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data-cursor.go: add item mapping support

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This commit is contained in:
Celestino Amoroso
2024-07-13 06:44:00 +02:00
parent 8547248ea2
commit 9a95a837f6
3 changed files with 59 additions and 29 deletions
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data-cursor.go
+54 -26
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@@ -133,39 +133,60 @@ func (dc *dataCursor) Current() (item any, err error) { // must return io.EOF at
return
}
func (dc *dataCursor) _Next() (item any, err error) { // must return io.EOF after the last item
if dc.resource != nil {
ctx := cloneContext(dc.ctx)
// fmt.Printf("Entering Inner-Ctx [%p]: %s\n", ctx, CtxToString(ctx, 0))
if item, err = dc.nextFunc.Invoke(ctx, nextName, []any{dc.resource}); err == nil {
if item == nil {
err = io.EOF
} else {
dc.index++
}
}
// fmt.Printf("Exiting Inner-Ctx [%p]: %s\n", ctx, CtxToString(ctx, 0))
exportObjects(dc.ctx, ctx)
// fmt.Printf("Outer-Ctx [%p]: %s\n", dc.ctx, CtxToString(dc.ctx, 0))
} else {
err = errInvalidDataSource()
// func (dc *dataCursor) _Next() (item any, err error) { // must return io.EOF after the last item
// if dc.resource != nil {
// ctx := cloneContext(dc.ctx)
// // fmt.Printf("Entering Inner-Ctx [%p]: %s\n", ctx, CtxToString(ctx, 0))
// if item, err = dc.nextFunc.Invoke(ctx, nextName, []any{dc.resource}); err == nil {
// if item == nil {
// err = io.EOF
// } else {
// dc.index++
// }
// }
// // fmt.Printf("Exiting Inner-Ctx [%p]: %s\n", ctx, CtxToString(ctx, 0))
// exportObjects(dc.ctx, ctx)
// // fmt.Printf("Outer-Ctx [%p]: %s\n", dc.ctx, CtxToString(dc.ctx, 0))
// } else {
// err = errInvalidDataSource()
// }
// return
// }
// func (dc *dataCursor) _filter(item any) (filterdItem any, err error) {
// if filter, ok := dc.ds[filterName]; ok {
// ctx := cloneContext(dc.ctx)
// filterdItem, err = filter.Invoke(ctx, filterName, []any{item, dc.index})
// } else {
// filterdItem = item
// }
// return
// }
func (dc *dataCursor) checkFilter(filter Functor, item any) (accepted bool, err error) {
var v any
var ok bool
ctx := cloneContext(dc.ctx)
if v, err = filter.Invoke(ctx, filterName, []any{item, dc.index}); err == nil && v != nil {
if accepted, ok = v.(bool); !ok {
accepted = true // NOTE: A non-boolean value that is not nil means the item has been accepted
}
}
return
}
const filterName = "filter"
func (dc *dataCursor) filter(item any) (filterdItem any, err error) {
if filter, ok := dc.ds[filterName]; ok {
ctx := cloneContext(dc.ctx)
filterdItem, err = filter.Invoke(ctx, filterName, []any{item, dc.index});
} else {
filterdItem = item
}
func (dc *dataCursor) mapItem(mapper Functor, item any) (mappedItem any, err error) {
ctx := cloneContext(dc.ctx)
mappedItem, err = mapper.Invoke(ctx, mapName, []any{item, dc.index});
return
}
func (dc *dataCursor) Next() (item any, err error) { // must return io.EOF after the last item
var accepted bool
if dc.resource != nil {
filter := dc.ds[filterName]
mapper := dc.ds[mapName]
for item == nil && err == nil {
ctx := cloneContext(dc.ctx)
if item, err = dc.nextFunc.Invoke(ctx, nextName, []any{dc.resource}); err == nil {
@@ -173,7 +194,14 @@ func (dc *dataCursor) Next() (item any, err error) { // must return io.EOF after
err = io.EOF
} else {
dc.index++
item, err = dc.filter(item)
if filter != nil {
if accepted, err = dc.checkFilter(filter, item); err != nil || !accepted {
item = nil
}
}
if item != nil && mapper != nil {
item, err = dc.mapItem(mapper, item)
}
}
}
exportObjects(dc.ctx, ctx)