3 The Node package for the SCons software construction utility.
5 This is, in many ways, the heart of SCons.
7 A Node is where we encapsulate all of the dependency information about
8 any thing that SCons can build, or about any thing which SCons can use
9 to build some other thing. The canonical "thing," of course, is a file,
10 but a Node can also represent something remote (like a web page) or
11 something completely abstract (like an Alias).
13 Each specific type of "thing" is specifically represented by a subclass
14 of the Node base class: Node.FS.File for files, Node.Alias for aliases,
15 etc. Dependency information is kept here in the base class, and
16 information specific to files/aliases/etc. is in the subclass. The
17 goal, if we've done this correctly, is that any type of "thing" should
18 be able to depend on any other type of "thing."
25 # Permission is hereby granted, free of charge, to any person obtaining
26 # a copy of this software and associated documentation files (the
27 # "Software"), to deal in the Software without restriction, including
28 # without limitation the rights to use, copy, modify, merge, publish,
29 # distribute, sublicense, and/or sell copies of the Software, and to
30 # permit persons to whom the Software is furnished to do so, subject to
31 # the following conditions:
33 # The above copyright notice and this permission notice shall be included
34 # in all copies or substantial portions of the Software.
36 # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
37 # KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
38 # WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
39 # NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
40 # LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
41 # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
42 # WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
45 __revision__ = "__FILE__ __REVISION__ __DATE__ __DEVELOPER__"
53 from SCons.Debug import logInstanceCreation
60 # These are in "priority" order, so that the maximum value for any
61 # child/dependency of a node represents the state of that node if
62 # it has no builder of its own. The canonical example is a file
63 # system directory, which is only up to date if all of its children
71 stack = 6 # nodes that are in the current Taskmaster execution stack
83 # controls whether implicit dependencies are cached:
86 # controls whether implicit dep changes are ignored:
87 implicit_deps_unchanged = 0
89 # controls whether the cached implicit deps are ignored:
90 implicit_deps_changed = 0
92 # A variable that can be set to an interface-specific function be called
93 # to annotate a Node with information about its creation.
94 def do_nothing(node): pass
99 def __cmp__(self, other):
100 return cmp(self.__dict__, other.__dict__)
103 """The base Node class, for entities that we know how to
104 build, or use to build other Nodes.
107 __metaclass__ = SCons.Memoize.Memoized_Metaclass
113 if __debug__: logInstanceCreation(self, 'Node.Node')
114 # Note that we no longer explicitly initialize a self.builder
115 # attribute to None here. That's because the self.builder
116 # attribute may be created on-the-fly later by a subclass (the
117 # canonical example being a builder to fetch a file from a
118 # source code system like CVS or Subversion).
120 # Each list of children that we maintain is accompanied by a
121 # dictionary used to look up quickly whether a node is already
122 # present in the list. Empirical tests showed that it was
123 # fastest to maintain them as side-by-side Node attributes in
124 # this way, instead of wrapping up each list+dictionary pair in
125 # a class. (Of course, we could always still do that in the
126 # future if we had a good reason to...).
127 self.sources = [] # source files used to build node
128 self.sources_dict = {}
129 self.depends = [] # explicit dependencies (from Depends)
130 self.depends_dict = {}
131 self.ignore = [] # dependencies to ignore
132 self.ignore_dict = {}
133 self.implicit = None # implicit (scanned) dependencies (None means not scanned yet)
134 self.waiting_parents = []
135 self.wkids = None # Kids yet to walk, when it's an array
138 self.state = no_state
140 self.always_build = None
141 self.found_includes = {}
143 self.attributes = self.Attrs() # Generic place to stick information about the Node.
144 self.side_effect = 0 # true iff this node is a side effect
145 self.side_effects = [] # the side effects of building this target
146 self.pre_actions = []
147 self.post_actions = []
148 self.linked = 0 # is this node linked to the build directory?
