Source code for waflib.TaskGen

#!/usr/bin/env python
# encoding: utf-8
# Thomas Nagy, 2005-2018 (ita)

Task generators

The class :py:class:`waflib.TaskGen.task_gen` encapsulates the creation of task objects (low-level code)
The instances can have various parameters, but the creation of task nodes (
is deferred. To achieve this, various methods are called from the method "apply"

import copy, re, os, functools
from waflib import Task, Utils, Logs, Errors, ConfigSet, Node

feats = Utils.defaultdict(set)
"""remember the methods declaring features"""

HEADER_EXTS = ['.h', '.hpp', '.hxx', '.hh']

[docs]class task_gen(object): """ Instances of this class create :py:class:`waflib.Task.Task` when calling the method :py:meth:`` from the main thread. A few notes: * The methods to call (*self.meths*) can be specified dynamically (removing, adding, ..) * The 'features' are used to add methods to self.meths and then execute them * The attribute 'path' is a node representing the location of the task generator * The tasks created are added to the attribute *tasks* * The attribute 'idx' is a counter of task generators in the same path """ mappings = Utils.ordered_iter_dict() """Mappings are global file extension mappings that are retrieved in the order of definition""" prec = Utils.defaultdict(set) """Dict that holds the precedence execution rules for task generator methods"""
[docs] def __init__(self, *k, **kw): """ Task generator objects predefine various attributes (source, target) for possible processing by process_rule (make-like rules) or process_source (extensions, misc methods) Tasks are stored on the attribute 'tasks'. They are created by calling methods listed in ``self.meths`` or referenced in the attribute ``features`` A topological sort is performed to execute the methods in correct order. The extra key/value elements passed in ``kw`` are set as attributes """ self.source = [] = '' self.meths = [] """ List of method names to execute (internal) """ self.features = [] """ List of feature names for bringing new methods in """ self.tasks = [] """ Tasks created are added to this list """ if not 'bld' in kw: # task generators without a build context :-/ self.env = ConfigSet.ConfigSet() self.idx = 0 self.path = None else: self.bld = kw['bld'] self.env = self.bld.env.derive() self.path = kw.get('path', self.bld.path) # by default, emulate chdir when reading scripts # Provide a unique index per folder # This is part of a measure to prevent output file name collisions path = self.path.abspath() try: self.idx = self.bld.idx[path] = self.bld.idx.get(path, 0) + 1 except AttributeError: self.bld.idx = {} self.idx = self.bld.idx[path] = 1 # Record the global task generator count try: self.tg_idx_count = self.bld.tg_idx_count = self.bld.tg_idx_count + 1 except AttributeError: self.tg_idx_count = self.bld.tg_idx_count = 1 for key, val in kw.items(): setattr(self, key, val)
[docs] def __str__(self): """Debugging helper""" return "<task_gen %r declared in %s>" % (, self.path.abspath())
[docs] def __repr__(self): """Debugging helper""" lst = [] for x in self.__dict__: if x not in ('env', 'bld', 'compiled_tasks', 'tasks'): lst.append("%s=%s" % (x, repr(getattr(self, x)))) return "bld(%s) in %s" % (", ".join(lst), self.path.abspath())
[docs] def get_cwd(self): """ Current working directory for the task generator, defaults to the build directory. This is still used in a few places but it should disappear at some point as the classes define their own working directory. :rtype: :py:class:`waflib.Node.Node` """ return self.bld.bldnode
[docs] def get_name(self): """ If the attribute ``name`` is not set on the instance, the name is computed from the target name:: def build(bld): x = bld(name='foo') x.get_name() # foo y = bld(target='bar') y.get_name() # bar :rtype: string :return: name of this task generator """ try: return self._name except AttributeError: if isinstance(, list): lst = [str(x) for x in] name = self._name = ','.join(lst) else: name = self._name = str( return name
def set_name(self, name): self._name = name name = property(get_name, set_name)
