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#

#

# Copyright (C) 2010, 2011 Google Inc.

#

# This program is free software; you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation; either version 2 of the License, or

# (at your option) any later version.

#

# This program 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

# General Public License for more details.

#

# You should have received a copy of the GNU General Public License

# along with this program; if not, write to the Free Software

# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

# 02110-1301, USA.

"""Module implementing the parameter types code."""

import re

from ganeti import compat

from ganeti import utils

_PAREN_RE = re.compile("^[a-zA-Z0-9_-]+$")

def Parens(text):

  """Enclose text in parens if necessary.

  @param text: Text

  """

  text = str(text)

  if _PAREN_RE.match(text):

    return text

  else:

    return "(%s)" % text

def WithDesc(text):

  """Builds wrapper class with description text.

  @type text: string

  @param text: Description text

  @return: Callable class

  """

  assert text[0] == text[0].upper()

  class wrapper(object): # pylint: disable-msg=C0103

    __slots__ = ["__call__"]

    def __init__(self, fn):

      """Initializes this class.

      @param fn: Wrapped function

      """

      self.__call__ = fn

    def __str__(self):

      return text

  return wrapper

def CombinationDesc(op, args, fn):

  """Build description for combinating operator.

  @type op: string

  @param op: Operator as text (e.g. "and")

  @type args: list

  @param args: Operator arguments

  @type fn: callable

  @param fn: Wrapped function

  """

  if len(args) == 1:

    descr = str(args[0])

  else:

    descr = (" %s " % op).join(Parens(i) for i in args)

  return WithDesc(descr)(fn)

# Modifiable default values; need to define these here before the

# actual LUs

@WithDesc(str([]))

def EmptyList():

  """Returns an empty list.

  """

  return []

@WithDesc(str({}))

def EmptyDict():

  """Returns an empty dict.

  """

  return {}

#: The without-default default value

NoDefault = object()

#: The no-type (value too complex to check it in the type system)

NoType = object()

# Some basic types

@WithDesc("NotNone")

def TNotNone(val):

  """Checks if the given value is not None.

  """

  return val is not None

@WithDesc("None")

def TNone(val):

  """Checks if the given value is None.

  """

  return val is None

@WithDesc("Boolean")

def TBool(val):

  """Checks if the given value is a boolean.

  """

  return isinstance(val, bool)

@WithDesc("Integer")

def TInt(val):

  """Checks if the given value is an integer.

  """

  # For backwards compatibility with older Python versions, boolean values are

  # also integers and should be excluded in this test.

  #

  # >>> (isinstance(False, int), isinstance(True, int))

  # (True, True)

  return isinstance(val, int) and not isinstance(val, bool)

@WithDesc("Float")

def TFloat(val):

  """Checks if the given value is a float.

  """

  return isinstance(val, float)

@WithDesc("String")

def TString(val):

  """Checks if the given value is a string.

  """

  return isinstance(val, basestring)

@WithDesc("EvalToTrue")

def TTrue(val):

  """Checks if a given value evaluates to a boolean True value.

  """

  return bool(val)

def TElemOf(target_list):

  """Builds a function that checks if a given value is a member of a list.

  """

  def fn(val):

    return val in target_list

  return WithDesc("OneOf %s" % (utils.CommaJoin(target_list), ))(fn)

# Container types

@WithDesc("List")

def TList(val):

  """Checks if the given value is a list.

  """

  return isinstance(val, list)

@WithDesc("Dictionary")

def TDict(val):

  """Checks if the given value is a dictionary.

  """

  return isinstance(val, dict)

def TIsLength(size):

  """Check is the given container is of the given size.

  """

  def fn(container):

    return len(container) == size

  return WithDesc("Length %s" % (size, ))(fn)

# Combinator types

def TAnd(*args):

  """Combine multiple functions using an AND operation.

  """

  def fn(val):

    return compat.all(t(val) for t in args)

  return CombinationDesc("and", args, fn)

def TOr(*args):

  """Combine multiple functions using an AND operation.

  """

  def fn(val):

    return compat.any(t(val) for t in args)

  return CombinationDesc("or", args, fn)

def TMap(fn, test):

  """Checks that a modified version of the argument passes the given test.

  """

  return WithDesc("Result of %s must be %s" %

                  (Parens(fn), Parens(test)))(lambda val: test(fn(val)))

# Type aliases

#: a non-empty string

TNonEmptyString = WithDesc("NonEmptyString")(TAnd(TString, TTrue))

#: a maybe non-empty string

TMaybeString = TOr(TNonEmptyString, TNone)

#: a maybe boolean (bool or none)

TMaybeBool = TOr(TBool, TNone)

#: Maybe a dictionary (dict or None)

TMaybeDict = TOr(TDict, TNone)

#: a positive integer

TPositiveInt = \

  TAnd(TInt, WithDesc("EqualGreaterZero")(lambda v: v >= 0))

#: a strictly positive integer

TStrictPositiveInt = \

  TAnd(TInt, WithDesc("GreaterThanZero")(lambda v: v > 0))

def TListOf(my_type):

  """Checks if a given value is a list with all elements of the same type.

  """

  desc = WithDesc("List of %s" % (Parens(my_type), ))

  return desc(TAnd(TList, lambda lst: compat.all(my_type(v) for v in lst)))

def TDictOf(key_type, val_type):

  """Checks a dict type for the type of its key/values.

  """

  desc = WithDesc("Dictionary with keys of %s and values of %s" %

                  (Parens(key_type), Parens(val_type)))

  def fn(container):

    return (compat.all(key_type(v) for v in container.keys()) and

            compat.all(val_type(v) for v in container.values()))

  return desc(TAnd(TDict, fn))