Fix width calculation for unicode characters

util.go

@@ -15,7 +15,29 @@ import (
 	"github.com/mattn/go-runewidth"
 )
 
-var ansi = regexp.MustCompile("\033\\[(?:[0-9]{1,3}(?:;[0-9]{1,3})*)?[m|K]")
+var ansi = generateEscapeFilterRegex()
+
+// generateEscapeFilterRegex builds a regex to remove non-printing ANSI escape codes from strings so
+// that their display width can be determined accurately. The regex is complicated enough that it's
+// better to build it programmatically than to write it by hand.
+// Based on https://en.wikipedia.org/wiki/ANSI_escape_code#Fe_Escape_sequences
+func generateEscapeFilterRegex() *regexp.Regexp {
+	var regESC = "\x1b" // ASCII escape
+	var regBEL = "\x07" // ASCII bell
+
+	// String Terminator - ends ANSI sequences
+	var regST = "(" + regESC + "\\\\" + "|" + regBEL + ")"
+
+	// Control Sequence Introducer - usually color codes
+	// esc + [ + zero or more 0x30-0x3f + zero or more 0x20-0x2f and a single 0x40-0x7e
+	var regCSI = regESC + "\\[" + "[\x30-\x3f]*[\x20-\x2f]*[\x40-\x7e]"
+
+	// Operating System Command - hyperlinks
+	// esc + ] + any number of any chars + ST
+	var regOSC = regESC + "\\]" + ".*?" + regST
+
+	return regexp.MustCompile("(" + regCSI + "|" + regOSC + ")")
+}
 
 func DisplayWidth(str string) int {
 	return runewidth.StringWidth(ansi.ReplaceAllLiteralString(str, ""))

wrap.go

@@ -11,8 +11,6 @@ import (
 	"math"
 	"strings"
 	"unicode"
-
-	"github.com/mattn/go-runewidth"
 )
 
 const (
@@ -35,7 +33,7 @@ func WrapString(s string, lim int) ([]string, int) {
 	var lines []string
 	max := 0
 	for _, v := range words {
-		max = runewidth.StringWidth(v)
+		max = DisplayWidth(v)
 		if max > lim {
 			lim = max
 		}
@@ -87,7 +85,7 @@ func WrapWords(words []string, spc, lim, pen int) [][]string {
 	}
 	lengths := make([]int, n)
 	for i := 0; i < n; i++ {
-		lengths[i] = runewidth.StringWidth(words[i])
+		lengths[i] = DisplayWidth(words[i])
 	}
 	nbrk := make([]int, n)
 	cost := make([]int, n)