flatMap now inherits the overflows property from the root parser

j-mie6 · Jul 10, 2023 · 66974b6 · 66974b6
1 parent 4cdbaeb
commit 66974b6
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Showing 3 changed files with 10 additions and 5 deletions.
diff --git a/parsley/shared/src/main/scala/parsley/internal/deepembedding/Cont.scala b/parsley/shared/src/main/scala/parsley/internal/deepembedding/Cont.scala
@@ -24,6 +24,7 @@ private [deepembedding] abstract class ContOps[Cont[_, +_]] {
     def map[R, A, B](c: Cont[R, A], f: A => B): Cont[R, B]
     def flatMap[R, A, B](c: Cont[R, A], f: A => Cont[R, B]): Cont[R, B]
     def suspend[R, A](x: =>Cont[R, A]): Cont[R, A]
+    def isStackSafe: Boolean
     // $COVERAGE-OFF$
     // This needs to be lazy, because I'm an idiot when I use it
     def `then`[R, A, B](c: Cont[R, A], k: =>Cont[R, B]): Cont[R, B] = flatMap[R, A, B](c, _ => k)
@@ -52,6 +53,7 @@ private [deepembedding] object Cont {
         override def flatMap[R, A, B](mx: Impl[R, A], f: A => Impl[R, B]): Impl[R, B] = k => new Thunk(() => mx(x => f(x)(k)))
         override def suspend[R, A](x: =>Impl[R, A]): Impl[R, A] = k => new Thunk(() => x(k))
         override def `then`[R, A, B](mx: Impl[R, A], my: =>Impl[R, B]): Impl[R, B] = k => new Thunk(() => mx(_ => my(k)))
+        override def isStackSafe: Boolean = true
     }
 }
 
@@ -64,5 +66,6 @@ private [deepembedding] object Id {
         override def flatMap[R, A, B](c: Impl[R, A], f: A => Impl[R, B]): Impl[R, B] = f(c)
         override def suspend[R, A](x: =>Impl[R, A]): Impl[R, A] = x
         override def as[R, A, B](c: Impl[R, A], x: =>B): Impl[R, B] = x
+        override def isStackSafe: Boolean = false
     }
 }
diff --git a/parsley/shared/src/main/scala/parsley/internal/deepembedding/backend/SequenceEmbedding.scala b/parsley/shared/src/main/scala/parsley/internal/deepembedding/backend/SequenceEmbedding.scala
@@ -111,7 +111,12 @@ private [deepembedding] final class >>=[A, B](val p: StrictParsley[A], private [
     }
     override def codeGen[M[_, +_]: ContOps, R](implicit instrs: InstrBuffer, state: CodeGenState): M[R, Unit] = {
         suspend(p.codeGen[M, R]) |> {
-            instrs += instructions.DynCall[A](x => f(x).demandCalleeSave(state.numRegs).instrs)
+            instrs += instructions.DynCall[A] { x =>
+                val p = f(x)
+                p.demandCalleeSave(state.numRegs)
+                if (implicitly[ContOps[M]].isStackSafe) p.overflows()
+                p.instrs
+            }
         }
     }
     // $COVERAGE-OFF$

diff --git a/parsley/shared/src/main/scala/parsley/internal/deepembedding/frontend/LazyParsley.scala b/parsley/shared/src/main/scala/parsley/internal/deepembedding/frontend/LazyParsley.scala
@@ -46,10 +46,7 @@ private [parsley] abstract class LazyParsley[+A] private [deepembedding] {
       *
       * @param numRegs the number of registers the parent uses (these must be saved)
       */
-    private [deepembedding] def demandCalleeSave(numRegs: Int): this.type = {
-        numRegsUsedByParent = numRegs
-        this
-    }
+    private [deepembedding] def demandCalleeSave(numRegs: Int): Unit = numRegsUsedByParent = numRegs
 
     // Internals
     // To ensure that stack-overflow cannot occur during the processing of particularly