From 539edbcbc9923d24f7903294063da9609875e0d3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fran=C3=A7ois=20Perin?= <f.perin@smartway.ai>
Date: Fri, 3 Nov 2023 15:03:22 +0100
Subject: [PATCH] :sparkles: Add left-strip preprocessor

---
 README.md                    |  1 +
 magicparse/pre_processors.py | 14 +++++++++++++-
 tests/test_pre_processors.py | 21 +++++++++++++++++++++
 3 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 4f1f6d4..6c5b9e7 100644
--- a/README.md
+++ b/README.md
@@ -111,6 +111,7 @@ assert rows == [{"name": "Joe"}, {"name": "William"}, {"name": "Jack"}, {"name":
 - regex-extract
 - replace
 - strip-whitespaces
+- left-strip
 
 #### Validators
 
diff --git a/magicparse/pre_processors.py b/magicparse/pre_processors.py
index d3f65b9..cc1f25f 100644
--- a/magicparse/pre_processors.py
+++ b/magicparse/pre_processors.py
@@ -73,6 +73,18 @@ def key() -> str:
         return "strip-whitespaces"
 
 
+class LeftStrip(PreProcessor):
+    def __init__(self, characters: str) -> None:
+        self.characters = characters
+
+    def apply(self, value: str) -> str:
+        return value.lstrip(self.characters)
+
+    @staticmethod
+    def key() -> str:
+        return "left-strip"
+
+
 class RegexExtract(PreProcessor):
     def __init__(self, pattern: str) -> None:
         pattern = re.compile(pattern)
@@ -97,4 +109,4 @@ def key() -> str:
         return "regex-extract"
 
 
-builtins = [LeftPadZeroes, Map, RegexExtract, Replace, StripWhitespaces]
+builtins = [LeftPadZeroes, Map, RegexExtract, Replace, StripWhitespaces, LeftStrip]
diff --git a/tests/test_pre_processors.py b/tests/test_pre_processors.py
index cdec6b2..2f5fb6e 100644
--- a/tests/test_pre_processors.py
+++ b/tests/test_pre_processors.py
@@ -6,6 +6,7 @@
     RegexExtract,
     Replace,
     StripWhitespaces,
+    LeftStrip,
 )
 import pytest
 from unittest import TestCase
@@ -38,6 +39,12 @@ def test_strip_whitespaces(self):
         pre_processor = PreProcessor.build({"name": "strip-whitespaces"})
         assert isinstance(pre_processor, StripWhitespaces)
 
+    def test_left_strip(self):
+        pre_processor = PreProcessor.build(
+            {"name": "left-strip", "parameters": {"characters": "0"}}
+        )
+        assert isinstance(pre_processor, LeftStrip)
+
     def test_regex_extract(self):
         pre_processor = PreProcessor.build(
             {
@@ -114,6 +121,20 @@ def test_success(self):
         assert pre_processor.apply("    an input     ") == "an input"
 
 
+class TestLeftStrip(TestCase):
+    def test_do_nothing(self):
+        pre_processor = PreProcessor.build(
+            {"name": "left-strip", "parameters": {"characters": "0"}}
+        )
+        assert pre_processor.apply("12345") == "12345"
+
+    def test_success(self):
+        pre_processor = PreProcessor.build(
+            {"name": "left-strip", "parameters": {"characters": "0"}}
+        )
+        assert pre_processor.apply("0000012345") == "12345"
+
+
 class TestRegexExtract(TestCase):
     def test_build_without_value_group(self):
         with pytest.raises(