如何在Rust git2中获取`git2 diff master <commit>:<directory>`的行为

[dependencies]
git2 = "0.13"

extern crate git2;

use git2::{Repository, DiffOptions, DiffFormat};

let repo = Repository::open("/path/to/repository").unwrap();
let commit1 = repo.revparse_single("master").unwrap();
let commit2 = repo.revparse_single("<commit>").unwrap();

let mut diff_options = DiffOptions::new();
diff_options.pathspec("<directory>");

let diff = repo.diff(Some(&commit1), Some(&commit2), Some(&mut diff_options)).unwrap();

diff.foreach(
    &mut |delta, _progress| {
        let old_file = delta.old_file();
        let new_file = delta.new_file();

        // 获取文件差异的行为
        let diff_lines = diff.lines_in(delta).unwrap();

        // 处理差异行为
        for diff_line in diff_lines {
            // 在这里可以获取每一行的行号、内容等信息
            // 进行相应的处理
        }

        true
    },
    None,
    None,
    None,
).unwrap();