feat: 🎸 implement child removal function for tree

Author: Xanonymous-GitHub

core/src/main/kotlin/tw/xcc/gumtree/model/BasicTree.kt

@@ -68,7 +68,7 @@ abstract class BasicTree<T> : Tree, Traversable<T> where T : BasicTree<T> {
             }
         }
 
-    fun addChild(child: T) {
+    open fun addChild(child: T) {
         synchronized(this) {
             val newChildrenMap = childrenMap.get()
             newChildrenMap[newChildrenMap.size] = child.also { it.setParentTo(self) }

core/src/main/kotlin/tw/xcc/gumtree/model/GumTree.kt

@@ -76,6 +76,23 @@ open class GumTree(
         child: GumTree
     ) = insertChildAtImpl(pos, child)
 
+    open fun tryRemoveChild(child: GumTree): Boolean =
+        synchronized(this) {
+            val pos = child.positionOfParent
+            if (pos == -1) {
+                return false
+            }
+
+            val children = childrenMap.get()
+            val removedChild = children.remove(pos) ?: return false
+
+            removedChild.setParentTo(null)
+            removedChild._positionOfParent.set(-1)
+            childrenMap.set(children)
+
+            return true
+        }
+
     open fun toNewFrozen(): GumTreeView =
         synchronized(this) {
             val children = childrenMap.get()
@@ -88,6 +105,11 @@ open class GumTree(
 
     infix fun hasSameLabelAs(other: GumTree): Boolean = label == other.label
 
+    override fun addChild(child: GumTree) {
+        super.addChild(child)
+        child._positionOfParent.set(childCount() - 1)
+    }
+
     final override infix fun isIsomorphicTo(other: GumTree): Boolean = isIsomorphicTo(this, other)
 
     final override infix fun isIsoStructuralTo(other: GumTree): Boolean = isIsoStructuralTo(this, other)

core/src/main/kotlin/tw/xcc/gumtree/model/GumTreeView.kt

@@ -41,6 +41,14 @@ class GumTreeView private constructor(target: GumTree) : GumTree(target) {
         throw NoSuchMethodException("calling this method in GumTreeView is not allowed")
     }
 
+    override fun addChild(child: GumTree) {
+        throw NoSuchMethodException("calling this method in GumTreeView is not allowed")
+    }
+
+    override fun tryRemoveChild(child: GumTree): Boolean {
+        throw NoSuchMethodException("calling this method in GumTreeView is not allowed")
+    }
+
     override fun inOrdered(): List<GumTree> = throw NotImplementedError()
 
     companion object {

core/src/test/kotlin/GumTreeTest.kt

@@ -142,4 +142,20 @@ internal class GumTreeTest {
         assertEquals(child.id, frozen.childAt(0)?.id)
         assertTrue(child !== frozen.childAt(0))
     }
+
+    @Test
+    fun `test tryRemoveChild`() {
+        val child = GumTree(TreeType.empty(), "child")
+        givenTree.addChild(child)
+        val actualResult = givenTree.tryRemoveChild(child)
+        assertTrue(actualResult)
+        assertEquals(0, givenTree.childCount())
+    }
+
+    @Test
+    fun `test tryRemoveChild with non-child`() {
+        val child = GumTree(TreeType.empty(), "child")
+        val actualResult = givenTree.tryRemoveChild(child)
+        assertFalse(actualResult)
+    }
 }