rust/editors/code/src/highlighting.ts

import seedrandom = require('seedrandom');
import * as vscode from 'vscode';
import * as lc from 'vscode-languageclient';

import { Server } from './server';

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

// Based on this HSL-based color generator: https://gist.github.com/bendc/76c48ce53299e6078a76
function fancify(seed: string, shade: 'light' | 'dark') {
    const random = seedrandom(seed);
    const randomInt = (min: number, max: number) => {
        return Math.floor(random() * (max - min + 1)) + min;
    };

    const h = randomInt(0, 360);
    const s = randomInt(42, 98);
    const l = shade === 'light' ? randomInt(15, 40) : randomInt(40, 90);
    return `hsl(${h},${s}%,${l}%)`;
}

export class Highlighter {
    private static initDecorations(): Map<
        string,
        vscode.TextEditorDecorationType
    > {
        const colorContrib = (
            tag: string
        ): [string, vscode.TextEditorDecorationType] => {
            const color = new vscode.ThemeColor('ralsp.' + tag);
            const decor = vscode.window.createTextEditorDecorationType({
                color
            });
            return [tag, decor];
        };

        const decorations: Iterable<
            [string, vscode.TextEditorDecorationType]
        > = [
            colorContrib('comment'),
            colorContrib('string'),
            colorContrib('keyword'),
            colorContrib('keyword.control'),
            colorContrib('keyword.unsafe'),
            colorContrib('function'),
            colorContrib('parameter'),
            colorContrib('constant'),
            colorContrib('type'),
            colorContrib('builtin'),
            colorContrib('text'),
            colorContrib('attribute'),
            colorContrib('literal'),
            colorContrib('macro'),
            colorContrib('variable'),
            colorContrib('variable.mut'),
            colorContrib('field'),
            colorContrib('module')
        ];

        return new Map<string, vscode.TextEditorDecorationType>(decorations);
    }

    private decorations: Map<
        string,
        vscode.TextEditorDecorationType
    > | null = null;

    public removeHighlights() {
        if (this.decorations == null) {
            return;
        }

        // Decorations are removed when the object is disposed
        for (const decoration of this.decorations.values()) {
            decoration.dispose();
        }

        this.decorations = null;
    }

    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 (this.decorations == null) {
            this.decorations = Highlighter.initDecorations();
        }

        const byTag: Map<string, vscode.Range[]> = new Map();
        const colorfulIdents: Map<string, vscode.Range[]> = new Map();
        const rainbowTime = Server.config.rainbowHighlightingOn;

        for (const tag of this.decorations.keys()) {
            byTag.set(tag, []);
        }

        for (const d of highlights) {
            if (!byTag.get(d.tag)) {
                continue;
            }

            if (rainbowTime && d.bindingHash) {
                if (!colorfulIdents.has(d.bindingHash)) {
                    colorfulIdents.set(d.bindingHash, []);
                }
                colorfulIdents
                    .get(d.bindingHash)!
                    .push(
                        Server.client.protocol2CodeConverter.asRange(d.range)
                    );
            } else {
                byTag
                    .get(d.tag)!
                    .push(
                        Server.client.protocol2CodeConverter.asRange(d.range)
                    );
            }
        }

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

        for (const [hash, ranges] of colorfulIdents.entries()) {
            const dec = vscode.window.createTextEditorDecorationType({
                light: { color: fancify(hash, 'light') },
                dark: { color: fancify(hash, 'dark') }
            });
            editor.setDecorations(dec, ranges);
        }
    }
}