From 0038868f5831e9eab62778f7a729da8587908a89 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marek=20Sieroci=C5=84ski?= <mareksierocinski@gmail.com>
Date: Tue, 16 Nov 2021 17:44:47 +0100
Subject: [PATCH] Changed order of transformation arguments

---
 README.md         |  2 +-
 casey/__init__.py | 28 ++++++++++++++++++++--------
 pyproject.toml    |  2 +-
 tests/__main__.py | 27 +++++++++++++++++++++++++++
 4 files changed, 49 insertions(+), 10 deletions(-)

diff --git a/README.md b/README.md
index 8d14965..7d8f813 100644
--- a/README.md
+++ b/README.md
@@ -45,7 +45,7 @@ print(casey.snake(subject))
 print(casey.snake(subject, upper=True))
 # Prints: EVERY_1_WORD_IS_VERY_IMPORTANT
 
-def my_transformation(idx: int, word: str) -> str:
+def my_transformation(word: str, idx: int) -> str:
   if idx % 2 == 0:
     return word.lower()
   else:
diff --git a/casey/__init__.py b/casey/__init__.py
index dbb1fbc..8cf2307 100644
--- a/casey/__init__.py
+++ b/casey/__init__.py
@@ -1,5 +1,6 @@
 import re
 from typing import List, Callable, Union
+from inspect import signature
 
 
 def clean(subject: str) -> str:
@@ -38,17 +39,28 @@ def clean_list(subject: str) -> List[str]:
 def transform(subject: str, transformation: Union[Callable, None], glue=" ") -> str:
     normalized = clean_list(subject)
     words = []
-    for idx, word in enumerate(normalized):
-        if transformation:
-            w = transformation(idx, word)
-        else:
-            w = word
-        words.append(w)
+
+    if transformation:
+        sig = signature(transformation)
+        params_number = len(sig.parameters)
+
+        for idx, word in enumerate(normalized):
+            if params_number == 0:
+                w = transformation()
+            elif params_number == 1:
+                w = transformation(word)
+            elif params_number == 2:
+                w = transformation(word, idx)
+            else:
+                raise Exception("Wrong number of arguments for transformation")
+            words.append(w)
+    else:
+        words = normalized
 
     return glue.join(words)
 
 
-def _camel_transformation(idx: int, word: str) -> str:
+def _camel_transformation(word: str, idx: int) -> str:
     if idx == 0:
         return word
     else:
@@ -62,7 +74,7 @@ def camel(subject: str) -> str:
     return transform(subject, _camel_transformation, "")
 
 
-def _pascal_transformation(idx: int, word: str) -> str:
+def _pascal_transformation(word: str, _) -> str:
     return upper_first(word)
 
 
diff --git a/pyproject.toml b/pyproject.toml
index 9c05617..3a76660 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "casey"
-version = "1.1.0"
+version = "1.2.0"
 description = "A simple library to support various naming conventions and convert strings from one to another"
 authors = [
     "Marek Sierociński <mareksierocinski@gmail.com>"
diff --git a/tests/__main__.py b/tests/__main__.py
index 8343757..c6bd420 100644
--- a/tests/__main__.py
+++ b/tests/__main__.py
@@ -206,6 +206,33 @@ def test_lower_first(self):
             'Return string with very first letter lower'
         )
 
+    def test_transform(self):
+        phrase = "Every 1 WORD, is very IMPORTANT!"
+
+        self.assertEqual(
+            casey.transform(phrase, None, '_'),
+            'every_1_WORD_is_very_IMPORTANT',
+            'Return glued with underscore string'
+        )
+
+        self.assertEqual(
+            casey.transform(phrase, lambda: "x", '_'),
+            'x_x_x_x_x_x',
+            'Return string for transformation without any argument'
+        )
+
+        self.assertEqual(
+            casey.transform(phrase, lambda word: word.upper(), '__'),
+            'EVERY__1__WORD__IS__VERY__IMPORTANT',
+            'Return string for transformation with one argument'
+        )
+
+        self.assertEqual(
+            casey.transform(phrase, lambda word, idx: word.upper() + str(idx), '__'),
+            'EVERY0__11__WORD2__IS3__VERY4__IMPORTANT5',
+            'Return string for transformation with two arguments'
+        )
+
 
 if __name__ == '__main__':
     unittest.main()