pylint: upgrade to 1.4.1

third_party/logilab/astroid/brain/builtin_inference.py

+"""Astroid hooks for various builtins."""
+
+import sys
+from functools import partial
+from textwrap import dedent
+
+import six
+from astroid import (MANAGER, UseInferenceDefault,
+                     inference_tip, YES, InferenceError, UnresolvableName)
+from astroid import nodes
+from astroid.builder import AstroidBuilder
+
+
+def _extend_str(class_node, rvalue):
+    """function to extend builtin str/unicode class"""
+    # TODO(cpopa): this approach will make astroid to believe
+    # that some arguments can be passed by keyword, but
+    # unfortunately, strings and bytes don't accept keyword arguments.
+    code = dedent('''
+    class whatever(object):
+        def join(self, iterable):
+            return {rvalue}
+        def replace(self, old, new, count=None):
+            return {rvalue}
+        def format(self, *args, **kwargs):
+            return {rvalue}
+        def encode(self, encoding='ascii', errors=None):
+            return ''
+        def decode(self, encoding='ascii', errors=None):
+            return u''
+        def capitalize(self):
+            return {rvalue}
+        def title(self):
+            return {rvalue}
+        def lower(self):
+            return {rvalue}
+        def upper(self):
+            return {rvalue}
+        def swapcase(self):
+            return {rvalue}
+        def index(self, sub, start=None, end=None):
+            return 0
+        def find(self, sub, start=None, end=None):
+            return 0
+        def count(self, sub, start=None, end=None):
+            return 0
+        def strip(self, chars=None):
+            return {rvalue}
+        def lstrip(self, chars=None):
+            return {rvalue}
+        def rstrip(self, chars=None):
+            return {rvalue}
+        def rjust(self, width, fillchar=None):
+            return {rvalue} 
+        def center(self, width, fillchar=None):
+            return {rvalue}
+        def ljust(self, width, fillchar=None):
+            return {rvalue}
+    ''')
+    code = code.format(rvalue=rvalue)
+    fake = AstroidBuilder(MANAGER).string_build(code)['whatever']
+    for method in fake.mymethods():
+        class_node.locals[method.name] = [method]
+        method.parent = class_node
+
+def extend_builtins(class_transforms):
+    from astroid.bases import BUILTINS
+    builtin_ast = MANAGER.astroid_cache[BUILTINS]
+    for class_name, transform in class_transforms.items():
+        transform(builtin_ast[class_name])
+
+if sys.version_info > (3, 0):
+    extend_builtins({'bytes': partial(_extend_str, rvalue="b''"),
+                     'str': partial(_extend_str, rvalue="''")})
+else:
+    extend_builtins({'str': partial(_extend_str, rvalue="''"),
+                     'unicode': partial(_extend_str, rvalue="u''")})
+
+
+def register_builtin_transform(transform, builtin_name):
+    """Register a new transform function for the given *builtin_name*.
+
+    The transform function must accept two parameters, a node and
+    an optional context.
+    """
+    def _transform_wrapper(node, context=None):
+        result = transform(node, context=context)
+        if result:
+            result.parent = node
+            result.lineno = node.lineno
+            result.col_offset = node.col_offset
+        return iter([result])
+
+    MANAGER.register_transform(nodes.CallFunc,
+                               inference_tip(_transform_wrapper),
+                               lambda n: (isinstance(n.func, nodes.Name) and
+                                          n.func.name == builtin_name))
+
+
+def _generic_inference(node, context, node_type, transform):
+    args = node.args
+    if not args:
+        return node_type()
+    if len(node.args) > 1:
+        raise UseInferenceDefault()
+
+    arg, = args
+    transformed = transform(arg)
+    if not transformed:
+        try:
+            infered = next(arg.infer(context=context))
+        except (InferenceError, StopIteration):
+            raise UseInferenceDefault()
+        if infered is YES:
+            raise UseInferenceDefault()
+        transformed = transform(infered)
+    if not transformed or transformed is YES:
+        raise UseInferenceDefault()
+    return transformed
+
+
+def _generic_transform(arg, klass, iterables, build_elts):
+    if isinstance(arg, klass):
+        return arg
+    elif isinstance(arg, iterables):
+        if not all(isinstance(elt, nodes.Const)
+                   for elt in arg.elts):
+            # TODO(cpopa): Don't support heterogenous elements.
+            # Not yet, though.
+            raise UseInferenceDefault()
+        elts = [elt.value for elt in arg.elts]
+    elif isinstance(arg, nodes.Dict):
+        if not all(isinstance(elt[0], nodes.Const)
+                   for elt in arg.items):
+            raise UseInferenceDefault()
+        elts = [item[0].value for item in arg.items]
+    elif (isinstance(arg, nodes.Const) and
+          isinstance(arg.value, (six.string_types, six.binary_type))):
+        elts = arg.value
+    else:
+        return
+    return klass(elts=build_elts(elts))
+
+
+def _infer_builtin(node, context,
+                   klass=None, iterables=None,
+                   build_elts=None):
+    transform_func = partial(
+        _generic_transform,
+        klass=klass,
+        iterables=iterables,
+        build_elts=build_elts)
+
+    return _generic_inference(node, context, klass, transform_func)
+
+# pylint: disable=invalid-name
+infer_tuple = partial(
+    _infer_builtin,
+    klass=nodes.Tuple,
+    iterables=(nodes.List, nodes.Set),
+    build_elts=tuple)
+
+infer_list = partial(
+    _infer_builtin,
+    klass=nodes.List,
+    iterables=(nodes.Tuple, nodes.Set),
+    build_elts=list)
+
+infer_set = partial(
+    _infer_builtin,
+    klass=nodes.Set,
+    iterables=(nodes.List, nodes.Tuple),
+    build_elts=set)
+
+
+def _get_elts(arg, context):
+    is_iterable = lambda n: isinstance(n,
+                                       (nodes.List, nodes.Tuple, nodes.Set))
+    try:
+        infered = next(arg.infer(context))
+    except (InferenceError, UnresolvableName):
+        raise UseInferenceDefault()
+    if isinstance(infered, nodes.Dict):
+        items = infered.items
+    elif is_iterable(infered):
+        items = []
+        for elt in infered.elts:
+            # If an item is not a pair of two items,
+            # then fallback to the default inference.
+            # Also, take in consideration only hashable items,
+            # tuples and consts. We are choosing Names as well.
+            if not is_iterable(elt):
+                raise UseInferenceDefault()
+            if len(elt.elts) != 2:
+                raise UseInferenceDefault()
+            if not isinstance(elt.elts[0],
+                              (nodes.Tuple, nodes.Const, nodes.Name)):
+                raise UseInferenceDefault()
+            items.append(tuple(elt.elts))
+    else:
+        raise UseInferenceDefault()
+    return items
+
+def infer_dict(node, context=None):
+    """Try to infer a dict call to a Dict node.
+
+    The function treats the following cases:
+
+        * dict()
+        * dict(mapping)
+        * dict(iterable)
+        * dict(iterable, **kwargs)
+        * dict(mapping, **kwargs)
+        * dict(**kwargs)
+
+    If a case can't be infered, we'll fallback to default inference.
+    """
+    has_keywords = lambda args: all(isinstance(arg, nodes.Keyword)
+                                    for arg in args)
+    if not node.args and not node.kwargs:
+        # dict()
+        return nodes.Dict()
+    elif has_keywords(node.args) and node.args:
+        # dict(a=1, b=2, c=4)
+        items = [(nodes.Const(arg.arg), arg.value) for arg in node.args]
+    elif (len(node.args) >= 2 and
+          has_keywords(node.args[1:])):
+        # dict(some_iterable, b=2, c=4)
+        elts = _get_elts(node.args[0], context)
+        keys = [(nodes.Const(arg.arg), arg.value) for arg in node.args[1:]]
+        items = elts + keys
+    elif len(node.args) == 1:
+        items = _get_elts(node.args[0], context)
+    else:
+        raise UseInferenceDefault()
+
+    empty = nodes.Dict()
+    empty.items = items
+    return empty
+
+# Builtins inference
+register_builtin_transform(infer_tuple, 'tuple')
+register_builtin_transform(infer_set, 'set')
+register_builtin_transform(infer_list, 'list')
+register_builtin_transform(infer_dict, 'dict')