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 # controls whether --debug=explain info is saved in Nodes:
82 # A variable that can be set to an interface-specific function be called
83 # to annotate a Node with information about its creation.
84 def do_nothing(node): pass
89 def __cmp__(self, other):
90 return cmp(self.__dict__, other.__dict__)
93 """The base Node class, for entities that we know how to
94 build, or use to build other Nodes.
101 if __debug__: logInstanceCreation(self, 'Node')
102 # Note that we no longer explicitly initialize a self.builder
103 # attribute to None here. That's because the self.builder
104 # attribute may be created on-the-fly later by a subclass (the
105 # canonical example being a builder to fetch a file from a
106 # source code system like CVS or Subversion).
108 # Each list of children that we maintain is accompanied by a
109 # dictionary used to look up quickly whether a node is already
110 # present in the list. Empirical tests showed that it was
111 # fastest to maintain them as side-by-side Node attributes in
112 # this way, instead of wrapping up each list+dictionary pair in
113 # a class. (Of course, we could always still do that in the
114 # future if we had a good reason to...).
115 self.sources = [] # source files used to build node
116 self.sources_dict = {}
117 self.depends = [] # explicit dependencies (from Depends)
118 self.depends_dict = {}
119 self.ignore = [] # dependencies to ignore
120 self.ignore_dict = {}
121 self.implicit = None # implicit (scanned) dependencies (None means not scanned yet)
122 self.waiting_parents = []
123 self.wkids = None # Kids yet to walk, when it's an array
124 self.target_scanner = None # explicit scanner from this node's Builder
125 self.source_scanner = None
126 self.backup_source_scanner = None
131 self.always_build = None
132 self.found_includes = {}
134 self.overrides = {} # construction variable overrides for building this node
135 self.attributes = self.Attrs() # Generic place to stick information about the Node.
136 self.side_effect = 0 # true iff this node is a side effect
137 self.side_effects = [] # the side effects of building this target
138 self.pre_actions = []
139 self.post_actions = []
140 self.linked = 0 # is this node linked to the build directory?
142 # Let the interface in which the build engine is embedded
143 # annotate this Node with its own info (like a description of
144 # what line in what file created the node, for example).
147 def get_suffix(self):
150 def generate_build_dict(self):
151 """Return an appropriate dictionary of values for building
155 def get_build_env(self):
156 """Fetch the appropriate Environment to build this node."""
157 executor = self.get_executor()
158 return executor.get_build_env()
160 def set_executor(self, executor):
161 """Set the action executor for this node."""
162 self.executor = executor
164 def get_executor(self, create=1):
165 """Fetch the action executor for this node. Create one if
166 there isn't already one, and requested to do so."""
168 executor = self.executor
169 except AttributeError:
172 import SCons.Executor
173 executor = SCons.Executor.Executor(self.builder.action,
175 [self.builder.overrides],
178 self.executor = executor
181 def retrieve_from_cache(self):
182 """Try to retrieve the node's content from a cache
184 This method is called from multiple threads in a parallel build,
185 so only do thread safe stuff here. Do thread unsafe stuff in
188 Returns true iff the node was successfully retrieved.
192 def build(self, **kw):
193 """Actually build the node.
195 This method is called from multiple threads in a parallel build,
196 so only do thread safe stuff here. Do thread unsafe stuff in
199 if not self.has_builder():
201 def errfunc(stat, node=self):
202 raise SCons.Errors.BuildError(node=node, errstr="Error %d" % stat)
203 executor = self.get_executor()
204 apply(executor, (self, errfunc), kw)
207 """Called just after this node is sucessfully built."""
209 new_binfo = self.binfo
210 except AttributeError:
213 self.store_info(new_binfo)
215 # Clear our scanned included files.
216 self.found_includes = {}
219 # Clear the implicit dependency caches of any Nodes
220 # waiting for this Node to be built.
221 for parent in self.waiting_parents:
222 parent.implicit = None
224 self.waiting_parents = []
226 # The content just changed, delete any cached info
227 # so it will get recalculated.
230 def add_to_waiting_parents(self, node):
231 self.waiting_parents.append(node)
233 def call_for_all_waiting_parents(self, func):
235 for parent in self.waiting_parents:
236 parent.call_for_all_waiting_parents(func)
238 def postprocess(self):
239 """Clean up anything we don't need to hang onto after we've
242 executor = self.get_executor(create=None)
243 except AttributeError:
249 """Completely clear a Node of all its cached state (so that it
250 can be re-evaluated by interfaces that do continuous integration
257 delattr(self, '_calculated_sig')
258 except AttributeError:
261 self.found_includes = {}
264 self.waiting_parents = []
267 """Called just after this node has been visited
268 without requiring a build.."""
