cmd/horsebot: move to here

cmd/horsebot/autocomplete/autocomplete.go

@@ -0,0 +1,56 @@
+package autocomplete
+
+import (
+	"bytes"
+	"cmp"
+	"slices"
+	"sync"
+
+	"github.com/junegunn/fzf/src/algo"
+	"github.com/junegunn/fzf/src/util"
+)
+
+// Set is an autocomplete set.
+type Set[V any] struct {
+	keys []util.Chars
+	vals []V
+}
+
+// Add associates a value with a key in the autocomplete set.
+// The behavior is undefined if the key already has a value.
+func (s *Set[V]) Add(key string, val V) {
+	k := util.ToChars([]byte(key))
+	i, _ := slices.BinarySearchFunc(s.keys, k, func(a, b util.Chars) int {
+		return bytes.Compare(a.Bytes(), b.Bytes())
+	})
+	s.keys = slices.Insert(s.keys, i, k)
+	s.vals = slices.Insert(s.vals, i, val)
+}
+
+// Find appends to r all values in the set with keys that key matches.
+func (s *Set[V]) Find(r []V, key string) []V {
+	initFzf()
+	var (
+		p = []rune(key)
+
+		got  []V
+		t    []algo.Result
+		slab util.Slab
+	)
+	for i := range s.keys {
+		res, _ := algo.FuzzyMatchV2(false, true, true, &s.keys[i], p, false, &slab)
+		if res.Score <= 0 {
+			continue
+		}
+		j, _ := slices.BinarySearchFunc(t, res, func(a, b algo.Result) int { return -cmp.Compare(a.Score, b.Score) })
+		// Insert after all other matches with the same score for stability.
+		for j < len(t) && t[j].Score == res.Score {
+			j++
+		}
+		t = slices.Insert(t, j, res)
+		got = slices.Insert(got, j, s.vals[i])
+	}
+	return append(r, got...)
+}
+
+var initFzf = sync.OnceFunc(func() { algo.Init("default") })

cmd/horsebot/autocomplete/autocomplete_test.go

@@ -0,0 +1,70 @@
+package autocomplete_test
+
+import (
+	"slices"
+	"testing"
+
+	"git.sunturtle.xyz/zephyr/horse/cmd/horsebot/autocomplete"
+)
+
+func these(s ...string) []string { return s }
+
+func TestAutocomplete(t *testing.T) {
+	cases := []struct {
+		name   string
+		add    []string
+		search string
+		want   []string
+	}{
+		{
+			name:   "empty",
+			add:    nil,
+			search: "",
+			want:   nil,
+		},
+		{
+			name:   "exact",
+			add:    these("bocchi"),
+			search: "bocchi",
+			want:   these("bocchi"),
+		},
+		{
+			name:   "extra",
+			add:    these("bocchi", "ryo", "nijika", "kita"),
+			search: "bocchi",
+			want:   these("bocchi"),
+		},
+		{
+			name:   "short",
+			add:    these("bocchi", "ryo", "nijika", "kita"),
+			search: "o",
+			want:   these("bocchi", "ryo"),
+		},
+		{
+			name:   "unrelated",
+			add:    these("bocchi", "ryo", "nijika", "kita"),
+			search: "x",
+			want:   nil,
+		},
+		{
+			name:   "map",
+			add:    these("Corazón ☆ Ardiente"),
+			search: "corazo",
+			want:   these("Corazón ☆ Ardiente"),
+		},
+	}
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			var set autocomplete.Set[string]
+			for _, s := range c.add {
+				set.Add(s, s)
+			}
+			got := set.Find(nil, c.search)
+			slices.Sort(c.want)
+			slices.Sort(got)
+			if !slices.Equal(c.want, got) {
+				t.Errorf("wrong results: want %q, got %q", c.want, got)
+			}
+		})
+	}
+}