[docs] def to_list(self, val): """ Ensures that a parameter is a list, see :py:func:`waflib.Utils.to_list` :type val: string or list of string :param val: input to return as a list :rtype: list """ if isinstance(val, str): return val.split() else: return val
[docs] def post(self): """ Creates tasks for this task generators. The following operations are performed: #. The body of this method is called only once and sets the attribute ``posted`` #. The attribute ``features`` is used to add more methods in ``self.meths`` #. The methods are sorted by the precedence table ``self.prec`` or `:waflib:attr:waflib.TaskGen.task_gen.prec` #. The methods are then executed in order #. The tasks created are added to :py:attr:`waflib.TaskGen.task_gen.tasks` """ if getattr(self, 'posted', None): return False self.posted = True keys = set(self.meths) keys.update(feats['*']) # add the methods listed in the features self.features = Utils.to_list(self.features) for x in self.features: st = feats[x] if st: keys.update(st) elif not x in Task.classes: Logs.warn('feature %r does not exist - bind at least one method to it?', x) # copy the precedence table prec = {} prec_tbl = self.prec for x in prec_tbl: if x in keys: prec[x] = prec_tbl[x] # elements disconnected tmp = [] for a in keys: for x in prec.values(): if a in x: break else: tmp.append(a) tmp.sort(reverse=True) # topological sort out = [] while tmp: e = tmp.pop() if e in keys: out.append(e) try: nlst = prec[e] except KeyError: pass else: del prec[e] for x in nlst: for y in prec: if x in prec[y]: break else: tmp.append(x) tmp.sort(reverse=True) if prec: buf = ['Cycle detected in the method execution:'] for k, v in prec.items(): buf.append('- %s after %s' % (k, [x for x in v if x in prec])) raise Errors.WafError('\n'.join(buf)) self.meths = out # then we run the methods in order Logs.debug('task_gen: posting %s %d', self, id(self)) for x in out: try: v = getattr(self, x) except AttributeError: raise Errors.WafError('%r is not a valid task generator method' % x) Logs.debug('task_gen: -> %s (%d)', x, id(self)) v() Logs.debug('task_gen: posted %s', return True
[docs] def get_hook(self, node): """ Returns the ``@extension`` method to call for a Node of a particular extension. :param node: Input file to process :type node: :py:class:`waflib.Tools.Node.Node` :return: A method able to process the input node by looking at the extension :rtype: function """ name = for k in self.mappings: try: if name.endswith(k): return self.mappings[k] except TypeError: # regexps objects if k.match(name): return self.mappings[k] keys = list(self.mappings.keys()) raise Errors.WafError("File %r has no mapping in %r (load a waf tool?)" % (node, keys))
[docs] def create_task(self, name, src=None, tgt=None, **kw): """ Creates task instances. :param name: task class name :type name: string :param src: input nodes :type src: list of :py:class:`waflib.Tools.Node.Node` :param tgt: output nodes :type tgt: list of :py:class:`waflib.Tools.Node.Node` :return: A task object :rtype: :py:class:`waflib.Task.Task` """ task = Task.classes[name](env=self.env.derive(), generator=self) if src: task.set_inputs(src) if tgt: task.set_outputs(tgt) task.__dict__.update(kw) self.tasks.append(task) return task
[docs] def clone(self, env): """ Makes a copy of a task generator. Once the copy is made, it is necessary to ensure that the it does not create the same output files as the original, or the same files may be compiled several times. :param env: A configuration set :type env: :py:class:`waflib.ConfigSet.ConfigSet` :return: A copy :rtype: :py:class:`waflib.TaskGen.task_gen` """ newobj = self.bld() for x in self.__dict__: if x in ('env', 'bld'): continue elif x in ('path', 'features'): setattr(newobj, x, getattr(self, x)) else: setattr(newobj, x, copy.copy(getattr(self, x))) newobj.posted = False if isinstance(env, str): newobj.env = self.bld.all_envs[env].derive() else: newobj.env = env.derive() return newobj