150 # Let the interface in which the build engine is embedded
151 # annotate this Node with its own info (like a description of
152 # what line in what file created the node, for example).
155 def get_suffix(self):
158 def get_build_env(self):
159 """Fetch the appropriate Environment to build this node.
161 return self.get_executor().get_build_env()
163 def get_build_scanner_path(self, scanner):
164 """Fetch the appropriate scanner path for this node."""
165 return self.get_executor().get_build_scanner_path(scanner)
167 def set_executor(self, executor):
168 """Set the action executor for this node."""
169 self.executor = executor
171 def get_executor(self, create=1):
172 """Fetch the action executor for this node. Create one if
173 there isn't already one, and requested to do so."""
175 executor = self.executor
176 except AttributeError:
180 act = self.builder.action
181 except AttributeError:
182 executor = SCons.Executor.Null()
185 act = self.pre_actions + act
186 if self.post_actions:
187 act = act + self.post_actions
188 executor = SCons.Executor.Executor(act,
189 self.env or self.builder.env,
190 [self.builder.overrides],
193 self.executor = executor
196 def executor_cleanup(self):
197 """Let the executor clean up any cached information."""
199 executor = self.get_executor(create=None)
200 except AttributeError:
205 def reset_executor(self):
206 "Remove cached executor; forces recompute when needed."
208 delattr(self, 'executor')
209 except AttributeError:
212 def retrieve_from_cache(self):
213 """Try to retrieve the node's content from a cache
215 This method is called from multiple threads in a parallel build,
216 so only do thread safe stuff here. Do thread unsafe stuff in
219 Returns true iff the node was successfully retrieved.
223 def build(self, **kw):
224 """Actually build the node.
226 This method is called from multiple threads in a parallel build,
227 so only do thread safe stuff here. Do thread unsafe stuff in
230 def errfunc(stat, node=self):
231 raise SCons.Errors.BuildError(node=node, errstr="Error %d" % stat)
232 executor = self.get_executor()
233 apply(executor, (self, errfunc), kw)
236 """Called just after this node is successfully built."""
238 # Clear the implicit dependency caches of any Nodes
239 # waiting for this Node to be built.
240 for parent in self.waiting_parents:
241 parent.implicit = None
245 new_binfo = self.binfo
246 except AttributeError:
247 # Node arrived here without build info; apparently it
248 # doesn't need it, so don't bother calculating or storing
252 # Reset this Node's cached state since it was just built and
253 # various state has changed.
256 # Had build info, so it should be stored in the signature
257 # cache. However, if the build info included a content
258 # signature then it should be recalculated before being
262 if hasattr(new_binfo, 'csig'):
263 new_binfo = self.gen_binfo() # sets self.binfo
265 self.binfo = new_binfo
266 self.store_info(new_binfo)
268 def add_to_waiting_parents(self, node):
269 self.waiting_parents.append(node)
271 def call_for_all_waiting_parents(self, func):
273 for parent in self.waiting_parents:
274 parent.call_for_all_waiting_parents(func)
276 def postprocess(self):
277 """Clean up anything we don't need to hang onto after we've
279 self.executor_cleanup()
282 """Completely clear a Node of all its cached state (so that it
283 can be re-evaluated by interfaces that do continuous integration
287 self.executor_cleanup()
291 delattr(self, '_calculated_sig')
292 except AttributeError:
295 self.found_includes = {}
298 self.waiting_parents = []
301 """Called just after this node has been visited
302 without requiring a build.."""
305 def builder_set(self, builder):
307 self.builder = builder
309 def has_builder(self):
310 """Return whether this Node has a builder or not.
312 In Boolean tests, this turns out to be a *lot* more efficient
313 than simply examining the builder attribute directly ("if
314 node.builder: ..."). When the builder attribute is examined
315 directly, it ends up calling __getattr__ for both the __len__
316 and __nonzero__ attributes on instances of our Builder Proxy
317 class(es), generating a bazillion extra calls and slowing
318 things down immensely.
