start impl rrdom

src/rrdom/tree-node.ts

@@ -0,0 +1,52 @@
+// tslint:disable-next-line: no-any
+export type AnyObject = { [key: string]: any; __rrdom__?: RRdomTreeNode };
+
+export class RRdomTreeNode implements AnyObject {
+  public parent: AnyObject | null = null;
+  public previousSibling: AnyObject | null = null;
+  public nextSibling: AnyObject | null = null;
+
+  public firstChild: AnyObject | null = null;
+  public lastChild: AnyObject | null = null;
+
+  // This value is incremented anytime a children is added or removed
+  public childrenVersion = 0;
+  // The last child object which has a cached index
+  public childIndexCachedUpTo: AnyObject | null = null;
+
+  /**
+   * This value represents the cached node index, as long as
+   * cachedIndexVersion matches with the childrenVersion of the parent
+   */
+  public cachedIndex = -1;
+  public cachedIndexVersion = NaN;
+
+  public get isAttached() {
+    return Boolean(this.parent || this.previousSibling || this.nextSibling);
+  }
+
+  public get hasChildren() {
+    return Boolean(this.firstChild);
+  }
+
+  public childrenChanged() {
+    // tslint:disable-next-line: no-bitwise
+    this.childrenVersion = (this.childrenVersion + 1) & 0xffffffff;
+    this.childIndexCachedUpTo = null;
+  }
+
+  public getCachedIndex(parentNode: AnyObject) {
+    if (this.cachedIndexVersion !== parentNode.childrenVersion) {
+      this.cachedIndexVersion = NaN;
+      // cachedIndex is no longer valid
+      return -1;
+    }
+
+    return this.cachedIndex;
+  }
+
+  public setCachedIndex(parentNode: AnyObject, index: number) {
+    this.cachedIndexVersion = parentNode.childrenVersion;
+    this.cachedIndex = index;
+  }
+}