From 094b198d5d53156caebf0e7e127058fc7d3c1912 Mon Sep 17 00:00:00 2001 From: Jeremy Ashkenas Date: Sun, 7 Mar 2010 16:41:06 -0500 Subject: [PATCH] first little bit of commenting the nodes.coffee -- with some slight refactors --- documentation/docs/nodes.html | 198 ++++++++++++++------------- lib/nodes.js | 249 ++++++++++++++++++---------------- src/nodes.coffee | 207 +++++++++++++++------------- test/test_expressions.coffee | 2 +- 4 files changed, 351 insertions(+), 305 deletions(-) diff --git a/documentation/docs/nodes.html b/documentation/docs/nodes.html index fb709ccc..40fc487b 100644 --- a/documentation/docs/nodes.html +++ b/documentation/docs/nodes.html @@ -1,109 +1,108 @@ - nodes.coffee

nodes.coffee

# 
if process?
+      nodes.coffee           
     
                      push: (arg)->@args.push(arg)@children.push(arg)
-    thiscode: arg.compileocode: ifarginstanceofSplatNodethencodeelse"[$code]"ifiis0thencodeelse".concat($code)"
-    "$@prefix$meth.apply($obj, ${ args.join('') })"        '''constructor: (child,parent)->
-    @children: [@child: child,@parent: parent]intro: "($@from_var <= $@to_var ? $idx"compare: "$intro <$equals $@to_var : $idx >$equals $@to_var)"incr: "$intro += $step : $idx -= $step)"
-    "$vars; $compare; $incr"return@compile_assignment(o)if@ASSIGNMENT.indexOf(@operator)>=0return@compile_unary(o)if@is_unary()return@compile_existence(o)if@operatoris'?'
-    [@first.compile(o),@operator,@second.compile(o)].join' 'space: if@PREFIX_OPERATORS.indexOf(@operator)>=0then' 'else''parts: [@operator,space,@first.compile(o)]parts: parts.reverse()if@flip
-    parts.join('')finally_part: (@ensureor'')and' finally {\n'+@ensure.compile(merge(o,{returns: null}))+"\n${@idt()}}""${@idt()}try {\n$attempt_part\n${@idt()}}$catch_part$finally_part"
 
-statementTryNodecompile_node: (o)->"${@idt()}throw ${@expression.compile(o)};"
 
-statementThrowNode,trueifvariableinstanceofCallNodeor(variableinstanceofValueNodeandvariable.has_properties())[first,second]:variable.compile_reference(o)[first,second]:[first.compile(o),second.compile(o)]
-  "(typeof $first !== \"undefined\" && $second !== null)"returncodeif@is_statement()l: code.lengthcode: code.substr(o,l-1)ifcode.substr(l-1,1)is';'
-    "($code)"close: if@objectthen'}}\n'else'}\n'"$set_result${source_part}for ($for_part) {\n$var_part$body\n${@idt()}$close${@idt()}$return_result"
 
-statementForNode
                
                        
               nodes.coffee             
           		                               
                                             
                            
                 #               
               
nodes.coffee contains all of the node classes for the syntax tree. Most
+nodes are created as the result of actions in the grammar,
+but some are created by other nodes as a method of code generation. To convert
+the syntax tree into a string of JavaScript code, call compile() on the root.
             		                            
             		           
                               
                            
                 #               
               
Set up for both Node.js and the browser, by
+including the Scope class.
             		                            
if process?
   process.mixin require 'scope'
 else
-  this.exports: this
             		           
                               
                            
                 #               
               
Some helper functions
             		                            
             		           
                               
                            
                 #               
               
Tabs are two spaces for pretty printing.
             		                            
TAB: '  '
-TRAILING_WHITESPACE: /\s+$/gm
             		           
                               
                            
                 #               
               
Keep the identifier regex in sync with the Lexer.
             		                            
IDENTIFIER:   /^[a-zA-Z$_](\w|\$)*$/
             		           
                               
                            
                 #               
               
Merge objects.
             		                            
merge: (options, overrides) ->
-  fresh: {}
-  (fresh[key]: val) for key, val of options
-  (fresh[key]: val) for key, val of overrides if overrides
-  fresh
             		           
                               
                            
                 #               
               
Trim out all falsy values from an array.
             		                            
compact: (array) -> item for item in array when item
             		           
                               
                            
                 #               
               
Return a completely flattened version of an array.
             		                            
flatten: (array) ->
-  memo: []
-  for item in array
-    if item instanceof Array then memo: memo.concat(item) else memo.push(item)
-  memo
             		           
                               
                            
                 #               
               
Delete a key from an object, returning the value.
             		                            
del: (obj, key) ->
-  val: obj[key]
-  delete obj[key]
-  val
             		           
                               
                            
                 #               
               
Quickie helper for a generated LiteralNode.
             		                            
literal: (name) ->
-  new LiteralNode(name)
             		           
                               
                            
                 #               
               
Mark a node as a statement, or a statement only.
             		                            
statement: (klass, only) ->
+  this.exports: this
             		           
                               
                            
                 #               
               
Helper function that marks a node as a JavaScript statement, or as a
+pure_statement. Statements must be wrapped in a closure when used as an
+expression, and nodes tagged as pure_statement cannot be closure-wrapped
+without losing their meaning.
             		                            
statement: (klass, only) ->
   klass::is_statement: -> true
-  (klass::is_statement_only: -> true) if only
             		           
                               
                            
                 #               
               
The abstract base class for all CoffeeScript nodes.
-All nodes are implement a "compile_node" method, which performs the
-code generation for that node. To compile a node, call the "compile"
-method, which wraps "compile_node" in some extra smarts, to know when the
-generated code should be wrapped up in a closure. An options hash is passed
-and cloned throughout, containing messages from higher in the AST,
-information about the current scope, and indentation level.
             		                            
exports.BaseNode: class BaseNode
             		           
                               
                            
                 #               
               
This is extremely important -- we convert JS statements into expressions
-by wrapping them in a closure, only if it's possible, and we're not at
+  (klass::is_pure_statement: -> true) if only             
           
                               
                            
                 #               
               
The BaseNode is the abstract base class for all nodes in the syntax tree.
+Each subclass implements the compile_node method, which performs the
+code generation for that node. To compile a node to JavaScript,
+call compile on it, which wraps compile_node in some generic extra smarts,
+to know when the generated code needs to be wrapped up in a closure.
+An options hash is passed and cloned throughout, containing information about
+the environment from higher in the tree (such as if a returned value is
+being requested by the surrounding function), information about the current
+scope, and indentation level.
             		                            
exports.BaseNode: class BaseNode
             		           
                               
                            
                 #               
               
Common logic for determining whether to wrap this node in a closure before
+compiling it, or to compile directly. We need to wrap if this node is a
+statement, and it's not a pure_statement, and we're not at
 the top level of a block (which would be unnecessary), and we haven't
-already been asked to return the result.
             		                            
  compile: (o) ->
+already been asked to return the result (because statements know how to
+return results).
             
                            
  compile: (o) ->
     @options: merge o or {}
     @indent:  o.indent
     del @options, 'operation' unless @operation_sensitive()
     top:      if @top_sensitive() then @options.top else del @options, 'top'
-    closure:  @is_statement() and not @is_statement_only() and not top and
+    closure:  @is_statement() and not @is_pure_statement() and not top and
               not @options.returns and not (this instanceof CommentNode) and
-              not @contains (node) -> node.is_statement_only()
-    if closure then @compile_closure(@options) else @compile_node(@options)
             		           
                               
                            
                 #               
               
Statements converted into expressions share scope with their parent
-closure, to preserve JavaScript-style lexical scope.
             		                            
  compile_closure: (o) ->
+              not @contains (node) -> node.is_pure_statement()
+    if closure then @compile_closure(@options) else @compile_node(@options)
             		           
                               
                            
                 #               
               
Statements converted into expressions via closure-wrapping share a scope
+object with their parent closure, to preserve the expected lexical scope.
             		                            
  compile_closure: (o) ->
     @indent: o.indent
     o.shared_scope: o.scope
-    ClosureNode.wrap(this).compile(o)
             		           
                               
                            
                 #               
               
If the code generation wishes to use the result of a complex expression
-in multiple places, ensure that the expression is only ever evaluated once.
             		                            
  compile_reference: (o) ->
+    ClosureNode.wrap(this).compile(o)
             		           
                               
                            
                 #               
               
If the code generation wishes to use the result of a complex expression
+in multiple places, ensure that the expression is only ever evaluated once,
+by assigning it to a temporary variable.
             		                            
  compile_reference: (o) ->
     reference: literal(o.scope.free_variable())
     compiled:  new AssignNode(reference, this)
-    [compiled, reference]
             		           
                               
                            
                 #               
               
Quick short method for the current indentation level, plus tabbing in.
             		                            
  idt: (tabs) ->
+    [compiled, reference]
             		           
                               
                            
                 #               
               
Quick short method for the current indentation level, plus tabbing in.
             		                            
  idt: (tabs) ->
     idt: (@indent || '')
     idt += TAB for i in [0...(tabs or 0)]
-    idt
             		           
                               
                            
                 #               
               
Does this node, or any of its children, contain a node of a certain kind?
             		                            
  contains: (block) ->
+    idt
             		           
                               
                            
                 #               
               
Does this node, or any of its children, contain a node of a certain kind?
             		                            
  contains: (block) ->
     for node in @children
       return true if block(node)
       return true if node.contains and node.contains block
-    false
             		           
                               
                            
                 #               
               
Perform an in-order traversal of the AST.
             		                            
  traverse: (block) ->
+    false
             		           
                               
                            
                 #               
               
Perform an in-order traversal of the AST.
             		                            
  traverse: (block) ->
     for node in @children
       block node
-      node.traverse block if node.traverse
             		           
                               
                            
                 #               
               
toString representation of the node, for inspecting the parse tree.
             		                            
  toString: (idt) ->
+      node.traverse block if node.traverse
             		           
                               
                            
                 #               
               
toString representation of the node, for inspecting the parse tree.
             		                            
  toString: (idt) ->
     idt ||= ''
-    '\n' + idt + @type + (child.toString(idt + TAB) for child in @children).join('')
             		           
                               
                            
                 #               
               
Default implementations of the common node methods.
             		                            
  unwrap:               -> this
+    '\n' + idt + @type + (child.toString(idt + TAB) for child in @children).join('')
             		           
                               
                            
