Add TabWriter truncation and padding options

Inspired by kubectl's table output formatting, this adds TabWriterTruncate
config to control multiline handling in tab writer mode - when enabled,
truncates at first line break with "..."; when disabled, replaces break
characters with spaces. Also adds per-table DisableTableWriterTruncate
override and TableWriterPadding for leading whitespace. Includes handling
for form feed and carriage return characters.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: wpjunior

render.go

@@ -25,11 +25,15 @@ var TableConfig = struct {
 	ForceWrap    bool
 	UseTabWriter bool
 	MaxTTYWidth  int
+
+	TabWriterTruncate bool
 }{
 	BreakOnAny:   false,
 	ForceWrap:    false,
 	UseTabWriter: false,
 	MaxTTYWidth:  0,
+
+	TabWriterTruncate: true,
 }
 
 var ignoredPatterns = []*regexp.Regexp{
@@ -43,6 +47,9 @@ type Table struct {
 	Headers       Row
 	LineSeparator bool
 	rows          rowSlice
+
+	DisableTableWriterTruncate bool
+	TableWriterPadding         int
 }
 
 type Row []string
@@ -226,24 +233,40 @@ func getNewTabWriter(output io.Writer) *tabwriter.Writer {
 	return tabwriter.NewWriter(output, tabwriterMinWidth, tabwriterWidth, tabwriterPadding, tabwriterPadChar, 0)
 }
 
+var tableWriterReplacer = strings.NewReplacer(
+	"\f", " ",
+	"\n", " ",
+	"\r", " ",
+)
+
 func (t *Table) renderUsingTabWriter() string {
 	buf := bytes.NewBuffer(nil)
 	w := getNewTabWriter(buf)
+	padding := strings.Repeat(" ", t.TableWriterPadding)
 
 	if len(t.Headers) > 0 {
 		capitalizedHeaders := []string{}
 		for _, header := range t.Headers {
 			capitalizedHeaders = append(capitalizedHeaders, strings.ToUpper(header))
 		}
-		fmt.Fprintln(w, strings.Join(capitalizedHeaders, "\t"))
+		fmt.Fprintln(w, padding+strings.Join(capitalizedHeaders, "\t"))
 	}
 
 	for _, row := range t.rows {
 		newRow := make([]string, len(row))
 		for i, column := range row {
-			newRow[i] = strings.ReplaceAll(column, "\n", " ")
+			breakchar := strings.IndexAny(column, "\f\n\r")
+			if breakchar >= 0 {
+				if TableConfig.TabWriterTruncate && !t.DisableTableWriterTruncate {
+					column = column[:breakchar] + " ..."
+				} else {
+					column = tableWriterReplacer.Replace(column)
+				}
+			}
+
+			newRow[i] = column
 		}
-		fmt.Fprintln(w, strings.Join(newRow, "\t"))
+		fmt.Fprintln(w, padding+strings.Join(newRow, "\t"))
 	}
 	w.Flush()
 	return buf.String()

