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__"
52 from SCons.Debug import logInstanceCreation
58 # These are in "priority" order, so that the maximum value for any
59 # child/dependency of a node represents the state of that node if
60 # it has no builder of its own. The canonical example is a file
61 # system directory, which is only up to date if all of its children
68 stack = 6 # nodes that are in the current Taskmaster execution stack
70 # controls whether implicit depedencies are cached:
73 # controls whether implicit dep changes are ignored:
74 implicit_deps_unchanged = 0
76 # controls whether the cached implicit deps are ignored:
77 implicit_deps_changed = 0
79 # A variable that can be set to an interface-specific function be called
80 # to annotate a Node with information about its creation.
81 def do_nothing(node): pass
86 def __cmp__(self, other):
87 return cmp(self.__dict__, other.__dict__)
90 """The base Node class, for entities that we know how to
91 build, or use to build other Nodes.
98 if __debug__: logInstanceCreation(self, 'Node')
99 # Note that we no longer explicitly initialize a self.builder
100 # attribute to None here. That's because the self.builder
101 # attribute may be created on-the-fly later by a subclass (the
102 # canonical example being a builder to fetch a file from a
103 # source code system like CVS or Subversion).
105 # Each list of children that we maintain is accompanied by a
106 # dictionary used to look up quickly whether a node is already
107 # present in the list. Empirical tests showed that it was
108 # fastest to maintain them as side-by-side Node attributes in
109 # this way, instead of wrapping up each list+dictionary pair in
110 # a class. (Of course, we could always still do that in the
111 # future if we had a good reason to...).
112 self.sources = [] # source files used to build node
113 self.sources_dict = {}
114 self.depends = [] # explicit dependencies (from Depends)
115 self.depends_dict = {}
116 self.ignore = [] # dependencies to ignore
117 self.ignore_dict = {}
118 self.implicit = None # implicit (scanned) dependencies (None means not scanned yet)
119 self.waiting_parents = []
120 self.wkids = None # Kids yet to walk, when it's an array
121 self.target_scanner = None # explicit scanner from this node's Builder
122 self.source_scanner = None
123 self.backup_source_scanner = None
128 self.always_build = None
129 self.found_includes = {}
131 self.overrides = {} # construction variable overrides for building this node
132 self.attributes = self.Attrs() # Generic place to stick information about the Node.
133 self.side_effect = 0 # true iff this node is a side effect
134 self.side_effects = [] # the side effects of building this target
135 self.pre_actions = []
136 self.post_actions = []
137 self.linked = 0 # is this node linked to the build directory?
139 # Let the interface in which the build engine is embedded
140 # annotate this Node with its own info (like a description of
141 # what line in what file created the node, for example).
144 def get_suffix(self):
147 def generate_build_dict(self):
148 """Return an appropriate dictionary of values for building
152 def get_build_env(self):
153 """Fetch the appropriate Environment to build this node."""
154 executor = self.get_executor()
155 return executor.get_build_env()
157 def set_executor(self, executor):
158 """Set the action executor for this node."""
159 self.executor = executor
161 def get_executor(self, create=1):
162 """Fetch the action executor for this node. Create one if
163 there isn't already one, and requested to do so."""
165 executor = self.executor
166 except AttributeError:
169 import SCons.Executor
170 executor = SCons.Executor.Executor(self.builder.action,
172 [self.builder.overrides],
175 self.executor = executor
178 def retrieve_from_cache(self):
179 """Try to retrieve the node's content from a cache
181 This method is called from multiple threads in a parallel build,
182 so only do thread safe stuff here. Do thread unsafe stuff in
185 Returns true iff the node was successfully retrieved.
189 def build(self, **kw):
190 """Actually build the node.
192 This method is called from multiple threads in a parallel build,
193 so only do thread safe stuff here. Do thread unsafe stuff in
196 if not self.has_builder():
198 def errfunc(stat, node=self):
199 raise SCons.Errors.BuildError(node=node, errstr="Error %d" % stat)
200 executor = self.get_executor()
201 apply(executor, (self, errfunc), kw)
204 """Called just after this node is sucessfully built."""
206 new_binfo = self.binfo
207 except AttributeError:
210 self.store_info(new_binfo)
212 # Clear our scanned included files.
213 self.found_includes = {}
216 # Clear the implicit dependency caches of any Nodes
217 # waiting for this Node to be built.
218 for parent in self.waiting_parents:
219 parent.implicit = None
221 self.waiting_parents = []
223 # The content just changed, delete any cached info
224 # so it will get recalculated.