271 def depends_on(self, nodes):
272 """Does this node depend on any of 'nodes'?"""
274 if node in self.children():
279 def builder_set(self, builder):
280 self.builder = builder
282 def has_builder(self):
283 """Return whether this Node has a builder or not.
285 In Boolean tests, this turns out to be a *lot* more efficient
286 than simply examining the builder attribute directly ("if
287 node.builder: ..."). When the builder attribute is examined
288 directly, it ends up calling __getattr__ for both the __len__
289 and __nonzero__ attributes on instances of our Builder Proxy
290 class(es), generating a bazillion extra calls and slowing
291 things down immensely.
295 except AttributeError:
296 # There was no explicit builder for this Node, so initialize
297 # the self.builder attribute to None now.
302 def is_derived(self):
304 Returns true iff this node is derived (i.e. built).
306 This should return true only for nodes whose path should be in
307 the build directory when duplicate=0 and should contribute their build
308 signatures when they are used as source files to other derived files. For
309 example: source with source builders are not derived in this sense,
310 and hence should not return true.
312 return self.has_builder() or self.side_effect
314 def is_pseudo_derived(self):
316 Returns true iff this node is built, but should use a source path
317 when duplicate=0 and should contribute a content signature (i.e.
318 source signature) when used as a source for other derived files.
322 def alter_targets(self):
323 """Return a list of alternate targets for this Node.
327 def get_found_includes(self, env, scanner, target):
328 """Return the scanned include lines (implicit dependencies)
331 The default is no implicit dependencies. We expect this method
332 to be overridden by any subclass that can be scanned for
333 implicit dependencies.
337 def get_implicit_deps(self, env, scanner, target):
338 """Return a list of implicit dependencies for this node.
340 This method exists to handle recursive invocation of the scanner
341 on the implicit dependencies returned by the scanner, if the
342 scanner's recursive flag says that we should.
347 # Give the scanner a chance to select a more specific scanner
349 scanner = scanner.select(self)
352 recurse = scanner.recursive
353 except AttributeError:
362 d = filter(lambda x, seen=seen: not seen.has_key(x),
363 n.get_found_includes(env, scanner, target))
373 # cache used to make implicit_factory fast.
374 implicit_factory_cache = {}
376 def implicit_factory(self, path):
378 Turn a cache implicit dependency path into a node.
379 This is called so many times that doing caching
380 here is a significant perforamnce boost.
383 return self.implicit_factory_cache[path]
385 n = self.builder.source_factory(path)
386 self.implicit_factory_cache[path] = n
389 def get_source_scanner(self, node):
390 """Fetch the source scanner for the specified node
392 NOTE: "self" is the target being built, "node" is
393 the source file for which we want to fetch the scanner.
395 if self.source_scanner:
396 return self.source_scanner
398 scanner = node.builder.source_scanner
401 except AttributeError:
403 return node.backup_source_scanner or None
406 """Scan this node's dependents for implicit dependencies."""
407 # Don't bother scanning non-derived files, because we don't
408 # care what their dependencies are.
409 # Don't scan again, if we already have scanned.
410 if not self.implicit is None:
413 self.implicit_dict = {}
414 self._children_reset()
415 if not self.has_builder():
418 build_env = self.get_build_env()
420 # XXX Here's where we implement --implicit-cache. This doesn't
421 # do anything right now, but we're probably going to re-implement
422 # as a way to cache #include lines from source files, so I want
423 # to keep this code around for now.
425 #if implicit_cache and not implicit_deps_changed:
426 # implicit = self.get_stored_implicit()
427 # if implicit is not None:
428 # implicit = map(self.implicit_factory, implicit)
429 # self._add_child(self.implicit, self.implicit_dict, implicit)
430 # calc = build_env.get_calculator()
431 # if implicit_deps_unchanged or calc.current(self, calc.bsig(self)):
434 # # one of this node's sources has changed, so
435 # # we need to recalculate the implicit deps,
438 # self.implicit_dict = {}
439 # self._children_reset()
442 for child in self.children(scan=0):
443 scanner = self.get_source_scanner(child)
445 deps = child.get_implicit_deps(build_env, scanner, self)
446 self._add_child(self.implicit, self.implicit_dict, deps)
448 # scan this node itself for implicit dependencies
449 deps = self.get_implicit_deps(build_env, self.target_scanner, self)
450 self._add_child(self.implicit, self.implicit_dict, deps)
452 # XXX See note above re: --implicit-cache.