                 #               
               
Default implementations of the common node methods.
             		                            
  unwrap:               -> this
   children:             []
   is_statement:         -> false
-  is_statement_only:    -> false
+  is_pure_statement:    -> false
   top_sensitive:        -> false
-  operation_sensitive:  -> false
             		           
                               
                            
                 #               
               
A collection of nodes, each one representing an expression.
             		                            
exports.Expressions: class Expressions extends BaseNode
+  operation_sensitive:  -> false
             		           
                               
                            
                 #               
               
A collection of nodes, each one representing an expression.
             		                            
exports.Expressions: class Expressions extends BaseNode
   type: 'Expressions'
 
   constructor: (nodes) ->
-    @children: @expressions: compact flatten nodes or []
             		           
                               
                            
                 #               
               
Tack an expression on to the end of this expression list.
             		                            
  push: (node) ->
+    @children: @expressions: compact flatten nodes or []
             		           
                               
                            
                 #               
               
Tack an expression on to the end of this expression list.
             		                            
  push: (node) ->
     @expressions.push(node)
-    this
             		           
                               
                            
                 #               
               
Tack an expression on to the beginning of this expression list.
             		                            
  unshift: (node) ->
+    this
             		           
                               
                            
                 #               
               
Tack an expression on to the beginning of this expression list.
             		                            
  unshift: (node) ->
     @expressions.unshift(node)
-    this
             		           
                               
                            
                 #               
               
If this Expressions consists of a single node, pull it back out.
             		                            
  unwrap: ->
-    if @expressions.length is 1 then @expressions[0] else this
             		           
                               
                            
                 #               
               
Is this an empty block of code?
             		                            
  empty: ->
-    @expressions.length is 0
             		           
                               
                            
                 #               
               
Is the node last in this block of expressions?
             		                            
  is_last: (node) ->
+    this
             		           
                               
                            
                 #               
               
If this Expressions consists of a single node, pull it back out.
             		                            
  unwrap: ->
+    if @expressions.length is 1 then @expressions[0] else this
             		           
                               
                            
                 #               
               
Is this an empty block of code?
             		                            
  empty: ->
+    @expressions.length is 0
             		           
                               
                            
                 #               
               
Is the node last in this block of expressions?
             		                            
  is_last: (node) ->
     l: @expressions.length
     last_index: if @expressions[l - 1] instanceof CommentNode then 2 else 1
     node is @expressions[l - last_index]
 
   compile: (o) ->
     o ||= {}
-    if o.scope then super(o) else @compile_root(o)
             		           
                               
                            
                 #               
               
Compile each expression in the Expressions body.
             		                            
  compile_node: (o) ->
-    (@compile_expression(node, merge(o)) for node in @expressions).join("\n")
             		           
                               
                            
                 #               
               
If this is the top-level Expressions, wrap everything in a safety closure.
             		                            
  compile_root: (o) ->
+    if o.scope then super(o) else @compile_root(o)
             		           
                               
                            
                 #               
               
Compile each expression in the Expressions body.
             		                            
  compile_node: (o) ->
+    (@compile_expression(node, merge(o)) for node in @expressions).join("\n")
             		           
                               
                            
                 #               
               
If this is the top-level Expressions, wrap everything in a safety closure.
             		                            
  compile_root: (o) ->
     o.indent: @indent: indent: if o.no_wrap then '' else TAB
     o.scope: new Scope(null, this, null)
     code: if o.globals then @compile_node(o) else @compile_with_declarations(o)
     code: code.replace(TRAILING_WHITESPACE, '')
-    if o.no_wrap then code else "(function(){\n$code\n})();\n"
             		           
                               
                            
                 #               
               
Compile the expressions body, with declarations of all inner variables
+    if o.no_wrap then code else "(function(){\n$code\n})();\n"             
           
                               
                            
                 #               
               
Compile the expressions body, with declarations of all inner variables
 pushed up to the top.
             		                            
  compile_with_declarations: (o) ->
     code: @compile_node(o)
     args: @contains (node) -> node instanceof ValueNode and node.is_arguments()
     code: "${@idt()}arguments = Array.prototype.slice.call(arguments, 0);\n$code" if args
     code: "${@idt()}var ${o.scope.compiled_assignments()};\n$code"  if o.scope.has_assignments(this)
     code: "${@idt()}var ${o.scope.compiled_declarations()};\n$code" if o.scope.has_declarations(this)
-    code
             		           
                               
                            
                 #               
               
Compiles a single expression within the expressions body.
             		                            
  compile_expression: (node, o) ->
+    code
             		           
                               
                            
                 #               
               
Compiles a single expression within the expressions body.
             		                            
  compile_expression: (node, o) ->
     @indent: o.indent
-    stmt:    node.is_statement()
             		           
                               
                            
                 #               
               
We need to return the result if this is the last node in the expressions body.
             		                            
    returns: del(o, 'returns') and @is_last(node) and not node.is_statement_only()
             		           
                               
                            
                 #               
               
Return the regular compile of the node, unless we need to return the result.
             		                            
    return (if stmt then '' else @idt()) + node.compile(merge(o, {top: true})) + (if stmt then '' else ';') unless returns
             		           
                               
                            
                 #               
               
If it's a statement, the node knows how to return itself.
             		                            
    return node.compile(merge(o, {returns: true})) if node.is_statement()
             		           
                               
                            
                 #               
               
Otherwise, we can just return the value of the expression.
             		                            
    return "${@idt()}return ${node.compile(o)};"
             		           
                               
                            
                 #               
               
Wrap up a node as an Expressions, unless it already is one.
             		                            
Expressions.wrap: (nodes) ->
+    stmt:    node.is_statement()
             		           
                               
                            
                 #               
               
We need to return the result if this is the last node in the expressions body.
             		                            
    returns: del(o, 'returns') and @is_last(node) and not node.is_pure_statement()
             		           
                               
                            
                 #               
               
Return the regular compile of the node, unless we need to return the result.
             		                            
    return (if stmt then '' else @idt()) + node.compile(merge(o, {top: true})) + (if stmt then '' else ';') unless returns
             		           
                               
                            
                 #               
               
If it's a statement, the node knows how to return itself.
             		                            
    return node.compile(merge(o, {returns: true})) if node.is_statement()
             		           
                               
                            
                 #               
               
Otherwise, we can just return the value of the expression.
             		                            
    return "${@idt()}return ${node.compile(o)};"
             		           
                               
                            
                 #               
               
Wrap up a node as an Expressions, unless it already is one.
             		                            
Expressions.wrap: (nodes) ->
   return nodes[0] if nodes.length is 1 and nodes[0] instanceof Expressions
   new Expressions(nodes)
 
-statement Expressions
             		           
                               
                            
                 #               
               
Literals are static values that can be passed through directly into
+statement Expressions             
           
                               
                            
                 #               
               
Literals are static values that can be passed through directly into
 JavaScript without translation, eg.: strings, numbers, true, false, null...
             		                            
exports.LiteralNode: class LiteralNode extends BaseNode
   type: 'Literal'
 
   constructor: (value) ->
-    @value: value
             		           
                               
                            
                 #               
               
Break and continue must be treated as statements -- they lose their meaning
+    @value: value             
           
                               
                            
                 #               
               
Break and continue must be treated as statements -- they lose their meaning
 when wrapped in a closure.
             		                            
  is_statement: ->
     @value is 'break' or @value is 'continue'
 
-  is_statement_only: LiteralNode::is_statement
+  is_pure_statement: LiteralNode::is_statement
 
   compile_node: (o) ->
     idt: if @is_statement() then @idt() else ''
@@ -111,7 +110,7 @@ when wrapped in a closure.
             
             
     "$idt$@value$end"
 
   toString: (idt) ->
-    " \"$@value\""                        
                               
                            
                 #               
               
Return an expression, or wrap it in a closure and return it.
             		                            
exports.ReturnNode: class ReturnNode extends BaseNode
+    " \"$@value\""
             		           
                               
                            
                 #               
               
Return an expression, or wrap it in a closure and return it.
             		                            
exports.ReturnNode: class ReturnNode extends BaseNode
   type: 'Return'
 
   constructor: (expression) ->
@@ -121,7 +120,7 @@ when wrapped in a closure.
             
             
     return @expression.compile(merge(o, {returns: true})) if @expression.is_statement()
     "${@idt()}return ${@expression.compile(o)};"
 
-statement ReturnNode, true                        
                               
                            
                 #               
               
A value, indexed or dotted into, or vanilla.
             		                            
exports.ValueNode: class ValueNode extends BaseNode
+statement ReturnNode, true
             		           
                               
                            
                 #               
               
A value, indexed or dotted into, or vanilla.
             		                            
exports.ValueNode: class ValueNode extends BaseNode
   type: 'Value'
 
   SOAK: " == undefined ? undefined : "
@@ -153,7 +152,7 @@ when wrapped in a closure.
             
             
     @base.value is 'arguments'
 
   unwrap: ->
-    if @properties.length then this else @base                        
                               
                            
                 #               
               
Values are statements if their base is a statement.
             		                            
  is_statement: ->
+    if @properties.length then this else @base
             		           
                               
                            
                 #               
               
Values are statements if their base is a statement.
             		                            
  is_statement: ->
     @base.is_statement and @base.is_statement() and not @has_properties()
 
   compile_node: (o) ->
@@ -180,7 +179,7 @@ when wrapped in a closure.
             
             
         complete += part
         @last: part
 
-    if op and soaked then "($complete)" else complete                        
                               
                            
                 #               
               
Pass through CoffeeScript comments into JavaScript comments at the
+    if op and soaked then "($complete)" else complete             
           
                               
                            
                 #               
               
Pass through CoffeeScript comments into JavaScript comments at the
 same position.
             		                            
exports.CommentNode: class CommentNode extends BaseNode
   type: 'Comment'
 
@@ -191,7 +190,7 @@ same position.
             
             
   compile_node: (o) ->
     "${@idt()}//" + @lines.join("\n${@idt()}//")
 
-statement CommentNode                        
                               
                            
                 #               
               
Node for a function invocation. Takes care of converting super() calls into
+statement CommentNode             
           
                               
                            
                 #               
               
Node for a function invocation. Takes care of converting super() calls into
 calls against the prototype's function of the same name.
             		                            
exports.CallNode: class CallNode extends BaseNode
   type: 'Call'
 
@@ -206,17 +205,17 @@ calls against the prototype's function of the same name.
             

