coalib.parsing.StringProcessing.unescaped_rstrip() - Code Metrics - Inspection of "Makman2/dfb prerequisites" - coala-analyzer/coala - Measure and Improve Code Quality continuously with Scrutinizer

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Pull Request — master (#1099)

by Mischa

created 2015-12-01 15:42 UTC

coalib.parsing.StringProcessing.unescaped_rstrip() A

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Lines	0
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Metric	Value
cc	3
dl	0
loc	13
rs	9.4286

import re

from coalib.parsing.StringProcessing import InBetweenMatch
from coalib.parsing.StringProcessing.Filters import limit, trim_empty_matches


def search_for(pattern, string, flags=0, max_match=0, use_regex=False):
    """
    Searches for a given pattern in a string.

    :param pattern:   A pattern that defines what to match.
    :param string:    The string to search in.
    :param flags:     Additional flags to pass to the regex processor.
    :param max_match: Defines the maximum number of matches to perform. If 0 or
                      less is provided, the number of splits is not limited.
    :param use_regex: Specifies whether to treat the pattern as a regex or
                      simple string.
    :return:          An iterator returning MatchObject's.
    """
    if not use_regex:
        pattern = re.escape(pattern)

    return limit(re.finditer(pattern, string, flags), max_match)


def unescaped_search_for(pattern,
                         string,
                         flags=0,
                         max_match=0,
                         use_regex=False):
    """
    Searches for a given pattern in a string that is not escaped.

    :param pattern:   A pattern that defines what to match unescaped.
    :param string:    The string to search in.
    :param flags:     Additional flags to pass to the regex processor.
    :param max_match: Defines the maximum number of matches to perform. If 0 or
                      less is provided, the number of splits is not limited.
    :param use_regex: Specifies whether to treat the pattern as a regex or
                      simple string.
    :return:          An iterator returning MatchObject's.
    """
    _iter = limit(
        filter(lambda match: not position_is_escaped(string, match.start()),
               search_for(pattern, string, flags, 0, use_regex)),
        max_match)

    for elem in _iter:
        yield elem


def _split(string,
           max_split,
           remove_empty_matches,
           matching_function,
           *args,
           **kwargs):
    """
    Splits a string using a given matching-function that matches the separator.

    This function implements general features needed from the split functions
    in this module (the max-split and remove-empty-matches features).

    :param string:               The string where to split.
    :param max_split:            Defines the maximum number of splits. If 0 or
                                 less is provided, the number of splits is not
                                 limited.
    :param remove_empty_matches: Defines whether empty entries should
                                 be removed from the result.
    :param matching_function:    The matching function. It must return
                                 MatchObject's containing the matched
                                 split-separator.
    :param args:                 Positional arguments to invoke the
                                 matching_function with.
    :param kwargs:               Key-value arguments to invoke the
                                 matching_function with.
    """
    last_end_pos = 0

    for match in matching_function(*args, **kwargs):
        split_string = string[last_end_pos : match.start()]
        last_end_pos = match.end()

        if not remove_empty_matches or len(split_string) != 0:
            yield split_string

            max_split -= 1
            if max_split == 0:
                break  # only reachable when max_split > 0

    # Append the rest of the string.
    if not remove_empty_matches or len(string) > last_end_pos:
        yield string[last_end_pos:]


def split(pattern,
          string,
          max_split=0,
          remove_empty_matches=False,
          use_regex=False):
    """
    Splits the given string by the specified pattern. The return character (\n)
    is not a natural split pattern (if you don't specify it yourself).
    This function ignores escape sequences.

