Merge pull request #8479 from dotty-staging/refactor-quoted-matching

Refactor scala.quoted.matching

Author: nicolasstucki

docs/docs/reference/metaprogramming/macros.md

@@ -565,13 +565,13 @@ sum
 ### Find implicits within a macro
 
 Similarly to the `summonFrom` construct, it is possible to make implicit search available
-in a quote context. For this we simply provide `scala.quoted.matching.summonExpr`:
+in a quote context. For this we simply provide `scala.quoted.Expr.summon`:
 
 ```scala
 inline def setFor[T]: Set[T] = ${ setForExpr[T] }
 
 def setForExpr[T: Type](using QuoteContext): Expr[Set[T]] = {
-  summonExpr[Ordering[T]] match {
+  Expr.summon[Ordering[T]] match {
     case Some(ord) => '{ new TreeSet[T]()($ord) }
     case _ => '{ new HashSet[T] }
   }
@@ -614,23 +614,19 @@ In case all files are suspended due to cyclic dependencies the compilation will
 
 It is possible to deconstruct or extract values out of `Expr` using pattern matching.
 
-#### scala.quoted.matching
+`scala.quoted` contains objects that can help extracting values from `Expr`.
 
-`scala.quoted.matching` contains objects that can help extracting values from `Expr`.
-
-* `scala.quoted.matching.Const`: matches an expression of a literal value and returns the value.
-* `scala.quoted.matching.Value`: matches an expression of a value and returns the value.
-* `scala.quoted.matching.ExprSeq`: matches an explicit sequence of expresions and returns them. These sequences are useful to get individual `Expr[T]` out of a varargs expression of type `Expr[Seq[T]]`.
-* `scala.quoted.matching.ConstSeq`:  matches an explicit sequence of literal values and returns them.
-* `scala.quoted.matching.ValueSeq`:  matches an explicit sequence of values and returns them.
+* `scala.quoted.Const`/`scala.quoted.Consts`: matches an expression of a literal value (or list of values) and returns the value (or list of values).
+* `scala.quoted.Value`/`scala.quoted.Values`: matches an expression of a value (or list of values) and returns the value (or list of values).
+* `scala.quoted.Varargs`: matches an explicit sequence of expresions and returns them. These sequences are useful to get individual `Expr[T]` out of a varargs expression of type `Expr[Seq[T]]`.
 
 These could be used in the following way to optimize any call to `sum` that has statically known values.
 ```scala
 inline def sum(inline args: Int*): Int = ${ sumExpr('args) }
 private def sumExpr(argsExpr: Expr[Seq[Int]])(using QuoteContext): Expr[Int] = argsExpr match {
-  case ConstSeq(args) => // args is of type Seq[Int]
+  case Varargs(Consts(args)) => // args is of type Seq[Int]
     Expr(args.sum) // precompute result of sum
-  case ExprSeq(argExprs) => // argExprs is of type Seq[Expr[Int]]
+  case Varargs(argExprs) => // argExprs is of type Seq[Expr[Int]]
     val staticSum: Int = argExprs.map {
       case Const(arg) => arg
       case _ => 0
@@ -666,12 +662,12 @@ private def optimizeExpr(body: Expr[Int])(using QuoteContext): Expr[Int] = body
   // Match a call to sum with an argument $n of type Int. n will be the Expr[Int] representing the argument.
   case '{ sum($n) } => n
   // Match a call to sum and extracts all its args in an `Expr[Seq[Int]]`
-  case '{ sum(${ExprSeq(args)}: _*) } => sumExpr(args)
+  case '{ sum(${Varargs(args)}: _*) } => sumExpr(args)
   case body => body
 }
 private def sumExpr(args1: Seq[Expr[Int]])(using QuoteContext): Expr[Int] = {
     def flatSumArgs(arg: Expr[Int]): Seq[Expr[Int]] = arg match {
-      case '{ sum(${ExprSeq(subArgs)}: _*) } => subArgs.flatMap(flatSumArgs)
+      case '{ sum(${Varargs(subArgs)}: _*) } => subArgs.flatMap(flatSumArgs)
       case arg => Seq(arg)
     }
     val args2 = args1.flatMap(flatSumArgs)
@@ -709,7 +705,7 @@ inline def (sc: StringContext).showMe(inline args: Any*): String = ${ showMeExpr
 
