Implemented TSNode.getFieldNameForChild()

Author: itsaky

android-tree-sitter/src/main/java/com/itsaky/androidide/treesitter/TSNode.java

@@ -15,6 +15,12 @@ public class TSNode {
 
   public TSNode() {}
 
+  /**
+   * Get the child of the given node at the child index.
+   *
+   * @param index The index of the child.
+   * @return The child at the child index.
+   */
   public TSNode getChild(int index) {
     final var count = getChildCount();
     if (index < 0 || index >= count) {
@@ -24,6 +30,12 @@ public TSNode getChild(int index) {
     return getChildAt(index);
   }
 
+  /**
+   * Get the named child of the given node at the given index.
+   *
+   * @param index The index of the named child.
+   * @return The named child node at the given index.
+   */
   public TSNode getNamedChild(int index) {
     final var count = getNamedChildCount();
     if (index < 0 || index >= count) {
@@ -33,6 +45,12 @@ public TSNode getNamedChild(int index) {
     return getNamedChildAt(index);
   }
 
+  /**
+   * Find the child node of the given node by field name.
+   *
+   * @param fieldName The field name.
+   * @return The found node.
+   */
   public TSNode getChildByFieldName(String fieldName) {
     final var bytes = fieldName.getBytes(StandardCharsets.UTF_8);
     return getChildByFieldName(bytes, bytes.length);
@@ -106,30 +124,20 @@ public String toString() {
    */
   public native TSNode getParent();
 
-  /**
-   * Get the child of the given node at the child index.
-   *
-   * @param index The index of the child.
-   * @return The child at the child index.
-   */
   private native TSNode getChildAt(int index);
 
-  /**
-   * Get the named child of the given node at the given index.
-   *
-   * @param index The index of the named child.
-   * @return The named child node at the given index.
-   */
   private native TSNode getNamedChildAt(int index);
 
+  private native TSNode getChildByFieldName(byte[] bytes, int length);
+
   /**
-   * Find the child node of the given node by field name.
+   * Get the field name for node's child at the given index, where zero represents * the first
+   * child.
    *
-   * @param bytes The field name of the child.
-   * @param length The length of `fieldName`.
-   * @return The found node.
+   * @param childIndex The index of the child.
+   * @return The field name for the child or <code>null</code>.
    */
-  private native TSNode getChildByFieldName(byte[] bytes, int length);
+  public native String getFieldNameForChild(int childIndex);
 
   /**
    * Get the number of children of the node.

android-tree-sitter/src/main/jniLibs/arm64-v8a/libts.so

@@ -64,6 +64,8 @@ public void testGetChildren() throws UnsupportedEncodingException {
         assertThat(isNull).isFalse();
 
         var function = root.getChild(0);
+        var fieldNameForChild = root.getFieldNameForChild(0);
+        assertThat(fieldNameForChild).isNull();
         start = function.getStartPoint();
         assertThat(0).isEqualTo(start.row);
         assertThat(0).isEqualTo(start.column);

android-tree-sitter/src/main/jniLibs/armeabi-v7a/libts.so

@@ -47,6 +47,18 @@ Java_com_itsaky_androidide_treesitter_TSNode_getChildByFieldName(
   return found;
 }
 
+JNIEXPORT jstring JNICALL Java_com_itsaky_androidide_treesitter_TSNode_getFieldNameForChild
+  (JNIEnv* env, jobject self, jint index) {
+    const char* fieldName = ts_node_field_name_for_child(_unmarshalNode(env, self), index);
+    if (fieldName == NULL) {
+      return NULL;
+    }
+    
+    jstring result = env->NewStringUTF(fieldName);
+    free((char*)fieldName);
+    return result;
+  }
+
 JNIEXPORT jstring JNICALL
 Java_com_itsaky_androidide_treesitter_TSNode_getNodeString(JNIEnv* env,
                                                            jobject self) {