chore: make deps

vendor/github.com/clipperhouse/displaywidth/.gitignore

@@ -0,0 +1 @@
+.DS_Store

vendor/github.com/clipperhouse/displaywidth/AGENTS.md

@@ -0,0 +1,37 @@
+The goals and overview of this package can be found in the README.md file,
+start by reading that.
+
+The goal of this package is to determine the display (column) width of a
+string, UTF-8 bytes, or runes, as would happen in a monospace font, especially
+in a terminal.
+
+When troubleshooting, write Go unit tests instead of executing debug scripts.
+The tests can return whatever logs or output you need. If those tests are
+only for temporary troubleshooting, clean up the tests after the debugging is
+done.
+
+(Separate executable debugging scripts are messy, tend to have conflicting
+dependencies and are hard to cleanup.)
+
+If you make changes to the trie generation in internal/gen, it can be invoked
+by running `go generate` from the top package directory.
+
+## Pull Requests and branches
+
+For PRs (pull requests), you can use the gh CLI tool to retrieve details,
+or post comments. Then, compare the current branch with main. Reviewing a PR
+and reviewing a branch are about the same, but the PR may add context.
+
+Look for bugs. Think like GitHub Copilot or Cursor BugBot.
+
+Offer to post a brief summary of the review to the PR, via the gh CLI tool.
+
+## Comparisons to go-runewidth
+
+We originally attempted to make this package compatible with go-runewidth.
+However, we found that there were too many differences in the handling of
+certain characters and properties.
+
+We believe, preliminarily, that our choices are more correct and complete,
+by using more complete categories such as Unicode Cf (format) for zero-width
+and Mn (Nonspacing_Mark) for combining marks.

vendor/github.com/clipperhouse/displaywidth/CHANGELOG.md

@@ -0,0 +1,49 @@
+# Changelog
+
+## [0.5.0]
+
+[Compare](https://github.com/clipperhouse/displaywidth/compare/v0.4.1...v0.5.0)
+
+### Added
+- Unicode 16 support
+- Improved emoji presentation handling per Unicode TR51
+
+### Changed
+- Corrected VS15 (U+FE0E) handling: now preserves base character width (no-op) per Unicode TR51
+- Performance optimizations: reduced property lookups
+
+### Fixed
+- VS15 variation selector now correctly preserves base character width instead of forcing width 1
+
+## [0.4.1]
+
+[Compare](https://github.com/clipperhouse/displaywidth/compare/v0.4.0...v0.4.1)
+
+### Changed
+- Updated uax29 dependency
+- Improved flag handling
+
+## [0.4.0]
+
+[Compare](https://github.com/clipperhouse/displaywidth/compare/v0.3.1...v0.4.0)
+
+### Added
+- Support for variation selectors (VS15, VS16) and regional indicator pairs (flags)
+
+## [0.3.1]
+
+[Compare](https://github.com/clipperhouse/displaywidth/compare/v0.3.0...v0.3.1)
+
+### Added
+- Fuzz testing support
+
+### Changed
+- Updated stringish dependency
+
+## [0.3.0]
+
+[Compare](https://github.com/clipperhouse/displaywidth/compare/v0.2.0...v0.3.0)
+
+### Changed
+- Dropped compatibility with go-runewidth
+- Trie implementation cleanup

vendor/github.com/clipperhouse/displaywidth/LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2025 Matt Sherman
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

