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begin work on reflection-based scanner
Signed-off-by: oppiliappan <me@oppi.li>
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scanner.go
+60
scanner.go
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package norm
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import (
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"database/sql"
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"iter"
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"reflect"
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)
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type Scanner[T any] struct {
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rows *sql.Rows
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onError func(err error)
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}
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type ScannerOpt[T any] func(*Scanner[T])
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func OnScannerError[T any](errFunc func(error)) ScannerOpt[T] {
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return func(s *Scanner[T]) {
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s.onError = errFunc
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}
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}
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func NewScanner[T any](rows *sql.Rows, opts ...ScannerOpt[T]) Scanner[T] {
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scanner := Scanner[T]{
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rows: rows,
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}
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for _, o := range opts {
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o(&scanner)
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}
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return scanner
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}
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func (s *Scanner[T]) Scan() iter.Seq[T] {
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return func(yield func(T) bool) {
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defer s.rows.Close()
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for s.rows.Next() {
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var data T
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elem := reflect.ValueOf(&data).Elem()
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numCols := elem.NumField()
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columns := make([]any, numCols)
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for i := range numCols {
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field := elem.Field(i)
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columns[i] = field.Addr().Interface()
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}
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if err := s.rows.Scan(columns...); err != nil {
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s.onError(err)
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return
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}
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// Yield the row - if yield returns false, stop iteration
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if !yield(data) {
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return
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}
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}
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}
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}