Adds some comments + docstrings + a test case

pattern_matching/pattern_matching_v3.py

@@ -1,47 +1,51 @@
-import ipdb
 
-DEBUG = False
 def isMatch3(text, pattern):
-
+    """
+    Returns whether pattern fully matches text using the following rules:
+    ? represents exactly 1 instance of any character
+    * will match 0 or more of it's preceding character
+    literals (any non ? or * character) will match exactly 1 instance of the same character
+    """
     # Empty pattern can only match empty string
     if len(pattern) == 0:
         return len(text) == 0
-    patternindex = textindex = 0
+    patternindex = textindex = 0 # all zeroes!
     while patternindex < len(pattern):
+
         if (patternindex < len(pattern) - 1) and pattern[patternindex + 1] == "*":
-            # the current character can repeat 0,n times
-            if DEBUG:
-                ipdb.set_trace()
+            # the current pattern character can repeat 0,n times
+
+            #look ahead to get the first non text[textindex] character and the # of characters ahead it is
             future_text_literal, target_char = _scan_text_for_literal(
                 text[textindex:], character=pattern[patternindex])
+            #figure out how many instances of the x in x* we need to match, accounting for literals and ?s
+            # and ensuring the ret of the pattern can match, even if it means this doesn't match every instance of current char
             future_pattern_literal = _scan_pattern_for_literal(
                 pattern[patternindex+2:], character=pattern[patternindex], target=target_char)
+            # match_count is the # of repeating chars this * group matches
             match_count = future_text_literal - future_pattern_literal
-            if match_count > 0 and pattern[patternindex] != text[textindex]:
-                return False
+            # increase the current progress through text by the # of matched characters
             textindex = textindex + match_count
             patternindex = patternindex + 1
         elif pattern[patternindex] == "?":
+            # if the current pattern character is a ?, we just increase the indexs by 1 (pattern is down at the bottom)
             textindex = textindex + 1
         elif textindex >= len(text):
-                # we got to the end of the text before the end of the pattern, False
-                if DEBUG:
-                    ipdb.set_trace()
+                # we got to the end of the text before the end of the pattern, we're done here
                 break
         else:
             if pattern[patternindex] != text[textindex]:
-                if DEBUG:
-                    ipdb.set_trace()
+                # if literals don't match up, pattern doesn't match
                 return False
             textindex = textindex + 1
         patternindex = patternindex + 1
-    if DEBUG:
-        ipdb.set_trace()
+    # if we managed to get here and go through every character in text, the strings match
+    # if we didn't make it through every character in text, the pattern didn't match the entire string and we return False
     return textindex == len(text)
 
 
 def _scan_pattern_for_literal(text, character=None, target=None):
-    """returns index of first literal found in text, or the length of text if it doesn't exist"""
+    """returns the number of repeating <characters>, subtracting the # of '?' characters until <target> is hit"""
     count = 0
     qcount = 0
     for c in text:
@@ -52,7 +56,6 @@ def _scan_pattern_for_literal(text, character=None, target=None):
         if c not in ("?", "*", character):
             return count - qcount
         count = count + 1
-
     return count  # this happens if we get to the end of text
 
 

tests/test_pattern_matching.py

@@ -49,13 +49,15 @@ class MatcherTestCase(TestCase):
             ("aaacde", "a*aaacde", True),
             ("aaabc", "?a*b?", True),
             ("aaabc", "a*?c", True), # <-- This was the hardest test to get passing
+            ("aaaaaaab", "a*aa?ab", True),
+            ("aaabc", "a*a?b?", True)
         ]
     @skip("Tests for old implementation")
     def test_bulk(self):
         for test_case in self.test_cases:
             with self.subTest(text=test_case[0], pattern=test_case[1]):
                 match = isMatch(test_case[0], test_case[1])
-                logging.info("%s match %s = %s should be %s", # info because by default it won't log debug or info
+                logging.info("%s match %s = %s should be %s", 
                                 test_case[0], test_case[1], match, test_case[2])
                 self.assertEqual(match, test_case[2])
 
@@ -81,7 +83,7 @@ class MatcherTestCase(TestCase):
         for test_case in self.false_negatives_v2:
             with self.subTest(text=test_case[0], pattern=test_case[1]):
                 match = isMatch2(test_case[0], test_case[1])
-                logging.info("%s match %s = %s should be %s",  # info because by default it won't log debug or info
+                logging.info("%s match %s = %s should be %s",  
                              test_case[0], test_case[1], match, test_case[2])
                 self.assertEqual(match, test_case[2])
                 
@@ -89,7 +91,7 @@ class MatcherTestCase(TestCase):
         for test_case in self.test_cases:
             with self.subTest(text=test_case[0], pattern=test_case[1]):
                 match = isMatch3(test_case[0], test_case[1])
-                logging.info("%s match %s = %s should be %s",  # info because by default it won't log debug or info
+                logging.info("%s match %s = %s should be %s",  
                              test_case[0], test_case[1], match, test_case[2])
                 self.assertEqual(match, test_case[2])