Small opts + halt

Common/src/main/java/at/petrak/hexcasting/api/spell/casting/ContinuationFrame.kt

@@ -6,7 +6,7 @@ import at.petrak.hexcasting.api.spell.casting.CastingHarness.CastResult
 import net.minecraft.server.level.ServerLevel
 
 /**
- * A single frame of evaluation during the 
+ * A single frame of evaluation during the execution of a spell.
  */
 sealed interface ContinuationFrame {
     fun evaluate(continuation: MutableList<ContinuationFrame>, level: ServerLevel, harness: CastingHarness): CastResult

Common/src/main/java/at/petrak/hexcasting/common/casting/operators/eval/OpEval.kt

@@ -17,7 +17,10 @@ object OpEval : Operator {
 
         ctx.incDepth()
 
-        continuation.add(ContinuationFrame.FinishEval()) // boundary for break
+        // if not installed already...
+        if (!(continuation.isNotEmpty() && continuation.last() is ContinuationFrame.FinishEval)) {
+            continuation.add(ContinuationFrame.FinishEval()) // install a break-boundary after eval
+        }
         continuation.add(ContinuationFrame.Evaluate(instrs))
 
         return OperationResult(stack, local, listOf())

Common/src/main/java/at/petrak/hexcasting/common/casting/operators/eval/OpHalt.kt

@@ -0,0 +1,31 @@
+package at.petrak.hexcasting.common.casting.operators.eval
+
+import at.petrak.hexcasting.api.spell.OperationResult
+import at.petrak.hexcasting.api.spell.Operator
+import at.petrak.hexcasting.api.spell.getChecked
+import at.petrak.hexcasting.api.spell.SpellDatum
+import at.petrak.hexcasting.api.spell.SpellList
+import at.petrak.hexcasting.api.spell.casting.CastingContext
+import at.petrak.hexcasting.api.spell.casting.CastingHarness
+import at.petrak.hexcasting.api.spell.casting.ContinuationFrame
+import at.petrak.hexcasting.api.spell.casting.OperatorSideEffect
+
+object OpHalt : Operator {
+    override fun operate(continuation: MutableList<ContinuationFrame>, stack: MutableList<SpellDatum<*>>, local: SpellDatum<*>, ctx: CastingContext): OperationResult {
+        var newStack = stack
+        var done = false
+        while (!done && continuation.isNotEmpty() && !done) {
+            // Kotlin Y U NO destructuring assignment
+            val newInfo = continuation.removeLast().breakDownwards(newStack)
+            newStack = newInfo.first
+            done = newInfo.second
+        }
+        // if we hit no continuation boundaries (i.e. thoth/hermes exits), we've TOTALLY cleared the itinerary...
+        if (!done) {
+            // bomb the stack so we exit
+            newStack = listOf()
+        }
+
+        return OperationResult(newStack, local, listOf())
+    }
+}