cocoa_bridge: Idea for black box map run function

New `run_key_action()` will be called from Objective C. It will:

* Get the action for a `Map` mapping and return it, so that the
  corresponding keys can be pressed in Cocoa/Carbon
* Run a `Command` mapping
* Somehow manage mode scoping in conjunction with the Objective C side

The new `KeyActionResult` allows us to tell Objective C what type of
action should be run (`Map`, `Command`, or `Mode`), along with
additional information (for now just the action keys in the case of a
`Map` mapping).

The question is how to hold on to state, keeping the parsed mappings in
memory on the Rust side when called over FFI.

2 files changed, 17 insertions, 2 deletions

diff --git a/src/cocoa_bridge.rs b/src/cocoa_bridge.rs
index 3ddacc9..d57e5ee 100644
--- a/src/cocoa_bridge.rs
+++ b/src/cocoa_bridge.rs
@@ -1,7 +1,7 @@
 use cocoa::base::nil;
 use cocoa::foundation::{NSArray, NSAutoreleasePool, NSDictionary};
 
-use MapGroup;
+use {HeadphoneButton, MapGroup, MapKind};
 
 #[repr(C)]
 struct renameMeMapGroup {
@@ -36,6 +36,21 @@ map <down> j";
 // or run command (from Rust?)
 // Somehow: switch mode inside Rust
 
+#[repr(C)]
+pub struct KeyActionResult<'a> {
+    pub action: Option<&'a [char]>,
+    pub kind: MapKind,
+}
+
+pub extern "C" fn run_key_action(
+    trigger: &[HeadphoneButton]
+) -> KeyActionResult {
+    KeyActionResult {
+        action: None,
+        kind: MapKind::Map,
+    }
+}
+
 
 mod tests {
     use super::*;
diff --git a/src/lib.rs b/src/lib.rs
index e6260ed..7fb0b92 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -6,4 +6,4 @@ extern crate combine;
 mod cocoa_bridge;
 mod parser;
 
-use parser::MapGroup;
+use parser::{HeadphoneButton, MapGroup, MapKind};