waf

Build.py (43783B)

---

 #!/usr/bin/env python
 # encoding: utf-8
 # Thomas Nagy, 2005-2018 (ita)
 
 """
 Classes related to the build phase (build, clean, install, step, etc)
 
 The inheritance tree is the following:
 
 """
 
 import os, sys, errno, re, shutil, stat
 try:
 	import cPickle
 except ImportError:
 	import pickle as cPickle
 from waflib import Node, Runner, TaskGen, Utils, ConfigSet, Task, Logs, Options, Context, Errors
 
 CACHE_DIR = 'c4che'
 """Name of the cache directory"""
 
 CACHE_SUFFIX = '_cache.py'
 """ConfigSet cache files for variants are written under :py:attr:´waflib.Build.CACHE_DIR´ in the form ´variant_name´_cache.py"""
 
 INSTALL = 1337
 """Positive value '->' install, see :py:attr:`waflib.Build.BuildContext.is_install`"""
 
 UNINSTALL = -1337
 """Negative value '<-' uninstall, see :py:attr:`waflib.Build.BuildContext.is_install`"""
 
 SAVED_ATTRS = 'root node_sigs task_sigs imp_sigs raw_deps node_deps'.split()
 """Build class members to save between the runs; these should be all dicts
 except for `root` which represents a :py:class:`waflib.Node.Node` instance
 """
 
 CFG_FILES = 'cfg_files'
 """Files from the build directory to hash before starting the build (``config.h`` written during the configuration)"""
 
 POST_AT_ONCE = 0
 """Post mode: all task generators are posted before any task executed"""
 
 POST_LAZY = 1
 """Post mode: post the task generators group after group, the tasks in the next group are created when the tasks in the previous groups are done"""
 
 PROTOCOL = -1
 if sys.platform == 'cli':
 	PROTOCOL = 0
 
 class BuildContext(Context.Context):
 	'''executes the build'''
 
 	cmd = 'build'
 	variant = ''
 
 	def __init__(self, **kw):
 		super(BuildContext, self).__init__(**kw)
 
 		self.is_install = 0
 		"""Non-zero value when installing or uninstalling file"""
 
 		self.top_dir = kw.get('top_dir', Context.top_dir)
 		"""See :py:attr:`waflib.Context.top_dir`; prefer :py:attr:`waflib.Build.BuildContext.srcnode`"""
 
 		self.out_dir = kw.get('out_dir', Context.out_dir)
 		"""See :py:attr:`waflib.Context.out_dir`; prefer :py:attr:`waflib.Build.BuildContext.bldnode`"""
 
 		self.run_dir = kw.get('run_dir', Context.run_dir)
 		"""See :py:attr:`waflib.Context.run_dir`"""
 
 		self.launch_dir = Context.launch_dir
 		"""See :py:attr:`waflib.Context.out_dir`; prefer :py:meth:`waflib.Build.BuildContext.launch_node`"""
 
 		self.post_mode = POST_LAZY
 		"""Whether to post the task generators at once or group-by-group (default is group-by-group)"""
 
 		self.cache_dir = kw.get('cache_dir')
 		if not self.cache_dir:
 			self.cache_dir = os.path.join(self.out_dir, CACHE_DIR)
 
 		self.all_envs = {}
 		"""Map names to :py:class:`waflib.ConfigSet.ConfigSet`, the empty string must map to the default environment"""
 
 		# ======================================= #
 		# cache variables
 
 		self.node_sigs = {}
 		"""Dict mapping build nodes to task identifier (uid), it indicates whether a task created a particular file (persists across builds)"""
 
 		self.task_sigs = {}
 		"""Dict mapping task identifiers (uid) to task signatures (persists across builds)"""
 
 		self.imp_sigs = {}
 		"""Dict mapping task identifiers (uid) to implicit task dependencies used for scanning targets (persists across builds)"""
 
 		self.node_deps = {}
 		"""Dict mapping task identifiers (uid) to node dependencies found by :py:meth:`waflib.Task.Task.scan` (persists across builds)"""
 
 		self.raw_deps = {}
 		"""Dict mapping task identifiers (uid) to custom data returned by :py:meth:`waflib.Task.Task.scan` (persists across builds)"""
 
 		self.task_gen_cache_names = {}
 
 		self.jobs = Options.options.jobs
 		"""Amount of jobs to run in parallel"""
 
 		self.targets = Options.options.targets
 		"""List of targets to build (default: \\*)"""
 
 		self.keep = Options.options.keep
 		"""Whether the build should continue past errors"""
 
 		self.progress_bar = Options.options.progress_bar
 		"""
 		Level of progress status:
 
 		0. normal output
 		1. progress bar
 		2. IDE output
 		3. No output at all
 		"""
 
 		# Manual dependencies.
 		self.deps_man = Utils.defaultdict(list)
 		"""Manual dependencies set by :py:meth:`waflib.Build.BuildContext.add_manual_dependency`"""
 
 		# just the structure here
 		self.current_group = 0
 		"""
 		Current build group
 		"""
 
 		self.groups = []
 		"""
 		List containing lists of task generators
 		"""
 
 		self.group_names = {}
 		"""
 		Map group names to the group lists. See :py:meth:`waflib.Build.BuildContext.add_group`
 		"""
 
 		for v in SAVED_ATTRS:
 			if not hasattr(self, v):
 				setattr(self, v, {})
 
 	def get_variant_dir(self):
 		"""Getter for the variant_dir attribute"""
 		if not self.variant:
 			return self.out_dir
 		return os.path.join(self.out_dir, os.path.normpath(self.variant))
 	variant_dir = property(get_variant_dir, None)
 
 	def __call__(self, *k, **kw):
 		"""
 		Create a task generator and add it to the current build group. The following forms are equivalent::
 
 			def build(bld):
 				tg = bld(a=1, b=2)
 
 			def build(bld):
 				tg = bld()
 				tg.a = 1
 				tg.b = 2
 
 			def build(bld):
 				tg = TaskGen.task_gen(a=1, b=2)
 				bld.add_to_group(tg, None)
 
