Enhanced to support negative values for ranges.

Author: mbayadinov

range_regex/range_regex.py

@@ -1,3 +1,5 @@
+import math
+
 # coding=utf8
 
 #  Split range to ranges that has its unique pattern.
@@ -19,14 +21,38 @@ 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 '|'.join(subpatterns)
+    return subpatterns
 
 
 def split_to_ranges(min_, max_):

range_regex/tests.py

@@ -12,11 +12,28 @@ def _verify_range(self, regex, min_, max_, from_min_, to_max_):
 
     def test_quality(self):
         self.assertEqual(regex_for_range(1, 1), '1')
+        self.assertEqual(regex_for_range(0, 1), '[0-1]')
+        self.assertEqual(regex_for_range(-1, -1), '-1')
+        self.assertEqual(regex_for_range(-1, 0), '-1|0')
+        self.assertEqual(regex_for_range(-1, 1), '-1|[0-1]')
+        self.assertEqual(regex_for_range(-4, -2), '-[2-4]')
+        self.assertEqual(regex_for_range(-3, 1), '-[1-3]|[0-1]')
+        self.assertEqual(regex_for_range(-2, 0), '-[1-2]|0')
+        self.assertEqual(regex_for_range(0, 2), '[0-2]')
+        self.assertEqual(regex_for_range(-1, 3), '-1|[0-3]')
         self.assertEqual(regex_for_range(65666, 65667), '6566[6-7]')
         self.assertEqual(regex_for_range(12, 3456), r'1[2-9]|[2-9]\d|[1-9]\d{2}|[1-2]\d{3}|3[0-3]\d{2}|34[0-4]\d|345[0-6]')
         self.assertEqual(regex_for_range(1, 19), r'[1-9]|1\d')
         self.assertEqual(regex_for_range(1, 99), r'[1-9]|[1-9]\d')
 
+    def test_optimization(self):
+        self.assertEqual(regex_for_range(-9, 9), r'-[1-9]|\d')
+        self.assertEqual(regex_for_range(-19, 19), r'-[1-9]|-?1\d|\d')
+        self.assertEqual(regex_for_range(-29, 29), r'-[1-9]|-?[1-2]\d|\d')
+        self.assertEqual(regex_for_range(-99, 99), r'-[1-9]|-?[1-9]\d|\d')
+        self.assertEqual(regex_for_range(-999, 999), r'-[1-9]|-?[1-9]\d|-?[1-9]\d{2}|\d')
+        self.assertEqual(regex_for_range(-9999, 9999), r'-[1-9]|-?[1-9]\d|-?[1-9]\d{2}|-?[1-9]\d{3}|\d')
+        
     def test_equal(self):
         regex = bounded_regex_for_range(1, 1)
         self._verify_range(regex, 1, 1, 0, 100)