    
     
                             
                               
                            
                 #               
               
Compile a vanilla function call.
             		                            
  compile_node: (o) ->
+    this
             		           
                               
                            
                 #               
               
Compile a vanilla function call.
             		                            
  compile_node: (o) ->
     return @compile_splat(o) if @args[@args.length - 1] instanceof SplatNode
     args: (arg.compile(o) for arg in @args).join(', ')
     return @compile_super(args, o) if @variable is 'super'
-    "$@prefix${@variable.compile(o)}($args)"
             		           
                               
                            
                 #               
               
Compile a call against the superclass's implementation of the current function.
             		                            
  compile_super: (args, o) ->
+    "$@prefix${@variable.compile(o)}($args)"
             		           
                               
                            
                 #               
               
Compile a call against the superclass's implementation of the current function.
             		                            
  compile_super: (args, o) ->
     methname: o.scope.method.name
     meth: if o.scope.method.proto
       "${o.scope.method.proto}.__superClass__.$methname"
     else
       "$methname.__superClass__.constructor"
-    "$meth.call(this${ if args.length then ', ' else '' }$args)"
             		           
                               
                            
                 #               
               
Compile a function call being passed variable arguments.
             		                            
  compile_splat: (o) ->
+    "$meth.call(this${ if args.length then ', ' else '' }$args)"
             		           
                               
                            
                 #               
               
Compile a function call being passed variable arguments.
             		                            
  compile_splat: (o) ->
     meth: @variable.compile o
     obj:  @variable.source or 'this'
     if obj.match(/\(/)
@@ -227,7 +226,7 @@ calls against the prototype's function of the same name.
             

        
              
                                      
                               
                            
                 #               
               
Node to extend an object's prototype with an ancestor object.
+    "$@prefix$meth.apply($obj, ${ args.join('') })"             
           
                               
                            
                 #               
               
Node to extend an object's prototype with an ancestor object.
 After goog.inherits from the Closure Library.
             		                            
exports.ExtendsNode: class ExtendsNode extends BaseNode
   type: 'Extends'
 
@@ -242,11 +241,11 @@ After goog.inherits from the Closure Library.
             

 
 
                               
                               
                            
                 #               
               
Hooking one constructor into another's prototype chain.
             		                            
  compile_node: (o) ->
+    @children:  [@child: child, @parent: parent]
             		           
                               
                            
                 #               
               
Hooking one constructor into another's prototype chain.
             		                            
  compile_node: (o) ->
     o.scope.assign('__extends', @code, true)
     ref:  new ValueNode literal('__extends')
     call: new CallNode ref, [@child, @parent]
-    call.compile(o)
             		           
                               
                            
                 #               
               
A dotted accessor into a part of a value, or the :: shorthand for
+    call.compile(o)             
           
                               
                            
                 #               
               
A dotted accessor into a part of a value, or the :: shorthand for
 an accessor into the object's prototype.
             		                            
exports.AccessorNode: class AccessorNode extends BaseNode
   type: 'Accessor'
 
@@ -257,7 +256,7 @@ an accessor into the object's prototype.
             
             this
 
   compile_node: (o) ->
-    '.' + (if @prototype then 'prototype.' else '') + @name.compile(o)                        
                               
                            
                 #               
               
An indexed accessor into a part of an array or object.
             		                            
exports.IndexNode: class IndexNode extends BaseNode
+    '.' + (if @prototype then 'prototype.' else '') + @name.compile(o)
             		           
                               
                            
                 #               
               
An indexed accessor into a part of an array or object.
             		                            
exports.IndexNode: class IndexNode extends BaseNode
   type: 'Index'
 
   constructor: (index, tag) ->
@@ -266,7 +265,7 @@ an accessor into the object's prototype.
             
             compile_node: (o) ->
     idx: @index.compile o
-    "[$idx]"                        
                               
                            
                 #               
               
A range literal. Ranges can be used to extract portions (slices) of arrays,
+    "[$idx]"             
           
                               
                            
                 #               
               
A range literal. Ranges can be used to extract portions (slices) of arrays,
 or to specify a range for list comprehensions.
             		                            
exports.RangeNode: class RangeNode extends BaseNode
   type: 'Range'
 
@@ -290,13 +289,13 @@ or to specify a range for list comprehensions.
             

        
      
                                 
                               
                            
                 #               
               
Expand the range into the equivalent array, if it's not being used as
+    "$vars; $compare; $incr"             
           
                               
                            
                 #               
               
Expand the range into the equivalent array, if it's not being used as
 part of a comprehension, slice, or splice.
 TODO: This generates pretty ugly code ... shrink it.
             		                            
  compile_array: (o) ->
     name: o.scope.free_variable()
     body: Expressions.wrap([literal(name)])
     arr:  Expressions.wrap([new ForNode(body, {source: (new ValueNode(this))}, literal(name))])
-    (new ParentheticalNode(new CallNode(new CodeNode([], arr)))).compile(o)
             		           
                               
                            
                 #               
               
An array slice literal. Unlike JavaScript's Array#slice, the second parameter
+    (new ParentheticalNode(new CallNode(new CodeNode([], arr)))).compile(o)             
           
                               
                            
                 #               
               
An array slice literal. Unlike JavaScript's Array#slice, the second parameter
 specifies the index of the end of the slice (just like the first parameter)
 is the index of the beginning.
             		                            
exports.SliceNode: class SliceNode extends BaseNode
   type: 'Slice'
@@ -309,11 +308,11 @@ is the index of the beginning.
             
             from:       @range.from.compile(o)
     to:         @range.to.compile(o)
     plus_part:  if @range.exclusive then '' else ' + 1'
-    ".slice($from, $to$plus_part)"                        
                               
                            
                 #               
               
An object literal.
             		                            
exports.ObjectNode: class ObjectNode extends BaseNode
+    ".slice($from, $to$plus_part)"
             		           
                               
                            
                 #               
               
An object literal.
             		                            
exports.ObjectNode: class ObjectNode extends BaseNode
   type: 'Object'
 
   constructor: (props) ->
-    @children: @objects: @properties: props or []
             		           
                               
                            
                 #               
               
All the mucking about with commas is to make sure that CommentNodes and
+    @children: @objects: @properties: props or []             
           
                               
                            
                 #               
               
All the mucking about with commas is to make sure that CommentNodes and
 AssignNodes get interleaved correctly, with no trailing commas or
 commas affixed to comments. TODO: Extract this and add it to ArrayNode.
             		                            
  compile_node: (o) ->
     o.indent: @idt(1)
@@ -327,7 +326,7 @@ commas affixed to comments. TODO: Extract this and add it to ArrayNode.

       indent + prop.compile(o) + join
     props: props.join('')
     inner: if props then '\n' + props + '\n' + @idt() else ''
-    "{$inner}"
             		           
                               
                            
                 #               
               
A class literal, including optional superclass and constructor.
             		                            
exports.ClassNode: class ClassNode extends BaseNode
+    "{$inner}"
             		           
                               
                            
                 #               
               
A class literal, including optional superclass and constructor.
             		                            
exports.ClassNode: class ClassNode extends BaseNode
   type: 'Class'
 
   constructor: (variable, parent, props) ->
@@ -366,7 +365,7 @@ commas affixed to comments. TODO: Extract this and add it to ArrayNode.

     returns:   if ret           then '\n' + @idt() + 'return ' + @variable.compile(o) + ';' else ''
     "$construct$extension$props$returns"
 
-statement ClassNode
             		           
                               
                            
                 #               
               
An array literal.
             		                            
exports.ArrayNode: class ArrayNode extends BaseNode
+statement ClassNode
             		           
                               
                            
                 #               
               
An array literal.
             		                            
exports.ArrayNode: class ArrayNode extends BaseNode
   type: 'Array'
 
   constructor: (objects) ->
@@ -384,24 +383,24 @@ commas affixed to comments. TODO: Extract this and add it to ArrayNode.

         "$code, "
     objects: objects.join('')
     ending: if objects.indexOf('\n') >= 0 then "\n${@idt()}]" else ']'
-    "[$objects$ending"
             		           
                               
                            
                 #               
               
A faux-node that is never created by the grammar, but is used during
+    "[$objects$ending"             
           
                               
                            
                 #               
               
A faux-node that is never created by the grammar, but is used during
 code generation to generate a quick "array.push(value)" tree of nodes.
             		                            
PushNode: exports.PushNode: {
 
   wrap: (array, expressions) ->
     expr: expressions.unwrap()
-    return expressions if expr.is_statement_only() or expr.contains (n) -> n.is_statement_only()
+    return expressions if expr.is_pure_statement() or expr.contains (n) -> n.is_pure_statement()
     Expressions.wrap([new CallNode(
       new ValueNode(literal(array), [new AccessorNode(literal('push'))]), [expr]
     )])
 
-}
             		           
                               
                            
                 #               
               
A faux-node used to wrap an expressions body in a closure.
             		                            
ClosureNode: exports.ClosureNode: {
+}
             		           
                               
                            
                 #               
               
A faux-node used to wrap an expressions body in a closure.
             		                            
ClosureNode: exports.ClosureNode: {
 
   wrap: (expressions, statement) ->
     func: new ParentheticalNode(new CodeNode([], Expressions.wrap([expressions])))
     call: new CallNode(new ValueNode(func, [new AccessorNode(literal('call'))]), [literal('this')])
     if statement then Expressions.wrap([call]) else call
 
-}
             		           
                               
                            
                 #               
               
Setting the value of a local variable, or the value of an object property.
             		                            
exports.AssignNode: class AssignNode extends BaseNode
+}
             		           
                               
                            
                 #               
               
Setting the value of a local variable, or the value of an object property.
             		                            
exports.AssignNode: class AssignNode extends BaseNode
   type: 'Assign'
 
   PROTO_ASSIGN: /^(\S+)\.prototype/
@@ -439,7 +438,7 @@ code generation to generate a quick "array.push(value)" tree of nodes.

     return "${@idt()}$val;" if stmt
     val: "($val)" if not top or o.returns
     val: "${@idt()}return $val" if o.returns
-    val
             		           
                               
                            
                 #               
               
Implementation of recursive pattern matching, when assigning array or
+    val             
           
                               
                            
                 #               
               
Implementation of recursive pattern matching, when assigning array or
 object literals to a value. Peeks at their properties to assign inner names.
 See: http://wiki.ecmascript.org/doku.php?id=harmony:destructuring
             		                            
  compile_pattern_match: (o) ->
     val_var: o.scope.free_variable()
@@ -469,7 +468,7 @@ See: http
     from:   range.from.compile(o)
     to:     range.to.compile(o) + ' - ' + from + plus
     val:    @value.compile(o)
-    "$name.splice.apply($name, [$from, $to].concat($val))"
             		           
                               
                            
                 #               
               
A function definition. The only node that creates a new Scope.
+    "$name.splice.apply($name, [$from, $to].concat($val))"             
           
                               
                            
                 #               
               
A function definition. The only node that creates a new Scope.
 A CodeNode does not have any children -- they're within the new scope.
             		                            
exports.CodeNode: class CodeNode extends BaseNode
   type: 'Code'
 
@@ -514,7 +513,7 @@ A CodeNode does not have any children -- they're within the new scope.

   toString: (idt) ->
     idt ||= ''
     children: (child.toString(idt + TAB) for child in @real_children()).join('')
-    "\n$idt$children"
             		           
                               
                            
                 #               
               
A splat, either as a parameter to a function, an argument to a call,
+    "\n$idt$children"             
           
                               
                            
                 #               
               
A splat, either as a parameter to a function, an argument to a call,
 or in a destructuring assignment.
             		                            
exports.SplatNode: class SplatNode extends BaseNode
   type: 'Splat'
 
@@ -531,7 +530,7 @@ or in a destructuring assignment.
             