 		:param group: group name to add the task generator to
 		:type group: string
 		"""
 		kw['bld'] = self
 		ret = TaskGen.task_gen(*k, **kw)
 		self.task_gen_cache_names = {} # reset the cache, each time
 		self.add_to_group(ret, group=kw.get('group'))
 		return ret
 
 	def __copy__(self):
 		"""
 		Build contexts cannot be copied
 
 		:raises: :py:class:`waflib.Errors.WafError`
 		"""
 		raise Errors.WafError('build contexts cannot be copied')
 
 	def load_envs(self):
 		"""
 		The configuration command creates files of the form ``build/c4che/NAMEcache.py``. This method
 		creates a :py:class:`waflib.ConfigSet.ConfigSet` instance for each ``NAME`` by reading those
 		files and stores them in :py:attr:`waflib.Build.BuildContext.allenvs`.
 		"""
 		node = self.root.find_node(self.cache_dir)
 		if not node:
 			raise Errors.WafError('The project was not configured: run "waf configure" first!')
 		lst = node.ant_glob('**/*%s' % CACHE_SUFFIX, quiet=True)
 
 		if not lst:
 			raise Errors.WafError('The cache directory is empty: reconfigure the project')
 
 		for x in lst:
 			name = x.path_from(node).replace(CACHE_SUFFIX, '').replace('\\', '/')
 			env = ConfigSet.ConfigSet(x.abspath())
 			self.all_envs[name] = env
 			for f in env[CFG_FILES]:
 				newnode = self.root.find_resource(f)
 				if not newnode or not newnode.exists():
 					raise Errors.WafError('Missing configuration file %r, reconfigure the project!' % f)
 
 	def init_dirs(self):
 		"""
 		Initialize the project directory and the build directory by creating the nodes
 		:py:attr:`waflib.Build.BuildContext.srcnode` and :py:attr:`waflib.Build.BuildContext.bldnode`
 		corresponding to ``top_dir`` and ``variant_dir`` respectively. The ``bldnode`` directory is
 		created if necessary.
 		"""
 		if not (os.path.isabs(self.top_dir) and os.path.isabs(self.out_dir)):
 			raise Errors.WafError('The project was not configured: run "waf configure" first!')
 
 		self.path = self.srcnode = self.root.find_dir(self.top_dir)
 		self.bldnode = self.root.make_node(self.variant_dir)
 		self.bldnode.mkdir()
 
 	def execute(self):
 		"""
 		Restore data from previous builds and call :py:meth:`waflib.Build.BuildContext.execute_build`.
 		Overrides from :py:func:`waflib.Context.Context.execute`
 		"""
 		self.restore()
 		if not self.all_envs:
 			self.load_envs()
 		self.execute_build()
 
 	def execute_build(self):
 		"""
 		Execute the build by:
 
 		* reading the scripts (see :py:meth:`waflib.Context.Context.recurse`)
 		* calling :py:meth:`waflib.Build.BuildContext.pre_build` to call user build functions
 		* calling :py:meth:`waflib.Build.BuildContext.compile` to process the tasks
 		* calling :py:meth:`waflib.Build.BuildContext.post_build` to call user build functions
 		"""
 
 		Logs.info("Waf: Entering directory `%s'", self.variant_dir)
 		self.recurse([self.run_dir])
 		self.pre_build()
 
 		# display the time elapsed in the progress bar
 		self.timer = Utils.Timer()
 
 		try:
 			self.compile()
 		finally:
 			if self.progress_bar == 1 and sys.stderr.isatty():
 				c = self.producer.processed or 1
 				m = self.progress_line(c, c, Logs.colors.BLUE, Logs.colors.NORMAL)
 				Logs.info(m, extra={'stream': sys.stderr, 'c1': Logs.colors.cursor_off, 'c2' : Logs.colors.cursor_on})
 			Logs.info("Waf: Leaving directory `%s'", self.variant_dir)
 		try:
 			self.producer.bld = None
 			del self.producer
 		except AttributeError:
 			pass
 		self.post_build()
 
 	def restore(self):
 		"""
 		Load data from a previous run, sets the attributes listed in :py:const:`waflib.Build.SAVED_ATTRS`
 		"""
 		try:
 			env = ConfigSet.ConfigSet(os.path.join(self.cache_dir, 'build.config.py'))
 		except EnvironmentError:
 			pass
 		else:
 			if env.version < Context.HEXVERSION:
 				raise Errors.WafError('Project was configured with a different version of Waf, please reconfigure it')
 
 			for t in env.tools:
 				self.setup(**t)
 
 		dbfn = os.path.join(self.variant_dir, Context.DBFILE)
 		try:
 			data = Utils.readf(dbfn, 'rb')
 		except (EnvironmentError, EOFError):
 			# handle missing file/empty file
 			Logs.debug('build: Could not load the build cache %s (missing)', dbfn)
 		else:
 			try:
 				Node.pickle_lock.acquire()
 				Node.Nod3 = self.node_class
 				try:
 					data = cPickle.loads(data)
 				except Exception as e:
 					Logs.debug('build: Could not pickle the build cache %s: %r', dbfn, e)
 				else:
 					for x in SAVED_ATTRS:
 						setattr(self, x, data.get(x, {}))
 			finally:
 				Node.pickle_lock.release()
 
 		self.init_dirs()
 
 	def store(self):
 		"""
 		Store data for next runs, set the attributes listed in :py:const:`waflib.Build.SAVED_ATTRS`. Uses a temporary
 		file to avoid problems on ctrl+c.
 		"""
 		data = {}
 		for x in SAVED_ATTRS:
 			data[x] = getattr(self, x)
 		db = os.path.join(self.variant_dir, Context.DBFILE)
 
 		try:
 			Node.pickle_lock.acquire()
 			Node.Nod3 = self.node_class
 			x = cPickle.dumps(data, PROTOCOL)
 		finally:
 			Node.pickle_lock.release()
 
 		Utils.writef(db + '.tmp', x, m='wb')
 
 		try:
 			st = os.stat(db)
 			os.remove(db)
 			if not Utils.is_win32: # win32 has no chown but we're paranoid
 				os.chown(db + '.tmp', st.st_uid, st.st_gid)
 		except (AttributeError, OSError):
 			pass
 
 		# do not use shutil.move (copy is not thread-safe)
 		os.rename(db + '.tmp', db)
 
 	def compile(self):
 		"""
 		Run the build by creating an instance of :py:class:`waflib.Runner.Parallel`
 		The cache file is written when at least a task was executed.
 
