moved a subset of source file to the kern package

operand-func.go

@@ -6,15 +6,21 @@ package expr
 
 import (
 	"errors"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
 // -------- function call term
 func newFuncCallTerm(tk *Token, args []*term) *term {
+	var pos termPosition = posLeaf
+	if len(args) > 0 {
+		pos = posMultifix
+	}
 	return &term{
 		tk:       *tk,
 		parent:   nil,
 		children: args,
-		position: posLeaf,
+		position: pos,
 		priority: priValue,
 		evalFunc: evalFuncCall,
 	}
@@ -38,9 +44,9 @@ func newFuncCallTerm(tk *Token, args []*term) *term {
 // 	return
 // }
 
-func evalFuncCall(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalFuncCall(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	name, _ := opTerm.tk.Value.(string)
-	v, err = CallFunctionByTerm(ctx, name, opTerm)
+	v, err = kern.CallFunctionByTerm(ctx, name, opTerm)
 	return
 }
 
@@ -57,23 +63,23 @@ func newFuncDefTerm(tk *Token, args []*term) *term {
 }
 
 // -------- eval func def
-func evalFuncDef(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalFuncDef(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	bodySpec := opTerm.value()
-	if expr, ok := bodySpec.(*ast); ok {
-		paramList := make([]ExprFuncParam, 0, len(opTerm.children))
+	if ast, ok := bodySpec.(*ast); ok {
+		paramList := make([]kern.ExprFuncParam, 0, len(opTerm.children))
 		for _, param := range opTerm.children {
 			var defValue any
 			flags := paramFlags(0)
 			if len(param.children) > 0 {
 				flags |= PfDefault
-				if defValue, err = param.children[0].compute(ctx); err != nil {
+				if defValue, err = param.children[0].Compute(ctx); err != nil {
 					return
 				}
 			}
-			info := NewFuncParamFlagDef(param.source(), flags, defValue)
+			info := NewFuncParamFlagDef(param.Source(), flags, defValue)
 			paramList = append(paramList, info)
 		}
-		v = newExprFunctor(expr, paramList, ctx)
+		v = newExprFunctor(ast, paramList, ctx)
 	} else {
 		err = errors.New("invalid function definition: the body specification must be an expression")
 	}