mapnik/scons/scons-local-0.96.1/SCons/Node/__init__.py
2006-01-31 23:09:52 +00:00

980 lines
34 KiB
Python

"""SCons.Node
The Node package for the SCons software construction utility.
This is, in many ways, the heart of SCons.
A Node is where we encapsulate all of the dependency information about
any thing that SCons can build, or about any thing which SCons can use
to build some other thing. The canonical "thing," of course, is a file,
but a Node can also represent something remote (like a web page) or
something completely abstract (like an Alias).
Each specific type of "thing" is specifically represented by a subclass
of the Node base class: Node.FS.File for files, Node.Alias for aliases,
etc. Dependency information is kept here in the base class, and
information specific to files/aliases/etc. is in the subclass. The
goal, if we've done this correctly, is that any type of "thing" should
be able to depend on any other type of "thing."
"""
#
# Copyright (c) 2001, 2002, 2003, 2004 The SCons Foundation
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be included
# in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
# KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
# WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
#
__revision__ = "/home/scons/scons/branch.0/baseline/src/engine/SCons/Node/__init__.py 0.96.1.D001 2004/08/23 09:55:29 knight"
import copy
import string
from SCons.Debug import logInstanceCreation
import SCons.SConsign
import SCons.Util
# Node states
#
# These are in "priority" order, so that the maximum value for any
# child/dependency of a node represents the state of that node if
# it has no builder of its own. The canonical example is a file
# system directory, which is only up to date if all of its children
# were up to date.
pending = 1
executing = 2
up_to_date = 3
executed = 4
failed = 5
stack = 6 # nodes that are in the current Taskmaster execution stack
# controls whether implicit depedencies are cached:
implicit_cache = 0
# controls whether implicit dep changes are ignored:
implicit_deps_unchanged = 0
# controls whether the cached implicit deps are ignored:
implicit_deps_changed = 0
# A variable that can be set to an interface-specific function be called
# to annotate a Node with information about its creation.
def do_nothing(node): pass
Annotate = do_nothing
class BuildInfo:
def __cmp__(self, other):
return cmp(self.__dict__, other.__dict__)
class Node:
"""The base Node class, for entities that we know how to
build, or use to build other Nodes.
"""
class Attrs:
pass
def __init__(self):
if __debug__: logInstanceCreation(self, 'Node')
# Note that we no longer explicitly initialize a self.builder
# attribute to None here. That's because the self.builder
# attribute may be created on-the-fly later by a subclass (the
# canonical example being a builder to fetch a file from a
# source code system like CVS or Subversion).
# Each list of children that we maintain is accompanied by a
# dictionary used to look up quickly whether a node is already
# present in the list. Empirical tests showed that it was
# fastest to maintain them as side-by-side Node attributes in
# this way, instead of wrapping up each list+dictionary pair in
# a class. (Of course, we could always still do that in the
# future if we had a good reason to...).
self.sources = [] # source files used to build node
self.sources_dict = {}
self.depends = [] # explicit dependencies (from Depends)
self.depends_dict = {}
self.ignore = [] # dependencies to ignore
self.ignore_dict = {}
self.implicit = None # implicit (scanned) dependencies (None means not scanned yet)
self.waiting_parents = []
self.wkids = None # Kids yet to walk, when it's an array
self.target_scanner = None # explicit scanner from this node's Builder
self.source_scanner = None
self.backup_source_scanner = None
self.env = None
self.state = None
self.precious = None
self.always_build = None
self.found_includes = {}
self.includes = None
self.overrides = {} # construction variable overrides for building this node
self.attributes = self.Attrs() # Generic place to stick information about the Node.
self.side_effect = 0 # true iff this node is a side effect
self.side_effects = [] # the side effects of building this target
self.pre_actions = []
self.post_actions = []
self.linked = 0 # is this node linked to the build directory?
