add JSON formatter and editor from VS Code

src/edit.ts

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+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+'use strict';
+
+import { ParseError, Node, parseTree, findNodeAtLocation, JSONPath, Segment } from './main';
+import { Edit, FormattingOptions, format, applyEdit } from './format';
+
+export function removeProperty(text: string, path: JSONPath, formattingOptions: FormattingOptions): Edit[] {
+	return setProperty(text, path, void 0, formattingOptions);
+}
+
+export function setProperty(text: string, path: JSONPath, value: any, formattingOptions: FormattingOptions, getInsertionIndex?: (properties: string[]) => number): Edit[] {
+	let errors: ParseError[] = [];
+	let root = parseTree(text, errors);
+	let parent: Node = void 0;
+
+	let lastSegment: Segment = void 0;
+	while (path.length > 0) {
+		lastSegment = path.pop();
+		parent = findNodeAtLocation(root, path);
+		if (parent === void 0 && value !== void 0) {
+			if (typeof lastSegment === 'string') {
+				value = { [lastSegment]: value };
+			} else {
+				value = [value];
+			}
+		} else {
+			break;
+		}
+	}
+
+	if (!parent) {
+		// empty document
+		if (value === void 0) { // delete
+			throw new Error('Can not delete in empty document');
+		}
+		return withFormatting(text, { offset: root ? root.offset : 0, length: root ? root.length : 0, content: JSON.stringify(value) }, formattingOptions);
+	} else if (parent.type === 'object' && typeof lastSegment === 'string') {
+		let existing = findNodeAtLocation(parent, [lastSegment]);
+		if (existing !== void 0) {
+			if (value === void 0) { // delete
+				let propertyIndex = parent.children.indexOf(existing.parent);
+				let removeBegin: number;
+				let removeEnd = existing.parent.offset + existing.parent.length;
+				if (propertyIndex > 0) {
+					// remove the comma of the previous node
+					let previous = parent.children[propertyIndex - 1];
+					removeBegin = previous.offset + previous.length;
+				} else {
+					removeBegin = parent.offset + 1;
+					if (parent.children.length > 1) {
+						// remove the comma of the next node
+						let next = parent.children[1];
+						removeEnd = next.offset;
+					}
+				}
+				return withFormatting(text, { offset: removeBegin, length: removeEnd - removeBegin, content: '' }, formattingOptions);
+			} else {
+				// set value of existing property
+				return withFormatting(text, { offset: existing.offset, length: existing.length, content: JSON.stringify(value) }, formattingOptions);
+			}
+		} else {
+			if (value === void 0) { // delete
+				return []; // property does not exist, nothing to do
+			}
+			let newProperty = `${JSON.stringify(lastSegment)}: ${JSON.stringify(value)}`;
+			let index = getInsertionIndex ? getInsertionIndex(parent.children.map(p => p.children[0].value)) : parent.children.length;
+			let edit: Edit;
+			if (index > 0) {
+				let previous = parent.children[index - 1];
+				edit = { offset: previous.offset + previous.length, length: 0, content: ',' + newProperty };
+			} else if (parent.children.length === 0) {
+				edit = { offset: parent.offset + 1, length: 0, content: newProperty };
+			} else {
+				edit = { offset: parent.offset + 1, length: 0, content: newProperty + ',' };
+			}
+			return withFormatting(text, edit, formattingOptions);
+		}
+	} else if (parent.type === 'array' && typeof lastSegment === 'number') {
+		let insertIndex = lastSegment;
+		if (insertIndex === -1) {
+			// Insert
+			let newProperty = `${JSON.stringify(value)}`;
+			let edit: Edit;
+			if (parent.children.length === 0) {
+				edit = { offset: parent.offset + 1, length: 0, content: newProperty };
+			} else {
+				let previous = parent.children[parent.children.length - 1];
+				edit = { offset: previous.offset + previous.length, length: 0, content: ',' + newProperty };
+			}
+			return withFormatting(text, edit, formattingOptions);
+		} else {
+			if (value === void 0 && parent.children.length >= 0) {
+				//Removal
+				let removalIndex = lastSegment;
+				let toRemove = parent.children[removalIndex];
+				let edit: Edit;
+				if (parent.children.length === 1) {
+					// only item
