path: root/src/walk.rs

use std::cmp;
use std::fmt;
use std::path::{Path, PathBuf};
use std::result;
use std::usize;

use crate::dent::DirEntry;
use crate::error::Result;

struct WalkDirOptions {
    follow_links: bool,
    max_open: usize,
    min_depth: usize,
    max_depth: usize,
    sorter: Option<
        Box<
            FnMut(&DirEntry, &DirEntry) -> cmp::Ordering
                + Send
                + Sync
                + 'static,
        >,
    >,
    contents_first: bool,
    same_file_system: bool,
}

impl fmt::Debug for WalkDirOptions {
    fn fmt(&self, f: &mut fmt::Formatter) -> result::Result<(), fmt::Error> {
        let sorter_str = if self.sorter.is_some() {
            // FnMut isn't `Debug`
            "Some(...)"
        } else {
            "None"
        };
        f.debug_struct("WalkDirOptions")
            .field("follow_links", &self.follow_links)
            .field("max_open", &self.max_open)
            .field("min_depth", &self.min_depth)
            .field("max_depth", &self.max_depth)
            .field("sorter", &sorter_str)
            .field("contents_first", &self.contents_first)
            .field("same_file_system", &self.same_file_system)
            .finish()
    }
}

/// TODO
#[derive(Debug)]
pub struct WalkDir {
    root: PathBuf,
    opts: WalkDirOptions,
}

impl IntoIterator for WalkDir {
    type Item = Result<DirEntry>;
    type IntoIter = IntoIter;

    fn into_iter(self) -> IntoIter {
        unimplemented!()
    }
}

impl WalkDir {
    /// Create a builder for a recursive directory iterator starting at the
    /// file path `root`. If `root` is a directory, then it is the first item
    /// yielded by the iterator. If `root` is a file, then it is the first
    /// and only item yielded by the iterator. If `root` is a symlink, then it
    /// is always followed for the purposes of directory traversal. (A root
    /// `DirEntry` still obeys its documentation with respect to symlinks and
    /// the `follow_links` setting.)
    pub fn new<P: Into<PathBuf>>(root: P) -> WalkDir {
        WalkDir {
            root: root.into(),
            opts: WalkDirOptions {
                follow_links: false,
                max_open: 10,
                min_depth: 0,
                max_depth: usize::MAX,
                sorter: None,
                contents_first: false,
                same_file_system: false,
            },
        }
    }

    /// Set the minimum depth of entries yielded by the iterator.
    ///
    /// The smallest depth is `0` and always corresponds to the path given
    /// to the `new` function on this type. Its direct descendents have depth
    /// `1`, and their descendents have depth `2`, and so on.
    pub fn min_depth(mut self, depth: usize) -> WalkDir {
        self.opts.min_depth = depth;
        if self.opts.min_depth > self.opts.max_depth {
            self.opts.min_depth = self.opts.max_depth;
        }
        self
    }

    /// Set the maximum depth of entries yield by the iterator.
    ///
    /// The smallest depth is `0` and always corresponds to the path given
    /// to the `new` function on this type. Its direct descendents have depth
    /// `1`, and their descendents have depth `2`, and so on.
    ///
    /// Note that this will not simply filter the entries of the iterator, but
    /// it will actually avoid descending into directories when the depth is
    /// exceeded.
    pub fn max_depth(mut self, depth: usize) -> WalkDir {
        self.opts.max_depth = depth;
        if self.opts.max_depth < self.opts.min_depth {
            self.opts.max_depth = self.opts.min_depth;
        }
        self
    }

    /// Follow symbolic links. By default, this is disabled.
    ///
    /// When `yes` is `true`, symbolic links are followed as if they were
    /// normal directories and files. If a symbolic link is broken or is
    /// involved in a loop, an error is yielded.
    ///
    /// When enabled, the yielded [`DirEntry`] values represent the target of
    /// the link while the path corresponds to the link. See the [`DirEntry`]
    /// type for more details.
    ///
    /// [`DirEntry`]: struct.DirEntry.html
    pub fn follow_links(mut self, yes: bool) -> WalkDir {
        self.opts.follow_links = yes;
        self
    }

    /// Set the maximum number of simultaneously open file descriptors used
    /// by the iterator.
    ///
    /// `n` must be greater than or equal to `1`. If `n` is `0`, then it is set
    /// to `1` automatically. If this is not set, then it defaults to some
    /// reasonably low number.
    ///
    /// This setting has no impact on the results yielded by the iterator
    /// (even when `n` is `1`). Instead, this setting represents a trade off
    /// between scarce resources (file descriptors) and memory. Namely, when
    /// the maximum number of file descriptors is reached and a new directory
    /// needs to be opened to continue iteration, then a previous directory
    /// handle is closed and has its unyielded entries stored in memory. In
    /// practice, this is a satisfying trade off because it scales with respect
    /// to the *depth* of your file tree. Therefore, low values (even `1`) are
    /// acceptable.
    ///
    /// Note that this value does not impact the number of system calls made by
    /// an exhausted iterator.
    ///
    /// # Platform behavior
    ///
    /// On Windows, if `follow_links` is enabled, then this limit is not
    /// respected. In particular, the maximum number of file descriptors opened
    /// is proportional to the depth of the directory tree traversed.
    pub fn max_open(mut self, mut n: usize) -> WalkDir {
        if n == 0 {
            n = 1;
        }
        self.opts.max_open = n;
        self
    }