             "$name = Array.prototype.slice.call(arguments, $@index)"
 
   compile_value: (o, name, index) ->
-    "Array.prototype.slice.call($name, $index)"                        
                               
                            
                 #               
               
A while loop, the only sort of low-level loop exposed by CoffeeScript. From
+    "Array.prototype.slice.call($name, $index)"             
           
                               
                            
                 #               
               
A while loop, the only sort of low-level loop exposed by CoffeeScript. From
 it, all other loops can be manufactured.
             		                            
exports.WhileNode: class WhileNode extends BaseNode
   type: 'While'
 
@@ -563,7 +562,7 @@ it, all other loops can be manufactured.
             
             @body:      Expressions.wrap([new IfNode(@filter, @body)]) if @filter
     "$pre {\n${ @body.compile(o) }\n${@idt()}}$post"
 
-statement WhileNode                        
                               
                            
                 #               
               
Simple Arithmetic and logical operations. Performs some conversion from
+statement WhileNode             
           
                               
                            
                 #               
               
Simple Arithmetic and logical operations. Performs some conversion from
 CoffeeScript operations into their JavaScript equivalents.
             		                            
exports.OpNode: class OpNode extends BaseNode
   type: 'Op'
 
@@ -599,7 +598,7 @@ CoffeeScript operations into their JavaScript equivalents.
             

          
             
                                      
                               
                            
                 #               
               
Mimic Python's chained comparisons. See:
+    [@first.compile(o), @operator, @second.compile(o)].join ' '             
           
                               
                            
                 #               
               
Mimic Python's chained comparisons. See:
 http://docs.python.org/reference/expressions.html#notin
             		                            
  compile_chain: (o) ->
     shared: @first.unwrap().second
     [@first.second, shared]: shared.compile_reference(o) if shared instanceof CallNode
@@ -621,7 +620,7 @@ CoffeeScript operations into their JavaScript equivalents.
             

            
       
                               
                               
                            
                 #               
               
A try/catch/finally block.
             		                            
exports.TryNode: class TryNode extends BaseNode
+    parts.join('')
             		           
                               
                            
                 #               
               
A try/catch/finally block.
             		                            
exports.TryNode: class TryNode extends BaseNode
   type: 'Try'
 
   constructor: (attempt, error, recovery, ensure) ->
@@ -638,7 +637,7 @@ CoffeeScript operations into their JavaScript equivalents.
             

              
                              
                               
                            
                 #               
               
Throw an exception.
             		                            
exports.ThrowNode: class ThrowNode extends BaseNode
+statement TryNode
             		           
                               
                            
                 #               
               
Throw an exception.
             		                            
exports.ThrowNode: class ThrowNode extends BaseNode
   type: 'Throw'
 
   constructor: (expression) ->
@@ -647,7 +646,7 @@ CoffeeScript operations into their JavaScript equivalents.
             

    
                               
                               
                            
                 #               
               
Check an expression for existence (meaning not null or undefined).
             		                            
exports.ExistenceNode: class ExistenceNode extends BaseNode
+statement ThrowNode, true
             		           
                               
                            
                 #               
               
Check an expression for existence (meaning not null or undefined).
             		                            
exports.ExistenceNode: class ExistenceNode extends BaseNode
   type: 'Existence'
 
   constructor: (expression) ->
@@ -661,7 +660,7 @@ CoffeeScript operations into their JavaScript equivalents.
             

            
       
                              
                               
                            
                 #               
               
An extra set of parentheses, specified explicitly in the source.
             		                            
exports.ParentheticalNode: class ParentheticalNode extends BaseNode
+  "(typeof $first !== \"undefined\" && $second !== null)"
             		           
                               
                            
                 #               
               
An extra set of parentheses, specified explicitly in the source.
             		                            
exports.ParentheticalNode: class ParentheticalNode extends BaseNode
   type: 'Paren'
 
   constructor: (expression) ->
@@ -675,7 +674,7 @@ CoffeeScript operations into their JavaScript equivalents.
             

        
        
                                   
                               
                            
                 #               
               
The replacement for the for loop is an array comprehension (that compiles)
+    "($code)"             
           
                               
                            
                 #               
               
The replacement for the for loop is an array comprehension (that compiles)
 into a for loop. Also acts as an expression, able to return the result
 of the comprehenion. Unlike Python array comprehensions, it's able to pass
 the current index of the loop as a second parameter.
             		                            
exports.ForNode: class ForNode extends BaseNode
@@ -742,7 +741,7 @@ the current index of the loop as a second parameter.
             

                   
                              
                               
                            
                 #               
               
If/else statements. Switch/whens get compiled into these. Acts as an
+statement ForNode             
           
                               
                            
                 #               
               
If/else statements. Switch/whens get compiled into these. Acts as an
 expression by pushing down requested returns to the expression bodies.
 Single-expression IfNodes are compiled into ternary operators if possible,
 because ternaries are first-class returnable assignable expressions.
             		                            
exports.IfNode: class IfNode extends BaseNode
@@ -764,9 +763,9 @@ because ternaries are first-class returnable assignable expressions.

 
   force_statement: ->
     @tags.statement: true
-    this
             		           
                               
                            
                 #               
               
Tag a chain of IfNodes with their switch condition for equality.
             		                            
  rewrite_condition: (expression) ->
+    this
             		           
                               
                            
                 #               
               
Tag a chain of IfNodes with their switch condition for equality.
             		                            
  rewrite_condition: (expression) ->
     @switcher: expression
-    this
             		           
                               
                            
                 #               
               
Rewrite a chain of IfNodes with their switch condition for equality.
             		                            
  rewrite_switch: (o) ->
+    this
             		           
                               
                            
                 #               
               
Rewrite a chain of IfNodes with their switch condition for equality.
             		                            
  rewrite_switch: (o) ->
     assigner: @switcher
     if not (@switcher.unwrap() instanceof LiteralNode)
       variable: literal(o.scope.free_variable())
@@ -778,14 +777,14 @@ because ternaries are first-class returnable assignable expressions.

     else
       new OpNode('is', assigner, @condition)
     @else_body.rewrite_condition(@switcher) if @is_chain()
-    this
             		           
                               
                            
                 #               
               
Rewrite a chain of IfNodes to add a default case as the final else.
             		                            
  add_else: (exprs, statement) ->
+    this
             		           
                               
                            
                 #               
               
Rewrite a chain of IfNodes to add a default case as the final else.
             		                            
  add_else: (exprs, statement) ->
     if @is_chain()
       @else_body.add_else exprs, statement
     else
       exprs: exprs.unwrap() unless statement
       @children.push @else_body: exprs
-    this
             		           
                               
                            
                 #               
               
If the else_body is an IfNode itself, then we've got an if-else chain.
             		                            
  is_chain: ->
-    @chain ||= @else_body and @else_body instanceof IfNode
             		           
                               
                            
                 #               
               
The IfNode only compiles into a statement if either of the bodies needs
+    this             
           
                               
                            
                 #               
               
If the else_body is an IfNode itself, then we've got an if-else chain.
             		                            
  is_chain: ->
+    @chain ||= @else_body and @else_body instanceof IfNode
             		           
                               
                            
                 #               
               
The IfNode only compiles into a statement if either of the bodies needs
 to be a statement.
             		                            
  is_statement: ->
     @statement ||= !!(@comment or @tags.statement or @body.is_statement() or (@else_body and @else_body.is_statement()))
 
@@ -793,7 +792,7 @@ to be a statement.
             
             
     (cond.compile(o) for cond in flatten([@condition])).join(' || ')
 
   compile_node: (o) ->
-    if @is_statement() then @compile_statement(o) else @compile_ternary(o)                        
                               
                            
                 #               
               
Compile the IfNode as a regular if-else statement. Flattened chains
+    if @is_statement() then @compile_statement(o) else @compile_ternary(o)             
           
                               
                            
                 #               
               
Compile the IfNode as a regular if-else statement. Flattened chains
 force sub-else bodies into statement form.
             		                            
  compile_statement: (o) ->
     @rewrite_switch(o) if @switcher
     child:        del o, 'chain_child'
@@ -811,9 +810,22 @@ force sub-else bodies into statement form.
             
