feat(tree): Add Cdk Tree component (#7984)

* Add Cdk Tree component

* Put tree control in control folder. Removed NestedNode FlatNode types
and add getLevel getChildren isExpandable in TreeControl.

* Use static varaible to pass node data

* fix lint

* another round

* update documents according to comments

Author: tinayuangao

.github/CODEOWNERS

@@ -69,6 +69,7 @@
 /src/cdk/stepper/**                                @mmalerba
 /src/cdk/table/**                                  @andrewseguin
 /src/cdk/testing/**                                @devversion
+/src/cdk/tree/**                                   @tinayuangao
 
 # Moment adapter package
 /src/material-moment-adapter/**                    @mmalerba

src/cdk/collections/public-api.ts

@@ -14,3 +14,4 @@ export {
   UniqueSelectionDispatcherListener,
   UNIQUE_SELECTION_DISPATCHER_PROVIDER,
 } from './unique-selection-dispatcher';
+export * from './tree-adapter';

src/cdk/collections/tree-adapter.ts

@@ -0,0 +1,31 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+import {SelectionModel} from './selection';
+
+
+/**
+ * Interface for a class that can flatten hierarchical structured data and re-expand the flattened
+ * data back into its original structure. Should be used in conjunction with the cdk-tree.
+ */
+export interface TreeDataNodeFlattener<T> {
+  /** Transforms a set of hierarchical structured data into a flattened data array. */
+  flattenNodes(structuredData: any[]): T[];
+
+  /**
+   * Expands a flattened array of data into its hierarchical form using the provided expansion
+   * model.
+   */
+  expandFlattenedNodes(nodes: T[], expansionModel: SelectionModel<T>): T[];
+
+  /**
+   * Put node descendants of node in array.
+   * If `onlyExpandable` is true, then only process expandable descendants.
+   */
+  nodeDescendents(node: T, nodes: T[], onlyExpandable: boolean);
+}

src/cdk/tree/control/base-tree-control.ts

@@ -0,0 +1,84 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+import {SelectionModel} from '@angular/cdk/collections';
+import {Observable} from 'rxjs/Observable';
+import {TreeControl} from './tree-control';
+
+/** Base tree control. It has basic toggle/expand/collapse operations on a single data node. */
+export abstract class BaseTreeControl<T> implements TreeControl<T> {
+
+  /** Gets a list of descendent data nodes of a subtree rooted at given data node recursively. */
+  abstract getDescendants(dataNode: T): T[];
+
+  /** Expands all data nodes in the tree. */
+  abstract expandAll(): void;
+
+  /** Saved data node for `expandAll` action. */
+  dataNodes: T[];
+
+  /** A selection model with multi-selection to track expansion status. */
+  expansionModel: SelectionModel<T> = new SelectionModel<T>(true);
+
+  /** Get depth of a given data node, return the level number. This is for flat tree node. */
+  getLevel: (dataNode: T) => number;
+
+  /**
+   * Whether the data node is expandable. Returns true if expandable.
+   * This is for flat tree node.
+   */
+  isExpandable: (dataNode: T) => boolean;
+
+  /** Gets a stream that emits whenever the given data node's children change. */
+  getChildren: (dataNode: T) => Observable<T[]>;
+
+  /** Toggles one single data node's expanded/collapsed state. */
+  toggle(dataNode: T): void {
+    this.expansionModel.toggle(dataNode);
+  }
+
+  /** Expands one single data node. */
+  expand(dataNode: T): void {
+    this.expansionModel.select(dataNode);
+  }
+
+  /** Collapses one single data node. */
+  collapse(dataNode: T): void {
+    this.expansionModel.deselect(dataNode);
+  }
+
+  /** Whether a given data node is expanded or not. Returns true if the data node is expanded. */
+  isExpanded(dataNode: T): boolean {
+    return this.expansionModel.isSelected(dataNode);
+  }
+
+  /** Toggles a subtree rooted at `node` recursively. */
+  toggleDescendants(dataNode: T): void {
+    this.expansionModel.isSelected(dataNode)
+        ? this.collapseDescendants(dataNode)
+        : this.expandDescendants(dataNode);
+  }
+
+  /** Collapse all dataNodes in the tree. */
+  collapseAll(): void {
+    this.expansionModel.clear();
+  }
+
+  /** Expands a subtree rooted at given data node recursively. */
+  expandDescendants(dataNode: T): void {
+    let toBeProcessed = [dataNode];
+    toBeProcessed.push(...this.getDescendants(dataNode));
+    this.expansionModel.select(...toBeProcessed);
+  }
+
+  /** Collapses a subtree rooted at given data node recursively. */
+  collapseDescendants(dataNode: T): void {
+    let toBeProcessed = [dataNode];
+    toBeProcessed.push(...this.getDescendants(dataNode));
+    this.expansionModel.deselect(...toBeProcessed);
+  }
+}

