path: root/src/compiler/scala/tools/nsc/backend/icode/TypeKinds.scala

/* NSC -- new Scala compiler
 * Copyright 2005-2006 LAMP/EPFL
 * @author  Martin Odersky
 */

// $Id$

package scala.tools.nsc.backend.icode

/* A type case

    case UNIT            =>
    case BOOL            =>
    case BYTE            =>
    case SHORT           =>
    case CHAR            =>
    case INT             =>
    case LONG            =>
    case FLOAT           =>
    case DOUBLE          =>
    case REFERENCE(cls)  =>
    case ARRAY(elem)     =>

*/

import scala.collection.mutable.{Map, HashMap}

trait TypeKinds requires ICodes {
  import global._

  /** This class represents a type kind. Type kinds
   * represent the types that the VM know (or the ICode
   * view of what VMs know).
   */
  abstract class TypeKind {

    /** Returns a string representation of this type kind. */
    override def toString(): String = this match {
      case UNIT    => "UNIT"
      case BOOL    => "BOOL"
      case BYTE    => "BYTE"
      case SHORT   => "SHORT"
      case CHAR    => "CHAR"
      case INT     => "INT"
      case LONG    => "LONG"
      case FLOAT   => "FLOAT"
      case DOUBLE  => "DOUBLE"
      case REFERENCE(cls) => "REFERENCE(" + cls.fullNameString + ")"
      case ARRAY(elem) => "ARRAY[" + elem + "]"
      case _       => abort("Unkown type kind.")
    }

    def toType: Type = this match {
      case UNIT            => definitions.UnitClass.tpe
      case BOOL            => definitions.BooleanClass.tpe
      case BYTE            => definitions.ByteClass.tpe
      case SHORT           => definitions.ShortClass.tpe
      case CHAR            => definitions.CharClass.tpe
      case INT             => definitions.IntClass.tpe
      case LONG            => definitions.LongClass.tpe
      case FLOAT           => definitions.FloatClass.tpe
      case DOUBLE          => definitions.DoubleClass.tpe
      case REFERENCE(cls)  => typeRef(cls.typeConstructor.prefix, cls, Nil)
      case ARRAY(elem)     => typeRef(definitions.ArrayClass.typeConstructor.prefix,
                                      definitions.ArrayClass,
                                      elem.toType :: Nil)
      case _ => abort("Unknown type kind.")
    }

    def isReferenceType: Boolean = false
    def isArrayType: Boolean = false
    def isValueType: Boolean = !isReferenceType && !isArrayType


    def isIntType: Boolean = this match {
      case BYTE | SHORT | INT | LONG | CHAR => true
      case _ => false
    }

    def isRealType: Boolean = this match {
      case FLOAT | DOUBLE => true
      case _ => false
    }

    def isNumericType: Boolean = isIntType | isRealType

    def maxType(other: TypeKind): TypeKind

    /** Simple subtyping check */
    def <:<(other: TypeKind): Boolean = (this == other)

    override def equals(other: Any): Boolean =
      this eq other.asInstanceOf[AnyRef]

    /** Is this type a category 2 type in JVM terms? */
    def isWideType: Boolean = this match {
      case DOUBLE | LONG => true
      case _ => false
    }
  }

  /**
   * The least upper bound of two typekinds. They have to be either
   * REFERENCE or ARRAY kinds.
   *
   * The lub is based on the lub of scala types.
   */
  def lub(a: TypeKind, b: TypeKind): TypeKind = {
    def lub0(t1: Type, t2: Type): Type = {
      val lubTpe = global.lub(t1 :: t2 :: Nil)
      assert(lubTpe.symbol.isClass,
             "Least upper bound of " + t1 + " and " + t2 + " is not a class: " + lubTpe)
      lubTpe
    }

    if ((a.isReferenceType || a.isArrayType) &&
        (b.isReferenceType || b.isArrayType))
      toTypeKind(lub0(a.toType, b.toType))
    else if (a == b) a
    else if (a == REFERENCE(definitions.AllClass)) b
    else if (b == REFERENCE(definitions.AllClass)) a
    else throw new CheckerError("Incompatible types: " + a + " with " + b)
  }

  /** The unit value */
  case object UNIT extends TypeKind {
    def maxType(other: TypeKind): TypeKind = other match {
      case UNIT => UNIT
      case _ => abort("Uncomparbale type kinds: UNIT with " + other)
    }
  }

  /** A boolean value */
  case object BOOL extends TypeKind {
    override def maxType(other: TypeKind): TypeKind = other match {
      case BOOL => BOOL
      case _ => abort("Uncomparbale type kinds: BOOL with " + other)
    }
  }

