Added csv, tsv output formats

pkg/yqlib/encoder_csv.go

@@ -0,0 +1,38 @@
+package yqlib
+
+import (
+	"encoding/csv"
+	"fmt"
+	"io"
+
+	yaml "gopkg.in/yaml.v3"
+)
+
+type csvEncoder struct {
+	destination csv.Writer
+}
+
+func NewCsvEncoder(destination io.Writer, separator rune) Encoder {
+	csvWriter := *csv.NewWriter(destination)
+	csvWriter.Comma = separator
+	return &csvEncoder{csvWriter}
+}
+
+func (e *csvEncoder) Encode(originalNode *yaml.Node) error {
+	// node must be a sequence
+	node := unwrapDoc(originalNode)
+	if node.Kind != yaml.SequenceNode {
+		return fmt.Errorf("csv encoding only works for arrays of scalars (string/numbers/booleans), got: %v", node.Tag)
+	}
+
+	stringValues := make([]string, len(node.Content))
+
+	for i, child := range node.Content {
+
+		if child.Kind != yaml.ScalarNode {
+			return fmt.Errorf("csv encoding only works for arrays of scalars (string/numbers/booleans), child[%v] is a %v", i, child.Tag)
+		}
+		stringValues[i] = child.Value
+	}
+	return e.destination.Write(stringValues)
+}