Type Alias Transcodes<T>

Maps transcode keys to their respective encoding and decoding functions.

Remarks

The keys of this object must exactly match the keys of the TranscodeMap.

Each encode function must take the mapped type as an argument and return a string. Invalid values should throw an error.

Each decode function must take a string as an argument and return the mapped type.

Encoded strings should be articulated such that they sort alphanumerically in the same order as the mapped type. Numerical values should therefore be encoded at a foxed length.

Example

interface MyTranscodeMap extends TranscodeMap {
  fix6: number;
}

const myTranscodes extends Transcodes<MyTranscodeMap> = {
  fix6: {
    encode: (value) => {
      if (
        !isNumber(value) ||
        value > Number.MAX_SAFE_INTEGER / 1000000 ||
        value < Number.MIN_SAFE_INTEGER / 1000000
      )
        throw new Error('invalid fix6');

      const [prefix, abs] = value < 0 ? ['n', -value] : ['p', value];

      return `${prefix}${abs.toFixed(6).padStart(17, '0')}`;
    },
    decode: (value) => {
      if (!isString(value) || !/^[np][0-9]{10}\.[0-9]{6}$/.test(value))
        throw new Error('invalid encoded fix6');

      return (value.startsWith('n') ? -1 : 1) * Number(value.slice(1));
    },
  },
};

console.log(myTranscodes.fix6.encode(-123.45));              //  n0000000123.450000
console.log(myTranscodes.fix6.encode(123.45));               //  p0000000123.450000
console.log(myTranscodes.fix6.encode(100000000000123.45));   //  throws error
console.log(myTranscodes.fix6.encode('foo'));                //  throws error

console.log(myTranscodes.fix6.decode('n0000000123.450000')); // -123.45 (number)
console.log(myTranscodes.fix6.decode('p0000000123.450000')); //  123 (number)
console.log(myTranscodes.fix6.decode('q0000000123.450000')); //  throws error
console.log(myTranscodes.fix6.decode('foo'));                //  throws error
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