 		:raises: :py:class:`waflib.Errors.BuildError` in case the build fails
 		"""
 		Logs.debug('build: compile()')
 
 		# delegate the producer-consumer logic to another object to reduce the complexity
 		self.producer = Runner.Parallel(self, self.jobs)
 		self.producer.biter = self.get_build_iterator()
 		try:
 			self.producer.start()
 		except KeyboardInterrupt:
 			if self.is_dirty():
 				self.store()
 			raise
 		else:
 			if self.is_dirty():
 				self.store()
 
 		if self.producer.error:
 			raise Errors.BuildError(self.producer.error)
 
 	def is_dirty(self):
 		return self.producer.dirty
 
 	def setup(self, tool, tooldir=None, funs=None):
 		"""
 		Import waf tools defined during the configuration::
 
 			def configure(conf):
 				conf.load('glib2')
 
 			def build(bld):
 				pass # glib2 is imported implicitly
 
 		:param tool: tool list
 		:type tool: list
 		:param tooldir: optional tool directory (sys.path)
 		:type tooldir: list of string
 		:param funs: unused variable
 		"""
 		if isinstance(tool, list):
 			for i in tool:
 				self.setup(i, tooldir)
 			return
 
 		module = Context.load_tool(tool, tooldir)
 		if hasattr(module, "setup"):
 			module.setup(self)
 
 	def get_env(self):
 		"""Getter for the env property"""
 		try:
 			return self.all_envs[self.variant]
 		except KeyError:
 			return self.all_envs['']
 	def set_env(self, val):
 		"""Setter for the env property"""
 		self.all_envs[self.variant] = val
 
 	env = property(get_env, set_env)
 
 	def add_manual_dependency(self, path, value):
 		"""
 		Adds a dependency from a node object to a value::
 
 			def build(bld):
 				bld.add_manual_dependency(
 					bld.path.find_resource('wscript'),
 					bld.root.find_resource('/etc/fstab'))
 
 		:param path: file path
 		:type path: string or :py:class:`waflib.Node.Node`
 		:param value: value to depend
 		:type value: :py:class:`waflib.Node.Node`, byte object, or function returning a byte object
 		"""
 		if not path:
 			raise ValueError('Invalid input path %r' % path)
 
 		if isinstance(path, Node.Node):
 			node = path
 		elif os.path.isabs(path):
 			node = self.root.find_resource(path)
 		else:
 			node = self.path.find_resource(path)
 		if not node:
 			raise ValueError('Could not find the path %r' % path)
 
 		if isinstance(value, list):
 			self.deps_man[node].extend(value)
 		else:
 			self.deps_man[node].append(value)
 
 	def launch_node(self):
 		"""Returns the launch directory as a :py:class:`waflib.Node.Node` object (cached)"""
 		try:
 			# private cache
 			return self.p_ln
 		except AttributeError:
 			self.p_ln = self.root.find_dir(self.launch_dir)
 			return self.p_ln
 
 	def hash_env_vars(self, env, vars_lst):
 		"""
 		Hashes configuration set variables::
 
 			def build(bld):
 				bld.hash_env_vars(bld.env, ['CXX', 'CC'])
 
 		This method uses an internal cache.
 
 		:param env: Configuration Set
 		:type env: :py:class:`waflib.ConfigSet.ConfigSet`
 		:param vars_lst: list of variables
 		:type vars_list: list of string
 		"""
 
 		if not env.table:
 			env = env.parent
 			if not env:
 				return Utils.SIG_NIL
 
 		idx = str(id(env)) + str(vars_lst)
 		try:
 			cache = self.cache_env
 		except AttributeError:
 			cache = self.cache_env = {}
 		else:
 			try:
 				return self.cache_env[idx]
 			except KeyError:
 				pass
 
 		lst = [env[a] for a in vars_lst]
 		cache[idx] = ret = Utils.h_list(lst)
 		Logs.debug('envhash: %s %r', Utils.to_hex(ret), lst)
 		return ret
 
 	def get_tgen_by_name(self, name):
 		"""
 		Fetches a task generator by its name or its target attribute;
 		the name must be unique in a build::
 
 			def build(bld):
 				tg = bld(name='foo')
 				tg == bld.get_tgen_by_name('foo')
 
 		This method use a private internal cache.
 
 		:param name: Task generator name
 		:raises: :py:class:`waflib.Errors.WafError` in case there is no task genenerator by that name
 		"""
 		cache = self.task_gen_cache_names
 		if not cache:
 			# create the index lazily
 			for g in self.groups:
 				for tg in g:
 					try:
 						cache[tg.name] = tg
 					except AttributeError:
 						# raised if not a task generator, which should be uncommon
 						pass
 		try:
 			return cache[name]
 		except KeyError:
 			raise Errors.WafError('Could not find a task generator for the name %r' % name)
 
 	def progress_line(self, idx, total, col1, col2):
 		"""
 		Computes a progress bar line displayed when running ``waf -p``
 
 		:returns: progress bar line
 		:rtype: string
 		"""
 		if not sys.stderr.isatty():
 			return ''
 
 		n = len(str(total))
 
 		Utils.rot_idx += 1
 		ind = Utils.rot_chr[Utils.rot_idx % 4]
 
 		pc = (100. * idx)/total
 		fs = "[%%%dd/%%d][%%s%%2d%%%%%%s][%s][" % (n, ind)
 		left = fs % (idx, total, col1, pc, col2)
 		right = '][%s%s%s]' % (col1, self.timer, col2)
 
 		cols = Logs.get_term_cols() - len(left) - len(right) + 2*len(col1) + 2*len(col2)
 		if cols < 7:
 			cols = 7
 
 		ratio = ((cols * idx)//total) - 1
 
 		bar = ('='*ratio+'>').ljust(cols)
 		msg = Logs.indicator % (left, bar, right)
 
 		return msg
 
 	def declare_chain(self, *k, **kw):
 		"""
 		Wraps :py:func:`waflib.TaskGen.declare_chain` for convenience
 		"""
 		return TaskGen.declare_chain(*k, **kw)
 
 	def pre_build(self):
 		"""Executes user-defined methods before the build starts, see :py:meth:`waflib.Build.BuildContext.add_pre_fun`"""
 		for m in getattr(self, 'pre_funs', []):
 			m(self)
 
 	def post_build(self):
 		"""Executes user-defined methods after the build is successful, see :py:meth:`waflib.Build.BuildContext.add_post_fun`"""
 		for m in getattr(self, 'post_funs', []):
 			m(self)
 
 	def add_pre_fun(self, meth):
 		"""
 		Binds a callback method to execute after the scripts are read and before the build starts::
 
 			def mycallback(bld):
 				print("Hello, world!")
 