[docs]def declare_chain(name='', rule=None, reentrant=None, color='BLUE', ext_in=[], ext_out=[], before=[], after=[], decider=None, scan=None, install_path=None, shell=False): """ Creates a new mapping and a task class for processing files by extension. See Tools/ for an example. :param name: name for the task class :type name: string :param rule: function to execute or string to be compiled in a function :type rule: string or function :param reentrant: re-inject the output file in the process (done automatically, set to 0 to disable) :type reentrant: int :param color: color for the task output :type color: string :param ext_in: execute the task only after the files of such extensions are created :type ext_in: list of string :param ext_out: execute the task only before files of such extensions are processed :type ext_out: list of string :param before: execute instances of this task before classes of the given names :type before: list of string :param after: execute instances of this task after classes of the given names :type after: list of string :param decider: if present, function that returns a list of output file extensions (overrides ext_out for output files, but not for the build order) :type decider: function :param scan: scanner function for the task :type scan: function :param install_path: installation path for the output nodes :type install_path: string """ ext_in = Utils.to_list(ext_in) ext_out = Utils.to_list(ext_out) if not name: name = rule cls = Task.task_factory(name, rule, color=color, ext_in=ext_in, ext_out=ext_out, before=before, after=after, scan=scan, shell=shell) def x_file(self, node): if ext_in: _ext_in = ext_in[0] tsk = self.create_task(name, node) cnt = 0 ext = decider(self, node) if decider else cls.ext_out for x in ext: k = node.change_ext(x, ext_in=_ext_in) tsk.outputs.append(k) if reentrant != None: if cnt < int(reentrant): self.source.append(k) else: # reinject downstream files into the build for y in self.mappings: # ~ nfile * nextensions :-/ if self.source.append(k) break cnt += 1 if install_path: self.install_task = self.add_install_files(install_to=install_path, install_from=tsk.outputs) return tsk for x in cls.ext_in: task_gen.mappings[x] = x_file return x_file
def taskgen_method(func): """ Decorator that registers method as a task generator method. The function must accept a task generator as first parameter:: from waflib.TaskGen import taskgen_method @taskgen_method def mymethod(self): pass :param func: task generator method to add :type func: function :rtype: function """ setattr(task_gen, func.__name__, func) return func def feature(*k): """ Decorator that registers a task generator method that will be executed when the object attribute ``feature`` contains the corresponding key(s):: from waflib.Task import feature @feature('myfeature') def myfunction(self): print('that is my feature!') def build(bld): bld(features='myfeature') :param k: feature names :type k: list of string """ def deco(func): setattr(task_gen, func.__name__, func) for name in k: feats[name].update([func.__name__]) return func return deco
[docs]def before_method(*k): """ Decorator that registera task generator method which will be executed before the functions of given name(s):: from waflib.TaskGen import feature, before @feature('myfeature') @before_method('fun2') def fun1(self): print('feature 1!') @feature('myfeature') def fun2(self): print('feature 2!') def build(bld): bld(features='myfeature') :param k: method names :type k: list of string """ def deco(func): setattr(task_gen, func.__name__, func) for fun_name in k: task_gen.prec[func.__name__].add(fun_name) return func return deco
before = before_method
[docs]def after_method(*k): """ Decorator that registers a task generator method which will be executed after the functions of given name(s):: from waflib.TaskGen import feature, after @feature('myfeature') @after_method('fun2') def fun1(self): print('feature 1!') @feature('myfeature') def fun2(self): print('feature 2!') def build(bld): bld(features='myfeature') :param k: method names :type k: list of string """ def deco(func): setattr(task_gen, func.__name__, func) for fun_name in k: task_gen.prec[fun_name].add(func.__name__) return func return deco