render_test.go

@@ -476,9 +476,122 @@ func TestStringTabWriterMultiline(t *testing.T) {
 	table.AddRow(Row{"One", "1", ""})
 	table.AddRow(Row{"Two", "xxx\nyyy", "aa|bb|cc|dd"})
 	table.AddRow(Row{"Three", "3", ""})
-	expected := `One     1         
-Two     xxx yyy   aa|bb|cc|dd
-Three   3         
+	expected := "One     1         \nTwo     xxx ...   aa|bb|cc|dd\nThree   3         \n"
+	assert.Equal(t, expected, table.String())
+}
+
+func TestStringTabWriterTruncateEnabled(t *testing.T) {
+	TableConfig.UseTabWriter = true
+	TableConfig.TabWriterTruncate = true
+	defer func() {
+		TableConfig.UseTabWriter = false
+		TableConfig.TabWriterTruncate = true
+	}()
+	table := NewTable()
+	table.Headers = Row{"Name", "Description"}
+	table.AddRow(Row{"Item1", "Single line"})
+	table.AddRow(Row{"Item2", "First line\nSecond line\nThird line"})
+	table.AddRow(Row{"Item3", "Another single"})
+	expected := `NAME    DESCRIPTION
+Item1   Single line
+Item2   First line ...
+Item3   Another single
+`
+	assert.Equal(t, expected, table.String())
+}
+
+func TestStringTabWriterTruncateDisabled(t *testing.T) {
+	TableConfig.UseTabWriter = true
+	TableConfig.TabWriterTruncate = false
+	defer func() {
+		TableConfig.UseTabWriter = false
+		TableConfig.TabWriterTruncate = true
+	}()
+	table := NewTable()
+	table.Headers = Row{"Name", "Description"}
+	table.AddRow(Row{"Item1", "Single line"})
+	table.AddRow(Row{"Item2", "First line\nSecond line"})
+	table.AddRow(Row{"Item3", "Another single"})
+	expected := `NAME    DESCRIPTION
+Item1   Single line
+Item2   First line Second line
+Item3   Another single
+`
+	assert.Equal(t, expected, table.String())
+}
+
+func TestStringTabWriterDisableTableTruncate(t *testing.T) {
+	TableConfig.UseTabWriter = true
+	TableConfig.TabWriterTruncate = true
+	defer func() {
+		TableConfig.UseTabWriter = false
+		TableConfig.TabWriterTruncate = true
+	}()
+	table := NewTable()
+	table.DisableTableWriterTruncate = true
+	table.Headers = Row{"Name", "Description"}
+	table.AddRow(Row{"Item1", "Single line"})
+	table.AddRow(Row{"Item2", "First line\nSecond line"})
+	expected := `NAME    DESCRIPTION
+Item1   Single line
+Item2   First line Second line
+`
+	assert.Equal(t, expected, table.String())
+}
+
+func TestStringTabWriterPadding(t *testing.T) {
+	TableConfig.UseTabWriter = true
+	defer func() {
+		TableConfig.UseTabWriter = false
+	}()
+	table := NewTable()
+	table.TableWriterPadding = 2
+	table.Headers = Row{"Word", "Number"}
+	table.AddRow(Row{"One", "1"})
+	table.AddRow(Row{"Two", "2"})
+	expected := `  WORD   NUMBER
+  One    1
+  Two    2
+`
+	assert.Equal(t, expected, table.String())
+}
+
+func TestStringTabWriterFormFeedAndCarriageReturn(t *testing.T) {
+	TableConfig.UseTabWriter = true
+	TableConfig.TabWriterTruncate = true
+	defer func() {
+		TableConfig.UseTabWriter = false
+		TableConfig.TabWriterTruncate = true
+	}()
+	table := NewTable()
+	table.Headers = Row{"Name", "Value"}
+	table.AddRow(Row{"FormFeed", "before\fafter"})
+	table.AddRow(Row{"CarriageReturn", "before\rafter"})
+	table.AddRow(Row{"Mixed", "a\fb\nc\rd"})
+	expected := `NAME             VALUE
+FormFeed         before ...
+CarriageReturn   before ...
+Mixed            a ...
+`
+	assert.Equal(t, expected, table.String())
+}
+
+func TestStringTabWriterFormFeedAndCarriageReturnNoTruncate(t *testing.T) {
+	TableConfig.UseTabWriter = true
+	TableConfig.TabWriterTruncate = false
+	defer func() {
+		TableConfig.UseTabWriter = false
+		TableConfig.TabWriterTruncate = true
+	}()
+	table := NewTable()
+	table.Headers = Row{"Name", "Value"}
+	table.AddRow(Row{"FormFeed", "before\fafter"})
+	table.AddRow(Row{"CarriageReturn", "before\rafter"})
+	table.AddRow(Row{"Mixed", "a\fb\nc\rd"})
+	expected := `NAME             VALUE
+FormFeed         before after
+CarriageReturn   before after
+Mixed            a b c d
 `
 	assert.Equal(t, expected, table.String())
 }