 private def showMeExpr(sc: Expr[StringContext], argsExpr: Expr[Seq[Any]])(using qctx: QuoteContext): Expr[String] = {
   argsExpr match {
-    case ExprSeq(argExprs) =>
+    case Varargs(argExprs) =>
       val argShowedExprs = argExprs.map {
         case '{ $arg: $tp } =>
           val showTp = '[Show[$tp]]
@@ -718,7 +714,7 @@ private def showMeExpr(sc: Expr[StringContext], argsExpr: Expr[Seq[Any]])(using
             case None => qctx.error(s"could not find implicit for ${showTp.show}", arg); '{???}
           }
       }
-      val newArgsExpr = Expr.ofSeq(argShowedExprs)
+      val newArgsExpr = Varargs(argShowedExprs)
       '{ $sc.s($newArgsExpr: _*) }
     case _ =>
       // `new StringContext(...).showMeExpr(args: _*)` not an explicit `showMeExpr"..."`

library/src-bootstrapped/dotty/internal/StringContextMacro.scala

@@ -3,8 +3,6 @@
 package dotty.internal
 
 import scala.quoted._
-import scala.quoted.matching._
-import reflect._
 
 object StringContextMacro {
 
@@ -65,9 +63,12 @@ object StringContextMacro {
 
     def notStatic =
       qctx.throwError("Expected statically known String Context", strCtxExpr)
-    def splitParts(seq: Expr[Seq[String]]) = (seq, seq) match {
-      case (ExprSeq(p1), ConstSeq(p2)) => (p1.toList, p2.toList)
-      case (_, _) => notStatic
+    def splitParts(seq: Expr[Seq[String]]) = seq match {
+      case Varargs(p1) =>
+        p1 match
+          case Consts(p2) => (p1.toList, p2.toList)
+          case _ => notStatic
+      case _ => notStatic
     }
     val (partsExpr, parts) = strCtxExpr match {
       case '{ StringContext($parts: _*) } => splitParts(parts)
@@ -76,7 +77,7 @@ object StringContextMacro {
     }
 
     val args = argsExpr match {
-      case ExprSeq(args) => args
+      case Varargs(args) => args
       case _ => qctx.throwError("Expected statically known argument list", argsExpr)
     }
 

library/src-non-bootstrapped/dotty/internal/StringContextMacro.scala

@@ -3,8 +3,6 @@
 package dotty.internal
 
 import scala.quoted._
-import scala.quoted.matching._
-import reflect._
 
 object StringContextMacro {
 

library/src/scala/quoted/matching/Const.scala renamed to library/src/scala/quoted/Const.scala

@@ -1,19 +1,19 @@
 package scala.quoted
-package matching
 
-/** Matches expressions containing literal constant values and extracts the value.
- *  It may match expressions of type Boolean, Byte, Short, Int, Long,
- *  Float, Double, Char, String, ClassTag, scala.Symbol, Null and Unit.
- *
- *  Usage:
- *  ```
- *  (x: Expr[B]) match {
- *    case Const(value: B) => ...
- *  }
- *  ```
- */
+/** Literal constant values */
 object Const {
 
+  /** Matches expressions containing literal constant values and extracts the value.
+   *  It may match expressions of type Boolean, Byte, Short, Int, Long,
+   *  Float, Double, Char, String, ClassTag, scala.Symbol, Null and Unit.
+   *
+   *  Usage:
+   *  ```
+   *  (x: Expr[B]) match {
+   *    case Const(value: B) => ...
+   *  }
+   *  ```
+   */
   def unapply[T](expr: Expr[T])(using qctx: QuoteContext): Option[T] = {
     import qctx.tasty.{_, given _}
     def rec(tree: Term): Option[T] = tree match {