vendor/github.com/clipperhouse/displaywidth/README.md

@@ -0,0 +1,123 @@
+# displaywidth
+
+A high-performance Go package for measuring the monospace display width of strings, UTF-8 bytes, and runes.
+
+[![Documentation](https://pkg.go.dev/badge/github.com/clipperhouse/displaywidth.svg)](https://pkg.go.dev/github.com/clipperhouse/displaywidth)
+[![Test](https://github.com/clipperhouse/displaywidth/actions/workflows/gotest.yml/badge.svg)](https://github.com/clipperhouse/displaywidth/actions/workflows/gotest.yml)
+[![Fuzz](https://github.com/clipperhouse/displaywidth/actions/workflows/gofuzz.yml/badge.svg)](https://github.com/clipperhouse/displaywidth/actions/workflows/gofuzz.yml)
+
+## Install
+```bash
+go get github.com/clipperhouse/displaywidth
+```
+
+## Usage
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/clipperhouse/displaywidth"
+)
+
+func main() {
+    width := displaywidth.String("Hello, 世界!")
+    fmt.Println(width)
+
+    width = displaywidth.Bytes([]byte("🌍"))
+    fmt.Println(width)
+
+    width = displaywidth.Rune('🌍')
+    fmt.Println(width)
+}
+```
+
+For most purposes, you should use the `String` or `Bytes` methods.
+
+
+### Options
+
+You can specify East Asian Width settings. When false (default),
+[East Asian Ambiguous characters](https://www.unicode.org/reports/tr11/#Ambiguous)
+are treated as width 1. When true, East Asian Ambiguous characters are treated
+as width 2.
+
+```go
+myOptions := displaywidth.Options{
+    EastAsianWidth: true,
+}
+
+width := myOptions.String("Hello, 世界!")
+fmt.Println(width)
+```
+
+## Technical details
+
+This package implements the Unicode East Asian Width standard
+([UAX #11](https://www.unicode.org/reports/tr11/)), and handles
+[version selectors](https://en.wikipedia.org/wiki/Variation_Selectors_(Unicode_block)),
+and [regional indicator pairs](https://en.wikipedia.org/wiki/Regional_indicator_symbol)
+(flags). We implement [Unicode TR51](https://unicode.org/reports/tr51/).
+
+`clipperhouse/displaywidth`, `mattn/go-runewidth`, and `rivo/uniseg` will
+give the same outputs for most real-world text. See extensive details in the
+[compatibility analysis](comparison/COMPATIBILITY_ANALYSIS.md).
+
+If you wish to investigate the core logic, see the `lookupProperties` and `width`
+functions in [width.go](width.go#L135). The essential trie generation logic is in
+`buildPropertyBitmap` in [unicode.go](internal/gen/unicode.go#L317).
+
+I (@clipperhouse) am keeping an eye on [emerging standards and test suites](https://www.jeffquast.com/post/state-of-terminal-emulation-2025/).
+
+## Prior Art
+
+[mattn/go-runewidth](https://github.com/mattn/go-runewidth)
+
+[rivo/uniseg](https://github.com/rivo/uniseg)
+
+[x/text/width](https://pkg.go.dev/golang.org/x/text/width)
+
+[x/text/internal/triegen](https://pkg.go.dev/golang.org/x/text/internal/triegen)
+
+## Benchmarks
+
+```bash
+cd comparison
+go test -bench=. -benchmem
+```
+
+```
+goos: darwin
+goarch: arm64
+pkg: github.com/clipperhouse/displaywidth/comparison
+cpu: Apple M2
+
+BenchmarkString_Mixed/clipperhouse/displaywidth-8         10929 ns/op	    154.36 MB/s	      0 B/op     0 allocs/op
+BenchmarkString_Mixed/mattn/go-runewidth-8                14540 ns/op	    116.02 MB/s	      0 B/op     0 allocs/op
+BenchmarkString_Mixed/rivo/uniseg-8                       19751 ns/op	     85.41 MB/s	      0 B/op     0 allocs/op
+
+BenchmarkString_EastAsian/clipperhouse/displaywidth-8     10885 ns/op	    154.98 MB/s	      0 B/op     0 allocs/op
+BenchmarkString_EastAsian/mattn/go-runewidth-8            23969 ns/op	     70.38 MB/s	      0 B/op     0 allocs/op
+BenchmarkString_EastAsian/rivo/uniseg-8                   19852 ns/op	     84.98 MB/s	      0 B/op     0 allocs/op
+
+BenchmarkString_ASCII/clipperhouse/displaywidth-8          1103 ns/op	    116.01 MB/s	      0 B/op     0 allocs/op
+BenchmarkString_ASCII/mattn/go-runewidth-8                 1166 ns/op	    109.79 MB/s	      0 B/op     0 allocs/op
+BenchmarkString_ASCII/rivo/uniseg-8                        1584 ns/op	     80.83 MB/s	      0 B/op     0 allocs/op
+
+BenchmarkString_Emoji/clipperhouse/displaywidth-8          3108 ns/op	    232.93 MB/s	      0 B/op     0 allocs/op
+BenchmarkString_Emoji/mattn/go-runewidth-8                 4802 ns/op	    150.76 MB/s	      0 B/op     0 allocs/op
+BenchmarkString_Emoji/rivo/uniseg-8                        6607 ns/op	    109.58 MB/s	      0 B/op     0 allocs/op
+
+BenchmarkRune_Mixed/clipperhouse/displaywidth-8            3456 ns/op	    488.20 MB/s	      0 B/op     0 allocs/op
+BenchmarkRune_Mixed/mattn/go-runewidth-8                   5400 ns/op	    312.39 MB/s	      0 B/op     0 allocs/op
+
+BenchmarkRune_EastAsian/clipperhouse/displaywidth-8        3475 ns/op	    485.41 MB/s	      0 B/op     0 allocs/op
+BenchmarkRune_EastAsian/mattn/go-runewidth-8              15701 ns/op	    107.44 MB/s	      0 B/op     0 allocs/op
+
+BenchmarkRune_ASCII/clipperhouse/displaywidth-8             257.0 ns/op	    498.13 MB/s	      0 B/op     0 allocs/op
+BenchmarkRune_ASCII/mattn/go-runewidth-8                    266.4 ns/op	    480.50 MB/s	      0 B/op     0 allocs/op
+
+BenchmarkRune_Emoji/clipperhouse/displaywidth-8            1384 ns/op	    523.02 MB/s	      0 B/op     0 allocs/op
+BenchmarkRune_Emoji/mattn/go-runewidth-8                   2273 ns/op	    318.45 MB/s	      0 B/op     0 allocs/op
+```