src/cdk/tree/control/flat-tree-control.spec.ts

@@ -0,0 +1,188 @@
+import {FlatTreeControl} from './flat-tree-control';
+
+describe('CdkFlatTreeControl', () => {
+  let treeControl: FlatTreeControl<TestData>;
+  let getLevel = (node: TestData) => node.level;
+  let isExpandable = (node: TestData) => node.children && node.children.length > 0;
+
+  beforeEach(() => {
+    treeControl = new FlatTreeControl<TestData>(getLevel, isExpandable);
+  });
+
+  describe('base tree control actions', () => {
+    it('should be able to expand and collapse dataNodes', () => {
+      const nodes = generateData(10, 4);
+      const secondNode = nodes[1];
+      const sixthNode = nodes[5];
+      treeControl.dataNodes = nodes;
+
+      treeControl.expand(secondNode);
+
+
+      expect(treeControl.isExpanded(secondNode))
+          .toBeTruthy('Expect second node to be expanded');
+      expect(treeControl.expansionModel.selected)
+          .toContain(secondNode, 'Expect second node in expansionModel');
+      expect(treeControl.expansionModel.selected.length)
+          .toBe(1, 'Expect only second node in expansionModel');
+
+      treeControl.toggle(sixthNode);
+
+      expect(treeControl.isExpanded(secondNode))
+          .toBeTruthy('Expect second node to stay expanded');
+      expect(treeControl.isExpanded(sixthNode))
+          .toBeTruthy('Expect sixth node to be expanded');
+      expect(treeControl.expansionModel.selected)
+          .toContain(sixthNode, 'Expect sixth node in expansionModel');
+      expect(treeControl.expansionModel.selected)
+          .toContain(secondNode, 'Expect second node in expansionModel');
+      expect(treeControl.expansionModel.selected.length)
+          .toBe(2, 'Expect two dataNodes in expansionModel');
+
+      treeControl.collapse(seconNode);
+
+      expect(treeControl.isExpanded(secondNode))
+          .toBeFalsy('Expect second node to be collapsed');
+      expect(treeControl.expansionModel.selected.length)
+          .toBe(1, 'Expect one node in expansionModel');
+      expect(treeControl.isExpanded(sixthNode)).toBeTruthy('Expect sixth node to stay expanded');
+      expect(treeControl.expansionModel.selected)
+          .toContain(sixthNode, 'Expect sixth node in expansionModel');
+    });
+
+    it('should return correct expandable values', () => {
+      const nodes = generateData(10, 4);
+      treeControl.dataNodes = nodes;
+
+      for (let i = 0; i < 10; i++) {
+        expect(treeControl.isExpandable(nodes[i]))
+          .toBeTruthy(`Expect node[${i}] to be expandable`);
+
+        for (let j = 0; j < 4; j++) {
+          expect(treeControl.isExpandable(nodes[i].children[j]))
+            .toBeFalsy(`Expect node[${i}]'s child[${j}] to be not expandable`);
+        }
+      }
+    });
+
+    it('should return correct levels', () => {
+      const numNodes = 10;
+      const numChildren = 4;
+      const numGrandChildren = 2;
+      const nodes = generateData(numNodes, numChildren, numGrandChildren);
+      treeControl.dataNodes = nodes;
+
+      for (let i = 0; i < numNodes; i++) {
+        expect(treeControl.getLevel(nodes[i]))
+          .toBe(1, `Expec node[${i}]'s level to be 1`);
+
+        for (let j = 0; j < numChildren; j++) {
+          expect(treeControl.getLevel(nodes[i].children[j]))
+            .toBe(2, `Expect node[${i}]'s child[${j}] to be not expandable`);
+
+          for (let k = 0; k < numGrandChildren; k++) {
+            expect(treeControl.getLevel(nodes[i].children[j].children[k]))
+              .toBe(3, `Expect node[${i}]'s child[${j}] to be not expandable`);
+          }
+        }
+      }
+    });
+
+    it('should toggle descendants correctly', () => {
+      const numNodes = 10;
+      const numChildren = 4;
+      const numGrandChildren = 2;
+      const nodes = generateData(numNodes, numChildren, numGrandChildren);
+
+      let data = [];
+      flatten(nodes, data);
+      treeControl.dataNodes = data;
+
+      treeControl.expandDescendants(nodes[1]);
+
+      const expandedNodesNum = 1 + numChildren + numChildren * numGrandChildren;
+      expect(treeControl.expansionModel.selected.length)
+          .toBe(expandedNodesNum, `Expect expanded ${expandedNodesNum} nodes`);
+
+      expect(treeControl.isExpanded(nodes[1])).toBeTruthy('Expect second node to be expanded');
+      for (let i = 0; i < numChildren; i++) {
+
+        expect(treeControl.isExpanded(nodes[1].children[i]))
+          .toBeTruthy(`Expect second node's children to be expanded`);
+        for (let j = 0; j < numGrandChildren; j++) {
+          expect(treeControl.isExpanded(nodes[1].children[i].children[j]))
+              .toBeTruthy(`Expect second node grand children to be not expanded`);
+        }
+      }
+
+    });
+
+    it('should be able to expand/collapse all the dataNodes', () => {
+      const numNodes = 10;
+      const numChildren = 4;
+      const numGrandChildren = 2;
+      const nodes = generateData(numNodes, numChildren, numGrandChildren);
+      let data = [];
+      flatten(nodes, data);
+      treeControl.dataNodes = data;
+
+      treeControl.expandDescendants(nodes[1]);
+
+      treeControl.collapseAll();
+
+      expect(treeControl.expansionModel.selected.length).toBe(0, `Expect no expanded nodes`);
+
+      treeControl.expandAll();
+
+      const totalNumber = numNodes + numNodes * numChildren
+          + numNodes * numChildren * numGrandChildren;
+      expect(treeControl.expansionModel.selected.length)
+        .toBe(totalNumber, `Expect ${totalNumber} expanded nodes`);
+    });
+  });
+});
+
+export class TestData {
+  a: string;
+  b: string;
+  c: string;
+  level: number;
+  children: TestData[];
+
+  constructor(a: string, b: string, c: string, level: number = 1, children: TestData[] = []) {
+    this.a = a;
+    this.b = b;
+    this.c = c;
+    this.level = level;
+    this.children = children;
+  }
+}
+
+function generateData(dataLength: number, childLength: number, grandChildLength: number = 0)
+    : TestData[] {
+  let data = <any>[];
+  let nextIndex = 0;
+  for (let i = 0; i < dataLength; i++) {
+    let children = <any>[];
+    for (let j = 0; j < childLength; j++) {
+      let grandChildren = <any>[];
+      for (let k = 0; k < grandChildLength; k++) {
+        grandChildren.push(new TestData(`a_${nextIndex}`, `b_${nextIndex}`, `c_${nextIndex++}`, 3));
+      }
+      children.push(
+          new TestData(`a_${nextIndex}`, `b_${nextIndex}`, `c_${nextIndex++}`, 2, grandChildren));
+    }
+    data.push(new TestData(`a_${nextIndex}`, `b_${nextIndex}`, `c_${nextIndex++}`, 1, children));
+  }
+  return data;
+}
+
+function flatten(nodes: TestData[], data: TestData[]) {
+  for (let node of nodes) {
+    data.push(node);
+
+    if (node.children && node.children.length > 0) {
+      flatten(node.children, data);
+    }
+  }
+}