library/src/scala/quoted/Consts.scala

@@ -0,0 +1,26 @@
+package scala.quoted
+
+/** Literal constant values */
+object Consts {
+
+  /** Matches literal sequence of literal constant value expressions and return a sequence of values.
+   *
+   *  Usage:
+   *  ```scala
+   *  inline def sum(args: Int*): Int = ${ sumExpr('args) }
+   *  def sumExpr(argsExpr: Expr[Seq[Int]])(usingusing QuoteContext): Expr[Int] = argsExpr match
+   *    case Varargs(Consts(args)) =>
+   *      // args: Seq[Int]
+   *      ...
+   *  }
+   *  ```
+   */
+  def unapply[T](exprs: Seq[Expr[T]])(using qctx: QuoteContext): Option[Seq[T]] =
+    exprs.foldRight(Option(List.empty[T])) { (elem, acc) =>
+      (elem, acc) match {
+        case (Const(value), Some(lst)) => Some(value :: lst)
+        case (_, _) => None
+      }
+    }
+
+}

library/src/scala/quoted/Expr.scala

@@ -100,25 +100,17 @@ object Expr {
   }
 
   /** Lift a value into an expression containing the construction of that value */
-  def apply[T: Liftable](x: T)(using qctx: QuoteContext): Expr[T] = summon[Liftable[T]].toExpr(x)
+  def apply[T](x: T)(using qctx: QuoteContext, lift: Liftable[T]): Expr[T] = lift.toExpr(x)
 
   /** Lifts this sequence of expressions into an expression of a sequence
    *
    *  Transforms a sequence of expression
    *    `Seq(e1, e2, ...)` where `ei: Expr[T]`
    *  to an expression equivalent to
    *    `'{ Seq($e1, $e2, ...) }` typed as an `Expr[Seq[T]]`
-   *
-   *  Usage:
-   *  ```scala
-   *  '{ List(${Expr.ofSeq(List(1, 2, 3))}: _*) } // equvalent to '{ List(1, 2, 3) }
    *  ```
    */
-  def ofSeq[T](xs: Seq[Expr[T]])(using tp: Type[T], qctx: QuoteContext): Expr[Seq[T]] = {
-    import qctx.tasty.{_, given _}
-    Repeated(xs.map[Term](_.unseal).toList, tp.unseal).seal.asInstanceOf[Expr[Seq[T]]]
-  }
-
+  def ofSeq[T](xs: Seq[Expr[T]])(using tp: Type[T], qctx: QuoteContext): Expr[Seq[T]] = Varargs(xs)
 
   /** Lifts this list of expressions into an expression of a list
    *
@@ -128,7 +120,7 @@ object Expr {
    *    `'{ List($e1, $e2, ...) }` typed as an `Expr[List[T]]`
    */
   def  ofList[T](xs: Seq[Expr[T]])(using Type[T], QuoteContext): Expr[List[T]] =
-    if (xs.isEmpty) '{ Nil } else '{ List(${ofSeq(xs)}: _*) }
+    if (xs.isEmpty) '{ Nil } else '{ List(${Varargs(xs)}: _*) }
 
   /** Lifts this sequence of expressions into an expression of a tuple
    *
@@ -186,7 +178,7 @@ object Expr {
       case Seq('{ $x1: $t1 }, '{ $x2: $t2 }, '{ $x3: $t3 }, '{ $x4: $t4 }, '{ $x5: $t5 }, '{ $x6: $t6 }, '{ $x7: $t7 }, '{ $x8: $t8 }, '{ $x9: $t9 }, '{ $x10: $t10 }, '{ $x11: $t11 }, '{ $x12: $t12 }, '{ $x13: $t13 }, '{ $x14: $t14 }, '{ $x15: $t15 }, '{ $x16: $t16 }, '{ $x17: $t17 }, '{ $x18: $t18 }, '{ $x19: $t19 }, '{ $x20: $t20 }, '{ $x21: $t21 }, '{ $x22: $t22 }) =>
         '{ Tuple22($x1, $x2, $x3, $x4, $x5, $x6, $x7, $x8, $x9, $x10, $x11, $x12, $x13, $x14, $x15, $x16, $x17, $x18, $x19, $x20, $x21, $x22) }
       case _ =>
-        '{ Tuple.fromIArray(IArray(${ofSeq(seq)}: _*)) }
+        '{ Tuple.fromIArray(IArray(${Varargs(seq)}: _*)) }
     }
   }
 
