <span class="property">@expressions</span>, <span class="property">@method</span>) ->
<span class="property">@variables</span> = [{name: <span class="string">'arguments'</span>, type: <span class="string">'arguments'</span>}]
<span class="property">@positions</span> = {}
Scope.root = <span class="keyword">this</span> <span class="keyword">unless</span> <span class="property">@parent</span></pre></div></div>
</li>
<li id="section-5">
<div class="annotation">
<div class="pilwrap ">
<a class="pilcrow" href="#section-5">¶</a>
</div>
<p>Adds a new variable or overrides an existing one.
</p>
</div>
<div class="content"><div class='highlight'><pre>
add: (name, type, immediate) ->
<span class="keyword">return</span> <span class="property">@parent</span>.add name, type, immediate <span class="keyword">if</span> <span class="property">@shared</span> <span class="keyword">and</span> <span class="keyword">not</span> immediate
<span class="keyword">if</span> Object::hasOwnProperty.call <span class="property">@positions</span>, name
<span class="property">@variables</span>[<span class="property">@positions</span>[name]].type = type
<span class="keyword">else</span>
<span class="property">@positions</span>[name] = <span class="property">@variables</span>.push({name, type}) - <span class="number">1</span></pre></div></div>
</li>
<li id="section-6">
<div class="annotation">
<div class="pilwrap ">
<a class="pilcrow" href="#section-6">¶</a>
</div>
<p>When <code>super</code> is called, we need to find the name of the current method we're
in, so that we know how to invoke the same method of the parent class. This
can get complicated if super is being called from an inner function.
<code>namedMethod</code> will walk up the scope tree until it either finds the first
function object that has a name filled in, or bottoms out.
</p>
</div>
<div class="content"><div class='highlight'><pre>
namedMethod: ->
<span class="keyword">return</span> <span class="property">@method</span> <span class="keyword">if</span> <span class="property">@method</span>?.name <span class="keyword">or</span> !<span class="property">@parent</span>
<span class="property">@parent</span>.namedMethod()</pre></div></div>
</li>
<li id="section-7">
<div class="annotation">
<div class="pilwrap ">
<a class="pilcrow" href="#section-7">¶</a>
</div>
<p>Look up a variable name in lexical scope, and declare it if it does not
already exist.
</p>
</div>
<div class="content"><div class='highlight'><pre>
find: (name) ->
<span class="keyword">return</span> <span class="literal">yes</span> <span class="keyword">if</span> <span class="property">@check</span> name
<span class="property">@add</span> name, <span class="string">'var'</span>
<span class="literal">no</span></pre></div></div>
</li>
<li id="section-8">
<div class="annotation">
<div class="pilwrap ">
<a class="pilcrow" href="#section-8">¶</a>
</div>
<p>Reserve a variable name as originating from a function parameter for this
scope. No <code>var</code> required for internal references.
</p>
</div>
<div class="content"><div class='highlight'><pre>
parameter: (name) ->
<span class="keyword">return</span> <span class="keyword">if</span> <span class="property">@shared</span> <span class="keyword">and</span> <span class="property">@parent</span>.check name, <span class="literal">yes</span>
<span class="property">@add</span> name, <span class="string">'param'</span></pre></div></div>
</li>
<li id="section-9">
<div class="annotation">
<div class="pilwrap ">
<a class="pilcrow" href="#section-9">¶</a>
</div>
<p>Just check to see if a variable has already been declared, without reserving,
walks up to the root scope.
</p>
</div>
<div class="content"><div class='highlight'><pre>
check: (name) ->
!!(<span class="property">@type</span>(name) <span class="keyword">or</span> <span class="property">@parent</span>?.check(name))</pre></div></div>
</li>
<li id="section-10">
<div class="annotation">
<div class="pilwrap ">
<a class="pilcrow" href="#section-10">¶</a>
</div>
<p>Generate a temporary variable name at the given index.
