Give in and copy bjam into cdec source code

1 files changed, 1118 insertions, 0 deletions

diff --git a/jam-files/boost-build/build/virtual_target.py b/jam-files/boost-build/build/virtual_target.py
new file mode 100644
index 00000000..51dff037
--- /dev/null
+++ b/jam-files/boost-build/build/virtual_target.py
@@ -0,0 +1,1118 @@
+# Status: ported.
+# Base revision: 64488.
+# 
+#  Copyright (C) Vladimir Prus 2002. Permission to copy, use, modify, sell and
+#  distribute this software is granted provided this copyright notice appears in
+#  all copies. This software is provided "as is" without express or implied
+#  warranty, and with no claim as to its suitability for any purpose.
+
+#  Implements virtual targets, which correspond to actual files created during
+#  build, but are not yet targets in Jam sense. They are needed, for example,
+#  when searching for possible transormation sequences, when it's not known
+#  if particular target should be created at all.
+#
+#
+#                       +--------------------------+
+#                       | VirtualTarget           |
+#                       +==========================+
+#                       | actualize                |
+#                       +--------------------------+
+#                       | actualize_action() = 0   |
+#                       | actualize_location() = 0 |
+#                       +----------------+---------+
+#                                        |
+#                                        ^
+#                                       / \
+#                                      +-+-+
+#                                        |
+#    +---------------------+     +-------+--------------+
+#    | Action              |     | AbstractFileTarget   |
+#    +=====================|   * +======================+
+#    | action_name         |  +--+ action               |
+#    | properties          |  |  +----------------------+
+#    +---------------------+--+  | actualize_action()   |
+#    | actualize()         |0..1 +-----------+----------+
+#    | path()              |                 |
+#    | adjust_properties() | sources         |
+#    | actualize_sources() | targets         |
+#    +------+--------------+                 ^
+#           |                               / \
+#           ^                              +-+-+
+#          / \                               |
+#         +-+-+                +-------------+-------------+
+#           |                  |                           |
+#           |           +------+---------------+  +--------+-------------+
+#           |           | FileTarget           |  | SearchedLibTarget    |
+#           |           +======================+  +======================+
+#           |           | actualize-location() |  | actualize-location() |
+#           |           +----------------------+  +----------------------+
+#           |
+#         +-+------------------------------+
+#         |                                |
+#    +----+----------------+     +---------+-----------+
+#    | CompileAction       |     | LinkAction          |
+#    +=====================+     +=====================+
+#    | adjust_properties() |     | adjust_properties() |
+#    +---------------------+     | actualize_sources() |
+#                                +---------------------+
+#
+# The 'CompileAction' and 'LinkAction' classes are defined not here,
+# but in builtin.jam modules. They are shown in the diagram to give
+# the big picture.
+
+import bjam
+
+import re
+import os.path
+import string
+import types
+
+from b2.util import path, utility, set
+from b2.util.utility import add_grist, get_grist, ungrist, replace_grist, get_value
+from b2.util.sequence import unique
+from b2.tools import common
+from b2.exceptions import *
+import b2.build.type
+import b2.build.property_set as property_set
+
+import b2.build.property as property
+
+from b2.manager import get_manager
+from b2.util import bjam_signature
+
+__re_starts_with_at = re.compile ('^@(.*)')
+
+class VirtualTargetRegistry:
+    def __init__ (self, manager):
+        self.manager_ = manager
+        
+        # A cache for FileTargets
+        self.files_ = {}
+
+        # A cache for targets.
+        self.cache_ = {}
+
+        # A map of actual names to virtual targets.
+        # Used to make sure we don't associate same
+        # actual target to two virtual targets.
+        self.actual_ = {}
+
+        self.recent_targets_ = []
+        
+        # All targets ever registed
+        self.all_targets_ = []
+
+        self.next_id_ = 0
+        
+    def register (self, target):
+        """ Registers a new virtual target. Checks if there's already registered target, with the same
+            name, type, project and subvariant properties, and also with the same sources
+            and equal action. If such target is found it is retured and 'target' is not registered.
+            Otherwise, 'target' is registered and returned.
+        """
+        if target.path():
+            signature = target.path() + "-" + target.name()
+        else:
+            signature = "-" + target.name()
+
+        result = None
+        if not self.cache_.has_key (signature):
+            self.cache_ [signature] = []
+
+        for t in self.cache_ [signature]:
+            a1 = t.action ()
+            a2 = target.action ()
+
+            # TODO: why are we checking for not result?
