From 080e6dc7379714f64450b81e88bc82e4d22c9640 Mon Sep 17 00:00:00 2001
From: upstream <upstream@localhost>
Date: Wed, 2 Sep 2026 09:44:11 +0200
Subject: [PATCH] Upstream charmbracelet/lipgloss state of the touched files
 before 1a8841c478

---
 whitespace.go      | 76 ++++++++++++++++++++++++++++++++++++++++++++++
 whitespace_test.go | 52 +++++++++++++++++++++++++++++++
 2 files changed, 128 insertions(+)
 create mode 100644 whitespace.go
 create mode 100644 whitespace_test.go

diff --git a/whitespace.go b/whitespace.go
new file mode 100644
index 0000000..e353a07
--- /dev/null
+++ b/whitespace.go
@@ -0,0 +1,76 @@
+package lipgloss
+
+import (
+	"strings"
+
+	"github.com/charmbracelet/x/ansi"
+)
+
+// whitespace is a whitespace renderer.
+type whitespace struct {
+	chars string
+	style Style
+}
+
+// newWhitespace creates a new whitespace renderer.
+func newWhitespace(opts ...WhitespaceOption) *whitespace {
+	w := &whitespace{}
+	for _, opt := range opts {
+		opt(w)
+	}
+	return w
+}
+
+// Render whitespaces.
+func (w whitespace) render(width int) string {
+	if w.chars == "" {
+		w.chars = " "
+	}
+
+	r := []rune(w.chars)
+	j := 0
+	b := strings.Builder{}
+
+	// Cycle through runes and print them into the whitespace.
+	for i := 0; i < width; {
+		b.WriteRune(r[j])
+		// Measure the width of the rune we just wrote, ensuring we always
+		// make progress to avoid infinite loops with zero-width characters
+		// like tabs.
+		runeWidth := ansi.StringWidth(string(r[j]))
+		if runeWidth < 1 {
+			runeWidth = 1
+		}
+		i += runeWidth
+		j++
+		if j >= len(r) {
+			j = 0
+		}
+	}
+
+	// Fill any extra gaps white spaces. This might be necessary if any runes
+	// are more than one cell wide, which could leave a one-rune gap.
+	short := width - ansi.StringWidth(b.String())
+	if short > 0 {
+		b.WriteString(strings.Repeat(" ", short))
+	}
+
+	return w.style.Render(b.String())
+}
+
+// WhitespaceOption sets a styling rule for rendering whitespace.
+type WhitespaceOption func(*whitespace)
+
+// WithWhitespaceStyle sets the style for the whitespace.
+func WithWhitespaceStyle(s Style) WhitespaceOption {
+	return func(w *whitespace) {
+		w.style = s
+	}
+}
+
+// WithWhitespaceChars sets the characters to be rendered in the whitespace.
+func WithWhitespaceChars(s string) WhitespaceOption {
+	return func(w *whitespace) {
+		w.chars = s
+	}
+}
diff --git a/whitespace_test.go b/whitespace_test.go
new file mode 100644
index 0000000..fdc1d09
--- /dev/null
+++ b/whitespace_test.go
@@ -0,0 +1,52 @@
+package lipgloss
+
+import (
+	"testing"
+	"time"
+)
+
+func TestWhitespaceRenderWithTab(t *testing.T) {
+	// This test verifies that rendering whitespace with tab characters
+	// doesn't cause an infinite loop (issue #108)
+	done := make(chan bool, 1)
+
+	go func() {
+		ws := newWhitespace(WithWhitespaceChars("\t"))
+		_ = ws.render(10)
+		done <- true
+	}()
+
+	select {
+	case <-done:
+		// Success - render completed
+	case <-time.After(2 * time.Second):
+		t.Fatal("whitespace.render() with tab character caused infinite loop")
+	}
+}
+
+func TestWhitespaceRenderWithZeroWidthChar(t *testing.T) {
+	// Test with zero-width joiner (another zero-width character)
+	done := make(chan bool, 1)
+
+	go func() {
+		ws := newWhitespace(WithWhitespaceChars("\u200d")) // zero-width joiner
+		_ = ws.render(5)
+		done <- true
+	}()
+
+	select {
+	case <-done:
+		// Success
+	case <-time.After(2 * time.Second):
+		t.Fatal("whitespace.render() with zero-width character caused infinite loop")
+	}
+}
+
+func TestWhitespaceRenderNormal(t *testing.T) {
+	// Verify normal behavior still works
+	ws := newWhitespace(WithWhitespaceChars("*"))
+	result := ws.render(5)
+	if len(result) != 5 {
+		t.Errorf("expected 5 characters, got %d", len(result))
+	}
+}