+					edit = { offset: parent.offset + 1, length: parent.length - 2, content: '' };
+				} else if (parent.children.length - 1 === removalIndex) {
+					// last item
+					let previous = parent.children[removalIndex - 1];
+					let offset = previous.offset + previous.length;
+					let parentEndOffset = parent.offset + parent.length;
+					edit = { offset, length: parentEndOffset - 2 - offset, content: '' };
+				} else {
+					edit = { offset: toRemove.offset, length: parent.children[removalIndex + 1].offset - toRemove.offset, content: '' };
+				}
+				return withFormatting(text, edit, formattingOptions);
+			} else {
+				throw new Error('Array modification not supported yet');
+			}
+		}
+	} else {
+		throw new Error(`Can not add ${typeof lastSegment !== 'number' ? 'index' : 'property'} to parent of type ${parent.type}`);
+	}
+}
+
+function withFormatting(text: string, edit: Edit, formattingOptions: FormattingOptions): Edit[] {
+	// apply the edit
+	let newText = applyEdit(text, edit);
+
+	// format the new text
+	let begin = edit.offset;
+	let end = edit.offset + edit.content.length;
+	let edits = format(newText, { offset: begin, length: end - begin }, formattingOptions);
+
+	// apply the formatting edits and track the begin and end offsets of the changes
+	for (let i = edits.length - 1; i >= 0; i--) {
+		let edit = edits[i];
+		newText = applyEdit(newText, edit);
+		begin = Math.min(begin, edit.offset);
+		end = Math.max(end, edit.offset + edit.length);
+		end += edit.content.length - edit.length;
+	}
+	// create a single edit with all changes
+	let editLength = text.length - (newText.length - end) - begin;
+	return [{ offset: begin, length: editLength, content: newText.substring(begin, end) }];
+}

src/format.ts

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+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+'use strict';
+
+import * as Json from './main';
+
+export interface FormattingOptions {
+	/**
+	 * If indentation is based on spaces (`insertSpaces` = true), then what is the number of spaces that make an indent?
+	 */
+	tabSize: number;
+	/**
+	 * Is indentation based on spaces?
+	 */
+	insertSpaces: boolean;
+	/**
+	 * The default end of line line character
+	 */
+	eol: string;
+}
+
+export interface Edit {
+	offset: number;
+	length: number;
+	content: string;
+}
+
+export function applyEdit(text: string, edit: Edit): string {
+	return text.substring(0, edit.offset) + edit.content + text.substring(edit.offset + edit.length);
+}
+
+export function applyEdits(text: string, edits: Edit[]): string {
+	for (let i = edits.length - 1; i >= 0; i--) {
+		text = applyEdit(text, edits[i]);
+	}
+	return text;
+}
+
+export function format(documentText: string, range: { offset: number, length: number }, options: FormattingOptions): Edit[] {
+	let initialIndentLevel: number;
+	let value: string;
+	let rangeStart: number;
+	let rangeEnd: number;
+	if (range) {
+		rangeStart = range.offset;
+		rangeEnd = rangeStart + range.length;
+		while (rangeStart > 0 && !isEOL(documentText, rangeStart - 1)) {
+			rangeStart--;
+		}
+		let scanner = Json.createScanner(documentText, true);
+		scanner.setPosition(rangeEnd);
+		scanner.scan();
+		rangeEnd = scanner.getPosition();
+
+		value = documentText.substring(rangeStart, rangeEnd);
+		initialIndentLevel = computeIndentLevel(value, 0, options);
+	} else {
+		value = documentText;
+		rangeStart = 0;
+		rangeEnd = documentText.length;
+		initialIndentLevel = 0;
+	}
+	let eol = getEOL(options, documentText);
+
+	let lineBreak = false;
+	let indentLevel = 0;
+	let indentValue: string;
+	if (options.insertSpaces) {
+		indentValue = repeat(' ', options.tabSize);
+	} else {
+		indentValue = '\t';
+	}
+
+	let scanner = Json.createScanner(value, false);
+
+	function newLineAndIndent(): string {
+		return eol + repeat(indentValue, initialIndentLevel + indentLevel);
+	}
+	function scanNext(): Json.SyntaxKind {
+		let token = scanner.scan();
+		lineBreak = false;
+		while (token === Json.SyntaxKind.Trivia || token === Json.SyntaxKind.LineBreakTrivia) {
+			lineBreak = lineBreak || (token === Json.SyntaxKind.LineBreakTrivia);
+			token = scanner.scan();
+		}
+		return token;
+	}
