work on nodes.coffee and adding scope.coffee

src/nodes.coffee

@@ -1,3 +1,31 @@
+# Some helper functions
+
+# TODO -- shallow (1 deep) flatten..
+# need recursive version..
+flatten: (aggList, newList) ->
+  for item in newList
+    aggList.push(item)
+  aggList
+
+compact: (input) ->
+  compected: []
+  for item in input
+    if item?
+      compacted.push(item)
+
+dup: (input) ->
+  output: null
+  if input instaceof Array
+    output: []
+    for val in input
+      output.push(val)
+  else
+    output: {}
+    for key, val of input
+      output.key: val
+    output
+  output
+
 # 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"
@@ -25,22 +53,11 @@ exports.Node::mark_as_statement_only: ->
 exports.Node::mark_as_top_sensitive: ->
   this.is_top_sensitive: -> true
 
-flatten: (aggList, newList) ->
-  for item in newList
-    aggList.push(item)
-  aggList
-
-compact: (input) ->
-  compected: []
-  for item in input
-    if item?
-      compacted.push(item)
-
 # Provide a quick implementation of a children method.
 exports.Node::children: (attributes) ->
   # TODO -- are these optimal impls of flatten and compact
   # .. do better ones exist in a stdlib?
-  agg = []
+  agg: []
   for item in attributes
     agg: flatten agg, item
   compacted: compact agg
@@ -51,6 +68,7 @@ exports.Node::write: (code) ->
   # hm.. 
   # TODO -- should print to STDOUT in "VERBOSE" how to
   # go about this.. ? jsonify 'this'?
+  # use node's puts ??
   code
 
 # This is extremely important -- we convert JS statements into expressions
@@ -85,14 +103,11 @@ exports.Node::idt: (tLvl) ->
     tabAmt: tabAmt + this.TAB
   this.indent + tabAmt
 
-exports.Node::is_a_node: ->
-  true
-
 #Does this node, or any of it's children, contain a node of a certain kind?
 exports.Node::do_i_contain: (block) ->
   for node in this.children
     return true if block(node)
-    return true if node.is_a_node() and node.do_i_contain(block)
+    return true if node instanceof exports.Node and node.do_i_contain(block)
   false
 
 # Default implementations of the common node methods.
@@ -102,7 +117,102 @@ exports.Node::is_a_statement: -> false
 exports.Node::is_a_statement_only: -> false
 exports.Node::is_top_sensitive: -> false
 
-exports.Expressions : exports.Node
+# A collection of nodes, each one representing an expression.
+exports.Expressions: (nodes) ->
+  this.mark_as_statement()
+  this.expressions: []
+  this.children([this.expressions])
+  for n in nodes
+    this.expressions: flatten this.expressions, n
+exports.Expressions extends exports.Node
+
+exports.Expressions::TRAILING_WHITESPACE: /\s+$/
+
+# Wrap up a node as an Expressions, unless it already is.
+exports.Expressions::wrap: (nodes) ->
+  return nodes[0] if nodes.length == 1 and nodes[0] instanceof exports.Expressions
+  new Expressions(nodes)
+
+# Tack an expression on to the end of this expression list.
+exports.Expressions::push: (node) ->
+  this.expressions.push(node)
+  this
+
+# Tack an expression on to the beginning of this expression list.
+exports.Expressions::unshift: (node) ->
+  this.expressions.unshift(node)
+  this
+
+# If this Expressions consists of a single node, pull it back out.
+exports.Expressions::unwrap: ->
+  if this.expressions.length == 1 then this.expressions[0] else this
+
+# Is this an empty block of code?
+exports.Expressions::is_empty: ->
+  this.expressions.length == 0
+
+# Is the node last in this block of expressions.
+exports.Expressions::is_last: (node) ->
+  arr_length: this.expressions.length
+  this.last_index ||= if this.expressions[arr_length - 1] instanceof exports.CommentNode then -2 else -1
+  node == this.expressions[arr_length - this.last_index]
+
+exports.Expressions::compile: (o) ->
+  opts: if o? then o else {}
+  if opts.scope then super(dup(opts)) else this.compile_root(o)
+
+# Compile each expression in the Expressions body.
+exports.Expressions::compile_node: (options) ->
+  opts: if options? then options else {}
+  compiled: []
+  for e in this.expressions
+    compiled.push(this.compile_expression(e, dup(options)))
+  code: ''
+  for line in compiled
+    code: code + line + '\n'
+
+# If this is the top-level Expressions, wrap everything in a safety closure.
+exports.Expressions::compile_root: (o) ->
+  opts: if o? then o else {}
+  indent: if opts.no_wrap then '' else this.TAB
+  this.indent: indent
+  opts.indent: indent
+  opts.scope: new Scope(null, this, null)
+  code: if opts.globals then compile_node(opts) else compile_with_declarations(opts)
+  code.replace(this.TRAILING_WHITESPACE, '')
+  this.write(if opts.no_wrap then code else "(function(){\n"+code+"\n})();")
+
+# Compile the expressions body, with declarations of all inner variables
+# at the top.
+exports.Expressions::compile_with_declaractions: (o) ->
+  opts: if o? : o else {}
+  code: this.compile_node(opts)
+  args: this.do_i_contain (n) -> n instanceof LiteralNode and n.arguments?
+  argv: if args and opts.scope.arguments then '' else 'var '
+  code: this.idt() + argv+"arguments = Array.prototype.slice.call(arguments, 0);\n"+code if args
+  code: this.idt() + "var "+opts.scope.compiled_assignments+";\n"+code if o.scope.has_assignments(this)
+  this.write(code)
+
+    # Compiles a single expression within the expression list.
+    def compile_expression(node, o)
+      @indent = o[:indent]
+      stmt    = node.statement?
+      # We need to return the result if this is the last node in the expressions body.
+      returns = o.delete(:return) && last?(node) && !node.statement_only?
+      # Return the regular compile of the node, unless we need to return the result.
+      return "#{stmt ? '' : idt}#{node.compile(o.merge(:top => true))}#{stmt ? '' : ';'}" unless returns
+      # If it's a statement, the node knows how to return itself.
+      return node.compile(o.merge(:return => true)) if node.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 && o[:scope].function.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};"
+    end
+
+  end
+
+
 exports.LiteralNode : exports.Node
 exports.ReturnNode : exports.Node
 exports.CommentNode : exports.Node

