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 multiple_side_effect_has_builder = has_builder
301 def is_derived(self):
303 Returns true iff this node is derived (i.e. built).
305 This should return true only for nodes whose path should be in
306 the build directory when duplicate=0 and should contribute their build
307 signatures when they are used as source files to other derived files. For
308 example: source with source builders are not derived in this sense,
309 and hence should not return true.
311 return self.has_builder() or self.side_effect
313 def is_pseudo_derived(self):
315 Returns true iff this node is built, but should use a source path
316 when duplicate=0 and should contribute a content signature (i.e.
317 source signature) when used as a source for other derived files.
321 def alter_targets(self):
322 """Return a list of alternate targets for this Node.
326 def get_found_includes(self, env, scanner, target):
327 """Return the scanned include lines (implicit dependencies)
330 The default is no implicit dependencies. We expect this method
331 to be overridden by any subclass that can be scanned for
332 implicit dependencies.
336 def get_implicit_deps(self, env, scanner, target):
337 """Return a list of implicit dependencies for this node.
339 This method exists to handle recursive invocation of the scanner
340 on the implicit dependencies returned by the scanner, if the
341 scanner's recursive flag says that we should.
346 # Give the scanner a chance to select a more specific scanner
348 scanner = scanner.select(self)
351 recurse = scanner.recursive
352 except AttributeError:
361 d = filter(lambda x, seen=seen: not seen.has_key(x),
362 n.get_found_includes(env, scanner, target))
372 # cache used to make implicit_factory fast.
373 implicit_factory_cache = {}
375 def implicit_factory(self, path):
377 Turn a cache implicit dependency path into a node.
378 This is called so many times that doing caching
379 here is a significant perforamnce boost.
382 return self.implicit_factory_cache[path]
384 n = self.builder.source_factory(path)
385 self.implicit_factory_cache[path] = n
388 def get_source_scanner(self, node):
389 """Fetch the source scanner for the specified node
391 NOTE: "self" is the target being built, "node" is
392 the source file for which we want to fetch the scanner.
394 if self.source_scanner:
395 return self.source_scanner
397 scanner = node.builder.source_scanner
400 except AttributeError:
402 return node.backup_source_scanner or None
405 """Scan this node's dependents for implicit dependencies."""
406 # Don't bother scanning non-derived files, because we don't
407 # care what their dependencies are.
408 # Don't scan again, if we already have scanned.
409 if not self.implicit is None:
412 self.implicit_dict = {}
413 self._children_reset()
414 if not self.has_builder():
417 build_env = self.get_build_env()
419 # Here's where we implement --implicit-cache.
420 if implicit_cache and not implicit_deps_changed:
421 implicit = self.get_stored_implicit()
422 if implicit is not None:
423 implicit = map(self.implicit_factory, implicit)
424 self._add_child(self.implicit, self.implicit_dict, implicit)
425 calc = build_env.get_calculator()
426 if implicit_deps_unchanged or self.current(calc, scan=0):
429 # one of this node's sources has changed, so
430 # we need to recalculate the implicit deps,
433 self.implicit_dict = {}
434 self._children_reset()
437 for child in self.children(scan=0):
438 scanner = self.get_source_scanner(child)
440 deps = child.get_implicit_deps(build_env, scanner, self)
441 self._add_child(self.implicit, self.implicit_dict, deps)
443 # scan this node itself for implicit dependencies
444 deps = self.get_implicit_deps(build_env, self.target_scanner, self)
445 self._add_child(self.implicit, self.implicit_dict, deps)
447 # XXX See note above re: --implicit-cache.
449 # self.store_implicit()
451 def scanner_key(self):
454 def env_set(self, env, safe=0):
455 if safe and self.env:
459 def calculator(self):
460 import SCons.Defaults
462 env = self.env or SCons.Defaults.DefaultEnvironment()
463 return env.get_calculator()
465 def calc_signature(self, calc=None):
467 Select and calculate the appropriate build signature for a node.
470 calc - the signature calculation module
471 returns - the signature
474 return self._calculated_sig
475 except AttributeError:
476 if self.is_derived():
477 import SCons.Defaults
479 env = self.env or SCons.Defaults.DefaultEnvironment()
480 if env.use_build_signature():
481 sig = self.calc_bsig(calc)
483 sig = self.calc_csig(calc)
484 elif not self.rexists():
487 sig = self.calc_csig(calc)
488 self._calculated_sig = sig
495 """Delete the bsig from this node."""