+	let editOperations: Edit[] = [];
+	function addEdit(text: string, startOffset: number, endOffset: number) {
+		if (documentText.substring(startOffset, endOffset) !== text) {
+			editOperations.push({ offset: startOffset, length: endOffset - startOffset, content: text });
+		}
+	}
+
+	let firstToken = scanNext();
+	if (firstToken !== Json.SyntaxKind.EOF) {
+		let firstTokenStart = scanner.getTokenOffset() + rangeStart;
+		let initialIndent = repeat(indentValue, initialIndentLevel);
+		addEdit(initialIndent, rangeStart, firstTokenStart);
+	}
+
+	while (firstToken !== Json.SyntaxKind.EOF) {
+		let firstTokenEnd = scanner.getTokenOffset() + scanner.getTokenLength() + rangeStart;
+		let secondToken = scanNext();
+
+		let replaceContent = '';
+		while (!lineBreak && (secondToken === Json.SyntaxKind.LineCommentTrivia || secondToken === Json.SyntaxKind.BlockCommentTrivia)) {
+			// comments on the same line: keep them on the same line, but ignore them otherwise
+			let commentTokenStart = scanner.getTokenOffset() + rangeStart;
+			addEdit(' ', firstTokenEnd, commentTokenStart);
+			firstTokenEnd = scanner.getTokenOffset() + scanner.getTokenLength() + rangeStart;
+			replaceContent = secondToken === Json.SyntaxKind.LineCommentTrivia ? newLineAndIndent() : '';
+			secondToken = scanNext();
+		}
+
+		if (secondToken === Json.SyntaxKind.CloseBraceToken) {
+			if (firstToken !== Json.SyntaxKind.OpenBraceToken) {
+				indentLevel--;
+				replaceContent = newLineAndIndent();
+			}
+		} else if (secondToken === Json.SyntaxKind.CloseBracketToken) {
+			if (firstToken !== Json.SyntaxKind.OpenBracketToken) {
+				indentLevel--;
+				replaceContent = newLineAndIndent();
+			}
+		} else if (secondToken !== Json.SyntaxKind.EOF) {
+			switch (firstToken) {
+				case Json.SyntaxKind.OpenBracketToken:
+				case Json.SyntaxKind.OpenBraceToken:
+					indentLevel++;
+					replaceContent = newLineAndIndent();
+					break;
+				case Json.SyntaxKind.CommaToken:
+				case Json.SyntaxKind.LineCommentTrivia:
+					replaceContent = newLineAndIndent();
+					break;
+				case Json.SyntaxKind.BlockCommentTrivia:
+					if (lineBreak) {
+						replaceContent = newLineAndIndent();
+					} else {
+						// symbol following comment on the same line: keep on same line, separate with ' '
+						replaceContent = ' ';
+					}
+					break;
+				case Json.SyntaxKind.ColonToken:
+					replaceContent = ' ';
+					break;
+				case Json.SyntaxKind.NullKeyword:
+				case Json.SyntaxKind.TrueKeyword:
+				case Json.SyntaxKind.FalseKeyword:
+				case Json.SyntaxKind.NumericLiteral:
+					if (secondToken === Json.SyntaxKind.NullKeyword || secondToken === Json.SyntaxKind.FalseKeyword || secondToken === Json.SyntaxKind.NumericLiteral) {
+						replaceContent = ' ';
+					}
+					break;
+			}
+			if (lineBreak && (secondToken === Json.SyntaxKind.LineCommentTrivia || secondToken === Json.SyntaxKind.BlockCommentTrivia)) {
+				replaceContent = newLineAndIndent();
+			}
+
+		}
+		let secondTokenStart = scanner.getTokenOffset() + rangeStart;
+		addEdit(replaceContent, firstTokenEnd, secondTokenStart);
+		firstToken = secondToken;
+	}
+	return editOperations;
+}
+
+function repeat(s: string, count: number): string {
+	let result = '';
+	for (let i = 0; i < count; i++) {
+		result += s;
+	}
+	return result;
+}
+
+function computeIndentLevel(content: string, offset: number, options: FormattingOptions): number {
+	let i = 0;
+	let nChars = 0;
+	let tabSize = options.tabSize || 4;
+	while (i < content.length) {
+		let ch = content.charAt(i);
+		if (ch === ' ') {
+			nChars++;
+		} else if (ch === '\t') {
+			nChars += tabSize;
+		} else {
+			break;
+		}
+		i++;
+	}
+	return Math.floor(nChars / tabSize);
+}
+
+function getEOL(options: FormattingOptions, text: string): string {
+	for (let i = 0; i < text.length; i++) {
+		let ch = text.charAt(i);
+		if (ch === '\r') {
+			if (i + 1 < text.length && text.charAt(i + 1) === '\n') {
+				return '\r\n';
+			}
+			return '\r';
+		} else if (ch === '\n') {
+			return '\n';
+		}
+	}
+	return (options && options.eol) || '\n';
+}
+
+function isEOL(text: string, offset: number) {
+	return '\r\n'.indexOf(text.charAt(offset)) !== -1;
+}