// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// 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.

/*!

Cross-platform file path handling

*/

#[allow(missing_doc)];

use c_str::ToCStr;
use c_str;
use clone::Clone;
use cmp::Eq;
use container::Container;
use iter::{Iterator, range};
use libc;
use num;
use option::{None, Option, Some};
use str::{OwnedStr, Str, StrSlice, StrVector};
use to_str::ToStr;
use ascii::{AsciiCast, AsciiStr};
use vec::{Vector, OwnedVector, ImmutableVector, OwnedCopyableVector};

#[cfg(windows)]
pub use Path = self::WindowsPath;
#[cfg(unix)]
pub use Path = self::PosixPath;

#[deriving(Clone, Eq)]
pub struct WindowsPath {
    host: Option<~str>,
    device: Option<~str>,
    is_absolute: bool,
    components: ~[~str],
}

pub fn WindowsPath(s: &str) -> WindowsPath {
    GenericPath::from_str(s)
}

#[deriving(Clone, Eq)]
pub struct PosixPath {
    is_absolute: bool,
    components: ~[~str],
}

pub fn PosixPath(s: &str) -> PosixPath {
    GenericPath::from_str(s)
}

pub trait GenericPath : Clone + Eq + ToStr {
    /// Converts a string to a path.
    fn from_str(&str) -> Self;

    /// Returns the directory component of `self`, as a string.
    fn dirname(&self) -> ~str {
        let s = self.dir_path().to_str();
        match s.len() {
            0 => ~".",
            _ => s,
        }
    }

    /// Returns the file component of `self`, as a string option.
    /// Returns None if `self` names a directory.
    fn filename<'a>(&'a self) -> Option<&'a str> {
        match self.components().len() {
            0 => None,
            n => Some(self.components()[n - 1].as_slice()),
        }
    }

    /// Returns the stem of the file component of `self`, as a string option.
    /// The stem is the slice of a filename starting at 0 and ending just before
    /// the last '.' in the name.
    /// Returns None if `self` names a directory.
    fn filestem<'a>(&'a self) -> Option<&'a str> {
        match self.filename() {
            None => None,
            Some(ref f) => {
                match f.rfind('.') {
                    Some(p) => Some(f.slice_to(p)),
                    None => Some((*f)),
                }
            }
        }
    }

    /// Returns the type of the file component of `self`, as a string option.
    /// The file type is the slice of a filename starting just after the last
    /// '.' in the name and ending at the last index in the filename.
    /// Returns None if `self` names a directory.
    fn filetype<'a>(&'a self) -> Option<&'a str> {
        match self.filename() {
            None => None,
            Some(ref f) => {
                match f.rfind('.') {
                    Some(p) if p < f.len() => Some(f.slice_from(p)),
                    _ => None,
                }
            }
        }
    }

    /// Returns a new path consisting of `self` with the parent directory component replaced
    /// with the given string.
    fn with_dirname(&self, (&str)) -> Self;

    /// Returns a new path consisting of `self` with the file component replaced
    /// with the given string.
    fn with_filename(&self, (&str)) -> Self;

    /// Returns a new path consisting of `self` with the file stem replaced
    /// with the given string.
    fn with_filestem(&self, s: &str) -> Self {
        match self.filetype() {
            None => self.with_filename(s),
            Some(ref t) => self.with_filename(s.to_owned() + *t),
        }
    }

    /// Returns a new path consisting of `self` with the file type replaced
    /// with the given string.
    fn with_filetype(&self, t: &str) -> Self {
        match (t.len(), self.filestem()) {
            (0, None)        => (*self).clone(),
            (0, Some(ref s)) => self.with_filename(*s),
            (_, None)        => self.with_filename(fmt!(".%s", t)),
            (_, Some(ref s)) => self.with_filename(fmt!("%s.%s", *s, t)),
        }
    }

    /// Returns the directory component of `self`, as a new path.
    /// If `self` has no parent, returns `self`.
    fn dir_path(&self) -> Self {
        match self.components().len() {
            0 => (*self).clone(),
            _ => self.pop(),
        }
    }

    /// Returns the file component of `self`, as a new path.
    /// If `self` names a directory, returns the empty path.
    fn file_path(&self) -> Self;

    /// Returns a new path whose parent directory is `self` and whose
    /// file component is the given string.
    fn push(&self, (&str)) -> Self;

    /// Returns a new path consisting of the given path, made relative to `self`.
    fn push_rel(&self, other: &Self) -> Self {
        assert!(!other.is_absolute());
        self.push_many(other.components())
    }

    /// Returns a new path consisting of the path given by the given vector
    /// of strings, relative to `self`.
    fn push_many<S: Str>(&self, (&[S])) -> Self;

    /// Identical to `dir_path` except in the case where `self` has only one
    /// component. In this case, `pop` returns the empty path.
    fn pop(&self) -> Self;

    /// The same as `push_rel`, except that the directory argument must not
    /// contain directory separators in any of its components.
    fn unsafe_join(&self, (&Self)) -> Self;

    /// On Unix, always returns `false`. On Windows, returns `true` iff `self`'s
    /// file stem is one of: `con` `aux` `com1` `com2` `com3` `com4`
    /// `lpt1` `lpt2` `lpt3` `prn` `nul`.
    fn is_restricted(&self) -> bool;

    /// Returns a new path that names the same file as `self`, without containing
    /// any '.', '..', or empty components. On Windows, uppercases the drive letter
    /// as well.
    fn normalize(&self) -> Self;

    /// Returns `true` if `self` is an absolute path.
    fn is_absolute(&self) -> bool;

