1 files changed, 0 insertions, 1049 deletions
diff --git a/3rdParty/SCons/scons-2.4.0/engine/SCons/Taskmaster.py b/3rdParty/SCons/scons-2.4.0/engine/SCons/Taskmaster.py
deleted file mode 100644
index b303f79..0000000
--- a/3rdParty/SCons/scons-2.4.0/engine/SCons/Taskmaster.py
+++ /dev/null
@@ -1,1049 +0,0 @@
-#
-# Copyright (c) 2001 - 2015 The SCons Foundation
-#
-# 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.
-
-__doc__ = """
-Generic Taskmaster module for the SCons build engine.
-
-This module contains the primary interface(s) between a wrapping user
-interface and the SCons build engine.  There are two key classes here:
-
-    Taskmaster
-        This is the main engine for walking the dependency graph and
-        calling things to decide what does or doesn't need to be built.
-
-    Task
-        This is the base class for allowing a wrapping interface to
-        decide what does or doesn't actually need to be done.  The
-        intention is for a wrapping interface to subclass this as
-        appropriate for different types of behavior it may need.
-
-        The canonical example is the SCons native Python interface,
-        which has Task subclasses that handle its specific behavior,
-        like printing "`foo' is up to date" when a top-level target
-        doesn't need to be built, and handling the -c option by removing
-        targets as its "build" action.  There is also a separate subclass
-        for suppressing this output when the -q option is used.
-
-        The Taskmaster instantiates a Task object for each (set of)
-        target(s) that it decides need to be evaluated and/or built.
-"""
-
-__revision__ = "src/engine/SCons/Taskmaster.py rel_2.4.0:3365:9259ea1c13d7 2015/09/21 14:03:43 bdbaddog"
-
-from itertools import chain
-import operator
-import sys
-import traceback
-
-import SCons.Errors
-import SCons.Node
-import SCons.Warnings
-
-StateString = SCons.Node.StateString
-NODE_NO_STATE = SCons.Node.no_state
-NODE_PENDING = SCons.Node.pending
-NODE_EXECUTING = SCons.Node.executing
-NODE_UP_TO_DATE = SCons.Node.up_to_date
-NODE_EXECUTED = SCons.Node.executed
-NODE_FAILED = SCons.Node.failed
-
-print_prepare = 0               # set by option --debug=prepare
-
-# A subsystem for recording stats about how different Nodes are handled by
-# the main Taskmaster loop.  There's no external control here (no need for
-# a --debug= option); enable it by changing the value of CollectStats.
-
-CollectStats = None
-
-class Stats(object):
-    """
-    A simple class for holding statistics about the disposition of a
-    Node by the Taskmaster.  If we're collecting statistics, each Node
-    processed by the Taskmaster gets one of these attached, in which case
-    the Taskmaster records its decision each time it processes the Node.
-    (Ideally, that's just once per Node.)
-    """
-    def __init__(self):
-        """
-        Instantiates a Taskmaster.Stats object, initializing all
-        appropriate counters to zero.
-        """
-        self.considered  = 0
-        self.already_handled  = 0
-        self.problem  = 0
-        self.child_failed  = 0
-        self.not_built  = 0
-        self.side_effects  = 0
-        self.build  = 0
-
-StatsNodes = []
-
-fmt = "%(considered)3d "\
-      "%(already_handled)3d " \
-      "%(problem)3d " \
-      "%(child_failed)3d " \
-      "%(not_built)3d " \
-      "%(side_effects)3d " \
-      "%(build)3d "
-
-def dump_stats():
-    for n in sorted(StatsNodes, key=lambda a: str(a)):
-        print (fmt % n.stats.__dict__) + str(n)
-
-
-
-class Task(object):
-    """
-    Default SCons build engine task.
-
-    This controls the interaction of the actual building of node
-    and the rest of the engine.
-
-    This is expected to handle all of the normally-customizable
-    aspects of controlling a build, so any given application
-    *should* be able to do what it wants by sub-classing this
-    class and overriding methods as appropriate.  If an application
-    needs to customze something by sub-classing Taskmaster (or
-    some other build engine class), we should first try to migrate
-    that functionality into this class.
-
-    Note that it's generally a good idea for sub-classes to call
-    these methods explicitly to update state, etc., rather than
-    roll their own interaction with Taskmaster from scratch.
