Add quotes.isWhileTyping

Author: nicolasstucki

compiler/src/scala/quoted/runtime/impl/QuotesImpl.scala

@@ -76,6 +76,10 @@ class QuotesImpl private (using val ctx: Context) extends Quotes, QuoteUnpickler
 
   object reflect extends reflectModule:
 
+    object CompilationInfo extends CompilationInfoModule:
+      def isWhileTyping: Boolean = !ctx.isAfterTyper
+    end CompilationInfo
+
     extension (expr: Expr[Any])
       def asTerm: Term =
         val exprImpl = expr.asInstanceOf[ExprImpl]

library/src/scala/quoted/Quotes.scala

@@ -217,6 +217,19 @@ trait Quotes { self: runtime.QuoteUnpickler & runtime.QuoteMatching =>
    */
   trait reflectModule { self: reflect.type =>
 
+    /** Module object of `type CompilationInfo`  */
+    val CompilationInfo: CompilationInfoModule
+
+    /** Methods of the module object `val CompilationInfo` */
+    trait CompilationInfoModule { this: CompilationInfo.type =>
+      /** Are we expanding a `inline` macro while typing the program?
+       *
+       *  This will be true when the macro is used in a transparent inline.
+       */
+      def isWhileTyping: Boolean
+    }
+
+
     /** Returns the `Term` representation this expression */
     extension (expr: Expr[Any])
       def asTerm: Term

tests/run-macros/is-in-typer/Macro_1.scala

@@ -0,0 +1,9 @@
+import scala.quoted._
+
+inline def isWhileTyping: Boolean = ${ whileTypeing }
+
+transparent inline def isWhileTypingTransparent: Boolean = ${ whileTypeing }
+
+private def whileTypeing(using Quotes): Expr[Boolean] =
+  import quotes.reflect._
+  Expr(CompilationInfo.isWhileTyping)

tests/run-macros/is-in-typer/Test_2.scala

@@ -0,0 +1,20 @@
+
+@main def Test =
+  assert(!isWhileTyping)
+  assert(isWhileTypingTransparent)
+  assert(f1 == "afterTyper")
+  assert(f2 == "afterTyper")
+  assert(f3 == "inTyper")
+  assert(f4 == "inTyper")
+
+inline def f1 =
+   inline if isWhileTyping then "inTyper" else "afterTyper"
+
+inline def f2 =
+  inline if isWhileTypingTransparent /*delayed*/ then "inTyper" else "afterTyper"
+
+transparent inline def f3 =
+  inline if isWhileTyping /*forced*/ then "inTyper" else "afterTyper"
+
+transparent inline def f4 =
+  inline if isWhileTypingTransparent then "inTyper" else "afterTyper"