227 def add_to_waiting_parents(self, node):
228 self.waiting_parents.append(node)
230 def call_for_all_waiting_parents(self, func):
232 for parent in self.waiting_parents:
233 parent.call_for_all_waiting_parents(func)
235 def postprocess(self):
236 """Clean up anything we don't need to hang onto after we've
239 executor = self.get_executor(create=None)
240 except AttributeError:
246 """Completely clear a Node of all its cached state (so that it
247 can be re-evaluated by interfaces that do continuous integration
254 delattr(self, '_calculated_sig')
255 except AttributeError:
258 self.found_includes = {}
261 self.waiting_parents = []
264 """Called just after this node has been visited
265 without requiring a build.."""
268 def depends_on(self, nodes):
269 """Does this node depend on any of 'nodes'?"""
271 if node in self.children():
276 def builder_set(self, builder):
277 self.builder = builder
279 def has_builder(self):
280 """Return whether this Node has a builder or not.
282 In Boolean tests, this turns out to be a *lot* more efficient
283 than simply examining the builder attribute directly ("if
284 node.builder: ..."). When the builder attribute is examined
285 directly, it ends up calling __getattr__ for both the __len__
286 and __nonzero__ attributes on instances of our Builder Proxy
287 class(es), generating a bazillion extra calls and slowing
288 things down immensely.
292 except AttributeError:
293 # There was no explicit builder for this Node, so initialize
294 # the self.builder attribute to None now.
299 def is_derived(self):
301 Returns true iff this node is derived (i.e. built).
303 This should return true only for nodes whose path should be in
304 the build directory when duplicate=0 and should contribute their build
305 signatures when they are used as source files to other derived files. For
306 example: source with source builders are not derived in this sense,
307 and hence should not return true.
309 return self.has_builder() or self.side_effect
311 def is_pseudo_derived(self):
313 Returns true iff this node is built, but should use a source path
314 when duplicate=0 and should contribute a content signature (i.e.
315 source signature) when used as a source for other derived files.
319 def alter_targets(self):
320 """Return a list of alternate targets for this Node.
324 def get_found_includes(self, env, scanner, target):
325 """Return the scanned include lines (implicit dependencies)
328 The default is no implicit dependencies. We expect this method
329 to be overridden by any subclass that can be scanned for
330 implicit dependencies.
334 def get_implicit_deps(self, env, scanner, target):
335 """Return a list of implicit dependencies for this node.
337 This method exists to handle recursive invocation of the scanner
338 on the implicit dependencies returned by the scanner, if the
339 scanner's recursive flag says that we should.
344 # Give the scanner a chance to select a more specific scanner
346 scanner = scanner.select(self)
349 recurse = scanner.recursive
350 except AttributeError:
359 d = filter(lambda x, seen=seen: not seen.has_key(x),
360 n.get_found_includes(env, scanner, target))
370 # cache used to make implicit_factory fast.
371 implicit_factory_cache = {}
373 def implicit_factory(self, path):
375 Turn a cache implicit dependency path into a node.
376 This is called so many times that doing caching
377 here is a significant perforamnce boost.
380 return self.implicit_factory_cache[path]
382 n = self.builder.source_factory(path)
383 self.implicit_factory_cache[path] = n
386 def get_source_scanner(self, node):
387 """Fetch the source scanner for the specified node
389 NOTE: "self" is the target being built, "node" is
390 the source file for which we want to fetch the scanner.
392 if self.source_scanner:
393 return self.source_scanner
395 scanner = node.builder.source_scanner
398 except AttributeError:
400 return node.backup_source_scanner or None
403 """Scan this node's dependents for implicit dependencies."""
404 # Don't bother scanning non-derived files, because we don't
405 # care what their dependencies are.
406 # Don't scan again, if we already have scanned.
407 if not self.implicit is None:
410 self.implicit_dict = {}
411 self._children_reset()
412 if not self.has_builder():
415 build_env = self.get_build_env()
417 # XXX Here's where we implement --implicit-cache. This doesn't
418 # do anything right now, but we're probably going to re-implement
419 # as a way to cache #include lines from source files, so I want
420 # to keep this code around for now.