+            if not result:
+                if not a1 and not a2:
+                    result = t
+                else:
+                    if a1 and a2 and a1.action_name () == a2.action_name () and a1.sources () == a2.sources ():
+                        ps1 = a1.properties ()
+                        ps2 = a2.properties ()
+                        p1 = ps1.base () + ps1.free () +\
+                            b2.util.set.difference(ps1.dependency(), ps1.incidental())
+                        p2 = ps2.base () + ps2.free () +\
+                            b2.util.set.difference(ps2.dependency(), ps2.incidental())
+                        if p1 == p2:
+                            result = t
+        
+        if not result:
+            self.cache_ [signature].append (target)
+            result = target
+
+        # TODO: Don't append if we found pre-existing target?
+        self.recent_targets_.append(result)
+        self.all_targets_.append(result)
+    
+        return result
+
+    def from_file (self, file, file_location, project):
+        """ Creates a virtual target with appropriate name and type from 'file'.
+            If a target with that name in that project was already created, returns that already
+            created target.
+            TODO: more correct way would be to compute path to the file, based on name and source location
+            for the project, and use that path to determine if the target was already created.
+            TODO: passing project with all virtual targets starts to be annoying.
+        """
+        # Check if we've created a target corresponding to this file.
+        path = os.path.join(os.getcwd(), file_location, file)
+        path = os.path.normpath(path)
+
+        if self.files_.has_key (path):
+            return self.files_ [path]
+
+        file_type = b2.build.type.type (file)
+
+        result = FileTarget (file, file_type, project,
+                             None, file_location)       
+        self.files_ [path] = result
+                
+        return result
+
+    def recent_targets(self):
+        """Each target returned by 'register' is added to a list of
+        'recent-target', returned by this function. So, this allows
+        us to find all targets created when building a given main
+        target, even if the target."""
+
+        return self.recent_targets_
+
+    def clear_recent_targets(self):
+        self.recent_targets_ = []
+
+    def all_targets(self):
+        # Returns all virtual targets ever created
+        return self.all_targets_
+
+    # Returns all targets from 'targets' with types
+    # equal to 'type' or derived from it.
+    def select_by_type(self, type, targets):
+        return [t for t in targets if b2.build.type.is_sybtype(t.type(), type)]
+
+    def register_actual_name (self, actual_name, virtual_target):
+        if self.actual_.has_key (actual_name):
+            cs1 = self.actual_ [actual_name].creating_subvariant ()
+            cs2 = virtual_target.creating_subvariant ()
+            cmt1 = cs1.main_target ()
+            cmt2 = cs2.main_target ()            
+            
+            action1 = self.actual_ [actual_name].action ()
+            action2 = virtual_target.action ()
+            
+            properties_added = []
+            properties_removed = []
+            if action1 and action2:
+                p1 = action1.properties ()
+                p1 = p1.raw ()
+                p2 = action2.properties ()
+                p2 = p2.raw ()
+                
+                properties_removed = set.difference (p1, p2)
+                if not properties_removed: properties_removed = "none"
+
+                properties_added = set.difference (p2, p1)
+                if not properties_added: properties_added = "none"
+
+            # FIXME: Revive printing of real location.
+            get_manager().errors()(
+                "Duplicate name of actual target: '%s'\n" 
+                "previous virtual target '%s'\n"
+                "created from '%s'\n"
+                "another virtual target '%s'\n"
+                "created from '%s'\n"
+                "added properties: '%s'\n"
+                "removed properties: '%s'\n"
+                % (actual_name,
+                   self.actual_ [actual_name], "loc", #cmt1.location (),
+                   virtual_target, 
+                   "loc", #cmt2.location (),
+                   properties_added, properties_removed))
+
+        else:
+            self.actual_ [actual_name] = virtual_target
+    
+
+    def add_suffix (self, specified_name, file_type, prop_set):
+        """ Appends the suffix appropriate to 'type/property_set' combination
+            to the specified name and returns the result.
+        """
+        suffix = b2.build.type.generated_target_suffix (file_type, prop_set)
+
+        if suffix:
+            return specified_name + '.' + suffix
+
+        else:
+            return specified_name
+    
+class VirtualTarget:
+    """ Potential target. It can be converted into jam target and used in
+        building, if needed. However, it can be also dropped, which allows
+        to search for different transformation and select only one.
+        name:    name of this target.
+        project: project to which this target belongs.
+    """
+    def __init__ (self, name, project):
+        self.name_ = name
+        self.project_ = project
+        self.dependencies_ = []
+        self.always_ = False
+        
+        # Caches if dapendencies for scanners have already been set.