    :param pattern:              A pattern that defines where to split.
    :param string:               The string to split by the defined pattern.
    :param max_split:            Defines the maximum number of splits. If 0 or
                                 less is provided, the number of splits is not
                                 limited.
    :param remove_empty_matches: Defines whether empty entries should
                                 be removed from the result.
    :param use_regex:            Specifies whether to treat the split pattern
                                 as a regex or simple string.
    :return:                     An iterator returning the split up strings.
    """
    return _split(string,
                  max_split,
                  remove_empty_matches,
                  search_for,
                  pattern,
                  string,
                  0,
                  0,
                  use_regex)


def unescaped_split(pattern,
                    string,
                    max_split=0,
                    remove_empty_matches=False,
                    use_regex=False):
    """
    Splits the given string by the specified pattern. The return character (\n)
    is not a natural split pattern (if you don't specify it yourself).
    This function handles escaped split-patterns (and so splits only patterns
    that are unescaped).

    :param pattern:              A pattern that defines where to split.
    :param string:               The string to split by the defined pattern.
    :param max_split:            Defines the maximum number of splits. If 0 or
                                 less is provided, the number of splits is not
                                 limited.
    :param remove_empty_matches: Defines whether empty entries should
                                 be removed from the result.
    :param use_regex:            Specifies whether to treat the split pattern
                                 as a regex or simple string.
    :return:                     An iterator returning the split up strings.
    """
    return _split(string,
                  max_split,
                  remove_empty_matches,
                  unescaped_search_for,
                  pattern,
                  string,
                  0,
                  0,
                  use_regex)


def search_in_between(begin,
                      end,
                      string,
                      max_matches=0,
                      remove_empty_matches=False,
                      use_regex=False):
    """
    Searches for a string enclosed between a specified begin- and end-sequence.
    Also enclosed \n are put into the result. Doesn't handle escape sequences.

    :param begin:                A pattern that defines where to start
                                 matching.
    :param end:                  A pattern that defines where to end matching.
    :param string:               The string where to search in.
    :param max_matches           Defines the maximum number of matches. If 0 or
                                 less is provided, the number of matches is not
                                 limited.
    :param remove_empty_matches: Defines whether empty entries should
                                 be removed from the result. An entry is
                                 considered empty if no inner match was
                                 performed (regardless of matched start and
                                 end patterns).
    :param use_regex:            Specifies whether to treat the begin and end
                                 patterns as regexes or simple strings.
    :return:                     An iterator returning InBetweenMatch objects
                                 that hold information about the matched begin,
                                 inside and end string matched.
    """

    if not use_regex:
        begin = re.escape(begin)
        end = re.escape(end)
        # No need to compile the begin sequence, capturing groups get escaped.
        begin_pattern_groups = 0
    else:
        # Compilation of the begin sequence is needed to get the number of
        # capturing groups in it.
        begin_pattern_groups = re.compile(begin).groups

    # Regex explanation:
    # 1. (begin) A capturing group that matches the begin sequence.
    # 2. (.*?)   Match any char unlimited times, as few times as possible. Save
    #            the match in the second capturing group (`match.group(2)`).
    # 3. (end)   A capturing group that matches the end sequence.
    #            Because the previous group is lazy (matches as few times as
    #            possible) the next occurring end-sequence is matched.
    regex = "(" + begin + ")(.*?)(" + end + ")"

    matches = re.finditer(regex, string, re.DOTALL)

    if remove_empty_matches:
        matches = trim_empty_matches(matches,
                                     (begin_pattern_groups + 2,))

    matches = limit(matches, max_matches)

    for m in matches:
        yield InBetweenMatch.from_values(m.group(1),
                                         m.start(1),
                                         m.group(begin_pattern_groups + 2),
                                         m.start(begin_pattern_groups + 2),
                                         m.group(begin_pattern_groups + 3),
                                         m.start(begin_pattern_groups + 3))


def unescaped_search_in_between(begin,
                                end,
                                string,
                                max_matches=0,
                                remove_empty_matches=False,
                                use_regex=False):
    """
    Searches for a string enclosed between a specified begin- and end-sequence.
    Also enclosed \n are put into the result.
    Handles escaped begin- and end-sequences (and so only patterns that are
    unescaped).
    CAUTION: Using the escaped character '\' in the begin- or end-sequences
             the function can return strange results. The backslash can
             interfere with the escaping regex-sequence used internally to
             match the enclosed string.

