Class: Subaltern::Function

Inherits:
Object
  • Object
show all
Defined in:
lib/subaltern/evaluator.rb

Overview

Wrapper for function trees when stored in Context instances.

Direct Known Subclasses

LoopFunction

Instance Method Summary collapse

Constructor Details

#initialize(tree) ⇒ Function

Returns a new instance of Function.



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# File 'lib/subaltern/evaluator.rb', line 185

def initialize(tree)

  @tree = tree

  # TODO : eventually, follow Block's example and split the tree here
end

Instance Method Details

#call(context, tree) ⇒ Object 



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# File 'lib/subaltern/evaluator.rb', line 192

def call(context, tree)

  meth_args = @tree[2][1..-1]
  l = meth_args.last
  meth_arg_defaults = l.is_a?(Array) && l.first == :block ? l[1..-1] : []
  call_args = tree[3][1..-1].collect { |t| Subaltern.eval_tree(context, t) }

  con = Context.new(context, {})

  # bind arguments

  call_args.each_with_index do |arg, i|
    name = meth_args[i].to_s
    if m = name.match(/^\*(.+)$/)
      con[m[1]] = call_args[i..-1]
      break
    end
    con[name] = arg
  end

  # bind default arguments (when necessary)

  meth_arg_defaults.each do |d|
    name = d[1].to_s
    con[name] = Subaltern.eval_tree(context, d[2]) unless con.has_key?(name)
  end

  # is there a block ?

  if m = (meth_args.last || '').to_s.match(/^&(.+)/)
    con[m[1]] = context['__block']
  end

  # now do it

  begin
    Subaltern.eval_tree(con, @tree[3])
  rescue Return => r
    r.value
  end
end