preserves/implementations/javascript/packages/core/src/text.ts

import { Value } from './values';

export function stringify(x: any): string {
    if (typeof x?.asPreservesText === 'function') {
        return x.asPreservesText();
    } else {
        try {
            return JSON.stringify(x);
        } catch (_e) {
            return ('' + x).asPreservesText();
        }
    }
}

export function preserves(pieces: TemplateStringsArray, ...values: Value<any>[]): string {
    const result = [pieces[0]];
    values.forEach((v, i) => {
        result.push(stringify(v));
        result.push(pieces[i + 1]);
    });
    return result.join('');
}


declare global {
    interface Object { asPreservesText(): string; }
}

Object.defineProperty(Object.prototype, 'asPreservesText', {
    enumerable: false,
    writable: true,
    value: function(): string { return '#!' + JSON.stringify(this); }
});

Boolean.prototype.asPreservesText = function (): string {
    return this ? '#t' : '#f';
};

Number.prototype.asPreservesText = function (): string {
    return '' + this;
};

String.prototype.asPreservesText = function (): string {
    return JSON.stringify(this);
};

Symbol.prototype.asPreservesText = function (): string {
    // TODO: escaping
    return this.description ?? '||';
};