422 #if implicit_cache and not implicit_deps_changed:
423 # implicit = self.get_stored_implicit()
424 # if implicit is not None:
425 # implicit = map(self.implicit_factory, implicit)
426 # self._add_child(self.implicit, self.implicit_dict, implicit)
427 # calc = build_env.get_calculator()
428 # if implicit_deps_unchanged or calc.current(self, calc.bsig(self)):
431 # # one of this node's sources has changed, so
432 # # we need to recalculate the implicit deps,
435 # self.implicit_dict = {}
436 # self._children_reset()
439 for child in self.children(scan=0):
440 scanner = self.get_source_scanner(child)
442 deps = child.get_implicit_deps(build_env, scanner, self)
443 self._add_child(self.implicit, self.implicit_dict, deps)
445 # scan this node itself for implicit dependencies
446 deps = self.get_implicit_deps(build_env, self.target_scanner, self)
447 self._add_child(self.implicit, self.implicit_dict, deps)
449 # XXX See note above re: --implicit-cache.
451 # self.store_implicit()
453 def scanner_key(self):
456 def env_set(self, env, safe=0):
457 if safe and self.env:
461 def calculator(self):
462 import SCons.Defaults
464 env = self.env or SCons.Defaults.DefaultEnvironment()
465 return env.get_calculator()
467 def calc_signature(self, calc=None):
469 Select and calculate the appropriate build signature for a node.
472 calc - the signature calculation module
473 returns - the signature
476 return self._calculated_sig
477 except AttributeError:
478 if self.is_derived():
479 import SCons.Defaults
481 env = self.env or SCons.Defaults.DefaultEnvironment()
482 if env.use_build_signature():
483 sig = self.calc_bsig(calc)
485 sig = self.calc_csig(calc)
486 elif not self.rexists():
489 sig = self.calc_csig(calc)
490 self._calculated_sig = sig
497 """Delete the bsig from this node."""
499 delattr(self, 'binfo')
500 except AttributeError:
503 def calc_bsig(self, calc=None):
505 return self.binfo.bsig
506 except AttributeError:
507 self.binfo = self.gen_binfo(calc)
508 return self.binfo.bsig
510 def gen_binfo(self, calc=None):
512 Generate a node's build signature, the digested signatures
513 of its dependency files and build information.
515 node - the node whose sources will be collected
516 cache - alternate node to use for the signature cache
517 returns - the build signature
519 This no longer handles the recursive descent of the
520 node's children's signatures. We expect that they're
521 already built and updated by someone else, if that's
526 calc = self.calculator()
528 binfo = self.new_binfo()
532 sources = self.filter_ignore(self.sources)
533 depends = self.filter_ignore(self.depends)
534 if self.implicit is None:
537 implicit = self.filter_ignore(self.implicit)
539 def calc_signature(node, calc=calc):
540 return node.calc_signature(calc)
541 sourcesigs = map(calc_signature, sources)
542 dependsigs = map(calc_signature, depends)
543 implicitsigs = map(calc_signature, implicit)
545 binfo.bsources = map(str, sources)
546 binfo.bdepends = map(str, depends)
547 binfo.bimplicit = map(str, implicit)
549 binfo.bsourcesigs = sourcesigs
550 binfo.bdependsigs = dependsigs
551 binfo.bimplicitsigs = implicitsigs
553 sigs = sourcesigs + dependsigs + implicitsigs
555 if self.has_builder():
556 executor = self.get_executor()
557 binfo.bact = str(executor)
558 binfo.bactsig = calc.module.signature(executor)
559 sigs.append(binfo.bactsig)
561 binfo.bsig = calc.module.collect(filter(None, sigs))
568 except AttributeError:
571 def calc_csig(self, calc=None):
574 except AttributeError:
575 binfo = self.binfo = self.new_binfo()
578 except AttributeError:
580 calc = self.calculator()
581 binfo.csig = calc.module.signature(self)
582 self.store_info(binfo)
585 def store_info(self, obj):
586 """Make the build signature permanent (that is, store it in the
587 .sconsign file or equivalent)."""
590 def get_stored_info(self):
593 def get_stored_implicit(self):
594 """Fetch the stored implicit dependencies"""
597 def set_precious(self, precious = 1):
598 """Set the Node's precious value."""
599 self.precious = precious
601 def set_always_build(self, always_build = 1):
602 """Set the Node's always_build value."""
603 self.always_build = always_build
606 """Does this node exists?"""
607 # All node exist by default:
611 """Does this node exist locally or in a repositiory?"""
612 # There are no repositories by default:
616 """Prepare for this Node to be created.
617 The default implemenation checks that all children either exist
621 return not node.is_derived() and \
622 not node.is_pseudo_derived() and \
623 not node.linked and \
625 missing_sources = filter(missing, self.children())
627 desc = "Source `%s' not found, needed by target `%s'." % (missing_sources[0], self)
628 raise SCons.Errors.StopError, desc
631 """Remove this Node: no-op by default."""
634 def add_dependency(self, depend):
635 """Adds dependencies."""
