remove Rewrite

This commit is contained in:
Mark Harrah 2010-08-14 09:49:28 -04:00
parent 714d21d865
commit 44c49ab531
2 changed files with 0 additions and 92 deletions

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@ -1,42 +0,0 @@
/* sbt -- Simple Build Tool
* Copyright 2010 Mark Harrah
*/
package sbt
import Types._
trait Rewrite[A[_]]
{
def apply[T](node: A[T], rewrite: Rewrite[A]): A[T]
}
object Rewrite
{
def Id[A[_]]: Rewrite[A] = new Rewrite[A] { def apply[T](node: A[T], rewrite: Rewrite[A]) = node }
implicit def specificF[T](f: T => T): Rewrite[Const[T]#Apply] = new Rewrite[Const[T]#Apply] {
def apply[S](node:T, rewrite: Rewrite[Const[T]#Apply]): T = f(node)
}
implicit def pToRewrite[A[_]](p: Param[A,A] => Unit): Rewrite[A] = toRewrite(Param.pToT(p))
implicit def toRewrite[A[_]](f: A ~> A): Rewrite[A] = new Rewrite[A] {
def apply[T](node: A[T], rewrite:Rewrite[A]) = f(node)
}
def compose[A[_]](a: Rewrite[A], b: Rewrite[A]): Rewrite[A] =
new Rewrite[A] {
def apply[T](node: A[T], rewrite: Rewrite[A]) =
a(b(node, rewrite), rewrite)
}
implicit def rewriteOps[A[_]](outer: Rewrite[A]): RewriteOps[A] =
new RewriteOps[A] {
def (g: A ~> A): Rewrite[A] = compose(outer, g)
def andThen(g: A ~> A): Rewrite[A] = compose(g, outer)
def (g: Rewrite[A]): Rewrite[A] = compose(outer, g)
def andThen(g: Rewrite[A]): Rewrite[A] = compose(g, outer)
}
def apply[A[_], T](value: A[T])(implicit rewrite: Rewrite[A]): A[T] = rewrite(value, rewrite)
}
trait RewriteOps[A[_]]
{
def andThen(g: A ~> A): Rewrite[A]
def (g: A ~> A): Rewrite[A]
def (g: Rewrite[A]): Rewrite[A]
}

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/* sbt -- Simple Build Tool
* Copyright 2010 Mark Harrah
*/
package sbt
import Types._
object RewriteTest
{
// dist and add0 show the awkwardness when not just manipulating superstructure:
// would have to constrain the parameters to Term to be instances of Zero/Eq somehow
val dist: Rewrite[Term] = (p: Param[Term, Term]) => p.ret( p.in match {
case Add(Mult(a,b),Mult(c,d)) if a == c=> Mult(a, Add(b,d))
case x => x
})
val add0: Rewrite[Term] = (p: Param[Term, Term]) => p.ret( p.in match {
case Add(V(0), y) => y
case Add(x, V(0)) => x
case x => x
})
val rewriteBU= new Rewrite[Term] {
def apply[T](node: Term[T], rewrite: Rewrite[Term]) = {
def r[T](node: Term[T]) = rewrite(node, rewrite)
node match {
case Add(x, y) => Add(r(x), r(y))
case Mult(x, y) => Mult(r(x), r(y))
case x => x
}
}
}
val d2 = dist add0 rewriteBU
implicit def toV(t: Int): V[Int] = V(t)
implicit def toVar(s: String): Var[Int] = Var[Int](s)
val t1: Term[Int] = Add(Mult(3,4), Mult(4, 5))
val t2: Term[Int] = Add(Mult(4,4), Mult(4, 5))
val t3: Term[Int] = Add(Mult(Add("x", 0),4), Mult("x", 5))
println( Rewrite(t1)(d2) )
println( Rewrite(t2)(d2) )
println( Rewrite(t3)(d2) )
}
sealed trait Term[T]
final case class Add[T](a: Term[T], b: Term[T]) extends Term[T]
final case class Mult[T](a: Term[T], b: Term[T]) extends Term[T]
final case class V[T](v: T) extends Term[T]
final case class Var[T](name: String) extends Term[T]