-    """
-    def __init__(self, tm, targets, top, node):
-        self.tm = tm
-        self.targets = targets
-        self.top = top
-        self.node = node
-        self.exc_clear()
-
-    def trace_message(self, method, node, description='node'):
-        fmt = '%-20s %s %s\n'
-        return fmt % (method + ':', description, self.tm.trace_node(node))
-
-    def display(self, message):
-        """
-        Hook to allow the calling interface to display a message.
-
-        This hook gets called as part of preparing a task for execution
-        (that is, a Node to be built).  As part of figuring out what Node
-        should be built next, the actually target list may be altered,
-        along with a message describing the alteration.  The calling
-        interface can subclass Task and provide a concrete implementation
-        of this method to see those messages.
-        """
-        pass
-
-    def prepare(self):
-        """
-        Called just before the task is executed.
-
-        This is mainly intended to give the target Nodes a chance to
-        unlink underlying files and make all necessary directories before
-        the Action is actually called to build the targets.
-        """
-        global print_prepare
-        T = self.tm.trace
-        if T: T.write(self.trace_message(u'Task.prepare()', self.node))
-
-        # Now that it's the appropriate time, give the TaskMaster a
-        # chance to raise any exceptions it encountered while preparing
-        # this task.
-        self.exception_raise()
-
-        if self.tm.message:
-            self.display(self.tm.message)
-            self.tm.message = None
-
-        # Let the targets take care of any necessary preparations.
-        # This includes verifying that all of the necessary sources
-        # and dependencies exist, removing the target file(s), etc.
-        #
-        # As of April 2008, the get_executor().prepare() method makes
-        # sure that all of the aggregate sources necessary to build this
-        # Task's target(s) exist in one up-front check.  The individual
-        # target t.prepare() methods check that each target's explicit
-        # or implicit dependencies exists, and also initialize the
-        # .sconsign info.
-        executor = self.targets[0].get_executor()
-        if executor is None:
-            return
-        executor.prepare()
-        for t in executor.get_action_targets():
-            if print_prepare:
-                print "Preparing target %s..."%t
-                for s in t.side_effects:
-                    print "...with side-effect %s..."%s
-            t.prepare()
-            for s in t.side_effects:
-                if print_prepare:
-                    print "...Preparing side-effect %s..."%s
-                s.prepare()
-
-    def get_target(self):
-        """Fetch the target being built or updated by this task.
-        """
-        return self.node
-
-    def needs_execute(self):
-        # TODO(deprecate):  "return True" is the old default behavior;
-        # change it to NotImplementedError (after running through the
-        # Deprecation Cycle) so the desired behavior is explicitly
-        # determined by which concrete subclass is used.
-        #raise NotImplementedError
-        msg = ('Taskmaster.Task is an abstract base class; instead of\n'
-              '\tusing it directly, '
-              'derive from it and override the abstract methods.')
-        SCons.Warnings.warn(SCons.Warnings.TaskmasterNeedsExecuteWarning, msg)
-        return True
-
-    def execute(self):
-        """
-        Called to execute the task.
-
-        This method is called from multiple threads in a parallel build,
-        so only do thread safe stuff here.  Do thread unsafe stuff in
-        prepare(), executed() or failed().
-        """
-        T = self.tm.trace
-        if T: T.write(self.trace_message(u'Task.execute()', self.node))
-
-        try:
-            cached_targets = []
-            for t in self.targets:
-                if not t.retrieve_from_cache():
-                    break
-                cached_targets.append(t)
-            if len(cached_targets) < len(self.targets):
-                # Remove targets before building. It's possible that we
-                # partially retrieved targets from the cache, leaving
-                # them in read-only mode. That might cause the command
-                # to fail.
-                #
-                for t in cached_targets:
-                    try:
-                        t.fs.unlink(t.get_internal_path())
-                    except (IOError, OSError):
-                        pass
-                self.targets[0].build()
-            else:
-                for t in cached_targets:
-                    t.cached = 1
-        except SystemExit:
-            exc_value = sys.exc_info()[1]
-            raise SCons.Errors.ExplicitExit(self.targets[0], exc_value.code)
-        except SCons.Errors.UserError:
-            raise
-        except SCons.Errors.BuildError:
-            raise
-        except Exception, e:
-            buildError = SCons.Errors.convert_to_BuildError(e)
-            buildError.node = self.targets[0]
-            buildError.exc_info = sys.exc_info()
-            raise buildError
-
-    def executed_without_callbacks(self):
-        """
-        Called when the task has been successfully executed
-        and the Taskmaster instance doesn't want to call
-        the Node's callback methods.