after = after_method def extension(*k): """ Decorator that registers a task generator method which will be invoked during the processing of source files for the extension given:: from waflib import Task class mytask(Task): run_str = 'cp ${SRC} ${TGT}' @extension('.moo') def create_maa_file(self, node): self.create_task('mytask', node, node.change_ext('.maa')) def build(bld): bld(source='foo.moo') """ def deco(func): setattr(task_gen, func.__name__, func) for x in k: task_gen.mappings[x] = func return func return deco
[docs]@taskgen_method def to_nodes(self, lst, path=None): """ Flatten the input list of string/nodes/lists into a list of nodes. It is used by :py:func:`waflib.TaskGen.process_source` and :py:func:`waflib.TaskGen.process_rule`. It is designed for source files, for folders, see :py:func:`waflib.Tools.ccroot.to_incnodes`: :param lst: input list :type lst: list of string and nodes :param path: path from which to search the nodes (by default, :py:attr:`waflib.TaskGen.task_gen.path`) :type path: :py:class:`waflib.Tools.Node.Node` :rtype: list of :py:class:`waflib.Tools.Node.Node` """ tmp = [] path = path or self.path find = path.find_resource if isinstance(lst, Node.Node): lst = [lst] for x in Utils.to_list(lst): if isinstance(x, str): node = find(x) elif hasattr(x, 'name'): node = x else: tmp.extend(self.to_nodes(x)) continue if not node: raise Errors.WafError('source not found: %r in %r' % (x, self)) tmp.append(node) return tmp
[docs]@feature('*') def process_source(self): """ Processes each element in the attribute ``source`` by extension. #. The *source* list is converted through :py:meth:`waflib.TaskGen.to_nodes` to a list of :py:class:`waflib.Node.Node` first. #. File extensions are mapped to methods having the signature: ``def meth(self, node)`` by :py:meth:`waflib.TaskGen.extension` #. The method is retrieved through :py:meth:`waflib.TaskGen.task_gen.get_hook` #. When called, the methods may modify self.source to append more source to process #. The mappings can map an extension or a filename (see the code below) """ self.source = self.to_nodes(getattr(self, 'source', [])) for node in self.source: self.get_hook(node)(self, node)
[docs]@feature('*') @before_method('process_source') def process_rule(self): """ Processes the attribute ``rule``. When present, :py:meth:`waflib.TaskGen.process_source` is disabled:: def build(bld): bld(rule='cp ${SRC} ${TGT}', source='wscript', target='bar.txt') Main attributes processed: * rule: command to execute, it can be a tuple of strings for multiple commands * chmod: permissions for the resulting files (integer value such as Utils.O755) * shell: set to False to execute the command directly (default is True to use a shell) * scan: scanner function * vars: list of variables to trigger rebuilds, such as CFLAGS * cls_str: string to display when executing the task * cls_keyword: label to display when executing the task * cache_rule: by default, try to re-use similar classes, set to False to disable * source: list of Node or string objects representing the source files required by this task * target: list of Node or string objects representing the files that this task creates * cwd: current working directory (Node or string) * stdout: standard output, set to None to prevent waf from capturing the text * stderr: standard error, set to None to prevent waf from capturing the text * timeout: timeout for command execution (Python 3) * always: whether to always run the command (False by default) * deep_inputs: whether the task must depend on the input file tasks too (False by default) """ if not getattr(self, 'rule', None): return # create the task class name = str(getattr(self, 'name', None) or or getattr(self.rule, '__name__', self.rule)) # or we can put the class in a cache for performance reasons try: cache = self.bld.cache_rule_attr except AttributeError: cache = self.bld.cache_rule_attr = {} chmod = getattr(self, 'chmod', None) shell = getattr(self, 'shell', True) color = getattr(self, 'color', 'BLUE') scan = getattr(self, 'scan', None) _vars = getattr(self, 'vars', []) cls_str = getattr(self, 'cls_str', None) cls_keyword = getattr(self, 