 			def build(bld):
 				bld.add_pre_fun(mycallback)
 		"""
 		try:
 			self.pre_funs.append(meth)
 		except AttributeError:
 			self.pre_funs = [meth]
 
 	def add_post_fun(self, meth):
 		"""
 		Binds a callback method to execute immediately after the build is successful::
 
 			def call_ldconfig(bld):
 				bld.exec_command('/sbin/ldconfig')
 
 			def build(bld):
 				if bld.cmd == 'install':
 					bld.add_pre_fun(call_ldconfig)
 		"""
 		try:
 			self.post_funs.append(meth)
 		except AttributeError:
 			self.post_funs = [meth]
 
 	def get_group(self, x):
 		"""
 		Returns the build group named `x`, or the current group if `x` is None
 
 		:param x: name or number or None
 		:type x: string, int or None
 		"""
 		if not self.groups:
 			self.add_group()
 		if x is None:
 			return self.groups[self.current_group]
 		if x in self.group_names:
 			return self.group_names[x]
 		return self.groups[x]
 
 	def add_to_group(self, tgen, group=None):
 		"""Adds a task or a task generator to the build; there is no attempt to remove it if it was already added."""
 		assert(isinstance(tgen, TaskGen.task_gen) or isinstance(tgen, Task.Task))
 		tgen.bld = self
 		self.get_group(group).append(tgen)
 
 	def get_group_name(self, g):
 		"""
 		Returns the name of the input build group
 
 		:param g: build group object or build group index
 		:type g: integer or list
 		:return: name
 		:rtype: string
 		"""
 		if not isinstance(g, list):
 			g = self.groups[g]
 		for x in self.group_names:
 			if id(self.group_names[x]) == id(g):
 				return x
 		return ''
 
 	def get_group_idx(self, tg):
 		"""
 		Returns the index of the group containing the task generator given as argument::
 
 			def build(bld):
 				tg = bld(name='nada')
 				0 == bld.get_group_idx(tg)
 
 		:param tg: Task generator object
 		:type tg: :py:class:`waflib.TaskGen.task_gen`
 		:rtype: int
 		"""
 		se = id(tg)
 		for i, tmp in enumerate(self.groups):
 			for t in tmp:
 				if id(t) == se:
 					return i
 		return None
 
 	def add_group(self, name=None, move=True):
 		"""
 		Adds a new group of tasks/task generators. By default the new group becomes
 		the default group for new task generators (make sure to create build groups in order).
 
 		:param name: name for this group
 		:type name: string
 		:param move: set this new group as default group (True by default)
 		:type move: bool
 		:raises: :py:class:`waflib.Errors.WafError` if a group by the name given already exists
 		"""
 		if name and name in self.group_names:
 			raise Errors.WafError('add_group: name %s already present', name)
 		g = []
 		self.group_names[name] = g
 		self.groups.append(g)
 		if move:
 			self.current_group = len(self.groups) - 1
 
 	def set_group(self, idx):
 		"""
 		Sets the build group at position idx as current so that newly added
 		task generators are added to this one by default::
 
 			def build(bld):
 				bld(rule='touch ${TGT}', target='foo.txt')
 				bld.add_group() # now the current group is 1
 				bld(rule='touch ${TGT}', target='bar.txt')
 				bld.set_group(0) # now the current group is 0
 				bld(rule='touch ${TGT}', target='truc.txt') # build truc.txt before bar.txt
 
 		:param idx: group name or group index
 		:type idx: string or int
 		"""
 		if isinstance(idx, str):
 			g = self.group_names[idx]
 			for i, tmp in enumerate(self.groups):
 				if id(g) == id(tmp):
 					self.current_group = i
 					break
 		else:
 			self.current_group = idx
 
 	def total(self):
 		"""
 		Approximate task count: this value may be inaccurate if task generators
 		are posted lazily (see :py:attr:`waflib.Build.BuildContext.post_mode`).
 		The value :py:attr:`waflib.Runner.Parallel.total` is updated during the task execution.
 
 		:rtype: int
 		"""
 		total = 0
 		for group in self.groups:
 			for tg in group:
 				try:
 					total += len(tg.tasks)
 				except AttributeError:
 					total += 1
 		return total
 
 	def get_targets(self):
 		"""
 		This method returns a pair containing the index of the last build group to post,
 		and the list of task generator objects corresponding to the target names.
 
 		This is used internally by :py:meth:`waflib.Build.BuildContext.get_build_iterator`
 		to perform partial builds::
 
 			$ waf --targets=myprogram,myshlib
 
 		:return: the minimum build group index, and list of task generators
 		:rtype: tuple
 		"""
 		to_post = []
 		min_grp = 0
 		for name in self.targets.split(','):
 			tg = self.get_tgen_by_name(name)
 			m = self.get_group_idx(tg)
 			if m > min_grp:
 				min_grp = m
 				to_post = [tg]
 			elif m == min_grp:
 				to_post.append(tg)
 		return (min_grp, to_post)
 
 	def get_all_task_gen(self):
 		"""
 		Returns a list of all task generators for troubleshooting purposes.
 		"""
 		lst = []
 		for g in self.groups:
 			lst.extend(g)
 		return lst
 
 	def post_group(self):
 		"""
 		Post task generators from the group indexed by self.current_group; used internally
 		by :py:meth:`waflib.Build.BuildContext.get_build_iterator`
 		"""
 		def tgpost(tg):
 			try:
 				f = tg.post
 			except AttributeError:
 				pass
 			else:
 				f()
 
 		if self.targets == '*':
 			for tg in self.groups[self.current_group]:
 				tgpost(tg)
 		elif self.targets:
 			if self.current_group < self._min_grp:
 				for tg in self.groups[self.current_group]:
 					tgpost(tg)
 			else:
 				for tg in self._exact_tg:
 					tg.post()
 		else:
 			ln = self.launch_node()
 			if ln.is_child_of(self.bldnode):
 				if Logs.verbose > 1:
 					Logs.warn('Building from the build directory, forcing --targets=*')
 				ln = self.srcnode
 			elif not ln.is_child_of(self.srcnode):
 				if Logs.verbose > 1:
 					Logs.warn('CWD %s is not under %s, forcing --targets=* (run distclean?)', ln.abspath(), self.srcnode.abspath())
 				ln = self.srcnode
 
 			def is_post(tg, ln):
 				try:
 					p = tg.path
 				except AttributeError:
 					pass
 				else:
 					if p.is_child_of(ln):
 						return True
 
 			def is_post_group():
 				for i, g in enumerate(self.groups):
 					if i > self.current_group:
 						for tg in g:
 							if is_post(tg, ln):
 								return True
 
 			if self.post_mode == POST_LAZY and ln != self.srcnode:
 				# partial folder builds require all targets from a previous build group
 				if is_post_group():
 					ln = self.srcnode
 
 			for tg in self.groups[self.current_group]:
 				if is_post(tg, ln):
 					tgpost(tg)
 
 	def get_tasks_group(self, idx):
 		"""
 		Returns all task instances for the build group at position idx,
 		used internally by :py:meth:`waflib.Build.BuildContext.get_build_iterator`
 
