More work on porting the diff kitten

tools/cmd/diff/collect.go

@@ -4,13 +4,64 @@ package diff
 
 import (
 	"fmt"
+	"kitty/tools/utils"
 	"os"
 	"path/filepath"
+	"strings"
 )
 
 var _ = fmt.Print
 var path_name_map, remote_dirs map[string]string
 
+var mimetypes_cache, data_cache *utils.LRUCache[string, string]
+var lines_cache *utils.LRUCache[string, []string]
+
+func init_caches() {
+	mimetypes_cache = utils.NewLRUCache[string, string](4096)
+	data_cache = utils.NewLRUCache[string, string](4096)
+	lines_cache = utils.NewLRUCache[string, []string](4096)
+}
+
+func mimetype_for_path(path string) string {
+	return mimetypes_cache.MustGetOrCreate(path, func(path string) string {
+		mt := utils.GuessMimeTypeWithFileSystemAccess(path)
+		if mt == "" {
+			mt = "application/octet-stream"
+		}
+		if utils.KnownTextualMimes[mt] {
+			if _, a, found := strings.Cut(mt, "/"); found {
+				mt = "text/" + a
+			}
+		}
+		return mt
+	})
+}
+
+func data_for_path(path string) (string, error) {
+	return data_cache.GetOrCreate(path, func(path string) (string, error) {
+		ans, err := os.ReadFile(path)
+		return utils.UnsafeBytesToString(ans), err
+	})
+}
+
+func sanitize(x string) string {
+	x = strings.ReplaceAll(x, "\r\n", "⏎\n")
+	return utils.SanitizeControlCodes(x, "░")
+}
+
+func lines_for_path(path string) ([]string, error) {
+	return lines_cache.GetOrCreate(path, func(path string) ([]string, error) {
+		ans, err := data_for_path(path)
+		if err != nil {
+			return nil, err
+		}
+		ans = sanitize(strings.ReplaceAll(ans, "\t", conf.Replace_tab_by))
+		lines := make([]string, 0, 256)
+		splitlines_like_git(ans, false, func(line string) { lines = append(lines, line) })
+		return lines, nil
+	})
+}
+
 type Collection struct {
 }