'cls_keyword', None) use_cache = getattr(self, 'cache_rule', 'True') deep_inputs = getattr(self, 'deep_inputs', False) scan_val = has_deps = hasattr(self, 'deps') if scan: scan_val = id(scan) key = Utils.h_list((name, self.rule, chmod, shell, color, cls_str, cls_keyword, scan_val, _vars, deep_inputs)) cls = None if use_cache: try: cls = cache[key] except KeyError: pass if not cls: rule = self.rule if chmod is not None: def chmod_fun(tsk): for x in tsk.outputs: os.chmod(x.abspath(), tsk.generator.chmod) if isinstance(rule, tuple): rule = list(rule) rule.append(chmod_fun) rule = tuple(rule) else: rule = (rule, chmod_fun) cls = Task.task_factory(name, rule, _vars, shell=shell, color=color) if cls_str: setattr(cls, '__str__', self.cls_str) if cls_keyword: setattr(cls, 'keyword', self.cls_keyword) if deep_inputs: Task.deep_inputs(cls) if scan: cls.scan = self.scan elif has_deps: def scan(self): nodes = [] for x in self.generator.to_list(getattr(self.generator, 'deps', None)): node = self.generator.path.find_resource(x) if not node: self.generator.bld.fatal('Could not find %r (was it declared?)' % x) nodes.append(node) return [nodes, []] cls.scan = scan if use_cache: cache[key] = cls # now create one instance tsk = self.create_task(name) for x in ('after', 'before', 'ext_in', 'ext_out'): setattr(tsk, x, getattr(self, x, [])) if hasattr(self, 'stdout'): tsk.stdout = self.stdout if hasattr(self, 'stderr'): tsk.stderr = self.stderr if getattr(self, 'timeout', None): tsk.timeout = self.timeout if getattr(self, 'always', None): tsk.always_run = True if getattr(self, 'target', None): if isinstance(, str): = if not isinstance(, list): = [] for x in if isinstance(x, str): tsk.outputs.append(self.path.find_or_declare(x)) else: x.parent.mkdir() # if a node was given, create the required folders tsk.outputs.append(x) if getattr(self, 'install_path', None): self.install_task = self.add_install_files(install_to=self.install_path, install_from=tsk.outputs, chmod=getattr(self, 'chmod', Utils.O644)) if getattr(self, 'source', None): tsk.inputs = self.to_nodes(self.source) # bypass the execution of process_source by setting the source to an empty list self.source = [] if getattr(self, 'cwd', None): tsk.cwd = self.cwd if isinstance(, functools.partial): # Python documentation says: "partial objects defined in classes # behave like static methods and do not transform into bound # methods during instance attribute look-up." = functools.partial(, tsk)
[docs]@feature('seq') def sequence_order(self): """ Adds a strict sequential constraint between the tasks generated by task generators. It works because task generators are posted in order. It will not post objects which belong to other folders. Example:: bld(features='javac seq') bld(features='jar seq') To start a new sequence, set the attribute seq_start, for example:: obj = bld(features='seq') obj.seq_start = True Note that the method is executed in last position. This is more an example than a widely-used solution. """ if self.meths and self.meths[-1] != 'sequence_order': self.meths.append('sequence_order') return if getattr(self, 'seq_start', None): return # all the tasks previously declared must be run before these if getattr(self.bld, 'prev', None): for x in self.bld.prev.tasks: for y in self.tasks: y.set_run_after(x) self.bld.prev = self
re_m4 = re.compile(r'@(\w+)@', re.M)
[docs]class subst_pc(Task.Task): """ Creates *.pc* files from **. The task is executed whenever an input variable used in the substitution changes. """
[docs] def force_permissions(self): "Private for the time being, we will probably refactor this into run_str=[run1,chmod]" if getattr(self.generator, 'chmod', None): for x in self.outputs: os.chmod(x.abspath(), self.generator.chmod)
