Function call moved from operand-func.go to function.go

function.go

@@ -199,3 +199,42 @@ func (info *funcInfo) MaxArgs() int {
 func (info *funcInfo) Functor() Functor {
 	return info.functor
 }
+
+// ----- Call a function ---
+
+func checkFunctionCall(ctx ExprContext, name string, varParams *[]any) (err error) {
+	if info, exists, owner := GetFuncInfo(ctx, name); exists {
+		passedCount := len(*varParams)
+		if info.MinArgs() > passedCount {
+			err = ErrTooFewParams(name, info.MinArgs(), info.MaxArgs(), passedCount)
+		}
+		for i, p := range info.Params() {
+			if i >= passedCount {
+				if !p.IsDefault() {
+					break
+				}
+				*varParams = append(*varParams, p.DefaultValue())
+			}
+		}
+		if err == nil && info.MaxArgs() >= 0 && info.MaxArgs() < len(*varParams) {
+			err = ErrTooMuchParams(name, info.MaxArgs(), len(*varParams))
+		}
+		if err == nil && owner != ctx {
+			ctx.RegisterFuncInfo(info)
+		}
+	} else {
+		err = fmt.Errorf("unknown function %s()", name)
+	}
+	return
+}
+
+func CallFunction(parentCtx ExprContext, name string, params []any) (result any, err error) {
+	ctx := cloneContext(parentCtx)
+	ctx.SetParent(parentCtx)
+
+	if err = checkFunctionCall(ctx, name, &params); err == nil {
+		result, err = ctx.Call(name, params)
+		exportObjectsToParent(ctx)
+	}
+	return
+}