    :param begin:                A regex pattern that defines where to start
                                 matching.
    :param end:                  A regex pattern that defines where to end
                                 matching.
    :param string:               The string where to search in.
    :param max_matches           Defines the maximum number of matches. If 0 or
                                 less is provided, the number of matches is not
                                 limited.
    :param remove_empty_matches: Defines whether empty entries should
                                 be removed from the result. An entry is
                                 considered empty if no inner match was
                                 performed (regardless of matched start and
                                 end patterns).
    :param use_regex:            Specifies whether to treat the begin and end
                                 patterns as regexes or simple strings.
    :return:                     An iterator returning the matched strings.
    """
    if not use_regex:
        begin = re.escape(begin)
        end = re.escape(end)
        # No need to compile the begin sequence, capturing groups get escaped.
        begin_pattern_groups = 0
    else:
        # Compilation of the begin sequence is needed to get the number of
        # capturing groups in it.
        begin_pattern_groups = re.compile(begin).groups

    # Regex explanation:
    # 1. (?<!\\)(?:\\\\)*   Unescapes the following char. The first part of
    #                       this regex is a look-behind assertion. Only match
    #                       the following if no single backslash is before it.
    #                       The second part matches all double backslashes.
    #                       In fact this sequence matches all escapes that
    #                       occur as a multiple of two, means the following
    #                       statement is not escaped.
    # 2. (begin)            A capturing group that matches the begin sequence.
    # 3. (.*?)              Match any char unlimited times, as few times as
    #                       possible. Save the match in the capturing group
    #                       after all capturing groups that can appear in
    #                       'begin'.
    # 4. (?<!\\)((?:\\\\)*) Again the unescaping regex, but now all escape-
    #                       characters get captured.
    # 5. (end)              A capturing group that matches the end sequence.
    #                       Because the 3. group is lazy (matches as few times
    #                       as possible) the next occurring end-sequence is
    #                       matched.
    regex = (r"(?<!\\)(?:\\\\)*(" + begin + r")(.*?)(?<!\\)((?:\\\\)*)(" +
             end + ")")

    matches = re.finditer(regex, string, re.DOTALL)

    if remove_empty_matches:
        matches = trim_empty_matches(matches,
                                     (begin_pattern_groups + 2,
                                      begin_pattern_groups + 3))

    matches = limit(matches, max_matches)

    for m in matches:
        yield InBetweenMatch.from_values(m.group(1),
                                         m.start(1),
                                         m.group(begin_pattern_groups + 2) +
                                             m.group(begin_pattern_groups + 3),
                                         m.start(begin_pattern_groups + 2),
                                         m.group(begin_pattern_groups + 4),
                                         m.start(begin_pattern_groups + 4))


def escape(string, escape_chars, escape_with="\\"):
    """
    Escapes all chars given inside the given string.

    :param string:       The string where to escape characters.
    :param escape_chars: The string or Iterable that contains the characters
                         to escape. Each char inside this string will be
                         escaped in the order given. Duplicate chars are
                         allowed.
    :param escape_with:  The string that should be used as escape sequence.
    :return:             The escaped string.
    """
    for chr in escape_chars:
        string = string.replace(chr, escape_with + chr)

    return string


def unescape(string):
    """
    Trimms off all escape characters from the given string.

    :param string: The string to unescape.
    """
    regex = r"\\(.)|\\$"

    return re.sub(regex, lambda m: m.group(1), string, 0, re.DOTALL)


def position_is_escaped(string, position=None):
    """
    Checks whether a char at a specific position of the string is preceded by
    an odd number of backslashes.

    :param string:   Arbitrary string
    :param position: Position of character in string that should be checked
    :return:         True if the character is escaped, False otherwise
    """
    escapes_uneven = False
    # iterate backwards, starting one left of position.
    # Slicing provides a sane default behaviour and prevents IndexErrors
    for i in range(len(string[:position]) - 1, -1, -1):
        if string[i] == '\\':
            escapes_uneven = not escapes_uneven
        else:
            break
    return escapes_uneven


def unescaped_rstrip(string):
    """
    Strips whitespaces from the right side of given string that are not
    escaped.

