From 917ca5ffdc476123c28e610b1b8b3868cedd45a6 Mon Sep 17 00:00:00 2001
From: Mike <mike@prime31.com>
Date: Sun, 7 Jun 2020 17:28:49 -0700
Subject: [PATCH] allow inserts

---
 zig-ecs/src/signals/signal.zig | 16 +++++--
 zig-ecs/src/signals/sink.zig   | 88 ++++++++++++++++++++++++++++++----
 2 files changed, 91 insertions(+), 13 deletions(-)

diff --git a/zig-ecs/src/signals/signal.zig b/zig-ecs/src/signals/signal.zig
index c14bf8b..98e2368 100644
--- a/zig-ecs/src/signals/signal.zig
+++ b/zig-ecs/src/signals/signal.zig
@@ -77,9 +77,6 @@ test "Signal/Sink" {
     sink.connect(tester);
     std.testing.expectEqual(@as(usize, 1), signal.size());
 
-    sink.connect(tester);
-    std.testing.expectEqual(@as(usize, 1), signal.size());
-
     // bound listener
     var thing = Thing{};
     sink.connectBound(&thing, "tester");
@@ -93,3 +90,16 @@ test "Signal/Sink" {
     sink.disconnectBound(&thing);
     std.testing.expectEqual(@as(usize, 0), signal.size());
 }
+
+test "Sink Before null" {
+    var signal = Signal(u32).init(std.testing.allocator);
+    defer signal.deinit();
+
+    var sink = signal.sink();
+    sink.connect(tester);
+    std.testing.expectEqual(@as(usize, 1), signal.size());
+
+    var thing = Thing{};
+    sink.before(null).connectBound(&thing, "tester");
+    std.testing.expectEqual(@as(usize, 2), signal.size());
+}
diff --git a/zig-ecs/src/signals/sink.zig b/zig-ecs/src/signals/sink.zig
index d915ab9..b4a6986 100644
--- a/zig-ecs/src/signals/sink.zig
+++ b/zig-ecs/src/signals/sink.zig
@@ -8,40 +8,108 @@ pub fn Sink(comptime Event: type) type {
     return struct {
         const Self = @This();
 
+        insert_index: usize,
+
         /// the Signal this Sink is temporarily wrapping
         var owning_signal: *Signal(Event) = undefined;
 
         pub fn init(signal: *Signal(Event)) Self {
             owning_signal = signal;
-            return Self{};
+            return Self{ .insert_index = owning_signal.calls.items.len };
+        }
+
+        pub fn before(self: Self, callback: ?fn (Event) void) Self {
+            if (callback) |cb| {
+                if (self.indexOf(cb)) |index| {
+                    return Self{ .insert_index = index };
+                }
+            }
+            return self;
+        }
+
+        pub fn beforeBound(self: Self, ctx: var) Self {
+            if (@typeInfo(@TypeOf(ctx)) == .Pointer) {
+                if (self.indexOfBound(ctx)) |index| {
+                    return Self{ .insert_index = index };
+                }
+            }
+            return self;
         }
 
         pub fn connect(self: Self, callback: fn (Event) void) void {
-            self.disconnect(callback);
-            _ = owning_signal.calls.append(Delegate(Event).initFree(callback)) catch unreachable;
+            std.debug.assert(self.indexOf(callback) == null);
+            _ = owning_signal.calls.insert(self.insert_index, Delegate(Event).initFree(callback)) catch unreachable;
         }
 
         pub fn connectBound(self: Self, ctx: var, comptime fn_name: []const u8) void {
-            self.disconnectBound(ctx);
-            _ = owning_signal.calls.append(Delegate(Event).initBound(ctx, fn_name)) catch unreachable;
+            std.debug.assert(self.indexOfBound(ctx) == null);
+            _ = owning_signal.calls.insert(self.insert_index, Delegate(Event).initBound(ctx, fn_name)) catch unreachable;
         }
 
         pub fn disconnect(self: Self, callback: fn (Event) void) void {
+            if (self.indexOf(callback)) |index| {
+                _ = owning_signal.calls.swapRemove(index);
+            }
+        }
+
+        pub fn disconnectBound(self: Self, ctx: var) void {
+            if (self.indexOfBound(ctx)) |index| {
+                _ = owning_signal.calls.swapRemove(index);
+            }
+        }
+
+        fn indexOf(self: Self, callback: fn (Event) void) ?usize {
             for (owning_signal.calls.items) |call, i| {
                 if (call.containsFree(callback)) {
-                    _ = owning_signal.calls.swapRemove(i);
-                    break;
+                    return i;
                 }
             }
+            return null;
         }
 
-        pub fn disconnectBound(self: Self, ctx: var) void {
+        fn indexOfBound(self: Self, ctx: var) ?usize {
             for (owning_signal.calls.items) |call, i| {
                 if (call.containsBound(ctx)) {
-                    _ = owning_signal.calls.swapRemove(i);
-                    break;
+                    return i;
                 }
             }
+            return null;
         }
     };
 }
+
+fn tester(param: u32) void {
+    std.testing.expectEqual(@as(u32, 666), param);
+}
+
+const Thing = struct {
+    field: f32 = 0,
+
+    pub fn tester(self: *Thing, param: u32) void {
+        std.testing.expectEqual(@as(u32, 666), param);
+    }
+};
+
+test "Sink Before free" {
+    var signal = Signal(u32).init(std.testing.allocator);
+    defer signal.deinit();
+
+    signal.sink().connect(tester);
+    std.testing.expectEqual(signal.sink().indexOf(tester).?, 0);
+
+    var thing = Thing{};
+    signal.sink().before(tester).connectBound(&thing, "tester");
+    std.testing.expectEqual(signal.sink().indexOfBound(&thing).?, 0);
+}
+
+test "Sink Before bound" {
+    var signal = Signal(u32).init(std.testing.allocator);
+    defer signal.deinit();
+
+    var thing = Thing{};
+    signal.sink().connectBound(&thing, "tester");
+    std.testing.expectEqual(signal.sink().indexOfBound(&thing).?, 0);
+
+    signal.sink().beforeBound(&thing).connect(tester);
+    std.testing.expectEqual(signal.sink().indexOf(tester).?, 0);
+}
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