Be smarter about auto-unflatten (#1584)

pkg/cli/flatten_unflatten.go

@@ -52,6 +52,10 @@ package cli
 // * If input is non-JSON and output is JSON:
 //   o Default is to auto-unflatten at output.
 //   o There is a --no-auto-unflatten for those who want it.
+//
+// * Overrriding these: if the last verb the user has explicitly provided is
+//   flatten, don't undo that by putting an unflatten right after.
+// 
 // ================================================================
 
 func DecideFinalFlatten(writerOptions *TWriterOptions) bool {
@@ -64,7 +68,22 @@ func DecideFinalFlatten(writerOptions *TWriterOptions) bool {
 	return false
 }
 
-func DecideFinalUnflatten(options *TOptions) bool {
+func DecideFinalUnflatten(
+	options *TOptions,
+    verbSequences [][]string,
+) bool {
+
+	numVerbs := len(verbSequences)
+	if numVerbs > 0 {
+		lastVerbSequence := verbSequences[numVerbs-1]
+		if len(lastVerbSequence) > 0 {
+			lastVerbName := lastVerbSequence[0]
+			if lastVerbName == "flatten" {
+				return false
+			}
+		}
+	}
+
 	ifmt := options.ReaderOptions.InputFileFormat
 	ofmt := options.WriterOptions.OutputFileFormat
 

pkg/climain/mlrcli_parse.go

@@ -376,7 +376,7 @@ func parseCommandLinePassTwo(
 		recordTransformers = append(recordTransformers, transformer)
 	}
 
-	if cli.DecideFinalUnflatten(options) {
+	if cli.DecideFinalUnflatten(options, verbSequences) {
 		// E.g.  req.method=GET,req.path=/api/check becomes
 		// '{"req": {"method": "GET", "path": "/api/check"}}'
 		transformer, err := transformers.NewTransformerUnflatten(options.WriterOptions.FLATSEP, options, nil)

pkg/terminals/repl/entry.go

@@ -156,7 +156,7 @@ func ReplMain(args []string) int {
 	// --auto-flatten is on by default. But if input and output formats are both JSON,
 	// then we don't need to actually do anything. See also mlrcli_parse.go.
 	options.WriterOptions.AutoFlatten = cli.DecideFinalFlatten(&options.WriterOptions)
-	options.WriterOptions.AutoUnflatten = cli.DecideFinalUnflatten(options)
+	options.WriterOptions.AutoUnflatten = cli.DecideFinalUnflatten(options, [][]string{})
 
 	recordOutputFileName := "(stdout)"
 	recordOutputStream := os.Stdout