From 6932fc110e1a6d734675a09fd6f5d889be1250b7 Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Sat, 27 Jun 2026 20:51:07 +0100
Subject: Add lowerCamelCaseToSnakeCase

---
 .../java/org/zwobble/hobgoblin/compiler/util/Casing.java   | 14 ++++++++++++++
 .../org/zwobble/hobgoblin/compiler/util/CasingTests.java   | 14 ++++++++++++++
 2 files changed, 28 insertions(+)

(limited to 'src')

diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/util/Casing.java b/src/main/java/org/zwobble/hobgoblin/compiler/util/Casing.java
index ac0871b..e99aec6 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/util/Casing.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/util/Casing.java
@@ -24,4 +24,18 @@ public class Casing {
 
         return upperCase.toString();
     }
+
+    public static String lowerCamelCaseToSnakeCase(String lowerCamelCase) {
+        var snakeCase = new StringBuilder();
+
+        for (var characterIndex = 0; characterIndex < lowerCamelCase.length(); characterIndex++) {
+            var character = lowerCamelCase.charAt(characterIndex);
+            if (Character.isUpperCase(character) || Character.isDigit(character)) {
+                snakeCase.append('_');
+            }
+            snakeCase.append(Character.toLowerCase(character));
+        }
+
+        return snakeCase.toString();
+    }
 }
diff --git a/src/test/java/org/zwobble/hobgoblin/compiler/util/CasingTests.java b/src/test/java/org/zwobble/hobgoblin/compiler/util/CasingTests.java
index fbdf429..561ec8a 100644
--- a/src/test/java/org/zwobble/hobgoblin/compiler/util/CasingTests.java
+++ b/src/test/java/org/zwobble/hobgoblin/compiler/util/CasingTests.java
@@ -20,4 +20,18 @@ public class CasingTests {
 
         assertThat(result, equalTo(expectedUpperCase));
     }
+
+    @ParameterizedTest
+    @CsvSource({
+        "a,a",
+        "abc,abc",
+        "abcDef,abc_def",
+        "abDeFg,ab_de_fg",
+        "a0,a_0",
+    })
+    public void lowerCamelCaseToSnakeCase(String lowerCamelCase, String expectedUpperCase) {
+        var result = Casing.lowerCamelCaseToSnakeCase(lowerCamelCase);
+
+        assertThat(result, equalTo(expectedUpperCase));
+    }
 }
-- 
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