</p>
</div>
<div class="content"><div class='highlight'><pre>
temporary: (name, index) ->
<span class="keyword">if</span> name.length > <span class="number">1</span>
<span class="string">'_'</span> + name + <span class="keyword">if</span> index > <span class="number">1</span> <span class="keyword">then</span> index - <span class="number">1</span> <span class="keyword">else</span> <span class="string">''</span>
<span class="keyword">else</span>
<span class="string">'_'</span> + (index + parseInt name, <span class="number">36</span>).toString(<span class="number">36</span>).replace <span class="regexp">/\d/g</span>, <span class="string">'a'</span></pre></div></div>
</li>
<li id="section-11">
<div class="annotation">
<div class="pilwrap ">
<a class="pilcrow" href="#section-11">¶</a>
</div>
<p>Gets the type of a variable.
</p>
</div>
<div class="content"><div class='highlight'><pre>
type: (name) ->
<span class="keyword">return</span> v.type <span class="keyword">for</span> v <span class="keyword">in</span> <span class="property">@variables</span> <span class="keyword">when</span> v.name <span class="keyword">is</span> name
<span class="literal">null</span></pre></div></div>
</li>
<li id="section-12">
<div class="annotation">
<div class="pilwrap ">
<a class="pilcrow" href="#section-12">¶</a>
</div>
<p>If we need to store an intermediate result, find an available name for a
compiler-generated variable. <code>_var</code>, <code>_var2</code>, and so on...
</p>
</div>
<div class="content"><div class='highlight'><pre>
freeVariable: (name, reserve=<span class="literal">true</span>) ->
index = <span class="number">0</span>
index++ <span class="keyword">while</span> <span class="property">@check</span>((temp = <span class="property">@temporary</span> name, index))
<span class="property">@add</span> temp, <span class="string">'var'</span>, <span class="literal">yes</span> <span class="keyword">if</span> reserve
temp</pre></div></div>
</li>
<li id="section-13">
<div class="annotation">
<div class="pilwrap ">
<a class="pilcrow" href="#section-13">¶</a>
</div>
<p>Ensure that an assignment is made at the top of this scope
(or at the top-level scope, if requested).
</p>
</div>
<div class="content"><div class='highlight'><pre>
assign: (name, value) ->
<span class="property">@add</span> name, {value, assigned: <span class="literal">yes</span>}, <span class="literal">yes</span>
<span class="property">@hasAssignments</span> = <span class="literal">yes</span></pre></div></div>
</li>
<li id="section-14">
<div class="annotation">
<div class="pilwrap ">
<a class="pilcrow" href="#section-14">¶</a>
</div>
<p>Does this scope have any declared variables?
</p>
</div>
<div class="content"><div class='highlight'><pre>
hasDeclarations: ->
!!<span class="property">@declaredVariables</span>().length</pre></div></div>
</li>
<li id="section-15">
<div class="annotation">
<div class="pilwrap ">
<a class="pilcrow" href="#section-15">¶</a>
</div>
<p>Return the list of variables first declared in this scope.
</p>
</div>
<div class="content"><div class='highlight'><pre>
declaredVariables: ->
realVars = []
tempVars = []
<span class="keyword">for</span> v <span class="keyword">in</span> <span class="property">@variables</span> <span class="keyword">when</span> v.type <span class="keyword">is</span> <span class="string">'var'</span>
(<span class="keyword">if</span> v.name.charAt(<span class="number">0</span>) <span class="keyword">is</span> <span class="string">'_'</span> <span class="keyword">then</span> tempVars <span class="keyword">else</span> realVars).push v.name
realVars.sort().concat tempVars.sort()</pre></div></div>
</li>
<li id="section-16">
<div class="annotation">
<div class="pilwrap ">
<a class="pilcrow" href="#section-16">¶</a>
</div>
<p>Return the list of assignments that are supposed to be made at the top
of this scope.
</p>
</div>
<div class="content"><div class='highlight'><pre>
assignedVariables: ->
<span class="string">"<span class="subst">#{v.name}</span> = <span class="subst">#{v.type.value}</span>"</span> <span class="keyword">for</span> v <span class="keyword">in</span> <span class="property">@variables</span> <span class="keyword">when</span> v.type.assigned</pre></div></div>
</li>
</ul>
</div>
</body>
</html>