497 delattr(self, 'binfo')
498 except AttributeError:
501 def calc_bsig(self, calc=None):
503 return self.binfo.bsig
504 except AttributeError:
505 self.binfo = self.gen_binfo(calc)
506 return self.binfo.bsig
508 def gen_binfo(self, calc=None, scan=1):
510 Generate a node's build signature, the digested signatures
511 of its dependency files and build information.
513 node - the node whose sources will be collected
514 cache - alternate node to use for the signature cache
515 returns - the build signature
517 This no longer handles the recursive descent of the
518 node's children's signatures. We expect that they're
519 already built and updated by someone else, if that's
524 calc = self.calculator()
526 binfo = self.new_binfo()
531 sources = self.filter_ignore(self.sources)
532 depends = self.filter_ignore(self.depends)
533 if self.implicit is None:
536 implicit = self.filter_ignore(self.implicit)
538 def calc_signature(node, calc=calc):
539 return node.calc_signature(calc)
540 sourcesigs = map(calc_signature, sources)
541 dependsigs = map(calc_signature, depends)
542 implicitsigs = map(calc_signature, implicit)
544 sigs = sourcesigs + dependsigs + implicitsigs
546 if self.has_builder():
547 executor = self.get_executor()
548 binfo.bact = executor.get_contents()
549 binfo.bactsig = calc.module.signature(executor)
550 sigs.append(binfo.bactsig)
552 binfo.bsources = map(str, sources)
553 binfo.bdepends = map(str, depends)
554 binfo.bimplicit = map(str, implicit)
556 binfo.bsourcesigs = sourcesigs
557 binfo.bdependsigs = dependsigs
558 binfo.bimplicitsigs = implicitsigs
560 binfo.bsig = calc.module.collect(filter(None, sigs))
567 except AttributeError:
570 def calc_csig(self, calc=None):
573 except AttributeError:
574 binfo = self.binfo = self.new_binfo()
577 except AttributeError:
579 calc = self.calculator()
580 binfo.csig = calc.module.signature(self)
581 self.store_info(binfo)
584 def store_info(self, obj):
585 """Make the build signature permanent (that is, store it in the
586 .sconsign file or equivalent)."""
589 def get_stored_info(self):
592 def get_stored_implicit(self):
593 """Fetch the stored implicit dependencies"""
596 def set_precious(self, precious = 1):
597 """Set the Node's precious value."""
598 self.precious = precious
600 def set_always_build(self, always_build = 1):
601 """Set the Node's always_build value."""
602 self.always_build = always_build
605 """Does this node exists?"""
606 # All node exist by default:
610 """Does this node exist locally or in a repositiory?"""
611 # There are no repositories by default:
615 """Prepare for this Node to be created.
616 The default implemenation checks that all children either exist
620 return not node.is_derived() and \
621 not node.is_pseudo_derived() and \
622 not node.linked and \
624 missing_sources = filter(missing, self.children())
626 desc = "Source `%s' not found, needed by target `%s'." % (missing_sources[0], self)
627 raise SCons.Errors.StopError, desc
630 """Remove this Node: no-op by default."""
633 def add_dependency(self, depend):
634 """Adds dependencies."""
636 self._add_child(self.depends, self.depends_dict, depend)
639 if SCons.Util.is_List(e):
643 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)))
645 def add_ignore(self, depend):
646 """Adds dependencies to ignore."""
648 self._add_child(self.ignore, self.ignore_dict, depend)
651 if SCons.Util.is_List(e):
655 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)))
657 def add_source(self, source):
660 self._add_child(self.sources, self.sources_dict, source)
663 if SCons.Util.is_List(e):
667 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)))
669 def _add_child(self, collection, dict, child):
670 """Adds 'child' to 'collection', first checking 'dict' to see
671 if it's already present."""