# Let the interface in which the build engine is embedded
# annotate this Node with its own info (like a description of
# what line in what file created the node, for example).
Annotate(self)
def get_suffix(self):
return ''
def generate_build_dict(self):
"""Return an appropriate dictionary of values for building
this Node."""
return {}
def get_build_env(self):
"""Fetch the appropriate Environment to build this node."""
executor = self.get_executor()
return executor.get_build_env()
def set_executor(self, executor):
"""Set the action executor for this node."""
self.executor = executor
def get_executor(self, create=1):
"""Fetch the action executor for this node. Create one if
there isn't already one, and requested to do so."""
try:
executor = self.executor
except AttributeError:
if not create:
raise
import SCons.Executor
executor = SCons.Executor.Executor(self.builder.action,
self.builder.env,
[self.builder.overrides],
[self],
self.sources)
self.executor = executor
return executor
def retrieve_from_cache(self):
"""Try to retrieve the node's content from a cache
This method is called from multiple threads in a parallel build,
so only do thread safe stuff here. Do thread unsafe stuff in
built().
Returns true iff the node was successfully retrieved.
"""
return 0
def build(self, **kw):
"""Actually build the node.
This method is called from multiple threads in a parallel build,
so only do thread safe stuff here. Do thread unsafe stuff in
built().
"""
if not self.has_builder():
return
def errfunc(stat, node=self):
raise SCons.Errors.BuildError(node=node, errstr="Error %d" % stat)
executor = self.get_executor()
apply(executor, (self, errfunc), kw)
def built(self):
"""Called just after this node is sucessfully built."""
try:
new_binfo = self.binfo
except AttributeError:
pass
else:
self.store_info(new_binfo)
# Clear our scanned included files.
self.found_includes = {}
self.includes = None
# Clear the implicit dependency caches of any Nodes
# waiting for this Node to be built.
for parent in self.waiting_parents:
parent.implicit = None
parent.del_binfo()
self.waiting_parents = []
# The content just changed, delete any cached info
# so it will get recalculated.
self.del_cinfo()
def add_to_waiting_parents(self, node):
self.waiting_parents.append(node)
def call_for_all_waiting_parents(self, func):
func(self)
for parent in self.waiting_parents:
parent.call_for_all_waiting_parents(func)
def postprocess(self):
"""Clean up anything we don't need to hang onto after we've
been built."""
try:
executor = self.get_executor(create=None)
except AttributeError:
pass
else:
executor.cleanup()
def clear(self):
"""Completely clear a Node of all its cached state (so that it
can be re-evaluated by interfaces that do continuous integration
builds).
"""
self.set_state(None)
self.del_binfo()
self.del_cinfo()
try:
delattr(self, '_calculated_sig')
except AttributeError:
pass
self.includes = None
self.found_includes = {}
self.implicit = None
self.waiting_parents = []
def visited(self):
"""Called just after this node has been visited
without requiring a build.."""
pass
def depends_on(self, nodes):
"""Does this node depend on any of 'nodes'?"""
for node in nodes:
if node in self.children():
return 1
return 0
def builder_set(self, builder):
self.builder = builder
def has_builder(self):
"""Return whether this Node has a builder or not.
In Boolean tests, this turns out to be a *lot* more efficient
than simply examining the builder attribute directly ("if
node.builder: ..."). When the builder attribute is examined
directly, it ends up calling __getattr__ for both the __len__
and __nonzero__ attributes on instances of our Builder Proxy
class(es), generating a bazillion extra calls and slowing
things down immensely.
"""
try:
b = self.builder
except AttributeError:
# There was no explicit builder for this Node, so initialize
# the self.builder attribute to None now.
self.builder = None
b = self.builder
return not b is None
multiple_side_effect_has_builder = has_builder
def is_derived(self):
"""
Returns true iff this node is derived (i.e. built).
This should return true only for nodes whose path should be in
the build directory when duplicate=0 and should contribute their build
signatures when they are used as source files to other derived files. For
example: source with source builders are not derived in this sense,
and hence should not return true.
"""
return self.has_builder() or self.side_effect
def is_pseudo_derived(self):
"""
Returns true iff this node is built, but should use a source path
when duplicate=0 and should contribute a content signature (i.e.
source signature) when used as a source for other derived files.
"""
return 0
def alter_targets(self):
"""Return a list of alternate targets for this Node.
"""
return [], None
def get_found_includes(self, env, scanner, target):
"""Return the scanned include lines (implicit dependencies)
found in this node.
The default is no implicit dependencies. We expect this method
to be overridden by any subclass that can be scanned for
implicit dependencies.
