More work on porting diff kitten

tools/cmd/diff/collect.go

@@ -0,0 +1,48 @@
+// License: GPLv3 Copyright: 2023, Kovid Goyal, <kovid at kovidgoyal.net>
+
+package diff
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+)
+
+var _ = fmt.Print
+var path_name_map, remote_dirs map[string]string
+
+type Collection struct {
+}
+
+func create_collection(left, right string) (ans *Collection, err error) {
+	path_name_map = make(map[string]string, 32)
+	remote_dirs = make(map[string]string, 32)
+	ans = &Collection{}
+	left_stat, err := os.Stat(left)
+	if err != nil {
+		return nil, err
+	}
+	if left_stat.IsDir() {
+		err = ans.collect_files(left, right)
+		if err != nil {
+			return nil, err
+		}
+	} else {
+		pl, err := filepath.Abs(left)
+		if err != nil {
+			return nil, err
+		}
+		pr, err := filepath.Abs(right)
+		if err != nil {
+			return nil, err
+		}
+		path_name_map[pl] = resolve_remote_name(pl, left)
+		path_name_map[pr] = resolve_remote_name(pr, right)
+		err = ans.add_change(pl, pr)
+		if err != nil {
+			return nil, err
+		}
+	}
+	err = ans.finalize()
+	return ans, err
+}