override fun parseVimScriptString()

in vim-engine/src/main/kotlin/com/maddyhome/idea/vim/api/VimStringParserBase.kt [317:488]
166 lines of code
38 McCabe index (conditional complexity)

  override fun parseVimScriptString(string: String): String {
    val result = StringBuilder()
    var state = VimStringState.INIT
    var specialKeyBuilder: StringBuilder? = null
    var digitsLeft = 0
    var number = 0
    val vimStringWithForceEnd = string + 0.toChar()
    var i = 0
    while (i < vimStringWithForceEnd.length) {
      val c = vimStringWithForceEnd[i]
      when (state) {
        VimStringState.INIT -> if (c == '\\') {
          state = VimStringState.ESCAPE
        } else if (c.code == 0) {
          i = vimStringWithForceEnd.length
        } else {
          result.append(c)
        }

        VimStringState.ESCAPE -> {
          val octalToDigital = octalDigitToNumber(c)
          if (octalToDigital != null) {
            number = octalToDigital
            digitsLeft = 2
            state = VimStringState.OCTAL_NUMBER
          } else if (Character.toLowerCase(c) == 'x') {
            digitsLeft = 2
            state = VimStringState.HEX_NUMBER
          } else if (c == 'u') {
            digitsLeft = 4
            state = VimStringState.HEX_NUMBER
          } else if (c == 'U') {
            digitsLeft = 8
            state = VimStringState.HEX_NUMBER
          } else if (c == 'b') {
            result.append(8.toChar())
            state = VimStringState.INIT
          } else if (c == 'e') {
            result.append(27.toChar())
            state = VimStringState.INIT
          } else if (c == 'f') {
            result.append(12.toChar())
            state = VimStringState.INIT
          } else if (c == 'n') {
            result.append('\n')
            state = VimStringState.INIT
          } else if (c == 'r') {
            result.append('\r')
            state = VimStringState.INIT
          } else if (c == 't') {
            result.append('\t')
            state = VimStringState.INIT
          } else if (c == '\\') {
            result.append('\\')
            state = VimStringState.INIT
          } else if (c == '"') {
            result.append('"')
            state = VimStringState.INIT
          } else if (c == '<') {
            state = VimStringState.SPECIAL
            specialKeyBuilder = StringBuilder()
          } else if (c.code == 0) {
            i = vimStringWithForceEnd.length // force end of the string
          } else {
            result.append(c)
            state = VimStringState.INIT
          }
        }

        VimStringState.OCTAL_NUMBER -> {
          val value = octalDigitToNumber(c)
          if (value != null) {
            digitsLeft -= 1
            number = number * 8 + value
            if (digitsLeft == 0 || i == vimStringWithForceEnd.length - 1) {
              if (number != 0) {
                result.append(number.toChar())
              } else {
                i = vimStringWithForceEnd.length
              }
              number = 0
              state = VimStringState.INIT
            }
          } else {
            if (number != 0) {
              result.append(number.toChar())
            } else {
              i = vimStringWithForceEnd.length
            }
            number = 0
            digitsLeft = 0
            state = VimStringState.INIT
            i -= 1
          }
        }

        VimStringState.HEX_NUMBER -> {
          val `val` = hexDigitToNumber(c)
          if (`val` == null) {
            // if there was at least one number after '\', append number, otherwise - append letter after '\'
            if (vimStringWithForceEnd[i - 2] == '\\') {
              result.append(vimStringWithForceEnd[i - 1])
            } else {
              if (number != 0) {
                result.append(number.toChar())
              } else {
                i = vimStringWithForceEnd.length
              }
            }
            number = 0
            digitsLeft = 0
            state = VimStringState.INIT
            i -= 1
          } else {
            number = number * 16 + `val`
            digitsLeft -= 1
            if (digitsLeft == 0 || i == vimStringWithForceEnd.length - 1) {
              if (number != 0) {
                result.append(number.toChar())
              } else {
                i = vimStringWithForceEnd.length
              }
              number = 0
              state = VimStringState.INIT
            }
          }
        }

        VimStringState.SPECIAL -> {
          if (c.code == 0) {
            result.append(specialKeyBuilder)
          }
          if (c == '>') {
            val specialKey = parseSpecialKey(specialKeyBuilder.toString(), 0)
            if (specialKey != null) {
              var keyCode = specialKey.keyCode
              var useKeyCode = true
              if (specialKey.keyCode == 0) {
                keyCode = specialKey.keyChar.code
              } else if (specialKey.modifiers and InputEvent.CTRL_DOWN_MASK == InputEvent.CTRL_DOWN_MASK) {
                if (isControlCharacterKeyCode(specialKey.keyCode)) {
                  keyCode = if (specialKey.keyCode == 'J'.code) {
                    // 'J' is a special case, keycode 10 is \n char
                    0
                  } else {
                    specialKey.keyCode - 'A'.code + 1
                  }
                } else {
                  useKeyCode = false
                  result.append("\\<${specialKeyBuilder}>")
                }
              }
              if (useKeyCode) {
                result.append(keyCode.toChar())
              }
            } else {
              result.append("<").append(specialKeyBuilder).append(">")
            }
            specialKeyBuilder = StringBuilder()
            state = VimStringState.INIT
          } else if (c.code == 0) {
            result.append("<").append(specialKeyBuilder)
            state = VimStringState.INIT
          } else {
            specialKeyBuilder!!.append(c)
          }
        }
      }
      i += 1
    }
    return result.toString()
  }