Normalize strings during filtering

This makes it easier to match characters with diacritics (i.e. you can type 'o'
and match an 'ö').

go.mod

@@ -24,4 +24,5 @@ require (
 	golang.org/x/crypto v0.0.0-20201016220609-9e8e0b390897
 	golang.org/x/net v0.0.0-20200813134508-3edf25e44fcc // indirect
 	golang.org/x/sys v0.0.0-20201020230747-6e5568b54d1a
+	golang.org/x/text v0.3.2
 )

ui/stash.go

@@ -9,6 +9,7 @@ import (
 	"sort"
 	"strings"
 	"time"
+	"unicode"
 
 	"github.com/charmbracelet/bubbles/paginator"
 	"github.com/charmbracelet/bubbles/spinner"
@@ -21,6 +22,8 @@ import (
 	"github.com/muesli/reflow/ansi"
 	te "github.com/muesli/termenv"
 	"github.com/sahilm/fuzzy"
+	"golang.org/x/text/transform"
+	"golang.org/x/text/unicode/norm"
 )
 
 const (
@@ -231,13 +234,16 @@ func (m *stashModel) getNotes() []*markdown {
 	targets := []string{}
 
 	for _, t := range m.markdowns {
-		note := ""
-		if t.markdownType == newsMarkdown {
-			note = "News: " + t.Note
-		} else {
+		note, err := normalize(t.Note)
+		if err != nil && debug {
+			log.Printf("error normalizing '%s': %v", t.Note, err)
 			note = t.Note
 		}
 
+		if t.markdownType == newsMarkdown {
+			note = "News: " + note
+		}
+
 		targets = append(targets, note)
 	}
 
@@ -1081,6 +1087,20 @@ func deleteStashedItem(cc *charm.Client, id int) tea.Cmd {
 
 // ETC
 
+// Normalize text to aid in the filtering process. in particular, we remove
+// diacritics.
+func normalize(in string) (string, error) {
+	t := transform.Chain(norm.NFD, transform.RemoveFunc(isMn), norm.NFC)
+	out, _, err := transform.String(t, in)
+	return out, err
+}
+
+// Returns whether a given rune is a nonspacing mark (Mn is the key for
+// nonspacing marks)
+func isMn(r rune) bool {
+	return unicode.Is(unicode.Mn, r)
+}
+
 // wrapMarkdowns wraps a *charm.Markdown with a *markdown in order to add some
 // extra metadata.
 func wrapMarkdowns(t markdownType, md []*charm.Markdown) (m []*markdown) {

ui/stashitem.go

@@ -2,6 +2,7 @@ package ui
 
 import (
 	"fmt"
+	"log"
 	"strings"
 
 	"github.com/charmbracelet/charm/ui/common"
@@ -122,13 +123,18 @@ func stashItemView(b *strings.Builder, m stashModel, index int, md *markdown) {
 func styleFilteredText(haystack, needles string, defaultStyle, matchedStyle termenv.Style) string {
 	b := strings.Builder{}
 
-	matches := fuzzy.Find(needles, []string{haystack})
+	normalizedHay, err := normalize(haystack)
+	if err != nil && debug {
+		log.Printf("error normalizing '%s': %v", haystack, err)
+	}
+
+	matches := fuzzy.Find(needles, []string{normalizedHay})
 	if len(matches) == 0 {
 		return defaultStyle.Styled(haystack)
 	}
 
 	m := matches[0] // only one match exists
-	for i, rune := range haystack {
+	for i, rune := range []rune(haystack) {
 		styled := false
 		for _, mi := range m.MatchedIndexes {
 			if i == mi {