    :param string: The string where to strip whitespaces from.
    :return:       The right-stripped string.
    """
    stripped = string.rstrip()
    if (position_is_escaped(stripped, len(string)) and
            len(string) > len(stripped)):
        stripped += string[len(stripped)]
    return stripped


def unescaped_strip(string):
    """
    Strips whitespaces of the given string taking escape characters into
    account.

    :param string: The string where to strip whitespaces from.
    :return:       The stripped string.
    """
    return unescaped_rstrip(string).lstrip()


def _nested_search_in_between(begin, end, string):
    """
    Searches for a string enclosed between a specified begin- and end-sequence.
    Matches infinite times.

    This is a function specifically designed to be invoked from
    nested_search_in_between().

    :param begin:  A regex pattern that defines where to start matching.
    :param end:    A regex pattern that defines where to end matching.
    :param string: The string where to search in.
    :return:       An iterator returning the matched strings.
    """
    # Regex explanation:
    # 1. (begin) A capturing group that matches the begin sequence.
    # 2. (end)   A capturing group that matches the end sequence. Because the
    #            1st group is lazy (matches as few times as possible) the next
    #            occurring end-sequence is matched.
    # The '|' in the regex matches either the first or the second part.
    regex = "(" + begin + ")|(" + end + ")"

    left_match = None
    nesting_level = 0
    for match in re.finditer(regex, string, re.DOTALL):
        if match.group(1) is not None:
            if nesting_level == 0:
                # Store the match of the first nesting level to be able to
                # return the string until the next fitting end sequence.
                left_match = match
            nesting_level += 1
        else:
            # The second group matched. This is the only alternative if group 1
            # didn't, otherwise no match would be performed. No need to compile
            # the begin and end sequences to get the number of capturing groups
            # in them.
            if nesting_level > 0:
                nesting_level -= 1

            if nesting_level == 0 and left_match != None:
                yield InBetweenMatch.from_values(
                    left_match.group(),
                    left_match.start(),
                    string[left_match.end() : match.start()],
                    left_match.end(),
                    match.group(),
                    match.start())

                left_match = None


def nested_search_in_between(begin,
                             end,
                             string,
                             max_matches=0,
                             remove_empty_matches=False,
                             use_regex=False):
    """
    Searches for a string enclosed between a specified begin- and end-sequence.
    Also enclosed \n are put into the result. Doesn't handle escape sequences,
    but supports nesting.

    Nested sequences are ignored during the match. Means you get only the first
    nesting level returned. If you want to acquire more levels, just reinvoke
    this function again on the return value.

    Using the same begin- and end-sequence won't match anything.

    :param begin:                A pattern that defines where to start
                                 matching.
    :param end:                  A pattern that defines where to end matching.
    :param string:               The string where to search in.
    :param max_matches           Defines the maximum number of matches. If 0 or
                                 less is provided, the number of splits is not
                                 limited.
    :param remove_empty_matches: Defines whether empty entries should
                                 be removed from the result. An entry is
                                 considered empty if no inner match was
                                 performed (regardless of matched start and
                                 end patterns).
    :param use_regex:            Specifies whether to treat the begin and end
                                 patterns as regexes or simple strings.
    :return:                     An iterator returning the matched strings.
    """

    if not use_regex:
        begin = re.escape(begin)
        end = re.escape(end)

    strings = _nested_search_in_between(begin, end, string)

    if remove_empty_matches:
        strings = filter(lambda x: str(x.inside) != "", strings)

    return limit(strings, max_matches)