  /** A 1-byte signed integer */
  case object BYTE extends TypeKind {
    override def maxType(other: TypeKind): TypeKind =
      other match {
        case BYTE | SHORT | CHAR | INT | LONG | FLOAT | DOUBLE => other
        case _ => abort("Uncomparbale type kinds: BYTE with " + other)
      }
  }

  /** A 2-byte signed integer */
  case object SHORT extends TypeKind {
    override def maxType(other: TypeKind): TypeKind =
      other match {
        case BYTE | SHORT | CHAR => SHORT;
        case INT | LONG | FLOAT | DOUBLE => other;
        case _ => abort("Uncomparbale type kinds: SHORT with " + other);
      }
  }

  /** A 2-byte signed integer */
  case object CHAR extends TypeKind {
    override def maxType(other: TypeKind): TypeKind =
      other match {
        case BYTE | SHORT | CHAR => CHAR
        case INT | LONG | FLOAT | DOUBLE => other
        case _ => abort("Uncomparbale type kinds: CHAR with " + other)
      }
  }


  /** A 4-byte signed integer */
  case object INT extends TypeKind {
    override def maxType(other: TypeKind): TypeKind =
      other match {
        case BYTE | SHORT | CHAR | INT => INT
        case LONG | FLOAT | DOUBLE => other
        case _ => abort("Uncomparbale type kinds: INT with " + other)
      }
  }

  /** An 8-byte signed integer */
  case object LONG extends TypeKind {
    override def maxType(other: TypeKind): TypeKind =
      other match {
        case BYTE | SHORT | CHAR | INT | LONG => LONG
        case FLOAT | DOUBLE => DOUBLE
        case _ => abort("Uncomparbale type kinds: LONG with " + other)
      }
  }

  /** A 4-byte floating point number */
  case object FLOAT extends TypeKind {
    override def maxType(other: TypeKind): TypeKind = other match {
      case BYTE | SHORT | CHAR | INT | LONG | FLOAT => FLOAT
      case DOUBLE => DOUBLE
      case _ => abort("Uncomparbale type kinds: FLOAT with " + other)
    }
  }

  /** An 8-byte floating point number */
  case object DOUBLE extends TypeKind {
    override def maxType(other: TypeKind): TypeKind =
      if (other.isNumericType)
        DOUBLE
      else
        abort("Uncomparbale type kinds: DOUBLE with " + other)
  }

  /** A string reference */
  // case object STRING extends TypeKind {
  //   override def maxType(other: TypeKind): TypeKind = other match {
  //     case STRING => STRING;
  //     case _   =>
  //       abort("Uncomparbale type kinds: STRING with " + other);
  //   }
  // }

  /** A class type. */
  case class REFERENCE(cls: Symbol) extends TypeKind {
    assert(cls ne null,
           "REFERENCE to null class symbol.")
    assert(cls != definitions.ArrayClass,
           "REFERENCE to Array is not allowed, should be ARRAY[..] instead")
    assert(cls != NoSymbol,
           "REFERENCE to NoSymbol not allowed!")

    override def toString(): String =
      "REFERENCE(" + cls.fullNameString + ")"

    /**
     * Approximate `lub'. The common type of two references is
     * always AnyRef. For 'real' least upper bound wrt to subclassing
     * use method 'lub'.
     */
    override def maxType(other: TypeKind): TypeKind =
      other match {
        case REFERENCE(_) =>
          REFERENCE(definitions.AnyRefClass)
        case _ =>
          abort("Uncomparbale type kinds: REFERENCE with " + other)
      }

    /** Checks subtyping relationship. */
    override def <:<(other: TypeKind): Boolean =
      if (cls == definitions.AllClass)
        true
      else other match {
        case REFERENCE(cls2) =>
          cls.tpe <:< cls2.tpe
        case ARRAY(_) =>
          cls == definitions.AllRefClass
        case _ => false
      }

    override def isReferenceType: Boolean = true;

    override def equals(other: Any): Boolean = other match {
      case REFERENCE(cls2) => cls == cls2
      case _               => false
    }
  }


  case class ARRAY(val elem: TypeKind) extends TypeKind {
    override def toString(): String =
      "ARRAY[" + elem + "]"

    override def isArrayType = true

    /**
     * Approximate `lub'. The common type of two references is
     * always AnyRef. For 'real' least upper bound wrt to subclassing
     * use method 'lub'.
     */
    override def maxType(other: TypeKind): TypeKind =
      other match {
        case REFERENCE(_) =>
          REFERENCE(definitions.AnyRefClass)
        case ARRAY(elem2) =>
          ARRAY(elem maxType elem2)
        case _ =>
          abort("Uncomparbale type kinds: ARRAY with " + other)
      }

