"""Utility functions, node construction macros, etc.""" # Author: Collin Winter # Local imports from .pgen2 import token from .pytree import Leaf, Node from .pygram import python_symbols as syms from . import patcomp ########################################################### ### Common node-construction "macros" ########################################################### def KeywordArg(keyword, value): return Node(syms.argument, [keyword, Leaf(token.EQUAL, u'='), value]) def LParen(): return Leaf(token.LPAR, u"(") def RParen(): return Leaf(token.RPAR, u")") def Assign(target, source): """Build an assignment statement""" if not isinstance(target, list): target = [target] if not isinstance(source, list): source.prefix = u" " source = [source] return Node(syms.atom, target + [Leaf(token.EQUAL, u"=", prefix=u" ")] + source) def Name(name, prefix=None): """Return a NAME leaf""" return Leaf(token.NAME, name, prefix=prefix) def Attr(obj, attr): """A node tuple for obj.attr""" return [obj, Node(syms.trailer, [Dot(), attr])] def Comma(): """A comma leaf""" return Leaf(token.COMMA, u",") def Dot(): """A period (.) leaf""" return Leaf(token.DOT, u".") def ArgList(args, lparen=LParen(), rparen=RParen()): """A parenthesised argument list, used by Call()""" node = Node(syms.trailer, [lparen.clone(), rparen.clone()]) if args: node.insert_child(1, Node(syms.arglist, args)) return node def Call(func_name, args=None, prefix=None): """A function call""" node = Node(syms.power, [func_name, ArgList(args)]) if prefix is not None: node.prefix = prefix return node def Newline(): """A newline literal""" return Leaf(token.NEWLINE, u"\n") def BlankLine(): """A blank line""" return Leaf(token.NEWLINE, u"") def Number(n, prefix=None): return Leaf(token.NUMBER, n, prefix=prefix) def Subscript(index_node): """A numeric or string subscript""" return Node(syms.trailer, [Leaf(token.LBRACE, u'['), index_node, Leaf(token.RBRACE, u']')]) def String(string, prefix=None): """A string leaf""" return Leaf(token.STRING, string, prefix=prefix) def ListComp(xp, fp, it, test=None): """A list comprehension of the form [xp for fp in it if test]. If test is None, the "if test" part is omitted. """ xp.prefix = u"" fp.prefix = u" " it.prefix = u" " for_leaf = Leaf(token.NAME, u"for") for_leaf.prefix = u" " in_leaf = Leaf(token.NAME, u"in") in_leaf.prefix = u" " inner_args = [for_leaf, fp, in_leaf, it] if test: test.prefix = u" " if_leaf = Leaf(token.NAME, u"if") if_leaf.prefix = u" " inner_args.append(Node(syms.comp_if, [if_leaf, test])) inner = Node(syms.listmaker, [xp, Node(syms.comp_for, inner_args)]) return Node(syms.atom, [Leaf(token.LBRACE, u"["), inner, Leaf(token.RBRACE, u"]")]) def FromImport(package_name, name_leafs): """ Return an import statement in the form: from package import name_leafs""" # XXX: May not handle dotted imports properly (eg, package_name='foo.bar') #assert package_name == '.' or '.' not in package_name, "FromImport has "\ # "not been tested with dotted package names -- use at your own "\ # "peril!" for leaf in name_leafs: # Pull the leaves out of their old tree leaf.remove() children = [Leaf(token.NAME, u'from'), Leaf(token.NAME, package_name, prefix=u" "), Leaf(token.NAME, u'import', prefix=u" "), Node(syms.import_as_names, name_leafs)] imp = Node(syms.import_from, children) return imp ########################################################### ### Determine whether a node represents a given literal ########################################################### def is_tuple(node): """Does the node represent a tuple literal?""" if isinstance(node, Node) and node.children == [LParen(), RParen()]: return True return (isinstance(node, Node) and len(node.children) == 3 and isinstance(node.children[0], Leaf) and isinstance(node.children[1], Node) and isinstance(node.children[2], Leaf) and node.children[0].value == u"(" and node.children[2].value == u")") def is_list(node): """Does the node represent a list literal?""" return (isinstance(node, Node) and len(node.children) > 1 and isinstance(node.children[0], Leaf) and isinstance(node.children[-1], Leaf) and node.children[0].value == u"[" and node.children[-1].value == u"]") ########################################################### ### Misc ########################################################### def parenthesize(node): return Node(syms.atom, [LParen(), node, RParen()]) consuming_calls = set(["sorted", "list", "set", "any", "all", "tuple", "sum", "min", "max"]) def attr_chain(obj, attr): """Follow an attribute chain. If you have a chain of objects where a.foo -> b, b.foo-> c, etc, use this to iterate over all objects in the chain. Iteration is terminated by getattr(x, attr) is None. Args: obj: the starting object attr: the name of the chaining attribute Yields: Each successive object in the chain. """ next = getattr(obj, attr) while next: yield next next = getattr(next, attr) p0 = """for_stmt< 'for' any 'in' node=any ':' any* > | comp_for< 'for' any 'in' node=any any* > """ p1 = """ power< ( 'iter' | 'list' | 'tuple' | 'sorted' | 'set' | 'sum' | 'any' | 'all' | (any* trailer< '.' 