patmatnew.scala

JAVA 语言的函数式编程扩展

    case (_, Nil) => 'b'
    case (h1 :: t1, h2 :: t2) => 'c'
  }

  def k (x:AnyRef) = x match {
    case null => 1
    case _ => 2
  }

  val FooBar = 42
  def lala() = 42 match {
    case FooBar => true
  }

  object Bug1270  { // unapply13
  
    class Sync {
      def apply(x: Int): Int = 42
      def unapply(scrut: Any): Option[Int] = None
    }
    
    class Buffer {
      object Get extends Sync
      
      var ps: PartialFunction[Any, Any] = {
        case Get(y) if y > 4 => // y gets a wildcard type for some reason?! hack 
      }
    }
    
    println((new Buffer).ps.isDefinedAt(42))
  }

  object Bug1261 {
    sealed trait Elem
    case class Foo extends Elem
    case class Bar extends Elem
    trait Row extends Elem
    object Row {
      def unapply(r: Row) = true
      
      def f(elem: Elem) {
        elem match {
          case Bar() => ;
          case Row() => ;
          case Foo() => ; // used to give ERROR (unreachable code)
        }}}
  }
/*
  object Feature1196 {
    def f(l: List[Int]) { }
    
    val l: Seq[Int] = List(1, 2, 3)
    
    l match {
      case x @ List(1, _) => f(x) // x needs to get better type List[int] here
    }
  }
*/
  object TestIfOpt { //compile-only "test EqualsPatternClass in combination with MixTypes opt, bug #1278"
     trait Token {
       val offset : Int
       def matching : Option[Token]
     }
    def go(tok : Token) = (tok.matching: @unchecked) match {
      case Some(other) if true => Some(other)
      case _ if true => tok.matching match {
        case Some(other) => Some(other)
        case _ => None
      }
    }
  }

  object Go { // bug #1277 compile-only
    trait Core { def next : Position = null }
    trait Dir
    val NEXT = new Dir{}
    
    trait Position extends Core
    
    (null:Core,null:Dir) match {
      case (_, NEXT) if true => false // no matter whether NEXT test succeed, cannot throw column because of guard
      case (at2:Position,dir) => true
    }
  }

  trait Outer { // bug #1282 compile-only
    object No
    trait File {
      (null:AnyRef) match {
        case No => false
      }
    }
  }

  object cast2 { // #1281

    class Sync {
      def unapplySeq(scrut: Int): Option[Seq[Int]] = {
        println("unapplySeq: "+scrut)
        if (scrut == 42) Some(List(1, 2))
        else None
      }
    }
    
    class Buffer {
      val Get = new Sync
      
      val jp: PartialFunction[Any, Any] = {
        case Get(xs) => println(xs) // the argDummy <unapply-selector> should have proper arg.tpe (Int in this case)
      }
    }
    
    println((new Buffer).jp.isDefinedAt(40))
    println((new Buffer).jp.isDefinedAt(42))
  }

  object ClassDefInGuard extends TestCase("classdef in guard") { // compile-and-load only
    val z:PartialFunction[Any,Any] = {
      case x::xs if xs.forall { y => y.hashCode() > 0 } => 1
    }

    override def runTest {
    val s:PartialFunction[Any,Any] = {
      case List(4::xs)                => 1
      case List(5::xs)                => 1
      case _                if false                               => 
      case List(3::xs) if List(3:Any).forall { g => g.hashCode() > 0 } => 1
    }
      z.isDefinedAt(42)
      s.isDefinedAt(42)
      // just load the thing, to see if the classes are found

      (None:Option[Boolean] @unchecked) match {
        case x if x.map(x => x).isEmpty =>
      }
    }
  }

