"""scons.Node.Alias

Alias nodes.

This creates a hash of global Aliases (dummy targets).

"""

#
# Copyright (c) 2001, 2002, 2003, 2004 The SCons Foundation
#
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# a copy of this software and associated documentation files (the
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# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
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# The above copyright notice and this permission notice shall be included
# in all copies or substantial portions of the Software.
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# KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
# WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
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__revision__ = "/home/scons/scons/branch.0/baseline/src/engine/SCons/Node/Alias.py 0.96.1.D001 2004/08/23 09:55:29 knight"

import UserDict

import SCons.Errors
import SCons.Node
import SCons.Util

class AliasNameSpace(UserDict.UserDict):
    def Alias(self, name):
        if self.has_key(name):
            raise SCons.Errors.UserError
        self[name] = SCons.Node.Alias.Alias(name)
        return self[name]

    def lookup(self, name):
        try:
            return self[name]
        except KeyError:
            return None

class Alias(SCons.Node.Node):
    def __init__(self, name):
        SCons.Node.Node.__init__(self)
        self.name = name

    def __str__(self):
        return self.name

    def build(self):
        """A "builder" for aliases."""
        pass

    current = SCons.Node.Node.children_are_up_to_date

    def sconsign(self):
        """An Alias is not recorded in .sconsign files"""
        pass

    def is_under(self, dir):
        # Make Alias nodes get built regardless of 
        # what directory scons was run from. Alias nodes
        # are outside the filesystem:
        return 1

    def get_contents(self):
        """The contents of an alias is the concatenation
        of all the contents of its sources"""
        contents = ""
        for kid in self.children(None):
            contents = contents + kid.get_contents()
        return contents
        
default_ans = AliasNameSpace()

SCons.Node.arg2nodes_lookups.append(default_ans.lookup)