322 except AttributeError:
323 # There was no explicit builder for this Node, so initialize
324 # the self.builder attribute to None now.
329 def set_explicit(self, is_explicit):
330 self.is_explicit = is_explicit
332 def has_explicit_builder(self):
333 """Return whether this Node has an explicit builder
335 This allows an internal Builder created by SCons to be marked
336 non-explicit, so that it can be overridden by an explicit
337 builder that the user supplies (the canonical example being
340 return self.is_explicit
341 except AttributeError:
342 self.is_explicit = None
343 return self.is_explicit
345 def get_builder(self, default_builder=None):
346 """Return the set builder, or a specified default value"""
349 except AttributeError:
350 return default_builder
352 multiple_side_effect_has_builder = has_builder
354 def is_derived(self):
356 Returns true iff this node is derived (i.e. built).
358 This should return true only for nodes whose path should be in
359 the build directory when duplicate=0 and should contribute their build
360 signatures when they are used as source files to other derived files. For
361 example: source with source builders are not derived in this sense,
362 and hence should not return true.
365 return self.has_builder() or self.side_effect
367 def is_pseudo_derived(self):
369 Returns true iff this node is built, but should use a source path
370 when duplicate=0 and should contribute a content signature (i.e.
371 source signature) when used as a source for other derived files.
375 def alter_targets(self):
376 """Return a list of alternate targets for this Node.
380 def get_found_includes(self, env, scanner, path):
381 """Return the scanned include lines (implicit dependencies)
384 The default is no implicit dependencies. We expect this method
385 to be overridden by any subclass that can be scanned for
386 implicit dependencies.
390 def get_implicit_deps(self, env, scanner, path):
391 """Return a list of implicit dependencies for this node.
393 This method exists to handle recursive invocation of the scanner
394 on the implicit dependencies returned by the scanner, if the
395 scanner's recursive flag says that we should.
400 # Give the scanner a chance to select a more specific scanner
402 scanner = scanner.select(self)
410 d = filter(lambda x, seen=seen: not seen.has_key(x),
411 n.get_found_includes(env, scanner, path))
416 nodes.extend(scanner.recurse_nodes(d))
420 def get_scanner(self, env, kw={}):
421 return env.get_scanner(self.scanner_key())
423 def get_source_scanner(self, node):
424 """Fetch the source scanner for the specified node
426 NOTE: "self" is the target being built, "node" is
427 the source file for which we want to fetch the scanner.
429 Implies self.has_builder() is true; again, expect to only be
430 called from locations where this is already verified.
432 This function may be called very often; it attempts to cache
433 the scanner found to improve performance.
437 scanner = self.builder.source_scanner
438 except AttributeError:
441 # The builder didn't have an explicit scanner, so go look up
442 # a scanner from env['SCANNERS'] based on the node's scanner
443 # key (usually the file extension).
444 scanner = self.get_scanner(self.get_build_env())
446 scanner = scanner.select(node)
449 def add_to_implicit(self, deps):
450 if not hasattr(self, 'implicit') or self.implicit is None:
452 self.implicit_dict = {}
453 self._children_reset()
454 self._add_child(self.implicit, self.implicit_dict, deps)
457 """Scan this node's dependents for implicit dependencies."""
458 # Don't bother scanning non-derived files, because we don't
459 # care what their dependencies are.
460 # Don't scan again, if we already have scanned.
461 if not self.implicit is None:
464 self.implicit_dict = {}
465 self._children_reset()
466 if not self.has_builder():
469 build_env = self.get_build_env()
471 # Here's where we implement --implicit-cache.
472 if implicit_cache and not implicit_deps_changed:
473 implicit = self.get_stored_implicit()
475 factory = build_env.get_factory(self.builder.source_factory)
476 implicit = map(factory, implicit)
477 self._add_child(self.implicit, self.implicit_dict, implicit)
478 calc = build_env.get_calculator()
479 if implicit_deps_unchanged or self.current(calc):
481 # one of this node's sources has changed, so
482 # we need to recalculate the implicit deps,
485 self.implicit_dict = {}
486 self._children_reset()
489 executor = self.get_executor()
491 # Have the executor scan the sources.