454 # self.store_implicit()
456 def scanner_key(self):
459 def env_set(self, env, safe=0):
460 if safe and self.env:
464 def calculator(self):
465 import SCons.Defaults
467 env = self.env or SCons.Defaults.DefaultEnvironment()
468 return env.get_calculator()
470 def calc_signature(self, calc=None):
472 Select and calculate the appropriate build signature for a node.
475 calc - the signature calculation module
476 returns - the signature
479 return self._calculated_sig
480 except AttributeError:
481 if self.is_derived():
482 import SCons.Defaults
484 env = self.env or SCons.Defaults.DefaultEnvironment()
485 if env.use_build_signature():
486 sig = self.calc_bsig(calc)
488 sig = self.calc_csig(calc)
489 elif not self.rexists():
492 sig = self.calc_csig(calc)
493 self._calculated_sig = sig
500 """Delete the bsig from this node."""
502 delattr(self, 'binfo')
503 except AttributeError:
506 def calc_bsig(self, calc=None):
508 return self.binfo.bsig
509 except AttributeError:
510 self.binfo = self.gen_binfo(calc)
511 return self.binfo.bsig
513 def gen_binfo(self, calc=None):
515 Generate a node's build signature, the digested signatures
516 of its dependency files and build information.
518 node - the node whose sources will be collected
519 cache - alternate node to use for the signature cache
520 returns - the build signature
522 This no longer handles the recursive descent of the
523 node's children's signatures. We expect that they're
524 already built and updated by someone else, if that's
529 calc = self.calculator()
531 binfo = self.new_binfo()
535 sources = self.filter_ignore(self.sources)
536 depends = self.filter_ignore(self.depends)
537 if self.implicit is None:
540 implicit = self.filter_ignore(self.implicit)
542 def calc_signature(node, calc=calc):
543 return node.calc_signature(calc)
544 sourcesigs = map(calc_signature, sources)
545 dependsigs = map(calc_signature, depends)
546 implicitsigs = map(calc_signature, implicit)
548 sigs = sourcesigs + dependsigs + implicitsigs
550 has_builder = self.has_builder()
552 executor = self.get_executor()
553 bactsig = calc.module.signature(executor)
556 if Save_Explain_Info:
557 binfo.bsources = map(str, sources)
558 binfo.bdepends = map(str, depends)
559 binfo.bimplicit = map(str, implicit)
561 binfo.bsourcesigs = sourcesigs
562 binfo.bdependsigs = dependsigs
563 binfo.bimplicitsigs = implicitsigs
566 binfo.bact = executor.get_contents()
567 binfo.bactsig = bactsig
569 binfo.bsig = calc.module.collect(filter(None, sigs))
576 except AttributeError:
579 def calc_csig(self, calc=None):
582 except AttributeError:
583 binfo = self.binfo = self.new_binfo()
586 except AttributeError:
588 calc = self.calculator()
589 binfo.csig = calc.module.signature(self)
590 self.store_info(binfo)
593 def store_info(self, obj):
594 """Make the build signature permanent (that is, store it in the
595 .sconsign file or equivalent)."""
598 def get_stored_info(self):
601 def get_stored_implicit(self):
602 """Fetch the stored implicit dependencies"""
605 def set_precious(self, precious = 1):
606 """Set the Node's precious value."""
607 self.precious = precious
609 def set_always_build(self, always_build = 1):
610 """Set the Node's always_build value."""
611 self.always_build = always_build
614 """Does this node exists?"""
615 # All node exist by default:
619 """Does this node exist locally or in a repositiory?"""
620 # There are no repositories by default:
624 """Prepare for this Node to be created.
625 The default implemenation checks that all children either exist
629 return not node.is_derived() and \
630 not node.is_pseudo_derived() and \
631 not node.linked and \
633 missing_sources = filter(missing, self.children())
635 desc = "Source `%s' not found, needed by target `%s'." % (missing_sources[0], self)
636 raise SCons.Errors.StopError, desc
639 """Remove this Node: no-op by default."""
642 def add_dependency(self, depend):
643 """Adds dependencies."""
645 self._add_child(self.depends, self.depends_dict, depend)
648 if SCons.Util.is_List(e):
652 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)))
654 def add_ignore(self, depend):
655 """Adds dependencies to ignore."""