    /// Set a function for sorting directory entries.
    ///
    /// If a compare function is set, the resulting iterator will return all
    /// paths in sorted order. The compare function will be called to compare
    /// entries from the same directory.
    ///
    /// ```rust,no-run
    /// use std::cmp;
    /// use std::ffi::OsString;
    /// use walkdir::WalkDir;
    ///
    /// WalkDir::new("foo").sort_by(|a,b| a.file_name().cmp(b.file_name()));
    /// ```
    pub fn sort_by<F>(mut self, cmp: F) -> WalkDir
    where
        F: FnMut(&DirEntry, &DirEntry) -> cmp::Ordering
            + Send
            + Sync
            + 'static,
    {
        self.opts.sorter = Some(Box::new(cmp));
        self
    }

    /// Yield a directory's contents before the directory itself. By default,
    /// this is disabled.
    ///
    /// When `yes` is `false` (as is the default), the directory is yielded
    /// before its contents are read. This is useful when, e.g. you want to
    /// skip processing of some directories.
    ///
    /// When `yes` is `true`, the iterator yields the contents of a directory
    /// before yielding the directory itself. This is useful when, e.g. you
    /// want to recursively delete a directory.
    ///
    /// # Example
    ///
    /// Assume the following directory tree:
    ///
    /// ```text
    /// foo/
    ///   abc/
    ///     qrs
    ///     tuv
    ///   def/
    /// ```
    ///
    /// With contents_first disabled (the default), the following code visits
    /// the directory tree in depth-first order:
    ///
    /// ```no_run
    /// use walkdir::WalkDir;
    ///
    /// for entry in WalkDir::new("foo") {
    ///     let entry = entry.unwrap();
    ///     println!("{}", entry.path().display());
    /// }
    ///
    /// // foo
    /// // foo/abc
    /// // foo/abc/qrs
    /// // foo/abc/tuv
    /// // foo/def
    /// ```
    ///
    /// With contents_first enabled:
    ///
    /// ```no_run
    /// use walkdir::WalkDir;
    ///
    /// for entry in WalkDir::new("foo").contents_first(true) {
    ///     let entry = entry.unwrap();
    ///     println!("{}", entry.path().display());
    /// }
    ///
    /// // foo/abc/qrs
    /// // foo/abc/tuv
    /// // foo/abc
    /// // foo/def
    /// // foo
    /// ```
    pub fn contents_first(mut self, yes: bool) -> WalkDir {
        self.opts.contents_first = yes;
        self
    }

    /// Do not cross file system boundaries.
    ///
    /// When this option is enabled, directory traversal will not descend into
    /// directories that are on a different file system from the root path.
    ///
    /// Currently, this option is only supported on Unix and Windows. If this
    /// option is used on an unsupported platform, then directory traversal
    /// will immediately return an error and will not yield any entries.
    pub fn same_file_system(mut self, yes: bool) -> WalkDir {
        self.opts.same_file_system = yes;
        self
    }
}

#[derive(Debug)]
struct Walker {
    root: PathBuf,
    depth: usize,
    opts: WalkDirOptions,
}

impl Walker {
    fn new() -> Walker {
        Walker {
            root: PathBuf::new(),
            depth: 0,
            opts: WalkDirOptions {
                follow_links: false,
                max_open: 10,
                min_depth: 0,
                max_depth: usize::MAX,
                sorter: None,
                contents_first: false,
                same_file_system: false,
            },
        }
    }
}

/// TODO
#[derive(Debug)]
pub struct IntoIter {}

impl Iterator for IntoIter {
    type Item = Result<DirEntry>;

    fn next(&mut self) -> Option<Result<DirEntry>> {
        unimplemented!()
    }
}

impl IntoIter {
    /// TODO
    pub fn filter_entry<P>(self, predicate: P) -> FilterEntry<Self, P>
    where
        P: FnMut(&DirEntry) -> bool,
    {
        FilterEntry { it: self, predicate: predicate }
    }

    /// TODO
    pub fn skip_current_dir(&mut self) {
        unimplemented!()
    }
}

/// TODO
#[derive(Debug)]
pub struct FilterEntry<I, P> {
    it: I,
    predicate: P,
}

impl<P> Iterator for FilterEntry<IntoIter, P>
where
    P: FnMut(&DirEntry) -> bool,
{
    type Item = Result<DirEntry>;

    /// Advances the iterator and returns the next value.
    ///
    /// # Errors
    ///
    /// If the iterator fails to retrieve the next value, this method returns
    /// an error value. The error will be wrapped in an `Option::Some`.
    fn next(&mut self) -> Option<Result<DirEntry>> {
        unimplemented!()
    }
}