1			import re
2
3			from coalib.parsing.StringProcessing import InBetweenMatch
4			from coalib.parsing.StringProcessing.Filters import limit, trim_empty_matches
5
6
7			def search_for(pattern, string, flags=0, max_match=0, use_regex=False):
8			"""
9			Searches for a given pattern in a string.
10
11			:param pattern: A pattern that defines what to match.
12			:param string: The string to search in.
13			:param flags: Additional flags to pass to the regex processor.
14			:param max_match: Defines the maximum number of matches to perform. If 0 or
15			less is provided, the number of splits is not limited.
16			:param use_regex: Specifies whether to treat the pattern as a regex or
17			simple string.
18			:return: An iterator returning MatchObject's.
19			"""
20			if not use_regex:
21			pattern = re.escape(pattern)
22
23			return limit(re.finditer(pattern, string, flags), max_match)
24
25
26			def unescaped_search_for(pattern,
27			string,
28			flags=0,
29			max_match=0,
30			use_regex=False):
31			"""
32			Searches for a given pattern in a string that is not escaped.
33
34			:param pattern: A pattern that defines what to match unescaped.
35			:param string: The string to search in.
36			:param flags: Additional flags to pass to the regex processor.
37			:param max_match: Defines the maximum number of matches to perform. If 0 or
38			less is provided, the number of splits is not limited.
39			:param use_regex: Specifies whether to treat the pattern as a regex or
40			simple string.
41			:return: An iterator returning MatchObject's.
42			"""
43			_iter = limit(
44			filter(lambda match: not position_is_escaped(string, match.start()),
45			search_for(pattern, string, flags, 0, use_regex)),
46			max_match)
47
48			for elem in _iter:
49			yield elem
50
51
52			def _split(string,
53			max_split,
54			remove_empty_matches,
55			matching_function,
56			*args,
57			**kwargs):
58			"""
59			Splits a string using a given matching-function that matches the separator.
60
61			This function implements general features needed from the split functions
62			in this module (the max-split and remove-empty-matches features).
63
64			:param string: The string where to split.
65			:param max_split: Defines the maximum number of splits. If 0 or
66			less is provided, the number of splits is not
67			limited.
68			:param remove_empty_matches: Defines whether empty entries should
69			be removed from the result.
70			:param matching_function: The matching function. It must return
71			MatchObject's containing the matched
72			split-separator.
73			:param args: Positional arguments to invoke the
74			matching_function with.
75			:param kwargs: Key-value arguments to invoke the
76			matching_function with.
77			"""
78			last_end_pos = 0
79
80			for match in matching_function(args, *kwargs):
81			split_string = string[last_end_pos : match.start()]
82			last_end_pos = match.end()
83
84			if not remove_empty_matches or len(split_string) != 0:
85			yield split_string
86
87			max_split -= 1
88			if max_split == 0:
89			break # only reachable when max_split > 0
90
91			# Append the rest of the string.
92			if not remove_empty_matches or len(string) > last_end_pos:
93			yield string[last_end_pos:]
94
95
96			def split(pattern,
97			string,
98			max_split=0,
99			remove_empty_matches=False,
100			use_regex=False):
101			"""
102			Splits the given string by the specified pattern. The return character (\n)
103			is not a natural split pattern (if you don't specify it yourself).
104			This function ignores escape sequences.
105
106			:param pattern: A pattern that defines where to split.
107			:param string: The string to split by the defined pattern.
108			:param max_split: Defines the maximum number of splits. If 0 or
109			less is provided, the number of splits is not
110			limited.
111			:param remove_empty_matches: Defines whether empty entries should
112			be removed from the result.
113			:param use_regex: Specifies whether to treat the split pattern
114			as a regex or simple string.
115			:return: An iterator returning the split up strings.
116			"""
117			return _split(string,
118			max_split,
119			remove_empty_matches,
120			search_for,
121			pattern,
122			string,
123			0,
124			0,
125			use_regex)
126
127
128			def unescaped_split(pattern,
129			string,
130			max_split=0,
131			remove_empty_matches=False,