657 self._add_child(self.ignore, self.ignore_dict, depend)
660 if SCons.Util.is_List(e):
664 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)))
666 def add_source(self, source):
669 self._add_child(self.sources, self.sources_dict, source)
672 if SCons.Util.is_List(e):
676 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)))
678 def _add_child(self, collection, dict, child):
679 """Adds 'child' to 'collection', first checking 'dict' to see
680 if it's already present."""
681 if type(child) is not type([]):
684 if not isinstance(c, Node):
688 if not dict.has_key(c):
693 self._children_reset()
695 def add_wkid(self, wkid):
696 """Add a node to the list of kids waiting to be evaluated"""
697 if self.wkids != None:
698 self.wkids.append(wkid)
700 def _children_reset(self):
702 delattr(self, '_children')
703 except AttributeError:
706 def filter_ignore(self, nodelist):
709 for node in nodelist:
710 if node not in ignore:
714 def children(self, scan=1):
715 """Return a list of the node's direct children, minus those
716 that are ignored by this node."""
720 return self._children
721 except AttributeError:
722 c = self.all_children(scan=0)
723 self._children = self.filter_ignore(c)
724 return self._children
726 def all_children(self, scan=1):
727 """Return a list of all the node's direct children."""
728 # The return list may contain duplicate Nodes, especially in
729 # source trees where there are a lot of repeated #includes
730 # of a tangle of .h files. Profiling shows, however, that
731 # eliminating the duplicates with a brute-force approach that
732 # preserves the order (that is, something like:
739 # takes more cycles than just letting the underlying methods
740 # hand back cached values if a Node's information is requested
741 # multiple times. (Other methods of removing duplicates, like
742 # using dictionary keys, lose the order, and the only ordered
743 # dictionary patterns I found all ended up using "not in"
744 # internally anyway...)
747 if self.implicit is None:
748 return self.sources + self.depends
750 return self.sources + self.depends + self.implicit
752 def set_state(self, state):
758 def current(self, calc=None):
759 """Default check for whether the Node is current: unknown Node
760 subtypes are always out of date, so they will always get built."""
763 def children_are_up_to_date(self, calc=None):
764 """Alternate check for whether the Node is current: If all of
765 our children were up-to-date, then this Node was up-to-date, too.
767 The SCons.Node.Alias and SCons.Node.Python.Value subclasses
768 rebind their current() method to this method."""
769 # Allow the children to calculate their signatures.
770 self.binfo = self.gen_binfo(calc)
772 for kid in self.children(None):
774 if s and (not state or s > state):
776 return (state == 0 or state == SCons.Node.up_to_date)
778 def is_literal(self):
779 """Always pass the string representation of a Node to
780 the command interpreter literally."""
783 def add_pre_action(self, act):
784 """Adds an Action performed on this Node only before
786 self.pre_actions.append(act)
788 def add_post_action(self, act):
789 """Adds and Action performed on this Node only after
791 self.post_actions.append(act)
793 def render_include_tree(self):
795 Return a text representation, suitable for displaying to the
796 user, of the include tree for the sources of this node.
798 if self.is_derived() and self.env:
799 env = self.get_build_env()
800 for s in self.sources:
801 scanner = s.get_source_scanner(self)
802 def f(node, env=env, scanner=scanner, target=self):
803 return node.get_found_includes(env, scanner, target)
804 return SCons.Util.render_tree(s, f, 1)
808 def get_abspath(self):
810 Return an absolute path to the Node. This will return simply
811 str(Node) by default, but for Node types that have a concept of
812 relative path, this might return something different.
816 def for_signature(self):
818 Return a string representation of the Node that will always
819 be the same for this particular Node, no matter what. This
820 is by contrast to the __str__() method, which might, for
821 instance, return a relative path for a file Node. The purpose
822 of this method is to generate a value to be used in signature
823 calculation for the command line used to build a target, and
824 we use this method instead of str() to avoid unnecessary
825 rebuilds. This method does not need to return something that
826 would actually work in a command line; it can return any kind of
827 nonsense, so long as it does not change.
831 def get_string(self, for_signature):
832 """This is a convenience function designed primarily to be
833 used in command generators (i.e., CommandGeneratorActions or
834 Environment variables that are callable), which are called
835 with a for_signature argument that is nonzero if the command
836 generator is being called to generate a signature for the
837 command line, which determines if we should rebuild or not.
