path: root/tests/unit.rs

// Copyright 2013-2014 The rust-url developers.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

//! Unit tests

use std::borrow::Cow;
use std::cell::{Cell, RefCell};
use std::net::{Ipv4Addr, Ipv6Addr};
use std::path::{Path, PathBuf};
use url::{form_urlencoded, Host, Url};

#[test]
fn size() {
    use std::mem::size_of;
    assert_eq!(size_of::<Url>(), size_of::<Option<Url>>());
}

#[test]
fn test_relative() {
    let base: Url = "sc://%C3%B1".parse().unwrap();
    let url = base.join("/resources/testharness.js").unwrap();
    assert_eq!(url.as_str(), "sc://%C3%B1/resources/testharness.js");
}

#[test]
fn test_relative_empty() {
    let base: Url = "sc://%C3%B1".parse().unwrap();
    let url = base.join("").unwrap();
    assert_eq!(url.as_str(), "sc://%C3%B1");
}

#[test]
fn test_set_empty_host() {
    let mut base: Url = "moz://foo:bar@servo/baz".parse().unwrap();
    base.set_username("").unwrap();
    assert_eq!(base.as_str(), "moz://:bar@servo/baz");
    base.set_host(None).unwrap();
    assert_eq!(base.as_str(), "moz:/baz");
    base.set_host(Some("servo")).unwrap();
    assert_eq!(base.as_str(), "moz://servo/baz");
}

#[test]
fn test_set_empty_hostname() {
    use url::quirks;
    let mut base: Url = "moz://foo@servo/baz".parse().unwrap();
    assert!(
        quirks::set_hostname(&mut base, "").is_err(),
        "setting an empty hostname to a url with a username should fail"
    );
    base = "moz://:pass@servo/baz".parse().unwrap();
    assert!(
        quirks::set_hostname(&mut base, "").is_err(),
        "setting an empty hostname to a url with a password should fail"
    );
    base = "moz://servo/baz".parse().unwrap();
    quirks::set_hostname(&mut base, "").unwrap();
    assert_eq!(base.as_str(), "moz:///baz");
}

macro_rules! assert_from_file_path {
    ($path: expr) => {
        assert_from_file_path!($path, $path)
    };
    ($path: expr, $url_path: expr) => {{
        let url = Url::from_file_path(Path::new($path)).unwrap();
        assert_eq!(url.host(), None);
        assert_eq!(url.path(), $url_path);
        assert_eq!(url.to_file_path(), Ok(PathBuf::from($path)));
    }};
}

#[test]
fn new_file_paths() {
    if cfg!(unix) {
        assert_eq!(Url::from_file_path(Path::new("relative")), Err(()));
        assert_eq!(Url::from_file_path(Path::new("../relative")), Err(()));
    }
    if cfg!(windows) {
        assert_eq!(Url::from_file_path(Path::new("relative")), Err(()));
        assert_eq!(Url::from_file_path(Path::new(r"..\relative")), Err(()));
        assert_eq!(Url::from_file_path(Path::new(r"\drive-relative")), Err(()));
        assert_eq!(Url::from_file_path(Path::new(r"\\ucn\")), Err(()));
    }

    if cfg!(unix) {
        assert_from_file_path!("/foo/bar");
        assert_from_file_path!("/foo/ba\0r", "/foo/ba%00r");
        assert_from_file_path!("/foo/ba%00r", "/foo/ba%2500r");
    }
}

#[test]
#[cfg(unix)]
fn new_path_bad_utf8() {
    use std::ffi::OsStr;
    use std::os::unix::prelude::*;

    let url = Url::from_file_path(Path::new(OsStr::from_bytes(b"/foo/ba\x80r"))).unwrap();
    let os_str = OsStr::from_bytes(b"/foo/ba\x80r");
    assert_eq!(url.to_file_path(), Ok(PathBuf::from(os_str)));
}

#[test]
fn new_path_windows_fun() {
    if cfg!(windows) {
        assert_from_file_path!(r"C:\foo\bar", "/C:/foo/bar");
        assert_from_file_path!("C:\\foo\\ba\0r", "/C:/foo/ba%00r");

        // Invalid UTF-8
        assert!(Url::parse("file:///C:/foo/ba%80r")
            .unwrap()
            .to_file_path()
            .is_err());