    /// True if `self` is an ancestor of `other`.
    // See `test_is_ancestor_of` for examples.
    fn is_ancestor_of(&self, other: &Self) -> bool {
        debug!("%s / %s %? %?", self.to_str(), other.to_str(), self.is_absolute(),
               self.components().len());
        self == other ||
            (!other.components().is_empty() &&
             !(self.components().is_empty() && !self.is_absolute()) &&
             self.is_ancestor_of(&other.pop()))
    }

    /// Finds the relative path from one file to another.
    fn get_relative_to(&self, abs2: (&Self)) -> Self {
        assert!(self.is_absolute());
        assert!(abs2.is_absolute());
        let abs1 = self.normalize();
        let abs2 = abs2.normalize();

        let split1: &[~str] = abs1.components();
        let split2: &[~str] = abs2.components();
        let len1 = split1.len();
        let len2 = split2.len();
        assert!(len1 > 0);
        assert!(len2 > 0);

        let max_common_path = num::min(len1, len2) - 1;
        let mut start_idx = 0;
        while start_idx < max_common_path
            && split1[start_idx] == split2[start_idx] {
            start_idx += 1;
        }

        let mut path: ~[~str] = ~[];
        for _ in range(start_idx, len1 - 1) { path.push(~".."); };

        path.push_all(split2.slice(start_idx, len2 - 1));

        let mut result: Self = GenericPath::from_str(".");
        if !path.is_empty() {
            // Without this type hint, the typechecker doesn't seem to like it
            let p: Self = GenericPath::from_str("");
            result = p.push_many(path);
        };
        result
    }


    /// Returns `true` iff `child` is a suffix of `parent`. See the test
    /// case for examples.
    pub fn is_parent_of(parent: &Path, child: &Path) -> bool {
        if !parent.is_absolute() || child.is_absolute()
            || parent.components.len() < child.components.len()
            || parent.components.is_empty() {
            return false;
        }
        let child_components = child.components().len();
        let parent_components = parent.components().len();
        let to_drop = parent.components.len() - child_components;
        parent.components.slice(to_drop, parent_components) == child.components
    }

    fn components<'a>(&'a self) -> &'a [~str];
}

#[cfg(target_os = "linux")]
#[cfg(target_os = "android")]
mod stat {
    #[cfg(target_arch = "x86")]
    pub mod arch {
        use libc;

        pub fn default_stat() -> libc::stat {
            libc::stat {
                st_dev: 0,
                __pad1: 0,
                st_ino: 0,
                st_mode: 0,
                st_nlink: 0,
                st_uid: 0,
                st_gid: 0,
                st_rdev: 0,
                __pad2: 0,
                st_size: 0,
                st_blksize: 0,
                st_blocks: 0,
                st_atime: 0,
                st_atime_nsec: 0,
                st_mtime: 0,
                st_mtime_nsec: 0,
                st_ctime: 0,
                st_ctime_nsec: 0,
                __unused4: 0,
                __unused5: 0,
            }
        }
    }

    #[cfg(target_arch = "arm")]
    pub mod arch {
        use libc;

        pub fn default_stat() -> libc::stat {
            libc::stat {
                st_dev: 0,
                __pad0: [0, ..4],
                __st_ino: 0,
                st_mode: 0,
                st_nlink: 0,
                st_uid: 0,
                st_gid: 0,
                st_rdev: 0,
                __pad3: [0, ..4],
                st_size: 0,
                st_blksize: 0,
                st_blocks: 0,
                st_atime: 0,
                st_atime_nsec: 0,
                st_mtime: 0,
                st_mtime_nsec: 0,
                st_ctime: 0,
                st_ctime_nsec: 0,
                st_ino: 0
            }
        }
    }

    #[cfg(target_arch = "mips")]
    pub mod arch {
        use libc;

        pub fn default_stat() -> libc::stat {
            libc::stat {
                st_dev: 0,
                st_pad1: [0, ..3],
                st_ino: 0,
                st_mode: 0,
                st_nlink: 0,
                st_uid: 0,
                st_gid: 0,
                st_rdev: 0,
                st_pad2: [0, ..2],
                st_size: 0,
                st_pad3: 0,
                st_atime: 0,
                st_atime_nsec: 0,
                st_mtime: 0,
                st_mtime_nsec: 0,
                st_ctime: 0,
                st_ctime_nsec: 0,
                st_blksize: 0,
                st_blocks: 0,
                st_pad5: [0, ..14],
            }
        }
    }

    #[cfg(target_arch = "x86_64")]
    pub mod arch {
        use libc;

        pub fn default_stat() -> libc::stat {
            libc::stat {
                st_dev: 0,
                st_ino: 0,
                st_nlink: 0,
                st_mode: 0,
                st_uid: 0,
                st_gid: 0,
                __pad0: 0,
                st_rdev: 0,
                st_size: 0,
                st_blksize: 0,
                st_blocks: 0,
                st_atime: 0,
                st_atime_nsec: 0,
                st_mtime: 0,
                st_mtime_nsec: 0,
                st_ctime: 0,
                st_ctime_nsec: 0,
                __unused: [0, 0, 0],
            }
        }
    }
}

#[cfg(target_os = "freebsd")]
mod stat {
    #[cfg(target_arch = "x86_64")]
    pub mod arch {
        use libc;

        pub fn default_stat() -> libc::stat {
            libc::stat {
                st_dev: 0,
                st_ino: 0,
                st_mode: 0,
                st_nlink: 0,
                st_uid: 0,
                st_gid: 0,
                st_rdev: 0,
                st_atime: 0,
                st_atime_nsec: 0,
                st_mtime: 0,
                st_mtime_nsec: 0,
                st_ctime: 0,
                st_ctime_nsec: 0,
                st_size: 0,
                st_blocks: 0,
                st_blksize: 0,
                st_flags: 0,
                st_gen: 0,
                st_lspare: 0,
                st_birthtime: 0,
                st_birthtime_nsec: 0,
                __unused: [0, 0],
            }
        }
    }
}

