   @options: dup(o || {})
   @indent:  o.indent
   top:      if @top_sensitive() then o.top else del obj 'top'
-  closure:  @statement() and not @statement_only() and not top and
+  closure:  @is_statement() and not @is_statement_only() and not top and
             not o.returns and not this instanceof CommentNode and
-            not @contains (node) -> node.statement_only()
+            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

    (output[key]: val) for key, val of input
    output

# Delete a key from an object, returning the value.
del: (obj, key) ->
  val: obj[key]
  delete obj[key]
  val

# # Provide a quick implementation of a children method.
# children: (klass, attrs...) ->
#   klass::children: ->

  false

# Default implementations of the common node methods.
Node::unwrap:             -> this
Node::children:           []
Node::is_statement:       -> false
Node::is_statement_only:  -> false
Node::top_sensitive:      -> false


# A collection of nodes, each one representing an expression.
Expressions: exports.Expressions: inherit Node, {

  constructor: (nodes...) ->
    @expressions: flatten nodes
    @children: @expressions

  # Wrap up a node as an Expressions, unless it already is.
  wrap: (nodes...) ->
    return nodes[0] if nodes.length is 1 and nodes[0] instanceof Expressions
    new Expressions(nodes...)

  # 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) ->
    @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) ->
    l: @expressions.length
    @last_index ||= if @expressions[l - 1] instanceof CommentNode then -2 else -1
    node is @expressions[l - @last_index]

  compile: (o) ->
    if o.scope then super(o) else @compile_root(o)

  # Compile each expression in the Expressions body.
  compile_node: (o) ->
    (@compile_expression(node, dup(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})();"

  # 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.arguments()
    argv: if args and o.scope.check('arguments') then '' else 'var '
    code: @idt() + argv + "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) ->
    @indent: o.indent
    stmt:    node.is_statement()
    # We need to return the result if this is the last node in the expressions body.
    returns: o.returns and @is_last(node) and not node.is_statement_only()
    delete o.returns
    # 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()
    # If it's not part of a constructor, we can just return the value of the expression.
    return @idt() + 'return ' + node.compile(o) unless o.scope.function?.is_constructor()
    # It's the last line of a constructor, add a safety check.
    temp: o.scope.free_variable()
    @idt() + temp + ' = ' + node.compile(o) + ";\n" + @idt() + "return " + o.scope.function.name + ' === this.constructor ? this : ' + temp + ';'
}

statement Expressions


# Literals are static values that can be passed through directly into
# JavaScript without translation, eg.: strings, numbers, true, false, null...
LiteralNode: exports.LiteralNode: (value) ->
  @value: value
  @children: [value]

# Break and continue must be treated as statements -- they lose their meaning
# when wrapped in a closure.
LiteralNode::is_statement: ->
  @value is 'break' or @value is 'continue'

LiteralNode::is_statement_only: LiteralNode::is_statement

LiteralNode::compile_node: (o) ->














