492 executor.scan_sources(self.builder.source_scanner)
494 # If there's a target scanner, have the executor scan the target
495 # node itself and associated targets that might be built.
496 scanner = self.builder.target_scanner
498 executor.scan_targets(scanner)
500 def scanner_key(self):
503 def env_set(self, env, safe=0):
504 if safe and self.env:
508 def calculator(self):
509 import SCons.Defaults
511 env = self.env or SCons.Defaults.DefaultEnvironment()
512 return env.get_calculator()
514 def calc_signature(self, calc=None):
516 Select and calculate the appropriate build signature for a node.
520 calc - the signature calculation module
521 returns - the signature
523 if self.is_derived():
524 import SCons.Defaults
526 env = self.env or SCons.Defaults.DefaultEnvironment()
527 if env.use_build_signature():
528 return self.calc_bsig(calc)
529 elif not self.rexists():
531 return self.calc_csig(calc)
537 """Delete the bsig from this node."""
539 delattr(self, 'binfo')
540 except AttributeError:
543 def calc_bsig(self, calc=None):
545 return self.binfo.bsig
546 except AttributeError:
547 self.binfo = self.gen_binfo(calc)
548 return self.binfo.bsig
550 def gen_binfo(self, calc=None, scan=1):
552 Generate a node's build signature, the digested signatures
553 of its dependency files and build information.
555 node - the node whose sources will be collected
556 cache - alternate node to use for the signature cache
557 returns - the build signature
559 This no longer handles the recursive descent of the
560 node's children's signatures. We expect that they're
561 already built and updated by someone else, if that's
567 calc = self.calculator()
569 binfo = self.new_binfo()
574 executor = self.get_executor()
575 def calc_signature(node, calc=calc):
576 return node.calc_signature(calc)
578 bsources = executor.process_sources(self.rel_path, self.ignore)
579 sourcesigs = executor.process_sources(calc_signature, self.ignore)
581 depends = self.depends
582 implicit = self.implicit or []
585 depends = filter(self.do_not_ignore, depends)
586 implicit = filter(self.do_not_ignore, implicit)
588 dependsigs = map(calc_signature, depends)
589 implicitsigs = map(calc_signature, implicit)
591 sigs = sourcesigs + dependsigs + implicitsigs
593 if self.has_builder():
594 binfo.bact = str(executor)
595 binfo.bactsig = calc.module.signature(executor)
596 sigs.append(binfo.bactsig)
598 binfo.bsources = bsources
599 binfo.bdepends = map(self.rel_path, depends)
600 binfo.bimplicit = map(self.rel_path, implicit)
602 binfo.bsourcesigs = sourcesigs
603 binfo.bdependsigs = dependsigs
604 binfo.bimplicitsigs = implicitsigs
606 binfo.bsig = calc.module.collect(filter(None, sigs))
610 def rel_path(self, other):
616 except AttributeError:
619 def calc_csig(self, calc=None):
622 except AttributeError:
623 binfo = self.binfo = self.new_binfo()
626 except AttributeError:
628 calc = self.calculator()
629 binfo.csig = calc.module.signature(self)
630 self.store_info(binfo)
633 def store_info(self, obj):
634 """Make the build signature permanent (that is, store it in the
635 .sconsign file or equivalent)."""
638 def get_stored_info(self):
641 def get_stored_implicit(self):
642 """Fetch the stored implicit dependencies"""
645 def set_precious(self, precious = 1):
646 """Set the Node's precious value."""
647 self.precious = precious
649 def set_always_build(self, always_build = 1):
650 """Set the Node's always_build value."""
651 self.always_build = always_build
654 """Does this node exists?"""
655 # All node exist by default:
659 """Does this node exist locally or in a repositiory?"""
