planning

node_modules/react-dnd-html5-backend/lib/EnterLeaveCounter.js

@@ -0,0 +1,23 @@
+import { union, without } from './utils/js_utils';
+export class EnterLeaveCounter {
+    entered = [];
+    isNodeInDocument;
+    constructor(isNodeInDocument) {
+        this.isNodeInDocument = isNodeInDocument;
+    }
+    enter(enteringNode) {
+        const previousLength = this.entered.length;
+        const isNodeEntered = (node) => this.isNodeInDocument(node) &&
+            (!node.contains || node.contains(enteringNode));
+        this.entered = union(this.entered.filter(isNodeEntered), [enteringNode]);
+        return previousLength === 0 && this.entered.length > 0;
+    }
+    leave(leavingNode) {
+        const previousLength = this.entered.length;
+        this.entered = without(this.entered.filter(this.isNodeInDocument), leavingNode);
+        return previousLength > 0 && this.entered.length === 0;
+    }
+    reset() {
+        this.entered = [];
+    }
+}