1 files changed, 70 insertions, 0 deletions
diff --git a/macros/src/analyze.rs b/macros/src/analyze.rs
new file mode 100644
index 00000000..0fc125da
--- /dev/null
+++ b/macros/src/analyze.rs
@@ -0,0 +1,70 @@
+use std::cmp;
+use std::collections::HashMap;
+
+use syn::Ident;
+
+use check::App;
+
+pub type Ownerships = HashMap<Ident, Ownership>;
+
+pub enum Ownership {
+    /// Owned or co-owned by tasks that run at the same priority
+    Owned { priority: u8 },
+    /// Shared by tasks that run at different priorities.
+    ///
+    /// `ceiling` is the maximum value across all the task priorities
+    Shared { ceiling: u8 },
+}
+
+impl Ownership {
+    pub fn is_owned(&self) -> bool {
+        match *self {
+            Ownership::Owned { .. } => true,
+            _ => false,
+        }
+    }
+}
+
+pub fn app(app: &App) -> Ownerships {
+    let mut ownerships = HashMap::new();
+
+    for resource in &app.idle.resources {
+        ownerships.insert(resource.clone(), Ownership::Owned { priority: 0 });
+    }
+
+    for task in app.tasks.values() {
+        for resource in &task.resources {
+            if let Some(ownership) = ownerships.get_mut(resource) {
+                match *ownership {
+                    Ownership::Owned { priority } => {
+                        if priority == task.priority {
+                            *ownership = Ownership::Owned { priority };
+                        } else {
+                            *ownership = Ownership::Shared {
+                                ceiling: cmp::max(priority, task.priority),
+                            };
+                        }
+                    }
+                    Ownership::Shared { ceiling } => {
+                        if task.priority > ceiling {
+                            *ownership = Ownership::Shared {
+                                ceiling: task.priority,
+                            };
+                        }
+                    }
+                }
+
+                continue;
+            }
+
+            ownerships.insert(
+                resource.clone(),
+                Ownership::Owned {
+                    priority: task.priority,
+                },
+            );
+        }
+    }
+
+    ownerships
+}