"""SCons.Taskmaster

Generic Taskmaster.

"""

#
# Copyright (c) 2001 Steven Knight
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# 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:
#
# The above copyright notice and this permission notice shall be included
# in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
# 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
# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
#

__revision__ = "__FILE__ __REVISION__ __DATE__ __DEVELOPER__"




import SCons.Node



class Task:
    """Default SCons build engine task."""
    def __init__(self,target):
        self.target = target

    def execute(self):
        self.target.build()

    def set_state(self, state):
        return self.target.set_state(state)
        
def current(node):
    """Default SCons build engine is-it-current function.

    This returns "always out of date," so every node is always
    built/visited.
    """
    return None



class Taskmaster:
    """A generic Taskmaster for handling a bunch of targets.

    Classes that override methods of this class should call
    the base class method, so this class can do it's thing.    
    """

    def __init__(self, targets=[], tasker=Task, current=current):
        self.walkers = map(SCons.Node.Walker, targets)
        self.tasker = tasker
        self.current = current
        self.targets = targets

    def next_task(self):
        while self.walkers:
            n = self.walkers[0].next()
            if n == None:
                self.walkers.pop(0)
            elif n.get_state() == SCons.Node.up_to_date:
                self.up_to_date(n, self.walkers[0].is_done())
            elif n.get_state() == SCons.Node.failed:
                # XXX do the right thing here
                pass
            elif n.get_state() == SCons.Node.executing:
                # XXX do the right thing here
                pass
            elif n.get_state() == SCons.Node.executed:
                # skip this node because it has already been executed
                pass
            elif self.current(n):
                n.set_state(SCons.Node.up_to_date)
                self.up_to_date(n, self.walkers[0].is_done())
            else:
                n.set_state(SCons.Node.executing)
                return self.tasker(n)
	return None
 
    def is_blocked(self):
        return 0

    def up_to_date(self, node):
        pass

    def executed(self, task):
        task.set_state(SCons.Node.executed)

    def failed(self, task):
        self.walkers = []
        task.set_state(SCons.Node.failed)