             ' else ' + @else_body.compile(merge(o, {indent: @idt(), chain_child: true}))
     else
       " else {\n${ Expressions.wrap([@else_body]).compile(o) }\n${@idt()}}"
-    "$if_part$else_part"                        
                               
                            
                 #               
               
Compile the IfNode into a ternary operator.
             		                            
  compile_ternary: (o) ->
+    "$if_part$else_part"
             		           
                               
                            
                 #               
               
Compile the IfNode into a ternary operator.
             		                            
  compile_ternary: (o) ->
     if_part:    @condition.compile(o) + ' ? ' + @body.compile(o)
     else_part:  if @else_body then @else_body.compile(o) else 'null'
-    "$if_part : $else_part"
+    "$if_part : $else_part"
             		           
                               
                            
                 #               
               
Constants
             		                            
             		           
                               
                            
                 #               
               
Tabs are two spaces for pretty printing.
             		                            
TAB: '  '
+TRAILING_WHITESPACE: /\s+$/gm
             		           
                               
                            
                 #               
               
Keep the identifier regex in sync with the Lexer.
             		                            
IDENTIFIER:   /^[a-zA-Z$_](\w|\$)*$/
             		           
                               
                            
                 #               
               
Utility Functions
             		                            
             		           
                               
                            
                 #               
               
Merge objects.
             		                            
merge: (options, overrides) ->
+  fresh: {}
+  (fresh[key]: val) for key, val of options
+  (fresh[key]: val) for key, val of overrides if overrides
+  fresh
             		           
                               
                            
                 #               
               
Trim out all falsy values from an array.
             		                            
compact: (array) -> item for item in array when item
             		           
                               
                            
                 #               
               
Return a completely flattened version of an array.
             		                            
flatten: (array) ->
+  memo: []
+  for item in array
+    if item instanceof Array then memo: memo.concat(item) else memo.push(item)
+  memo
             		           
                               
                            
                 #               
               
Delete a key from an object, returning the value.
             		                            
del: (obj, key) ->
+  val: obj[key]
+  delete obj[key]
+  val
             		           
                               
                            
                 #               
               
Quickie helper for a generated LiteralNode.
             		                            
literal: (name) ->
+  new LiteralNode(name)
 
 
             		           
                     
   
