bug fix as errors aren't hashable anymore, adding missing null for js…

…on to object, reduced stack limit, see comment; improve Stack() implementation (a lot) (#185)

README.md

@@ -197,7 +197,7 @@ flags:
   -history file
     	history file to use (default "~/.grol_history")
   -max-depth int
-    	Maximum interpreter depth (default 249999)
+    	Maximum interpreter depth (default 194999)
   -max-history size
     	max history size, use 0 to disable. (default 99)
   -max-save-len int

eval/eval_api.go

@@ -14,7 +14,11 @@ import (
 
 // Exported part of the eval package.
 
-const DefaultMaxDepth = 250_000
+// Approximate maximum depth of recursion to avoid:
+// runtime: goroutine stack exceeds 1000000000-byte limit
+// fatal error: stack overflow. Was 250k but adding a log
+// in Error() makes it go over that (somehow).
+const DefaultMaxDepth = 195_000
 
 type State struct {
 	Out        io.Writer

eval/stack.go

@@ -9,24 +9,25 @@ import (
 
 // Returns a stack array of the current stack.
 func (s *State) Stack() []string {
-	stack := make([]string, 0, s.depth) // will be -1 because no name at toplevel but... it's fine.
-	e := s.env
-	for {
-		if e == nil {
-			break
-		}
+	if s.depth <= 1 {
+		return nil
+	}
+	stack := make([]string, 0, s.depth-1)
+	for e := s.env; e != nil; e = e.StackParent() {
 		n := e.Name()
 		if n != "" {
 			stack = append(stack, e.Name())
 		}
-		e = e.StackParent()
 	}
 	log.Debugf("Stack() len %d, depth %d returning %v", len(stack), s.depth, stack)
 	return stack
 }
 
 // Creates a new error object with the given message and stack.
 func (s *State) Error(msg string) object.Error {
+	if log.LogDebug() {
+		log.LogVf("Error %q called", msg)
+	}
 	return object.Error{Value: msg, Stack: s.Stack()}
 }
 

examples/pi2.gr

@@ -9,5 +9,5 @@ f = func(i, n, prod) {
 	}
 	self(i+1, n, prod*(1-1./(2*i)))
 }
-n = 200_000
+n = 194_990 // close to 195_000 default limit.
 f(1, n, 1)

extensions/extension.go

@@ -97,6 +97,7 @@ func initInternal(c *Config) error { //nolint:funlen,gocognit,gocyclo,maintidx /
 		return err
 	}
 	object.AddIdentifier("nil", object.NULL)
+	object.AddIdentifier("null", object.NULL)
 	object.AddIdentifier("NaN", object.Float{Value: math.NaN()})
 	object.AddIdentifier("Inf", object.Float{Value: math.Inf(0)}) // Works for both -Inf and +Inf (thanks to noop unary +).
 

object/object.go

@@ -8,6 +8,7 @@ import (
 	"strconv"
 	"strings"
 
+	"fortio.org/log"
 	"grol.io/grol/ast"
 	"grol.io/grol/token"
 )
@@ -59,7 +60,7 @@ type Number interface {
 // Hashable in tem of Go map for cache key.
 func Hashable(o Object) bool {
 	switch o.Type() { //nolint:exhaustive // We have all the types that are hashable + default for the others.
-	case INTEGER, FLOAT, BOOLEAN, NIL, ERROR, STRING:
+	case INTEGER, FLOAT, BOOLEAN, NIL, STRING:
 		return true
 	case ARRAY:
 		if sa, ok := o.(SmallArray); ok {
@@ -80,6 +81,7 @@ func Hashable(o Object) bool {
 			return true
 		}
 	}
+	log.Debugf("Not hashable: %#v", o)
 	return false
 }