-        """
-        T = self.tm.trace
-        if T: T.write(self.trace_message('Task.executed_without_callbacks()',
-                                         self.node))
-
-        for t in self.targets:
-            if t.get_state() == NODE_EXECUTING:
-                for side_effect in t.side_effects:
-                    side_effect.set_state(NODE_NO_STATE)
-                t.set_state(NODE_EXECUTED)
-
-    def executed_with_callbacks(self):
-        """
-        Called when the task has been successfully executed and
-        the Taskmaster instance wants to call the Node's callback
-        methods.
-
-        This may have been a do-nothing operation (to preserve build
-        order), so we must check the node's state before deciding whether
-        it was "built", in which case we call the appropriate Node method.
-        In any event, we always call "visited()", which will handle any
-        post-visit actions that must take place regardless of whether
-        or not the target was an actual built target or a source Node.
-        """
-        global print_prepare
-        T = self.tm.trace
-        if T: T.write(self.trace_message('Task.executed_with_callbacks()',
-                                         self.node))
-
-        for t in self.targets:
-            if t.get_state() == NODE_EXECUTING:
-                for side_effect in t.side_effects:
-                    side_effect.set_state(NODE_NO_STATE)
-                t.set_state(NODE_EXECUTED)
-                if not t.cached:
-                    t.push_to_cache()
-                t.built()
-                t.visited()
-                if (not print_prepare and 
-                    (not hasattr(self, 'options') or not self.options.debug_includes)):
-                    t.release_target_info()
-            else:
-                t.visited()
-
-    executed = executed_with_callbacks
-
-    def failed(self):
-        """
-        Default action when a task fails:  stop the build.
-
-        Note: Although this function is normally invoked on nodes in
-        the executing state, it might also be invoked on up-to-date
-        nodes when using Configure().
-        """
-        self.fail_stop()
-
-    def fail_stop(self):
-        """
-        Explicit stop-the-build failure.
-
-        This sets failure status on the target nodes and all of
-        their dependent parent nodes.
-
-        Note: Although this function is normally invoked on nodes in
-        the executing state, it might also be invoked on up-to-date
-        nodes when using Configure().
-        """
-        T = self.tm.trace
-        if T: T.write(self.trace_message('Task.failed_stop()', self.node))
-
-        # Invoke will_not_build() to clean-up the pending children
-        # list.
-        self.tm.will_not_build(self.targets, lambda n: n.set_state(NODE_FAILED))
-
-        # Tell the taskmaster to not start any new tasks
-        self.tm.stop()
-
-        # We're stopping because of a build failure, but give the
-        # calling Task class a chance to postprocess() the top-level
-        # target under which the build failure occurred.
-        self.targets = [self.tm.current_top]
-        self.top = 1
-
-    def fail_continue(self):
-        """
-        Explicit continue-the-build failure.
-
-        This sets failure status on the target nodes and all of
-        their dependent parent nodes.
-
-        Note: Although this function is normally invoked on nodes in
-        the executing state, it might also be invoked on up-to-date
-        nodes when using Configure().
-        """
-        T = self.tm.trace
-        if T: T.write(self.trace_message('Task.failed_continue()', self.node))
-
-        self.tm.will_not_build(self.targets, lambda n: n.set_state(NODE_FAILED))
-
-    def make_ready_all(self):
-        """
-        Marks all targets in a task ready for execution.
-
-        This is used when the interface needs every target Node to be
-        visited--the canonical example being the "scons -c" option.
-        """
-        T = self.tm.trace
-        if T: T.write(self.trace_message('Task.make_ready_all()', self.node))
-
-        self.out_of_date = self.targets[:]
-        for t in self.targets:
-            t.disambiguate().set_state(NODE_EXECUTING)
-            for s in t.side_effects:
-                # add disambiguate here to mirror the call on targets above
-                s.disambiguate().set_state(NODE_EXECUTING)
-
-    def make_ready_current(self):
-        """
-        Marks all targets in a task ready for execution if any target
-        is not current.
-
-        This is the default behavior for building only what's necessary.