672 if type(child) is not type([]):
675 if not isinstance(c, Node):
679 if not dict.has_key(c):
684 self._children_reset()
686 def add_wkid(self, wkid):
687 """Add a node to the list of kids waiting to be evaluated"""
688 if self.wkids != None:
689 self.wkids.append(wkid)
691 def _children_reset(self):
693 delattr(self, '_children')
694 except AttributeError:
697 def filter_ignore(self, nodelist):
700 for node in nodelist:
701 if node not in ignore:
705 def children(self, scan=1):
706 """Return a list of the node's direct children, minus those
707 that are ignored by this node."""
711 return self._children
712 except AttributeError:
713 c = self.all_children(scan=0)
714 self._children = self.filter_ignore(c)
715 return self._children
717 def all_children(self, scan=1):
718 """Return a list of all the node's direct children."""
719 # The return list may contain duplicate Nodes, especially in
720 # source trees where there are a lot of repeated #includes
721 # of a tangle of .h files. Profiling shows, however, that
722 # eliminating the duplicates with a brute-force approach that
723 # preserves the order (that is, something like:
730 # takes more cycles than just letting the underlying methods
731 # hand back cached values if a Node's information is requested
732 # multiple times. (Other methods of removing duplicates, like
733 # using dictionary keys, lose the order, and the only ordered
734 # dictionary patterns I found all ended up using "not in"
735 # internally anyway...)
738 if self.implicit is None:
739 return self.sources + self.depends
741 return self.sources + self.depends + self.implicit
743 def set_state(self, state):
749 def current(self, calc=None):
750 """Default check for whether the Node is current: unknown Node
751 subtypes are always out of date, so they will always get built."""
754 def children_are_up_to_date(self, calc=None):
755 """Alternate check for whether the Node is current: If all of
756 our children were up-to-date, then this Node was up-to-date, too.
758 The SCons.Node.Alias and SCons.Node.Python.Value subclasses
759 rebind their current() method to this method."""
760 # Allow the children to calculate their signatures.
761 self.binfo = self.gen_binfo(calc)
763 for kid in self.children(None):
765 if s and (not state or s > state):
767 return (state == 0 or state == SCons.Node.up_to_date)
769 def is_literal(self):
770 """Always pass the string representation of a Node to
771 the command interpreter literally."""
774 def add_pre_action(self, act):
775 """Adds an Action performed on this Node only before
777 self.pre_actions.append(act)
779 def add_post_action(self, act):
780 """Adds and Action performed on this Node only after
782 self.post_actions.append(act)
784 def render_include_tree(self):
786 Return a text representation, suitable for displaying to the
787 user, of the include tree for the sources of this node.
789 if self.is_derived() and self.env:
790 env = self.get_build_env()
791 for s in self.sources:
792 scanner = s.get_source_scanner(self)
793 def f(node, env=env, scanner=scanner, target=self):
794 return node.get_found_includes(env, scanner, target)
795 return SCons.Util.render_tree(s, f, 1)
799 def get_abspath(self):
801 Return an absolute path to the Node. This will return simply
802 str(Node) by default, but for Node types that have a concept of
803 relative path, this might return something different.
807 def for_signature(self):
809 Return a string representation of the Node that will always
810 be the same for this particular Node, no matter what. This
811 is by contrast to the __str__() method, which might, for
812 instance, return a relative path for a file Node. The purpose
813 of this method is to generate a value to be used in signature
814 calculation for the command line used to build a target, and
815 we use this method instead of str() to avoid unnecessary
816 rebuilds. This method does not need to return something that
817 would actually work in a command line; it can return any kind of
818 nonsense, so long as it does not change.
822 def get_string(self, for_signature):
823 """This is a convenience function designed primarily to be
824 used in command generators (i.e., CommandGeneratorActions or
825 Environment variables that are callable), which are called
826 with a for_signature argument that is nonzero if the command
827 generator is being called to generate a signature for the
828 command line, which determines if we should rebuild or not.
830 Such command generators shoud use this method in preference
831 to str(Node) when converting a Node to a string, passing
832 in the for_signature parameter, such that we will call
833 Node.for_signature() or str(Node) properly, depending on whether
834 we are calculating a signature or actually constructing a
837 return self.for_signature()
840 def get_subst_proxy(self):
842 This method is expected to return an object that will function
843 exactly like this Node, except that it implements any additional
844 special features that we would like to be in effect for
845 Environment variable substitution. The principle use is that
846 some Nodes would like to implement a __getattr__() method,
847 but putting that in the Node type itself has a tendency to kill
848 performance. We instead put it in a proxy and return it from
849 this method. It is legal for this method to return self
850 if no new functionality is needed for Environment substitution.