 		:rtype: list of :py:class:`waflib.Task.Task`
 		"""
 		tasks = []
 		for tg in self.groups[idx]:
 			try:
 				tasks.extend(tg.tasks)
 			except AttributeError: # not a task generator
 				tasks.append(tg)
 		return tasks
 
 	def get_build_iterator(self):
 		"""
 		Creates a Python generator object that returns lists of tasks that may be processed in parallel.
 
 		:return: tasks which can be executed immediately
 		:rtype: generator returning lists of :py:class:`waflib.Task.Task`
 		"""
 		if self.targets and self.targets != '*':
 			(self._min_grp, self._exact_tg) = self.get_targets()
 
 		if self.post_mode != POST_LAZY:
 			for self.current_group, _ in enumerate(self.groups):
 				self.post_group()
 
 		for self.current_group, _ in enumerate(self.groups):
 			# first post the task generators for the group
 			if self.post_mode != POST_AT_ONCE:
 				self.post_group()
 
 			# then extract the tasks
 			tasks = self.get_tasks_group(self.current_group)
 
 			# if the constraints are set properly (ext_in/ext_out, before/after)
 			# the call to set_file_constraints may be removed (can be a 15% penalty on no-op rebuilds)
 			# (but leave set_file_constraints for the installation step)
 			#
 			# if the tasks have only files, set_file_constraints is required but set_precedence_constraints is not necessary
 			#
 			Task.set_file_constraints(tasks)
 			Task.set_precedence_constraints(tasks)
 
 			self.cur_tasks = tasks
 			if tasks:
 				yield tasks
 
 		while 1:
 			# the build stops once there are no tasks to process
 			yield []
 
 	def install_files(self, dest, files, **kw):
 		"""
 		Creates a task generator to install files on the system::
 
 			def build(bld):
 				bld.install_files('${DATADIR}', self.path.find_resource('wscript'))
 
 		:param dest: path representing the destination directory
 		:type dest: :py:class:`waflib.Node.Node` or string (absolute path)
 		:param files: input files
 		:type files: list of strings or list of :py:class:`waflib.Node.Node`
 		:param env: configuration set to expand *dest*
 		:type env: :py:class:`waflib.ConfigSet.ConfigSet`
 		:param relative_trick: preserve the folder hierarchy when installing whole folders
 		:type relative_trick: bool
 		:param cwd: parent node for searching srcfile, when srcfile is not an instance of :py:class:`waflib.Node.Node`
 		:type cwd: :py:class:`waflib.Node.Node`
 		:param postpone: execute the task immediately to perform the installation (False by default)
 		:type postpone: bool
 		"""
 		assert(dest)
 		tg = self(features='install_task', install_to=dest, install_from=files, **kw)
 		tg.dest = tg.install_to
 		tg.type = 'install_files'
 		if not kw.get('postpone', True):
 			tg.post()
 		return tg
 
 	def install_as(self, dest, srcfile, **kw):
 		"""
 		Creates a task generator to install a file on the system with a different name::
 
 			def build(bld):
 				bld.install_as('${PREFIX}/bin', 'myapp', chmod=Utils.O755)
 
 		:param dest: destination file
 		:type dest: :py:class:`waflib.Node.Node` or string (absolute path)
 		:param srcfile: input file
 		:type srcfile: string or :py:class:`waflib.Node.Node`
 		:param cwd: parent node for searching srcfile, when srcfile is not an instance of :py:class:`waflib.Node.Node`
 		:type cwd: :py:class:`waflib.Node.Node`
 		:param env: configuration set for performing substitutions in dest
 		:type env: :py:class:`waflib.ConfigSet.ConfigSet`
 		:param postpone: execute the task immediately to perform the installation (False by default)
 		:type postpone: bool
 		"""
 		assert(dest)
 		tg = self(features='install_task', install_to=dest, install_from=srcfile, **kw)
 		tg.dest = tg.install_to
 		tg.type = 'install_as'
 		if not kw.get('postpone', True):
 			tg.post()
 		return tg
 
 	def symlink_as(self, dest, src, **kw):
 		"""
 		Creates a task generator to install a symlink::
 
 			def build(bld):
 				bld.symlink_as('${PREFIX}/lib/libfoo.so', 'libfoo.so.1.2.3')
 
 		:param dest: absolute path of the symlink
 		:type dest: :py:class:`waflib.Node.Node` or string (absolute path)
 		:param src: link contents, which is a relative or absolute path which may exist or not
 		:type src: string
 		:param env: configuration set for performing substitutions in dest
 		:type env: :py:class:`waflib.ConfigSet.ConfigSet`
 		:param add: add the task created to a build group - set ``False`` only if the installation task is created after the build has started
 		:type add: bool
 		:param postpone: execute the task immediately to perform the installation
 		:type postpone: bool
 		:param relative_trick: make the symlink relative (default: ``False``)
 		:type relative_trick: bool
 		"""
 		assert(dest)
 		tg = self(features='install_task', install_to=dest, install_from=src, **kw)
 		tg.dest = tg.install_to
 		tg.type = 'symlink_as'
 		tg.link = src
 		# TODO if add: self.add_to_group(tsk)
 		if not kw.get('postpone', True):
 			tg.post()
 		return tg
 
 @TaskGen.feature('install_task')
 @TaskGen.before_method('process_rule', 'process_source')
 def process_install_task(self):
 	"""Creates the installation task for the current task generator; uses :py:func:`waflib.Build.add_install_task` internally."""
 	self.add_install_task(**self.__dict__)
 
 @TaskGen.taskgen_method
 def add_install_task(self, **kw):
 	"""
 	Creates the installation task for the current task generator, and executes it immediately if necessary
 
