From 253b163f3bba57f40ad485e0ea2d27b95ab95bf2 Mon Sep 17 00:00:00 2001
From: Ben Deane <ben@elbeno.com>
Date: Fri, 30 Aug 2024 15:20:07 -0600
Subject: [PATCH] :bug: Fix handler short-circuiting

The handler should call all the callbacks that match a message, not just the
first that matches.

This is consistent with the indexed_handler behaviour.

NOTE: The order of calling the callbacks is not defined.
---
 include/msg/handler.hpp |  6 ++++--
 test/msg/handler.cpp    | 21 ++++++++++++++++++++-
 2 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/include/msg/handler.hpp b/include/msg/handler.hpp
index d587982a..2a86ec95 100644
--- a/include/msg/handler.hpp
+++ b/include/msg/handler.hpp
@@ -21,8 +21,10 @@ struct handler : handler_interface<BaseMsg, ExtraCallbackArgs...> {
 
     auto handle(BaseMsg const &msg,
                 ExtraCallbackArgs... args) const -> bool final {
-        bool const found_valid_callback = stdx::any_of(
-            [&](auto &callback) { return callback.handle(msg, args...); },
+        auto const found_valid_callback = stdx::apply(
+            [&](auto &...cbs) -> bool {
+                return (0u | ... | cbs.handle(msg, args...));
+            },
             callbacks);
         if (!found_valid_callback) {
             CIB_ERROR("None of the registered callbacks claimed this message:");
diff --git a/test/msg/handler.cpp b/test/msg/handler.cpp
index b4a07b06..95e5533b 100644
--- a/test/msg/handler.cpp
+++ b/test/msg/handler.cpp
@@ -93,7 +93,7 @@ TEST_CASE("log mismatch when no match", "[handler]") {
 
 TEST_CASE("match and dispatch only one callback", "[handler]") {
     auto callback1 = msg::callback<"cb1", msg_defn>(
-        id_match<0x80>, [&](msg::const_view<msg_defn>) { CHECK(false); });
+        id_match<0x80>, [](msg::const_view<msg_defn>) { CHECK(false); });
     auto callback2 = msg::callback<"cb2", msg_defn>(
         id_match<0x44>, [](msg::const_view<msg_defn>) { dispatched = true; });
     auto const msg = std::array{0x4400ba11u, 0x0042d00du};
@@ -107,6 +107,25 @@ TEST_CASE("match and dispatch only one callback", "[handler]") {
     CHECK(dispatched);
 }
 
+TEST_CASE("dispatch all callbacks that match", "[handler]") {
+    int count{};
+
+    auto callback1 = msg::callback<"cb1", msg_defn>(
+        id_match<0x80>, [](msg::const_view<msg_defn>) { CHECK(false); });
+    auto callback2 = msg::callback<"cb2", msg_defn>(
+        id_match<0x44>, [&](msg::const_view<msg_defn>) { ++count; });
+    auto callback3 = msg::callback<"cb3", msg_defn>(
+        id_match<0x44>, [&](msg::const_view<msg_defn>) { ++count; });
+    auto const msg = std::array{0x4400ba11u, 0x0042d00du};
+
+    auto callbacks = stdx::make_tuple(callback1, callback2, callback3);
+    static auto handler =
+        msg::handler<decltype(callbacks), decltype(msg)>{callbacks};
+
+    CHECK(handler.handle(msg));
+    CHECK(count == 2);
+}
+
 namespace {
 template <typename T>
 using uint8_view =