855 if not self.exists():
856 return "building `%s' because it doesn't exist\n" % self
858 old = self.get_stored_info()
862 def dictify(result, kids, sigs):
863 for k, s in zip(kids, sigs):
867 old_bkids = old.bsources + old.bdepends + old.bimplicit
868 except AttributeError:
869 return "Cannot explain why `%s' is being rebuilt: No previous build information found\n" % self
872 dictify(osig, old.bsources, old.bsourcesigs)
873 dictify(osig, old.bdepends, old.bdependsigs)
874 dictify(osig, old.bimplicit, old.bimplicitsigs)
876 new_bsources = map(str, self.binfo.bsources)
877 new_bdepends = map(str, self.binfo.bdepends)
878 new_bimplicit = map(str, self.binfo.bimplicit)
881 dictify(nsig, new_bsources, self.binfo.bsourcesigs)
882 dictify(nsig, new_bdepends, self.binfo.bdependsigs)
883 dictify(nsig, new_bimplicit, self.binfo.bimplicitsigs)
885 new_bkids = new_bsources + new_bdepends + new_bimplicit
886 lines = map(lambda x: "`%s' is no longer a dependency\n" % x,
887 filter(lambda x, nk=new_bkids: not x in nk, old_bkids))
890 if not k in old_bkids:
891 lines.append("`%s' is a new dependency\n" % k)
892 elif osig[k] != nsig[k]:
893 lines.append("`%s' changed\n" % k)
895 if len(lines) == 0 and old_bkids != new_bkids:
896 lines.append("the dependency order changed:\n" +
897 "%sold: %s\n" % (' '*15, old_bkids) +
898 "%snew: %s\n" % (' '*15, new_bkids))
901 newact, newactsig = self.binfo.bact, self.binfo.bactsig
902 if old.bact != newact:
903 lines.append("the build action changed:\n" +
904 "%sold: %s\n" % (' '*15, old.bact) +
905 "%snew: %s\n" % (' '*15, newact))
908 return "rebuilding `%s' for unknown reasons" % self
910 preamble = "rebuilding `%s' because" % self
912 return "%s %s" % (preamble, lines[0])
914 lines = ["%s:\n" % preamble] + lines
915 return string.join(lines, ' '*11)
917 def get_children(node, parent): return node.children()
918 def ignore_cycle(node, stack): pass
919 def do_nothing(node, parent): pass
922 """An iterator for walking a Node tree.
924 This is depth-first, children are visited before the parent.
925 The Walker object can be initialized with any node, and
926 returns the next node on the descent with each next() call.
927 'kids_func' is an optional function that will be called to
928 get the children of a node instead of calling 'children'.
929 'cycle_func' is an optional function that will be called
930 when a cycle is detected.
932 This class does not get caught in node cycles caused, for example,
933 by C header file include loops.
935 def __init__(self, node, kids_func=get_children,
936 cycle_func=ignore_cycle,
937 eval_func=do_nothing):
938 self.kids_func = kids_func
939 self.cycle_func = cycle_func
940 self.eval_func = eval_func
941 node.wkids = copy.copy(kids_func(node, None))
943 self.history = {} # used to efficiently detect and avoid cycles
944 self.history[node] = None
947 """Return the next node for this walk of the tree.
949 This function is intentionally iterative, not recursive,
950 to sidestep any issues of stack size limitations.
954 if self.stack[-1].wkids:
955 node = self.stack[-1].wkids.pop(0)
956 if not self.stack[-1].wkids:
957 self.stack[-1].wkids = None
958 if self.history.has_key(node):
959 self.cycle_func(node, self.stack)
961 node.wkids = copy.copy(self.kids_func(node, self.stack[-1]))
962 self.stack.append(node)
963 self.history[node] = None
965 node = self.stack.pop()
966 del self.history[node]
969 parent = self.stack[-1]
972 self.eval_func(node, parent)
977 return not self.stack
980 arg2nodes_lookups = []