+        self.made_ = {}
+
+    def manager(self):
+        return self.project_.manager()
+
+    def virtual_targets(self):
+        return self.manager().virtual_targets()
+
+    def name (self):
+        """ Name of this target.
+        """
+        return self.name_
+
+    def project (self):
+        """ Project of this target.
+        """
+        return self.project_
+
+    def depends (self, d):
+        """ Adds additional instances of 'VirtualTarget' that this
+            one depends on.
+        """
+        self.dependencies_ = unique (self.dependencies_ + d).sort ()
+
+    def dependencies (self):
+        return self.dependencies_
+
+    def always(self):
+        self.always_ = True
+
+    def actualize (self, scanner = None):
+        """ Generates all the actual targets and sets up build actions for
+            this target.
+            
+            If 'scanner' is specified, creates an additional target
+            with the same location as actual target, which will depend on the
+            actual target and be associated with 'scanner'. That additional
+            target is returned. See the docs (#dependency_scanning) for rationale.
+            Target must correspond to a file if 'scanner' is specified.
+            
+            If scanner is not specified, then actual target is returned.
+        """
+        actual_name = self.actualize_no_scanner ()
+
+        if self.always_:
+            bjam.call("ALWAYS", actual_name)
+
+        if not scanner:
+            return actual_name
+
+        else:
+            # Add the scanner instance to the grist for name.
+            g = '-'.join ([ungrist(get_grist(actual_name)), str(id(scanner))])
+
+            name = replace_grist (actual_name, '<' + g + '>')
+
+            if not self.made_.has_key (name):
+                self.made_ [name] = True
+
+                self.project_.manager ().engine ().add_dependency (name, actual_name)
+
+                self.actualize_location (name)
+
+                self.project_.manager ().scanners ().install (scanner, name, str (self))
+
+            return name
+
+# private: (overridables)
+
+    def actualize_action (self, target):
+        """ Sets up build actions for 'target'. Should call appropriate rules
+            and set target variables.
+        """
+        raise BaseException ("method should be defined in derived classes")
+
+    def actualize_location (self, target):
+        """ Sets up variables on 'target' which specify its location.
+        """
+        raise BaseException ("method should be defined in derived classes")
+    
+    def path (self):
+        """ If the target is generated one, returns the path where it will be
+            generated. Otherwise, returns empty list.
+        """
+        raise BaseException ("method should be defined in derived classes")
+    
+    def actual_name (self):
+        """ Return that actual target name that should be used
+            (for the case where no scanner is involved)
+        """
+        raise BaseException ("method should be defined in derived classes")
+
+
+class AbstractFileTarget (VirtualTarget):
+    """ Target which correspond to a file. The exact mapping for file
+        is not yet specified in this class. (TODO: Actually, the class name
+        could be better...)
+        
+        May be a source file (when no action is specified), or
+        derived file (otherwise).
+        
+        The target's grist is concatenation of project's location,
+        properties of action (for derived files), and, optionally,
+        value identifying the main target.
+        
+        exact:  If non-empty, the name is exactly the name
+                created file should have. Otherwise, the '__init__'
+                method will add suffix obtained from 'type' by
+                calling 'type.generated-target-suffix'.
+                  
+        type:   optional type of this target.
+    """
+    def __init__ (self, name, type, project, action = None, exact=False):
+        VirtualTarget.__init__ (self, name, project)
+            
+        self.type_ = type
+
+        self.action_ = action
+        self.exact_ = exact
+        
+        if action:
+            action.add_targets ([self])
+ 
+            if self.type and not exact:
+                self.__adjust_name (name)
+
+        
+        self.actual_name_ = None
+        self.path_ = None
+        self.intermediate_ = False
+        self.creating_subvariant_ = None
+        
+        # True if this is a root target.
+        self.root_ = False
+
+    def type (self):
+        return self.type_
+
+    def set_path (self, path):
+        """ Sets the path. When generating target name, it will override any path
+            computation from properties.
+        """
+        self.path_ = path
+
+    def action (self):
+        """ Returns the action.
+        """
+        return self.action_
+
+    def root (self, set = None):
+        """ Sets/gets the 'root' flag. Target is root is it directly correspods to some
+            variant of a main target.
+        """
+        if set:
+            self.root_ = True
+        return self.root_
+
+    def creating_subvariant (self, s = None):
+        """ Gets or sets the subvariant which created this target. Subvariant
+        is set when target is brought into existance, and is never changed
+        after that. In particual, if target is shared by subvariant, only 
+        the first is stored.
