Evaluate Math Expression using new Emmet

extensions/emmet/src/bufferStream.ts

@@ -15,7 +15,7 @@ export class DocumentStreamReader {
 	private document: TextDocument;
 	private start: Position;
 	private _eof: Position;
-	private pos: Position;
+	public pos: Position;
 	private _eol: string;
 
 	/**

extensions/emmet/src/evaluateMathExpression.ts

@@ -0,0 +1,32 @@
+/*---------------------------------------------------------------------------------------------
+ *  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 evaluate from '@emmetio/math-expression';
+import { DocumentStreamReader } from './bufferStream';
+
+export function evaluateMathExpression() {
+	let editor = vscode.window.activeTextEditor;
+	if (!editor) {
+		vscode.window.showInformationMessage('No editor is active');
+		return;
+	}
+	const stream = new DocumentStreamReader(editor.document);
+	editor.edit(editBuilder => {
+		editor.selections.forEach(selection => {
+			const pos = selection.isReversed ? selection.anchor : selection.active;
+			stream.pos = pos;
+
+			try {
+				const result = String(evaluate(stream, true));
+				editBuilder.replace(new vscode.Range(stream.pos, pos), result);
+			} catch (err) {
+				// Ignore error since most likely it’s because of non-math expression
+				console.warn('Math evaluation error', err);
+			}
+		});
+	});
+
+}

extensions/emmet/src/extension.ts

@@ -15,6 +15,7 @@ import { mergeLines } from './mergeLines';
 import { toggleComment } from './toggleComment';
 import { fetchEditPoint } from './editPoint';
 import { fetchSelectItem } from './selectItem';
+import { evaluateMathExpression } from './evaluateMathExpression';
 import { LANGUAGE_MODES, getMappedModes } from './util';
 import { updateExtensionsPath } from 'vscode-emmet-helper';
 
@@ -91,6 +92,10 @@ export function activate(context: vscode.ExtensionContext) {
 		fetchSelectItem('prev');
 	}));
 
+	context.subscriptions.push(vscode.commands.registerCommand('emmet.evaluateMathExpression', () => {
+		evaluateMathExpression();
+	}));
+
 	updateExtensionsPath();
 	context.subscriptions.push(vscode.workspace.onDidChangeConfiguration(() => {
 		updateExtensionsPath();