pppoe-server: T3006: Add range to regex generator

1 files changed, 142 insertions, 0 deletions

diff --git a/python/vyos/range_regex.py b/python/vyos/range_regex.py
new file mode 100644
index 000000000..a8190d140
--- /dev/null
+++ b/python/vyos/range_regex.py
@@ -0,0 +1,142 @@
+'''Copyright (c) 2013, Dmitry Voronin
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this
+list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright notice,
+this list of conditions and the following disclaimer in the documentation
+and/or other materials provided with the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+'''
+import math
+
+# coding=utf8
+
+#  Split range to ranges that has its unique pattern.
+#  Example for 12-345:
+#
+#  12- 19: 1[2-9]
+#  20- 99: [2-9]\d
+# 100-299: [1-2]\d{2}
+# 300-339: 3[0-3]\d
+# 340-345: 34[0-5]
+
+def range_to_regex(inpt_range):
+    if isinstance(inpt_range, str):
+        range_list = inpt_range.split('-')
+        # Check input arguments
+        if len(range_list) == 2:
+            # The first element in range must be higher then the second
+            if int(range_list[0]) < int(range_list[1]):
+                return regex_for_range(int(range_list[0]), int(range_list[1]))
+
+    return None
+
+def bounded_regex_for_range(min_, max_):
+    return r'\b({})\b'.format(regex_for_range(min_, max_))
+
+def regex_for_range(min_, max_):
+    """
+    > regex_for_range(12, 345)
+    '1[2-9]|[2-9]\d|[1-2]\d{2}|3[0-3]\d|34[0-5]'
+    """
+    positive_subpatterns = []
+    negative_subpatterns = []
+
+    if min_ < 0:
+        min__ = 1
+        if max_ < 0:
+            min__ = abs(max_)
+        max__ = abs(min_)
+
+        negative_subpatterns = split_to_patterns(min__, max__)
+        min_ = 0
+
+    if max_ >= 0:
+        positive_subpatterns = split_to_patterns(min_, max_)    
+
+    negative_only_subpatterns = ['-' + val for val in negative_subpatterns if val not in positive_subpatterns]
+    positive_only_subpatterns = [val for val in positive_subpatterns if val not in negative_subpatterns]
+    intersected_subpatterns = ['-?' + val for val in negative_subpatterns if val in positive_subpatterns]
+
+    subpatterns = negative_only_subpatterns + intersected_subpatterns + positive_only_subpatterns
+    return '|'.join(subpatterns)
+
+
+def split_to_patterns(min_, max_):
+    subpatterns = []
+
+    start = min_
+    for stop in split_to_ranges(min_, max_):
+        subpatterns.append(range_to_pattern(start, stop))
+        start = stop + 1
+
+    return subpatterns
+
+
+def split_to_ranges(min_, max_):
+    stops = {max_}
+
+    nines_count = 1
+    stop = fill_by_nines(min_, nines_count)
+    while min_ <= stop < max_:
+        stops.add(stop)
+
+        nines_count += 1
+        stop = fill_by_nines(min_, nines_count)
+
+    zeros_count = 1
+    stop = fill_by_zeros(max_ + 1, zeros_count) - 1
+    while min_ < stop <= max_:
+        stops.add(stop)
+
+        zeros_count += 1
+        stop = fill_by_zeros(max_ + 1, zeros_count) - 1
+
+    stops = list(stops)
+    stops.sort()
+
+    return stops
+
+
+def fill_by_nines(integer, nines_count):
+    return int(str(integer)[:-nines_count] + '9' * nines_count)
+
+
+def fill_by_zeros(integer, zeros_count):
+    return integer - integer % 10 ** zeros_count
+
+
+def range_to_pattern(start, stop):
+    pattern = ''
+    any_digit_count = 0
+
+    for start_digit, stop_digit in zip(str(start), str(stop)):
+        if start_digit == stop_digit:
+            pattern += start_digit
+        elif start_digit != '0' or stop_digit != '9':
+            pattern += '[{}-{}]'.format(start_digit, stop_digit)
+        else:
+            any_digit_count += 1
+
+    if any_digit_count:
+        pattern += r'\d'
+
+    if any_digit_count > 1:
+        pattern += '{{{}}}'.format(any_digit_count)
+
+    return pattern
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