        // test windows canonicalized path
        let path = PathBuf::from(r"\\?\C:\foo\bar");
        assert!(Url::from_file_path(path).is_ok());

        // Percent-encoded drive letter
        let url = Url::parse("file:///C%3A/foo/bar").unwrap();
        assert_eq!(url.to_file_path(), Ok(PathBuf::from(r"C:\foo\bar")));
    }
}

#[test]
fn new_directory_paths() {
    if cfg!(unix) {
        assert_eq!(Url::from_directory_path(Path::new("relative")), Err(()));
        assert_eq!(Url::from_directory_path(Path::new("../relative")), Err(()));

        let url = Url::from_directory_path(Path::new("/foo/bar")).unwrap();
        assert_eq!(url.host(), None);
        assert_eq!(url.path(), "/foo/bar/");
    }
    if cfg!(windows) {
        assert_eq!(Url::from_directory_path(Path::new("relative")), Err(()));
        assert_eq!(Url::from_directory_path(Path::new(r"..\relative")), Err(()));
        assert_eq!(
            Url::from_directory_path(Path::new(r"\drive-relative")),
            Err(())
        );
        assert_eq!(Url::from_directory_path(Path::new(r"\\ucn\")), Err(()));

        let url = Url::from_directory_path(Path::new(r"C:\foo\bar")).unwrap();
        assert_eq!(url.host(), None);
        assert_eq!(url.path(), "/C:/foo/bar/");
    }
}

#[test]
fn path_backslash_fun() {
    let mut special_url = "http://foobar.com".parse::<Url>().unwrap();
    special_url.path_segments_mut().unwrap().push("foo\\bar");
    assert_eq!(special_url.as_str(), "http://foobar.com/foo%5Cbar");

    let mut nonspecial_url = "thing://foobar.com".parse::<Url>().unwrap();
    nonspecial_url.path_segments_mut().unwrap().push("foo\\bar");
    assert_eq!(nonspecial_url.as_str(), "thing://foobar.com/foo\\bar");
}

#[test]
fn from_str() {
    assert!("http://testing.com/this".parse::<Url>().is_ok());
}

#[test]
fn parse_with_params() {
    let url = Url::parse_with_params(
        "http://testing.com/this?dont=clobberme",
        &[("lang", "rust")],
    )
    .unwrap();

    assert_eq!(
        url.as_str(),
        "http://testing.com/this?dont=clobberme&lang=rust"
    );
}

#[test]
fn issue_124() {
    let url: Url = "file:a".parse().unwrap();
    assert_eq!(url.path(), "/a");
    let url: Url = "file:...".parse().unwrap();
    assert_eq!(url.path(), "/...");
    let url: Url = "file:..".parse().unwrap();
    assert_eq!(url.path(), "/");
}

#[test]
fn test_equality() {
    use std::collections::hash_map::DefaultHasher;
    use std::hash::{Hash, Hasher};

    fn check_eq(a: &Url, b: &Url) {
        assert_eq!(a, b);

        let mut h1 = DefaultHasher::new();
        a.hash(&mut h1);
        let mut h2 = DefaultHasher::new();
        b.hash(&mut h2);
        assert_eq!(h1.finish(), h2.finish());
    }

    fn url(s: &str) -> Url {
        let rv = s.parse().unwrap();
        check_eq(&rv, &rv);
        rv
    }

    // Doesn't care if default port is given.
    let a: Url = url("https://example.com/");
    let b: Url = url("https://example.com:443/");
    check_eq(&a, &b);

    // Different ports
    let a: Url = url("http://example.com/");
    let b: Url = url("http://example.com:8080/");
    assert!(a != b, "{:?} != {:?}", a, b);

    // Different scheme
    let a: Url = url("http://example.com/");
    let b: Url = url("https://example.com/");
    assert_ne!(a, b);

    // Different host
    let a: Url = url("http://foo.com/");
    let b: Url = url("http://bar.com/");
    assert_ne!(a, b);

    // Missing path, automatically substituted. Semantically the same.
    let a: Url = url("http://foo.com");
    let b: Url = url("http://foo.com/");
    check_eq(&a, &b);
}

