ironic/ironic/api/functions.py

# Copyright 2011-2019 the WSME authors and contributors
# (See https://opendev.org/x/wsme/)
#
# This module is part of WSME and is also released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.

import functools
import inspect
import logging

log = logging.getLogger(__name__)


def iswsmefunction(f):
    return hasattr(f, '_wsme_definition')


def wrapfunc(f):
    @functools.wraps(f)
    def wrapper(*args, **kwargs):
        return f(*args, **kwargs)
    wrapper._wsme_original_func = f
    return wrapper


def getargspec(f):
    f = getattr(f, '_wsme_original_func', f)
    func_argspec = inspect.getfullargspec(f)
    return func_argspec[0:4]


class FunctionArgument(object):
    """An argument definition of an api entry"""
    def __init__(self, name, datatype, mandatory, default):
        #: argument name
        self.name = name

        #: Data type
        self.datatype = datatype

        #: True if the argument is mandatory
        self.mandatory = mandatory

        #: Default value if argument is omitted
        self.default = default

    def resolve_type(self, registry):
        self.datatype = registry.resolve_type(self.datatype)


class FunctionDefinition(object):
    """An api entry definition"""
    def __init__(self, func):
        #: Function name
        self.name = func.__name__

        #: Function documentation
        self.doc = func.__doc__

        #: Return type
        self.return_type = None

        #: The function arguments (list of :class:`FunctionArgument`)
        self.arguments = []

        #: If the body carry the data of a single argument, its type
        self.body_type = None

        #: Status code
        self.status_code = 200

        #: True if extra arguments should be ignored, NOT inserted in
        #: the kwargs of the function and not raise UnknownArgument
        #: exceptions
        self.ignore_extra_args = False

        #: Dictionary of protocol-specific options.
        self.extra_options = None

    @staticmethod
    def get(func):
        """Returns the :class:`FunctionDefinition` of a method."""
        if not hasattr(func, '_wsme_definition'):
            fd = FunctionDefinition(func)
            func._wsme_definition = fd

        return func._wsme_definition

    def get_arg(self, name):
        """Returns a :class:`FunctionArgument` from its name"""
        for arg in self.arguments:
            if arg.name == name:
                return arg
        return None

    def resolve_types(self, registry):
        self.return_type = registry.resolve_type(self.return_type)
        self.body_type = registry.resolve_type(self.body_type)
        for arg in self.arguments:
            arg.resolve_type(registry)

    def set_options(self, body=None, ignore_extra_args=False, status_code=200,
                    rest_content_types=('json', 'xml'), **extra_options):
        self.body_type = body
        self.status_code = status_code
        self.ignore_extra_args = ignore_extra_args
        self.rest_content_types = rest_content_types
        self.extra_options = extra_options

    def set_arg_types(self, argspec, arg_types):
        args, varargs, keywords, defaults = argspec
        if args[0] == 'self':
            args = args[1:]
        arg_types = list(arg_types)
        if self.body_type is not None:
            arg_types.append(self.body_type)
        for i, argname in enumerate(args):
            datatype = arg_types[i]
            mandatory = defaults is None or i < (len(args) - len(defaults))
            default = None
            if not mandatory:
                default = defaults[i - (len(args) - len(defaults))]
            self.arguments.append(FunctionArgument(argname, datatype,
                                                   mandatory, default))


class signature(object):

    """Decorator that specify the argument types of an exposed function.

    :param return_type: Type of the value returned by the function
    :param argN: Type of the Nth argument
    :param body: If the function takes a final argument that is supposed to be
                 the request body by itself, its type.
    :param status_code: HTTP return status code of the function.
    :param ignore_extra_args: Allow extra/unknown arguments (default to False)

    Most of the time this decorator is not supposed to be used directly,
    unless you are not using WSME on top of another framework.

    If an adapter is used, it will provide either a specialised version of this
    decororator, either a new decorator named @wsexpose that takes the same
    parameters (it will in addition expose the function, hence its name).
    """

    def __init__(self, *types, **options):
        self.return_type = types[0] if types else None
        self.arg_types = []
        if len(types) > 1:
            self.arg_types.extend(types[1:])
        if 'body' in options:
            self.arg_types.append(options['body'])
        self.wrap = options.pop('wrap', False)
        self.options = options

    def __call__(self, func):
        argspec = getargspec(func)
        if self.wrap:
            func = wrapfunc(func)
        fd = FunctionDefinition.get(func)
        if fd.extra_options is not None:
            raise ValueError("This function is already exposed")
        fd.return_type = self.return_type
        fd.set_options(**self.options)
        if self.arg_types:
            fd.set_arg_types(argspec, self.arg_types)
        return func


sig = signature