@@ -197,4 +189,20 @@ object Expr {
     ofTuple(elems).cast[Tuple.InverseMap[T, Expr]]
   }
 
+  /** Find an implicit of type `T` in the current scope given by `qctx`.
+   *  Return `Some` containing the expression of the implicit or
+   * `None` if implicit resolution failed.
+   *
+   *  @tparam T type of the implicit parameter
+   *  @param tpe quoted type of the implicit parameter
+   *  @param qctx current context
+   */
+  def summon[T](using tpe: Type[T])(using qctx: QuoteContext): Option[Expr[T]] = {
+    import qctx.tasty.{_, given _}
+    searchImplicit(tpe.unseal.tpe) match {
+      case iss: ImplicitSearchSuccess => Some(iss.tree.seal.asInstanceOf[Expr[T]])
+      case isf: ImplicitSearchFailure => None
+    }
+  }
+
 }

library/src/scala/quoted/matching/Lambda.scala renamed to library/src/scala/quoted/Lambda.scala

@@ -1,5 +1,4 @@
 package scala.quoted
-package matching
 
 /** Lambda expression extractor */
 object Lambda {

library/src/scala/quoted/matching/Value.scala renamed to library/src/scala/quoted/Value.scala

@@ -1,5 +1,4 @@
 package scala.quoted
-package matching
 
 /** Value expressions */
 object Value {

library/src/scala/quoted/ValueOfExpr.scala

@@ -1,7 +1,5 @@
 package scala.quoted
 
-import scala.quoted.matching._
-
 /** A typeclass for types that can be turned from a `quoted.Expr[T]` to a `T` */
 trait ValueOfExpr[T] {
 
@@ -29,7 +27,7 @@ object ValueOfExpr {
 
   private class PrimitiveValueOfExpr[T <: Unit | Null | Int | Boolean | Byte | Short | Int | Long | Float | Double | Char | String] extends ValueOfExpr[T] {
     /** Lift a quoted primitive value `'{ n }` into `n` */
-    def apply(x: Expr[T])(using qctx: QuoteContext): Option[T] = matching.Const.unapply(x)
+    def apply(x: Expr[T])(using qctx: QuoteContext): Option[T] = Const.unapply(x)
   }
 
   given Option_delegate[T](using Type[T], ValueOfExpr[T]) as ValueOfExpr[Option[T]] = new {
@@ -44,8 +42,8 @@ object ValueOfExpr {
 
   given StringContext_delegate as ValueOfExpr[StringContext] = new {
     def apply(x: Expr[StringContext])(using qctx: QuoteContext): Option[StringContext] = x match {
-      case '{ new StringContext(${ConstSeq(args)}: _*) } => Some(StringContext(args: _*))
-      case '{     StringContext(${ConstSeq(args)}: _*) } => Some(StringContext(args: _*))
+      case '{ new StringContext(${Varargs(Consts(args))}: _*) } => Some(StringContext(args: _*))
+      case '{     StringContext(${Varargs(Consts(args))}: _*) } => Some(StringContext(args: _*))
       case _ => None
     }
     override def toString(): String = "scala.quoted.ValueOfExpr.Tuple1_delegate"
@@ -272,9 +270,9 @@ object ValueOfExpr {
 
   given Seq_delegate[T](using Type[T], ValueOfExpr[T]) as ValueOfExpr[Seq[T]] = new {
     def apply(x: Expr[Seq[T]])(using qctx: QuoteContext): Option[Seq[T]] = x match {
-      case ValueSeq(elems) => Some(elems)
-      case '{ scala.collection.Seq[T](${ValueSeq(elems)}: _*) } => Some(elems)
-      case '{ scala.collection.immutable.Seq[T](${ValueSeq(elems)}: _*) } => Some(elems)
+      case Varargs(Values(elems)) => Some(elems)
+      case '{ scala.collection.Seq[T](${Varargs(Values(elems))}: _*) } => Some(elems)
+      case '{ scala.collection.immutable.Seq[T](${Varargs(Values(elems))}: _*) } => Some(elems)
       case _ => None
     }
     override def toString(): String = "scala.quoted.ValueOfExpr.Seq_delegate"

