VSCode decoration API

extension.ts

'use strict';
// The module 'vscode' contains the VS Code extensibility API
// Import the module and reference it with the alias vscode in your code below
import { window, commands, ExtensionContext, Range, Position, TextEditor, workspace, DecorationOptions } from 'vscode';

const decorationType = window.createTextEditorDecorationType({ })


function addDecorations(e: TextEditor) {
    try {
    const params = {
        42: 'someIntParam',
        foo: 'someStringParam'
    };
    const decorations: DecorationOptions[] = []
    for (let lineNumber = 0; lineNumber < e.document.lineCount; lineNumber++) {
        const lineText = e.document.lineAt(lineNumber).text;
        const decs = Object.keys(params).reduce((acc: DecorationOptions[], param) => {
            const index = lineText.indexOf(param)
            if (index !== -1) {
                return acc.concat({
                    renderOptions: { before: { contentText: params[param] + ' = ', color: 'grey' }, },
                    range: new Range(new Position(lineNumber, index), new Position(lineNumber, index + param.length))
                })
            }
            return acc
        }, [])
        decs.forEach(d => decorations.push(d))
    }
    e.setDecorations(decorationType, decorations)
} catch (e) {
    console.log(e)
}
}

export function activate(context: ExtensionContext) {

    workspace.onDidChangeTextDocument(e => addDecorations(window.activeTextEditor))
    window.onDidChangeActiveTextEditor(e => {
        e && addDecorations(e)
    })
    if (window.activeTextEditor) {
        addDecorations(window.activeTextEditor)
    }

}