knipknap/exscript

#
# Copyright (C) 2010-2017 Samuel Abels
# The MIT License (MIT)
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files
# (the "Software"), to deal in the Software without restriction,
# including without limitation the rights to use, copy, modify, merge,
# publish, distribute, sublicense, and/or sell copies of the Software,
# and to permit persons to whom the Software is furnished to do so,
# subject to the following conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
# IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
# CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
# TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
"""
Shorthands for regular expression matching.
"""
from __future__ import print_function, absolute_import
import re
from ..protocols import Protocol


def _first_match(string, compiled):
    match = compiled.search(string)
    if match is None and compiled.groups <= 1:
        return None
    elif match is None:
        return (None,) * compiled.groups
    elif compiled.groups == 0:
        return string
    elif compiled.groups == 1:
        return match.groups()[0]
    else:
        return match.groups()


def first_match(string, regex, flags=re.M):
    """
    Matches the given string against the given regex.

      - If no match is found and the regular expression has zero or one
        groups, this function returns None.

      - If no match is found and the regular expression has more than one
        group, this function returns a tuple of None. The number of elements
        in the tuple equals the number of groups in the regular expression.

      - If a match is found and the regular expression has no groups,
        the entire string is returned.

      - If a match is found and the regular expression has one group,
        the matching string from the group is returned.

      - If a match is found and the regular expression has multiple groups,
        a tuple containing the matching strings from the groups is returned.

    This behavior ensures that the following assignments can never fail::

       foo   = 'my test'
       match = first_match(foo, r'aaa')         # Returns None
       match = first_match(foo, r'\S+')         # Returns 'my test'
       match = first_match(foo, r'(aaa)')       # Returns None
       match = first_match(foo, r'(\S+)')       # Returns 'my'
       match = first_match(foo, r'(aaa) (\S+)') # Returns (None, None)
       match = first_match(foo, r'(\S+) (\S+)') # Returns ('my', 'foo')

    :type  string: string|Exscript.protocols.Protocol
    :param string: The string that is matched, or a Protocol object.
    :type  regex: string
    :param regex: A regular expression.
    :type  flags: int
    :param flags: The flags for compiling the regex; e.g. re.I
    :rtype:  string|tuple
    :return: A match, or a tuple of matches.
    """
    if isinstance(string, Protocol):
        string = string.response
    return _first_match(string, re.compile(regex, flags))


def any_match(string, regex, flags=re.M):
    """
    Matches the given string against the given regex.

      - If no match is found, this function returns an empty list.

      - If a match is found and the regular expression has no groups,
        a list of matching lines returned.

      - If a match is found and the regular expression has one group,
        a list of matching strings is returned.

      - If a match is found and the regular expression has multiple groups,
        a list containing tuples of matching strings is returned.

    This behavior ensures that the following can never fail::

        foo = '1 uno\\n2 due'
        for m in any_match(foo, r'aaa'):         # Returns []
            print(m)

        for m in any_match(foo, r'\S+'):         # Returns ['1 uno', '2 due']
            print(m)

        for m in any_match(foo, r'(aaa)'):       # Returns []
            print(m)

        for m in any_match(foo, r'(\S+)'):       # Returns ['1', '2']
            print(m)

        for one, two in any_match(foo, r'(aaa) (\S+)'): # Returns []
            print(m)

        for one, two in any_match(foo, r'(\S+) (\S+)'): # Returns [('1', 'uno'), ('2', 'due')]
            print(m)

    :type  string: string|Exscript.protocols.Protocol
    :param string: The string that is matched, or a Protocol object.
    :type  regex: string
    :param regex: A regular expression.
    :type  flags: int
    :param flags: The flags for compiling the regex; e.g. re.I
    :rtype:  list[string|tuple]
    :return: A list of strings, or a list of tuples.
    """
    if isinstance(string, Protocol):
        string = string.response
    compiled = re.compile(regex, flags)
    results = []
    if compiled.groups <= 1:
        for line in string.split('\n'):
            match = _first_match(line, compiled)
            if match is None:
                continue
            results.append(match)
    else:
        for line in string.split('\n'):
            match = _first_match(line, compiled)
            if match[0] is None:
                continue
            results.append(match)
    return results