"""
return []
def get_implicit_deps(self, env, scanner, target):
"""Return a list of implicit dependencies for this node.
This method exists to handle recursive invocation of the scanner
on the implicit dependencies returned by the scanner, if the
scanner's recursive flag says that we should.
"""
if not scanner:
return []
# Give the scanner a chance to select a more specific scanner
# for this Node.
scanner = scanner.select(self)
try:
recurse = scanner.recursive
except AttributeError:
recurse = None
nodes = [self]
seen = {}
seen[self] = 1
deps = []
while nodes:
n = nodes.pop(0)
d = filter(lambda x, seen=seen: not seen.has_key(x),
n.get_found_includes(env, scanner, target))
if d:
deps.extend(d)
for n in d:
seen[n] = 1
if recurse:
nodes.extend(d)
return deps
# cache used to make implicit_factory fast.
implicit_factory_cache = {}
def implicit_factory(self, path):
"""
Turn a cache implicit dependency path into a node.
This is called so many times that doing caching
here is a significant perforamnce boost.
"""
try:
return self.implicit_factory_cache[path]
except KeyError:
n = self.builder.source_factory(path)
self.implicit_factory_cache[path] = n
return n
def get_source_scanner(self, node):
"""Fetch the source scanner for the specified node
NOTE: "self" is the target being built, "node" is
the source file for which we want to fetch the scanner.
"""
if self.source_scanner:
return self.source_scanner
try:
scanner = node.builder.source_scanner
if scanner:
return scanner
except AttributeError:
pass
return node.backup_source_scanner or None
def scan(self):
"""Scan this node's dependents for implicit dependencies."""
# Don't bother scanning non-derived files, because we don't
# care what their dependencies are.
# Don't scan again, if we already have scanned.
if not self.implicit is None:
return
self.implicit = []
self.implicit_dict = {}
self._children_reset()
if not self.has_builder():
return
build_env = self.get_build_env()
# Here's where we implement --implicit-cache.
if implicit_cache and not implicit_deps_changed:
implicit = self.get_stored_implicit()
if implicit is not None:
implicit = map(self.implicit_factory, implicit)
self._add_child(self.implicit, self.implicit_dict, implicit)
calc = build_env.get_calculator()
if implicit_deps_unchanged or self.current(calc, scan=0):
return
else:
# one of this node's sources has changed, so
# we need to recalculate the implicit deps,
# and the bsig:
self.implicit = []
self.implicit_dict = {}
self._children_reset()
self.del_binfo()
for child in self.children(scan=0):
scanner = self.get_source_scanner(child)
if scanner:
deps = child.get_implicit_deps(build_env, scanner, self)
self._add_child(self.implicit, self.implicit_dict, deps)
# scan this node itself for implicit dependencies
deps = self.get_implicit_deps(build_env, self.target_scanner, self)
self._add_child(self.implicit, self.implicit_dict, deps)
# XXX See note above re: --implicit-cache.
#if implicit_cache:
# self.store_implicit()
def scanner_key(self):
return None
def env_set(self, env, safe=0):
if safe and self.env:
return
self.env = env
def calculator(self):
import SCons.Defaults
env = self.env or SCons.Defaults.DefaultEnvironment()
return env.get_calculator()
def calc_signature(self, calc=None):
"""
Select and calculate the appropriate build signature for a node.
self - the node
calc - the signature calculation module
returns - the signature
"""
try:
return self._calculated_sig
except AttributeError:
if self.is_derived():
import SCons.Defaults
env = self.env or SCons.Defaults.DefaultEnvironment()
if env.use_build_signature():
sig = self.calc_bsig(calc)
else:
sig = self.calc_csig(calc)
elif not self.rexists():
sig = None
else:
sig = self.calc_csig(calc)
self._calculated_sig = sig
return sig
def new_binfo(self):
return BuildInfo()
def del_binfo(self):
"""Delete the bsig from this node."""
try:
delattr(self, 'binfo')
except AttributeError:
pass
def calc_bsig(self, calc=None):
try:
return self.binfo.bsig
except AttributeError:
self.binfo = self.gen_binfo(calc)
return self.binfo.bsig
def gen_binfo(self, calc=None, scan=1):
"""
Generate a node's build signature, the digested signatures
of its dependency files and build information.
node - the node whose sources will be collected
cache - alternate node to use for the signature cache
returns - the build signature
This no longer handles the recursive descent of the
node's children's signatures. We expect that they're
already built and updated by someone else, if that's
what's wanted.