+        s:  If specified, specified the value to set,
+                which should be instance of 'subvariant' class.
+        """
+        if s and not self.creating_subvariant ():
+            if self.creating_subvariant ():
+                raise BaseException ("Attempt to change 'dg'")
+
+            else:
+                self.creating_subvariant_ = s
+
+        return self.creating_subvariant_
+
+    def actualize_action (self, target):
+        if self.action_:
+            self.action_.actualize ()
+
+    # Return a human-readable representation of this target
+    #
+    # If this target has an action, that's:
+    #
+    #    { <action-name>-<self.name>.<self.type> <action-sources>... }
+    #
+    # otherwise, it's:
+    #
+    #    { <self.name>.<self.type> }
+    #
+    def str(self):
+        a = self.action()
+
+        name_dot_type = self.name_ + "." + self.type_
+
+        if a:
+            action_name = a.action_name()
+            ss = [ s.str() for s in a.sources()]
+                       
+            return "{ %s-%s %s}" % (action_name, name_dot_type, str(ss))
+        else:
+            return "{ " + name_dot_type + " }"
+        
+# private:
+
+    def actual_name (self):
+        if not self.actual_name_:
+            self.actual_name_ = '<' + self.grist() + '>' + self.name_
+
+        return self.actual_name_
+
+    def grist (self):
+        """Helper to 'actual_name', above. Compute unique prefix used to distinguish
+            this target from other targets with the same name which create different
+            file.
+        """
+        # Depending on target, there may be different approaches to generating
+        # unique prefixes. We'll generate prefixes in the form 
+        # <one letter approach code> <the actual prefix>
+        path = self.path ()
+        
+        if path:
+            # The target will be generated to a known path. Just use the path
+            # for identification, since path is as unique as it can get.
+            return 'p' + path
+
+        else:
+            # File is either source, which will be searched for, or is not a file at
+            # all. Use the location of project for distinguishing.
+            project_location = self.project_.get ('location')
+            path_components = b2.util.path.split(project_location)
+            location_grist = '!'.join (path_components)
+            
+            if self.action_:
+                ps = self.action_.properties ()
+                property_grist = ps.as_path ()
+                # 'property_grist' can be empty when 'ps' is an empty
+                # property set.
+                if property_grist:
+                    location_grist = location_grist + '/' + property_grist
+                        
+            return 'l' + location_grist
+
+    def __adjust_name(self, specified_name):
+        """Given the target name specified in constructor, returns the
+        name which should be really used, by looking at the <tag> properties.
+        The tag properties come in two flavour:
+          - <tag>value, 
+          - <tag>@rule-name
+        In the first case, value is just added to name
+        In the second case, the specified rule is called with specified name,
+        target type and properties and should return the new name.
+        If not <tag> property is specified, or the rule specified by
+        <tag> returns nothing, returns the result of calling 
+        virtual-target.add-suffix"""
+
+        if self.action_:
+            ps = self.action_.properties()
+        else:
+            ps = property_set.empty()
+
+        # FIXME: I'm not sure how this is used, need to check with
+        # Rene to figure out how to implement
+        #~ We add ourselves to the properties so that any tag rule can get
+        #~ more direct information about the target than just that available
+        #~ through the properties. This is useful in implementing
+        #~ name changes based on the sources of the target. For example to
+        #~ make unique names of object files based on the source file.
+        #~ --grafik
+        #ps = property_set.create(ps.raw() + ["<target>%s" % "XXXX"])
+        #ps = [ property-set.create [ $(ps).raw ] <target>$(__name__) ] ;
+        
+        tag = ps.get("<tag>")
+        
+        if tag:
+
+            if len(tag) > 1:
+                get_manager().errors()(
+                    """<tag>@rulename is present but is not the only <tag> feature""")
+
+            tag = tag[0]
+            if callable(tag):
+                self.name_ = tag(specified_name, self.type_, ps)
+            else:
+                if not tag[0] == '@':
+                    self.manager_.errors()("""The value of the <tag> feature must be '@rule-nane'""")
+
+                exported_ps = b2.util.value_to_jam(ps, methods=True)
+                self.name_ = b2.util.call_jam_function(
+                    tag[1:], specified_name, self.type_, exported_ps)
+                if self.name_:
+                    self.name_ = self.name_[0]
+        
+        # If there's no tag or the tag rule returned nothing.