   
\ No newline at end of file
diff --git a/lib/nodes.js b/lib/nodes.js
index 9e259c84..9a10e585 100644
--- a/lib/nodes.js
+++ b/lib/nodes.js
@@ -1,127 +1,83 @@
 (function(){
   var AccessorNode, ArrayNode, AssignNode, BaseNode, CallNode, ClassNode, ClosureNode, CodeNode, CommentNode, ExistenceNode, Expressions, ExtendsNode, ForNode, IDENTIFIER, IfNode, IndexNode, LiteralNode, ObjectNode, OpNode, ParentheticalNode, PushNode, RangeNode, ReturnNode, SliceNode, SplatNode, TAB, TRAILING_WHITESPACE, ThrowNode, TryNode, ValueNode, WhileNode, compact, del, flatten, literal, merge, statement;
-  var __hasProp = Object.prototype.hasOwnProperty, __extends = function(child, parent) {
+  var __extends = function(child, parent) {
     var ctor = function(){ };
     ctor.prototype = parent.prototype;
     child.__superClass__ = parent.prototype;
     child.prototype = new ctor();
     child.prototype.constructor = child;
-  };
+  }, __hasProp = Object.prototype.hasOwnProperty;
+  // `nodes.coffee` contains all of the node classes for the syntax tree. Most
+  // nodes are created as the result of actions in the [grammar](grammar.html),
+  // but some are created by other nodes as a method of code generation. To convert
+  // the syntax tree into a string of JavaScript code, call `compile()` on the root.
+  // Set up for both **Node.js** and the browser, by
+  // including the [Scope](scope.html) class.
   (typeof process !== "undefined" && process !== null) ? process.mixin(require('scope')) : (this.exports = this);
-  // Some helper functions
-  // Tabs are two spaces for pretty printing.
-  TAB = '  ';
-  TRAILING_WHITESPACE = /\s+$/gm;
-  // Keep the identifier regex in sync with the Lexer.
-  IDENTIFIER = /^[a-zA-Z$_](\w|\$)*$/;
-  // Merge objects.
-  merge = function merge(options, overrides) {
-    var _a, _b, fresh, key, val;
-    fresh = {};
-    _a = options;
-    for (key in _a) { if (__hasProp.call(_a, key)) {
-      val = _a[key];
-      ((fresh[key] = val));
-    }}
-    if (overrides) {
-      _b = overrides;
-      for (key in _b) { if (__hasProp.call(_b, key)) {
-        val = _b[key];
-        ((fresh[key] = val));
-      }}
-    }
-    return fresh;
-  };
-  // Trim out all falsy values from an array.
-  compact = function compact(array) {
-    var _a, _b, _c, _d, item;
-    _a = []; _b = array;
-    for (_c = 0, _d = _b.length; _c < _d; _c++) {
-      item = _b[_c];
-      if (item) {
-        _a.push(item);
-      }
-    }
-    return _a;
-  };
-  // Return a completely flattened version of an array.
-  flatten = function flatten(array) {
-    var _a, _b, _c, item, memo;
-    memo = [];
-    _a = array;
-    for (_b = 0, _c = _a.length; _b < _c; _b++) {
-      item = _a[_b];
-      item instanceof Array ? (memo = memo.concat(item)) : memo.push(item);
-    }
-    return memo;
-  };
-  // Delete a key from an object, returning the value.
-  del = function del(obj, key) {
-    var val;
-    val = obj[key];
-    delete obj[key];
-    return val;
-  };
-  // Quickie helper for a generated LiteralNode.
-  literal = function literal(name) {
-    return new LiteralNode(name);
-  };
-  // Mark a node as a statement, or a statement only.
+  // Helper function that marks a node as a JavaScript *statement*, or as a
+  // *pure_statement*. Statements must be wrapped in a closure when used as an
+  // expression, and nodes tagged as *pure_statement* cannot be closure-wrapped
+  // without losing their meaning.
   statement = function statement(klass, only) {
     klass.prototype.is_statement = function is_statement() {
       return true;
     };
     if (only) {
-      return ((klass.prototype.is_statement_only = function is_statement_only() {
+      return ((klass.prototype.is_pure_statement = function is_pure_statement() {
         return true;
       }));
     }
   };
-  // The abstract base class for all CoffeeScript nodes.
-  // All nodes are implement a "compile_node" method, which performs the
-  // code generation for that node. To compile a node, call the "compile"
-  // method, which wraps "compile_node" in some extra smarts, to know when the
-  // generated code should be wrapped up in a closure. An options hash is passed
-  // and cloned throughout, containing messages from higher in the AST,
-  // information about the current scope, and indentation level.
+  // The **BaseNode** is the abstract base class for all nodes in the syntax tree.
+  // Each subclass implements the `compile_node` method, which performs the
+  // code generation for that node. To compile a node to JavaScript,
+  // call `compile` on it, which wraps `compile_node` in some generic extra smarts,
+  // to know when the generated code needs to be wrapped up in a closure.
+  // An options hash is passed and cloned throughout, containing information about
+  // the environment from higher in the tree (such as if a returned value is
+  // being requested by the surrounding function), information about the current
+  // scope, and indentation level.
   exports.BaseNode = (function() {
     BaseNode = function BaseNode() {    };
-    // This is extremely important -- we convert JS statements into expressions
-    // by wrapping them in a closure, only if it's possible, and we're not at
+    // Common logic for determining whether to wrap this node in a closure before
+    // compiling it, or to compile directly. We need to wrap if this node is a
+    // *statement*, and it's not a *pure_statement*, and we're not at
     // the top level of a block (which would be unnecessary), and we haven't
-    // already been asked to return the result.
+    // already been asked to return the result (because statements know how to
+    // return results).
     BaseNode.prototype.compile = function compile(o) {
       var closure, top;
       this.options = merge(o || {});
-      this.indent = o.indent;
+      this.tab = o.indent;
       if (!(this.operation_sensitive())) {
         del(this.options, 'operation');
       }
       top = this.top_sensitive() ? this.options.top : del(this.options, 'top');
-      closure = this.is_statement() && !this.is_statement_only() && !top && !this.options.returns && !(this instanceof CommentNode) && !this.contains(function(node) {
-        return node.is_statement_only();
+      closure = this.is_statement() && !this.is_pure_statement() && !top && !this.options.returns && !(this instanceof CommentNode) && !this.contains(function(node) {
+        return node.is_pure_statement();
       });
       return closure ? this.compile_closure(this.options) : this.compile_node(this.options);
     };
-    // Statements converted into expressions share scope with their parent
-    // closure, to preserve JavaScript-style lexical scope.
+    // Statements converted into expressions via closure-wrapping share a scope
+    // object with their parent closure, to preserve the expected lexical scope.
     BaseNode.prototype.compile_closure = function compile_closure(o) {
-      this.indent = o.indent;
+      this.tab = o.indent;
       o.shared_scope = o.scope;
       return ClosureNode.wrap(this).compile(o);
     };
     // If the code generation wishes to use the result of a complex expression
-    // in multiple places, ensure that the expression is only ever evaluated once.
+    // in multiple places, ensure that the expression is only ever evaluated once,
+    // by assigning it to a temporary variable.
     BaseNode.prototype.compile_reference = function compile_reference(o) {
       var compiled, reference;
       reference = literal(o.scope.free_variable());
       compiled = new AssignNode(reference, this);
       return [compiled, reference];
     };
-    // Quick short method for the current indentation level, plus tabbing in.
+    // Convenience method to grab the current indentation level, plus tabbing in.
     BaseNode.prototype.idt = function idt(tabs) {
       var _a, _b, _c, _d, i, idt;
-      idt = (this.indent || '');
+      idt = this.tab || '';
       _c = 0; _d = (tabs || 0);
       for (_b = 0, i = _c; (_c <= _d ? i < _d : i > _d); (_c <= _d ? i += 1 : i -= 1), _b++) {
         idt += TAB;
@@ -179,7 +135,7 @@
     BaseNode.prototype.is_statement = function is_statement() {
       return false;
     };
-    BaseNode.prototype.is_statement_only = function is_statement_only() {
+    BaseNode.prototype.is_pure_statement = function is_pure_statement() {
       return false;
     };
     BaseNode.prototype.top_sensitive = function top_sensitive() {
@@ -241,8 +197,8 @@
     };
     // If this is the top-level Expressions, wrap everything in a safety closure.
     Expressions.prototype.compile_root = function compile_root(o) {
-      var code, indent;
-      o.indent = (this.indent = (indent = o.no_wrap ? '' : TAB));
+      var code;
+      o.indent = (this.tab = o.no_wrap ? '' : TAB);
       o.scope = new Scope(null, this, null);
       code = o.globals ? this.compile_node(o) : this.compile_with_declarations(o);
       code = code.replace(TRAILING_WHITESPACE, '');
@@ -257,23 +213,23 @@
         return node instanceof ValueNode && node.is_arguments();
       });
       if (args) {
-        code = (this.idt()) + "arguments = Array.prototype.slice.call(arguments, 0);\n" + code;
+        code = (this.tab) + "arguments = Array.prototype.slice.call(arguments, 0);\n" + code;
       }
       if (o.scope.has_assignments(this)) {
-        code = (this.idt()) + "var " + (o.scope.compiled_assignments()) + ";\n" + code;
+        code = (this.tab) + "var " + (o.scope.compiled_assignments()) + ";\n" + code;
       }
       if (o.scope.has_declarations(this)) {
-        code = (this.idt()) + "var " + (o.scope.compiled_declarations()) + ";\n" + code;
+        code = (this.tab) + "var " + (o.scope.compiled_declarations()) + ";\n" + code;
       }
       return code;
     };
     // Compiles a single expression within the expressions body.
     Expressions.prototype.compile_expression = function compile_expression(node, o) {
       var returns, stmt;
-      this.indent = o.indent;
+      this.tab = o.indent;
       stmt = node.is_statement();
       // We need to return the result if this is the last node in the expressions body.
-      returns = del(o, 'returns') && this.is_last(node) && !node.is_statement_only();
+      returns = del(o, 'returns') && this.is_last(node) && !node.is_pure_statement();
       // Return the regular compile of the node, unless we need to return the result.
       if (!(returns)) {
         return (stmt ? '' : this.idt()) + node.compile(merge(o, {
@@ -287,7 +243,7 @@
         }));
       }
       // Otherwise, we can just return the value of the expression.
-      return (this.idt()) + "return " + (node.compile(o)) + ";";
+      return (this.tab) + "return " + (node.compile(o)) + ";";
     };
     return Expressions;
   }).call(this);
@@ -313,7 +269,7 @@
     LiteralNode.prototype.is_statement = function is_statement() {
       return this.value === 'break' || this.value === 'continue';
     };
-    LiteralNode.prototype.is_statement_only = LiteralNode.prototype.is_statement;
+    LiteralNode.prototype.is_pure_statement = LiteralNode.prototype.is_statement;
     LiteralNode.prototype.compile_node = function compile_node(o) {
       var end, idt;
       idt = this.is_statement() ? this.idt() : '';
@@ -339,7 +295,7 @@
           returns: true
         }));
       }
-      return (this.idt()) + "return " + (this.expression.compile(o)) + ";";
+      return (this.tab) + "return " + (this.expression.compile(o)) + ";";
     };
     return ReturnNode;
   }).call(this);
@@ -428,7 +384,7 @@
     __extends(CommentNode, BaseNode);
     CommentNode.prototype.type = 'Comment';
     CommentNode.prototype.compile_node = function compile_node(o) {
-      return (this.idt()) + "//" + this.lines.join("\n" + (this.idt()) + "//");
+      return this.tab + "//" + this.lines.join("\n" + this.tab + "//");
     };
     return CommentNode;
   }).call(this);
@@ -569,14 +525,14 @@
     RangeNode.prototype.type = 'Range';
     RangeNode.prototype.compile_variables = function compile_variables(o) {
       var _a, _b, from, to;
-      this.indent = o.indent;
+      this.tab = o.indent;
       _a = [o.scope.free_variable(), o.scope.free_variable()];
       this.from_var = _a[0];
       this.to_var = _a[1];
       _b = [this.from.compile(o), this.to.compile(o)];
       from = _b[0];
       to = _b[1];
-      return this.from_var + " = " + from + "; " + this.to_var + " = " + to + ";\n" + (this.idt());
+      return this.from_var + " = " + from + "; " + this.to_var + " = " + to + ";\n" + this.tab;
     };
     RangeNode.prototype.compile_node = function compile_node(o) {
       var compare, equals, idx, incr, intro, step, vars;
@@ -753,7 +709,7 @@
         return _a;
       }).call(this);
       objects = objects.join('');
-      ending = objects.indexOf('\n') >= 0 ? "\n" + (this.idt()) + "]" : ']';
+      ending = objects.indexOf('\n') >= 0 ? "\n" + this.tab + "]" : ']';
       return "[" + objects + ending;
     };
     return ArrayNode;
@@ -764,8 +720,8 @@
     wrap: function wrap(array, expressions) {
       var expr;
       expr = expressions.unwrap();
-      if (expr.is_statement_only() || expr.contains(function(n) {
-        return n.is_statement_only();
+      if (expr.is_pure_statement() || expr.contains(function(n) {
+        return n.is_pure_statement();
       })) {
         return expressions;
       }
@@ -832,13 +788,13 @@
       }
       val = name + " = " + val;
       if (stmt) {
-        return (this.idt()) + val + ";";
+        return this.tab + val + ";";
       }
       if (!top || o.returns) {
         val = "(" + val + ")";
       }
       if (o.returns) {
-        val = (this.idt()) + "return " + val;
+        val = (this.tab) + "return " + val;
       }
       return val;
     };
@@ -849,7 +805,7 @@
       var _a, _b, _c, access_class, assigns, code, i, idx, obj, val, val_var, value;
       val_var = o.scope.free_variable();
       value = this.value.is_statement() ? ClosureNode.wrap(this.value) : this.value;
-      assigns = [(this.idt()) + val_var + " = " + (value.compile(o)) + ";"];
+      assigns = [this.tab + val_var + " = " + (value.compile(o)) + ";"];
       o.top = true;
       o.as_statement = true;
       _a = this.variable.base.objects;
@@ -874,7 +830,7 @@
       }
       code = assigns.join("\n");
       if (o.returns) {
-        code += "\n" + (this.idt()) + "return " + (this.variable.compile(o)) + ";";
+        code += "\n" + (this.tab) + "return " + (this.variable.compile(o)) + ";";
       }
       return code;
     };
@@ -942,7 +898,7 @@
         return func;
       }
       inner = "(function" + name_part + "() {\n" + (this.idt(2)) + "return __func.apply(__this, arguments);\n" + (this.idt(1)) + "});";
-      return "(function(__this) {\n" + (this.idt(1)) + "var __func = " + func + ";\n" + (this.idt(1)) + "return " + inner + "\n" + (this.idt()) + "})(this)";
+      return "(function(__this) {\n" + (this.idt(1)) + "var __func = " + func + ";\n" + (this.idt(1)) + "return " + inner + "\n" + this.tab + "})(this)";
     };
     CodeNode.prototype.top_sensitive = function top_sensitive() {
       return true;
@@ -1029,20 +985,20 @@
       set = '';
       if (!top) {
         rvar = o.scope.free_variable();
-        set = (this.idt()) + rvar + " = [];\n";
+        set = this.tab + rvar + " = [];\n";
         if (this.body) {
           this.body = PushNode.wrap(rvar, this.body);
         }
       }
-      post = returns ? "\n" + (this.idt()) + "return " + rvar + ";" : '';
-      pre = set + (this.idt()) + "while (" + cond + ")";
+      post = returns ? "\n" + (this.tab) + "return " + rvar + ";" : '';
+      pre = set + (this.tab) + "while (" + cond + ")";
       if (!this.body) {
         return pre + " null;" + post;
       }
       if (this.filter) {
         this.body = Expressions.wrap([new IfNode(this.filter, this.body)]);
       }
-      return pre + " {\n" + (this.body.compile(o)) + "\n" + (this.idt()) + "}" + post;
+      return pre + " {\n" + (this.body.compile(o)) + "\n" + this.tab + "}" + post;
     };
     return WhileNode;
   }).call(this);
@@ -1157,11 +1113,11 @@
       o.top = true;
       attempt_part = this.attempt.compile(o);
       error_part = this.error ? " (" + (this.error.compile(o)) + ") " : ' ';
-      catch_part = ((this.recovery || '') && ' catch') + error_part + "{\n" + (this.recovery.compile(o)) + "\n" + (this.idt()) + "}";
+      catch_part = ((this.recovery || '') && ' catch') + error_part + "{\n" + (this.recovery.compile(o)) + "\n" + this.tab + "}";
       finally_part = (this.ensure || '') && ' finally {\n' + this.ensure.compile(merge(o, {
         returns: null
-      })) + "\n" + (this.idt()) + "}";
-      return (this.idt()) + "try {\n" + attempt_part + "\n" + (this.idt()) + "}" + catch_part + finally_part;
+      })) + "\n" + this.tab + "}";
+      return (this.tab) + "try {\n" + attempt_part + "\n" + this.tab + "}" + catch_part + finally_part;
     };
     return TryNode;
   }).call(this);
@@ -1175,7 +1131,7 @@
     __extends(ThrowNode, BaseNode);
     ThrowNode.prototype.type = 'Throw';
     ThrowNode.prototype.compile_node = function compile_node(o) {
-      return (this.idt()) + "throw " + (this.expression.compile(o)) + ";";
+      return (this.tab) + "throw " + (this.expression.compile(o)) + ";";
     };
     return ThrowNode;
   }).call(this);
@@ -1288,7 +1244,7 @@
         for_part = index_var + " = 0, " + for_part + ", " + index_var + "++";
       } else {
         index_var = null;
-        source_part = svar + " = " + (this.source.compile(o)) + ";\n" + (this.idt());
+        source_part = svar + " = " + (this.source.compile(o)) + ";\n" + this.tab;
         if (name) {
           var_part = body_dent + name + " = " + svar + "[" + ivar + "];\n";
         }
@@ -1324,7 +1280,7 @@
         for_part = ivar + " in " + svar + ") { if (__hasProp.call(" + svar + ", " + ivar + ")";
       }
       if (!(top_level)) {
-        return_result = "\n" + (this.idt()) + return_result + ";";
+        return_result = "\n" + this.tab + return_result + ";";
       }
       body = body.compile(merge(o, {
         indent: body_dent,
@@ -1332,7 +1288,7 @@
       }));
       vars = range ? name : name + ", " + ivar;
       close = this.object ? '}}\n' : '}\n';
-      return set_result + (source_part) + "for (" + for_part + ") {\n" + var_part + body + "\n" + (this.idt()) + close + (this.idt()) + return_result;
+      return set_result + (source_part) + "for (" + for_part + ") {\n" + var_part + body + "\n" + this.tab + close + this.tab + return_result;
     };
     return ForNode;
   }).call(this);
@@ -1450,14 +1406,14 @@
       com_dent = child ? this.idt() : '';
       prefix = this.comment ? (this.comment.compile(cond_o)) + "\n" + com_dent : '';
       body = Expressions.wrap([this.body]).compile(o);
-      if_part = prefix + (if_dent) + "if (" + (this.compile_condition(cond_o)) + ") {\n" + body + "\n" + (this.idt()) + "}";
+      if_part = prefix + (if_dent) + "if (" + (this.compile_condition(cond_o)) + ") {\n" + body + "\n" + this.tab + "}";
       if (!(this.else_body)) {
         return if_part;
       }
       else_part = this.is_chain() ? ' else ' + this.else_body.compile(merge(o, {
         indent: this.idt(),
         chain_child: true
-      })) : " else {\n" + (Expressions.wrap([this.else_body]).compile(o)) + "\n" + (this.idt()) + "}";
+      })) : " else {\n" + (Expressions.wrap([this.else_body]).compile(o)) + "\n" + this.tab + "}";
       return if_part + else_part;
     };
     // Compile the IfNode into a ternary operator.
@@ -1469,4 +1425,65 @@
     };
     return IfNode;
   }).call(this);
+  // Constants
+  // ---------
+  // Tabs are two spaces for pretty printing.
+  TAB = '  ';
+  TRAILING_WHITESPACE = /\s+$/gm;
+  // Keep the identifier regex in sync with the Lexer.
+  IDENTIFIER = /^[a-zA-Z$_](\w|\$)*$/;
+  // Utility Functions
+  // -----------------
+  // Merge objects.
+  merge = function merge(options, overrides) {
+    var _a, _b, fresh, key, val;
+    fresh = {};
+    _a = options;
+    for (key in _a) { if (__hasProp.call(_a, key)) {
+      val = _a[key];
+      ((fresh[key] = val));
+    }}
+    if (overrides) {
+      _b = overrides;
+      for (key in _b) { if (__hasProp.call(_b, key)) {
+        val = _b[key];
+        ((fresh[key] = val));
+      }}
+    }
+    return fresh;
+  };
+  // Trim out all falsy values from an array.
+  compact = function compact(array) {
+    var _a, _b, _c, _d, item;
+    _a = []; _b = array;
+    for (_c = 0, _d = _b.length; _c < _d; _c++) {
+      item = _b[_c];
+      if (item) {
+        _a.push(item);
+      }
+    }
+    return _a;
+  };
+  // Return a completely flattened version of an array.
+  flatten = function flatten(array) {
+    var _a, _b, _c, item, memo;
+    memo = [];
+    _a = array;
+    for (_b = 0, _c = _a.length; _b < _c; _b++) {
+      item = _a[_b];
+      item instanceof Array ? (memo = memo.concat(item)) : memo.push(item);
+    }
+    return memo;
+  };
+  // Delete a key from an object, returning the value.
+  del = function del(obj, key) {
+    var val;
+    val = obj[key];
+    delete obj[key];
+    return val;
+  };
+  // Quickie helper for a generated LiteralNode.
+  literal = function literal(name) {
+    return new LiteralNode(name);
+  };
 })();
diff --git a/src/nodes.coffee b/src/nodes.coffee
index b6de32f5..e143e4d7 100644
--- a/src/nodes.coffee
+++ b/src/nodes.coffee
@@ -1,91 +1,68 @@
+# `nodes.coffee` contains all of the node classes for the syntax tree. Most
+# nodes are created as the result of actions in the [grammar](grammar.html),
+# but some are created by other nodes as a method of code generation. To convert
+# the syntax tree into a string of JavaScript code, call `compile()` on the root.
+
+# Set up for both **Node.js** and the browser, by
+# including the [Scope](scope.html) class.
 if process?
   process.mixin require 'scope'
 else
   this.exports: this
 