"""
if calc is None:
calc = self.calculator()
binfo = self.new_binfo()
if scan:
self.scan()
sources = self.filter_ignore(self.sources)
depends = self.filter_ignore(self.depends)
if self.implicit is None:
implicit = []
else:
implicit = self.filter_ignore(self.implicit)
def calc_signature(node, calc=calc):
return node.calc_signature(calc)
sourcesigs = map(calc_signature, sources)
dependsigs = map(calc_signature, depends)
implicitsigs = map(calc_signature, implicit)
sigs = sourcesigs + dependsigs + implicitsigs
if self.has_builder():
executor = self.get_executor()
binfo.bact = executor.get_contents()
binfo.bactsig = calc.module.signature(executor)
sigs.append(binfo.bactsig)
binfo.bsources = map(str, sources)
binfo.bdepends = map(str, depends)
binfo.bimplicit = map(str, implicit)
binfo.bsourcesigs = sourcesigs
binfo.bdependsigs = dependsigs
binfo.bimplicitsigs = implicitsigs
binfo.bsig = calc.module.collect(filter(None, sigs))
return binfo
def del_cinfo(self):
try:
del self.binfo.csig
except AttributeError:
pass
def calc_csig(self, calc=None):
try:
binfo = self.binfo
except AttributeError:
binfo = self.binfo = self.new_binfo()
try:
return binfo.csig
except AttributeError:
if calc is None:
calc = self.calculator()
binfo.csig = calc.module.signature(self)
self.store_info(binfo)
return binfo.csig
def store_info(self, obj):
"""Make the build signature permanent (that is, store it in the
.sconsign file or equivalent)."""
pass
def get_stored_info(self):
return None
def get_stored_implicit(self):
"""Fetch the stored implicit dependencies"""
return None
def set_precious(self, precious = 1):
"""Set the Node's precious value."""
self.precious = precious
def set_always_build(self, always_build = 1):
"""Set the Node's always_build value."""
self.always_build = always_build
def exists(self):
"""Does this node exists?"""
# All node exist by default:
return 1
def rexists(self):
"""Does this node exist locally or in a repositiory?"""
# There are no repositories by default:
return self.exists()
def prepare(self):
"""Prepare for this Node to be created.
The default implemenation checks that all children either exist
or are derived.
"""
def missing(node):
return not node.is_derived() and \
not node.is_pseudo_derived() and \
not node.linked and \
not node.rexists()
missing_sources = filter(missing, self.children())
if missing_sources:
desc = "Source `%s' not found, needed by target `%s'." % (missing_sources[0], self)
raise SCons.Errors.StopError, desc
def remove(self):
"""Remove this Node: no-op by default."""
return None
def add_dependency(self, depend):
"""Adds dependencies."""
try:
self._add_child(self.depends, self.depends_dict, depend)
except TypeError, e:
e = e.args[0]
if SCons.Util.is_List(e):
s = map(str, e)
else:
s = str(e)
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)))
def add_ignore(self, depend):
"""Adds dependencies to ignore."""
try:
self._add_child(self.ignore, self.ignore_dict, depend)
except TypeError, e:
e = e.args[0]
if SCons.Util.is_List(e):
s = map(str, e)
else:
s = str(e)
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)))
def add_source(self, source):
"""Adds sources."""
try:
self._add_child(self.sources, self.sources_dict, source)
except TypeError, e:
e = e.args[0]
if SCons.Util.is_List(e):
s = map(str, e)
else:
s = str(e)
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)))
def _add_child(self, collection, dict, child):
"""Adds 'child' to 'collection', first checking 'dict' to see
if it's already present."""
if type(child) is not type([]):
child = [child]
for c in child:
if not isinstance(c, Node):
raise TypeError, c
added = None
for c in child:
if not dict.has_key(c):
collection.append(c)
dict[c] = 1
added = 1
if added:
self._children_reset()
def add_wkid(self, wkid):
"""Add a node to the list of kids waiting to be evaluated"""
if self.wkids != None:
self.wkids.append(wkid)
def _children_reset(self):
try:
delattr(self, '_children')
except AttributeError:
pass
def filter_ignore(self, nodelist):
ignore = self.ignore
result = []
for node in nodelist:
if node not in ignore:
result.append(node)
return result
def children(self, scan=1):
"""Return a list of the node's direct children, minus those
that are ignored by this node."""
if scan:
self.scan()
try:
return self._children
except AttributeError:
c = self.all_children(scan=0)
self._children = self.filter_ignore(c)
return self._children
def all_children(self, scan=1):
"""Return a list of all the node's direct children."""