#[test]
fn host() {
    fn assert_host(input: &str, host: Host<&str>) {
        assert_eq!(Url::parse(input).unwrap().host(), Some(host));
    }
    assert_host("http://www.mozilla.org", Host::Domain("www.mozilla.org"));
    assert_host(
        "http://1.35.33.49",
        Host::Ipv4(Ipv4Addr::new(1, 35, 33, 49)),
    );
    assert_host(
        "http://[2001:0db8:85a3:08d3:1319:8a2e:0370:7344]",
        Host::Ipv6(Ipv6Addr::new(
            0x2001, 0x0db8, 0x85a3, 0x08d3, 0x1319, 0x8a2e, 0x0370, 0x7344,
        )),
    );
    assert_host("http://1.35.+33.49", Host::Domain("1.35.+33.49"));
    assert_host(
        "http://[::]",
        Host::Ipv6(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 0)),
    );
    assert_host(
        "http://[::1]",
        Host::Ipv6(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 1)),
    );
    assert_host(
        "http://0x1.0X23.0x21.061",
        Host::Ipv4(Ipv4Addr::new(1, 35, 33, 49)),
    );
    assert_host("http://0x1232131", Host::Ipv4(Ipv4Addr::new(1, 35, 33, 49)));
    assert_host("http://111", Host::Ipv4(Ipv4Addr::new(0, 0, 0, 111)));
    assert_host("http://2..2.3", Host::Domain("2..2.3"));
    assert!(Url::parse("http://42.0x1232131").is_err());
    assert!(Url::parse("http://192.168.0.257").is_err());

    assert_eq!(Host::Domain("foo"), Host::Domain("foo").to_owned());
    assert_ne!(Host::Domain("foo"), Host::Domain("bar").to_owned());
}

#[test]
fn host_serialization() {
    // libstd’s `Display for Ipv6Addr` serializes 0:0:0:0:0:0:_:_ and 0:0:0:0:0:ffff:_:_
    // using IPv4-like syntax, as suggested in https://tools.ietf.org/html/rfc5952#section-4
    // but https://url.spec.whatwg.org/#concept-ipv6-serializer specifies not to.

    // Not [::0.0.0.2] / [::ffff:0.0.0.2]
    assert_eq!(
        Url::parse("http://[0::2]").unwrap().host_str(),
        Some("[::2]")
    );
    assert_eq!(
        Url::parse("http://[0::ffff:0:2]").unwrap().host_str(),
        Some("[::ffff:0:2]")
    );
}

#[test]
fn test_idna() {
    assert!("http://goșu.ro".parse::<Url>().is_ok());
    assert_eq!(
        Url::parse("http://☃.net/").unwrap().host(),
        Some(Host::Domain("xn--n3h.net"))
    );
    assert!("https://r2---sn-huoa-cvhl.googlevideo.com/crossdomain.xml"
        .parse::<Url>()
        .is_ok());
}

#[test]
fn test_serialization() {
    let data = [
        ("http://example.com/", "http://example.com/"),
        ("http://addslash.com", "http://addslash.com/"),
        ("http://@emptyuser.com/", "http://emptyuser.com/"),
        ("http://:@emptypass.com/", "http://emptypass.com/"),
        ("http://user@user.com/", "http://user@user.com/"),
        (
            "http://user:pass@userpass.com/",
            "http://user:pass@userpass.com/",
        ),
        (
            "http://slashquery.com/path/?q=something",
            "http://slashquery.com/path/?q=something",
        ),
        (
            "http://noslashquery.com/path?q=something",
            "http://noslashquery.com/path?q=something",
        ),
    ];
    for &(input, result) in &data {
        let url = Url::parse(input).unwrap();
        assert_eq!(url.as_str(), result);
    }
}

#[test]
fn test_form_urlencoded() {
    let pairs: &[(Cow<'_, str>, Cow<'_, str>)] = &[
        ("foo".into(), "é&".into()),
        ("bar".into(), "".into()),
        ("foo".into(), "#".into()),
    ];
    let encoded = form_urlencoded::Serializer::new(String::new())
        .extend_pairs(pairs)
        .finish();
    assert_eq!(encoded, "foo=%C3%A9%26&bar=&foo=%23");
    assert_eq!(
        form_urlencoded::parse(encoded.as_bytes()).collect::<Vec<_>>(),
        pairs.to_vec()
    );
}

