json: Add findNodeAtLocation

src/vs/base/common/json.ts

@@ -931,6 +931,49 @@ export function parseTree(text:string, errors: ParseError[] = [], options?: Pars
 	return result;
 }
 
+export function findNodeAtLocation(root: Node, segments: Segment[]) : Node {
+	let node = root;
+	for (let segment of segments) {
+		if (typeof segment === 'string') {
+			if (node.type !== 'object') {
+				return void 0;
+			}
+			let found = false;
+			for (let propertyNode of node.children) {
+				if (propertyNode.children[0].value === segment) {
+					node = propertyNode.children[1];
+					found = true;
+					break;
+				}
+			}
+			if (!found) {
+				return void 0;
+			}
+		} else {
+			let index = <number> segment;
+			if (node.type !== 'array' || index < 0 || index >= node.children.length) {
+				return void 0;
+			}
+			node = node.children[index];
+		}
+	}
+	return node;
+}
+
+export function getNodeValue(node: Node) : any {
+	if (node.type === 'array') {
+		return node.children.map(getNodeValue);
+	} else if (node.type === 'object') {
+		let obj = {};
+		for (let prop of node.children) {
+			obj[prop.children[0].value] = getNodeValue(prop.children[1]);
+		}
+		return obj;
+	}
+	return node.value;
+}
+
+
 /**
  * Parses the given text and invokes the visitor functions for each object, array and literal reached.
  */

src/vs/base/test/common/json.test.ts

@@ -5,7 +5,8 @@
 'use strict';
 
 import * as assert from 'assert';
-import { SyntaxKind, createScanner, parse, getLocation, Node, ParseError, parseTree, ParseErrorCode, getParseErrorMessage, ParseOptions, Segment } from 'vs/base/common/json';
+import { SyntaxKind, createScanner, parse, getLocation, Node, ParseError, parseTree, ParseErrorCode,
+	getParseErrorMessage, ParseOptions, Segment, findNodeAtLocation, getNodeValue } from 'vs/base/common/json';
 
 function assertKinds(text:string, ...kinds:SyntaxKind[]):void {
 	var _json = createScanner(text);
@@ -54,6 +55,11 @@ function assertTree(input:string, expected:any) : void {
 	assert.deepEqual(actual, expected);
 }
 
+function assertNodeAtLocation(input:Node, segments: Segment[], expected: any) {
+	let actual = findNodeAtLocation(input, segments);
+	assert.deepEqual(actual ? getNodeValue(actual) : void 0, expected);
+}
+
 
 function assertLocation(input:string, expectedSegments: Segment[], expectedNodeType: string, expectedCompleteProperty: boolean) : void {
 	var errors : {error: ParseErrorCode}[] = [];
@@ -304,4 +310,18 @@ suite('JSON', () => {
 			]}
 		);
 	});
+
+	test('tree: find location', () => {
+		let root = parseTree('{ "key1": { "key11": [ "val111", "val112" ] }, "key2": [ { "key21": false, "key22": 221 }, null, [{}] ] }');
+		assertNodeAtLocation(root, [ "key1"], { key11: [ 'val111', 'val112' ]});
+		assertNodeAtLocation(root, [ "key1", "key11"], [ 'val111', 'val112' ]);
+		assertNodeAtLocation(root, [ "key1", "key11", 0], 'val111');
+		assertNodeAtLocation(root, [ "key1", "key11", 1], 'val112');
+		assertNodeAtLocation(root, [ "key1", "key11", 2], void 0);
+		assertNodeAtLocation(root, [ "key2", 0, "key21"], false);
+		assertNodeAtLocation(root, [ "key2", 0, "key22"], 221);
+		assertNodeAtLocation(root, [ "key2", 1], null);
+		assertNodeAtLocation(root, [ "key2", 2], [{}]);
+		assertNodeAtLocation(root, [ "key2", 2, 0], {});
+	});
 });