Changing API name; Adding unit test and Rust bindings

cli/src/tests/node_test.rs

@@ -248,6 +248,25 @@ fn test_node_parent_of_child_by_field_name() {
     );
 }
 
+#[test]
+fn test_node_field_name_for_child() {
+    let mut parser = Parser::new();
+    parser.set_language(get_language("c")).unwrap();
+    let tree = parser.parse("x + y;", None).unwrap();
+    let translation_unit_node = tree.root_node();
+    let binary_expression_node = translation_unit_node
+                                 .named_child(0)
+                                 .unwrap()
+                                 .named_child(0)
+                                 .unwrap();
+
+    assert_eq!(binary_expression_node.field_name_for_child(0), Some("left"));
+    assert_eq!(binary_expression_node.field_name_for_child(1), Some("operator"));
+    assert_eq!(binary_expression_node.field_name_for_child(2), Some("right"));
+		// Negative test - Not a valid child index
+    assert_eq!(binary_expression_node.field_name_for_child(3), None);
+}
+
 #[test]
 fn test_node_child_by_field_name_with_extra_hidden_children() {
     let mut parser = Parser::new();

lib/binding_rust/bindings.rs

@@ -434,6 +434,11 @@ extern "C" {
     #[doc = " child."]
     pub fn ts_node_child(arg1: TSNode, arg2: u32) -> TSNode;
 }
+extern "C" {
+    #[doc = " Get the field name for node's child at the given index, where zero represents"]
+    #[doc = " the first child. Returns NULL, if no field is found."]
+    pub fn ts_node_field_name_for_child(arg1: TSNode, arg2: u32) -> *const ::std::os::raw::c_char;
+}
 extern "C" {
     #[doc = " Get the node\'s number of children."]
     pub fn ts_node_child_count(arg1: TSNode) -> u32;

lib/binding_rust/lib.rs

@@ -859,6 +859,18 @@ impl<'tree> Node<'tree> {
         Self::new(unsafe { ffi::ts_node_child_by_field_id(self.0, field_id) })
     }
 
+    /// Get the field name of this node's child at the given index.
+    pub fn field_name_for_child(&self, child_index: u32) -> Option<&'static str> {
+        unsafe {
+            let ptr = ffi::ts_node_field_name_for_child(self.0, child_index);
+            if ptr.is_null() {
+                None
+            } else {
+                Some(CStr::from_ptr(ptr).to_str().unwrap())
+            }
+        }
+    }
+
     /// Iterate over this node's children.
     ///
     /// A [TreeCursor] is used to retrieve the children efficiently. Obtain

lib/include/tree_sitter/api.h

@@ -488,10 +488,10 @@ TSNode ts_node_parent(TSNode);
 TSNode ts_node_child(TSNode, uint32_t);
 
 /**
- * Get the field_name for node's child at the given index, where zero represents
+ * Get the field name for node's child at the given index, where zero represents
  * the first child. Returns NULL, if no field is found.
  */
-const char *ts_node_child_field_name(TSNode, uint32_t);
+const char *ts_node_field_name_for_child(TSNode, uint32_t);
 
 /**
  * Get the node's number of children.