Add pylint to depot_tools.

third_party/logilab/astng/inference.py

+# copyright 2003-2011 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
+# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr
+# copyright 2003-2010 Sylvain Thenault, all rights reserved.
+# contact mailto:thenault@gmail.com
+#
+# This file is part of logilab-astng.
+#
+# logilab-astng is free software: you can redistribute it and/or modify it
+# under the terms of the GNU Lesser General Public License as published by the
+# Free Software Foundation, either version 2.1 of the License, or (at your
+# option) any later version.
+#
+# logilab-astng is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
+# for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License along
+# with logilab-astng. If not, see <http://www.gnu.org/licenses/>.
+"""this module contains a set of functions to handle inference on astng trees
+"""
+
+__doctype__ = "restructuredtext en"
+
+from itertools import chain
+import sys
+
+from logilab.astng import nodes
+
+from logilab.astng.manager import ASTNGManager
+from logilab.astng.exceptions import (ASTNGBuildingException, ASTNGError,
+    InferenceError, NoDefault, NotFoundError, UnresolvableName)
+from logilab.astng.bases import YES, Instance, InferenceContext, Generator, \
+     _infer_stmts, copy_context, path_wrapper, raise_if_nothing_infered
+from logilab.astng.protocols import _arguments_infer_argname
+
+MANAGER = ASTNGManager()
+
+
+class CallContext:
+    """when inferring a function call, this class is used to remember values
+    given as argument
+    """
+    def __init__(self, args, starargs, dstarargs):
+        self.args = []
+        self.nargs = {}
+        for arg in args:
+            if isinstance(arg, nodes.Keyword):
+                self.nargs[arg.arg] = arg.value
+            else:
+                self.args.append(arg)
+        self.starargs = starargs
+        self.dstarargs = dstarargs
+
+    def infer_argument(self, funcnode, name, context):
+        """infer a function argument value according to the call context"""
+        # 1. search in named keywords
+        try:
+            return self.nargs[name].infer(context)
+        except KeyError:
+            # Function.args.args can be None in astng (means that we don't have
+            # information on argnames)
+            argindex = funcnode.args.find_argname(name)[0]
+            if argindex is not None:
+                # 2. first argument of instance/class method
+                if argindex == 0 and funcnode.type in ('method', 'classmethod'):
+                    if context.boundnode is not None:
+                        boundnode = context.boundnode
+                    else:
+                        # XXX can do better ?
+                        boundnode = funcnode.parent.frame()
+                    if funcnode.type == 'method':
+                        if not isinstance(boundnode, Instance):
+                            boundnode = Instance(boundnode)
+                        return iter((boundnode,))
+                    if funcnode.type == 'classmethod':
+                        return iter((boundnode,))
+                # 2. search arg index
+                try:
+                    return self.args[argindex].infer(context)
+                except IndexError:
+                    pass
+                # 3. search in *args (.starargs)
+                if self.starargs is not None:
+                    its = []
+                    for infered in self.starargs.infer(context):
+                        if infered is YES:
+                            its.append((YES,))
+                            continue
+                        try:
+                            its.append(infered.getitem(argindex, context).infer(context))
+                        except (InferenceError, AttributeError):
+                            its.append((YES,))
+                        except (IndexError, TypeError):
+                            continue
+                    if its:
+                        return chain(*its)
+        # 4. XXX search in **kwargs (.dstarargs)
+        if self.dstarargs is not None:
+            its = []
+            for infered in self.dstarargs.infer(context):
+                if infered is YES:
+                    its.append((YES,))
+                    continue
+                try:
+                    its.append(infered.getitem(name, context).infer(context))
+                except (InferenceError, AttributeError):
+                    its.append((YES,))
+                except (IndexError, TypeError):
+                    continue
+            if its:
+                return chain(*its)
+        # 5. */** argument, (Tuple or Dict)
+        if name == funcnode.args.vararg:
+            return iter((nodes.const_factory(())))
+        if name == funcnode.args.kwarg:
+            return iter((nodes.const_factory({})))
+        # 6. return default value if any
+        try:
+            return funcnode.args.default_value(name).infer(context)
+        except NoDefault:
+            raise InferenceError(name)
+
+
+# .infer method ###############################################################
+
+
+def infer_end(self, context=None):
+    """inference's end for node such as Module, Class, Function, Const...
+    """
+    yield self
+nodes.Module.infer = infer_end
+nodes.Class.infer = infer_end
+nodes.Function.infer = infer_end
+nodes.Lambda.infer = infer_end
+nodes.Const.infer = infer_end
+nodes.List.infer = infer_end
+nodes.Tuple.infer = infer_end
+nodes.Dict.infer = infer_end
+
+
+def infer_name(self, context=None):
+    """infer a Name: use name lookup rules"""
+    frame, stmts = self.lookup(self.name)
+    if not stmts:
+        raise UnresolvableName(self.name)
+    context = context.clone()
+    context.lookupname = self.name
+    return _infer_stmts(stmts, context, frame)
+nodes.Name.infer = path_wrapper(infer_name)
+nodes.AssName.infer_lhs = infer_name # won't work with a path wrapper
+
+
+def infer_callfunc(self, context=None):
+    """infer a CallFunc node by trying to guess what the function returns"""
+    callcontext = context.clone()
+    callcontext.callcontext = CallContext(self.args, self.starargs, self.kwargs)
+    callcontext.boundnode = None
+    for callee in self.func.infer(context):
+        if callee is YES:
+            yield callee
+            continue
+        try:
+            if hasattr(callee, 'infer_call_result'):
+                for infered in callee.infer_call_result(self, callcontext):
+                    yield infered
+        except InferenceError:
+            ## XXX log error ?
+            continue
+nodes.CallFunc.infer = path_wrapper(raise_if_nothing_infered(infer_callfunc))
+
+
+def infer_import(self, context=None, asname=True):
+    """infer an Import node: return the imported module/object"""
+    name = context.lookupname
+    if name is None:
+        raise InferenceError()
+    if asname:
+        yield self.do_import_module(self.real_name(name))
+    else:
+        yield self.do_import_module(name)
+nodes.Import.infer = path_wrapper(infer_import)
+
+def infer_name_module(self, name):
+    context = InferenceContext()
+    context.lookupname = name
+    return self.infer(context, asname=False)
+nodes.Import.infer_name_module = infer_name_module
+
+
+def infer_from(self, context=None, asname=True):
+    """infer a From nodes: return the imported module/object"""
+    name = context.lookupname
+    if name is None:
+        raise InferenceError()
+    if asname:
+        name = self.real_name(name)
+    module = self.do_import_module(self.modname)
+    try:
+        context = copy_context(context)
+        context.lookupname = name
+        return _infer_stmts(module.getattr(name, ignore_locals=module is self.root()), context)
+    except NotFoundError:
+        raise InferenceError(name)
+nodes.From.infer = path_wrapper(infer_from)
+
+
+def infer_getattr(self, context=None):
+    """infer a Getattr node by using getattr on the associated object"""
+    #context = context.clone()
+    for owner in self.expr.infer(context):
+        if owner is YES:
+            yield owner
+            continue
+        try:
+            context.boundnode = owner
+            for obj in owner.igetattr(self.attrname, context):
+                yield obj
+            context.boundnode = None
+        except (NotFoundError, InferenceError):
+            context.boundnode = None
+        except AttributeError:
+            # XXX method / function
+            context.boundnode = None
+nodes.Getattr.infer = path_wrapper(raise_if_nothing_infered(infer_getattr))
+nodes.AssAttr.infer_lhs = raise_if_nothing_infered(infer_getattr) # # won't work with a path wrapper
+
+
+def infer_global(self, context=None):
+    if context.lookupname is None:
+        raise InferenceError()
+    try:
+        return _infer_stmts(self.root().getattr(context.lookupname), context)
+    except NotFoundError:
+        raise InferenceError()
+nodes.Global.infer = path_wrapper(infer_global)
+
+
+def infer_subscript(self, context=None):
+    """infer simple subscription such as [1,2,3][0] or (1,2,3)[-1]"""
+    if isinstance(self.slice, nodes.Index):
+        index = self.slice.value.infer(context).next()
+        if index is YES:
+            yield YES
+            return
+        try:
+            # suppose it's a Tuple/List node (attribute error else)
+            assigned = self.value.getitem(index.value, context)
+        except AttributeError:
+            raise InferenceError()
+        except (IndexError, TypeError):
+            yield YES
+            return
+        for infered in assigned.infer(context):
+            yield infered
+    else:
+        raise InferenceError()
+nodes.Subscript.infer = path_wrapper(infer_subscript)
+nodes.Subscript.infer_lhs = raise_if_nothing_infered(infer_subscript)
+
+
+UNARY_OP_METHOD = {'+': '__pos__',
+                   '-': '__neg__',
+                   '~': '__invert__',
+                   'not': None, # XXX not '__nonzero__'
+                  }
+
+def infer_unaryop(self, context=None):
+    for operand in self.operand.infer(context):
+        try:
+            yield operand.infer_unary_op(self.op)
+        except TypeError:
+            continue
+        except AttributeError:
+            meth = UNARY_OP_METHOD[self.op]
+            if meth is None:
+                yield YES
+            else:
+                try:
+                    # XXX just suppose if the type implement meth, returned type
+                    # will be the same
+                    operand.getattr(meth)
+                    yield operand
+                except GeneratorExit:
+                    raise
+                except:
+                    yield YES
+nodes.UnaryOp.infer = path_wrapper(infer_unaryop)
+
+
+BIN_OP_METHOD = {'+':  '__add__',
+                 '-':  '__sub__',
+                 '/':  '__div__',
+                 '//': '__floordiv__',
+                 '*':  '__mul__',
+                 '**': '__power__',
+                 '%':  '__mod__',
+                 '&':  '__and__',
+                 '|':  '__or__',
+                 '^':  '__xor__',
+                 '<<': '__lshift__',
+                 '>>': '__rshift__',
+                 }
+
+def _infer_binop(operator, operand1, operand2, context, failures=None):
+    if operand1 is YES:
+        yield operand1
+        return
+    try:
+        for valnode in operand1.infer_binary_op(operator, operand2, context):
+            yield valnode
+    except AttributeError:
+        try:
+            # XXX just suppose if the type implement meth, returned type
+            # will be the same
+            operand1.getattr(BIN_OP_METHOD[operator])
+            yield operand1
+        except:
+            if failures is None:
+                yield YES
+            else:
+                failures.append(operand1)
+
+def infer_binop(self, context=None):
+    failures = []
+    for lhs in self.left.infer(context):
+        for val in _infer_binop(self.op, lhs, self.right, context, failures):
+            yield val
+    for lhs in failures:
+        for rhs in self.right.infer(context):
+            for val in _infer_binop(self.op, rhs, lhs, context):
+                yield val
+nodes.BinOp.infer = path_wrapper(infer_binop)
+
+
+def infer_arguments(self, context=None):
+    name = context.lookupname
+    if name is None:
+        raise InferenceError()
+    return _arguments_infer_argname(self, name, context)
+nodes.Arguments.infer = infer_arguments
+
+
+def infer_ass(self, context=None):
+    """infer a AssName/AssAttr: need to inspect the RHS part of the
+    assign node
+    """
+    stmt = self.statement()
+    if isinstance(stmt, nodes.AugAssign):
+        return stmt.infer(context)
+    stmts = list(self.assigned_stmts(context=context))
+    return _infer_stmts(stmts, context)
+nodes.AssName.infer = path_wrapper(infer_ass)
+nodes.AssAttr.infer = path_wrapper(infer_ass)
+
+def infer_augassign(self, context=None):
+    failures = []
+    for lhs in self.target.infer_lhs(context):
+        for val in _infer_binop(self.op, lhs, self.value, context, failures):
+            yield val
+    for lhs in failures:
+        for rhs in self.value.infer(context):
+            for val in _infer_binop(self.op, rhs, lhs, context):
+                yield val
+nodes.AugAssign.infer = path_wrapper(infer_augassign)
+
+
+# no infer method on DelName and DelAttr (expected InferenceError)
+
+
+def infer_empty_node(self, context=None):
+    if not self.has_underlying_object():
+        yield YES
+    else:
+        try:
+            for infered in MANAGER.infer_astng_from_something(self.object,
+                                                              context=context):
+                yield infered
+        except ASTNGError:
+            yield YES
+nodes.EmptyNode.infer = path_wrapper(infer_empty_node)
+