[docs] def run(self): "Substitutes variables in a .in file" if getattr(self.generator, 'is_copy', None): for i, x in enumerate(self.outputs): x.write(self.inputs[i].read('rb'), 'wb') stat = os.stat(self.inputs[i].abspath()) # Preserve mtime of the copy os.utime(self.outputs[i].abspath(), (stat.st_atime, stat.st_mtime)) self.force_permissions() return None if getattr(self.generator, 'fun', None): ret = if not ret: self.force_permissions() return ret code = self.inputs[0].read(encoding=getattr(self.generator, 'encoding', 'latin-1')) if getattr(self.generator, 'subst_fun', None): code = self.generator.subst_fun(self, code) if code is not None: self.outputs[0].write(code, encoding=getattr(self.generator, 'encoding', 'latin-1')) self.force_permissions() return None # replace all % by %% to prevent errors by % signs code = code.replace('%', '%%') # extract the vars foo into lst and replace @foo@ by %(foo)s lst = [] def repl(match): g = if g(1): lst.append(g(1)) return "%%(%s)s" % g(1) return '' code = getattr(self.generator, 're_m4', re_m4).sub(repl, code) try: d = self.generator.dct except AttributeError: d = {} for x in lst: tmp = getattr(self.generator, x, '') or self.env[x] or self.env[x.upper()] try: tmp = ''.join(tmp) except TypeError: tmp = str(tmp) d[x] = tmp code = code % d self.outputs[0].write(code, encoding=getattr(self.generator, 'encoding', 'latin-1')) self.generator.bld.raw_deps[self.uid()] = lst # make sure the signature is updated try: delattr(self, 'cache_sig') except AttributeError: pass self.force_permissions()
[docs] def sig_vars(self): """ Compute a hash (signature) of the variables used in the substitution """ bld = self.generator.bld env = self.env upd = self.m.update if getattr(self.generator, 'fun', None): upd(Utils.h_fun( if getattr(self.generator, 'subst_fun', None): upd(Utils.h_fun(self.generator.subst_fun).encode()) # raw_deps: persistent custom values returned by the scanner vars = self.generator.bld.raw_deps.get(self.uid(), []) # hash both env vars and task generator attributes act_sig = bld.hash_env_vars(env, vars) upd(act_sig) lst = [getattr(self.generator, x, '') for x in vars] upd(Utils.h_list(lst)) return self.m.digest()
[docs]@extension('') def add_pcfile(self, node): """ Processes ** files to *.pc*. Installs the results to ``${PREFIX}/lib/pkgconfig/`` by default def build(bld): bld(source='', install_path='${LIBDIR}/pkgconfig/') """ tsk = self.create_task('subst_pc', node, node.change_ext('.pc', '')) self.install_task = self.add_install_files( install_to=getattr(self, 'install_path', '${LIBDIR}/pkgconfig/'), install_from=tsk.outputs)
class subst(subst_pc): pass
[docs]@feature('subst') @before_method('process_source', 'process_rule') def process_subst(self): """ Defines a transformation that substitutes the contents of *source* files to *target* files:: def build(bld): bld( features='subst', source='', target='foo.c', install_path='${LIBDIR}/pkgconfig', VAR = 'val' ) The input files are supposed to contain macros of the form *@VAR@*, where *VAR* is an argument of the task generator object. This method overrides the processing by :py:meth:`waflib.TaskGen.process_source`. """ src = Utils.to_list(getattr(self, 'source', [])) if isinstance(src, Node.Node): src = [src] tgt = Utils.to_list(getattr(self, 'target', [])) if isinstance(tgt, Node.Node): tgt = [tgt] if len(src) != len(tgt): raise Errors.WafError('invalid number of source/target for %r' % self) for x, y in zip(src, tgt): if not x or not y: raise Errors.WafError('null source or target for %r' % self) a, b = None, None if isinstance(x, str) and isinstance(y, str) and x == y: a = self.path.find_node(x) b = self.path.get_bld().make_node(y) if not os.path.isfile(b.abspath()): b.parent.mkdir() else: if isinstance(x, str): a = self.path.find_resource(x) elif isinstance(x, Node.Node): a = x if isinstance(y, str): b = self.path.find_or_declare(y) elif isinstance(y, Node.Node): b = y if not a: raise Errors.WafError('could not find %r for %r' % (x, self)) tsk = self.create_task('subst', a, b) for k in ('after', 'before', 'ext_in', 'ext_out'): val = getattr(self, k, None) if val: setattr(tsk, k, val) # paranoid safety measure for the general case>foo.h with ambiguous dependencies for xt in HEADER_EXTS: if tsk.ext_in = tsk.ext_in + ['.h'] break inst_to = getattr(self, 'install_path', None) if inst_to: self.install_task = self.add_install_files(install_to=inst_to, install_from=b, chmod=getattr(self, 'chmod', Utils.O644)) self.source = []