#[cfg(target_os = "macos")]
mod stat {
    pub mod arch {
        use libc;

        pub fn default_stat() -> libc::stat {
            libc::stat {
                st_dev: 0,
                st_mode: 0,
                st_nlink: 0,
                st_ino: 0,
                st_uid: 0,
                st_gid: 0,
                st_rdev: 0,
                st_atime: 0,
                st_atime_nsec: 0,
                st_mtime: 0,
                st_mtime_nsec: 0,
                st_ctime: 0,
                st_ctime_nsec: 0,
                st_birthtime: 0,
                st_birthtime_nsec: 0,
                st_size: 0,
                st_blocks: 0,
                st_blksize: 0,
                st_flags: 0,
                st_gen: 0,
                st_lspare: 0,
                st_qspare: [0, 0],
            }
        }
    }
}

#[cfg(target_os = "win32")]
mod stat {
    pub mod arch {
        use libc;
        pub fn default_stat() -> libc::stat {
            libc::stat {
                st_dev: 0,
                st_ino: 0,
                st_mode: 0,
                st_nlink: 0,
                st_uid: 0,
                st_gid: 0,
                st_rdev: 0,
                st_size: 0,
                st_atime: 0,
                st_mtime: 0,
                st_ctime: 0,
            }
        }
    }
}

#[cfg(target_os = "win32")]
impl WindowsPath {
    pub fn stat(&self) -> Option<libc::stat> {
        #[fixed_stack_segment]; #[inline(never)];
        do self.with_c_str |buf| {
            let mut st = stat::arch::default_stat();
            match unsafe { libc::stat(buf, &mut st) } {
                0 => Some(st),
                _ => None,
            }
        }
    }

    pub fn exists(&self) -> bool {
        match self.stat() {
            None => false,
            Some(_) => true,
        }
    }

    pub fn get_size(&self) -> Option<i64> {
        match self.stat() {
            None => None,
            Some(ref st) => Some(st.st_size as i64),
        }
    }

    pub fn get_mode(&self) -> Option<uint> {
        match self.stat() {
            None => None,
            Some(ref st) => Some(st.st_mode as uint),
        }
    }
}

#[cfg(not(target_os = "win32"))]
impl PosixPath {
    pub fn stat(&self) -> Option<libc::stat> {
        #[fixed_stack_segment]; #[inline(never)];
        do self.with_c_str |buf| {
            let mut st = stat::arch::default_stat();
            match unsafe { libc::stat(buf as *libc::c_char, &mut st) } {
                0 => Some(st),
                _ => None,
            }
        }
    }

    pub fn exists(&self) -> bool {
        match self.stat() {
            None => false,
            Some(_) => true,
        }
    }

    pub fn get_size(&self) -> Option<i64> {
        match self.stat() {
            None => None,
            Some(ref st) => Some(st.st_size as i64),
        }
    }

    pub fn get_mode(&self) -> Option<uint> {
        match self.stat() {
            None => None,
            Some(ref st) => Some(st.st_mode as uint),
        }
    }

    /// Executes a function `f` on `self` as well as on all of its ancestors.
    pub fn each_parent(&self, f: &fn(&Path)) {
        if !self.components.is_empty() {
            f(self);
            self.pop().each_parent(f);
        }
    }

}

#[cfg(target_os = "freebsd")]
#[cfg(target_os = "linux")]
#[cfg(target_os = "macos")]
impl PosixPath {
    pub fn get_atime(&self) -> Option<(i64, int)> {
        match self.stat() {
            None => None,
            Some(ref st) => {
                Some((st.st_atime as i64,
                      st.st_atime_nsec as int))
            }
        }
    }

    pub fn get_mtime(&self) -> Option<(i64, int)> {
        match self.stat() {
            None => None,
            Some(ref st) => {
                Some((st.st_mtime as i64,
                      st.st_mtime_nsec as int))
            }
        }
    }

    pub fn get_ctime(&self) -> Option<(i64, int)> {
        match self.stat() {
            None => None,
            Some(ref st) => {
                Some((st.st_ctime as i64,
                      st.st_ctime_nsec as int))
            }
        }
    }
}

#[cfg(unix)]
impl PosixPath {
    pub fn lstat(&self) -> Option<libc::stat> {
        #[fixed_stack_segment]; #[inline(never)];
        do self.with_c_str |buf| {
            let mut st = stat::arch::default_stat();
            match unsafe { libc::lstat(buf, &mut st) } {
                0 => Some(st),
                _ => None,
            }
        }
    }
}

#[cfg(target_os = "freebsd")]
#[cfg(target_os = "macos")]
impl PosixPath {
    pub fn get_birthtime(&self) -> Option<(i64, int)> {
        match self.stat() {
            None => None,
            Some(ref st) => {
                Some((st.st_birthtime as i64,
                      st.st_birthtime_nsec as int))
            }
        }
    }
}

#[cfg(target_os = "win32")]
impl WindowsPath {
    pub fn get_atime(&self) -> Option<(i64, int)> {
        match self.stat() {
            None => None,
            Some(ref st) => {
                Some((st.st_atime as i64, 0))
            }
        }
    }

    pub fn get_mtime(&self) -> Option<(i64, int)> {
        match self.stat() {
            None => None,
            Some(ref st) => {
                Some((st.st_mtime as i64, 0))
            }
        }
    }

    pub fn get_ctime(&self) -> Option<(i64, int)> {
        match self.stat() {
            None => None,
            Some(ref st) => {
                Some((st.st_ctime as i64, 0))
            }
        }
    }

