added other CSV functions

csv.go

@@ -3,8 +3,10 @@ package scriptx
 import (
 	"bufio"
 	"encoding/csv"
+	"encoding/json"
 	"errors"
 	"io"
+	"sort"
 )
 
 type Splitter interface {
@@ -79,3 +81,162 @@ func CSVColumn(name string) func(r io.Reader, w io.Writer) error {
 		}
 	}
 }
+
+type CSVHeader struct {
+	header []string
+}
+
+func (ch *CSVHeader) Column(name string) int {
+	for c, h := range ch.header {
+		if h == name {
+			return c
+		}
+	}
+	return -1
+}
+
+func (ch *CSVHeader) Value(row []string, name string) string {
+	c := ch.Column(name)
+	if c == -1 || c >= len(row) {
+		return ""
+	}
+	return row[c]
+}
+
+func CSVFilter(fn func(row []string, header *CSVHeader) []string) func(io.Reader, io.Writer) error {
+	return func(r io.Reader, w io.Writer) error {
+		csvr := csv.NewReader(r)
+		csvr.FieldsPerRecord = 0
+
+		csvWriter := csv.NewWriter(w)
+
+		header, rErr := csvr.Read()
+		if rErr != nil {
+			return rErr
+		}
+		if err := csvWriter.Write(header); err != nil {
+			return err
+		}
+		headerInfo := CSVHeader{header: header}
+
+		row, rErr := csvr.Read()
+		for !errors.Is(rErr, io.EOF) {
+			newRow := fn(row, &headerInfo)
+			if newRow != nil {
+				if err := csvWriter.Write(newRow); err != nil {
+					return err
+				}
+			}
+
+			row, rErr = csvr.Read()
+		}
+		if rErr != nil && !errors.Is(rErr, io.EOF) {
+			return rErr
+		}
+
+		csvWriter.Flush()
+		return nil
+	}
+}
+
+func CSVSort(lessThan func(row1, row2 []string, header *CSVHeader) bool) func(io.Reader, io.Writer) error {
+	return func(r io.Reader, w io.Writer) error {
+		csvr := csv.NewReader(r)
+		csvr.FieldsPerRecord = 0
+
+		header, rErr := csvr.Read()
+		if rErr != nil {
+			return rErr
+		}
+		headerInfo := CSVHeader{header: header}
+
+		records, rErr := csvr.ReadAll()
+		if rErr != nil {
+			return rErr
+		}
+
+		sort.Slice(records, func(i, j int) bool {
+			return lessThan(records[i], records[j], &headerInfo)
+		})
+
+		csvWriter := csv.NewWriter(w)
+
+		if err := csvWriter.Write(header); err != nil {
+			return err
+		}
+		for _, r := range records {
+			if err := csvWriter.Write(r); err != nil {
+				return err
+			}
+		}
+
+		csvWriter.Flush()
+		return nil
+	}
+}
+
+func CSVMapToString(fn func(row []string, header *CSVHeader) string) func(io.Reader, io.Writer) error {
+	return func(r io.Reader, w io.Writer) error {
+		csvr := csv.NewReader(r)
+		csvr.FieldsPerRecord = 0
+
+		header, rErr := csvr.Read()
+		if rErr != nil {
+			return rErr
+		}
+		headerInfo := CSVHeader{header: header}
+
+		row, rErr := csvr.Read()
+		for !errors.Is(rErr, io.EOF) {
+			line := fn(row, &headerInfo)
+			if _, err := io.WriteString(w, line); err != nil {
+				return err
+			}
+			if _, err := io.WriteString(w, "\n"); err != nil {
+				return err
+			}
+
+			row, rErr = csvr.Read()
+		}
+		if rErr != nil && !errors.Is(rErr, io.EOF) {
+			return rErr
+		}
+
+		return nil
+	}
+}
+
+func CSVMapToJSON(fn func(row []string, header *CSVHeader) any) func(io.Reader, io.Writer) error {
+	return func(r io.Reader, w io.Writer) error {
+		csvr := csv.NewReader(r)
+		csvr.FieldsPerRecord = 0
+
+		header, rErr := csvr.Read()
+		if rErr != nil {
+			return rErr
+		}
+		headerInfo := CSVHeader{header: header}
+
+		row, rErr := csvr.Read()
+		for !errors.Is(rErr, io.EOF) {
+			obj := fn(row, &headerInfo)
+			jsonBytes, err := json.Marshal(obj)
+			if err != nil {
+				return err
+			}
+			if _, err = w.Write(jsonBytes); err != nil {
+				return err
+			}
+			if _, err := io.WriteString(w, "\n"); err != nil {
+				return err
+			}
+
+			row, rErr = csvr.Read()
+		}
+		if rErr != nil && !errors.Is(rErr, io.EOF) {
+			return rErr
+		}
+
+		return nil
+	}
+}

csv_test.go

@@ -57,3 +57,26 @@ func ExampleToCSV() {
 	// b,banana,bravo
 	// c,cherry,charlie
 }
+
+func ExampleCSVMapToJSON() {
+	script.Slice([]string{
+		"letter,fruit,word",
+		"a,apple,alpha",
+		"b,banana,bravo",
+		"c,cherry,charlie",
+	}).Filter(scriptx.CSVMapToJSON(func(row []string, header *scriptx.CSVHeader) any {
+		return struct {
+			Letter string `json:"letter"`
+			Fruit  string `json:"fruit"`
+			Word   string `json:"word"`
+		}{
+			Letter: header.Value(row, "letter"),
+			Fruit:  header.Value(row, "fruit"),
+			Word:   header.Value(row, "word"),
+		}
+	})).Stdout()
+	// Output:
+	// {"letter":"a","fruit":"apple","word":"alpha"}
+	// {"letter":"b","fruit":"banana","word":"bravo"}
+	// {"letter":"c","fruit":"cherry","word":"charlie"}
+}