file iterators refactored

builtin-os-file-iter-byte.go

@@ -5,9 +5,6 @@
 package expr
 
 import (
-	"fmt"
-	"slices"
-
 	"git.portale-stac.it/go-pkg/expr/file"
 	"git.portale-stac.it/go-pkg/expr/kern"
 )
@@ -15,15 +12,14 @@ import (
 const fileByteIteratorType = "fileByteIterator"
 
 type fileFileByteIterator struct {
-	reader    *file.Reader
-	index     int64
-	count     int64
-	b         byte
-	autoClose bool
+	fileIterBase
+	b byte
 }
 
 func newFileByteIterator(r *file.Reader, autoClose bool) *fileFileByteIterator {
-	return &fileFileByteIterator{reader: r, index: -1, autoClose: autoClose}
+	return &fileFileByteIterator{
+		fileIterBase: fileIterBase{reader: r, index: -1, count: 0, autoClose: autoClose},
+		b:            0}
 }
 
 func (it *fileFileByteIterator) TypeName() string {
@@ -31,20 +27,12 @@ func (it *fileFileByteIterator) TypeName() string {
 }
 
 func (it *fileFileByteIterator) String() string {
-	if it.reader.Valid() {
-		return fmt.Sprintf("$(%s@%q)", fileByteIteratorType, it.reader.GetName())
-	}
-	return fmt.Sprintf("$(%s@<nil>)", fileByteIteratorType)
-}
-
-func (it *fileFileByteIterator) Count() int64 {
-	return it.count
+	return it.repr(fileByteIteratorType)
 }
 
 func (it *fileFileByteIterator) Next() (item any, err error) { // must return io.EOF after the last item
 	if it.b, err = it.reader.ReadByte(); err == nil {
-		it.index++
-		it.count++
+		it.increment()
 		item = it.b
 	} else if it.autoClose {
 		it.Clean()
@@ -57,30 +45,23 @@ func (it *fileFileByteIterator) Current() (item any, err error) {
 	return
 }
 
-func (it *fileFileByteIterator) Index() int64 {
-	return it.index
-}
-
 func (it *fileFileByteIterator) Reset() (err error) {
 	if err = it.reader.Reset(); err == nil {
-		it.index = -1
-		it.count = 0
+		it.reset()
 		it.b = 0
 	}
 	return
 }
 
-func (it *fileFileByteIterator) HasOperation(name string) bool {
-	return slices.Contains([]string{kern.NextName, kern.ResetName, kern.IndexName, kern.CountName, kern.CurrentName, kern.CleanName}, name)
-}
-
 func (it *fileFileByteIterator) Clean() (err error) {
 	if it.reader.Valid() {
 		if err = it.reader.GetFile().Close(); err == nil {
 			it.reader = nil
 		}
 	}
-	return nil
+	it.reset()
+	it.b = 0
+	return
 }
 
 func (it *fileFileByteIterator) CallOperation(name string, args map[string]any) (v any, err error) {
@@ -108,8 +89,6 @@ func fileByteIteratorFunc(ctx kern.ExprContext, name string, args map[string]any
 	var invalidFileHandle any
 	var autoClose bool
 
-	result = nil
-
 	if handle, invalidFileHandle, autoClose, err = initFileHandle(ctx, name, args); err == nil {
 		if handle != nil {
 			result = newFileByteIterator(handle, autoClose)