    /// Executes a function `f` on `self` as well as on all of its ancestors.
    pub fn each_parent(&self, f: &fn(&Path)) {
        if !self.components.is_empty() {
            f(self);
            self.pop().each_parent(f);
        }
    }
}

impl ToStr for PosixPath {
    fn to_str(&self) -> ~str {
        let mut s = ~"";
        if self.is_absolute {
            s.push_str("/");
        }
        s + self.components.connect("/")
    }
}

impl ToCStr for PosixPath {
    fn to_c_str(&self) -> c_str::CString {
        self.to_str().to_c_str()
    }

    unsafe fn to_c_str_unchecked(&self) -> c_str::CString {
        self.to_str().to_c_str_unchecked()
    }
}

impl GenericPath for PosixPath {
    fn from_str(s: &str) -> PosixPath {
        let components = s.split_iter('/')
            .filter_map(|s| if s.is_empty() {None} else {Some(s.to_owned())})
            .collect();
        let is_absolute = (s.len() != 0 && s[0] == '/' as u8);
        PosixPath {
            is_absolute: is_absolute,
            components: components,
        }
    }

    fn with_dirname(&self, d: &str) -> PosixPath {
        let dpath = PosixPath(d);
        match self.filename() {
            Some(ref f) => dpath.push(*f),
            None => dpath,
        }
    }

    fn with_filename(&self, f: &str) -> PosixPath {
        assert!(!f.iter().all(posix::is_sep));
        self.dir_path().push(f)
    }

    fn file_path(&self) -> PosixPath {
        let cs = match self.filename() {
          None => ~[],
          Some(ref f) => ~[(*f).to_owned()]
        };
        PosixPath {
            is_absolute: false,
            components: cs,
        }
    }

    fn push(&self, s: &str) -> PosixPath {
        let mut v = self.components.clone();
        for s in s.split_iter(posix::is_sep) {
            if !s.is_empty() {
                v.push(s.to_owned())
            }
        }
        PosixPath {
            components: v,
            ..(*self).clone()
        }
    }

    fn push_many<S: Str>(&self, cs: &[S]) -> PosixPath {
        let mut v = self.components.clone();
        for e in cs.iter() {
            for s in e.as_slice().split_iter(posix::is_sep) {
                if !s.is_empty() {
                    v.push(s.to_owned())
                }
            }
        }
        PosixPath {
            is_absolute: self.is_absolute,
            components: v,
        }
    }

    fn pop(&self) -> PosixPath {
        let mut cs = self.components.clone();
        if cs.len() != 0 {
            cs.pop();
        }
        PosixPath {
            is_absolute: self.is_absolute,
            components: cs,
        } //..self }
    }

    fn unsafe_join(&self, other: &PosixPath) -> PosixPath {
        if other.is_absolute {
            PosixPath {
                is_absolute: true,
                components: other.components.clone(),
            }
        } else {
            self.push_rel(other)
        }
    }

    fn is_restricted(&self) -> bool {
        false
    }

    fn normalize(&self) -> PosixPath {
        PosixPath {
            is_absolute: self.is_absolute,
            components: normalize(self.components),
        } // ..self }
    }

    fn is_absolute(&self) -> bool {
        self.is_absolute
    }

    fn components<'a>(&'a self) -> &'a [~str] { self.components.as_slice() }

}


impl ToStr for WindowsPath {
    fn to_str(&self) -> ~str {
        let mut s = ~"";
        match self.host {
          Some(ref h) => {
            s.push_str("\\\\");
            s.push_str(*h);
          }
          None => { }
        }
        match self.device {
          Some(ref d) => {
            s.push_str(*d);
            s.push_str(":");
          }
          None => { }
        }
        if self.is_absolute {
            s.push_str("\\");
        }
        s + self.components.connect("\\")
    }
}

impl c_str::ToCStr for WindowsPath {
    fn to_c_str(&self) -> c_str::CString {
        self.to_str().to_c_str()
    }

    unsafe fn to_c_str_unchecked(&self) -> c_str::CString {
        self.to_str().to_c_str_unchecked()
    }
}

impl GenericPath for WindowsPath {
    fn from_str(s: &str) -> WindowsPath {
        let host;
        let device;
        let rest;

        match (
            windows::extract_drive_prefix(s),
            windows::extract_unc_prefix(s),
        ) {
            (Some((ref d, ref r)), _) => {
                host = None;
                device = Some((*d).clone());
                rest = (*r).clone();
            }
            (None, Some((ref h, ref r))) => {
                host = Some((*h).clone());
                device = None;
                rest = (*r).clone();
            }
            (None, None) => {
                host = None;
                device = None;
                rest = s.to_owned();
            }
        }

        let components = rest.split_iter(windows::is_sep)
            .filter_map(|s| if s.is_empty() {None} else {Some(s.to_owned())})
            .collect();

        let is_absolute = (rest.len() != 0 && windows::is_sep(rest[0] as char));
        WindowsPath {
            host: host,
            device: device,
            is_absolute: is_absolute,
            components: components,
        }
    }

    fn with_dirname(&self, d: &str) -> WindowsPath {
        let dpath = WindowsPath(d);
        match self.filename() {
            Some(ref f) => dpath.push(*f),
            None => dpath,
        }
    }

    fn with_filename(&self, f: &str) -> WindowsPath {
        assert!(! f.iter().all(windows::is_sep));
        self.dir_path().push(f)
    }

    fn file_path(&self) -> WindowsPath {
        WindowsPath {
            host: None,
            device: None,
            is_absolute: false,
            components: match self.filename() {
                None => ~[],
                Some(ref f) => ~[(*f).to_owned()],
            }
        }
    }

    fn push(&self, s: &str) -> WindowsPath {
        let mut v = self.components.clone();
        for s in s.split_iter(windows::is_sep) {
            if !s.is_empty() {
                v.push(s.to_owned())
            }
        }
        WindowsPath { components: v, ..(*self).clone() }
    }

