Split printer

cmd/constant.go

@@ -21,4 +21,6 @@ var prettyPrint = false
 // can be either "" (off), "extract" or "process"
 var frontMatter = ""
 
+var splitFileExp = ""
+
 var completedSuccessfully = false

cmd/evaluate_all_command.go

@@ -70,6 +70,10 @@ func evaluateAll(cmd *cobra.Command, args []string) error {
 		return fmt.Errorf("Write inplace flag only applicable when giving an expression and at least one file")
 	}
 
+	if writeInplace && splitFileExp != "" {
+		return fmt.Errorf("Write inplace cannot be used with split file")
+	}
+
 	if writeInplace {
 		// only use colors if its forced
 		colorsEnabled = forceColor
@@ -96,7 +100,9 @@ func evaluateAll(cmd *cobra.Command, args []string) error {
 		return err
 	}
 
-	printer := yqlib.NewPrinter(out, format, unwrapScalar, colorsEnabled, indent, !noDocSeparators)
+	printerWriter := configurePrinterWriter(format, out)
+
+	printer := yqlib.NewPrinter(printerWriter, format, unwrapScalar, colorsEnabled, indent, !noDocSeparators)
 
 	if frontMatter != "" {
 		frontMatterHandler := yqlib.NewFrontMatterHandler(args[firstFileIndex])

cmd/evalute_sequence_command.go

@@ -83,6 +83,10 @@ func evaluateSequence(cmd *cobra.Command, args []string) error {
 		return fmt.Errorf("Write inplace flag only applicable when giving an expression and at least one file")
 	}
 
+	if writeInplace && splitFileExp != "" {
+		return fmt.Errorf("Write inplace cannot be used with split file")
+	}
+
 	if writeInplace {
 		// only use colors if its forced
 		colorsEnabled = forceColor
@@ -106,7 +110,9 @@ func evaluateSequence(cmd *cobra.Command, args []string) error {
 		return err
 	}
 
-	printer := yqlib.NewPrinter(out, format, unwrapScalar, colorsEnabled, indent, !noDocSeparators)
+	printerWriter := configurePrinterWriter(format, out)
+
+	printer := yqlib.NewPrinter(printerWriter, format, unwrapScalar, colorsEnabled, indent, !noDocSeparators)
 
 	streamEvaluator := yqlib.NewStreamEvaluator()
 

cmd/printer_utils.go

@@ -0,0 +1,24 @@
+package cmd
+
+import (
+	"io"
+
+	"github.com/mikefarah/yq/v4/pkg/yqlib"
+)
+
+func configurePrinterWriter(format yqlib.PrinterOutputFormat, out io.Writer) yqlib.PrinterWriter {
+
+	var printerWriter yqlib.PrinterWriter
+
+	if splitFileExp != "" {
+		colorsEnabled = forceColor
+		splitExp, err := yqlib.NewExpressionParser().ParseExpression(splitFileExp)
+		if err != nil {
+			return nil
+		}
+		printerWriter = yqlib.NewMultiPrinterWriter(splitExp, format)
+	} else {
+		printerWriter = yqlib.NewSinglePrinterWriter(out)
+	}
+	return printerWriter
+}

cmd/root.go

@@ -63,6 +63,9 @@ See https://mikefarah.gitbook.io/yq/ for detailed documentation and examples.`,
 	rootCmd.PersistentFlags().BoolVarP(&forceNoColor, "no-colors", "M", false, "force print with no colors")
 	rootCmd.PersistentFlags().StringVarP(&frontMatter, "front-matter", "f", "", "(extract|process) first input as yaml front-matter. Extract will pull out the yaml content, process will run the expression against the yaml content, leaving the remaining data intact")
 	rootCmd.PersistentFlags().BoolVarP(&leadingContentPreProcessing, "header-preprocess", "", true, "Slurp any header comments and separators before processing expression. This is a workaround for go-yaml to persist header content properly.")
+
+	rootCmd.PersistentFlags().StringVarP(&splitFileExp, "split-exp", "s", "", "print each result (or doc) into a file named (exp). [exp] argument must return a string. You can use $index in the expression as the result counter.")
+
 	rootCmd.AddCommand(
 		createEvaluateSequenceCommand(),
 		createEvaluateAllCommand(),