 	:returns: An installation task
 	:rtype: :py:class:`waflib.Build.inst`
 	"""
 	if not self.bld.is_install:
 		return
 	if not kw['install_to']:
 		return
 
 	if kw['type'] == 'symlink_as' and Utils.is_win32:
 		if kw.get('win32_install'):
 			kw['type'] = 'install_as'
 		else:
 			# just exit
 			return
 
 	tsk = self.install_task = self.create_task('inst')
 	tsk.chmod = kw.get('chmod', Utils.O644)
 	tsk.link = kw.get('link', '') or kw.get('install_from', '')
 	tsk.relative_trick = kw.get('relative_trick', False)
 	tsk.type = kw['type']
 	tsk.install_to = tsk.dest = kw['install_to']
 	tsk.install_from = kw['install_from']
 	tsk.relative_base = kw.get('cwd') or kw.get('relative_base', self.path)
 	tsk.install_user = kw.get('install_user')
 	tsk.install_group = kw.get('install_group')
 	tsk.init_files()
 	if not kw.get('postpone', True):
 		tsk.run_now()
 	return tsk
 
 @TaskGen.taskgen_method
 def add_install_files(self, **kw):
 	"""
 	Creates an installation task for files
 
 	:returns: An installation task
 	:rtype: :py:class:`waflib.Build.inst`
 	"""
 	kw['type'] = 'install_files'
 	return self.add_install_task(**kw)
 
 @TaskGen.taskgen_method
 def add_install_as(self, **kw):
 	"""
 	Creates an installation task for a single file
 
 	:returns: An installation task
 	:rtype: :py:class:`waflib.Build.inst`
 	"""
 	kw['type'] = 'install_as'
 	return self.add_install_task(**kw)
 
 @TaskGen.taskgen_method
 def add_symlink_as(self, **kw):
 	"""
 	Creates an installation task for a symbolic link
 
 	:returns: An installation task
 	:rtype: :py:class:`waflib.Build.inst`
 	"""
 	kw['type'] = 'symlink_as'
 	return self.add_install_task(**kw)
 
 class inst(Task.Task):
 	"""Task that installs files or symlinks; it is typically executed by :py:class:`waflib.Build.InstallContext` and :py:class:`waflib.Build.UnInstallContext`"""
 	def __str__(self):
 		"""Returns an empty string to disable the standard task display"""
 		return ''
 
 	def uid(self):
 		"""Returns a unique identifier for the task"""
 		lst = self.inputs + self.outputs + [self.link, self.generator.path.abspath()]
 		return Utils.h_list(lst)
 
 	def init_files(self):
 		"""
 		Initializes the task input and output nodes
 		"""
 		if self.type == 'symlink_as':
 			inputs = []
 		else:
 			inputs = self.generator.to_nodes(self.install_from)
 			if self.type == 'install_as':
 				assert len(inputs) == 1
 		self.set_inputs(inputs)
 
 		dest = self.get_install_path()
 		outputs = []
 		if self.type == 'symlink_as':
 			if self.relative_trick:
 				self.link = os.path.relpath(self.link, os.path.dirname(dest))
 			outputs.append(self.generator.bld.root.make_node(dest))
 		elif self.type == 'install_as':
 			outputs.append(self.generator.bld.root.make_node(dest))
 		else:
 			for y in inputs:
 				if self.relative_trick:
 					destfile = os.path.join(dest, y.path_from(self.relative_base))
 				else:
 					destfile = os.path.join(dest, y.name)
 				outputs.append(self.generator.bld.root.make_node(destfile))
 		self.set_outputs(outputs)
 
 	def runnable_status(self):
 		"""
 		Installation tasks are always executed, so this method returns either :py:const:`waflib.Task.ASK_LATER` or :py:const:`waflib.Task.RUN_ME`.
 		"""
 		ret = super(inst, self).runnable_status()
 		if ret == Task.SKIP_ME and self.generator.bld.is_install:
 			return Task.RUN_ME
 		return ret
 
 	def post_run(self):
 		"""
 		Disables any post-run operations
 		"""
 		pass
 
 	def get_install_path(self, destdir=True):
 		"""
 		Returns the destination path where files will be installed, pre-pending `destdir`.
 
 		Relative paths will be interpreted relative to `PREFIX` if no `destdir` is given.
 
 		:rtype: string
 		"""
 		if isinstance(self.install_to, Node.Node):
 			dest = self.install_to.abspath()
 		else:
 			dest = os.path.normpath(Utils.subst_vars(self.install_to, self.env))
 		if not os.path.isabs(dest):
 			dest = os.path.join(self.env.PREFIX, dest)
 		if destdir and Options.options.destdir:
 			dest = Options.options.destdir.rstrip(os.sep) + os.sep + os.path.splitdrive(dest)[1].lstrip(os.sep)
 		return dest
 
 	def copy_fun(self, src, tgt):
 		"""
 		Copies a file from src to tgt, preserving permissions and trying to work
 		around path limitations on Windows platforms. On Unix-like platforms,
 		the owner/group of the target file may be set through install_user/install_group
 
 		:param src: absolute path
 		:type src: string
 		:param tgt: absolute path
 		:type tgt: string
 		"""
 		# override this if you want to strip executables
 		# kw['tsk'].source is the task that created the files in the build
 		if Utils.is_win32 and len(tgt) > 259 and not tgt.startswith('\\\\?\\'):
 			tgt = '\\\\?\\' + tgt
 		shutil.copy2(src, tgt)
 		self.fix_perms(tgt)
 
 	def rm_empty_dirs(self, tgt):
 		"""
 		Removes empty folders recursively when uninstalling.
 
 		:param tgt: absolute path
 		:type tgt: string
 		"""
 		while tgt:
 			tgt = os.path.dirname(tgt)
 			try:
 				os.rmdir(tgt)
 			except OSError:
 				break
 
 	def run(self):
 		"""
 		Performs file or symlink installation
 		"""
 		is_install = self.generator.bld.is_install
 		if not is_install: # unnecessary?
 			return
 
 		for x in self.outputs:
 			if is_install == INSTALL:
 				x.parent.mkdir()
 		if self.type == 'symlink_as':
 			fun = is_install == INSTALL and self.do_link or self.do_unlink
 			fun(self.link, self.outputs[0].abspath())
 		else:
 			fun = is_install == INSTALL and self.do_install or self.do_uninstall
 			launch_node = self.generator.bld.launch_node()
 			for x, y in zip(self.inputs, self.outputs):
 				fun(x.abspath(), y.abspath(), x.path_from(launch_node))
 
 	def run_now(self):
 		"""
 		Try executing the installation task right now
 
 		:raises: :py:class:`waflib.Errors.TaskNotReady`
 		"""
 		status = self.runnable_status()
 		if status not in (Task.RUN_ME, Task.SKIP_ME):
 			raise Errors.TaskNotReady('Could not process %r: status %r' % (self, status))
 		self.run()
 		self.hasrun = Task.SUCCESS
 
 	def do_install(self, src, tgt, lbl, **kw):
 		"""
 		Copies a file from src to tgt with given file permissions. The actual copy is only performed
 		if the source and target file sizes or timestamps differ. When the copy occurs,
 		the file is always first removed and then copied so as to prevent stale inodes.
 
