moved a subset of source file to the kern package

operator-sign.go

@@ -4,6 +4,10 @@
 // operator-sign.go
 package expr
 
+import (
+	"git.portale-stac.it/go-pkg/expr/kern"
+)
+
 //-------- plus sign term
 
 func newPlusSignTerm(tk *Token) (inst *term) {
@@ -28,21 +32,21 @@ func newMinusSignTerm(tk *Token) (inst *term) {
 	}
 }
 
-func evalSign(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalSign(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var rightValue any
 
 	if rightValue, err = opTerm.evalPrefix(ctx); err != nil {
 		return
 	}
 
-	if IsFloat(rightValue) {
+	if kern.IsFloat(rightValue) {
 		if opTerm.tk.Sym == SymChangeSign {
 			f, _ := rightValue.(float64)
 			v = -f
 		} else {
 			v = rightValue
 		}
-	} else if IsInteger(rightValue) {
+	} else if kern.IsInteger(rightValue) {
 		if opTerm.tk.Sym == SymChangeSign {
 			i, _ := rightValue.(int64)
 			v = -i
@@ -50,7 +54,7 @@ func evalSign(ctx ExprContext, opTerm *term) (v any, err error) {
 			v = rightValue
 		}
 	} else {
-		err = opTerm.errIncompatibleType(rightValue)
+		err = opTerm.errIncompatiblePrefixPostfixType(rightValue)
 	}
 	return
 }