    fn push_many<S: Str>(&self, cs: &[S]) -> WindowsPath {
        let mut v = self.components.clone();
        for e in cs.iter() {
            for s in e.as_slice().split_iter(windows::is_sep) {
                if !s.is_empty() {
                    v.push(s.to_owned())
                }
            }
        }
        // tedious, but as-is, we can't use ..self
        WindowsPath {
            host: self.host.clone(),
            device: self.device.clone(),
            is_absolute: self.is_absolute,
            components: v
        }
    }

    fn pop(&self) -> WindowsPath {
        let mut cs = self.components.clone();
        if cs.len() != 0 {
            cs.pop();
        }
        WindowsPath {
            host: self.host.clone(),
            device: self.device.clone(),
            is_absolute: self.is_absolute,
            components: cs,
        }
    }

    fn unsafe_join(&self, other: &WindowsPath) -> WindowsPath {
        /* rhs not absolute is simple push */
        if !other.is_absolute {
            return self.push_many(other.components);
        }

        /* if rhs has a host set, then the whole thing wins */
        match other.host {
            Some(ref host) => {
                return WindowsPath {
                    host: Some((*host).clone()),
                    device: other.device.clone(),
                    is_absolute: true,
                    components: other.components.clone(),
                };
            }
            _ => {}
        }

        /* if rhs has a device set, then a part wins */
        match other.device {
            Some(ref device) => {
                return WindowsPath {
                    host: None,
                    device: Some((*device).clone()),
                    is_absolute: true,
                    components: other.components.clone(),
                };
            }
            _ => {}
        }

        /* fallback: host and device of lhs win, but the
           whole path of the right */
        WindowsPath {
            host: self.host.clone(),
            device: self.device.clone(),
            is_absolute: self.is_absolute || other.is_absolute,
            components: other.components.clone(),
        }
    }

    fn is_restricted(&self) -> bool {
        match self.filestem() {
            Some(stem) => {
                // FIXME: #4318 Instead of to_ascii and to_str_ascii, could use
                // to_ascii_move and to_str_move to not do a unnecessary copy.
                match stem.to_ascii().to_lower().to_str_ascii() {
                    ~"con" | ~"aux" | ~"com1" | ~"com2" | ~"com3" | ~"com4" |
                    ~"lpt1" | ~"lpt2" | ~"lpt3" | ~"prn" | ~"nul" => true,
                    _ => false
                }
            },
            None => false
        }
    }

    fn normalize(&self) -> WindowsPath {
        WindowsPath {
            host: self.host.clone(),
            device: match self.device {
                None => None,

                // FIXME: #4318 Instead of to_ascii and to_str_ascii, could use
                // to_ascii_move and to_str_move to not do a unnecessary copy.
                Some(ref device) => Some(device.to_ascii().to_upper().to_str_ascii())
            },
            is_absolute: self.is_absolute,
            components: normalize(self.components)
        }
    }

    fn is_absolute(&self) -> bool {
        self.is_absolute
    }

    fn components<'a>(&'a self) -> &'a [~str] { self.components.as_slice() }

}

pub fn normalize(components: &[~str]) -> ~[~str] {
    let mut cs = ~[];
    for c in components.iter() {
        if *c == ~"." && components.len() > 1 { loop; }
        if *c == ~"" { loop; }
        if *c == ~".." && cs.len() != 0 {
            cs.pop();
            loop;
        }
        cs.push((*c).clone());
    }
    cs
}

// Various posix helpers.
pub mod posix {

    #[inline]
    pub fn is_sep(u: char) -> bool {
        u == '/'
    }

}

// Various windows helpers.
pub mod windows {
    use libc;
    use option::{None, Option, Some};

    #[inline]
    pub fn is_sep(u: char) -> bool {
        u == '/' || u == '\\'
    }

    pub fn extract_unc_prefix(s: &str) -> Option<(~str,~str)> {
        if (s.len() > 1 &&
            (s[0] == '\\' as u8 || s[0] == '/' as u8) &&
            s[0] == s[1]) {
            let mut i = 2;
            while i < s.len() {
                if is_sep(s[i] as char) {
                    let pre = s.slice(2, i).to_owned();
                    let rest = s.slice(i, s.len()).to_owned();
                    return Some((pre, rest));
                }
                i += 1;
            }
        }
        None
    }

    pub fn extract_drive_prefix(s: &str) -> Option<(~str,~str)> {
        #[fixed_stack_segment]; #[inline(never)];

        unsafe {
            if (s.len() > 1 &&
                libc::isalpha(s[0] as libc::c_int) != 0 &&
                s[1] == ':' as u8) {
                let rest = if s.len() == 2 {
                    ~""
                } else {
                    s.slice(2, s.len()).to_owned()
                };
                return Some((s.slice(0,1).to_owned(), rest));
            }
            None
        }
    }
}

#[cfg(test)]
mod tests {
    use option::{None, Some};
    use path::{PosixPath, WindowsPath, windows};

    #[test]
    fn test_double_slash_collapsing() {
        let path = PosixPath("tmp/");
        let path = path.push("/hmm");
        let path = path.normalize();
        assert_eq!(~"tmp/hmm", path.to_str());

        let path = WindowsPath("tmp/");
        let path = path.push("/hmm");
        let path = path.normalize();
        assert_eq!(~"tmp\\hmm", path.to_str());
    }

    #[test]
    fn test_filetype_foo_bar() {
        let wp = PosixPath("foo.bar");
        assert_eq!(wp.filetype(), Some(".bar"));

        let wp = WindowsPath("foo.bar");
        assert_eq!(wp.filetype(), Some(".bar"));
    }

