rust-analyzer/editors/code/src/highlighting.ts

import * as vscode from 'vscode';
import * as lc from 'vscode-languageclient';

import { Server } from './server';

export interface Decoration {
    range: lc.Range;
    tag: string;
}

export class Highlighter {
    private decorations: { [index: string]: vscode.TextEditorDecorationType };
    constructor() {
        this.decorations = {};
    }

    public removeHighlights() {
        for (const tag in this.decorations) {
            this.decorations[tag].dispose();
        }

        this.decorations = {};
    }

    public setHighlights(
        editor: vscode.TextEditor,
        highlights: Decoration[],
    ) {
        // Initialize decorations if necessary
        //
        // Note: decoration objects need to be kept around so we can dispose them
        // if the user disables syntax highlighting
        if (Object.keys(this.decorations).length === 0) {
            this.initDecorations();
        }

        const byTag: Map<string, vscode.Range[]> = new Map();
        for (const tag in this.decorations) {
            byTag.set(tag, []);
        }

        for (const d of highlights) {
            if (!byTag.get(d.tag)) {
                console.log(`unknown tag ${d.tag}`);
                continue;
            }
            byTag.get(d.tag)!.push(
                Server.client.protocol2CodeConverter.asRange(d.range),
            );
        }

        for (const tag of byTag.keys()) {
            const dec: vscode.TextEditorDecorationType = this.decorations[tag];
            const ranges = byTag.get(tag)!;
            editor.setDecorations(dec, ranges);
        }
    }

    private initDecorations() {
        const decor = (obj: any) => vscode.window.createTextEditorDecorationType({ color: obj });
        this.decorations = {
            background: decor('#3F3F3F'),
            error: vscode.window.createTextEditorDecorationType({
                borderColor: 'red',
                borderStyle: 'none none dashed none',
            }),
            comment: decor('#7F9F7F'),
            string: decor('#CC9393'),
            keyword: decor('#F0DFAF'),
            function: decor('#93E0E3'),
            parameter: decor('#94BFF3'),
            builtin: decor('#DD6718'),
            text: decor('#DCDCCC'),
            attribute: decor('#BFEBBF'),
            literal: decor('#DFAF8F'),
        };
    }
}