feat(path): File type predicates

Part of assert-rs#8.

src/predicate/path/ft.rs

@@ -0,0 +1,125 @@
+// Copyright (c) 2018 The predicates-rs Project 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.
+
+use std::path;
+use std::fs;
+
+use Predicate;
+
+#[derive(Clone, Copy, Debug)]
+enum FileType {
+    File,
+    Dir,
+    Symlink,
+}
+
+impl FileType {
+    fn eval(self, ft: &fs::FileType) -> bool {
+        match self {
+            FileType::File => ft.is_file(),
+            FileType::Dir => ft.is_dir(),
+            FileType::Symlink => ft.is_symlink(),
+        }
+    }
+}
+
+/// Predicate that checks the `std::fs::FileType`.
+///
+/// This is created by the `predicate::path::is_file`, `predicate::path::is_dir`, and `predicate::path::is_symlink`.
+#[derive(Debug)]
+pub struct FileTypePredicate {
+    ft: FileType,
+    follow: bool,
+}
+
+impl FileTypePredicate {
+    /// Follow symbolic links.
+    ///
+    /// When yes is true, symbolic links are followed as if they were normal directories and files.
+    ///
+    /// Default: disabled.
+    pub fn follow_links(mut self, yes: bool) -> Self {
+        self.follow = yes;
+        self
+    }
+}
+
+impl Predicate for FileTypePredicate {
+    type Item = path::Path;
+
+    fn eval(&self, path: &path::Path) -> bool {
+        let metadata = if self.follow {
+            path.metadata()
+        } else {
+            path.symlink_metadata()
+        };
+        metadata
+            .map(|m| self.ft.eval(&m.file_type()))
+            .unwrap_or(false)
+    }
+}
+
+/// Creates a new `Predicate` that ensures the path points to a file.
+///
+/// # Examples
+///
+/// ```
+/// use std::path::Path;
+/// use predicates::predicate::*;
+///
+/// let predicate_fn = path::is_file();
+/// assert_eq!(true, predicate_fn.eval(Path::new("Cargo.toml")));
+/// assert_eq!(false, predicate_fn.eval(Path::new("src")));
+/// assert_eq!(false, predicate_fn.eval(Path::new("non-existent-file.foo")));
+/// ```
+pub fn is_file() -> FileTypePredicate {
+    FileTypePredicate {
+        ft: FileType::File,
+        follow: false,
+    }
+}
+
+/// Creates a new `Predicate` that ensures the path points to a directory.
+///
+/// # Examples
+///
+/// ```
+/// use std::path::Path;
+/// use predicates::predicate::*;
+///
+/// let predicate_fn = path::is_dir();
+/// assert_eq!(false, predicate_fn.eval(Path::new("Cargo.toml")));
+/// assert_eq!(true, predicate_fn.eval(Path::new("src")));
+/// assert_eq!(false, predicate_fn.eval(Path::new("non-existent-file.foo")));
+/// ```
+pub fn is_dir() -> FileTypePredicate {
+    FileTypePredicate {
+        ft: FileType::Dir,
+        follow: false,
+    }
+}
+
+/// Creates a new `Predicate` that ensures the path points to a symlink.
+///
+/// # Examples
+///
+/// ```
+/// use std::path::Path;
+/// use predicates::predicate::*;
+///
+/// let predicate_fn = path::is_symlink();
+/// assert_eq!(false, predicate_fn.eval(Path::new("Cargo.toml")));
+/// assert_eq!(false, predicate_fn.eval(Path::new("src")));
+/// assert_eq!(false, predicate_fn.eval(Path::new("non-existent-file.foo")));
+/// ```
+pub fn is_symlink() -> FileTypePredicate {
+    FileTypePredicate {
+        ft: FileType::Symlink,
+        follow: false,
+    }
+}

src/predicate/path/mod.rs

@@ -12,3 +12,5 @@
 
 mod existence;
 pub use self::existence::{exists, missing, ExistencePredicate};
+mod ft;
+pub use self::ft::{is_dir, is_file, is_symlink, FileTypePredicate};