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/* NSC -- new Scala compiler
* Copyright 2005-2013 LAMP/EPFL
* @author Martin Odersky
*/
package scala.tools.nsc
package backend
package icode
/** This trait ...
*
* @author Iulian Dragos
* @version 1.0
*/
trait TypeStacks {
self: ICodes =>
/* This class simulates the type of the operand
* stack of the ICode.
*/
type Rep = List[TypeKind]
class TypeStack(var types: Rep) {
if (types.nonEmpty)
checkerDebug("Created " + this)
def this() = this(Nil)
def this(that: TypeStack) = this(that.types)
def length: Int = types.length
def isEmpty = length == 0
def nonEmpty = length != 0
/** Push a type on the type stack. UNITs are ignored. */
def push(t: TypeKind) = {
if (t != UNIT)
types = t :: types
}
def head: TypeKind = types.head
/** Removes the value on top of the stack, and returns it. It assumes
* the stack contains at least one element.
*/
def pop: TypeKind = {
val t = types.head
types = types.tail
t
}
/** Return the topmost two values on the stack. It assumes the stack
* is large enough. Topmost element first.
*/
def pop2: (TypeKind, TypeKind) = (pop, pop)
/** Return the topmost three values on the stack. It assumes the stack
* is large enough. Topmost element first.
*/
def pop3: (TypeKind, TypeKind, TypeKind) = (pop, pop, pop)
/** Drop the first n elements of the stack. */
def pop(n: Int): List[TypeKind] = {
val prefix = types.take(n)
types = types.drop(n)
prefix
}
def apply(n: Int): TypeKind = types(n)
/* This method returns a String representation of the stack */
override def toString() =
if (types.isEmpty) "[]"
else types.mkString("[", " ", "]")
override def hashCode() = types.hashCode()
override def equals(other: Any): Boolean = other match {
case x: TypeStack => x.types == types
case _ => false
}
}
}
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