+        if not tag or not self.name_:
+            self.name_ = add_prefix_and_suffix(specified_name, self.type_, ps)
+
+    def actualize_no_scanner(self):
+        name = self.actual_name()
+
+        # Do anything only on the first invocation
+        if not self.made_:
+            self.made_[name] = True
+
+            if self.action_:  
+                # For non-derived target, we don't care if there
+                # are several virtual targets that refer to the same name.
+                # One case when this is unavoidable is when file name is
+                # main.cpp and two targets have types CPP (for compiling)
+                # and MOCCABLE_CPP (for convertion to H via Qt tools).
+                self.virtual_targets().register_actual_name(name, self)
+
+            for i in self.dependencies_:
+                self.manager_.engine().add_dependency(name, i.actualize())
+
+            self.actualize_location(name)
+            self.actualize_action(name)
+            
+        return name
+
+@bjam_signature((["specified_name"], ["type"], ["property_set"]))
+def add_prefix_and_suffix(specified_name, type, property_set):
+    """Appends the suffix appropriate to 'type/property-set' combination
+    to the specified name and returns the result."""
+
+    property_set = b2.util.jam_to_value_maybe(property_set)
+
+    suffix = ""
+    if type:
+        suffix = b2.build.type.generated_target_suffix(type, property_set)
+    
+    # Handle suffixes for which no leading dot is desired.  Those are
+    # specified by enclosing them in <...>.  Needed by python so it
+    # can create "_d.so" extensions, for example.
+    if get_grist(suffix):
+        suffix = ungrist(suffix)
+    elif suffix:
+        suffix = "." + suffix
+
+    prefix = ""
+    if type:
+        prefix = b2.build.type.generated_target_prefix(type, property_set)
+
+    if specified_name.startswith(prefix):
+        prefix = ""
+
+    if not prefix:
+        prefix = ""
+    if not suffix:
+        suffix = ""
+    return prefix + specified_name + suffix
+
+
+class FileTarget (AbstractFileTarget):
+    """ File target with explicitly known location.
+
+        The file path is determined as
+           - value passed to the 'set_path' method, if any
+           - for derived files, project's build dir, joined with components
+             that describe action's properties. If the free properties
+             are not equal to the project's reference properties
+             an element with name of main target is added.
+           - for source files, project's source dir
+        
+        The file suffix is
+            - the value passed to the 'suffix' method, if any, or
+            - the suffix which correspond to the target's type.
+    """
+    def __init__ (self, name, type, project, action = None, path=None, exact=False):
+        AbstractFileTarget.__init__ (self, name, type, project, action, exact)
+
+        self.path_ = path
+
+    def __str__(self):
+        if self.type_:
+            return self.name_ + "." + self.type_
+        else:
+            return self.name_
+
+    def clone_with_different_type(self, new_type):
+        return FileTarget(self.name_, new_type, self.project_,
+                          self.action_, self.path_, exact=True)
+        
+    def actualize_location (self, target):
+        engine = self.project_.manager_.engine ()
+
+        if self.action_:
+            # This is a derived file.
+            path = self.path ()
+            engine.set_target_variable (target, 'LOCATE', path)
+
+            # Make sure the path exists.
+            engine.add_dependency (target, path)
+            common.mkdir(engine, path)
+
+            # It's possible that the target name includes a directory
+            # too, for example when installing headers. Create that
+            # directory.
+            d = os.path.dirname(get_value(target))
+            if d:
+                d = os.path.join(path, d)
+                engine.add_dependency(target, d)
+                common.mkdir(engine, d)
+
+            # For real file target, we create a fake target that
+            # depends on the real target. This allows to run
+            #
+            #    bjam hello.o
+            #
+            # without trying to guess the name of the real target.            
+            # Note the that target has no directory name, and a special
+            # grist <e>.
+            #
+            # First, that means that "bjam hello.o" will build all
+            # known hello.o targets.
+            # Second, the <e> grist makes sure this target won't be confused
+            # with other targets, for example, if we have subdir 'test'
+            # with target 'test' in it that includes 'test.o' file,
+            # then the target for directory will be just 'test' the target
+            # for test.o will be <ptest/bin/gcc/debug>test.o and the target
+            # we create below will be <e>test.o
+            engine.add_dependency("<e>%s" % get_value(target), target)
+
+            # Allow bjam <path-to-file>/<file> to work.  This won't catch all
+            # possible ways to refer to the path (relative/absolute, extra ".",
+            # various "..", but should help in obvious cases.
+            engine.add_dependency("<e>%s" % (os.path.join(path, get_value(target))), target)
+            
+        else:
+            # This is a source file.