132			use_regex=False):
133			"""
134			Splits the given string by the specified pattern. The return character (\n)
135			is not a natural split pattern (if you don't specify it yourself).
136			This function handles escaped split-patterns (and so splits only patterns
137			that are unescaped).
138
139			:param pattern: A pattern that defines where to split.
140			:param string: The string to split by the defined pattern.
141			:param max_split: Defines the maximum number of splits. If 0 or
142			less is provided, the number of splits is not
143			limited.
144			:param remove_empty_matches: Defines whether empty entries should
145			be removed from the result.
146			:param use_regex: Specifies whether to treat the split pattern
147			as a regex or simple string.
148			:return: An iterator returning the split up strings.
149			"""
150			return _split(string,
151			max_split,
152			remove_empty_matches,
153			unescaped_search_for,
154			pattern,
155			string,
156			0,
157			0,
158			use_regex)
159
160
161			def search_in_between(begin,
162			end,
163			string,
164			max_matches=0,
165			remove_empty_matches=False,
166			use_regex=False):
167			"""
168			Searches for a string enclosed between a specified begin- and end-sequence.
169			Also enclosed \n are put into the result. Doesn't handle escape sequences.
170
171			:param begin: A pattern that defines where to start
172			matching.
173			:param end: A pattern that defines where to end matching.
174			:param string: The string where to search in.
175			:param max_matches Defines the maximum number of matches. If 0 or
176			less is provided, the number of matches is not
177			limited.
178			:param remove_empty_matches: Defines whether empty entries should
179			be removed from the result. An entry is
180			considered empty if no inner match was
181			performed (regardless of matched start and
182			end patterns).
183			:param use_regex: Specifies whether to treat the begin and end
184			patterns as regexes or simple strings.
185			:return: An iterator returning InBetweenMatch objects
186			that hold information about the matched begin,
187			inside and end string matched.
188			"""
189
190			if not use_regex:
191			begin = re.escape(begin)
192			end = re.escape(end)
193			# No need to compile the begin sequence, capturing groups get escaped.
194			begin_pattern_groups = 0
195			else:
196			# Compilation of the begin sequence is needed to get the number of
197			# capturing groups in it.
198			begin_pattern_groups = re.compile(begin).groups
199
200			# Regex explanation:
201			# 1. (begin) A capturing group that matches the begin sequence.
202			# 2. (.*?) Match any char unlimited times, as few times as possible. Save
203			# the match in the second capturing group (`match.group(2)`).
204			# 3. (end) A capturing group that matches the end sequence.
205			# Because the previous group is lazy (matches as few times as
206			# possible) the next occurring end-sequence is matched.
207			regex = "(" + begin + ")(.*?)(" + end + ")"
208
209			matches = re.finditer(regex, string, re.DOTALL)
210
211			if remove_empty_matches:
212			matches = trim_empty_matches(matches,
213			(begin_pattern_groups + 2,))
214
215			matches = limit(matches, max_matches)
216
217			for m in matches:
218			yield InBetweenMatch.from_values(m.group(1),
219			m.start(1),
220			m.group(begin_pattern_groups + 2),
221			m.start(begin_pattern_groups + 2),
222			m.group(begin_pattern_groups + 3),
223			m.start(begin_pattern_groups + 3))
224
225
226			def unescaped_search_in_between(begin,
227			end,
228			string,
229			max_matches=0,
230			remove_empty_matches=False,
231			use_regex=False):
232			"""
233			Searches for a string enclosed between a specified begin- and end-sequence.
234			Also enclosed \n are put into the result.
235			Handles escaped begin- and end-sequences (and so only patterns that are
236			unescaped).
237			CAUTION: Using the escaped character '\' in the begin- or end-sequences
238			the function can return strange results. The backslash can
239			interfere with the escaping regex-sequence used internally to
240			match the enclosed string.
241
242			:param begin: A regex pattern that defines where to start
243			matching.
244			:param end: A regex pattern that defines where to end
245			matching.
246			:param string: The string where to search in.