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

@@ -0,0 +1,3 @@
+package displaywidth
+
+//go:generate go run -C internal/gen .

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]
+}

vendor/github.com/clipperhouse/stringish/.gitignore

@@ -0,0 +1,2 @@
+.DS_Store
+*.test

vendor/github.com/clipperhouse/stringish/LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2025 Matt Sherman
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

vendor/github.com/clipperhouse/stringish/README.md

@@ -0,0 +1,64 @@
+# stringish
+
+A small Go module that provides a generic type constraint for “string-like”
+data, and a utf8 package that works with both strings and byte slices
+without conversions.
+
+```go
+type Interface interface {
+	~[]byte | ~string
+}
+```
+
+[![Go Reference](https://pkg.go.dev/badge/github.com/clipperhouse/stringish/utf8.svg)](https://pkg.go.dev/github.com/clipperhouse/stringish/utf8)
+[![Test Status](https://github.com/clipperhouse/stringish/actions/workflows/gotest.yml/badge.svg)](https://github.com/clipperhouse/stringish/actions/workflows/gotest.yml)
+
+## Install
+
+```
+go get github.com/clipperhouse/stringish
+```
+
+## Examples
+
+```go
+import (
+    "github.com/clipperhouse/stringish"
+    "github.com/clipperhouse/stringish/utf8"
+)
+
+s := "Hello, 世界"
+r, size := utf8.DecodeRune(s)   // not DecodeRuneInString 🎉
+
+b := []byte("Hello, 世界")
+r, size = utf8.DecodeRune(b)    // same API!
+
+func MyFoo[T stringish.Interface](s T) T {
+    // pass a string or a []byte
+    // iterate, slice, transform, whatever
+}
+```
+
+## Motivation
+
+Sometimes we want APIs to accept `string` or `[]byte` without having to convert
+between those types. That conversion usually allocates!
+
+By implementing with `stringish.Interface`, we can have a single API, and
+single implementation for both types: one `Foo` instead of `Foo` and
+`FooString`.
+
+We have converted the
+[`unicode/utf8` package](https://github.com/clipperhouse/stringish/blob/main/utf8/utf8.go)
+as an example -- note the absence of`*InString` funcs. We might look at `x/text`
+next.
+
+## Used by
+
+- clipperhouse/uax29: [stringish trie](https://github.com/clipperhouse/uax29/blob/master/graphemes/trie.go#L27), [stringish iterator](https://github.com/clipperhouse/uax29/blob/master/internal/iterators/iterator.go#L9), [stringish SplitFunc](https://github.com/clipperhouse/uax29/blob/master/graphemes/splitfunc.go#L21)
+
+- [clipperhouse/displaywidth](https://github.com/clipperhouse/displaywidth)
+
+## Prior discussion
+
+- [Consideration of similar by the Go team](https://github.com/golang/go/issues/48643)

