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ui/state.sx

@@ -0,0 +1,59 @@
+#import "modules/std.sx";
+
+// --- State(T) — a handle to persistent storage ---
+
+State :: struct ($T: Type) {
+    ptr: *T;
+
+    get :: (self: State(T)) -> T { self.ptr.*; }
+
+    set :: (self: State(T), val: T) { self.ptr.* = val; }
+}
+
+// --- StateEntry — type-erased storage ---
+
+StateEntry :: struct {
+    id: s64;
+    data: [*]u8;
+    size: s64;
+    generation: s64;
+}
+
+// --- StateStore — manages persistent state ---
+
+StateStore :: struct {
+    entries: List(StateEntry);
+    current_generation: s64;
+
+    init :: (self: *StateStore) {
+        self.entries = List(StateEntry).{};
+        self.current_generation = 0;
+    }
+
+    get_or_create :: (self: *StateStore, id: s64, $T: Type, default: T) -> State(T) {
+        // Search for existing entry
+        i : s64 = 0;
+        while i < self.entries.len {
+            if self.entries.items[i].id == id {
+                self.entries.items[i].generation = self.current_generation;
+                return State(T).{ ptr = xx self.entries.items[i].data };
+            }
+            i += 1;
+        }
+
+        // Create new entry
+        data : [*]u8 = xx context.allocator.alloc(size_of(T));
+        memcpy(data, @default, size_of(T));
+        self.entries.append(StateEntry.{
+            id = id,
+            data = data,
+            size = size_of(T),
+            generation = self.current_generation
+        });
+        State(T).{ ptr = xx data };
+    }
+
+    next_frame :: (self: *StateStore) {
+        self.current_generation += 1;
+    }
+}