#[test]
fn test_form_serialize() {
    let encoded = form_urlencoded::Serializer::new(String::new())
        .append_pair("foo", "é&")
        .append_pair("bar", "")
        .append_pair("foo", "#")
        .append_key_only("json")
        .finish();
    assert_eq!(encoded, "foo=%C3%A9%26&bar=&foo=%23&json");
}

#[test]
fn form_urlencoded_encoding_override() {
    let encoded = form_urlencoded::Serializer::new(String::new())
        .encoding_override(Some(&|s| s.as_bytes().to_ascii_uppercase().into()))
        .append_pair("foo", "bar")
        .append_key_only("xml")
        .finish();
    assert_eq!(encoded, "FOO=BAR&XML");
}

#[test]
/// https://github.com/servo/rust-url/issues/61
fn issue_61() {
    let mut url = Url::parse("http://mozilla.org").unwrap();
    url.set_scheme("https").unwrap();
    assert_eq!(url.port(), None);
    assert_eq!(url.port_or_known_default(), Some(443));
    url.check_invariants().unwrap();
}

#[test]
#[cfg(not(windows))]
/// https://github.com/servo/rust-url/issues/197
fn issue_197() {
    let mut url = Url::from_file_path("/").expect("Failed to parse path");
    url.check_invariants().unwrap();
    assert_eq!(
        url,
        Url::parse("file:///").expect("Failed to parse path + protocol")
    );
    url.path_segments_mut()
        .expect("path_segments_mut")
        .pop_if_empty();
}

#[test]
fn issue_241() {
    Url::parse("mailto:").unwrap().cannot_be_a_base();
}

#[test]
/// https://github.com/servo/rust-url/issues/222
fn append_trailing_slash() {
    let mut url: Url = "http://localhost:6767/foo/bar?a=b".parse().unwrap();
    url.check_invariants().unwrap();
    url.path_segments_mut().unwrap().push("");
    url.check_invariants().unwrap();
    assert_eq!(url.to_string(), "http://localhost:6767/foo/bar/?a=b");
}

#[test]
/// https://github.com/servo/rust-url/issues/227
fn extend_query_pairs_then_mutate() {
    let mut url: Url = "http://localhost:6767/foo/bar".parse().unwrap();
    url.query_pairs_mut()
        .extend_pairs(vec![("auth", "my-token")].into_iter());
    url.check_invariants().unwrap();
    assert_eq!(
        url.to_string(),
        "http://localhost:6767/foo/bar?auth=my-token"
    );
    url.path_segments_mut().unwrap().push("some_other_path");
    url.check_invariants().unwrap();
    assert_eq!(
        url.to_string(),
        "http://localhost:6767/foo/bar/some_other_path?auth=my-token"
    );
}

#[test]
/// https://github.com/servo/rust-url/issues/222
fn append_empty_segment_then_mutate() {
    let mut url: Url = "http://localhost:6767/foo/bar?a=b".parse().unwrap();
    url.check_invariants().unwrap();
    url.path_segments_mut().unwrap().push("").pop();
    url.check_invariants().unwrap();
    assert_eq!(url.to_string(), "http://localhost:6767/foo/bar?a=b");
}

#[test]
/// https://github.com/servo/rust-url/issues/243
fn test_set_host() {
    let mut url = Url::parse("https://example.net/hello").unwrap();
    url.set_host(Some("foo.com")).unwrap();
    assert_eq!(url.as_str(), "https://foo.com/hello");
    assert!(url.set_host(None).is_err());
    assert_eq!(url.as_str(), "https://foo.com/hello");
    assert!(url.set_host(Some("")).is_err());
    assert_eq!(url.as_str(), "https://foo.com/hello");

    let mut url = Url::parse("foobar://example.net/hello").unwrap();
    url.set_host(None).unwrap();
    assert_eq!(url.as_str(), "foobar:/hello");

    let mut url = Url::parse("foo://ș").unwrap();
    assert_eq!(url.as_str(), "foo://%C8%99");
    url.set_host(Some("goșu.ro")).unwrap();
    assert_eq!(url.as_str(), "foo://go%C8%99u.ro");
}