 		:param src: file name as absolute path
 		:type src: string
 		:param tgt: file destination, as absolute path
 		:type tgt: string
 		:param lbl: file source description
 		:type lbl: string
 		:param chmod: installation mode
 		:type chmod: int
 		:raises: :py:class:`waflib.Errors.WafError` if the file cannot be written
 		"""
 		if not Options.options.force:
 			# check if the file is already there to avoid a copy
 			try:
 				st1 = os.stat(tgt)
 				st2 = os.stat(src)
 			except OSError:
 				pass
 			else:
 				# same size and identical timestamps -> make no copy
 				if st1.st_mtime + 2 >= st2.st_mtime and st1.st_size == st2.st_size:
 					if not self.generator.bld.progress_bar:
 
 						c1 = Logs.colors.NORMAL
 						c2 = Logs.colors.BLUE
 
 						Logs.info('%s- install %s%s%s (from %s)', c1, c2, tgt, c1, lbl)
 					return False
 
 		if not self.generator.bld.progress_bar:
 
 			c1 = Logs.colors.NORMAL
 			c2 = Logs.colors.BLUE
 
 			Logs.info('%s+ install %s%s%s (from %s)', c1, c2, tgt, c1, lbl)
 
 		# Give best attempt at making destination overwritable,
 		# like the 'install' utility used by 'make install' does.
 		try:
 			os.chmod(tgt, Utils.O644 | stat.S_IMODE(os.stat(tgt).st_mode))
 		except EnvironmentError:
 			pass
 
 		# following is for shared libs and stale inodes (-_-)
 		try:
 			os.remove(tgt)
 		except OSError:
 			pass
 
 		try:
 			self.copy_fun(src, tgt)
 		except EnvironmentError as e:
 			if not os.path.exists(src):
 				Logs.error('File %r does not exist', src)
 			elif not os.path.isfile(src):
 				Logs.error('Input %r is not a file', src)
 			raise Errors.WafError('Could not install the file %r' % tgt, e)
 
 	def fix_perms(self, tgt):
 		"""
 		Change the ownership of the file/folder/link pointed by the given path
 		This looks up for `install_user` or `install_group` attributes
 		on the task or on the task generator::
 
 			def build(bld):
 				bld.install_as('${PREFIX}/wscript',
 					'wscript',
 					install_user='nobody', install_group='nogroup')
 				bld.symlink_as('${PREFIX}/wscript_link',
 					Utils.subst_vars('${PREFIX}/wscript', bld.env),
 					install_user='nobody', install_group='nogroup')
 		"""
 		if not Utils.is_win32:
 			user = getattr(self, 'install_user', None) or getattr(self.generator, 'install_user', None)
 			group = getattr(self, 'install_group', None) or getattr(self.generator, 'install_group', None)
 			if user or group:
 				Utils.lchown(tgt, user or -1, group or -1)
 		if not os.path.islink(tgt):
 			os.chmod(tgt, self.chmod)
 
 	def do_link(self, src, tgt, **kw):
 		"""
 		Creates a symlink from tgt to src.
 
 		:param src: file name as absolute path
 		:type src: string
 		:param tgt: file destination, as absolute path
 		:type tgt: string
 		"""
 		if os.path.islink(tgt) and os.readlink(tgt) == src:
 			if not self.generator.bld.progress_bar:
 				c1 = Logs.colors.NORMAL
 				c2 = Logs.colors.BLUE
 				Logs.info('%s- symlink %s%s%s (to %s)', c1, c2, tgt, c1, src)
 		else:
 			try:
 				os.remove(tgt)
 			except OSError:
 				pass
 			if not self.generator.bld.progress_bar:
 				c1 = Logs.colors.NORMAL
 				c2 = Logs.colors.BLUE
 				Logs.info('%s+ symlink %s%s%s (to %s)', c1, c2, tgt, c1, src)
 			os.symlink(src, tgt)
 			self.fix_perms(tgt)
 
 	def do_uninstall(self, src, tgt, lbl, **kw):
 		"""
 		See :py:meth:`waflib.Build.inst.do_install`
 		"""
 		if not self.generator.bld.progress_bar:
 			c1 = Logs.colors.NORMAL
 			c2 = Logs.colors.BLUE
 			Logs.info('%s- remove %s%s%s', c1, c2, tgt, c1)
 
 		#self.uninstall.append(tgt)
 		try:
 			os.remove(tgt)
 		except OSError as e:
 			if e.errno != errno.ENOENT:
 				if not getattr(self, 'uninstall_error', None):
 					self.uninstall_error = True
 					Logs.warn('build: some files could not be uninstalled (retry with -vv to list them)')
 				if Logs.verbose > 1:
 					Logs.warn('Could not remove %s (error code %r)', e.filename, e.errno)
 		self.rm_empty_dirs(tgt)
 
 	def do_unlink(self, src, tgt, **kw):
 		"""
 		See :py:meth:`waflib.Build.inst.do_link`
 		"""
 		try:
 			if not self.generator.bld.progress_bar:
 				c1 = Logs.colors.NORMAL
 				c2 = Logs.colors.BLUE
 				Logs.info('%s- remove %s%s%s', c1, c2, tgt, c1)
 			os.remove(tgt)
 		except OSError:
 			pass
 		self.rm_empty_dirs(tgt)
 
 class InstallContext(BuildContext):
 	'''installs the targets on the system'''
 	cmd = 'install'
 
 	def __init__(self, **kw):
 		super(InstallContext, self).__init__(**kw)
 		self.is_install = INSTALL
 
 class UninstallContext(InstallContext):
 	'''removes the targets installed'''
 	cmd = 'uninstall'
 
 	def __init__(self, **kw):
 		super(UninstallContext, self).__init__(**kw)
 		self.is_install = UNINSTALL
 
 class CleanContext(BuildContext):
 	'''cleans the project'''
 	cmd = 'clean'
 	def execute(self):
 		"""
 		See :py:func:`waflib.Build.BuildContext.execute`.
 		"""
 		self.restore()
 		if not self.all_envs:
 			self.load_envs()
 
 		self.recurse([self.run_dir])
 		try:
 			self.clean()
 		finally:
 			self.store()
 
 	def clean(self):
 		"""
 		Remove most files from the build directory, and reset all caches.
 
