[ownership] initial struct, parsing, and test framework

src/filter/mod.rs

@@ -1,5 +1,11 @@
 pub use self::size::SizeFilter;
 pub use self::time::TimeFilter;
 
+#[cfg(unix)]
+pub use self::owner::OwnerFilter;
+
 mod size;
 mod time;
+
+#[cfg(unix)]
+mod owner;

src/filter/owner.rs

@@ -0,0 +1,61 @@
+use anyhow::{anyhow, Result};
+
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub struct OwnerFilter {
+    uid: Option<u32>,
+    gid: Option<u32>,
+}
+
+impl OwnerFilter {
+    pub fn from_string(input: &str) -> Result<Self> {
+        let mut it = input.split(':');
+        let (fst, snd) = (it.next(), it.next());
+
+        let uid = match fst {
+            Some("") | None => None,
+            Some(s) => Some(s.parse()?),
+        };
+        let gid = match snd {
+            Some("") | None => None,
+            Some(s) => Some(s.parse()?),
+        };
+
+        if uid.is_none() && gid.is_none() {
+            Err(anyhow!(
+                "'{}' is not a valid user/group specifier. See 'fd --help'.",
+                input
+            ))
+        } else {
+            Ok(OwnerFilter { uid, gid })
+        }
+    }
+}
+
+#[cfg(test)]
+mod owner_parsing {
+    use super::OwnerFilter;
+
+    macro_rules! owner_tests {
+        ($($name:ident: $value:expr => $result:pat,)*) => {
+            $(
+                #[test]
+                fn $name() {
+                    let o = OwnerFilter::from_string($value);
+                    match o {
+                        $result => {},
+                        _ => panic!("{:?} does not match {}", o, stringify!($result)),
+                    }
+                }
+            )*
+        };
+    }
+
+    owner_tests! {
+        empty:      ""      => Err(_),
+        uid_only:   "5"     => Ok(OwnerFilter { uid: Some(5), gid: None   }),
+        uid_gid:    "9:3"   => Ok(OwnerFilter { uid: Some(9), gid: Some(3)}),
+        gid_only:   ":8"    => Ok(OwnerFilter { uid: None,    gid: Some(8)}),
+        colon_only: ":"     => Err(_),
+        trailing:   "5:"    => Ok(OwnerFilter { uid: Some(5), gid: None   }),
+    }
+}