Initial commit

csv.go

@@ -0,0 +1,49 @@
+package scriptx
+
+import (
+	"encoding/csv"
+	"errors"
+	"io"
+)
+
+func CSVColumn(name string) func(r io.Reader, w io.Writer) error {
+	return func(r io.Reader, w io.Writer) error {
+		cr := csv.NewReader(r)
+
+		header, err := cr.Read()
+		if err != nil {
+			return err
+		}
+
+		var colIdx = -1
+		for i, ch := range header {
+			if ch == name {
+				colIdx = i
+			}
+		}
+		if colIdx == -1 {
+			return nil
+		}
+
+		for {
+			rec, err := cr.Read()
+			if err != nil {
+				if errors.Is(err, io.EOF) {
+					return nil
+				} else {
+					return err
+				}
+			}
+			if len(rec) < colIdx {
+				continue
+			}
+
+			if _, err := io.WriteString(w, rec[colIdx]); err != nil {
+				return err
+			}
+			if _, err := w.Write([]byte{'\n'}); err != nil {
+				return err
+			}
+		}
+	}
+}