  // bug#457

  object Bug457 extends TestCase("Bug457") {
    def method1() = {
      val x = "Hello, world"; val y = 100;
      y match {
        case _: Int if (x match { case t => t.trim().length() > 0 }) => false;
        case _ => true;
      }}

    def method2(): scala.Boolean = {
      val x: String = "Hello, world"; val y: scala.Int = 100; {
        var temp1: scala.Int = y;
        var result: scala.Boolean = false;
        if (
          {
            var result1: scala.Boolean = true;
            if (y == 100)
              result1
            else
              throw new MatchError("crazybox.scala, line 11")
          } && (y > 90)
        )
          result
            else
              throw new MatchError("crazybox.scala, line 9")
      }}

    override def runTest {
      method1();
      method2();
    }
  }

  // bug#508

  object Bug508 extends TestCase("aladdin #508") { 
    case class Operator(x: Int);
    val EQ = new Operator(2);
    
    def analyze(x: Pair[Operator, Int]) = x match {
      case Pair(EQ, 0) => "0"
      case Pair(EQ, 1) => "1"
      case Pair(EQ, 2) => "2"
    }
    override def runTest {
      val x = Pair(EQ, 0);
      assertEquals("0", analyze(x)); // should print "0"
      val y = Pair(EQ, 1);
      assertEquals("1", analyze(y)); // should print "1"
      val z = Pair(EQ, 2);
      assertEquals("2", analyze(z)); // should print "2"
    }    
  }

  // bug#789
  
  object Bug789 extends TestCase("aladdin #789") { // don't do this at home

    trait Impl
    
    trait SizeImpl extends Impl { def size = 42 }
    
    trait ColorImpl extends Impl { def color = "red" }
    
    type Both = SizeImpl with ColorImpl
    
    def info(x:Impl) = x match {
      case x:Both      => "size  "+x.size+" color "+x.color // you wish
      case x:SizeImpl  => "!size "+x.size
      case x:ColorImpl => "color "+x.color
      case _           => "n.a."
    }
    
    def info2(x:Impl) = x match {
      case x:SizeImpl with ColorImpl  => "size  "+x.size+" color "+x.color // you wish
      case x:SizeImpl  => "!size "+x.size
      case x:ColorImpl => "color "+x.color
      case _           => "n.a."
    }
    
    override def runTest {
      // make up some class that has a size
      class MyNode extends SizeImpl
      assertEquals("!size 42", info(new MyNode))
      assertEquals("!size 42", info2(new MyNode))
    }
  }

  // bug#995

  object Bug995 extends TestCase("aladdin #995") {
    def foo(v: Any): String = v match {
      case s: Seq[_] => "Seq" // see hack in object Seq.unapplySeq
      //case a: AnyRef if runtime.ScalaRunTime.isArray(a) => "Array"
      case _ => v.toString
    }
    override def runTest { assertEquals("Seq", foo(Array(0))) } 
  }

  // bug#1093 (contribution #460)

  object Bug1093 extends TestCase("aladdin #1093") {
    override def runTest {assertTrue(Some(3) match {
      case Some(1 | 2) => false
      case Some(3) => true
    })}
  }

  // bug#1094 (contribution #461)

  object Bug1094 extends TestCase("aladdin #1094") {
    def foo(ps: String*) = "Foo"
    case class X(p: String, ps: String*)
    def bar =
      X("a", "b") match {
        case X(p, ps @ _*) => foo(ps : _*)
      }
    override def runTest { assertEquals("Foo", bar) }
  }

  // #2

  class Outer_2 {
    case class Foo(x: int, y: int) {
      override def equals(other: Any) = other match {
        case Outer_2.this.Foo(`x`, `y`) => true
        case _ => false
      }
    }
  }
  
  object Ticket2 extends TestCase("#2") { override def runTest {
    val o1 = new Outer_2; val o2 = new Outer_2; val x: Any = o1.Foo(1, 2); val y: Any = o2.Foo(1, 2)
    assertFalse("equals test returns true (but should not)", x equals y)
    assertTrue("match enters wrong case", x match {
      case o2.Foo(x, y) => false; 
      case o1.Foo(x, y) => true
      case _ => false
    })
  }}

// #11

  class MyException1 extends Exception

  // Commenting out the following line and uncommenting the second line
  // will cause the test to succeed.
  trait SpecialException extends MyException1
  // trait SpecialException
  
  class MyException2 extends MyException1 with SpecialException
  
  object Ticket11 extends TestCase("#11") {
    override def runTest {
      Array[Throwable](new Exception("abc"),
                       new MyException1,
                       new MyException2).foreach { e =>
                         try {
                           throw e
                         } catch {
                           case e : SpecialException => {
                             assume(e.isInstanceOf[SpecialException])
                           }
                           case e => {
                             assume(e.isInstanceOf[Throwable])
                           }
                         }
                                                }
    }
  }

