Method performDecode

src/Encoder/TapCode.js:118–148

* Performs decode on given content. * @protected * @param {Chain} content * @return {number[]|string|Uint8Array|Chain} Decoded content

(content)

   * @return {number[]|string|Uint8Array|Chain} Decoded content
   */
  performDecode (content) {
    const tapMark = this.getSettingValue('tapMark').getCodePoints()
    const tapMarkLength = tapMark.length
    const input = content.getCodePoints()

    let coordinates = ''
    let i = 0
    let j = -1
    let value = 0

    // Iterate through tap marks
    while ((j = ArrayUtil.indexOfSlice(input, tapMark, j + 1)) !== -1) {
      // Check if the current dot is adjacent to the previous one
      if (i === 0 || j === i + tapMarkLength) {
        // Increase current coordinate value
        value++
      } else {
        // Append coordinate
        coordinates += value.toString()
        value = 1
      }

      i = j
    }

    // Append last coordinate
    coordinates += value.toString()

    // Decode coordinates using Polybius square
    return this._polybiusSquare.decode(coordinates)
  }
}