path: root/src/libcore/path.rs

#[doc = "Path data type and helper functions"];

export path;
export consts;
export path_is_absolute;
export path_sep;
export dirname;
export basename;
export connect;
export connect_many;
export split;
export splitext;
export normalize;

// FIXME: This type should probably be constrained (#2624)
#[doc = "A path or fragment of a filesystem path"]
type path = str;

#[cfg(unix)]
mod consts {
    #[doc = "
    The primary path separator character for the platform

    On all platforms it is '/'
    "]
    const path_sep: char = '/';
    #[doc = "
    The secondary path separator character for the platform

    On Unixes it is '/'. On Windows it is '\\'.
    "]
    const alt_path_sep: char = '/';
}

#[cfg(windows)]
mod consts {
    const path_sep: char = '/';
    const alt_path_sep: char = '\\';
}

#[doc = "
Indicates whether a path is absolute.

A path is considered absolute if it begins at the filesystem root (\"/\") or,
on Windows, begins with a drive letter.
"]
#[cfg(unix)]
fn path_is_absolute(p: path) -> bool {
    str::char_at(p, 0u) == '/'
}

#[cfg(windows)]
fn path_is_absolute(p: str) -> bool {
    ret str::char_at(p, 0u) == '/' ||
        str::char_at(p, 1u) == ':'
        && (str::char_at(p, 2u) == consts::path_sep
            || str::char_at(p, 2u) == consts::alt_path_sep);
}

#[doc = "Get the default path separator for the host platform"]
fn path_sep() -> str { ret str::from_char(consts::path_sep); }

fn split_dirname_basename (pp: path) -> {dirname: str, basename: str} {
    alt str::rfind(pp, {|ch|
        ch == consts::path_sep || ch == consts::alt_path_sep
    }) {
      some(i) {
        {dirname: str::slice(pp, 0u, i),
         basename: str::slice(pp, i + 1u, str::len(pp))}
      }
      none { {dirname: ".", basename: pp} }
    }
}

#[doc = "
Get the directory portion of a path

Returns all of the path up to, but excluding, the final path separator.
The dirname of \"/usr/share\" will be \"/usr\", but the dirname of
\"/usr/share/\" is \"/usr/share\".

If the path is not prefixed with a directory, then \".\" is returned.
"]
fn dirname(pp: path) -> path {
    ret split_dirname_basename(pp).dirname;
}

#[doc = "
Get the file name portion of a path

Returns the portion of the path after the final path separator.
The basename of \"/usr/share\" will be \"share\". If there are no
path separators in the path then the returned path is identical to
the provided path. If an empty path is provided or the path ends
with a path separator then an empty path is returned.
"]
fn basename(pp: path) -> path {
    ret split_dirname_basename(pp).basename;
}

#[doc = "
Connects to path segments

Given paths `pre` and `post, removes any trailing path separator on `pre` and
any leading path separator on `post`, and returns the concatenation of the two
with a single path separator between them.
"]
fn connect(pre: path, post: path) -> path {
    let mut pre_ = pre;
    let mut post_ = post;
    let sep = consts::path_sep as u8;
    let pre_len  = str::len(pre);
    let post_len = str::len(post);
    unsafe {
        if pre_len > 1u && pre[pre_len-1u] == sep {
            str::unsafe::pop_byte(pre_);
        }
        if post_len > 1u && post[0] == sep {
            str::unsafe::shift_byte(post_);
        }
    }
    ret pre_ + path_sep() + post_;
}

#[doc = "
Connects a vector of path segments into a single path.