# The return list may contain duplicate Nodes, especially in
# source trees where there are a lot of repeated #includes
# of a tangle of .h files. Profiling shows, however, that
# eliminating the duplicates with a brute-force approach that
# preserves the order (that is, something like:
#
# u = []
# for n in list:
# if n not in u:
# u.append(n)"
#
# takes more cycles than just letting the underlying methods
# hand back cached values if a Node's information is requested
# multiple times. (Other methods of removing duplicates, like
# using dictionary keys, lose the order, and the only ordered
# dictionary patterns I found all ended up using "not in"
# internally anyway...)
if scan:
self.scan()
if self.implicit is None:
return self.sources + self.depends
else:
return self.sources + self.depends + self.implicit
def set_state(self, state):
self.state = state
def get_state(self):
return self.state
def current(self, calc=None):
"""Default check for whether the Node is current: unknown Node
subtypes are always out of date, so they will always get built."""
return None
def children_are_up_to_date(self, calc=None):
"""Alternate check for whether the Node is current: If all of
our children were up-to-date, then this Node was up-to-date, too.
The SCons.Node.Alias and SCons.Node.Python.Value subclasses
rebind their current() method to this method."""
# Allow the children to calculate their signatures.
self.binfo = self.gen_binfo(calc)
state = 0
for kid in self.children(None):
s = kid.get_state()
if s and (not state or s > state):
state = s
return (state == 0 or state == SCons.Node.up_to_date)
def is_literal(self):
"""Always pass the string representation of a Node to
the command interpreter literally."""
return 1
def add_pre_action(self, act):
"""Adds an Action performed on this Node only before
building it."""
self.pre_actions.append(act)
def add_post_action(self, act):
"""Adds and Action performed on this Node only after
building it."""
self.post_actions.append(act)
def render_include_tree(self):
"""
Return a text representation, suitable for displaying to the
user, of the include tree for the sources of this node.
"""
if self.is_derived() and self.env:
env = self.get_build_env()
for s in self.sources:
scanner = s.get_source_scanner(self)
def f(node, env=env, scanner=scanner, target=self):
return node.get_found_includes(env, scanner, target)
return SCons.Util.render_tree(s, f, 1)
else:
return None
def get_abspath(self):
"""
Return an absolute path to the Node. This will return simply
str(Node) by default, but for Node types that have a concept of
relative path, this might return something different.
"""
return str(self)
def for_signature(self):
"""
Return a string representation of the Node that will always
be the same for this particular Node, no matter what. This
is by contrast to the __str__() method, which might, for
instance, return a relative path for a file Node. The purpose
of this method is to generate a value to be used in signature
calculation for the command line used to build a target, and
we use this method instead of str() to avoid unnecessary
rebuilds. This method does not need to return something that
would actually work in a command line; it can return any kind of
nonsense, so long as it does not change.
"""
return str(self)
def get_string(self, for_signature):
"""This is a convenience function designed primarily to be
used in command generators (i.e., CommandGeneratorActions or
Environment variables that are callable), which are called
with a for_signature argument that is nonzero if the command
generator is being called to generate a signature for the
command line, which determines if we should rebuild or not.
Such command generators shoud use this method in preference
to str(Node) when converting a Node to a string, passing
in the for_signature parameter, such that we will call
Node.for_signature() or str(Node) properly, depending on whether
we are calculating a signature or actually constructing a
command line."""
if for_signature:
return self.for_signature()
return str(self)
def get_subst_proxy(self):
"""
This method is expected to return an object that will function
exactly like this Node, except that it implements any additional
special features that we would like to be in effect for
Environment variable substitution. The principle use is that
some Nodes would like to implement a __getattr__() method,
but putting that in the Node type itself has a tendency to kill
performance. We instead put it in a proxy and return it from
this method. It is legal for this method to return self
if no new functionality is needed for Environment substitution.