  // #37
  
  object Ticket37 extends TestCase("#37") {
    def foo() {}
    val (a,b) = { foo(); (2,3) }
    override def runTest { assertEquals(this.a, 2) }
  }

  // #44

  trait _X {
    case class _Foo();
    object _Bar {
      def unapply(foo: _Foo):Boolean = true;
    }
  }
  object Y extends _X {
    val foo = _Foo()
    foo match {
      case _Bar() => 
      case _      => assert(false)
    }
  }
  object Ticket44 extends TestCase("#44") {
    override def runTest { assert(Y.toString ne null) /*instantiate Y*/ }
  }

  object Ticket211 extends TestCase("#211") {
    override def runTest {
      (Some(123):Option[Int]) match {
        case (x:Option[a]) if false => {};
        case (y:Option[b]) => {};
      }
    }
  }

  sealed abstract class Tree
  case class Node(l: Tree, v: Int, r: Tree) extends Tree
  case object EmptyTree extends Tree
  
  object Ticket335 extends TestCase("#335") { // compile-only
    override def runTest {
      (EmptyTree: Tree @unchecked) match {
        case Node(_,v,_) if (v == 0) => 0
        case EmptyTree => 2
      }
    }
  }

// this test case checks nothing more than whether
//   case N for object N is translated to a check scrutinee.equals(N)
//  (or the other way round)... for a long time, we got away with
//  scrutinee eq N, but those golden days are, apparently, over.
  object Ticket346 extends TestCase("#346") {

class L(val content: List[Int]) {

    def isEmpty = content.isEmpty
    def head = content.head
    def tail = content.tail

    override def equals(that: Any): Boolean = {
        val result = that.isInstanceOf[N.type]
        println("L("+content+").equals("+that+") returning "+result)
        result
    }
}

object N extends L(Nil) {
    
    override def equals(that: Any): Boolean = {
        val result = (that.isInstanceOf[L] && that.asInstanceOf[L].isEmpty)
        //println("N.equals("+that+") returning "+result)
        result
    }
}

object C {

    def unapply(xs: L): Option[(Int, L)] = {
        if (xs.isEmpty)
            { println("xs is empty"); None }
        else
            Some((xs.head, new L(xs.tail)))
    }

}


    def empty(xs : L) : Boolean = xs match {
        case N => true
        case _ => false
    }

    def singleton(xs : L) : Boolean = xs match {
        case C(_, N) => true
        case _ => false
    }

override def runTest() {
    assertTrue(empty( new L(Nil) ))
    assertTrue(singleton( new L(List(1)) ))
}

}  // end Ticket346

  object Ticket495bis { // compile-only
    def signum(x: Int): Int = 
      x match { 
        case 0 => 0
        case _ if x < 0 => -1
        case _ if x > 0 => 1
      }
    def pair_m(x: Int, y: Int) = 
      (x,y) match {
        case (_, 0)  => 0
        case (-1, _) => -1
        case (_, _)  => 1
      }
  }

  object Ticket522 { // compile-only
  class Term[X]
  object App { 
     // i'm hidden
     case class InternalApply[Y,Z](fun:Y=>Z, arg:Y) extends Term[Z]

     def apply[Y,Z](fun:Y=>Z, arg:Y): Term[Z] = 
       new InternalApply[Y,Z](fun,arg)

     def unapply[X](arg: Term[X]): Option[(Y=>Z,Y)] forSome {type Y; type Z} = 
         arg match {
           case i:InternalApply[y,z] => Some(i.fun, i.arg)
           case _                    => None
         }
  }

  App({x: Int => x}, 5) match {
    case App(arg, a) => 
  }
  } // end Ticket522


  object Ticket710 {  // compile-only
    def method: Unit = {
      sealed case class Parent
      case object Child extends Parent
      val x: Parent = Child
      x match {
        case Child => ()
      }
    }
   }
}