#[test]
// https://github.com/servo/rust-url/issues/166
fn test_leading_dots() {
    assert_eq!(
        Host::parse(".org").unwrap(),
        Host::Domain(".org".to_owned())
    );
    assert_eq!(Url::parse("file://./foo").unwrap().domain(), Some("."));
}

#[test]
/// https://github.com/servo/rust-url/issues/302
fn test_origin_hash() {
    use std::collections::hash_map::DefaultHasher;
    use std::hash::{Hash, Hasher};

    fn hash<T: Hash>(value: &T) -> u64 {
        let mut hasher = DefaultHasher::new();
        value.hash(&mut hasher);
        hasher.finish()
    }

    let origin = &Url::parse("http://example.net/").unwrap().origin();

    let origins_to_compare = [
        Url::parse("http://example.net:80/").unwrap().origin(),
        Url::parse("http://example.net:81/").unwrap().origin(),
        Url::parse("http://example.net").unwrap().origin(),
        Url::parse("http://example.net/hello").unwrap().origin(),
        Url::parse("https://example.net").unwrap().origin(),
        Url::parse("ftp://example.net").unwrap().origin(),
        Url::parse("file://example.net").unwrap().origin(),
        Url::parse("http://user@example.net/").unwrap().origin(),
        Url::parse("http://user:pass@example.net/")
            .unwrap()
            .origin(),
    ];

    for origin_to_compare in &origins_to_compare {
        if origin == origin_to_compare {
            assert_eq!(hash(origin), hash(origin_to_compare));
        } else {
            assert_ne!(hash(origin), hash(origin_to_compare));
        }
    }

    let opaque_origin = Url::parse("file://example.net").unwrap().origin();
    let same_opaque_origin = Url::parse("file://example.net").unwrap().origin();
    let other_opaque_origin = Url::parse("file://other").unwrap().origin();

    assert_ne!(hash(&opaque_origin), hash(&same_opaque_origin));
    assert_ne!(hash(&opaque_origin), hash(&other_opaque_origin));
}

#[test]
fn test_windows_unc_path() {
    if !cfg!(windows) {
        return;
    }

    let url = Url::from_file_path(Path::new(r"\\host\share\path\file.txt")).unwrap();
    assert_eq!(url.as_str(), "file://host/share/path/file.txt");

    let url = Url::from_file_path(Path::new(r"\\höst\share\path\file.txt")).unwrap();
    assert_eq!(url.as_str(), "file://xn--hst-sna/share/path/file.txt");

    let url = Url::from_file_path(Path::new(r"\\192.168.0.1\share\path\file.txt")).unwrap();
    assert_eq!(url.host(), Some(Host::Ipv4(Ipv4Addr::new(192, 168, 0, 1))));

    let path = url.to_file_path().unwrap();
    assert_eq!(path.to_str(), Some(r"\\192.168.0.1\share\path\file.txt"));

    // Another way to write these:
    let url = Url::from_file_path(Path::new(r"\\?\UNC\host\share\path\file.txt")).unwrap();
    assert_eq!(url.as_str(), "file://host/share/path/file.txt");

    // Paths starting with "\\.\" (Local Device Paths) are intentionally not supported.
    let url = Url::from_file_path(Path::new(r"\\.\some\path\file.txt"));
    assert!(url.is_err());
}

#[test]
fn test_syntax_violation_callback() {
    use url::SyntaxViolation::*;
    let violation = Cell::new(None);
    let url = Url::options()
        .syntax_violation_callback(Some(&|v| violation.set(Some(v))))
        .parse("http:////mozilla.org:42")
        .unwrap();
    assert_eq!(url.port(), Some(42));

    let v = violation.take().unwrap();
    assert_eq!(v, ExpectedDoubleSlash);
    assert_eq!(v.description(), "expected //");
    assert_eq!(v.to_string(), "expected //");
}

#[test]
fn test_syntax_violation_callback_lifetimes() {
    use url::SyntaxViolation::*;
    let violation = Cell::new(None);
    let vfn = |s| violation.set(Some(s));

    let url = Url::options()
        .syntax_violation_callback(Some(&vfn))
        .parse("http:////mozilla.org:42")
        .unwrap();
    assert_eq!(url.port(), Some(42));
    assert_eq!(violation.take(), Some(ExpectedDoubleSlash));

    let url = Url::options()
        .syntax_violation_callback(Some(&vfn))
        .parse("http://mozilla.org\\path")
        .unwrap();
    assert_eq!(url.path(), "/path");
    assert_eq!(violation.take(), Some(Backslash));
}