839 Such command generators shoud use this method in preference
840 to str(Node) when converting a Node to a string, passing
841 in the for_signature parameter, such that we will call
842 Node.for_signature() or str(Node) properly, depending on whether
843 we are calculating a signature or actually constructing a
846 return self.for_signature()
849 def get_subst_proxy(self):
851 This method is expected to return an object that will function
852 exactly like this Node, except that it implements any additional
853 special features that we would like to be in effect for
854 Environment variable substitution. The principle use is that
855 some Nodes would like to implement a __getattr__() method,
856 but putting that in the Node type itself has a tendency to kill
857 performance. We instead put it in a proxy and return it from
858 this method. It is legal for this method to return self
859 if no new functionality is needed for Environment substitution.
864 if not self.exists():
865 return "building `%s' because it doesn't exist\n" % self
867 old = self.get_stored_info()
871 def dictify(result, kids, sigs):
872 for k, s in zip(kids, sigs):
876 old_bkids = old.bsources + old.bdepends + old.bimplicit
877 except AttributeError:
878 return "Cannot explain why `%s' is being rebuilt: No previous build information found\n" % self
881 dictify(osig, old.bsources, old.bsourcesigs)
882 dictify(osig, old.bdepends, old.bdependsigs)
883 dictify(osig, old.bimplicit, old.bimplicitsigs)
885 new_bsources = map(str, self.binfo.bsources)
886 new_bdepends = map(str, self.binfo.bdepends)
887 new_bimplicit = map(str, self.binfo.bimplicit)
890 dictify(nsig, new_bsources, self.binfo.bsourcesigs)
891 dictify(nsig, new_bdepends, self.binfo.bdependsigs)
892 dictify(nsig, new_bimplicit, self.binfo.bimplicitsigs)
894 new_bkids = new_bsources + new_bdepends + new_bimplicit
895 lines = map(lambda x: "`%s' is no longer a dependency\n" % x,
896 filter(lambda x, nk=new_bkids: not x in nk, old_bkids))
899 if not k in old_bkids:
900 lines.append("`%s' is a new dependency\n" % k)
901 elif osig[k] != nsig[k]:
902 lines.append("`%s' changed\n" % k)
904 if len(lines) == 0 and old_bkids != new_bkids:
905 lines.append("the dependency order changed:\n" +
906 "%sold: %s\n" % (' '*15, old_bkids) +
907 "%snew: %s\n" % (' '*15, new_bkids))
910 newact, newactsig = self.binfo.bact, self.binfo.bactsig
911 if old.bact != newact:
912 lines.append("the build action changed:\n" +
913 "%sold: %s\n" % (' '*15, old.bact) +
914 "%snew: %s\n" % (' '*15, newact))
917 return "rebuilding `%s' for unknown reasons" % self
919 preamble = "rebuilding `%s' because" % self
921 return "%s %s" % (preamble, lines[0])
923 lines = ["%s:\n" % preamble] + lines
924 return string.join(lines, ' '*11)
926 def get_children(node, parent): return node.children()
927 def ignore_cycle(node, stack): pass
928 def do_nothing(node, parent): pass
931 """An iterator for walking a Node tree.
933 This is depth-first, children are visited before the parent.
934 The Walker object can be initialized with any node, and
935 returns the next node on the descent with each next() call.
936 'kids_func' is an optional function that will be called to
937 get the children of a node instead of calling 'children'.
938 'cycle_func' is an optional function that will be called
939 when a cycle is detected.
941 This class does not get caught in node cycles caused, for example,
942 by C header file include loops.
944 def __init__(self, node, kids_func=get_children,
945 cycle_func=ignore_cycle,
946 eval_func=do_nothing):
947 self.kids_func = kids_func
948 self.cycle_func = cycle_func
949 self.eval_func = eval_func
950 node.wkids = copy.copy(kids_func(node, None))
952 self.history = {} # used to efficiently detect and avoid cycles
953 self.history[node] = None
956 """Return the next node for this walk of the tree.
958 This function is intentionally iterative, not recursive,
959 to sidestep any issues of stack size limitations.
963 if self.stack[-1].wkids:
964 node = self.stack[-1].wkids.pop(0)
965 if not self.stack[-1].wkids:
966 self.stack[-1].wkids = None
967 if self.history.has_key(node):
968 self.cycle_func(node, self.stack)
970 node.wkids = copy.copy(self.kids_func(node, self.stack[-1]))
971 self.stack.append(node)
972 self.history[node] = None
974 node = self.stack.pop()
975 del self.history[node]
978 parent = self.stack[-1]
981 self.eval_func(node, parent)
986 return not self.stack
989 arg2nodes_lookups = []