'join' >) ) trailer< '(' node=any ')' > any* > """ p2 = """ power< 'sorted' trailer< '(' arglist ')' > any* > """ pats_built = False def in_special_context(node): """ Returns true if node is in an environment where all that is required of it is being itterable (ie, it doesn't matter if it returns a list or an itterator). See test_map_nochange in test_fixers.py for some examples and tests. """ global p0, p1, p2, pats_built if not pats_built: p1 = patcomp.compile_pattern(p1) p0 = patcomp.compile_pattern(p0) p2 = patcomp.compile_pattern(p2) pats_built = True patterns = [p0, p1, p2] for pattern, parent in zip(patterns, attr_chain(node, "parent")): results = {} if pattern.match(parent, results) and results["node"] is node: return True return False def is_probably_builtin(node): """ Check that something isn't an attribute or function name etc. """ prev = node.prev_sibling if prev is not None and prev.type == token.DOT: # Attribute lookup. return False parent = node.parent if parent.type in (syms.funcdef, syms.classdef): return False if parent.type == syms.expr_stmt and parent.children[0] is node: # Assignment. return False if parent.type == syms.parameters or \ (parent.type == syms.typedargslist and ( (prev is not None and prev.type == token.COMMA) or parent.children[0] is node )): # The name of an argument. return False return True ########################################################### ### The following functions are to find bindings in a suite ########################################################### def make_suite(node): if node.type == syms.suite: return node node = node.clone() parent, node.parent = node.parent, None suite = Node(syms.suite, [node]) suite.parent = parent return suite def find_root(node): """Find the top level namespace.""" # Scamper up to the top level namespace while node.type != syms.file_input: assert node.parent, "Tree is insane! root found before "\ "file_input node was found." node = node.parent return node def does_tree_import(package, name, node): """ Returns true if name is imported from package at the top level of the tree which node belongs to. To cover the case of an import like 'import foo', use None for the package and 'foo' for the name. """ binding = find_binding(name, find_root(node), package) return bool(binding) def is_import(node): """Returns true if the node is an import statement.""" return node.type in (syms.import_name, syms.import_from) def touch_import(package, name, node): """ Works like `does_tree_import` but adds an import statement if it was not imported. """ def is_import_stmt(node): return node.type == syms.simple_stmt and node.children and \ is_import(node.children[0]) root = find_root(node) if does_tree_import(package, name, root): return # figure out where to insert the new import. First try to find # the first import and then skip to the last one. insert_pos = offset = 0 for idx, node in enumerate(root.children): if not is_import_stmt(node): continue for offset, node2 in enumerate(root.children[idx:]): if not is_import_stmt(node2): break insert_pos = idx + offset break # if there are no imports where we can insert, find the docstring. # if that also fails, we stick to the beginning of the file if insert_pos == 0: for idx, node in enumerate(root.children): if node.type == syms.simple_stmt and node.children and \ node.children[0].type == token.STRING: insert_pos = idx + 1 break if package is None: import_ = Node(syms.import_name, [ Leaf(token.NAME, u'import'), Leaf(token.NAME, name, prefix=u' ') ]) else: import_ = FromImport(package, [Leaf(token.NAME, name, prefix=u' ')]) children = [import_, Newline()] root.insert_child(insert_pos, Node(syms.simple_stmt, children)) _def_syms = set([syms.classdef, syms.funcdef]) def find_binding(name, node, package=None): """ Returns the node which binds variable name, otherwise None. If optional argument package is supplied, only imports will be returned. See test cases for examples.""" for child in node.children: ret = None if child.type == syms.for_stmt: if _find(name, child.children[1]): return child n = find_binding(name, make_suite(child.children[-1]), package) if n: ret = n elif child.type in (syms.if_stmt, syms.while_stmt): n = find_binding(name, make_suite(child.children[-1]), package) if n: ret = n elif child.type == syms.try_stmt: n = find_binding(name, make_suite(child.children[2]), package) if n: ret = n else: for i, kid in enumerate(child.children[3:]): if kid.type == token.COLON and kid.value == ":": # i+3 is the colon, i+4 is the suite n = find_binding(name, make_suite(child.children[i+4]), package) if n: ret = n elif child.type in _def_syms and child.children[1].value == name: ret = child elif _is_import_binding(child, name, package): ret = child elif child.type == syms.simple_stmt: ret = find_binding(name, child, package) elif child.type == syms.expr_stmt: if _find(name, child.children[0]): ret = child if ret: if not package: return ret if is_import(ret): return ret return None _block_syms = set([syms.funcdef, syms.classdef, syms.trailer]) def _find(name, node): nodes = [node] while nodes: node = nodes.pop() if node.type > 256 and node.type not in _block_syms: nodes.extend(node.children) elif node.type == token.NAME and node.value == name: return node return None def _is_import_binding(node, name, package=None): """ Will reuturn node if node will import name, or node will import * from package. None is returned otherwise. See test cases for examples. """ if node.type == syms.import_name and not package: imp = node.children[1] if imp.type == syms.dotted_as_names: for child in imp.children: if child.type == syms.dotted_as_name: if child.children[2].value == name: return node elif child.type == token.NAME and child.value == name: return node elif imp.type == syms.dotted_as_name: last = imp.children[-1] if last.type == token.NAME and last.value == name: return node elif imp.type == token.NAME and imp.value == name: return node elif node.type == syms.import_from: # unicode(...) is used to make life easier here, because # from a.b import parses to ['import', ['a', '.', 'b'], ...] if package and unicode(node.children[1]).strip() != package: return None n = node.children[3] if package and _find(u'as', n): # See test_from_import_as for explanation return None elif n.type == syms.import_as_names and _find(name, n): return node elif n.type == syms.import_as_name: child = n.children[2] if child.type == token.NAME and child.value == name: return node elif n.type == token.NAME and n.value == name: return node elif package and n.type == token.STAR: return node return None