-# Some helper functions
-
-# Tabs are two spaces for pretty printing.
-TAB: '  '
-TRAILING_WHITESPACE: /\s+$/gm
-
-# Keep the identifier regex in sync with the Lexer.
-IDENTIFIER:   /^[a-zA-Z$_](\w|\$)*$/
-
-
-# Merge objects.
-merge: (options, overrides) ->
-  fresh: {}
-  (fresh[key]: val) for key, val of options
-  (fresh[key]: val) for key, val of overrides if overrides
-  fresh
-
-# Trim out all falsy values from an array.
-compact: (array) -> item for item in array when item
-
-# Return a completely flattened version of an array.
-flatten: (array) ->
-  memo: []
-  for item in array
-    if item instanceof Array then memo: memo.concat(item) else memo.push(item)
-  memo
-
-# Delete a key from an object, returning the value.
-del: (obj, key) ->
-  val: obj[key]
-  delete obj[key]
-  val
-
-# Quickie helper for a generated LiteralNode.
-literal: (name) ->
-  new LiteralNode(name)
-
-# Mark a node as a statement, or a statement only.
+# Helper function that marks a node as a JavaScript *statement*, or as a
+# *pure_statement*. Statements must be wrapped in a closure when used as an
+# expression, and nodes tagged as *pure_statement* cannot be closure-wrapped
+# without losing their meaning.
 statement: (klass, only) ->
   klass::is_statement: -> true
-  (klass::is_statement_only: -> true) if only
+  (klass::is_pure_statement: -> true) if only
 
-
-# The abstract base class for all CoffeeScript nodes.
-# All nodes are implement a "compile_node" method, which performs the
-# code generation for that node. To compile a node, call the "compile"
-# method, which wraps "compile_node" in some extra smarts, to know when the
-# generated code should be wrapped up in a closure. An options hash is passed
-# and cloned throughout, containing messages from higher in the AST,
-# information about the current scope, and indentation level.
+# The **BaseNode** is the abstract base class for all nodes in the syntax tree.
+# Each subclass implements the `compile_node` method, which performs the
+# code generation for that node. To compile a node to JavaScript,
+# call `compile` on it, which wraps `compile_node` in some generic extra smarts,
+# to know when the generated code needs to be wrapped up in a closure.
+# An options hash is passed and cloned throughout, containing information about
+# the environment from higher in the tree (such as if a returned value is
+# being requested by the surrounding function), information about the current
+# scope, and indentation level.
 exports.BaseNode: class BaseNode
 
-  # This is extremely important -- we convert JS statements into expressions
-  # by wrapping them in a closure, only if it's possible, and we're not at
+  # Common logic for determining whether to wrap this node in a closure before
+  # compiling it, or to compile directly. We need to wrap if this node is a
+  # *statement*, and it's not a *pure_statement*, and we're not at
   # the top level of a block (which would be unnecessary), and we haven't
-  # already been asked to return the result.
+  # already been asked to return the result (because statements know how to
+  # return results).
   compile: (o) ->
     @options: merge o or {}
-    @indent:  o.indent
+    @tab:     o.indent
     del @options, 'operation' unless @operation_sensitive()
     top:      if @top_sensitive() then @options.top else del @options, 'top'
-    closure:  @is_statement() and not @is_statement_only() and not top and
+    closure:  @is_statement() and not @is_pure_statement() and not top and
               not @options.returns and not (this instanceof CommentNode) and
-              not @contains (node) -> node.is_statement_only()
+              not @contains (node) -> node.is_pure_statement()
     if closure then @compile_closure(@options) else @compile_node(@options)
 
-  # Statements converted into expressions share scope with their parent
-  # closure, to preserve JavaScript-style lexical scope.
+  # Statements converted into expressions via closure-wrapping share a scope
+  # object with their parent closure, to preserve the expected lexical scope.
   compile_closure: (o) ->
-    @indent: o.indent
+    @tab: o.indent
     o.shared_scope: o.scope
-    ClosureNode.wrap(this).compile(o)
+    ClosureNode.wrap(this).compile o
 
   # If the code generation wishes to use the result of a complex expression
-  # in multiple places, ensure that the expression is only ever evaluated once.
+  # in multiple places, ensure that the expression is only ever evaluated once,
+  # by assigning it to a temporary variable.
   compile_reference: (o) ->
-    reference: literal(o.scope.free_variable())
-    compiled:  new AssignNode(reference, this)
+    reference: literal o.scope.free_variable()
+    compiled:  new AssignNode reference, this
     [compiled, reference]
 
-  # Quick short method for the current indentation level, plus tabbing in.
+  # Convenience method to grab the current indentation level, plus tabbing in.
   idt: (tabs) ->
-    idt: (@indent || '')
+    idt: @tab or ''
     idt += TAB for i in [0...(tabs or 0)]
     idt
 
@@ -111,7 +88,7 @@ exports.BaseNode: class BaseNode
   unwrap:               -> this
   children:             []
   is_statement:         -> false
-  is_statement_only:    -> false
+  is_pure_statement:    -> false
   top_sensitive:        -> false
   operation_sensitive:  -> false
 
@@ -157,7 +134,7 @@ exports.Expressions: class Expressions extends BaseNode
 
   # If this is the top-level Expressions, wrap everything in a safety closure.
   compile_root: (o) ->
-    o.indent: @indent: indent: if o.no_wrap then '' else TAB
+    o.indent: @tab: if o.no_wrap then '' else TAB
     o.scope: new Scope(null, this, null)
     code: if o.globals then @compile_node(o) else @compile_with_declarations(o)
     code: code.replace(TRAILING_WHITESPACE, '')
@@ -168,23 +145,23 @@ exports.Expressions: class Expressions extends BaseNode
   compile_with_declarations: (o) ->
     code: @compile_node(o)
     args: @contains (node) -> node instanceof ValueNode and node.is_arguments()
-    code: "${@idt()}arguments = Array.prototype.slice.call(arguments, 0);\n$code" if args
-    code: "${@idt()}var ${o.scope.compiled_assignments()};\n$code"  if o.scope.has_assignments(this)
-    code: "${@idt()}var ${o.scope.compiled_declarations()};\n$code" if o.scope.has_declarations(this)
+    code: "${@tab}arguments = Array.prototype.slice.call(arguments, 0);\n$code" if args
+    code: "${@tab}var ${o.scope.compiled_assignments()};\n$code"  if o.scope.has_assignments(this)
+    code: "${@tab}var ${o.scope.compiled_declarations()};\n$code" if o.scope.has_declarations(this)
     code
 
   # Compiles a single expression within the expressions body.
   compile_expression: (node, o) ->
-    @indent: o.indent
+    @tab: o.indent
     stmt:    node.is_statement()
     # We need to return the result if this is the last node in the expressions body.
-    returns: del(o, 'returns') and @is_last(node) and not node.is_statement_only()
+    returns: del(o, 'returns') and @is_last(node) and not node.is_pure_statement()
     # Return the regular compile of the node, unless we need to return the result.
     return (if stmt then '' else @idt()) + node.compile(merge(o, {top: true})) + (if stmt then '' else ';') unless returns
     # If it's a statement, the node knows how to return itself.
     return node.compile(merge(o, {returns: true})) if node.is_statement()
     # Otherwise, we can just return the value of the expression.
-    return "${@idt()}return ${node.compile(o)};"
+    return "${@tab}return ${node.compile(o)};"
 
 # Wrap up a node as an Expressions, unless it already is one.
 Expressions.wrap: (nodes) ->
@@ -207,7 +184,7 @@ exports.LiteralNode: class LiteralNode extends BaseNode
   is_statement: ->
     @value is 'break' or @value is 'continue'
 