    /** Checks subtyping relationship. */
    override def <:<(other: TypeKind): Boolean =
      other match {
        case ARRAY(elem2) =>
          elem <:< elem2
        case REFERENCE(sym) =>
          (sym == definitions.AnyRefClass ||
           sym == definitions.ObjectClass) // TODO: platform dependent!

        case _ => false
      }

    override def equals(other: Any): Boolean = other match {
      case ARRAY(elem2) => elem == elem2
      case _               => false
    }

  }

  /** A boxed value. */
  case class BOXED(kind: TypeKind) extends TypeKind {
    override def toString(): String =
      "BOXED(" + kind + ")"

    /**
     * Approximate `lub'. The common type of two references is
     * always AnyRef. For 'real' least upper bound wrt to subclassing
     * use method 'lub'.
     */
    override def maxType(other: TypeKind): TypeKind =
      other match {
        case REFERENCE(_) | ARRAY(_) | BOXED(_) =>
          REFERENCE(definitions.AnyRefClass)
        case _ =>
          abort("Uncomparbale type kinds: ARRAY with " + other)
      }

    /** Checks subtyping relationship. */
    override def <:<(other: TypeKind): Boolean =
      other match {
        case REFERENCE(sym) =>
          (sym == definitions.AnyRefClass ||
           sym == definitions.ObjectClass) // TODO: platform dependent!

        case BOXED(other) =>
          kind == other

        case _ => false
      }

    override def equals(other: Any): Boolean = other match {
      case BOXED(kind2) => kind == kind2
      case _            => false
    }

  }

 /**
  * Dummy TypeKind to represent the ConcatClass in a platform-independent
  * way. For JVM it would have been a REFERENCE to 'StringBuffer'.
  */
  case object ConcatClass extends TypeKind {
    override def toString() = "ConcatClass"

    /**
     * Approximate `lub'. The common type of two references is
     * always AnyRef. For 'real' least upper bound wrt to subclassing
     * use method 'lub'.
     */
    override def maxType(other: TypeKind): TypeKind =
      other match {
        case REFERENCE(_) =>
          REFERENCE(definitions.AnyRefClass)
        case _ =>
          abort("Uncomparbale type kinds: ConcatClass with " + other)
      }

    /** Checks subtyping relationship. */
    override def <:<(other: TypeKind): Boolean = (this eq other)

    override def isReferenceType: Boolean = false
  }

  ////////////////// Conversions //////////////////////////////


  /** Return the TypeKind of the given type */
  def toTypeKind(t: Type): TypeKind = t match {
    case ThisType(sym) => REFERENCE(sym)

    case SingleType(pre, sym) =>
      primitiveTypeMap get sym match {
        case Some(k) => k
        case None    => REFERENCE(sym)
      }

    case ConstantType(value) =>
      toTypeKind(value.tpe)

    case TypeRef(_, sym, args) =>
      primitiveTypeMap get sym match {
        case Some(k) => k
        case None    =>
          if (sym == definitions.ArrayClass)
            ARRAY(toTypeKind(args.head))
          else
            REFERENCE(sym)
      }

    case ClassInfoType(_, _, sym) =>
      primitiveTypeMap get sym match {
        case Some(k) => k
        case None    =>
          if (sym == definitions.ArrayClass)
            abort("ClassInfoType to ArrayClass!")
          else
            REFERENCE(sym)
      }

    case AttributedType(attribs, tp) =>
      toTypeKind(tp)

    case _ =>
      abort("Unknown type: " + t)
  }

  /** A map from scala primitive Types to ICode TypeKinds */
  private var primitiveTypeMap: Map[Symbol, TypeKind] = null

  /** Initialize the map from scala primitive types to ICode types */
  def initPrimitiveTypeMap = {
    log("Initializing primitive map")
    primitiveTypeMap = new HashMap()
    primitiveTypeMap += definitions.UnitClass -> UNIT
    primitiveTypeMap += definitions.BooleanClass -> BOOL
    primitiveTypeMap += definitions.ByteClass -> BYTE
    primitiveTypeMap += definitions.ShortClass -> SHORT
    primitiveTypeMap += definitions.CharClass -> CHAR
    primitiveTypeMap += definitions.IntClass -> INT
    primitiveTypeMap += definitions.LongClass -> LONG
    if (!forCLDC) {
      primitiveTypeMap += definitions.FloatClass -> FLOAT
      primitiveTypeMap += definitions.DoubleClass -> DOUBLE
    }
//    primitiveTypeMap += definitions.StringClass -> STRING
  }

}