Class: FastRuby::ScopeModeHelper

Inherits:
Object
  • Object
show all
Defined in:
lib/fastruby/translator/scope_mode_helper.rb

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.get_scope_mode(tree_) ⇒ Object 



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# File 'lib/fastruby/translator/scope_mode_helper.rb', line 25

def self.get_scope_mode(tree_)
  new.get_scope_mode(tree_)
end

Instance Method Details

#get_scope_mode(tree_) ⇒ Object 



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# File 'lib/fastruby/translator/scope_mode_helper.rb', line 29

def get_scope_mode(tree_)
  tree = FastRuby::FastRubySexp.from_sexp(tree_)

  if tree.node_type == :defn
    args_tree = tree[2]
    impl_tree = tree[3]
  elsif tree.node_type == :defs
    args_tree = tree[3]
    impl_tree = tree[4]
  end

  graph = impl_tree.to_graph

  args_tree[1..-1].each do |subtree|
    return :dag if subtree.to_s =~ /^\&/
  end

  tree.walk_tree do |subtree|
    if subtree.node_type == :iter
      iter_impl = subtree[3]
      
      return :dag if has_local_variable_access?(subtree[3])
      return :dag if subtree[2]

      if iter_impl
        return_node = iter_impl.find_tree{|st2| st2.node_type == :return}

        if return_node
          return :dag
        end
      end
    elsif subtree.node_type == :block_pass
      return :dag
    end
  end

  impl_tree.walk_tree do |subtree|
    graph.each_path_from(subtree) do |path|
      # verify path prohibitive for :linear scope (local variable read after call)
      has_call = false
      writes = Set.new

      path.each do |st2|
        next unless st2 
        if st2.node_type == :call
          if has_call and st2[1] == nil
            return :dag
          end

          writes.clear
          has_call = true
        elsif st2.node_type == :iter
          if has_call and st2[1][1] == nil
            return :dag
          end

          writes.clear
          has_call = true
        elsif st2.node_type == :lasgn
          writes << st2[1] # record local writes
        elsif st2.node_type == :lvar or st2.node_type == :self or 
              st2.node_type == :return or st2.node_type == :yield

          if has_call
            if st2.node_type == :lvar
              if writes.include? st2[1]
                # no problem
              else
                # read after call, the scope of this function must be implemented on heap
                return :dag
              end
            else
              return :dag
            end              
          end
        end
      end
    end
  end

  :linear
end