src/scope.coffee

@@ -0,0 +1,99 @@
+dup: (input) ->
+  output: null
+  if input instaceof Array
+    output: []
+    for val in input
+      output.push(val)
+  else
+    output: {}
+    for key, val of input
+      output.key: val
+    output
+  output
+
+# scope objects form a tree corresponding to the shape of the function 
+# definitions present in the script. They provide lexical scope, to determine 
+# whether a variable has been seen before or if it needs to be declared.
+exports.Scope: (parent, expressions, func) ->
+  # Initialize a scope with its parent, for lookups up the chain,
+  # as well as the Expressions body where it should declare its variables,
+  # and the function that it wraps.
+  this.parent: parent
+  this.expressions: expressions
+  this.function: func
+  this.variables: {}
+  this.temp_variable: if this.parent then dup(this.parent.temp_variable) : '__a'
+
+# Look up a variable in lexical scope, or declare it if not found.
+exports.Scope::find: (name, rem) ->
+  remote: if rem? then rem else false
+  found: this.check(name)
+  return found if found || remote
+  this.variables[name]: 'var'
+  found
+
+# Define a local variable as originating from a parameter in current scope
+# -- no var required.
+exports.Scope::parameter: (name) ->
+  this.variables[name]: = 'param'
+
+# Just check to see if a variable has already been declared.
+exports.Scope::check: (name) ->
+  return true if this.variables[name]?
+  # TODO: what does that ruby !! mean..? need to follow up
+  # .. this next line is prolly wrong ..
+  not not (this.parent and this.parent.check(name))
+
+# You can reset a found variable on the immediate scope.
+exports.Scope::reset: (name) ->
+  this.variables[name]: undefined
+
+exports.Scope::free_variable: ->
+  # need .succ! impl
+
+    # Find an available, short, name for a compiler-generated variable.
+    def free_variable
+      @temp_variable.succ! while check(@temp_variable)
+      @variables[@temp_variable.to_sym] = :var
+      Value.new(@temp_variable.dup)
+    end
+
+    # Ensure that an assignment is made at the top of scope (or top-level
+    # scope, if requested).
+    def assign(name, value, top=false)
+      return @parent.assign(name, value, top) if top && @parent
+      @variables[name.to_sym] = Value.new(value)
+    end
+
+    def declarations?(body)
+      !declared_variables.empty? && body == @expressions
+    end
+
+    def assignments?(body)
+      !assigned_variables.empty? && body == @expressions
+    end
+
+    # Return the list of variables first declared in current scope.
+    def declared_variables
+      @variables.select {|k, v| v == :var }.map {|pair| pair[0].to_s }.sort
+    end
+
+    # Return the list of variables that are supposed to be assigned at the top
+    # of scope.
+    def assigned_variables
+      @variables.select {|k, v| v.is_a?(Value) }.sort_by {|pair| pair[0].to_s }
+    end
+
+    def compiled_declarations
+      declared_variables.join(', ')
+    end
+
+    def compiled_assignments
+      assigned_variables.map {|name, val| "#{name} = #{val}"}.join(', ')
+    end
+
+    def inspect
+      "<Scope:#{__id__} #{@variables.inspect}>"
+    end
+
+  end