-  is_statement_only: LiteralNode::is_statement
+  is_pure_statement: LiteralNode::is_statement
 
   compile_node: (o) ->
     idt: if @is_statement() then @idt() else ''
@@ -227,7 +204,7 @@ exports.ReturnNode: class ReturnNode extends BaseNode
 
   compile_node: (o) ->
     return @expression.compile(merge(o, {returns: true})) if @expression.is_statement()
-    "${@idt()}return ${@expression.compile(o)};"
+    "${@tab}return ${@expression.compile(o)};"
 
 statement ReturnNode, true
 
@@ -308,7 +285,7 @@ exports.CommentNode: class CommentNode extends BaseNode
     this
 
   compile_node: (o) ->
-    "${@idt()}//" + @lines.join("\n${@idt()}//")
+    "$@tab//" + @lines.join("\n$@tab//")
 
 statement CommentNode
 
@@ -426,10 +403,10 @@ exports.RangeNode: class RangeNode extends BaseNode
     @exclusive: !!exclusive
 
   compile_variables: (o) ->
-    @indent: o.indent
+    @tab: o.indent
     [@from_var, @to_var]: [o.scope.free_variable(), o.scope.free_variable()]
     [from, to]:           [@from.compile(o), @to.compile(o)]
-    "$@from_var = $from; $@to_var = $to;\n${@idt()}"
+    "$@from_var = $from; $@to_var = $to;\n$@tab"
 
   compile_node: (o) ->
     return    @compile_array(o) unless o.index
@@ -556,7 +533,7 @@ exports.ArrayNode: class ArrayNode extends BaseNode
       else
         "$code, "
     objects: objects.join('')
-    ending: if objects.indexOf('\n') >= 0 then "\n${@idt()}]" else ']'
+    ending: if objects.indexOf('\n') >= 0 then "\n$@tab]" else ']'
     "[$objects$ending"
 
 
@@ -566,7 +543,7 @@ PushNode: exports.PushNode: {
 
   wrap: (array, expressions) ->
     expr: expressions.unwrap()
-    return expressions if expr.is_statement_only() or expr.contains (n) -> n.is_statement_only()
+    return expressions if expr.is_pure_statement() or expr.contains (n) -> n.is_pure_statement()
     Expressions.wrap([new CallNode(
       new ValueNode(literal(array), [new AccessorNode(literal('push'))]), [expr]
     )])
@@ -621,9 +598,9 @@ exports.AssignNode: class AssignNode extends BaseNode
     return "$name: $val" if @context is 'object'
     o.scope.find name unless @is_value() and @variable.has_properties()
     val: "$name = $val"
-    return "${@idt()}$val;" if stmt
+    return "$@tab$val;" if stmt
     val: "($val)" if not top or o.returns
-    val: "${@idt()}return $val" if o.returns
+    val: "${@tab}return $val" if o.returns
     val
 
   # Implementation of recursive pattern matching, when assigning array or
@@ -632,7 +609,7 @@ exports.AssignNode: class AssignNode extends BaseNode
   compile_pattern_match: (o) ->
     val_var: o.scope.free_variable()
     value: if @value.is_statement() then ClosureNode.wrap(@value) else @value
-    assigns: ["${@idt()}$val_var = ${ value.compile(o) };"]
+    assigns: ["$@tab$val_var = ${ value.compile(o) };"]
     o.top: true
     o.as_statement: true
     for obj, i in @variable.base.objects
@@ -646,7 +623,7 @@ exports.AssignNode: class AssignNode extends BaseNode
         val: new ValueNode(literal(val_var), [new access_class(idx)])
       assigns.push(new AssignNode(obj, val).compile(o))
     code: assigns.join("\n")
-    code += "\n${@idt()}return ${ @variable.compile(o) };" if o.returns
+    code += "\n${@tab}return ${ @variable.compile(o) };" if o.returns
     code
 
   compile_splice: (o) ->
@@ -691,7 +668,7 @@ exports.CodeNode: class CodeNode extends BaseNode
     func: "($func)" if top and not @bound
     return func unless @bound
     inner: "(function$name_part() {\n${@idt(2)}return __func.apply(__this, arguments);\n${@idt(1)}});"
-    "(function(__this) {\n${@idt(1)}var __func = $func;\n${@idt(1)}return $inner\n${@idt()}})(this)"
+    "(function(__this) {\n${@idt(1)}var __func = $func;\n${@idt(1)}return $inner\n$@tab})(this)"
 
   top_sensitive: ->
     true
@@ -755,13 +732,13 @@ exports.WhileNode: class WhileNode extends BaseNode
     set:        ''
     if not top
       rvar:     o.scope.free_variable()
-      set:      "${@idt()}$rvar = [];\n"
+      set:      "$@tab$rvar = [];\n"
       @body:    PushNode.wrap(rvar, @body) if @body
-    post:       if returns then "\n${@idt()}return $rvar;" else ''
-    pre:        "$set${@idt()}while ($cond)"
+    post:       if returns then "\n${@tab}return $rvar;" else ''
+    pre:        "$set${@tab}while ($cond)"
     return      "$pre null;$post" if not @body
     @body:      Expressions.wrap([new IfNode(@filter, @body)]) if @filter
-    "$pre {\n${ @body.compile(o) }\n${@idt()}}$post"
+    "$pre {\n${ @body.compile(o) }\n$@tab}$post"
 
 statement WhileNode
 
@@ -845,9 +822,9 @@ exports.TryNode: class TryNode extends BaseNode
     o.top:        true
     attempt_part: @attempt.compile(o)
     error_part:   if @error then " (${ @error.compile(o) }) " else ' '
-    catch_part:   "${ (@recovery or '') and ' catch' }$error_part{\n${ @recovery.compile(o) }\n${@idt()}}"
-    finally_part: (@ensure or '') and ' finally {\n' + @ensure.compile(merge(o, {returns: null})) + "\n${@idt()}}"
-    "${@idt()}try {\n$attempt_part\n${@idt()}}$catch_part$finally_part"
+    catch_part:   "${ (@recovery or '') and ' catch' }$error_part{\n${ @recovery.compile(o) }\n$@tab}"
+    finally_part: (@ensure or '') and ' finally {\n' + @ensure.compile(merge(o, {returns: null})) + "\n$@tab}"
+    "${@tab}try {\n$attempt_part\n$@tab}$catch_part$finally_part"
 
 statement TryNode
 
@@ -860,7 +837,7 @@ exports.ThrowNode: class ThrowNode extends BaseNode
     @children: [@expression: expression]
 
   compile_node: (o) ->
-    "${@idt()}throw ${@expression.compile(o)};"
+    "${@tab}throw ${@expression.compile(o)};"
 
 statement ThrowNode, true
 
@@ -944,7 +921,7 @@ exports.ForNode: class ForNode extends BaseNode
       for_part:     "$index_var = 0, $for_part, $index_var++"
     else
       index_var:    null
-      source_part:  "$svar = ${ @source.compile(o) };\n${@idt()}"
+      source_part:  "$svar = ${ @source.compile(o) };\n$@tab"
       var_part:     "$body_dent$name = $svar[$ivar];\n" if name
       if not @object
         lvar:       scope.free_variable()
@@ -963,11 +940,11 @@ exports.ForNode: class ForNode extends BaseNode
     if @object
       o.scope.assign('__hasProp', 'Object.prototype.hasOwnProperty', true)
       for_part: "$ivar in $svar) { if (__hasProp.call($svar, $ivar)"
-    return_result:  "\n${@idt()}$return_result;" unless top_level
+    return_result:  "\n$@tab$return_result;" unless top_level
     body:           body.compile(merge(o, {indent: body_dent, top: true}))
     vars:           if range then name else "$name, $ivar"
     close:          if @object then '}}\n' else '}\n'
-    "$set_result${source_part}for ($for_part) {\n$var_part$body\n${@idt()}$close${@idt()}$return_result"
+    "$set_result${source_part}for ($for_part) {\n$var_part$body\n$@tab$close$@tab$return_result"
 
 statement ForNode
 
@@ -1054,12 +1031,12 @@ exports.IfNode: class IfNode extends BaseNode
     com_dent:     if child then @idt() else ''
     prefix:       if @comment then "${ @comment.compile(cond_o) }\n$com_dent" else ''
     body:         Expressions.wrap([@body]).compile(o)
-    if_part:      "$prefix${if_dent}if (${ @compile_condition(cond_o) }) {\n$body\n${@idt()}}"
+    if_part:      "$prefix${if_dent}if (${ @compile_condition(cond_o) }) {\n$body\n$@tab}"
     return if_part unless @else_body
     else_part: if @is_chain()
       ' else ' + @else_body.compile(merge(o, {indent: @idt(), chain_child: true}))
     else
-      " else {\n${ Expressions.wrap([@else_body]).compile(o) }\n${@idt()}}"
+      " else {\n${ Expressions.wrap([@else_body]).compile(o) }\n$@tab}"
     "$if_part$else_part"
 
   # Compile the IfNode into a ternary operator.
@@ -1067,3 +1044,43 @@ exports.IfNode: class IfNode extends BaseNode
     if_part:    @condition.compile(o) + ' ? ' + @body.compile(o)
     else_part:  if @else_body then @else_body.compile(o) else 'null'
     "$if_part : $else_part"
+
+# Constants
+# ---------
+
+# Tabs are two spaces for pretty printing.
+TAB: '  '
+TRAILING_WHITESPACE: /\s+$/gm
+
+# Keep the identifier regex in sync with the Lexer.
+IDENTIFIER:   /^[a-zA-Z$_](\w|\$)*$/
+
+# Utility Functions
+# -----------------
+
+# Merge objects.
+merge: (options, overrides) ->
+  fresh: {}
+  (fresh[key]: val) for key, val of options
+  (fresh[key]: val) for key, val of overrides if overrides
+  fresh
+
+# Trim out all falsy values from an array.
+compact: (array) -> item for item in array when item
+
+# Return a completely flattened version of an array.
+flatten: (array) ->
+  memo: []
+  for item in array
+    if item instanceof Array then memo: memo.concat(item) else memo.push(item)
+  memo
+
+# Delete a key from an object, returning the value.
+del: (obj, key) ->
+  val: obj[key]
+  delete obj[key]
+  val
+
+# Quickie helper for a generated LiteralNode.
+literal: (name) ->
+  new LiteralNode(name)
diff --git a/test/test_expressions.coffee b/test/test_expressions.coffee
index 891aa5f2..a25f95c7 100644
--- a/test/test_expressions.coffee
+++ b/test/test_expressions.coffee
@@ -1,4 +1,4 @@
-# Ensure that we don't wrap Nodes that are "statement_only" in a closure.
+# Ensure that we don't wrap Nodes that are "pure_statement" in a closure.
 
 items: [1, 2, 3, "bacon", 4, 5]