637 self._add_child(self.depends, self.depends_dict, depend)
640 if SCons.Util.is_List(e):
644 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)))
646 def add_ignore(self, depend):
647 """Adds dependencies to ignore."""
649 self._add_child(self.ignore, self.ignore_dict, depend)
652 if SCons.Util.is_List(e):
656 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)))
658 def add_source(self, source):
661 self._add_child(self.sources, self.sources_dict, source)
664 if SCons.Util.is_List(e):
668 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)))
670 def _add_child(self, collection, dict, child):
671 """Adds 'child' to 'collection', first checking 'dict' to see
672 if it's already present."""
673 if type(child) is not type([]):
676 if not isinstance(c, Node):
680 if not dict.has_key(c):
685 self._children_reset()
687 def add_wkid(self, wkid):
688 """Add a node to the list of kids waiting to be evaluated"""
689 if self.wkids != None:
690 self.wkids.append(wkid)
692 def _children_reset(self):
694 delattr(self, '_children')
695 except AttributeError:
698 def filter_ignore(self, nodelist):
701 for node in nodelist:
702 if node not in ignore:
706 def children(self, scan=1):
707 """Return a list of the node's direct children, minus those
708 that are ignored by this node."""
712 return self._children
713 except AttributeError:
714 c = self.all_children(scan=0)
715 self._children = self.filter_ignore(c)
716 return self._children
718 def all_children(self, scan=1):
719 """Return a list of all the node's direct children."""
720 # The return list may contain duplicate Nodes, especially in
721 # source trees where there are a lot of repeated #includes
722 # of a tangle of .h files. Profiling shows, however, that
723 # eliminating the duplicates with a brute-force approach that
724 # preserves the order (that is, something like:
731 # takes more cycles than just letting the underlying methods
732 # hand back cached values if a Node's information is requested
733 # multiple times. (Other methods of removing duplicates, like
734 # using dictionary keys, lose the order, and the only ordered
735 # dictionary patterns I found all ended up using "not in"
736 # internally anyway...)
739 if self.implicit is None:
740 return self.sources + self.depends
742 return self.sources + self.depends + self.implicit
744 def set_state(self, state):
750 def current(self, calc=None):
751 """Default check for whether the Node is current: unknown Node
752 subtypes are always out of date, so they will always get built."""
755 def children_are_up_to_date(self, calc=None):
756 """Alternate check for whether the Node is current: If all of
757 our children were up-to-date, then this Node was up-to-date, too.
759 The SCons.Node.Alias and SCons.Node.Python.Value subclasses
760 rebind their current() method to this method."""
761 # Allow the children to calculate their signatures.
762 self.binfo = self.gen_binfo(calc)
764 for kid in self.children(None):
766 if s and (not state or s > state):
768 return (state == 0 or state == SCons.Node.up_to_date)
770 def is_literal(self):
771 """Always pass the string representation of a Node to
772 the command interpreter literally."""
775 def add_pre_action(self, act):
776 """Adds an Action performed on this Node only before
778 self.pre_actions.append(act)
780 def add_post_action(self, act):
781 """Adds and Action performed on this Node only after
783 self.post_actions.append(act)
785 def render_include_tree(self):
787 Return a text representation, suitable for displaying to the
788 user, of the include tree for the sources of this node.
790 if self.is_derived() and self.env:
791 env = self.get_build_env()
792 for s in self.sources:
793 scanner = s.get_source_scanner(self)
794 def f(node, env=env, scanner=scanner, target=self):
795 return node.get_found_includes(env, scanner, target)
796 return SCons.Util.render_tree(s, f, 1)
800 def get_abspath(self):
802 Return an absolute path to the Node. This will return simply
803 str(Node) by default, but for Node types that have a concept of
804 relative path, this might return something different.
808 def for_signature(self):
810 Return a string representation of the Node that will always
811 be the same for this particular Node, no matter what. This
812 is by contrast to the __str__() method, which might, for
813 instance, return a relative path for a file Node. The purpose
814 of this method is to generate a value to be used in signature
815 calculation for the command line used to build a target, and
816 we use this method instead of str() to avoid unnecessary
817 rebuilds. This method does not need to return something that
818 would actually work in a command line; it can return any kind of
819 nonsense, so long as it does not change.
823 def get_string(self, for_signature):
824 """This is a convenience function designed primarily to be
825 used in command generators (i.e., CommandGeneratorActions or
826 Environment variables that are callable), which are called
827 with a for_signature argument that is nonzero if the command
828 generator is being called to generate a signature for the
829 command line, which determines if we should rebuild or not.