-        """
-        global print_prepare
-        T = self.tm.trace
-        if T: T.write(self.trace_message(u'Task.make_ready_current()',
-                                         self.node))
-
-        self.out_of_date = []
-        needs_executing = False
-        for t in self.targets:
-            try:
-                t.disambiguate().make_ready()
-                is_up_to_date = not t.has_builder() or \
-                                (not t.always_build and t.is_up_to_date())
-            except EnvironmentError, e:
-                raise SCons.Errors.BuildError(node=t, errstr=e.strerror, filename=e.filename)
-
-            if not is_up_to_date:
-                self.out_of_date.append(t)
-                needs_executing = True
-
-        if needs_executing:
-            for t in self.targets:
-                t.set_state(NODE_EXECUTING)
-                for s in t.side_effects:
-                    # add disambiguate here to mirror the call on targets in first loop above
-                    s.disambiguate().set_state(NODE_EXECUTING)
-        else:
-            for t in self.targets:
-                # We must invoke visited() to ensure that the node
-                # information has been computed before allowing the
-                # parent nodes to execute. (That could occur in a
-                # parallel build...)
-                t.visited()
-                t.set_state(NODE_UP_TO_DATE)
-                if (not print_prepare and 
-                    (not hasattr(self, 'options') or not self.options.debug_includes)):
-                    t.release_target_info()
-
-    make_ready = make_ready_current
-
-    def postprocess(self):
-        """
-        Post-processes a task after it's been executed.
-
-        This examines all the targets just built (or not, we don't care
-        if the build was successful, or even if there was no build
-        because everything was up-to-date) to see if they have any
-        waiting parent Nodes, or Nodes waiting on a common side effect,
-        that can be put back on the candidates list.
-        """
-        T = self.tm.trace
-        if T: T.write(self.trace_message(u'Task.postprocess()', self.node))
-
-        # We may have built multiple targets, some of which may have
-        # common parents waiting for this build.  Count up how many
-        # targets each parent was waiting for so we can subtract the
-        # values later, and so we *don't* put waiting side-effect Nodes
-        # back on the candidates list if the Node is also a waiting
-        # parent.
-
-        targets = set(self.targets)
-
-        pending_children = self.tm.pending_children
-        parents = {}
-        for t in targets:
-            # A node can only be in the pending_children set if it has
-            # some waiting_parents.
-            if t.waiting_parents:
-                if T: T.write(self.trace_message(u'Task.postprocess()',
-                                                 t,
-                                                 'removing'))
-                pending_children.discard(t)
-            for p in t.waiting_parents:
-                parents[p] = parents.get(p, 0) + 1
-
-        for t in targets:
-            if t.side_effects is not None:
-                for s in t.side_effects:
-                    if s.get_state() == NODE_EXECUTING:
-                        s.set_state(NODE_NO_STATE)
-                        for p in s.waiting_parents:
-                            parents[p] = parents.get(p, 0) + 1
-                    for p in s.waiting_s_e:
-                        if p.ref_count == 0:
-                            self.tm.candidates.append(p)
-
-        for p, subtract in parents.items():
-            p.ref_count = p.ref_count - subtract
-            if T: T.write(self.trace_message(u'Task.postprocess()',
-                                             p,
-                                             'adjusted parent ref count'))
-            if p.ref_count == 0:
-                self.tm.candidates.append(p)
-
-        for t in targets:
-            t.postprocess()
-
-    # Exception handling subsystem.
-    #
-    # Exceptions that occur while walking the DAG or examining Nodes
-    # must be raised, but must be raised at an appropriate time and in
-    # a controlled manner so we can, if necessary, recover gracefully,
-    # possibly write out signature information for Nodes we've updated,
-    # etc.  This is done by having the Taskmaster tell us about the
-    # exception, and letting
-
-    def exc_info(self):
-        """
-        Returns info about a recorded exception.
-        """
-        return self.exception
-
-    def exc_clear(self):
-        """
-        Clears any recorded exception.
-
-        This also changes the "exception_raise" attribute to point
-        to the appropriate do-nothing method.
-        """
-        self.exception = (None, None, None)
-        self.exception_raise = self._no_exception_to_raise
-
-    def exception_set(self, exception=None):
-        """
-        Records an exception to be raised at the appropriate time.
