Add Expr.matches

Author: nicolasstucki

library/src/scala/quoted/Expr.scala

@@ -19,6 +19,17 @@ package quoted {
      */
     final def getValue[U >: T](given qctx: QuoteContext, valueOf: ValueOfExpr[U]): Option[U] = valueOf(this)
 
+    /** Pattern matches `this` against `that`. Effectively performing a deep equality check.
+     *  It does the equivalent of
+     *  ```
+     *  this match
+     *    case '{...} => true // where the contens of the pattern are the contents of `that`
+     *    case _ => false
+     *  ```
+     */
+    final def matches(that: Expr[Any])(given qctx: QuoteContext): Boolean =
+      !scala.internal.quoted.Expr.unapply[Unit, Unit](this)(given that, false, qctx).isEmpty
+
   }
 
   object Expr {

tests/run-macros/flops-rewrite-2/Macro_1.scala

@@ -68,7 +68,7 @@ private class Rewriter(preTransform: List[Transformation[_]] = Nil, postTransfor
     val e2 = preTransform.foldLeft(e)((ei, transform) => transform(ei))
     val e3 = mapChildren(e2)
     val e4 = postTransform.foldLeft(e3)((ei, transform) => transform(ei))
-    if fixPoint && e4 != e then map(e4)
+    if fixPoint && !e4.matches(e) then map(e4)
     else e4
   }
 

tests/run-macros/flops-rewrite-3/Macro_1.scala

@@ -105,7 +105,7 @@ private class Rewriter private (preTransform: List[Transformation] = Nil, postTr
     val e2 = preTransform.foldLeft(e)((ei, transform) => transform(ei))
     val e3 = mapChildren(e2)
     val e4 = postTransform.foldLeft(e3)((ei, transform) => transform(ei))
-    if fixPoint && e4 != e then map(e4) else e4
+    if fixPoint && !e4.matches(e) then map(e4) else e4
   }
 
 }

tests/run-macros/flops-rewrite/Macro_1.scala

@@ -33,7 +33,7 @@ private class Rewriter(preTransform: Expr[Any] => Expr[Any], postTransform: Expr
     val e2 = checkedTransform(e, preTransform)
     val e3 = mapChildren(e2)
     val e4 = checkedTransform(e3, postTransform)
-    if fixPoint && e4 != e then map(e4)
+    if fixPoint && !e4.matches(e) then map(e4)
     else e4
   }
 

tests/run-staging/expr-matches.scala

@@ -0,0 +1,13 @@
+import scala.quoted._
+import scala.quoted.staging._
+
+
+object Test {
+  given Toolbox = Toolbox.make(getClass.getClassLoader)
+  def main(args: Array[String]): Unit = withQuoteContext {
+    assert('{1} matches '{1})
+    assert('{println("foo")} matches '{println("foo")})
+    assert('{println("foo")} matches '{println(${Expr("foo")})})
+    assert('{println(Some("foo"))} matches '{println(${ val a = '{Some("foo")}; a})})
+  }
+}