cbor-edn/lib/spec.js

Parse CBOR Extended Diagnostic Notation as defined by [draft-ietf-cbor-edn-literals-16](https://www.ietf.org/archive/id/draft-ietf-cbor-edn-literals-16.html) and some CBOR working group discussions.

import { encode, encodedNumber, getEncoded } from 'cbor2';
import { MT } from './constants.js';
import { assert } from './assert.js';
export const ORIGINAL = Symbol('ORIGINAL');
/**
 * Encode a number as a Uint8Array.
 *
 * @param n Int or Float to encode.
 * @param spec '' for indefinite, null for default, '0' for one-byte, etc.
 * @param mt Major type to add to integer.
 * @returns Encoded number.
 * @throws On invlid state.
 */
export function numToBytes(n, spec, mt = MT.POS_INT) {
    let num = null;
    if ('float' in n) {
        // Ignore mt
        switch (spec) {
            case null:
            case undefined:
                return encode(n.float, { avoidInts: true }); // Force preferred float
            case '1':
                num = encodedNumber(n.float, 'f16');
                break;
            case '2':
                num = encodedNumber(n.float, 'f32');
                break;
            case '3':
                num = encodedNumber(n.float, 'f64');
                break;
            default:
                throw new Error(`Invalid float spec: _${spec}`);
        }
    }
    else {
        switch (spec) {
            case null:
            case undefined:
                num = encodedNumber(n.int, 'i', mt);
                break;
            case '':
                if (mt < MT.BYTE_STRING || mt > MT.MAP) {
                    throw new Error(`Invalid indefinite encoding for mt ${mt}`);
                }
                return new Uint8Array([0x1f | (mt << 5)]);
            case 'i':
                num = encodedNumber(n.int, 'i0', mt);
                break;
            case '0':
                num = encodedNumber(n.int, 'i8', mt);
                break;
            case '1':
                num = encodedNumber(n.int, 'i16', mt);
                break;
            case '2':
                num = encodedNumber(n.int, 'i32', mt);
                break;
            case '3':
                num = encodedNumber(n.int, 'i64', mt);
                break;
            default:
                throw new Error(`Invalid integer spec: _${spec} for ${JSON.stringify(n)}`);
        }
    }
    const enc = getEncoded(num);
    assert(enc);
    Object.defineProperty(enc, ORIGINAL, {
        configurable: false,
        enumerable: false,
        writable: false,
        value: n,
    });
    return enc;
}