-
-        This also changes the "exception_raise" attribute to point
-        to the method that will, in fact
-        """
-        if not exception:
-            exception = sys.exc_info()
-        self.exception = exception
-        self.exception_raise = self._exception_raise
-
-    def _no_exception_to_raise(self):
-        pass
-
-    def _exception_raise(self):
-        """
-        Raises a pending exception that was recorded while getting a
-        Task ready for execution.
-        """
-        exc = self.exc_info()[:]
-        try:
-            exc_type, exc_value, exc_traceback = exc
-        except ValueError:
-            exc_type, exc_value = exc
-            exc_traceback = None
-        raise exc_type, exc_value, exc_traceback
-
-class AlwaysTask(Task):
-    def needs_execute(self):
-        """
-        Always returns True (indicating this Task should always
-        be executed).
-
-        Subclasses that need this behavior (as opposed to the default
-        of only executing Nodes that are out of date w.r.t. their
-        dependencies) can use this as follows:
-
-            class MyTaskSubclass(SCons.Taskmaster.Task):
-                needs_execute = SCons.Taskmaster.Task.execute_always
-        """
-        return True
-
-class OutOfDateTask(Task):
-    def needs_execute(self):
-        """
-        Returns True (indicating this Task should be executed) if this
-        Task's target state indicates it needs executing, which has
-        already been determined by an earlier up-to-date check.
-        """
-        return self.targets[0].get_state() == SCons.Node.executing
-
-
-def find_cycle(stack, visited):
-    if stack[-1] in visited:
-        return None
-    visited.add(stack[-1])
-    for n in stack[-1].waiting_parents:
-        stack.append(n)
-        if stack[0] == stack[-1]:
-            return stack
-        if find_cycle(stack, visited):
-            return stack
-        stack.pop()
-    return None
-
-
-class Taskmaster(object):
-    """
-    The Taskmaster for walking the dependency DAG.
-    """
-
-    def __init__(self, targets=[], tasker=None, order=None, trace=None):
-        self.original_top = targets
-        self.top_targets_left = targets[:]
-        self.top_targets_left.reverse()
-        self.candidates = []
-        if tasker is None:
-            tasker = OutOfDateTask
-        self.tasker = tasker
-        if not order:
-            order = lambda l: l
-        self.order = order
-        self.message = None
-        self.trace = trace
-        self.next_candidate = self.find_next_candidate
-        self.pending_children = set()
-
-    def find_next_candidate(self):
-        """
-        Returns the next candidate Node for (potential) evaluation.
-
-        The candidate list (really a stack) initially consists of all of
-        the top-level (command line) targets provided when the Taskmaster
-        was initialized.  While we walk the DAG, visiting Nodes, all the
-        children that haven't finished processing get pushed on to the
-        candidate list.  Each child can then be popped and examined in
-        turn for whether *their* children are all up-to-date, in which
-        case a Task will be created for their actual evaluation and
-        potential building.
-
-        Here is where we also allow candidate Nodes to alter the list of
-        Nodes that should be examined.  This is used, for example, when
-        invoking SCons in a source directory.  A source directory Node can
-        return its corresponding build directory Node, essentially saying,
-        "Hey, you really need to build this thing over here instead."
-        """
-        try:
-            return self.candidates.pop()
-        except IndexError:
-            pass
-        try:
-            node = self.top_targets_left.pop()
-        except IndexError:
-            return None
-        self.current_top = node
-        alt, message = node.alter_targets()
-        if alt:
-            self.message = message
-            self.candidates.append(node)
-            self.candidates.extend(self.order(alt))
-            node = self.candidates.pop()
-        return node
-
-    def no_next_candidate(self):
-        """
-        Stops Taskmaster processing by not returning a next candidate.
-
-        Note that we have to clean-up the Taskmaster candidate list
-        because the cycle detection depends on the fact all nodes have
-        been processed somehow.
-        """
-        while self.candidates:
-            candidates = self.candidates
-            self.candidates = []
-            self.will_not_build(candidates)
-        return None
-
-    def _validate_pending_children(self):
-        """
-        Validate the content of the pending_children set. Assert if an
-        internal error is found.
-
-        This function is used strictly for debugging the taskmaster by
-        checking that no invariants are violated. It is not used in
-        normal operation.
-
-        The pending_children set is used to detect cycles in the
-        dependency graph. We call a "pending child" a child that is
-        found in the "pending" state when checking the dependencies of
-        its parent node.
