sketch filesystem context, without probing for now (#301)

Author: Byron

git-worktree/src/lib.rs

@@ -1,3 +1,61 @@
 #![forbid(unsafe_code, rust_2018_idioms)]
 
+/// file system related utilities
+pub mod fs {
+    /// Common knowledge about the worktree that is needed across most interactions with the work tree
+    pub struct Context {
+        /// If true, the filesystem will store paths as decomposed unicode, i.e. `ä` becomes `"a\u{308}"`, which means that
+        /// we have to turn these forms back from decomposed to precomposed unicode before storing it in the index or generally
+        /// using it. This also applies to input received from the command-line, so callers may have to be aware of this and
+        /// perform conversions accordingly.
+        /// If false, no conversions will be performed.
+        pub precompose_unicode: bool,
+        /// If true, the filesystem ignores the case of input, which makes `A` the same file as `a`.
+        /// This is also called case-folding.
+        pub ignore_case: bool,
+        /// If true, we assume the the executable bit is honored as part of the files mode. If false, we assume the file system
+        /// ignores the executable bit, hence it will be reported as 'off' even though we just tried to set it to be on.
+        pub file_mode: bool,
+        /// If true, the file system supports symbolic links and we should try to create them. Otherwise symbolic links will be checked
+        /// out as files which contain the link as text.
+        pub symlink: bool,
+    }
+
+    #[cfg(windows)]
+    impl Default for Context {
+        fn default() -> Self {
+            Context {
+                precompose_unicode: false,
+                ignore_case: true,
+                file_mode: false,
+                symlink: false,
+            }
+        }
+    }
+
+    #[cfg(target_os = "macos")]
+    impl Default for Context {
+        fn default() -> Self {
+            Context {
+                precompose_unicode: true,
+                ignore_case: true,
+                file_mode: true,
+                symlink: true,
+            }
+        }
+    }
+
+    #[cfg(all(unix, not(target_os = "macos")))]
+    impl Default for Context {
+        fn default() -> Self {
+            Context {
+                precompose_unicode: false,
+                ignore_case: false,
+                file_mode: true,
+                symlink: true,
+            }
+        }
+    }
+}
+
 pub mod index;