vendor/github.com/clipperhouse/stringish/interface.go

@@ -0,0 +1,5 @@
+package stringish
+
+type Interface interface {
+	~[]byte | ~string
+}

vendor/github.com/clipperhouse/uax29/v2/graphemes/README.md

@@ -1,5 +1,9 @@
 An implementation of grapheme cluster boundaries from [Unicode text segmentation](https://unicode.org/reports/tr29/#Grapheme_Cluster_Boundaries) (UAX 29), for Unicode version 15.0.0.
 
+[![Documentation](https://pkg.go.dev/badge/github.com/clipperhouse/uax29/v2/graphemes.svg)](https://pkg.go.dev/github.com/clipperhouse/uax29/v2/graphemes)
+![Tests](https://github.com/clipperhouse/uax29/actions/workflows/gotest.yml/badge.svg)
+![Fuzz](https://github.com/clipperhouse/uax29/actions/workflows/gofuzz.yml/badge.svg)
+
 ## Quick start
 
 ```
@@ -18,15 +22,14 @@ for tokens.Next() {                     // Next() returns true until end of data
 }
 ```
 
-[![Documentation](https://pkg.go.dev/badge/github.com/clipperhouse/uax29/v2/graphemes.svg)](https://pkg.go.dev/github.com/clipperhouse/uax29/v2/graphemes)
-
 _A grapheme is a “single visible character”, which might be a simple as a single letter, or a complex emoji that consists of several Unicode code points._
 
 ## Conformance
 
-We use the Unicode [test suite](https://unicode.org/reports/tr41/tr41-26.html#Tests29). Status:
+We use the Unicode [test suite](https://unicode.org/reports/tr41/tr41-26.html#Tests29).
 
-![Go](https://github.com/clipperhouse/uax29/actions/workflows/gotest.yml/badge.svg)
+![Tests](https://github.com/clipperhouse/uax29/actions/workflows/gotest.yml/badge.svg)
+![Fuzz](https://github.com/clipperhouse/uax29/actions/workflows/gofuzz.yml/badge.svg)
 