-
-        A pending child can occur when the Taskmaster completes a loop
-        through a cycle. For example, lets imagine a graph made of
-        three node (A, B and C) making a cycle. The evaluation starts
-        at node A. The taskmaster first consider whether node A's
-        child B is up-to-date. Then, recursively, node B needs to
-        check whether node C is up-to-date. This leaves us with a
-        dependency graph looking like:
-
-                                      Next candidate \
-                                                      \
-        Node A (Pending) --> Node B(Pending) --> Node C (NoState)
-                ^                                     |
-                |                                     |
-                +-------------------------------------+
-
-        Now, when the Taskmaster examines the Node C's child Node A,
-        it finds that Node A is in the "pending" state. Therefore,
-        Node A is a pending child of node C.
-
-        Pending children indicate that the Taskmaster has potentially
-        loop back through a cycle. We say potentially because it could
-        also occur when a DAG is evaluated in parallel. For example,
-        consider the following graph:
-
-
-        Node A (Pending) --> Node B(Pending) --> Node C (Pending) --> ...
-                |                                     ^
-                |                                     |
-                +----------> Node D (NoState) --------+
-                                  /
-                  Next candidate /
-
-        The Taskmaster first evaluates the nodes A, B, and C and
-        starts building some children of node C. Assuming, that the
-        maximum parallel level has not been reached, the Taskmaster
-        will examine Node D. It will find that Node C is a pending
-        child of Node D.
-
-        In summary, evaluating a graph with a cycle will always
-        involve a pending child at one point. A pending child might
-        indicate either a cycle or a diamond-shaped DAG. Only a
-        fraction of the nodes ends-up being a "pending child" of
-        another node. This keeps the pending_children set small in
-        practice.
-
-        We can differentiate between the two cases if we wait until
-        the end of the build. At this point, all the pending children
-        nodes due to a diamond-shaped DAG will have been properly
-        built (or will have failed to build). But, the pending
-        children involved in a cycle will still be in the pending
-        state.
-
-        The taskmaster removes nodes from the pending_children set as
-        soon as a pending_children node moves out of the pending
-        state. This also helps to keep the pending_children set small.
-        """
-
-        for n in self.pending_children:
-            assert n.state in (NODE_PENDING, NODE_EXECUTING), \
-                (str(n), StateString[n.state])
-            assert len(n.waiting_parents) != 0, (str(n), len(n.waiting_parents))
-            for p in n.waiting_parents:
-                assert p.ref_count > 0, (str(n), str(p), p.ref_count)
-
-
-    def trace_message(self, message):
-        return 'Taskmaster: %s\n' % message
-
-    def trace_node(self, node):
-        return '<%-10s %-3s %s>' % (StateString[node.get_state()],
-                                    node.ref_count,
-                                    repr(str(node)))
-
-    def _find_next_ready_node(self):
-        """
-        Finds the next node that is ready to be built.
-
-        This is *the* main guts of the DAG walk.  We loop through the
-        list of candidates, looking for something that has no un-built
-        children (i.e., that is a leaf Node or has dependencies that are
-        all leaf Nodes or up-to-date).  Candidate Nodes are re-scanned
-        (both the target Node itself and its sources, which are always
-        scanned in the context of a given target) to discover implicit
-        dependencies.  A Node that must wait for some children to be
-        built will be put back on the candidates list after the children
-        have finished building.  A Node that has been put back on the
-        candidates list in this way may have itself (or its sources)
-        re-scanned, in order to handle generated header files (e.g.) and
-        the implicit dependencies therein.
-
-        Note that this method does not do any signature calculation or
-        up-to-date check itself.  All of that is handled by the Task
-        class.  This is purely concerned with the dependency graph walk.