831 Such command generators shoud use this method in preference
832 to str(Node) when converting a Node to a string, passing
833 in the for_signature parameter, such that we will call
834 Node.for_signature() or str(Node) properly, depending on whether
835 we are calculating a signature or actually constructing a
838 return self.for_signature()
841 def get_subst_proxy(self):
843 This method is expected to return an object that will function
844 exactly like this Node, except that it implements any additional
845 special features that we would like to be in effect for
846 Environment variable substitution. The principle use is that
847 some Nodes would like to implement a __getattr__() method,
848 but putting that in the Node type itself has a tendency to kill
849 performance. We instead put it in a proxy and return it from
850 this method. It is legal for this method to return self
851 if no new functionality is needed for Environment substitution.
856 if not self.exists():
857 return "building `%s' because it doesn't exist\n" % self
859 old = self.get_stored_info()
863 def dictify(result, kids, sigs):
864 for k, s in zip(kids, sigs):
868 old_bkids = old.bsources + old.bdepends + old.bimplicit
869 except AttributeError:
870 return "Cannot explain why `%s' is being rebuilt: No previous build information found\n" % self
873 dictify(osig, old.bsources, old.bsourcesigs)
874 dictify(osig, old.bdepends, old.bdependsigs)
875 dictify(osig, old.bimplicit, old.bimplicitsigs)
877 new_bsources = map(str, self.binfo.bsources)
878 new_bdepends = map(str, self.binfo.bdepends)
879 new_bimplicit = map(str, self.binfo.bimplicit)
882 dictify(nsig, new_bsources, self.binfo.bsourcesigs)
883 dictify(nsig, new_bdepends, self.binfo.bdependsigs)
884 dictify(nsig, new_bimplicit, self.binfo.bimplicitsigs)
886 new_bkids = new_bsources + new_bdepends + new_bimplicit
887 lines = map(lambda x: "`%s' is no longer a dependency\n" % x,
888 filter(lambda x, nk=new_bkids: not x in nk, old_bkids))
891 if not k in old_bkids:
892 lines.append("`%s' is a new dependency\n" % k)
893 elif osig[k] != nsig[k]:
894 lines.append("`%s' changed\n" % k)
897 newact, newactsig = self.binfo.bact, self.binfo.bactsig
898 if old.bact != newact:
899 lines.append("the build action changed:\n" +
900 "%sold: %s\n" % (' '*15, old.bact) +
901 "%snew: %s\n" % (' '*15, newact))
904 lines.append("the dependency order changed:\n" +
905 "%sold: %s\n" % (' '*15, old_bkids) +
906 "%snew: %s\n" % (' '*15, new_bkids))
908 preamble = "rebuilding `%s' because" % self
910 return "%s %s" % (preamble, lines[0])
912 lines = ["%s:\n" % preamble] + lines
913 return string.join(lines, ' '*11)
915 def get_children(node, parent): return node.children()
916 def ignore_cycle(node, stack): pass
917 def do_nothing(node, parent): pass
920 """An iterator for walking a Node tree.
922 This is depth-first, children are visited before the parent.
923 The Walker object can be initialized with any node, and
924 returns the next node on the descent with each next() call.
925 'kids_func' is an optional function that will be called to
926 get the children of a node instead of calling 'children'.
927 'cycle_func' is an optional function that will be called
928 when a cycle is detected.
930 This class does not get caught in node cycles caused, for example,
931 by C header file include loops.
933 def __init__(self, node, kids_func=get_children,
934 cycle_func=ignore_cycle,
935 eval_func=do_nothing):
936 self.kids_func = kids_func
937 self.cycle_func = cycle_func
938 self.eval_func = eval_func
939 node.wkids = copy.copy(kids_func(node, None))
941 self.history = {} # used to efficiently detect and avoid cycles
942 self.history[node] = None
945 """Return the next node for this walk of the tree.
947 This function is intentionally iterative, not recursive,
948 to sidestep any issues of stack size limitations.
952 if self.stack[-1].wkids:
953 node = self.stack[-1].wkids.pop(0)
954 if not self.stack[-1].wkids:
955 self.stack[-1].wkids = None
956 if self.history.has_key(node):
957 self.cycle_func(node, self.stack)
959 node.wkids = copy.copy(self.kids_func(node, self.stack[-1]))
960 self.stack.append(node)
961 self.history[node] = None
963 node = self.stack.pop()
964 del self.history[node]
967 parent = self.stack[-1]
970 self.eval_func(node, parent)
975 return not self.stack
978 arg2nodes_lookups = []