 		Custom lists of files to clean can be declared as `bld.clean_files`.
 		For example, exclude `build/program/myprogram` from getting removed::
 
 			def build(bld):
 				bld.clean_files = bld.bldnode.ant_glob('**',
 					excl='.lock* config.log c4che/* config.h program/myprogram',
 					quiet=True, generator=True)
 		"""
 		Logs.debug('build: clean called')
 
 		if hasattr(self, 'clean_files'):
 			for n in self.clean_files:
 				n.delete()
 		elif self.bldnode != self.srcnode:
 			# would lead to a disaster if top == out
 			lst = []
 			for env in self.all_envs.values():
 				lst.extend(self.root.find_or_declare(f) for f in env[CFG_FILES])
 			excluded_dirs = '.lock* *conf_check_*/** config.log %s/*' % CACHE_DIR
 			# reverse: ant_globs returns nodes in preorder, but we
 			# need postorder for directory deletion
 			for n in reversed(self.bldnode.ant_glob('**/*', excl=excluded_dirs, quiet=True, dir=True)):
 				if n in lst:
 					continue
 				try:
 					if os.path.isdir(n.abspath()):
 						os.rmdir(n.abspath())
 					else:
 						os.remove(n.abspath())
 				except OSError:
 					pass
 				n.evict()
 		self.root.children = {}
 
 		for v in SAVED_ATTRS:
 			if v == 'root':
 				continue
 			setattr(self, v, {})
 
 class ListContext(BuildContext):
 	'''lists the targets to execute'''
 	cmd = 'list'
 
 	def execute(self):
 		"""
 		In addition to printing the name of each build target,
 		a description column will include text for each task
 		generator which has a "description" field set.
 
 		See :py:func:`waflib.Build.BuildContext.execute`.
 		"""
 		self.restore()
 		if not self.all_envs:
 			self.load_envs()
 
 		self.recurse([self.run_dir])
 		self.pre_build()
 
 		# display the time elapsed in the progress bar
 		self.timer = Utils.Timer()
 
 		for g in self.groups:
 			for tg in g:
 				try:
 					f = tg.post
 				except AttributeError:
 					pass
 				else:
 					f()
 
 		try:
 			# force the cache initialization
 			self.get_tgen_by_name('')
 		except Errors.WafError:
 			pass
 
 		targets = sorted(self.task_gen_cache_names)
 
 		# figure out how much to left-justify, for largest target name
 		line_just = max(len(t) for t in targets) if targets else 0
 
 		for target in targets:
 			tgen = self.task_gen_cache_names[target]
 
 			# Support displaying the description for the target
 			# if it was set on the tgen
 			descript = getattr(tgen, 'description', '')
 			if descript:
 				target = target.ljust(line_just)
 				descript = ': %s' % descript
 
 			Logs.pprint('GREEN', target, label=descript)
 
 class StepContext(BuildContext):
 	'''executes tasks in a step-by-step fashion, for debugging'''
 	cmd = 'step'
 
 	def __init__(self, **kw):
 		super(StepContext, self).__init__(**kw)
 		self.files = Options.options.files
 
 	def compile(self):
 		"""
 		Overrides :py:meth:`waflib.Build.BuildContext.compile` to perform a partial build
 		on tasks matching the input/output pattern given (regular expression matching)::
 
 			$ waf step --files=foo.c,bar.c,in:truc.c,out:bar.o
 			$ waf step --files=in:foo.cpp.1.o # link task only
 
 		"""
 		if not self.files:
 			Logs.warn('Add a pattern for the debug build, for example "waf step --files=main.c,app"')
 			BuildContext.compile(self)
 			return
 
 		targets = []
 		if self.targets and self.targets != '*':
 			targets = self.targets.split(',')
 
 		for g in self.groups:
 			for tg in g:
 				if targets and tg.name not in targets:
 					continue
 
 				try:
 					f = tg.post
 				except AttributeError:
 					pass
 				else:
 					f()
 
 			for pat in self.files.split(','):
 				matcher = self.get_matcher(pat)
 				for tg in g:
 					if isinstance(tg, Task.Task):
 						lst = [tg]
 					else:
 						lst = tg.tasks
 					for tsk in lst:
 						do_exec = False
 						for node in tsk.inputs:
 							if matcher(node, output=False):
 								do_exec = True
 								break
 						for node in tsk.outputs:
 							if matcher(node, output=True):
 								do_exec = True
 								break
 						if do_exec:
 							ret = tsk.run()
 							Logs.info('%s -> exit %r', tsk, ret)
 
 	def get_matcher(self, pat):
 		"""
 		Converts a step pattern into a function
 
 		:param: pat: pattern of the form in:truc.c,out:bar.o
 		:returns: Python function that uses Node objects as inputs and returns matches
 		:rtype: function
 		"""
 		# this returns a function
 		inn = True
 		out = True
 		if pat.startswith('in:'):
 			out = False
 			pat = pat.replace('in:', '')
 		elif pat.startswith('out:'):
 			inn = False
 			pat = pat.replace('out:', '')
 
 		anode = self.root.find_node(pat)
 		pattern = None
 		if not anode:
 			if not pat.startswith('^'):
 				pat = '^.+?%s' % pat
 			if not pat.endswith('$'):
 				pat = '%s$' % pat
 			pattern = re.compile(pat)
 
 		def match(node, output):
 			if output and not out:
 				return False
 			if not output and not inn:
 				return False
 
 			if anode:
 				return anode == node
 			else:
 				return pattern.match(node.abspath())
 		return match
 
 class EnvContext(BuildContext):
 	"""Subclass EnvContext to create commands that require configuration data in 'env'"""
 	fun = cmd = None
 	def execute(self):
 		"""
 		See :py:func:`waflib.Build.BuildContext.execute`.
 		"""
 		self.restore()
 		if not self.all_envs:
 			self.load_envs()
 		self.recurse([self.run_dir])