From 7029a35df9b4ba2cc35fcfc6efa68d91c4fc10e8 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Fri, 6 Jun 2025 13:28:58 +0530
Subject: [PATCH] Port subseq tests to fzf

---
 tools/fzf/algo_test.go | 100 +++++++++++++++++++++++++++++++++++++++++
 tools/fzf/types.go     |  30 ++++++-------
 2 files changed, 115 insertions(+), 15 deletions(-)

diff --git a/tools/fzf/algo_test.go b/tools/fzf/algo_test.go
index a5a5a2f7a..330eb2769 100644
--- a/tools/fzf/algo_test.go
+++ b/tools/fzf/algo_test.go
@@ -1,9 +1,16 @@
 package fzf
 
 import (
+	"cmp"
 	"fmt"
 	"sort"
+	"strconv"
+	"strings"
 	"testing"
+
+	gcmp "github.com/google/go-cmp/cmp"
+
+	"github.com/kovidgoyal/kitty/tools/utils"
 )
 
 var _ = fmt.Print
@@ -87,4 +94,97 @@ func TestFZFAlgo(t *testing.T) {
 		assertMatch(t, fn, "Foo Bar Baz", "fbb", -1, -1, 0)
 		assertMatch(t, fn, "fooBarbaz", "fooBarbazz", -1, -1, 0)
 	}
+
+	var positions [][]int
+	sort_by_score := false
+	fn.Case_sensitive = false
+
+	simple := func(items, query string, expected ...string) {
+		ilist := utils.Splitlines(items)
+		matches, err := fn.Score(ilist, query)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if sort_by_score {
+			slist := make([]int, len(matches))
+			for i := range len(slist) {
+				slist[i] = i
+			}
+			utils.StableSort(slist, func(a, b int) int {
+				return cmp.Compare(matches[b].Score, matches[a].Score)
+			})
+			nlist, nmatches := make([]string, len(ilist)), make([]Result, len(matches))
+			for i, j := range slist {
+				nlist[i] = ilist[j]
+				nmatches[i] = matches[j]
+			}
+			ilist = nlist
+			matches = nmatches
+		}
+		actual := make([]string, 0, len(matches))
+		actual_positions := make([][]int, 0, len(matches))
+		for i, m := range matches {
+			if m.Score > 0 {
+				sort.Ints(m.Positions)
+				actual = append(actual, ilist[i])
+				actual_positions = append(actual_positions, m.Positions)
+			}
+		}
+		if expected == nil {
+			expected = []string{}
+		}
+
+		if diff := gcmp.Diff(expected, actual); diff != "" {
+			t.Fatalf("Failed for items: %#v\nQuery: %#v\nMatches: %#v\n%s", ilist, query, matches, diff)
+		}
+		if positions != nil {
+			if diff := gcmp.Diff(positions, actual_positions); diff != "" {
+				t.Fatalf("Failed positions for items: %v\n%s", ilist, diff)
+			}
+			positions = nil
+		}
+	}
+	simple("test\nxyz", "te", "test")
+	simple("abc\nxyz", "ba")
+	simple("abc\n123", "abc", "abc")
+	simple("test\nxyz", "Te", "test")
+	simple("test\nxyz", "XY", "xyz")
+	simple("test\nXYZ", "xy", "XYZ")
+	simple("test\nXYZ", "mn")
+
+	positions = [][]int{{0, 2}, {0, 1}}
+	simple("abc\nac", "ac", "abc", "ac")
+	positions = [][]int{{0}}
+	simple("abc\nv", "a", "abc")
+	positions = [][]int{{1, 3}}
+	simple("汉a字b\nxyz", "ab", "汉a字b")
+
+	sort_by_score = true
+	// Match at start
+	simple("archer\nelementary", "e", "elementary", "archer")
+	// Match at level factor
+	simple("xxxy\nxx/y", "y", "xx/y", "xxxy")
+	// CamelCase
+	simple("xxxy\nxxxY", "y", "xxxY", "xxxy")
+	// Distance
+	simple("abbc\nabc", "ac", "abc", "abbc")
+	// Extreme chars
+	simple("xxa\naxx", "a", "axx", "xxa")
+	// Highest score
+	positions = [][]int{{3}}
+	simple("xa/a", "a", "xa/a")
+
+	sort_by_score = false
+	items := make([]string, 256)
+
+	for i := range items {
+		items[i] = strconv.Itoa(i)
+	}
+	expected := make([]string, 0, len(items))
+	for _, x := range items {
+		if strings.ContainsRune(x, rune('2')) {
+			expected = append(expected, x)
+		}
+	}
+	simple(strings.Join(items, "\n"), "2", expected...)
 }
diff --git a/tools/fzf/types.go b/tools/fzf/types.go
index c9bae90f0..3e52d3c8c 100644
--- a/tools/fzf/types.go
+++ b/tools/fzf/types.go
@@ -20,25 +20,25 @@ type Chars struct {
 	runes []rune
 }
 
-const (
-	overflow64 uint64 = 0x8080808080808080
-	overflow32 uint32 = 0x80808080
-)
-
 func check_ascii(bytes []byte) (ascii_until int) {
+	slen := len(bytes)
+	// Process 8 bytes at a time
 	i := 0
-	for ; i <= len(bytes)-8; i += 8 {
-		if (overflow64 & *(*uint64)(unsafe.Pointer(&bytes[i]))) > 0 {
-			return i
+	for ; i+8 <= slen; i += 8 {
+		v := *(*uint64)(unsafe.Pointer(&bytes[i]))
+		// If any byte has its high bit set, v & 0x8080808080808080 != 0
+		if v&0x8080808080808080 != 0 {
+			// At least one non-ASCII byte in this chunk, find which
+			for j := range 8 {
+				if bytes[i+j]&utf8.RuneSelf != 0 {
+					return i + j
+				}
+			}
 		}
 	}
-	for ; i <= len(bytes)-4; i += 4 {
-		if (overflow32 & *(*uint32)(unsafe.Pointer(&bytes[i]))) > 0 {
-			return i
-		}
-	}
-	for ; i < len(bytes); i++ {
-		if bytes[i] >= utf8.RuneSelf {
+	// Handle remaining bytes
+	for ; i < slen; i++ {
+		if bytes[i] > 127 {
 			return i
 		}
 	}