Inserts path separators as needed.
"]
fn connect_many(paths: [path]/~) -> path {
    ret if vec::len(paths) == 1u {
        paths[0]
    } else {
        let rest = vec::slice(paths, 1u, vec::len(paths));
        connect(paths[0], connect_many(rest))
    }
}

#[doc = "
Split a path into its individual components

Splits a given path by path separators and returns a vector containing
each piece of the path. On Windows, if the path is absolute then
the first element of the returned vector will be the drive letter
followed by a colon.
"]
fn split(p: path) -> [path]/~ {
    str::split_nonempty(p, {|c|
        c == consts::path_sep || c == consts::alt_path_sep
    })
}

#[doc = "
Split a path into the part before the extension and the extension

Split a path into a pair of strings with the first element being the filename
without the extension and the second being either empty or the file extension
including the period. Leading periods in the basename are ignored.  If the
path includes directory components then they are included in the filename part
of the result pair.
"]
fn splitext(p: path) -> (str, str) {
    if str::is_empty(p) { ("", "") }
    else {
        let parts = str::split_char(p, '.');
        if vec::len(parts) > 1u {
            let base = str::connect(vec::init(parts), ".");
            // We just checked that parts is non-empty, so this is safe
            let ext = "." + vec::last(parts);

            fn is_dotfile(base: str) -> bool {
                str::is_empty(base)
                    || str::ends_with(
                        base, str::from_char(consts::path_sep))
                    || str::ends_with(
                        base, str::from_char(consts::alt_path_sep))
            }

            fn ext_contains_sep(ext: str) -> bool {
                vec::len(split(ext)) > 1u
            }

            fn no_basename(ext: str) -> bool {
                str::ends_with(
                    ext, str::from_char(consts::path_sep))
                    || str::ends_with(
                        ext, str::from_char(consts::alt_path_sep))
            }

            if is_dotfile(base)
                || ext_contains_sep(ext)
                || no_basename(ext) {
                (p, "")
            } else {
                (base, ext)
            }
        } else {
            (p, "")
        }
    }
}

#[doc = "
Collapses redundant path separators.

Does not follow symbolic links.

# Examples

* '/a/../b' becomes '/b'
* 'a/./b/' becomes 'a/b/'
* 'a/b/../../../' becomes '..'
* '/a/b/c/../d/./../../e/' becomes '/a/e/'

"]
fn normalize(p: path) -> path {
    let s = split(p);
    let s = strip_dots(s);
    let s = rollup_doubledots(s);

    let s = if check vec::is_not_empty(s) {
        connect_many(s)
    } else {
        ""
    };
    let s = reabsolute(p, s);
    let s = reterminate(p, s);

    let s = if str::len(s) == 0u {
        "."
    } else {
        s
    };

    ret s;

    fn strip_dots(s: [path]/~) -> [path]/~ {
        vec::filter_map(s, { |elem|
            if elem == "." {
                option::none
            } else {
                option::some(elem)
            }
        })
    }

    fn rollup_doubledots(s: [path]/~) -> [path]/~ {
        if vec::is_empty(s) {
            ret []/~;
        }

        let mut t = []/~;
        let mut i = vec::len(s);
        let mut skip = 0;
        while i != 0u {
            i -= 1u;
            if s[i] == ".." {
                skip += 1;
            } else {
                if skip == 0 {
                    vec::push(t, s[i]);
                } else {
                    skip -= 1;
                }
            }
        }
        let mut t = vec::reversed(t);
        while skip > 0 {
            vec::push(t, "..");
            skip -= 1;
        }
        ret t;
    }

    #[cfg(unix)]
    fn reabsolute(orig: path, n: path) -> path {
        if path_is_absolute(orig) {
            path_sep() + n
        } else {
            n
        }
    }

    #[cfg(windows)]
    fn reabsolute(orig: path, newp: path) -> path {
       if path_is_absolute(orig) && orig[0] == consts::path_sep as u8 {
           str::from_char(consts::path_sep) + newp
       } else {
           newp
       }
    }

    fn reterminate(orig: path, newp: path) -> path {
        let last = orig[str::len(orig) - 1u];
        if last == consts::path_sep as u8
            || last == consts::path_sep as u8 {
            ret newp + path_sep();
        } else {
            ret newp;
        }
    }
}

#[cfg(test)]
mod tests {
    #[test]
    fn test_connect() {
        let slash = path_sep();
        log(error, connect("a", "b"));
        assert (connect("a", "b") == "a" + slash + "b");
        assert (connect("a" + slash, "b") == "a" + slash + "b");
    }

    fn ps() -> str {
        path_sep()
    }

    fn aps() -> str {
        "/"
    }

    #[test]
    fn split1() {
        let actual = split("a" + ps() + "b");
        let expected = ["a", "b"]/~;
        assert actual == expected;
    }