660 # There are no repositories by default:
665 return not self.is_derived() and \
666 not self.is_pseudo_derived() and \
667 not self.linked and \
671 """Prepare for this Node to be created.
672 The default implemenation checks that all children either exist
676 if not self.implicit is None:
677 l = l + self.implicit
678 missing_sources = self.get_executor().get_missing_sources() \
679 + filter(lambda c: c.missing(), l)
681 desc = "Source `%s' not found, needed by target `%s'." % (missing_sources[0], self)
682 raise SCons.Errors.StopError, desc
685 """Remove this Node: no-op by default."""
688 def add_dependency(self, depend):
689 """Adds dependencies."""
691 self._add_child(self.depends, self.depends_dict, depend)
694 if SCons.Util.is_List(e):
698 raise SCons.Errors.UserError("attempted to add a non-Node dependency to %s:\n\t%s is a %s, not a Node" % (str(self), s, type(e)))
700 def add_ignore(self, depend):
701 """Adds dependencies to ignore."""
703 self._add_child(self.ignore, self.ignore_dict, depend)
706 if SCons.Util.is_List(e):
710 raise SCons.Errors.UserError("attempted to ignore a non-Node dependency of %s:\n\t%s is a %s, not a Node" % (str(self), s, type(e)))
712 def add_source(self, source):
715 self._add_child(self.sources, self.sources_dict, source)
718 if SCons.Util.is_List(e):
722 raise SCons.Errors.UserError("attempted to add a non-Node as source of %s:\n\t%s is a %s, not a Node" % (str(self), s, type(e)))
724 def _add_child(self, collection, dict, child):
725 """Adds 'child' to 'collection', first checking 'dict' to see
726 if it's already present."""
727 if type(child) is not type([]):
730 if not isinstance(c, Node):
734 if not dict.has_key(c):
739 self._children_reset()
741 def add_wkid(self, wkid):
742 """Add a node to the list of kids waiting to be evaluated"""
743 if self.wkids != None:
744 self.wkids.append(wkid)
746 def _children_reset(self):
748 # We need to let the Executor clear out any calculated
749 # bsig info that it's cached so we can re-calculate it.
750 self.executor_cleanup()
752 def do_not_ignore(self, node):
753 return node not in self.ignore
755 def _all_children_get(self):
756 # The return list may contain duplicate Nodes, especially in
757 # source trees where there are a lot of repeated #includes
758 # of a tangle of .h files. Profiling shows, however, that
759 # eliminating the duplicates with a brute-force approach that
760 # preserves the order (that is, something like:
767 # takes more cycles than just letting the underlying methods
768 # hand back cached values if a Node's information is requested
769 # multiple times. (Other methods of removing duplicates, like
770 # using dictionary keys, lose the order, and the only ordered
771 # dictionary patterns I found all ended up using "not in"
772 # internally anyway...)
773 if self.implicit is None:
774 return self.sources + self.depends
776 return self.sources + self.depends + self.implicit
778 def _children_get(self):
780 children = self._all_children_get()
782 children = filter(self.do_not_ignore, children)
785 def all_children(self, scan=1):
786 """Return a list of all the node's direct children."""
789 return self._all_children_get()
791 def children(self, scan=1):
792 """Return a list of the node's direct children, minus those
793 that are ignored by this node."""
796 return self._children_get()
798 def set_state(self, state):
804 def current(self, calc=None):
805 """Default check for whether the Node is current: unknown Node
806 subtypes are always out of date, so they will always get built."""
809 def children_are_up_to_date(self, calc=None):
810 """Alternate check for whether the Node is current: If all of
811 our children were up-to-date, then this Node was up-to-date, too.
813 The SCons.Node.Alias and SCons.Node.Python.Value subclasses
814 rebind their current() method to this method."""
815 # Allow the children to calculate their signatures.
816 self.binfo = self.gen_binfo(calc)
817 if self.always_build:
820 for kid in self.children(None):
822 if s and (not state or s > state):
824 return (state == 0 or state == SCons.Node.up_to_date)
826 def is_literal(self):
827 """Always pass the string representation of a Node to
828 the command interpreter literally."""
831 def add_pre_action(self, act):
832 """Adds an Action performed on this Node only before
834 self.pre_actions.append(act)
835 # executor must be recomputed to include new pre-actions
836 self.reset_executor()
838 def add_post_action(self, act):
839 """Adds and Action performed on this Node only after
841 self.post_actions.append(act)
842 # executor must be recomputed to include new pre-actions
843 self.reset_executor()
845 def render_include_tree(self):
847 Return a text representation, suitable for displaying to the
848 user, of the include tree for the sources of this node.
850 if self.is_derived() and self.env:
851 env = self.get_build_env()
852 for s in self.sources:
853 scanner = self.get_source_scanner(s)
854 path = self.get_build_scanner_path(scanner)
855 def f(node, env=env, scanner=scanner, path=path):
856 return node.get_found_includes(env, scanner, path)
857 return SCons.Util.render_tree(s, f, 1)
861 def get_abspath(self):
863 Return an absolute path to the Node. This will return simply
864 str(Node) by default, but for Node types that have a concept of
865 relative path, this might return something different.
869 def for_signature(self):
871 Return a string representation of the Node that will always
872 be the same for this particular Node, no matter what. This
873 is by contrast to the __str__() method, which might, for
874 instance, return a relative path for a file Node. The purpose
875 of this method is to generate a value to be used in signature
876 calculation for the command line used to build a target, and
877 we use this method instead of str() to avoid unnecessary
878 rebuilds. This method does not need to return something that
879 would actually work in a command line; it can return any kind of
880 nonsense, so long as it does not change.
884 def get_string(self, for_signature):
885 """This is a convenience function designed primarily to be
886 used in command generators (i.e., CommandGeneratorActions or
887 Environment variables that are callable), which are called
888 with a for_signature argument that is nonzero if the command
889 generator is being called to generate a signature for the
890 command line, which determines if we should rebuild or not.
892 Such command generators should use this method in preference
893 to str(Node) when converting a Node to a string, passing
894 in the for_signature parameter, such that we will call
895 Node.for_signature() or str(Node) properly, depending on whether
896 we are calculating a signature or actually constructing a
899 return self.for_signature()
902 def get_subst_proxy(self):
904 This method is expected to return an object that will function
905 exactly like this Node, except that it implements any additional
906 special features that we would like to be in effect for
907 Environment variable substitution. The principle use is that
908 some Nodes would like to implement a __getattr__() method,
909 but putting that in the Node type itself has a tendency to kill
910 performance. We instead put it in a proxy and return it from
911 this method. It is legal for this method to return self
912 if no new functionality is needed for Environment substitution.
917 if not self.exists():
918 return "building `%s' because it doesn't exist\n" % self
920 old = self.get_stored_info()
924 def dictify(result, kids, sigs):
925 for k, s in zip(kids, sigs):
930 dictify(osig, old.bsources, old.bsourcesigs)
931 dictify(osig, old.bdepends, old.bdependsigs)
932 dictify(osig, old.bimplicit, old.bimplicitsigs)
933 except AttributeError:
934 return "Cannot explain why `%s' is being rebuilt: No previous build information found\n" % self
939 dictify(nsig, new.bsources, new.bsourcesigs)
940 dictify(nsig, new.bdepends, new.bdependsigs)
941 dictify(nsig, new.bimplicit, new.bimplicitsigs)
943 old_bkids = old.bsources + old.bdepends + old.bimplicit
944 new_bkids = new.bsources + new.bdepends + new.bimplicit
946 # The sources and dependencies we'll want to report are all stored
947 # as relative paths to this target's directory, but we want to
948 # report them relative to the top-level SConstruct directory,
949 # so we only print them after running them through this lambda
950 # to turn them into the right relative Node and then return
952 stringify = lambda s, E=self.dir.Entry: str(E(s))
956 removed = filter(lambda x, nk=new_bkids: not x in nk, old_bkids)
958 removed = map(stringify, removed)
959 fmt = "`%s' is no longer a dependency\n"
960 lines.extend(map(lambda s, fmt=fmt: fmt % s, removed))
963 if not k in old_bkids:
964 lines.append("`%s' is a new dependency\n" % stringify(k))
965 elif osig[k] != nsig[k]:
966 lines.append("`%s' changed\n" % stringify(k))
968 if len(lines) == 0 and old_bkids != new_bkids:
969 lines.append("the dependency order changed:\n" +
970 "%sold: %s\n" % (' '*15, map(stringify, old_bkids)) +
971 "%snew: %s\n" % (' '*15, map(stringify, new_bkids)))
974 def fmt_with_title(title, strlines):
975 lines = string.split(strlines, '\n')
976 sep = '\n' + ' '*(15 + len(title))
977 return ' '*15 + title + string.join(lines, sep) + '\n'
978 if old.bactsig != new.bactsig:
979 if old.bact == new.bact:
980 lines.append("the contents of the build action changed\n" +
981 fmt_with_title('action: ', new.bact))
983 lines.append("the build action changed:\n" +
984 fmt_with_title('old: ', old.bact) +
985 fmt_with_title('new: ', new.bact))
988 return "rebuilding `%s' for unknown reasons\n" % self
990 preamble = "rebuilding `%s' because" % self
992 return "%s %s" % (preamble, lines[0])
994 lines = ["%s:\n" % preamble] + lines
995 return string.join(lines, ' '*11)
998 ul = UserList.UserList([2])
1005 class NodeList(UserList.UserList):
1007 return str(map(str, self.data))
1011 if not SCons.Memoize.has_metaclass:
1013 class Node(SCons.Memoize.Memoizer, _Base):
1014 def __init__(self, *args, **kw):
1015 apply(_Base.__init__, (self,)+args, kw)
1016 SCons.Memoize.Memoizer.__init__(self)
1019 def get_children(node, parent): return node.children()
1020 def ignore_cycle(node, stack): pass
1021 def do_nothing(node, parent): pass
1024 """An iterator for walking a Node tree.
1026 This is depth-first, children are visited before the parent.
1027 The Walker object can be initialized with any node, and
1028 returns the next node on the descent with each next() call.
1029 'kids_func' is an optional function that will be called to
1030 get the children of a node instead of calling 'children'.
1031 'cycle_func' is an optional function that will be called
1032 when a cycle is detected.
1034 This class does not get caught in node cycles caused, for example,
1035 by C header file include loops.
1037 def __init__(self, node, kids_func=get_children,
1038 cycle_func=ignore_cycle,
1039 eval_func=do_nothing):
1040 self.kids_func = kids_func
1041 self.cycle_func = cycle_func
1042 self.eval_func = eval_func
1043 node.wkids = copy.copy(kids_func(node, None))
1045 self.history = {} # used to efficiently detect and avoid cycles
1046 self.history[node] = None
1049 """Return the next node for this walk of the tree.
1051 This function is intentionally iterative, not recursive,
1052 to sidestep any issues of stack size limitations.
1056 if self.stack[-1].wkids:
1057 node = self.stack[-1].wkids.pop(0)
1058 if not self.stack[-1].wkids:
1059 self.stack[-1].wkids = None
1060 if self.history.has_key(node):
1061 self.cycle_func(node, self.stack)
1063 node.wkids = copy.copy(self.kids_func(node, self.stack[-1]))
1064 self.stack.append(node)
1065 self.history[node] = None
1067 node = self.stack.pop()
1068 del self.history[node]
1071 parent = self.stack[-1]
1074 self.eval_func(node, parent)
1079 return not self.stack
1082 arg2nodes_lookups = []