text: # Copyright 2003, 2004, 2006 Vladimir Prus 
  # Distributed under the Boost Software License, Version 1.0. 
  # (See accompanying file LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt) 
  
  # Status: ported (danielw)
  # Base revision: 56043
  
  #  This module defines the 'alias' rule and associated class.
  #
  #  Alias is just a main target which returns its source targets without any 
  #  processing. For example::
  #
  #    alias bin : hello test_hello ;
  #    alias lib : helpers xml_parser ;
  #
  #  Another important use of 'alias' is to conveniently group source files::
  #
  #    alias platform-src : win.cpp : <os>NT ;
  #    alias platform-src : linux.cpp : <os>LINUX ;
  #    exe main : main.cpp platform-src ;
  # 
  #  Lastly, it's possible to create local alias for some target, with different
  #  properties::
  #
  #    alias big_lib : : @/external_project/big_lib/<link>static ;
  #
  
  import targets
  import property_set
  from b2.manager import get_manager
  
  from b2.util import metatarget
  
  class AliasTarget(targets.BasicTarget):
  
      def __init__(self, *args):
          targets.BasicTarget.__init__(self, *args)
  
      def construct(self, name, source_targets, properties):
          return [property_set.empty(), source_targets]
  
      def compute_usage_requirements(self, subvariant):
          base = targets.BasicTarget.compute_usage_requirements(self, subvariant)
          # Add source's usage requirement. If we don't do this, "alias" does not
          # look like 100% alias.
          return base.add(subvariant.sources_usage_requirements())
  
  @metatarget
  def alias(name, sources=[], requirements=[], default_build=[], usage_requirements=[]):
  
      project = get_manager().projects().current()
      targets = get_manager().targets()
  
      targets.main_target_alternative(AliasTarget(
          name, project,
          targets.main_target_sources(sources, name, no_renaming=True),
          targets.main_target_requirements(requirements or [], project),
          targets.main_target_default_build(default_build, project),
          targets.main_target_usage_requirements(usage_requirements or [], project)))
  
  # Declares the 'alias' target. It will build sources, and return them unaltered.
  get_manager().projects().add_rule("alias", alias)
  
  