-        """
-
-        self.ready_exc = None
-
-        T = self.trace
-        if T: T.write(u'\n' + self.trace_message('Looking for a node to evaluate'))
-
-        while True:
-            node = self.next_candidate()
-            if node is None:
-                if T: T.write(self.trace_message('No candidate anymore.') + u'\n')
-                return None
-
-            node = node.disambiguate()
-            state = node.get_state()
-
-            # For debugging only:
-            #
-            # try:
-            #     self._validate_pending_children()
-            # except:
-            #     self.ready_exc = sys.exc_info()
-            #     return node
-
-            if CollectStats:
-                if not hasattr(node, 'stats'):
-                    node.stats = Stats()
-                    StatsNodes.append(node)
-                S = node.stats
-                S.considered = S.considered + 1
-            else:
-                S = None
-
-            if T: T.write(self.trace_message(u'    Considering node %s and its children:' % self.trace_node(node)))
-
-            if state == NODE_NO_STATE:
-                # Mark this node as being on the execution stack:
-                node.set_state(NODE_PENDING)
-            elif state > NODE_PENDING:
-                # Skip this node if it has already been evaluated:
-                if S: S.already_handled = S.already_handled + 1
-                if T: T.write(self.trace_message(u'       already handled (executed)'))
-                continue
-
-            executor = node.get_executor()
-
-            try:
-                children = executor.get_all_children()
-            except SystemExit:
-                exc_value = sys.exc_info()[1]
-                e = SCons.Errors.ExplicitExit(node, exc_value.code)
-                self.ready_exc = (SCons.Errors.ExplicitExit, e)
-                if T: T.write(self.trace_message('       SystemExit'))
-                return node
-            except Exception, e:
-                # We had a problem just trying to figure out the
-                # children (like a child couldn't be linked in to a
-                # VariantDir, or a Scanner threw something).  Arrange to
-                # raise the exception when the Task is "executed."
-                self.ready_exc = sys.exc_info()
-                if S: S.problem = S.problem + 1
-                if T: T.write(self.trace_message('       exception %s while scanning children.\n' % e))
-                return node
-
-            children_not_visited = []
-            children_pending = set()
-            children_not_ready = []
-            children_failed = False
-
-            for child in chain(executor.get_all_prerequisites(), children):
-                childstate = child.get_state()
-
-                if T: T.write(self.trace_message(u'       ' + self.trace_node(child)))
-
-                if childstate == NODE_NO_STATE:
-                    children_not_visited.append(child)
-                elif childstate == NODE_PENDING:
-                    children_pending.add(child)
-                elif childstate == NODE_FAILED:
-                    children_failed = True
-
-                if childstate <= NODE_EXECUTING:
-                    children_not_ready.append(child)
-
-
-            # These nodes have not even been visited yet.  Add
-            # them to the list so that on some next pass we can
-            # take a stab at evaluating them (or their children).
-            children_not_visited.reverse()
-            self.candidates.extend(self.order(children_not_visited))
-            #if T and children_not_visited:
-            #    T.write(self.trace_message('     adding to candidates: %s' % map(str, children_not_visited)))
-            #    T.write(self.trace_message('     candidates now: %s\n' % map(str, self.candidates)))
-
-            # Skip this node if any of its children have failed.
-            #
-            # This catches the case where we're descending a top-level
-            # target and one of our children failed while trying to be
-            # built by a *previous* descent of an earlier top-level
-            # target.
-            #
-            # It can also occur if a node is reused in multiple
-            # targets. One first descends though the one of the
-            # target, the next time occurs through the other target.
-            #
-            # Note that we can only have failed_children if the
-            # --keep-going flag was used, because without it the build
-            # will stop before diving in the other branch.
-            #
-            # Note that even if one of the children fails, we still
-            # added the other children to the list of candidate nodes
-            # to keep on building (--keep-going).
-            if children_failed:
-                for n in executor.get_action_targets():
-                    n.set_state(NODE_FAILED)
-
-                if S: S.child_failed = S.child_failed + 1
-                if T: T.write(self.trace_message('****** %s\n' % self.trace_node(node)))
-                continue
-
-            if children_not_ready:
-                for child in children_not_ready:
-                    # We're waiting on one or more derived targets
-                    # that have not yet finished building.
-                    if S: S.not_built = S.not_built + 1
-
-                    # Add this node to the waiting parents lists of
-                    # anything we're waiting on, with a reference
-                    # count so we can be put back on the list for
-                    # re-evaluation when they've all finished.