247			:param max_matches Defines the maximum number of matches. If 0 or
248			less is provided, the number of matches is not
249			limited.
250			:param remove_empty_matches: Defines whether empty entries should
251			be removed from the result. An entry is
252			considered empty if no inner match was
253			performed (regardless of matched start and
254			end patterns).
255			:param use_regex: Specifies whether to treat the begin and end
256			patterns as regexes or simple strings.
257			:return: An iterator returning the matched strings.
258			"""
259			if not use_regex:
260			begin = re.escape(begin)
261			end = re.escape(end)
262			# No need to compile the begin sequence, capturing groups get escaped.
263			begin_pattern_groups = 0
264			else:
265			# Compilation of the begin sequence is needed to get the number of
266			# capturing groups in it.
267			begin_pattern_groups = re.compile(begin).groups
268
269			# Regex explanation:
270			# 1. (?<!\\)(?:\\\\)* Unescapes the following char. The first part of
271			# this regex is a look-behind assertion. Only match
272			# the following if no single backslash is before it.
273			# The second part matches all double backslashes.
274			# In fact this sequence matches all escapes that
275			# occur as a multiple of two, means the following
276			# statement is not escaped.
277			# 2. (begin) A capturing group that matches the begin sequence.
278			# 3. (.*?) Match any char unlimited times, as few times as
279			# possible. Save the match in the capturing group
280			# after all capturing groups that can appear in
281			# 'begin'.
282			# 4. (?<!\\)((?:\\\\)*) Again the unescaping regex, but now all escape-
283			# characters get captured.
284			# 5. (end) A capturing group that matches the end sequence.
285			# Because the 3. group is lazy (matches as few times
286			# as possible) the next occurring end-sequence is
287			# matched.
288			regex = (r"(?<!\\)(?:\\\\)(" + begin + r")(.?)(?<!\\)((?:\\\\)*)(" +
289			end + ")")
290
291			matches = re.finditer(regex, string, re.DOTALL)
292
293			if remove_empty_matches:
294			matches = trim_empty_matches(matches,
295			(begin_pattern_groups + 2,
296			begin_pattern_groups + 3))
297
298			matches = limit(matches, max_matches)
299
300			for m in matches:
301			yield InBetweenMatch.from_values(m.group(1),
302			m.start(1),
303			m.group(begin_pattern_groups + 2) +
304			m.group(begin_pattern_groups + 3),
305			m.start(begin_pattern_groups + 2),
306			m.group(begin_pattern_groups + 4),
307			m.start(begin_pattern_groups + 4))
308
309
310			def escape(string, escape_chars, escape_with="\\"):
311			"""
312			Escapes all chars given inside the given string.
313
314			:param string: The string where to escape characters.
315			:param escape_chars: The string or Iterable that contains the characters
316			to escape. Each char inside this string will be
317			escaped in the order given. Duplicate chars are
318			allowed.
319			:param escape_with: The string that should be used as escape sequence.
320			:return: The escaped string.
321			"""
322			for chr in escape_chars:
323			string = string.replace(chr, escape_with + chr)
324
325			return string
326
327
328			def unescape(string):
329			"""
330			Trimms off all escape characters from the given string.
331
332			:param string: The string to unescape.
333			"""
334			regex = r"\\(.)\|\\$"
335
336			return re.sub(regex, lambda m: m.group(1), string, 0, re.DOTALL)
337
338
339			def position_is_escaped(string, position=None):
340			"""
341			Checks whether a char at a specific position of the string is preceded by
342			an odd number of backslashes.
343
344			:param string: Arbitrary string
345			:param position: Position of character in string that should be checked
346			:return: True if the character is escaped, False otherwise
347			"""
348			escapes_uneven = False
349			# iterate backwards, starting one left of position.
350			# Slicing provides a sane default behaviour and prevents IndexErrors
351			for i in range(len(string[:position]) - 1, -1, -1):
352			if string[i] == '\\':
353			escapes_uneven = not escapes_uneven
354			else:
355			break
356			return escapes_uneven
357
358
359			def unescaped_rstrip(string):
360			"""
361			Strips whitespaces from the right side of given string that are not
362			escaped.
363
