Merge pyextra subtree

pyextra/jsonrpc/utils.py

@@ -0,0 +1,135 @@
+""" Utility functions for package."""
+from abc import ABCMeta, abstractmethod
+import datetime
+import decimal
+import inspect
+import json
+import sys
+
+from . import six
+
+
+class JSONSerializable(six.with_metaclass(ABCMeta, object)):
+
+    """ Common functionality for json serializable objects."""
+
+    serialize = staticmethod(json.dumps)
+    deserialize = staticmethod(json.loads)
+
+    @abstractmethod
+    def json(self):
+        raise NotImplementedError()
+
+    @classmethod
+    def from_json(cls, json_str):
+        data = cls.deserialize(json_str)
+
+        if not isinstance(data, dict):
+            raise ValueError("data should be dict")
+
+        return cls(**data)
+
+
+class DatetimeDecimalEncoder(json.JSONEncoder):
+
+    """ Encoder for datetime and decimal serialization.
+
+    Usage: json.dumps(object, cls=DatetimeDecimalEncoder)
+    NOTE: _iterencode does not work
+
+    """
+
+    def default(self, o):
+        """ Encode JSON.
+
+        :return str: A JSON encoded string
+
+        """
+        if isinstance(o, decimal.Decimal):
+            return float(o)
+
+        if isinstance(o, (datetime.datetime, datetime.date)):
+            return o.isoformat()
+
+        return json.JSONEncoder.default(self, o)
+
+
+def is_invalid_params_py2(func, *args, **kwargs):
+    """ Check, whether function 'func' accepts parameters 'args', 'kwargs'.
+
+    NOTE: Method is called after funct(*args, **kwargs) generated TypeError,
+    it is aimed to destinguish TypeError because of invalid parameters from
+    TypeError from inside the function.
+
+    .. versionadded: 1.9.0
+
+    """
+    funcargs, varargs, varkwargs, defaults = inspect.getargspec(func)
+
+    unexpected = set(kwargs.keys()) - set(funcargs)
+    if len(unexpected) > 0:
+        return True
+
+    params = [funcarg for funcarg in funcargs if funcarg not in kwargs]
+    funcargs_required = funcargs[:-len(defaults)] \
+        if defaults is not None \
+        else funcargs
+    params_required = [
+        funcarg for funcarg in funcargs_required
+        if funcarg not in kwargs
+    ]
+
+    return not (len(params_required) <= len(args) <= len(params))
+
+
+def is_invalid_params_py3(func, *args, **kwargs):
+    """
+    Use inspect.signature instead of inspect.getargspec or
+    inspect.getfullargspec (based on inspect.signature itself) as it provides
+    more information about function parameters.
+
+    .. versionadded: 1.11.2
+
+    """
+    signature = inspect.signature(func)
+    parameters = signature.parameters
+
+    unexpected = set(kwargs.keys()) - set(parameters.keys())
+    if len(unexpected) > 0:
+        return True
+
+    params = [
+        parameter for name, parameter in parameters.items()
+        if name not in kwargs
+    ]
+    params_required = [
+        param for param in params
+        if param.default is param.empty
+    ]
+
+    return not (len(params_required) <= len(args) <= len(params))
+
+
+def is_invalid_params(func, *args, **kwargs):
+    """
+    Method:
+        Validate pre-defined criteria, if any is True - function is invalid
+        0. func should be callable
+        1. kwargs should not have unexpected keywords
+        2. remove kwargs.keys from func.parameters
+        3. number of args should be <= remaining func.parameters
+        4. number of args should be >= remaining func.parameters less default
+    """
+    # For builtin functions inspect.getargspec(funct) return error. If builtin
+    # function generates TypeError, it is because of wrong parameters.
+    if not inspect.isfunction(func):
+        return True
+
+    if sys.version_info >= (3, 3):
+        return is_invalid_params_py3(func, *args, **kwargs)
+    else:
+        # NOTE: use Python2 method for Python 3.2 as well. Starting from Python
+        # 3.3 it is recommended to use inspect.signature instead.
+        # In Python 3.0 - 3.2 inspect.getfullargspec is preferred but these
+        # versions are almost not supported. Users should consider upgrading.
+        return is_invalid_params_py2(func, *args, **kwargs)