-                    node.ref_count =  node.ref_count + child.add_to_waiting_parents(node)
-                    if T: T.write(self.trace_message(u'     adjusted ref count: %s, child %s' %
-                                  (self.trace_node(node), repr(str(child)))))
-
-                if T:
-                    for pc in children_pending:
-                        T.write(self.trace_message('       adding %s to the pending children set\n' %
-                                self.trace_node(pc)))
-                self.pending_children = self.pending_children | children_pending
-
-                continue
-
-            # Skip this node if it has side-effects that are
-            # currently being built:
-            wait_side_effects = False
-            for se in executor.get_action_side_effects():
-                if se.get_state() == NODE_EXECUTING:
-                    se.add_to_waiting_s_e(node)
-                    wait_side_effects = True
-
-            if wait_side_effects:
-                if S: S.side_effects = S.side_effects + 1
-                continue
-
-            # The default when we've gotten through all of the checks above:
-            # this node is ready to be built.
-            if S: S.build = S.build + 1
-            if T: T.write(self.trace_message(u'Evaluating %s\n' %
-                                             self.trace_node(node)))
-
-            # For debugging only:
-            #
-            # try:
-            #     self._validate_pending_children()
-            # except:
-            #     self.ready_exc = sys.exc_info()
-            #     return node
-
-            return node
-
-        return None
-
-    def next_task(self):
-        """
-        Returns the next task to be executed.
-
-        This simply asks for the next Node to be evaluated, and then wraps
-        it in the specific Task subclass with which we were initialized.
-        """
-        node = self._find_next_ready_node()
-
-        if node is None:
-            return None
-
-        executor = node.get_executor()
-        if executor is None:
-            return None
-        
-        tlist = executor.get_all_targets()
-
-        task = self.tasker(self, tlist, node in self.original_top, node)
-        try:
-            task.make_ready()
-        except:
-            # We had a problem just trying to get this task ready (like
-            # a child couldn't be linked in to a VariantDir when deciding
-            # whether this node is current).  Arrange to raise the
-            # exception when the Task is "executed."
-            self.ready_exc = sys.exc_info()
-
-        if self.ready_exc:
-            task.exception_set(self.ready_exc)
-
-        self.ready_exc = None
-
-        return task
-
-    def will_not_build(self, nodes, node_func=lambda n: None):
-        """
-        Perform clean-up about nodes that will never be built. Invokes
-        a user defined function on all of these nodes (including all
-        of their parents).
-        """
-
-        T = self.trace
-
-        pending_children = self.pending_children
-
-        to_visit = set(nodes)
-        pending_children = pending_children - to_visit
-
-        if T:
-            for n in nodes:
-                T.write(self.trace_message('       removing node %s from the pending children set\n' %
-                        self.trace_node(n)))
-        try:
-            while len(to_visit):
-                node = to_visit.pop()
-                node_func(node)
-
-                # Prune recursion by flushing the waiting children
-                # list immediately.
-                parents = node.waiting_parents
-                node.waiting_parents = set()
-
-                to_visit = to_visit | parents
-                pending_children = pending_children - parents
-
-                for p in parents:
-                    p.ref_count = p.ref_count - 1
-                    if T: T.write(self.trace_message('       removing parent %s from the pending children set\n' %
-                                  self.trace_node(p)))
-        except KeyError:
-            # The container to_visit has been emptied.
-            pass
-
-        # We have the stick back the pending_children list into the
-        # taskmaster because the python 1.5.2 compatibility does not
-        # allow us to use in-place updates
-        self.pending_children = pending_children
-
-    def stop(self):
-        """
-        Stops the current build completely.
-        """
-        self.next_candidate = self.no_next_candidate
-
-    def cleanup(self):
-        """
-        Check for dependency cycles.
-        """
-        if not self.pending_children:
-            return
-
-        nclist = [(n, find_cycle([n], set())) for n in self.pending_children]
-
-        genuine_cycles = [
-            node for node,cycle in nclist
-                     if cycle or node.get_state() != NODE_EXECUTED
-        ]
-        if not genuine_cycles:
-            # All of the "cycles" found were single nodes in EXECUTED state,
-            # which is to say, they really weren't cycles.  Just return.
-            return
-
-        desc = 'Found dependency cycle(s):\n'
-        for node, cycle in nclist:
-            if cycle:
-                desc = desc + "  " + " -> ".join(map(str, cycle)) + "\n"
-            else:
-                desc = desc + \
-                    "  Internal Error: no cycle found for node %s (%s) in state %s\n" %  \
-                    (node, repr(node), StateString[node.get_state()])
-
-        raise SCons.Errors.UserError(desc)
-
-# Local Variables:
-# tab-width:4
-# indent-tabs-mode:nil
-# End:
-# vim: set expandtab tabstop=4 shiftwidth=4: