Add a catch-all ErrInterrupted raiser.

eval/eval.go

@@ -264,6 +264,16 @@ func catch(perr *error, ec *EvalCtx) {
 	// function.
 	r := recover()
 	if r == nil {
+		// Ideally, all evaluation methods should keep an eye on ec.intCh and
+		// raise ErrInterrupted as soon as possible. However, this is quite
+		// tedious and only evaluation methods that may take an indefinite
+		// amount of time do this. The code below ensures that ErrInterrupted
+		// is always raised when there is an interrupt.
+		select {
+		case <-ec.intCh:
+			*perr = &util.PosError{ec.begin, ec.end, ErrInterrupted}
+		default:
+		}
 		return
 	}
 	if exc, ok := r.(util.Exception); ok {