364			:param string: The string where to strip whitespaces from.
365			:return: The right-stripped string.
366			"""
367			stripped = string.rstrip()
368			if (position_is_escaped(stripped, len(string)) and
369			len(string) > len(stripped)):
370			stripped += string[len(stripped)]
371			return stripped
372
373
374			def unescaped_strip(string):
375			"""
376			Strips whitespaces of the given string taking escape characters into
377			account.
378
379			:param string: The string where to strip whitespaces from.
380			:return: The stripped string.
381			"""
382			return unescaped_rstrip(string).lstrip()
383
384
385			def _nested_search_in_between(begin, end, string):
386			"""
387			Searches for a string enclosed between a specified begin- and end-sequence.
388			Matches infinite times.
389
390			This is a function specifically designed to be invoked from
391			nested_search_in_between().
392
393			:param begin: A regex pattern that defines where to start matching.
394			:param end: A regex pattern that defines where to end matching.
395			:param string: The string where to search in.
396			:return: An iterator returning the matched strings.
397			"""
398			# Regex explanation:
399			# 1. (begin) A capturing group that matches the begin sequence.
400			# 2. (end) A capturing group that matches the end sequence. Because the
401			# 1st group is lazy (matches as few times as possible) the next
402			# occurring end-sequence is matched.
403			# The '\|' in the regex matches either the first or the second part.
404			regex = "(" + begin + ")\|(" + end + ")"
405
406			left_match = None
407			nesting_level = 0
408			for match in re.finditer(regex, string, re.DOTALL):
409			if match.group(1) is not None:
410			if nesting_level == 0:
411			# Store the match of the first nesting level to be able to
412			# return the string until the next fitting end sequence.
413			left_match = match
414			nesting_level += 1
415			else:
416			# The second group matched. This is the only alternative if group 1
417			# didn't, otherwise no match would be performed. No need to compile
418			# the begin and end sequences to get the number of capturing groups
419			# in them.
420			if nesting_level > 0:
421			nesting_level -= 1
422
423			if nesting_level == 0 and left_match != None:
424			yield InBetweenMatch.from_values(
425			left_match.group(),
426			left_match.start(),
427			string[left_match.end() : match.start()],
428			left_match.end(),
429			match.group(),
430			match.start())
431
432			left_match = None
433
434
435			def nested_search_in_between(begin,
436			end,
437			string,
438			max_matches=0,
439			remove_empty_matches=False,
440			use_regex=False):
441			"""
442			Searches for a string enclosed between a specified begin- and end-sequence.
443			Also enclosed \n are put into the result. Doesn't handle escape sequences,
444			but supports nesting.
445
446			Nested sequences are ignored during the match. Means you get only the first
447			nesting level returned. If you want to acquire more levels, just reinvoke
448			this function again on the return value.
449
450			Using the same begin- and end-sequence won't match anything.
451
452			:param begin: A pattern that defines where to start
453			matching.
454			:param end: A pattern that defines where to end matching.
455			:param string: The string where to search in.
456			:param max_matches Defines the maximum number of matches. If 0 or
457			less is provided, the number of splits is not
458			limited.
459			:param remove_empty_matches: Defines whether empty entries should
460			be removed from the result. An entry is
461			considered empty if no inner match was
462			performed (regardless of matched start and
463			end patterns).
464			:param use_regex: Specifies whether to treat the begin and end
465			patterns as regexes or simple strings.
466			:return: An iterator returning the matched strings.
467			"""
468
469			if not use_regex:
470			begin = re.escape(begin)
471			end = re.escape(end)
472
473			strings = _nested_search_in_between(begin, end, string)
474
475			if remove_empty_matches:
476			strings = filter(lambda x: str(x.inside) != "", strings)
477
478			return limit(strings, max_matches)
479

coala-analyzer / coala

Pull Request — master (#1099)

coalib.parsing.StringProcessing.unescaped_rstrip() A

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