Merge commit 'be3e8236086165e5e45a5a10783823874b3f3ebd' as 'lib/vscode'

lib/vscode/extensions/markdown-language-features/src/tableOfContentsProvider.ts

@@ -0,0 +1,118 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import * as vscode from 'vscode';
+import { MarkdownEngine } from './markdownEngine';
+import { Slug, githubSlugifier } from './slugify';
+
+export interface TocEntry {
+	readonly slug: Slug;
+	readonly text: string;
+	readonly level: number;
+	readonly line: number;
+	readonly location: vscode.Location;
+}
+
+export interface SkinnyTextLine {
+	text: string;
+}
+
+export interface SkinnyTextDocument {
+	readonly uri: vscode.Uri;
+	readonly version: number;
+	readonly lineCount: number;
+
+	lineAt(line: number): SkinnyTextLine;
+	getText(): string;
+}
+
+export class TableOfContentsProvider {
+	private toc?: TocEntry[];
+
+	public constructor(
+		private engine: MarkdownEngine,
+		private document: SkinnyTextDocument
+	) { }
+
+	public async getToc(): Promise<TocEntry[]> {
+		if (!this.toc) {
+			try {
+				this.toc = await this.buildToc(this.document);
+			} catch (e) {
+				this.toc = [];
+			}
+		}
+		return this.toc;
+	}
+
+	public async lookup(fragment: string): Promise<TocEntry | undefined> {
+		const toc = await this.getToc();
+		const slug = githubSlugifier.fromHeading(fragment);
+		return toc.find(entry => entry.slug.equals(slug));
+	}
+
+	private async buildToc(document: SkinnyTextDocument): Promise<TocEntry[]> {
+		const toc: TocEntry[] = [];
+		const tokens = await this.engine.parse(document);
+
+		const existingSlugEntries = new Map<string, { count: number }>();
+
+		for (const heading of tokens.filter(token => token.type === 'heading_open')) {
+			const lineNumber = heading.map[0];
+			const line = document.lineAt(lineNumber);
+
+			let slug = githubSlugifier.fromHeading(line.text);
+			const existingSlugEntry = existingSlugEntries.get(slug.value);
+			if (existingSlugEntry) {
+				++existingSlugEntry.count;
+				slug = githubSlugifier.fromHeading(slug.value + '-' + existingSlugEntry.count);
+			} else {
+				existingSlugEntries.set(slug.value, { count: 0 });
+			}
+
+			toc.push({
+				slug,
+				text: TableOfContentsProvider.getHeaderText(line.text),
+				level: TableOfContentsProvider.getHeaderLevel(heading.markup),
+				line: lineNumber,
+				location: new vscode.Location(document.uri,
+					new vscode.Range(lineNumber, 0, lineNumber, line.text.length))
+			});
+		}
+
+		// Get full range of section
+		return toc.map((entry, startIndex): TocEntry => {
+			let end: number | undefined = undefined;
+			for (let i = startIndex + 1; i < toc.length; ++i) {
+				if (toc[i].level <= entry.level) {
+					end = toc[i].line - 1;
+					break;
+				}
+			}
+			const endLine = end ?? document.lineCount - 1;
+			return {
+				...entry,
+				location: new vscode.Location(document.uri,
+					new vscode.Range(
+						entry.location.range.start,
+						new vscode.Position(endLine, document.lineAt(endLine).text.length)))
+			};
+		});
+	}
+
+	private static getHeaderLevel(markup: string): number {
+		if (markup === '=') {
+			return 1;
+		} else if (markup === '-') {
+			return 2;
+		} else { // '#', '##', ...
+			return markup.length;
+		}
+	}
+
+	private static getHeaderText(header: string): string {
+		return header.replace(/^\s*#+\s*(.*?)\s*#*$/, (_, word) => word.trim());
+	}
+}