 ## APIs
 
@@ -71,9 +74,18 @@ for tokens.Next() {                     // Next() returns true until end of data
 }
 ```
 
-### Performance
+### Benchmarks
 
-On a Mac M2 laptop, we see around 200MB/s, or around 100 million graphemes per second. You should see ~constant memory, and no allocations.
+On a Mac M2 laptop, we see around 200MB/s, or around 100 million graphemes per second, and no allocations.
+
+```
+goos: darwin
+goarch: arm64
+pkg: github.com/clipperhouse/uax29/graphemes/comparative
+cpu: Apple M2
+BenchmarkGraphemes/clipperhouse/uax29-8    	    173805 ns/op	 201.16 MB/s      0 B/op	   0 allocs/op
+BenchmarkGraphemes/rivo/uniseg-8           	   2045128 ns/op	  17.10 MB/s      0 B/op	   0 allocs/op
+```
 
 ### Invalid inputs
 

vendor/github.com/clipperhouse/uax29/v2/graphemes/iterator.go

@@ -1,8 +1,11 @@
 package graphemes
 
-import "github.com/clipperhouse/uax29/v2/internal/iterators"
+import (
+	"github.com/clipperhouse/stringish"
+	"github.com/clipperhouse/uax29/v2/internal/iterators"
+)
 
-type Iterator[T iterators.Stringish] struct {
+type Iterator[T stringish.Interface] struct {
 	*iterators.Iterator[T]
 }
 

vendor/github.com/clipperhouse/uax29/v2/graphemes/splitfunc.go

@@ -3,7 +3,7 @@ package graphemes
 import (
 	"bufio"
 
-	"github.com/clipperhouse/uax29/v2/internal/iterators"
+	"github.com/clipperhouse/stringish"
 )
 
 // is determines if lookup intersects propert(ies)
@@ -18,7 +18,7 @@ const _Ignore = _Extend
 // See https://unicode.org/reports/tr29/#Grapheme_Cluster_Boundaries.
 var SplitFunc bufio.SplitFunc = splitFunc[[]byte]
 
-func splitFunc[T iterators.Stringish](data T, atEOF bool) (advance int, token T, err error) {
+func splitFunc[T stringish.Interface](data T, atEOF bool) (advance int, token T, err error) {
 	var empty T
 	if len(data) == 0 {
 		return 0, empty, nil

vendor/github.com/clipperhouse/uax29/v2/graphemes/trie.go

@@ -1,10 +1,10 @@
 package graphemes
 
+import "github.com/clipperhouse/stringish"
+
 // generated by github.com/clipperhouse/uax29/v2
 // from https://www.unicode.org/Public/15.0.0/ucd/auxiliary/GraphemeBreakProperty.txt
 
-import "github.com/clipperhouse/uax29/v2/internal/iterators"
-
 type property uint16
 
 const (
@@ -27,7 +27,7 @@ const (
 // lookup returns the trie value for the first UTF-8 encoding in s and
 // the width in bytes of this encoding. The size will be 0 if s does not
 // hold enough bytes to complete the encoding. len(s) must be greater than 0.
-func lookup[T iterators.Stringish](s T) (v property, sz int) {
+func lookup[T stringish.Interface](s T) (v property, sz int) {
 	c0 := s[0]
 	switch {
 	case c0 < 0x80: // is ASCII

vendor/github.com/clipperhouse/uax29/v2/internal/iterators/iterator.go

@@ -1,14 +1,12 @@
 package iterators
 
-type Stringish interface {
-	[]byte | string
-}
+import "github.com/clipperhouse/stringish"
 
-type SplitFunc[T Stringish] func(T, bool) (int, T, error)
+type SplitFunc[T stringish.Interface] func(T, bool) (int, T, error)
 
 // Iterator is a generic iterator for words that are either []byte or string.
 // Iterate while Next() is true, and access the word via Value().
-type Iterator[T Stringish] struct {
+type Iterator[T stringish.Interface] struct {
 	split SplitFunc[T]
 	data  T
 	start int
@@ -16,7 +14,7 @@ type Iterator[T Stringish] struct {
 }
 
 // New creates a new Iterator for the given data and SplitFunc.
-func New[T Stringish](split SplitFunc[T], data T) *Iterator[T] {
+func New[T stringish.Interface](split SplitFunc[T], data T) *Iterator[T] {
 	return &Iterator[T]{
 		split: split,
 		data:  data,
@@ -83,3 +81,20 @@ func (iter *Iterator[T]) Reset() {
 	iter.start = 0
 	iter.pos = 0
 }
+
+func (iter *Iterator[T]) First() T {
+	if len(iter.data) == 0 {
+		return iter.data
+	}
+	advance, _, err := iter.split(iter.data, true)
+	if err != nil {
+		panic(err)
+	}
+	if advance <= 0 {
+		panic("SplitFunc returned a zero or negative advance")
+	}
+	if advance > len(iter.data) {
+		panic("SplitFunc advanced beyond the end of the data")
+	}
+	return iter.data[:advance]
+}