chore: make deps

vendor/github.com/clipperhouse/displaywidth/width.go

@@ -0,0 +1,210 @@
+package displaywidth
+
+import (
+	"unicode/utf8"
+
+	"github.com/clipperhouse/stringish"
+	"github.com/clipperhouse/uax29/v2/graphemes"
+)
+
+// String calculates the display width of a string,
+// by iterating over grapheme clusters in the string
+// and summing their widths.
+func String(s string) int {
+	return DefaultOptions.String(s)
+}
+
+// Bytes calculates the display width of a []byte,
+// by iterating over grapheme clusters in the byte slice
+// and summing their widths.
+func Bytes(s []byte) int {
+	return DefaultOptions.Bytes(s)
+}
+
+// Rune calculates the display width of a rune. You
+// should almost certainly use [String] or [Bytes] for
+// most purposes.
+//
+// The smallest unit of display width is a grapheme
+// cluster, not a rune. Iterating over runes to measure
+// width is incorrect in most cases.
+func Rune(r rune) int {
+	return DefaultOptions.Rune(r)
+}
+
+// Options allows you to specify the treatment of ambiguous East Asian
+// characters. When EastAsianWidth is false (default), ambiguous East Asian
+// characters are treated as width 1. When EastAsianWidth is true, ambiguous
+// East Asian characters are treated as width 2.
+type Options struct {
+	EastAsianWidth bool
+}
+
+// DefaultOptions is the default options for the display width
+// calculation, which is EastAsianWidth: false.
+var DefaultOptions = Options{EastAsianWidth: false}
+
+// String calculates the display width of a string,
+// for the given options, by iterating over grapheme clusters
+// and summing their widths.
+func (options Options) String(s string) int {
+	if len(s) == 0 {
+		return 0
+	}
+
+	total := 0
+	g := graphemes.FromString(s)
+	for g.Next() {
+		props := lookupProperties(g.Value())
+		total += props.width(options)
+	}
+	return total
+}
+
+// Bytes calculates the display width of a []byte,
+// for the given options, by iterating over grapheme
+// clusters in the byte slice and summing their widths.
+func (options Options) Bytes(s []byte) int {
+	if len(s) == 0 {
+		return 0
+	}
+
+	total := 0
+	g := graphemes.FromBytes(s)
+	for g.Next() {
+		props := lookupProperties(g.Value())
+		total += props.width(options)
+	}
+	return total
+}
+
+// Rune calculates the display width of a rune,
+// for the given options.
+//
+// The smallest unit of display width is a grapheme
+// cluster, not a rune. Iterating over runes to measure
+// width is incorrect in most cases.
+func (options Options) Rune(r rune) int {
+	// Fast path for ASCII
+	if r < utf8.RuneSelf {
+		if isASCIIControl(byte(r)) {
+			// Control (0x00-0x1F) and DEL (0x7F)
+			return 0
+		}
+		// ASCII printable (0x20-0x7E)
+		return 1
+	}
+
+	// Surrogates (U+D800-U+DFFF) are invalid UTF-8 and have zero width
+	// Other packages might turn them into the replacement character (U+FFFD)
+	// in which case, we won't see it.
+	if r >= 0xD800 && r <= 0xDFFF {
+		return 0
+	}
+
+	// Stack-allocated to avoid heap allocation
+	var buf [4]byte // UTF-8 is at most 4 bytes
+	n := utf8.EncodeRune(buf[:], r)
+	// Skip the grapheme iterator and directly lookup properties
+	props := lookupProperties(buf[:n])
+	return props.width(options)
+}
+
+func isASCIIControl(b byte) bool {
+	return b < 0x20 || b == 0x7F
+}
+
+// isRIPrefix checks if the slice matches the Regional Indicator prefix
+// (F0 9F 87). It assumes len(s) >= 3.
+func isRIPrefix[T stringish.Interface](s T) bool {
+	return s[0] == 0xF0 && s[1] == 0x9F && s[2] == 0x87
+}
+
+// isVS16 checks if the slice matches VS16 (U+FE0F) UTF-8 encoding
+// (EF B8 8F). It assumes len(s) >= 3.
+func isVS16[T stringish.Interface](s T) bool {
+	return s[0] == 0xEF && s[1] == 0xB8 && s[2] == 0x8F
+}
+
+// lookupProperties returns the properties for the first character in a string
+func lookupProperties[T stringish.Interface](s T) property {
+	l := len(s)
+
+	if l == 0 {
+		return 0
+	}
+
+	b := s[0]
+	if isASCIIControl(b) {
+		return _Zero_Width
+	}
+
+	if b < utf8.RuneSelf {
+		// Check for variation selector after ASCII (e.g., keycap sequences like 1️⃣)
+		if l >= 4 {
+			// Subslice may help eliminate bounds checks
+			vs := s[1:4]
+			if isVS16(vs) {
+				// VS16 requests emoji presentation (width 2)
+				return _Emoji
+			}
+			// VS15 (0x8E) requests text presentation but does not affect width,
+			// in my reading of Unicode TR51. Falls through to _Default.
+		}
+		return _Default
+	}
+
+	// Regional indicator pair (flag)
+	if l >= 8 {
+		// Subslice may help eliminate bounds checks
+		ri := s[:8]
+		if isRIPrefix(ri[0:3]) {
+			b3 := ri[3]
+			if b3 >= 0xA6 && b3 <= 0xBF && isRIPrefix(ri[4:7]) {
+				b7 := ri[7]
+				if b7 >= 0xA6 && b7 <= 0xBF {
+					return _Emoji
+				}
+			}
+		}
+	}
+
+	props, size := lookup(s)
+	p := property(props)
+
+	// Variation Selectors
+	if size > 0 && l >= size+3 {
+		// Subslice may help eliminate bounds checks
+		vs := s[size : size+3]
+		if isVS16(vs) {
+			// VS16 requests emoji presentation (width 2)
+			return _Emoji
+		}
+		// VS15 (0x8E) requests text presentation but does not affect width,
+		// in my reading of Unicode TR51. Falls through to return the base
+		// character's property (p).
+	}
+
+	return p
+}
+
+const _Default property = 0
+
+// a jump table of sorts, instead of a switch
+var widthTable = [5]int{
+	_Default:              1,
+	_Zero_Width:           0,
+	_East_Asian_Wide:      2,
+	_East_Asian_Ambiguous: 1,
+	_Emoji:                2,
+}
+
+// width determines the display width of a character based on its properties
+// and configuration options
+func (p property) width(options Options) int {
+	if options.EastAsianWidth && p == _East_Asian_Ambiguous {
+		return 2
+	}
+
+	return widthTable[p]
+}