library/src/scala/quoted/Values.scala

@@ -0,0 +1,25 @@
+package scala.quoted
+
+/** Value expressions */
+object Values {
+
+  /** Matches literal sequence of literal constant value expressions and return a sequence of values.
+   *
+   *  Usage:
+   *  ```scala
+   *  inline def sum(args: Int*): Int = ${ sumExpr('args) }
+   *  def sumExpr(argsExpr: Expr[Seq[Int]])(using QuoteContext): Expr[Int] = argsExpr match
+   *    case Varargs(Values(args)) =>
+   *      // args: Seq[Int]
+   *      ...
+   *  }
+   *  ```
+   */
+  def unapply[T](exprs: Seq[Expr[T]])(using valueOf: ValueOfExpr[T], qctx: QuoteContext): Option[Seq[T]] =
+    exprs.foldRight(Option(List.empty[T])) { (elem, acc) =>
+      (elem, acc) match {
+        case (Value(value), Some(lst)) => Some(value :: lst)
+        case (_, _) => None
+      }
+    }
+}

library/src/scala/quoted/matching/ExprSeq.scala renamed to library/src/scala/quoted/Varargs.scala

@@ -1,17 +1,33 @@
 package scala.quoted
-package matching
 
 /** Literal sequence of expressions */
-object ExprSeq {
+object Varargs {
+
+  /** Lifts this sequence of expressions into an expression of a sequence
+   *
+   *  Transforms a sequence of expression
+   *    `Seq(e1, e2, ...)` where `ei: Expr[T]`
+   *  to an expression equivalent to
+   *    `'{ Seq($e1, $e2, ...) }` typed as an `Expr[Seq[T]]`
+   *
+   *  Usage:
+   *  ```scala
+   *  '{ List(${Varargs(List(1, 2, 3))}: _*) } // equvalent to '{ List(1, 2, 3) }
+   *  ```
+   */
+  def apply[T](xs: Seq[Expr[T]])(using tp: Type[T], qctx: QuoteContext): Expr[Seq[T]] = {
+    import qctx.tasty.{_, given _}
+    Repeated(xs.map[Term](_.unseal).toList, tp.unseal).seal.asInstanceOf[Expr[Seq[T]]]
+  }
 
   /** Matches a literal sequence of expressions and return a sequence of expressions.
    *
    *  Usage:
    *  ```scala
    *  inline def sum(args: Int*): Int = ${ sumExpr('args) }
    *  def sumExpr(argsExpr: Expr[Seq[Int]])(using QuoteContext): Expr[Int] = argsExpr match
-   *    case ExprSeq(argExprs) =>
-   *      // argExprs: Seq[Expr[Int]]
+   *    case Varargs(argVarargs) =>
+   *      // argVarargs: Seq[Expr[Int]]
    *      ...
    *  }
    *  ```

library/src/scala/quoted/matching/ConstSeq.scala

@@ -16,15 +16,11 @@ object ConstSeq {
    *  }
    *  ```
    */
-  def unapply[T](expr: Expr[Seq[T]])(using qctx: QuoteContext): Option[Seq[T]] = expr match {
-    case ExprSeq(elems) =>
-      elems.foldRight(Option(List.empty[T])) { (elem, acc) =>
-        (elem, acc) match {
-          case (Const(value), Some(lst)) => Some(value :: lst)
-          case (_, _) => None
-        }
-      }
-    case _ => None
-  }
+  @deprecated("use scala.quoted.Varargs(scala.quoted.Const(_)) instead", "0.23.0")
+  def unapply[T](expr: Expr[Seq[T]])(using qctx: QuoteContext): Option[Seq[T]] =
+    import scala.quoted.Const
+    expr match
+      case Varargs(Consts(elems)) => Some(elems)
+      case _ => None
 
 }