    #[test]
    fn test_filetype_foo() {
        let wp = PosixPath("foo");
        assert_eq!(wp.filetype(), None);

        let wp = WindowsPath("foo");
        assert_eq!(wp.filetype(), None);
    }

    #[test]
    fn test_posix_paths() {
        fn t(wp: &PosixPath, s: &str) {
            let ss = wp.to_str();
            let sss = s.to_owned();
            if (ss != sss) {
                debug!("got %s", ss);
                debug!("expected %s", sss);
                assert_eq!(ss, sss);
            }
        }

        t(&(PosixPath("hi")), "hi");
        t(&(PosixPath("/lib")), "/lib");
        t(&(PosixPath("hi/there")), "hi/there");
        t(&(PosixPath("hi/there.txt")), "hi/there.txt");

        t(&(PosixPath("hi/there.txt")), "hi/there.txt");
        t(&(PosixPath("hi/there.txt")
           .with_filetype("")), "hi/there");

        t(&(PosixPath("/a/b/c/there.txt")
            .with_dirname("hi")), "hi/there.txt");

        t(&(PosixPath("hi/there.txt")
            .with_dirname(".")), "./there.txt");

        t(&(PosixPath("a/b/c")
            .push("..")), "a/b/c/..");

        t(&(PosixPath("there.txt")
            .with_filetype("o")), "there.o");

        t(&(PosixPath("hi/there.txt")
            .with_filetype("o")), "hi/there.o");

        t(&(PosixPath("hi/there.txt")
            .with_filetype("o")
            .with_dirname("/usr/lib")),
          "/usr/lib/there.o");

        t(&(PosixPath("hi/there.txt")
            .with_filetype("o")
            .with_dirname("/usr/lib/")),
          "/usr/lib/there.o");

        t(&(PosixPath("hi/there.txt")
            .with_filetype("o")
            .with_dirname("/usr//lib//")),
            "/usr/lib/there.o");

        t(&(PosixPath("/usr/bin/rust")
            .push_many([~"lib", ~"thingy.so"])
            .with_filestem("librustc")),
          "/usr/bin/rust/lib/librustc.so");

    }

    #[test]
    fn test_posix_push_with_backslash() {
        let a = PosixPath("/aaa/bbb");
        let b = a.push("x\\y"); // \ is not a file separator for posix paths
        assert_eq!(a.components.len(), 2);
        assert_eq!(b.components.len(), 3);
    }

    #[test]
    fn test_normalize() {
        fn t(wp: &PosixPath, s: &str) {
            let ss = wp.to_str();
            let sss = s.to_owned();
            if (ss != sss) {
                debug!("got %s", ss);
                debug!("expected %s", sss);
                assert_eq!(ss, sss);
            }
        }

        t(&(PosixPath("hi/there.txt")
            .with_dirname(".").normalize()), "there.txt");

        t(&(PosixPath("a/b/../c/././/../foo.txt/").normalize()),
          "a/foo.txt");

        t(&(PosixPath("a/b/c")
            .push("..").normalize()), "a/b");
    }

    #[test]
    fn test_extract_unc_prefixes() {
        assert!(windows::extract_unc_prefix("\\\\").is_none());
        assert!(windows::extract_unc_prefix("//").is_none());
        assert!(windows::extract_unc_prefix("\\\\hi").is_none());
        assert!(windows::extract_unc_prefix("//hi").is_none());
        assert!(windows::extract_unc_prefix("\\\\hi\\") ==
            Some((~"hi", ~"\\")));
        assert!(windows::extract_unc_prefix("//hi\\") ==
            Some((~"hi", ~"\\")));
        assert!(windows::extract_unc_prefix("\\\\hi\\there") ==
            Some((~"hi", ~"\\there")));
        assert!(windows::extract_unc_prefix("//hi/there") ==
            Some((~"hi", ~"/there")));
        assert!(windows::extract_unc_prefix(
            "\\\\hi\\there\\friends.txt") ==
            Some((~"hi", ~"\\there\\friends.txt")));
        assert!(windows::extract_unc_prefix(
            "//hi\\there\\friends.txt") ==
            Some((~"hi", ~"\\there\\friends.txt")));
    }

    #[test]
    fn test_extract_drive_prefixes() {
        assert!(windows::extract_drive_prefix("c").is_none());
        assert!(windows::extract_drive_prefix("c:") ==
                     Some((~"c", ~"")));
        assert!(windows::extract_drive_prefix("d:") ==
                     Some((~"d", ~"")));
        assert!(windows::extract_drive_prefix("z:") ==
                     Some((~"z", ~"")));
        assert!(windows::extract_drive_prefix("c:\\hi") ==
                     Some((~"c", ~"\\hi")));
        assert!(windows::extract_drive_prefix("d:hi") ==
                     Some((~"d", ~"hi")));
        assert!(windows::extract_drive_prefix("c:hi\\there.txt") ==
                     Some((~"c", ~"hi\\there.txt")));
        assert!(windows::extract_drive_prefix("c:\\hi\\there.txt") ==
                     Some((~"c", ~"\\hi\\there.txt")));
    }

    #[test]
    fn test_windows_paths() {
        fn t(wp: &WindowsPath, s: &str) {
            let ss = wp.to_str();
            let sss = s.to_owned();
            if (ss != sss) {
                debug!("got %s", ss);
                debug!("expected %s", sss);
                assert_eq!(ss, sss);
            }
        }

        t(&(WindowsPath("hi")), "hi");
        t(&(WindowsPath("hi/there")), "hi\\there");
        t(&(WindowsPath("hi/there.txt")), "hi\\there.txt");

        t(&(WindowsPath("there.txt")
            .with_filetype("o")), "there.o");

        t(&(WindowsPath("hi/there.txt")
            .with_filetype("o")), "hi\\there.o");

        t(&(WindowsPath("hi/there.txt")
            .with_filetype("o")
            .with_dirname("c:\\program files A")),
          "c:\\program files A\\there.o");

        t(&(WindowsPath("hi/there.txt")
            .with_filetype("o")
            .with_dirname("c:\\program files B\\")),
          "c:\\program files B\\there.o");

        t(&(WindowsPath("hi/there.txt")
            .with_filetype("o")
            .with_dirname("c:\\program files C\\/")),
            "c:\\program files C\\there.o");

        t(&(WindowsPath("c:\\program files (x86)\\rust")
            .push_many([~"lib", ~"thingy.dll"])
            .with_filename("librustc.dll")),
          "c:\\program files (x86)\\rust\\lib\\librustc.dll");

        t(&(WindowsPath("\\\\computer\\share")
            .unsafe_join(&WindowsPath("\\a"))),
          "\\\\computer\\a");

        t(&(WindowsPath("//computer/share")
            .unsafe_join(&WindowsPath("\\a"))),
          "\\\\computer\\a");

        t(&(WindowsPath("//computer/share")
            .unsafe_join(&WindowsPath("\\\\computer\\share"))),
          "\\\\computer\\share");

        t(&(WindowsPath("C:/whatever")
            .unsafe_join(&WindowsPath("//computer/share/a/b"))),
          "\\\\computer\\share\\a\\b");

        t(&(WindowsPath("C:")
            .unsafe_join(&WindowsPath("D:/foo"))),
          "D:\\foo");

        t(&(WindowsPath("C:")
            .unsafe_join(&WindowsPath("B"))),
          "C:B");

        t(&(WindowsPath("C:")
            .unsafe_join(&WindowsPath("/foo"))),
          "C:\\foo");

        t(&(WindowsPath("C:\\")
            .unsafe_join(&WindowsPath("\\bar"))),
          "C:\\bar");

        t(&(WindowsPath("")
            .unsafe_join(&WindowsPath(""))),
          "");

        t(&(WindowsPath("")
            .unsafe_join(&WindowsPath("a"))),
          "a");

        t(&(WindowsPath("")
            .unsafe_join(&WindowsPath("C:\\a"))),
          "C:\\a");

        t(&(WindowsPath("c:\\foo")
            .normalize()),
          "C:\\foo");
    }

    #[test]
    fn test_windows_path_restrictions() {
        assert_eq!(WindowsPath("hi").is_restricted(), false);
        assert_eq!(WindowsPath("C:\\NUL").is_restricted(), true);
        assert_eq!(WindowsPath("C:\\COM1.TXT").is_restricted(), true);
        assert_eq!(WindowsPath("c:\\prn.exe").is_restricted(), true);
    }

    #[test]
    fn test_is_ancestor_of() {
        assert!(&PosixPath("/a/b").is_ancestor_of(&PosixPath("/a/b/c/d")));
        assert!(!&PosixPath("/a/b/c/d").is_ancestor_of(&PosixPath("/a/b")));
        assert!(!&PosixPath("/a/b").is_ancestor_of(&PosixPath("/c/d")));
        assert!(&PosixPath("/a/b").is_ancestor_of(&PosixPath("/a/b/c/d")));
        assert!(&PosixPath("/").is_ancestor_of(&PosixPath("/a/b/c")));
        assert!(!&PosixPath("/").is_ancestor_of(&PosixPath("")));
        assert!(!&PosixPath("/a/b/c").is_ancestor_of(&PosixPath("")));
        assert!(!&PosixPath("").is_ancestor_of(&PosixPath("/a/b/c")));

        assert!(&WindowsPath("C:\\a\\b").is_ancestor_of(&WindowsPath("C:\\a\\b\\c\\d")));
        assert!(!&WindowsPath("C:\\a\\b\\c\\d").is_ancestor_of(&WindowsPath("C:\\a\\b")));
        assert!(!&WindowsPath("C:\\a\\b").is_ancestor_of(&WindowsPath("C:\\c\\d")));
        assert!(&WindowsPath("C:\\a\\b").is_ancestor_of(&WindowsPath("C:\\a\\b\\c\\d")));
        assert!(&WindowsPath("C:\\").is_ancestor_of(&WindowsPath("C:\\a\\b\\c")));
        assert!(!&WindowsPath("C:\\").is_ancestor_of(&WindowsPath("")));
        assert!(!&WindowsPath("C:\\a\\b\\c").is_ancestor_of(&WindowsPath("")));
        assert!(!&WindowsPath("").is_ancestor_of(&WindowsPath("C:\\a\\b\\c")));

    }

    #[test]
    fn test_relative_to1() {
        let p1 = PosixPath("/usr/bin/rustc");
        let p2 = PosixPath("/usr/lib/mylib");
        let res = p1.get_relative_to(&p2);
        assert_eq!(res, PosixPath("../lib"));

        let p1 = WindowsPath("C:\\usr\\bin\\rustc");
        let p2 = WindowsPath("C:\\usr\\lib\\mylib");
        let res = p1.get_relative_to(&p2);
        assert_eq!(res, WindowsPath("..\\lib"));

    }

    #[test]
    fn test_relative_to2() {
        let p1 = PosixPath("/usr/bin/rustc");
        let p2 = PosixPath("/usr/bin/../lib/mylib");
        let res = p1.get_relative_to(&p2);
        assert_eq!(res, PosixPath("../lib"));

        let p1 = WindowsPath("C:\\usr\\bin\\rustc");
        let p2 = WindowsPath("C:\\usr\\bin\\..\\lib\\mylib");
        let res = p1.get_relative_to(&p2);
        assert_eq!(res, WindowsPath("..\\lib"));
    }

    #[test]
    fn test_relative_to3() {
        let p1 = PosixPath("/usr/bin/whatever/rustc");
        let p2 = PosixPath("/usr/lib/whatever/mylib");
        let res = p1.get_relative_to(&p2);
        assert_eq!(res, PosixPath("../../lib/whatever"));

        let p1 = WindowsPath("C:\\usr\\bin\\whatever\\rustc");
        let p2 = WindowsPath("C:\\usr\\lib\\whatever\\mylib");
        let res = p1.get_relative_to(&p2);
        assert_eq!(res, WindowsPath("..\\..\\lib\\whatever"));

    }

    #[test]
    fn test_relative_to4() {
        let p1 = PosixPath("/usr/bin/whatever/../rustc");
        let p2 = PosixPath("/usr/lib/whatever/mylib");
        let res = p1.get_relative_to(&p2);
        assert_eq!(res, PosixPath("../lib/whatever"));

        let p1 = WindowsPath("C:\\usr\\bin\\whatever\\..\\rustc");
        let p2 = WindowsPath("C:\\usr\\lib\\whatever\\mylib");
        let res = p1.get_relative_to(&p2);
        assert_eq!(res, WindowsPath("..\\lib\\whatever"));

    }

    #[test]
    fn test_relative_to5() {
        let p1 = PosixPath("/usr/bin/whatever/../rustc");
        let p2 = PosixPath("/usr/lib/whatever/../mylib");
        let res = p1.get_relative_to(&p2);
        assert_eq!(res, PosixPath("../lib"));

        let p1 = WindowsPath("C:\\usr\\bin/whatever\\..\\rustc");
        let p2 = WindowsPath("C:\\usr\\lib\\whatever\\..\\mylib");
        let res = p1.get_relative_to(&p2);
        assert_eq!(res, WindowsPath("..\\lib"));
    }

    #[test]
    fn test_relative_to6() {
        let p1 = PosixPath("/1");
        let p2 = PosixPath("/2/3");
        let res = p1.get_relative_to(&p2);
        assert_eq!(res, PosixPath("2"));

        let p1 = WindowsPath("C:\\1");
        let p2 = WindowsPath("C:\\2\\3");
        let res = p1.get_relative_to(&p2);
        assert_eq!(res, WindowsPath("2"));

    }

    #[test]
    fn test_relative_to7() {
        let p1 = PosixPath("/1/2");
        let p2 = PosixPath("/3");
        let res = p1.get_relative_to(&p2);
        assert_eq!(res, PosixPath(".."));

        let p1 = WindowsPath("C:\\1\\2");
        let p2 = WindowsPath("C:\\3");
        let res = p1.get_relative_to(&p2);
        assert_eq!(res, WindowsPath(".."));

    }

    #[test]
    fn test_relative_to8() {
        let p1 = PosixPath("/home/brian/Dev/rust/build/").push_rel(
            &PosixPath("stage2/lib/rustc/i686-unknown-linux-gnu/lib/librustc.so"));
        let p2 = PosixPath("/home/brian/Dev/rust/build/stage2/bin/..").push_rel(
            &PosixPath("lib/rustc/i686-unknown-linux-gnu/lib/libstd.so"));
        let res = p1.get_relative_to(&p2);
        debug!("test_relative_to8: %s vs. %s",
               res.to_str(),
               PosixPath(".").to_str());
        assert_eq!(res, PosixPath("."));

        let p1 = WindowsPath("C:\\home\\brian\\Dev\\rust\\build\\").push_rel(
            &WindowsPath("stage2\\lib\\rustc\\i686-unknown-linux-gnu\\lib\\librustc.so"));
        let p2 = WindowsPath("\\home\\brian\\Dev\\rust\\build\\stage2\\bin\\..").push_rel(
            &WindowsPath("lib\\rustc\\i686-unknown-linux-gnu\\lib\\libstd.so"));
        let res = p1.get_relative_to(&p2);
        debug!("test_relative_to8: %s vs. %s",
               res.to_str(),
               WindowsPath(".").to_str());
        assert_eq!(res, WindowsPath("."));

    }


    #[test]
    fn test_is_parent_of() {
        assert!(is_parent_of(&PosixPath("/a/b/c/d/e"), &PosixPath("c/d/e")));
        assert!(!is_parent_of(&PosixPath("a/b/c/d/e"), &PosixPath("c/d/e")));
        assert!(!is_parent_of(&PosixPath("/a/b/c/d/e"), &PosixPath("/c/d/e")));
        assert!(!is_parent_of(&PosixPath(""), &PosixPath("")));
        assert!(!is_parent_of(&PosixPath(""), &PosixPath("a/b/c")));
        assert!(is_parent_of(&PosixPath("/a/b/c"), &PosixPath("")));
        assert!(is_parent_of(&PosixPath("/a/b/c"), &PosixPath("a/b/c")));
        assert!(!is_parent_of(&PosixPath("/a/b/c"), &PosixPath("d/e/f")));

        let abcde = WindowsPath("C:\\a\\b\\c\\d\\e");
        let rel_abcde = WindowsPath("a\\b\\c\\d\\e");
        let cde   = WindowsPath("c\\d\\e");
        let slashcde = WindowsPath("C:\\c\\d\\e");
        let empty = WindowsPath("");
        let abc = WindowsPath("C:\\a\\b\\c");
        let rel_abc = WindowsPath("a\\b\\c");
        let def = WindowsPath("d\\e\\f");

        assert!(is_parent_of(&abcde, &cde));
        assert!(!is_parent_of(&rel_abcde, &cde));
        assert!(!is_parent_of(&abcde, &slashcde));
        assert!(!is_parent_of(&empty, &empty));
        assert!(is_parent_of(&abc, &empty);
        assert!(is_parent_of(&abc, &rel_abc));
        assert!(!is_parent_of(&abc, &def));
    }

}