关于模式匹配语句的Scala 2.8.0.RC2编译器问题?

时间:2010-05-24 10:44:14

标签: scala pattern-matching extractor

为什么以下模块无法在Scala 2.8.RC [1,2]上编译?

object Test {

import util.matching.Regex._

val pVoid = """\s*void\s*""".r
val pVoidPtr = """\s*(const\s+)?void\s*\*\s*""".r
val pCharPtr = """\s*(const\s+)GLchar\s*\*\s*""".r
val pIntPtr = """\s*(const\s+)?GLint\s*\*\s*""".r
val pUintPtr = """\s*(const\s+)?GLuint\s*\*\s*""".r
val pFloatPtr = """\s*(const\s+)?GLfloat\s*\*\s*""".r
val pDoublePtr = """\s*(const\s+)?GLdouble\s*\*\s*""".r
val pShortPtr = """\s*(const\s+)?GLshort\s*\*\s*""".r
val pUshortPtr = """\s*(const\s+)?GLushort\s*\*\s*""".r
val pInt64Ptr = """\s*(const\s+)?GLint64\s*\*\s*""".r
val pUint64Ptr = """\s*(const\s+)?GLuint64\s*\*\s*""".r

def mapType(t: String): String = t.trim match {
  case pVoid() => "Unit"
  case pVoidPtr() => "ByteBuffer"
  case pCharPtr() => "CharBuffer"
  case pIntPtr() | pUintPtr() => "IntBuffer"
  case pFloatPtr() => "FloatBuffer"
  case pShortPtr() | pUshortPtr() => "ShortBuffer"
  case pDoublePtr() => "DoubleBuffer"
  case pInt64Ptr() | pUint64Ptr() => "LongBuffer"
  case x => x
}
}

更新1

在按照答案中的建议后,下一个问题是编译持续时间太长。有趣的是,如果我删除上面的2个case语句,我会得到以下编译器错误:

object Test {

    import util.matching.Regex._

    val PVoid = """\s*void\s*""".r
    val PVoidPtr = """\s*(const\s+)?void\s*\*\s*""".r
    val PCharPtr = """\s*(const\s+)GLchar\s*\*\s*""".r
    val PIntPtr = """\s*(const\s+)?GLint\s*\*\s*""".r
    val PUintPtr = """\s*(const\s+)?GLuint\s*\*\s*""".r
    val PFloatPtr = """\s*(const\s+)?GLfloat\s*\*\s*""".r
    val PDoublePtr = """\s*(const\s+)?GLdouble\s*\*\s*""".r
    val PShortPtr = """\s*(const\s+)?GLshort\s*\*\s*""".r
    val PUshortPtr = """\s*(const\s+)?GLushort\s*\*\s*""".r
    val PInt64Ptr = """\s*(const\s+)?GLint64\s*\*\s*""".r
    val PUint64Ptr = """\s*(const\s+)?GLuint64\s*\*\s*""".r

    def mapType(t: String): String = t.trim match {
      case PVoid() => "Unit"
      case PVoidPtr() => "ByteBuffer"
      case PCharPtr() => "CharBuffer"
      case PIntPtr() | PUintPtr() => "IntBuffer"
      case PFloatPtr() => "FloatBuffer"
      case PShortPtr() | PUshortPtr() => "ShortBuffer"
      case PDoublePtr() => "DoubleBuffer"
      case PInt64Ptr() | PUint64Ptr() => "LongBuffer"
      case x => x
    }
}


Exception in thread "main" java.lang.Error:ch.epfl.lamp.fjbg.JCode$OffsetTooBigException: offset too big to fit in 16 bits: 43772
at ch.epfl.lamp.fjbg.JFieldOrMethod.writeTo(JFieldOrMethod.java:114)
at ch.epfl.lamp.fjbg.JClass.writeTo(JClass.java:315)

1 个答案:

答案 0 :(得分:3)

您正在尝试使用util.matching.Regex作为提取器模式。你可以这样做,因为这个类定义了一个unapplySeq方法。在模式匹配中,对提取器模式的引用必须以大写字母开头。

val PVoid = """\s*void\s*""".r

def mapType(t: String): String = t.trim match {
  case PVoid() => "Unit"
  case x => x
}

<强>更新

以下是您的代码的完整,可编译版本:

object Test {

    import util.matching.Regex._

    val PVoid = """\s*void\s*""".r
    val PVoidPtr = """\s*(const\s+)?void\s*\*\s*""".r
    val PCharPtr = """\s*(const\s+)GLchar\s*\*\s*""".r
    val PIntPtr = """\s*(const\s+)?GLint\s*\*\s*""".r
    val PUintPtr = """\s*(const\s+)?GLuint\s*\*\s*""".r
    val PFloatPtr = """\s*(const\s+)?GLfloat\s*\*\s*""".r
    val PDoublePtr = """\s*(const\s+)?GLdouble\s*\*\s*""".r
    val PShortPtr = """\s*(const\s+)?GLshort\s*\*\s*""".r
    val PUshortPtr = """\s*(const\s+)?GLushort\s*\*\s*""".r
    val PInt64Ptr = """\s*(const\s+)?GLint64\s*\*\s*""".r
    val PUint64Ptr = """\s*(const\s+)?GLuint64\s*\*\s*""".r

    def mapType(t: String): String = t.trim match {
      case PVoid() => "Unit"
      case PVoidPtr() => "ByteBuffer"
      case PCharPtr() => "CharBuffer"
      case PIntPtr() | PUintPtr() => "IntBuffer"
      case x => x match {
        case PFloatPtr() => "FloatBuffer"
        case PShortPtr() | PUshortPtr() => "ShortBuffer"
        case PDoublePtr() => "DoubleBuffer"
        case PInt64Ptr() | PUint64Ptr() => "LongBuffer"
        case x => x
      }
    }
}

将模式匹配分解为解决方法错误#1113