#[test]
fn test_options_reuse() {
    use url::SyntaxViolation::*;
    let violations = RefCell::new(Vec::new());
    let vfn = |v| violations.borrow_mut().push(v);

    let options = Url::options().syntax_violation_callback(Some(&vfn));
    let url = options.parse("http:////mozilla.org").unwrap();

    let options = options.base_url(Some(&url));
    let url = options.parse("/sub\\path").unwrap();
    assert_eq!(url.as_str(), "http://mozilla.org/sub/path");
    assert_eq!(*violations.borrow(), vec!(ExpectedDoubleSlash, Backslash));
}

/// https://github.com/servo/rust-url/issues/505
#[cfg(windows)]
#[test]
fn test_url_from_file_path() {
    use std::path::PathBuf;
    use url::Url;

    let p = PathBuf::from("c:///");
    let u = Url::from_file_path(p).unwrap();
    let path = u.to_file_path().unwrap();
    assert_eq!("C:\\", path.to_str().unwrap());
}

/// https://github.com/servo/rust-url/issues/505
#[cfg(not(windows))]
#[test]
fn test_url_from_file_path() {
    use std::path::PathBuf;
    use url::Url;

    let p = PathBuf::from("/c:/");
    let u = Url::from_file_path(p).unwrap();
    let path = u.to_file_path().unwrap();
    assert_eq!("/c:/", path.to_str().unwrap());
}

#[test]
fn test_non_special_path() {
    let mut db_url = url::Url::parse("postgres://postgres@localhost/").unwrap();
    assert_eq!(db_url.as_str(), "postgres://postgres@localhost/");
    db_url.set_path("diesel_foo");
    assert_eq!(db_url.as_str(), "postgres://postgres@localhost/diesel_foo");
    assert_eq!(db_url.path(), "/diesel_foo");
}

#[test]
fn test_non_special_path2() {
    let mut db_url = url::Url::parse("postgres://postgres@localhost/").unwrap();
    assert_eq!(db_url.as_str(), "postgres://postgres@localhost/");
    db_url.set_path("");
    assert_eq!(db_url.path(), "");
    assert_eq!(db_url.as_str(), "postgres://postgres@localhost");
    db_url.set_path("foo");
    assert_eq!(db_url.path(), "/foo");
    assert_eq!(db_url.as_str(), "postgres://postgres@localhost/foo");
    db_url.set_path("/bar");
    assert_eq!(db_url.path(), "/bar");
    assert_eq!(db_url.as_str(), "postgres://postgres@localhost/bar");
}

#[test]
fn test_non_special_path3() {
    let mut db_url = url::Url::parse("postgres://postgres@localhost/").unwrap();
    assert_eq!(db_url.as_str(), "postgres://postgres@localhost/");
    db_url.set_path("/");
    assert_eq!(db_url.as_str(), "postgres://postgres@localhost/");
    assert_eq!(db_url.path(), "/");
    db_url.set_path("/foo");
    assert_eq!(db_url.as_str(), "postgres://postgres@localhost/foo");
    assert_eq!(db_url.path(), "/foo");
}

#[test]
fn test_set_scheme_to_file_with_host() {
    let mut url: Url = "http://localhost:6767/foo/bar".parse().unwrap();
    let result = url.set_scheme("file");
    assert_eq!(url.to_string(), "http://localhost:6767/foo/bar");
    assert_eq!(result, Err(()));
}

#[test]
fn no_panic() {
    let mut url = Url::parse("arhttpsps:/.//eom/dae.com/\\\\t\\:").unwrap();
    url::quirks::set_hostname(&mut url, "//eom/datcom/\\\\t\\://eom/data.cs").unwrap();
}

#[test]
fn pop_if_empty_in_bounds() {
    let mut url = Url::parse("m://").unwrap();
    let mut segments = url.path_segments_mut().unwrap();
    segments.pop_if_empty();
    segments.pop();
}