1 files changed, 48 insertions, 0 deletions

diff --git a/macros/src/util.rs b/macros/src/util.rs
new file mode 100644
index 00000000..45f1feef
--- /dev/null
+++ b/macros/src/util.rs
@@ -0,0 +1,48 @@
+use std::collections::HashMap;
+
+use syn::Ident;
+
+use syntax::App;
+
+pub type Ceilings = HashMap<Ident, Ceiling>;
+
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub enum Ceiling {
+    Owned,
+    Shared(u8),
+}
+
+impl Ceiling {
+    pub fn is_owned(&self) -> bool {
+        *self == Ceiling::Owned
+    }
+}
+
+pub fn compute_ceilings(app: &App) -> Ceilings {
+    let mut ceilings = HashMap::new();
+
+    for resource in &app.idle.resources {
+        ceilings.insert(resource.clone(), Ceiling::Owned);
+    }
+
+    for task in app.tasks.values() {
+        for resource in &task.resources {
+            if let Some(ceiling) = ceilings.get_mut(resource) {
+                match *ceiling {
+                    Ceiling::Owned => *ceiling = Ceiling::Shared(task.priority),
+                    Ceiling::Shared(old) => {
+                        if task.priority > old {
+                            *ceiling = Ceiling::Shared(task.priority);
+                        }
+                    }
+                }
+
+                continue;
+            }
+
+            ceilings.insert(resource.clone(), Ceiling::Owned);
+        }
+    }
+
+    ceilings
+}