fix(wcwidth): non-breaking space has width 1

wcwidth/wcwidth.go

@@ -15,13 +15,18 @@ import (
 	"golang.org/x/text/width"
 )
 
+const nbsp = 0xA0
+
 // RuneWidth returns fixed-width width of rune.
 // https://en.wikipedia.org/wiki/Halfwidth_and_fullwidth_forms#In_Unicode
 func RuneWidth(r rune) int {
 	// No width for categories Me (Mark, enclosing), Mn (Mark, non-spacing), and
 	// Cf (Other, format). We treat Control characters (class Cc) as zero width
 	// instead of -1.
 	if r == 0 || !unicode.IsPrint(r) || unicode.In(r, unicode.Me, unicode.Mn, unicode.Cf) {
+		if r == nbsp { // Special case: non-breaking space has width 1
+			return 1
+		}
 		return 0
 	}
 	k := width.LookupRune(r)

wcwidth/wcwidth_test.go

@@ -89,7 +89,7 @@ var runewidthtests = []struct {
 	{'\u0488', 0}, // Combining Cyrillic Hundred Thousands Sign
 	{'\u00ad', 0}, // Soft hyphen
 	{0, 0},        // Special case, width of null rune is zero
-	{'\u00a0', 0},
+	{'\u00a0', 1}, // non-breaking space
 }
 
 func BenchmarkRuneWidth(b *testing.B) {