Parse ignore files without the scanner line limit

gitignore.go

@@ -1,7 +1,6 @@
 package gitignore
 
 import (
-	"bufio"
 	"bytes"
 	"io/fs"
 	"os"
@@ -432,11 +431,13 @@ func matchPattern(p *pattern, pathSegs []string, isDir bool) bool {
 }
 
 func (m *Matcher) addPatterns(data []byte, dir, source string) {
-	scanner := bufio.NewScanner(bytes.NewReader(data))
 	lineNum := 0
-	for scanner.Scan() {
+	for len(data) > 0 {
+		var raw []byte
+		raw, data, _ = bytes.Cut(data, []byte{'\n'})
+		raw = bytes.TrimSuffix(raw, []byte{'\r'})
 		lineNum++
-		line := trimTrailingSpaces(scanner.Text())
+		line := trimTrailingSpaces(string(raw))
 		if line == "" || line[0] == '#' {
 			continue
 		}

long_lines_test.go

@@ -0,0 +1,73 @@
+package gitignore_test
+
+import (
+	"fmt"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"github.com/git-pkgs/gitignore"
+)
+
+func TestLongIgnoreLines(t *testing.T) {
+	requireGit(t)
+	isolateGitEnv(t)
+	for _, size := range []int{65535, 65536, 70000} {
+		for _, prefix := range []string{"", "#"} {
+			for _, newline := range []string{"\n", "\r\n"} {
+				t.Run(fmt.Sprintf("Size%d/Comment%t/CRLF%t", size, prefix != "", newline == "\r\n"), func(t *testing.T) {
+					checkLongIgnoreLines(t, size, prefix, newline)
+				})
+			}
+		}
+	}
+}
+
+func checkLongIgnoreLines(t *testing.T, size int, prefix, newline string) {
+	t.Helper()
+	long := strings.Repeat("a", size)
+	data := []byte(prefix + long + newline + newline + "*.log" + newline + "[" + newline + "!keep.log")
+	paths := parsePathList("app.log\nkeep.log\nmain.go\n")
+	root := buildRepo(t, string(data), paths)
+	want := gitCheckIgnore(t, root, paths)
+	programmatic := gitignore.New("")
+	programmatic.AddPatterns(data, "")
+	file := gitignore.New("")
+	source := filepath.Join(root, ".gitignore")
+	file.AddFromFile(source, "")
+	for _, m := range []*gitignore.Matcher{programmatic, file, gitignore.New(root)} {
+		for _, p := range paths {
+			if got := m.Match(p.query()); got != want[p.rel] {
+				t.Errorf("Match(%q) = %v, Git = %v", p.rel, got, want[p.rel])
+			}
+		}
+		if got := m.Match(long); got != (prefix == "") {
+			t.Errorf("long pattern match = %v", got)
+		}
+		expectedSource := source
+		if m == programmatic {
+			expectedSource = ""
+		}
+		detail := m.MatchDetail("app.log")
+		if detail.Line != 3 || detail.Source != expectedSource {
+			t.Errorf("MatchDetail = %+v", detail)
+		}
+		errs := m.Errors()
+		if len(errs) != 1 || errs[0].Line != 4 || errs[0].Source != expectedSource {
+			t.Errorf("Errors = %v", errs)
+		}
+	}
+}
+
+func BenchmarkParseIgnoreLines(b *testing.B) {
+	for _, count := range []int{10, 1000} {
+		b.Run(fmt.Sprint(count), func(b *testing.B) {
+			data := []byte(strings.Repeat("*.log\n# comment\n!keep.log\n", count))
+			b.ReportAllocs()
+			for b.Loop() {
+				m := gitignore.New("")
+				m.AddPatterns(data, "")
+			}
+		})
+	}
+}