    #[test]
    fn split2() {
        let actual = split("a" + aps() + "b");
        let expected = ["a", "b"]/~;
        assert actual == expected;
    }

    #[test]
    fn split3() {
        let actual = split(ps() + "a" + ps() + "b");
        let expected = ["a", "b"]/~;
        assert actual == expected;
    }

    #[test]
    fn split4() {
        let actual = split("a" + ps() + "b" + aps() + "c");
        let expected = ["a", "b", "c"]/~;
        assert actual == expected;
    }

    #[test]
    fn normalize1() {
        let actual = normalize("a/b/..");
        let expected = "a";
        assert actual == expected;
    }

    #[test]
    fn normalize2() {
        let actual = normalize("/a/b/..");
        let expected = "/a";
        assert actual == expected;
    }

    #[test]
    fn normalize3() {
        let actual = normalize("a/../b");
        let expected = "b";
        assert actual == expected;
    }

    #[test]
    fn normalize4() {
        let actual = normalize("/a/../b");
        let expected = "/b";
        assert actual == expected;
    }

    #[test]
    fn normalize5() {
        let actual = normalize("a/.");
        let expected = "a";
        assert actual == expected;
    }

    #[test]
    fn normalize6() {
        let actual = normalize("a/./b/");
        let expected = "a/b/";
        assert actual == expected;
    }

    #[test]
    fn normalize7() {
        let actual = normalize("a/..");
        let expected = ".";
        assert actual == expected;
    }

    #[test]
    fn normalize8() {
        let actual = normalize("../../..");
        let expected = "../../..";
        assert actual == expected;
    }

    #[test]
    fn normalize9() {
        let actual = normalize("a/b/../../..");
        let expected = "..";
        assert actual == expected;
    }

    #[test]
    fn normalize10() {
        let actual = normalize("/a/b/c/../d/./../../e/");
        let expected = "/a/e/";
        log(error, actual);
        assert actual == expected;
    }

    #[test]
    fn normalize11() {
        let actual = normalize("/a/..");
        let expected = "/";
        assert actual == expected;
    }

    #[test]
    #[cfg(windows)]
    fn normalize12() {
        let actual = normalize("C:/whatever");
        let expected = "C:/whatever";
        log(error, actual);
        assert actual == expected;
    }

    #[test]
    #[cfg(windows)]
    fn path_is_absolute_win32() {
        assert path_is_absolute("C:/whatever");
    }

    #[test]
    fn splitext_empty() {
        let (base, ext) = splitext("");
        assert base == "";
        assert ext == "";
    }

    #[test]
    fn splitext_ext() {
        let (base, ext) = splitext("grum.exe");
        assert base == "grum";
        assert ext == ".exe";
    }

    #[test]
    fn splitext_noext() {
        let (base, ext) = splitext("grum");
        assert base == "grum";
        assert ext == "";
    }

    #[test]
    fn splitext_dotfile() {
        let (base, ext) = splitext(".grum");
        assert base == ".grum";
        assert ext == "";
    }

    #[test]
    fn splitext_path_ext() {
        let (base, ext) = splitext("oh/grum.exe");
        assert base == "oh/grum";
        assert ext == ".exe";
    }

    #[test]
    fn splitext_path_noext() {
        let (base, ext) = splitext("oh/grum");
        assert base == "oh/grum";
        assert ext == "";
    }

    #[test]
    fn splitext_dot_in_path() {
        let (base, ext) = splitext("oh.my/grum");
        assert base == "oh.my/grum";
        assert ext == "";
    }

    #[test]
    fn splitext_nobasename() {
        let (base, ext) = splitext("oh.my/");
        assert base == "oh.my/";
        assert ext == "";
    }
}

// Local Variables:
// mode: rust;
// fill-column: 78;
// indent-tabs-mode: nil
// c-basic-offset: 4
// buffer-file-coding-system: utf-8-unix
// End: