in midst of refactor

orchid-api/src/system.rs

@@ -0,0 +1,54 @@
+use orchid_api_derive::{Coding, Hierarchy};
+use orchid_api_traits::Request;
+use ordered_float::NotNan;
+
+use crate::proto::{HostExtNotif, HostExtReq};
+
+/// ID of a system type
+pub type SysDeclId = u16;
+
+/// ID of a system instance
+pub type SysId = u16;
+
+/// Details about a system provided by this library
+#[derive(Coding)]
+pub struct SystemDecl {
+  /// ID of the system, unique within the library
+  pub id: SysDeclId,
+  /// This can be depended upon. Exactly one of each kind will be loaded
+  pub name: String,
+  /// If multiple instances of a system are found, the highest priority will be
+  /// used. This can be used for version counting, but also for fallbacks if a
+  /// negative number is found.
+  ///
+  /// Systems cannot depend on specific versions and older versions of systems
+  /// are never loaded. Compatibility can be determined on a per-system basis
+  /// through an algorithm chosen by the provider.
+  pub priority: NotNan<f64>,
+  /// List of systems needed for this one to work correctly. These will be
+  /// looked up, and an error produced if they aren't found.
+  pub depends: Vec<String>,
+}
+
+/// Host -> extension; instantiate a system according to its [SystemDecl].
+/// Multiple instances of a system may exist in the same address space, so it's
+/// essential that any resource associated with a system finds its system by the
+/// ID in a global map.
+#[derive(Clone, Debug, Coding, Hierarchy)]
+#[extends(HostExtReq)]
+pub struct NewSystem {
+  /// ID of the system
+  pub system: SysDeclId,
+  /// ID of the system instance, unique for the host
+  pub id: SysId,
+  /// Instance IDs for dependencies, in the order that the names appear in the
+  /// declaration
+  pub depends: Vec<SysId>,
+}
+impl Request for NewSystem {
+  type Response = ();
+}
+
+#[derive(Clone, Debug, Coding, Hierarchy)]
+#[extends(HostExtNotif)]
+pub struct SystemDrop(pub SysId);