frame for basic parsing (#450)

git-refspec/src/lib.rs

@@ -7,6 +7,8 @@ use bstr::{BStr, BString};
 /// The way to interpret a refspec.
 #[derive(PartialEq, Eq, Copy, Clone, Hash, Debug)]
 pub enum Mode {
+    /// Apply standard rules for refspecs which are including refs with specific rules related to allowing fast forwards of destinations.
+    Normal,
     /// Even though according to normal rules a non-fastforward would be denied, override this and reset a ref forcefully in the destination.
     Force,
     /// Instead of considering matching refs included, we consider them excluded. This applies only to the source side of a refspec.
@@ -40,6 +42,9 @@ pub struct RefSpec {
     dest: Option<BString>,
 }
 
+pub mod parse;
+pub use parse::function::parse;
+
 mod spec {
     use crate::{RefSpec, RefSpecRef};
 

git-refspec/src/parse.rs

@@ -0,0 +1,18 @@
+#[derive(Debug, thiserror::Error)]
+pub enum Error {
+    #[error("Empty refspecs are invalid")]
+    Empty,
+    #[error("Negative refspecs cannot have destinations as they exclude sources")]
+    NegativeWithDestination,
+}
+
+pub(crate) mod function {
+    use crate::parse::Error;
+    use crate::{Operation, RefSpecRef};
+    use bstr::BStr;
+
+    /// Parse `spec` for use in `operation` and return it if it is valid.
+    pub fn parse(mut _spec: &BStr, _operation: Operation) -> Result<RefSpecRef<'_>, Error> {
+        todo!()
+    }
+}

git-refspec/tests/parse/mod.rs

@@ -5,3 +5,31 @@ use git_testtools::scripted_fixture_repo_read_only;
 fn baseline() {
     let _dir = scripted_fixture_repo_read_only("make_baseline.sh").unwrap();
 }
+
+mod invalid {
+    use git_refspec::{parse, parse::Error, Operation};
+
+    #[test]
+    #[ignore]
+    fn empty() {
+        assert!(matches!(parse("".into(), Operation::Fetch).unwrap_err(), Error::Empty));
+        assert!(matches!(parse("".into(), Operation::Push).unwrap_err(), Error::Empty));
+    }
+
+    #[test]
+    #[ignore]
+    fn negative_with_destination() {
+        assert!(matches!(
+            parse("^a:b".into(), Operation::Fetch).unwrap_err(),
+            Error::NegativeWithDestination
+        ));
+        assert!(matches!(
+            parse("a:b".into(), Operation::Fetch).unwrap_err(),
+            Error::NegativeWithDestination
+        ));
+    }
+
+    mod fetch {}
+
+    mod push {}
+}