feat(140 day): convert variable names from multiple formats to SCREAMING_SNAKE_CASE using regex-based normalization

Author: JohnSunny21

FreeCodeCamp/CodingQ/ScreamingSnakeCase.py

@@ -0,0 +1,126 @@
+"""  
+
+SCREAMING_SNAKE_CASE
+Given a string representing a variable name, return the variable name converted to SCREAMING_SNAKE_CASE.
+
+The given variable names will be written in one of the following formats:
+
+camelCase
+PascalCase
+snake_case
+kebab-case
+In the above formats, words are separated by an underscore (_), a hyphen (-), or a new word starts with a capital letter.
+
+To convert to SCREAMING_SNAKE_CASE:
+
+Make all letters uppercase
+Separate words with an underscore (_)
+"""
+
+import unittest
+
+class ScreamingSnakeCaseTest(unittest.TestCase):
+
+    def test1(self):
+        self.assertEqual(to_screaming_snake_case("userEmail"),"USER_EMAIL")
+
+
+    def test2(self):
+        self.assertEqual(to_screaming_snake_case("UserPassword"),"USER_PASSWORD")
+
+    def test3(self):
+        self.assertEqual(to_screaming_snake_case("user_id"),"USER_ID")
+
+
+    def test4(self):
+        self.assertEqual(to_screaming_snake_case("user-address"),"USER_ADDRESS")
+
+    def test5(self):
+        self.assertEqual(to_screaming_snake_case("username"),"USERNAME")
+
+
+
+def to_screaming_snake_case(variable_name):
+    result = []
+
+    if '-' in variable_name:
+        result = variable_name.split('-')
+    elif '_' in variable_name:
+        result = variable_name.split('_')
+    
+    res = ""
+
+    if not result:
+        for index, char in enumerate(variable_name):
+            if char.isupper() and index != 0:
+                res += "_"+char
+            else:
+                res += char.upper()
+
+        
+    return res if res else '_'.join(result).upper()
+
+
+"""
+Minor Issues for the above solution
+
+1. Initialization of result
+    -> You set result = [] and later overwrite it with a list of words if - or _ is found.
+    -> That works, but it's a bit confusing because result is sometimes a list of words and sometimes just an empty list.
+
+2. Mixed fomats
+    -> if a variable name consists both - and _ (eg. "myVar-name_test"), the above code only handles once separator.
+    -> This solution words it explicitly mentioned for kebab-case, PascalCase, snake_case and camelCase . there is no case involving both the '-' and '_' together.
+
+This solution is funcationally correct and meets the requirements. The refinements below just make it more robust and concise.
+"""
+
+
+import re
+def to_screaming_snake_case(variable_name):
+    # Step 1: Replace hyphens with underscores
+
+    variable_name = variable_name.replace('-','_')
+
+
+    # Step 2: Insert underscores before capital letters (for camelCase/ PascalCase)
+    variable_name = re.sub(r'([a-z0-9])([A-Z])',r'\1_\2',variable_name)
+
+    return variable_name.upper()
+
+
+""" 
+
+
+ Example: "UserPassword"
+- First two characters: "Us" → U is uppercase, s is lowercase.
+Regex looks for lowercase/digit followed by uppercase. Here we have uppercase followed by lowercase, so no match.
+→ No underscore before the first U.
+- Later: "rP" → r is lowercase, P is uppercase.
+Regex matches this pair.
+Replacement: "r_P".
+→ Underscore inserted between r and P.
+Final result: "User_Password" → then .upper() → "USER_PASSWORD".
+
+✅ Why it doesn’t add _ before the first U
+Because the regex requires a lowercase/digit before the uppercase.
+At the start of "UserPassword", the U has no preceding lowercase/digit — it’s the first character. So the pattern doesn’t match there.
+
+🧠 Key Takeaway
+- The regex only splits at lowercase→uppercase boundaries (like rP, eM, dA).
+- It does not split at the very beginning if the string starts with an uppercase letter.
+- That’s why "UserPassword" becomes "USER_PASSWORD", not "_USER_PASSWORD".
+
+=> Hyphens (-) -> underscores (_)
+=> Insert underscores before capital letters to split camelCase/PascalCase.
+=> Convert everything to uppercase.
+=> Works for all four formats.
+
+"""
+
+
+
+
+if __name__ == "__main__":
+    print(to_screaming_snake_case("userNamePassword"))
+    unittest.main()