From ce23dfd317c2f605747e6a98c760d99aba9a0877 Mon Sep 17 00:00:00 2001
From: John Kerl <kerl.john.r@gmail.com>
Date: Mon, 16 Nov 2020 22:15:31 -0500
Subject: [PATCH] record_writer_csvlite.go

---
 go/src/miller/cli/mlrcli_parse.go             | 25 ++---
 go/src/miller/output/record_writer_csvlite.go | 91 +++++++++++++++++++
 go/src/miller/output/record_writer_factory.go |  2 +
 3 files changed, 106 insertions(+), 12 deletions(-)
 create mode 100644 go/src/miller/output/record_writer_csvlite.go

diff --git a/go/src/miller/cli/mlrcli_parse.go b/go/src/miller/cli/mlrcli_parse.go
index 91a044877..2b45e68c9 100644
--- a/go/src/miller/cli/mlrcli_parse.go
+++ b/go/src/miller/cli/mlrcli_parse.go
@@ -568,7 +568,7 @@ func parseWriterOptions(args []string, argc int, pargi *int, writerOptions *clit
 		argi += 1
 
 	} else if args[argi] == "--ocsvlite" {
-		writerOptions.OutputFileFormat = "csv"
+		writerOptions.OutputFileFormat = "csvlite"
 		argi += 1
 
 	} else if args[argi] == "--otsv" {
@@ -576,11 +576,11 @@ func parseWriterOptions(args []string, argc int, pargi *int, writerOptions *clit
 		writerOptions.OFS = "\t"
 		argi += 1
 
-		//	} else if args[argi] == "--otsvlite" {
-		//		writerOptions.OutputFileFormat = "csvlite";
-		//		writerOptions.OFS = "\t";
-		//		argi += 1;
-		//
+	} else if args[argi] == "--otsvlite" {
+		writerOptions.OutputFileFormat = "csvlite"
+		writerOptions.OFS = "\t"
+		argi += 1
+
 		//	} else if args[argi] == "--oasv" {
 		//		writerOptions.OutputFileFormat = "csv";
 		//		writerOptions.OFS = ASV_FS;
@@ -738,12 +738,13 @@ func parseReaderWriterOptions(
 		writerOptions.OFS = "\t"
 		argi += 1
 
-		//	} else if args[argi] == "--tsvlite" || args[argi] == "-t" {
-		//		readerOptions.InputFileFormat = writerOptions.OutputFileFormat = "csvlite";
-		//		readerOptions.IFS = "\t";
-		//		writerOptions.OFS = "\t";
-		//		argi += 1;
-		//
+	} else if args[argi] == "--tsvlite" || args[argi] == "-t" {
+		readerOptions.InputFileFormat = "csvlite"
+		writerOptions.OutputFileFormat = "csvlite"
+		readerOptions.IFS = "\t"
+		writerOptions.OFS = "\t"
+		argi += 1
+
 		//	} else if args[argi] == "--asv" {
 		//		readerOptions.InputFileFormat = writerOptions.OutputFileFormat = "csv";
 		//		readerOptions.IFS = ASV_FS;
diff --git a/go/src/miller/output/record_writer_csvlite.go b/go/src/miller/output/record_writer_csvlite.go
new file mode 100644
index 000000000..da59c4e98
--- /dev/null
+++ b/go/src/miller/output/record_writer_csvlite.go
@@ -0,0 +1,91 @@
+package output
+
+import (
+	"bytes"
+	"os"
+	"strings"
+
+	"miller/clitypes"
+	"miller/types"
+)
+
+type RecordWriterCSVLite struct {
+	ofs string
+	ors string
+
+	doHeaderlessOutput bool
+	// For reporting schema changes: we print a newline and the new header
+	lastJoinedHeader *string
+	// Only write one blank line for schema changes / blank input lines
+	justWroteEmptyLine bool
+}
+
+func NewRecordWriterCSVLite(writerOptions *clitypes.TWriterOptions) *RecordWriterCSVLite {
+
+	return &RecordWriterCSVLite{
+		ofs: writerOptions.OFS,
+		ors: writerOptions.ORS,
+
+		doHeaderlessOutput: writerOptions.HeaderlessCSVOutput,
+		lastJoinedHeader:   nil,
+		justWroteEmptyLine: false,
+	}
+}
+
+func (this *RecordWriterCSVLite) Write(
+	outrec *types.Mlrmap,
+) {
+	// End of record stream: nothing special for this output format
+	if outrec == nil {
+		return
+	}
+
+	if outrec.FieldCount == 0 {
+		if !this.justWroteEmptyLine {
+			os.Stdout.WriteString("\n")
+		}
+		joinedHeader := ""
+		this.lastJoinedHeader = &joinedHeader
+		this.justWroteEmptyLine = true
+		return
+	}
+
+	needToPrintHeader := false
+	joinedHeader := strings.Join(outrec.GetKeys(), ",")
+	if this.lastJoinedHeader == nil || *this.lastJoinedHeader != joinedHeader {
+		if this.lastJoinedHeader != nil {
+			if !this.justWroteEmptyLine {
+				os.Stdout.WriteString("\n")
+			}
+			this.justWroteEmptyLine = true
+		}
+		this.lastJoinedHeader = &joinedHeader
+		needToPrintHeader = true
+	}
+
+	if needToPrintHeader && !this.doHeaderlessOutput {
+		var buffer bytes.Buffer // faster than fmt.Print() separately
+		for pe := outrec.Head; pe != nil; pe = pe.Next {
+			buffer.WriteString(*pe.Key)
+
+			if pe.Next != nil {
+				buffer.WriteString(this.ofs)
+			}
+		}
+
+		buffer.WriteString(this.ors)
+		os.Stdout.WriteString(buffer.String())
+	}
+
+	var buffer bytes.Buffer // faster than fmt.Print() separately
+	for pe := outrec.Head; pe != nil; pe = pe.Next {
+		buffer.WriteString(pe.Value.String())
+		if pe.Next != nil {
+			buffer.WriteString(this.ofs)
+		}
+	}
+	buffer.WriteString(this.ors)
+	os.Stdout.WriteString(buffer.String())
+
+	this.justWroteEmptyLine = false
+}
diff --git a/go/src/miller/output/record_writer_factory.go b/go/src/miller/output/record_writer_factory.go
index 564cfcb59..bd52734ad 100644
--- a/go/src/miller/output/record_writer_factory.go
+++ b/go/src/miller/output/record_writer_factory.go
@@ -8,6 +8,8 @@ func Create(writerOptions *clitypes.TWriterOptions) IRecordWriter {
 	switch writerOptions.OutputFileFormat {
 	case "csv":
 		return NewRecordWriterCSV(writerOptions)
+	case "csvlite":
+		return NewRecordWriterCSVLite(writerOptions)
 	case "dkvp":
 		return NewRecordWriterDKVP(writerOptions)
 	case "json":