+            engine.set_target_variable (target, 'SEARCH', self.project_.get ('source-location'))
+    
+
+    def path (self):
+        """ Returns the directory for this target.
+        """
+        if not self.path_:
+            if self.action_:
+                p = self.action_.properties ()            
+                (target_path, relative_to_build_dir) = p.target_path ()
+                
+                if relative_to_build_dir:
+                    # Indicates that the path is relative to
+                    # build dir.
+                    target_path = os.path.join (self.project_.build_dir (), target_path)
+                                
+                # Store the computed path, so that it's not recomputed
+                # any more
+                self.path_ = target_path
+
+        return self.path_
+
+
+class NotFileTarget(AbstractFileTarget):
+
+    def __init__(self, name, project, action):
+        AbstractFileTarget.__init__(self, name, None, project, action)
+
+    def path(self):
+        """Returns nothing, to indicate that target path is not known."""
+        return None
+
+    def actualize_location(self, target):
+        bjam.call("NOTFILE", target)
+        bjam.call("ALWAYS", target)
+        bjam.call("NOUPDATE", target)
+
+
+class Action:
+    """ Class which represents an action.
+        Both 'targets' and 'sources' should list instances of 'VirtualTarget'.
+        Action name should name a rule with this prototype
+            rule action_name ( targets + : sources * : properties * )
+        Targets and sources are passed as actual jam targets. The rule may
+        not establish dependency relationship, but should do everything else.
+    """
+    def __init__ (self, manager, sources, action_name, prop_set):
+        assert(isinstance(prop_set, property_set.PropertySet))
+        assert type(sources) == types.ListType
+        self.sources_ = sources
+        self.action_name_ = action_name
+        if not prop_set:
+            prop_set = property_set.empty()
+        self.properties_ = prop_set
+        if not all(isinstance(v, VirtualTarget) for v in prop_set.get('implicit-dependency')):
+            import pdb
+            pdb.set_trace()
+
+        self.manager_ = manager
+        self.engine_ = self.manager_.engine ()
+        self.targets_ = []
+
+        # Indicates whether this has been actualized or not.
+        self.actualized_ = False
+        
+        self.dependency_only_sources_ = []
+        self.actual_sources_ = []
+        
+        
+    def add_targets (self, targets):
+        self.targets_ += targets
+
+
+    def replace_targets (old_targets, new_targets):
+        self.targets_ = [t for t in targets if not t in old_targets] + new_targets
+
+    def targets (self):
+        return self.targets_
+
+    def sources (self):
+        return self.sources_
+
+    def action_name (self):
+        return self.action_name_
+
+    def properties (self):
+        return self.properties_
+
+    def actualize (self):
+        """ Generates actual build instructions.
+        """
+        if self.actualized_:
+            return
+            
+        self.actualized_ = True
+
+        ps = self.properties ()
+        properties = self.adjust_properties (ps)
+
+
+        actual_targets = []
+        
+        for i in self.targets ():
+            actual_targets.append (i.actualize ())
+
+        self.actualize_sources (self.sources (), properties)
+
+        self.engine_.add_dependency (actual_targets, self.actual_sources_ + self.dependency_only_sources_)
+
+        # This works around a bug with -j and actions that
+        # produce multiple target, where:
+        # - dependency on the first output is found, and
+        #   the action is started
+        # - dependency on the second output is found, and
+        #   bjam noticed that command is already running
+        # - instead of waiting for the command, dependents
+        #   of the second targets are immediately updated.
+        if len(actual_targets) > 1:
+            bjam.call("INCLUDES", actual_targets, actual_targets)
+
+        # FIXME: check the comment below. Was self.action_name_ [1]
+        # Action name can include additional argument to rule, which should not
+        # be passed to 'set-target-variables'
+        # FIXME: breaking circular dependency
+        import toolset
+        toolset.set_target_variables (self.manager_, self.action_name_, actual_targets, properties)
+             
+        engine = self.manager_.engine ()
+
+        # FIXME: this is supposed to help --out-xml option, but we don't
+        # implement that now, and anyway, we should handle it in Python,
+        # not but putting variables on bjam-level targets.
+        bjam.call("set-target-variable", actual_targets, ".action", repr(self))
+        
+        self.manager_.engine ().set_update_action (self.action_name_, actual_targets, self.actual_sources_,
+                                                   properties)
+        
+        # Since we set up creating action here, we also set up
+        # action for cleaning up
+        self.manager_.engine ().set_update_action ('common.Clean', 'clean-all',
+                                                   actual_targets)
+
+        return actual_targets
+
+    def actualize_source_type (self, sources, prop_set):
+        """ Helper for 'actualize_sources'.