"""
return self
def explain(self):
if not self.exists():
return "building `%s' because it doesn't exist\n" % self
old = self.get_stored_info()
if old is None:
return None
def dictify(result, kids, sigs):
for k, s in zip(kids, sigs):
result[k] = s
try:
old_bkids = old.bsources + old.bdepends + old.bimplicit
except AttributeError:
return "Cannot explain why `%s' is being rebuilt: No previous build information found\n" % self
osig = {}
dictify(osig, old.bsources, old.bsourcesigs)
dictify(osig, old.bdepends, old.bdependsigs)
dictify(osig, old.bimplicit, old.bimplicitsigs)
new_bsources = map(str, self.binfo.bsources)
new_bdepends = map(str, self.binfo.bdepends)
new_bimplicit = map(str, self.binfo.bimplicit)
nsig = {}
dictify(nsig, new_bsources, self.binfo.bsourcesigs)
dictify(nsig, new_bdepends, self.binfo.bdependsigs)
dictify(nsig, new_bimplicit, self.binfo.bimplicitsigs)
new_bkids = new_bsources + new_bdepends + new_bimplicit
lines = map(lambda x: "`%s' is no longer a dependency\n" % x,
filter(lambda x, nk=new_bkids: not x in nk, old_bkids))
for k in new_bkids:
if not k in old_bkids:
lines.append("`%s' is a new dependency\n" % k)
elif osig[k] != nsig[k]:
lines.append("`%s' changed\n" % k)
if len(lines) == 0 and old_bkids != new_bkids:
lines.append("the dependency order changed:\n" +
"%sold: %s\n" % (' '*15, old_bkids) +
"%snew: %s\n" % (' '*15, new_bkids))
if len(lines) == 0:
newact, newactsig = self.binfo.bact, self.binfo.bactsig
if old.bact != newact:
lines.append("the build action changed:\n" +
"%sold: %s\n" % (' '*15, old.bact) +
"%snew: %s\n" % (' '*15, newact))
if len(lines) == 0:
return "rebuilding `%s' for unknown reasons" % self
preamble = "rebuilding `%s' because" % self
if len(lines) == 1:
return "%s %s" % (preamble, lines[0])
else:
lines = ["%s:\n" % preamble] + lines
return string.join(lines, ' '*11)
def get_children(node, parent): return node.children()
def ignore_cycle(node, stack): pass
def do_nothing(node, parent): pass
class Walker:
"""An iterator for walking a Node tree.
This is depth-first, children are visited before the parent.
The Walker object can be initialized with any node, and
returns the next node on the descent with each next() call.
'kids_func' is an optional function that will be called to
get the children of a node instead of calling 'children'.
'cycle_func' is an optional function that will be called
when a cycle is detected.
This class does not get caught in node cycles caused, for example,
by C header file include loops.
"""
def __init__(self, node, kids_func=get_children,
cycle_func=ignore_cycle,
eval_func=do_nothing):
self.kids_func = kids_func
self.cycle_func = cycle_func
self.eval_func = eval_func
node.wkids = copy.copy(kids_func(node, None))
self.stack = [node]
self.history = {} # used to efficiently detect and avoid cycles
self.history[node] = None
def next(self):
"""Return the next node for this walk of the tree.
This function is intentionally iterative, not recursive,
to sidestep any issues of stack size limitations.
"""
while self.stack:
if self.stack[-1].wkids:
node = self.stack[-1].wkids.pop(0)
if not self.stack[-1].wkids:
self.stack[-1].wkids = None
if self.history.has_key(node):
self.cycle_func(node, self.stack)
else:
node.wkids = copy.copy(self.kids_func(node, self.stack[-1]))
self.stack.append(node)
self.history[node] = None
else:
node = self.stack.pop()
del self.history[node]
if node:
if self.stack:
parent = self.stack[-1]
else:
parent = None
self.eval_func(node, parent)
return node
return None
def is_done(self):
return not self.stack
arg2nodes_lookups = []