src/cdk/tree/control/flat-tree-control.ts

@@ -0,0 +1,53 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+import {BaseTreeControl} from './base-tree-control';
+
+/** Flat tree control. Able to expand/collapse a subtree recursively for flattened tree. */
+export class FlatTreeControl<T> extends BaseTreeControl<T> {
+
+  /** Construct with flat tree data node functions getLevel and isExpandable. */
+  constructor(public getLevel: (dataNode: T) => number,
+              public isExpandable: (dataNode: T) => boolean) {
+    super();
+  }
+
+  /**
+   * Gets a list of the data node's subtree of descendent data nodes.
+   *
+   * To make this working, the `dataNodes` of the TreeControl must be flattened tree nodes
+   * with correct levels.
+   */
+  getDescendants(dataNode: T): T[] {
+    const startIndex = this.dataNodes.indexOf(dataNode);
+    const results: T[] = [];
+
+    // Goes through flattened tree nodes in the `dataNodes` array, and get all descendants.
+    // The level of descendants of a tree node must be greater than the level of the given
+    // tree node. 
+    // If we reach a node whose level is equal to the level of the tree node, we hit a sibling.
+    // If we reach a node whose level is greater than the level of the tree node, we hit a 
+    // sibling of an ancestor. 
+    for (let i = startIndex + 1;
+        i < this.dataNodes.length && this.getLevel(dataNode) < this.getLevel(this.dataNodes[i]);
+        i++) {
+      results.push(this.dataNodes[i]);
+    }
+    return results;
+  }
+
+  /**
+   * Expands all data nodes in the tree.
+   *
+   * To make this working, the `dataNodes` variable of the TreeControl must be set to all flattened
+   * data nodes of the tree.
+   */
+  expandAll(): void {
+    this.expansionModel.select(...this.dataNodes);
+  }
+}