+            For each passed source, actualizes it with the appropriate scanner.
+            Returns the actualized virtual targets.
+        """
+        result = []
+        for i in sources:
+            scanner = None
+
+# FIXME: what's this?
+#            if isinstance (i, str):
+#                i = self.manager_.get_object (i)
+                
+            if i.type ():
+                scanner = b2.build.type.get_scanner (i.type (), prop_set)
+
+            r = i.actualize (scanner)
+            result.append (r)
+        
+        return result
+    
+    def actualize_sources (self, sources, prop_set):
+        """ Creates actual jam targets for sources. Initializes two member
+            variables:
+            'self.actual_sources_' -- sources which are passed to updating action
+            'self.dependency_only_sources_' -- sources which are made dependencies, but
+            are not used otherwise.
+            
+            New values will be *appended* to the variables. They may be non-empty,
+            if caller wants it.
+        """
+        dependencies = self.properties_.get ('<dependency>')
+                
+        self.dependency_only_sources_ += self.actualize_source_type (dependencies, prop_set)
+        self.actual_sources_ += self.actualize_source_type (sources, prop_set)
+
+        # This is used to help bjam find dependencies in generated headers
+        # in other main targets.
+        # Say:
+        #
+        #   make a.h : ....... ;
+        #   exe hello : hello.cpp : <implicit-dependency>a.h ;
+        #
+        # However, for bjam to find the dependency the generated target must
+        # be actualized (i.e. have the jam target). In the above case,
+        # if we're building just hello ("bjam hello"), 'a.h' won't be
+        # actualized unless we do it here.
+        implicit = self.properties_.get("<implicit-dependency>")
+
+        for i in implicit:
+            i.actualize()
+
+    def adjust_properties (self, prop_set):
+        """ Determines real properties when trying building with 'properties'.
+            This is last chance to fix properties, for example to adjust includes
+            to get generated headers correctly. Default implementation returns
+            its argument.
+        """
+        return prop_set
+
+
+class NullAction (Action):
+    """ Action class which does nothing --- it produces the targets with
+        specific properties out of nowhere. It's needed to distinguish virtual
+        targets with different properties that are known to exist, and have no 
+        actions which create them.
+    """
+    def __init__ (self, manager, prop_set):
+        Action.__init__ (self, manager, [], None, prop_set)
+        
+    def actualize (self):
+        if not self.actualized_:
+            self.actualized_ = True
+
+            for i in self.targets ():
+                i.actualize ()
+
+class NonScanningAction(Action):
+    """Class which acts exactly like 'action', except that the sources
+    are not scanned for dependencies."""
+
+    def __init__(self, sources, action_name, property_set):
+        #FIXME: should the manager parameter of Action.__init__
+        #be removed? -- Steven Watanabe
+        Action.__init__(self, b2.manager.get_manager(), sources, action_name, property_set)
+
+    def actualize_source_type(self, sources, property_set):
+
+        result = []
+        for s in sources:
+            result.append(s.actualize())
+        return result
+
+def traverse (target, include_roots = False, include_sources = False):
+    """ Traverses the dependency graph of 'target' and return all targets that will
+        be created before this one is created. If root of some dependency graph is
+        found during traversal, it's either included or not, dependencing of the
+        value of 'include_roots'. In either case, sources of root are not traversed.
+    """
+    result = []
+    
+    if target.action ():
+        action = target.action ()
+        
+        # This includes 'target' as well
+        result += action.targets ()
+
+        for t in action.sources ():
+
+            # FIXME:
+            # TODO: see comment in Manager.register_object ()
+            #if not isinstance (t, VirtualTarget):
+            #    t = target.project_.manager_.get_object (t)
+                
+            if not t.root ():
+                result += traverse (t, include_roots, include_sources)
+
+            elif include_roots:
+                result.append (t)
+
+    elif include_sources:
+        result.append (target)
+
+    return result
+
+def clone_action (action, new_project, new_action_name, new_properties):
+    """Takes an 'action' instances and creates new instance of it
+    and all produced target. The rule-name and properties are set
+    to 'new-rule-name' and 'new-properties', if those are specified.
+    Returns the cloned action."""
