Method performDecode

src/Encoder/BaconCipher.js:151–188

* 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 { alphabet, codes, codeLength } = this._getVariant()
    const aCodePoint = this.getSettingValue('aMark').getCodePointAt(0)
    const bCodePoint = this.getSettingValue('bMark').getCodePointAt(0)

    // Translate content into known marks
    const inputCodePoints = content.getCodePoints()
    let inputMarks = ''
    let i

    for (i = 0; i < inputCodePoints.length; i++) {
      switch (inputCodePoints[i]) {
        case aCodePoint:
          inputMarks += 'a'
          break
        case bCodePoint:
          inputMarks += 'b'
          break
        default:
          // Ignore unknown mark
      }
    }

    // Group marks into code blocks
    const inputCodes = StringUtil.chunk(inputMarks, codeLength)

    // Map each code block to a letter using the alphabet
    let result = ''
    let codeIndex
    for (i = 0; i < inputCodes.length; i++) {
      codeIndex = codes.indexOf(inputCodes[i])
      if (codeIndex !== -1) {
        result += alphabet[codeIndex]
      }
    }

    return result
  }

  /**
   * Composes a spec for the currently selected variant.