ansible/lib/ansible/module_utils/_text.py

# This code is part of Ansible, but is an independent component.
# This particular file snippet, and this file snippet only, is BSD licensed.
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# still belong to the author of the module, and may assign their own license
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# Copyright (c), Toshio Kuratomi <a.badger@gmail.com>, 2016
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"""
.. warn:: This module_util is currently internal implementation.
    We want to evaluate this code for stability and API suitability before
    making backwards compatibility guarantees.  The API may change between
    releases.  Do not use this unless you are willing to port your module code.
"""
import codecs

from ansible.module_utils.six import PY3, text_type, binary_type


try:
    codecs.lookup_error('surrogateescape')
    HAS_SURROGATEESCAPE = True
except LookupError:
    HAS_SURROGATEESCAPE = False


def to_bytes(obj, encoding='utf-8', errors=None, nonstring='simplerepr'):
    """Make sure that a string is a byte string

    :arg obj: An object to make sure is a byte string.  In most cases this
        will be either a text string or a byte string.  However, with
        ``nonstring='simplerepr'``, this can be used as a traceback-free
        version of ``str(obj)``.
    :kwarg encoding: The encoding to use to transform from a text string to
        a byte string.  Defaults to using 'utf-8'.
    :kwarg errors: The error handler to use if the text string is not
        encodable using the specified encoding.  Any valid `codecs error
        handler <https://docs.python.org/2/library/codecs.html#codec-base-classes>`_
        may be specified. There are two additional error strategies
        specifically aimed at helping people to port code:

            :surrogate_or_strict: Will use surrogateescape if it is a valid
                handler, otherwise it will use strict
            :surrogate_or_replace: Will use surrogateescape if it is a valid
                handler, otherwise it will use replace.

        Because surrogateescape was added in Python3 this usually means that
        Python3 will use surrogateescape and Python2 will use the fallback
        error handler. Note that the code checks for surrogateescape when the
        module is imported.  If you have a backport of surrogateescape for
        python2, be sure to register the error handler prior to importing this
        module.

        The default is `surrogate_or_replace`
    :kwarg nonstring: The strategy to use if a nonstring is specified in
        ``obj``.  Default is 'simplerepr'.  Valid values are:

        :simplerepr: The default.  This takes the ``str`` of the object and
            then returns the bytes version of that string.
        :empty: Return an empty byte string
        :passthru: Return the object passed in
        :strict: Raise a :exc:`TypeError`

    :returns: Typically this returns a byte string.  If a nonstring object is
        passed in this may be a different type depending on the strategy
        specified by nonstring.  This will never return a text string.

    .. note:: If passed a byte string, this function does not check that the
        string is valid in the specified encoding.  If it's important that the
        byte string is in the specified encoding do::

            encoded_string = to_bytes(to_text(input_string, 'latin-1'), 'utf-8')
    """
    if isinstance(obj, binary_type):
        return obj

    if errors in (None, 'surrogate_or_replace'):
        if HAS_SURROGATEESCAPE:
            errors = 'surrogateescape'
        else:
            errors = 'replace'
    elif errors == 'surrogate_or_strict':
        if HAS_SURROGATEESCAPE:
            errors = 'surrogateescape'
        else:
            errors = 'strict'

    if isinstance(obj, text_type):
        return obj.encode(encoding, errors)

    # Note: We do these last even though we have to call to_bytes again on the
    # value because we're optimizing the common case
    if nonstring == 'simplerepr':
        try:
            value = str(obj)
        except UnicodeError:
            try:
                value = repr(obj)
            except UnicodeError:
                # Giving up
                return to_bytes('')
    elif nonstring == 'passthru':
        return obj
    elif nonstring == 'empty':
        # python2.4 doesn't have b''
        return to_bytes('')
    elif nonstring == 'strict':
        raise TypeError('obj must be a string type')
    else:
        raise TypeError('Invalid value %s for to_bytes\' nonstring parameter' % nonstring)

    return to_bytes(value, encoding, errors)


def to_text(obj, encoding='utf-8', errors=None, nonstring='simplerepr'):
    """Make sure that a string is a text string

    :arg obj: An object to make sure is a text string.  In most cases this
        will be either a text string or a byte string.  However, with
        ``nonstring='simplerepr'``, this can be used as a traceback-free
        version of ``str(obj)``.
    :kwarg encoding: The encoding to use to transform from a byte string to
        a text string.  Defaults to using 'utf-8'.
    :kwarg errors: The error handler to use if the byte string is not
        decodable using the specified encoding.  Any valid `codecs error
        handler <https://docs.python.org/2/library/codecs.html#codec-base-classes>`_
        may be specified. On Python3 this defaults to 'surrogateescape'.  On
        Python2, this defaults to 'replace'.
    :kwarg nonstring: The strategy to use if a nonstring is specified in
        ``obj``.  Default is 'simplerepr'.  Valid values are:

        :simplerepr: The default.  This takes the ``str`` of the object and
            then returns the text version of that string.
        :empty: Return an empty text string
        :passthru: Return the object passed in
        :strict: Raise a :exc:`TypeError`

    :returns: Typically this returns a text string.  If a nonstring object is
        passed in this may be a different type depending on the strategy
        specified by nonstring.  This will never return a byte string.
    """
    if isinstance(obj, text_type):
        return obj

    if errors in (None, 'surrogate_or_replace'):
        if HAS_SURROGATEESCAPE:
            errors = 'surrogateescape'
        else:
            errors = 'replace'
    elif errors == 'surrogate_or_strict':
        if HAS_SURROGATEESCAPE:
            errors = 'surrogateescape'
        else:
            errors = 'strict'

    if isinstance(obj, binary_type):
        return obj.decode(encoding, errors)

    # Note: We do these last even though we have to call to_text again on the
    # value because we're optimizing the common case
    if nonstring == 'simplerepr':
        try:
            value = str(obj)
        except UnicodeError:
            try:
                value = repr(obj)
            except UnicodeError:
                # Giving up
                return u''
    elif nonstring == 'passthru':
        return obj
    elif nonstring == 'empty':
        return u''
    elif nonstring == 'strict':
        raise TypeError('obj must be a string type')
    else:
        raise TypeError('Invalid value %s for to_text\'s nonstring parameter' % nonstring)

    return to_text(value, encoding, errors)


#: :py:func:`to_native`
#:      Transform a variable into the native str type for the python version
#:
#:      On Python2, this is an alias for
#:      :func:`~ansible.module_utils.to_bytes`.  On Python3 it is an alias for
#:      :func:`~ansible.module_utils.to_text`.  It makes it easier to
#:      transform a variable into the native str type for the python version
#:      the code is running on.  Use this when constructing the message to
#:      send to exceptions or when dealing with an API that needs to take
#:      a native string.  Example::
#:
#:          try:
#:              1//0
#:          except ZeroDivisionError as e:
#:              raise MyException('Encountered and error: %s' % to_native(e))
if PY3:
    to_native = to_text
else:
    to_native = to_bytes