+
+    if not new_action_name:
+        new_action_name = action.action_name()
+
+    if not new_properties:
+        new_properties = action.properties()
+
+    cloned_action = action.__class__(action.manager_, action.sources(), new_action_name,
+                                     new_properties)
+                          
+    cloned_targets = []
+    for target in action.targets():
+
+        n = target.name()
+        # Don't modify the name of the produced targets. Strip the directory f
+        cloned_target = FileTarget(n, target.type(), new_project,
+                                   cloned_action, exact=True)
+
+        d = target.dependencies()
+        if d:
+            cloned_target.depends(d)
+        cloned_target.root(target.root())
+        cloned_target.creating_subvariant(target.creating_subvariant())
+
+        cloned_targets.append(cloned_target)
+
+    return cloned_action
+
+class Subvariant:
+    
+    def __init__ (self, main_target, prop_set, sources, build_properties, sources_usage_requirements, created_targets):
+        """ 
+        main_target:                 The instance of MainTarget class
+        prop_set:                    Properties requested for this target
+        sources:
+        build_properties:            Actually used properties
+        sources_usage_requirements:  Properties propagated from sources
+        created_targets:             Top-level created targets
+        """
+        self.main_target_ = main_target
+        self.properties_ = prop_set
+        self.sources_ = sources
+        self.build_properties_ = build_properties
+        self.sources_usage_requirements_ = sources_usage_requirements
+        self.created_targets_ = created_targets
+
+        self.usage_requirements_ = None
+        
+        # Pre-compose the list of other dependency graphs, on which this one
+        # depends
+        deps = build_properties.get('<implicit-dependency>')
+        
+        self.other_dg_ = []
+        for d in deps:
+            self.other_dg_.append(d.creating_subvariant ())
+
+        self.other_dg_ = unique (self.other_dg_)
+
+        self.implicit_includes_cache_ = {}
+        self.target_directories_ = None
+               
+    def main_target (self):
+        return self.main_target_
+    
+    def created_targets (self):
+        return self.created_targets_
+    
+    def requested_properties (self):
+        return self.properties_
+    
+    def build_properties (self):
+        return self.build_properties_
+    
+    def sources_usage_requirements (self):
+        return self.sources_usage_requirements_
+    
+    def set_usage_requirements (self, usage_requirements):
+        self.usage_requirements_ = usage_requirements
+    
+    def usage_requirements (self):
+        return self.usage_requirements_
+
+    def all_referenced_targets(self, result):
+        """Returns all targets referenced by this subvariant,
+        either directly or indirectly, and either as sources,
+        or as dependency properties. Targets referred with
+        dependency property are returned a properties, not targets."""
+
+        # Find directly referenced targets.
+        deps = self.build_properties().dependency()
+        all_targets = self.sources_ + deps
+        
+        # Find other subvariants.
+        r = []
+        for e in all_targets:
+            if not e in result:
+                result.add(e)
+                if isinstance(e, property.Property):
+                    t = e.value()
+                else:
+                    t = e
+                                    
+                # FIXME: how can this be?
+                cs = t.creating_subvariant()
+                if cs:
+                    r.append(cs)
+        r = unique(r)
+        for s in r:
+            if s != self:
+                s.all_referenced_targets(result)
+
+
+    def implicit_includes (self, feature, target_type):
+        """ Returns the properties which specify implicit include paths to
+            generated headers. This traverses all targets in this subvariant,
+            and subvariants referred by <implcit-dependecy>properties.
+            For all targets which are of type 'target-type' (or for all targets,
+            if 'target_type' is not specified), the result will contain
+            <$(feature)>path-to-that-target.
+        """
+
+        if not target_type:
+            key = feature
+        else:
+            key = feature + "-" + target_type
+
+            
+        result = self.implicit_includes_cache_.get(key)
+        if not result:
+            target_paths = self.all_target_directories(target_type)
+            target_paths = unique(target_paths)
+            result = ["<%s>%s" % (feature, p) for p in target_paths]
+            self.implicit_includes_cache_[key] = result
+
+        return result
+
+    def all_target_directories(self, target_type = None):
+        # TODO: does not appear to use target_type in deciding
+        # if we've computed this already.
+        if not self.target_directories_:
+            self.target_directories_ = self.compute_target_directories(target_type)
+        return self.target_directories_
+
+    def compute_target_directories(self, target_type=None):
+        result = []
+        for t in self.created_targets():
+            if not target_type or b2.build.type.is_derived(t.type(), target_type):
+                result.append(t.path())
+
+        for d in self.other_dg_:
+            result.extend(d.all_target_directories(target_type))
+
+        result = unique(result)
+        return result