Implement index-of expression (#1113)

platform/android/CHANGELOG.md

@@ -7,6 +7,7 @@ MapLibre welcomes participation and contributions from everyone. Please read [`C
 ### ✨ Features and improvements
 
 * Change to a more natural fling animation and allow setting `flingThreshold` and `flingAnimationBaseTime` in `UiSettings` ([#963](https://github.com/maplibre/maplibre-native/pull/963))
+* Add support for [index-of expression](https://maplibre.org/maplibre-style-spec/expressions/#index-of) ([#1113](https://github.com/maplibre/maplibre-native/pull/1113))
 
 ### 🐞 Bug fixes
 

platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/style/expressions/Expression.java

@@ -1552,6 +1552,31 @@ public class Expression {
     return new Expression("in", needle, haystack);
   }
 
+  /**
+   * Returns the first position at which a `needle` can be found in a `haystack`. 
+   *
+   * @param needle   the item expression
+   * @param haystack the array or string expression
+   * @return position in the array or string or -1 if not found.
+   * @see <a href="https://maplibre.org/maplibre-gl-js-docs/style-spec/#index-of">Style specification</a>
+   */
+  public static Expression indexOf(@NonNull Expression keyword, @NonNull Expression input) {
+    return new Expression("index-of", keyword, input);
+  }
+
+  /**
+   * Returns the first position at which a `needle` can be found in a `haystack`. 
+   *
+   * @param needle   the item expression
+   * @param haystack the array or string expression
+   * @param fromIndex the index to start searching from
+   * @return position in the array or string or -1 if not found.
+   * @see <a href="https://maplibre.org/maplibre-gl-js-docs/style-spec/#index-of">Style specification</a>
+   */
+  public static Expression indexOf(@NonNull Expression keyword, @NonNull Expression input, @NonNull Expression fromIndex) {
+    return new Expression("index-of", keyword, input, fromIndex);
+  }
+
   /**
    * Retrieves whether an item exists in an array or a substring exists in a string.
    *

platform/android/MapboxGLAndroidSDK/src/test/java/com/mapbox/mapboxsdk/style/expressions/ExpressionTest.kt

@@ -455,6 +455,27 @@ class ExpressionTest {
         Assert.assertTrue("expression should match", Arrays.deepEquals(expected, actual))
     }
 
+    @Test
+    @Throws(Exception::class)
+    fun testIndexOf() {
+        val expected = arrayOf<Any>("index-of", 2f, arrayOf<Any>("literal", arrayOf<Any>(1f, 2f, 3f)))
+        val actual =
+            Expression.indexOf(Expression.literal(2f), Expression.literal(arrayOf<Any>(1f, 2f, 3f)))
+                .toArray()
+        Assert.assertTrue("expression should match", Arrays.deepEquals(expected, actual))
+    }
+
+
+    @Test
+    @Throws(Exception::class)
+    fun testIndexOfWithFromIndex() {
+        val expected = arrayOf<Any>("index-of", 2f, arrayOf<Any>("literal", arrayOf<Any>(1f, 2f, 3f)), 1f)
+        val actual =
+            Expression.indexOf(Expression.literal(2f), Expression.literal(arrayOf<Any>(1f, 2f, 3f)), Expression.literal(1f))
+                .toArray()
+        Assert.assertTrue("expression should match", Arrays.deepEquals(expected, actual))
+    }
+
     @Test
     @Throws(Exception::class)
     fun testInNumber() {