5 files changed, 20 insertions, 5 deletions
diff --git a/Source/Core/InputCommon/ControllerInterface/ControllerInterface.cpp b/Source/Core/InputCommon/ControllerInterface/ControllerInterface.cpp
index cc80b7b234..cf726698f1 100644
--- a/Source/Core/InputCommon/ControllerInterface/ControllerInterface.cpp
+++ b/Source/Core/InputCommon/ControllerInterface/ControllerInterface.cpp
@@ -160,6 +160,14 @@ void ControllerInterface::AddDevice(std::shared_ptr<ciface::Core::Device> device
   m_devices.emplace_back(std::move(device));
 }
 
+void ControllerInterface::RemoveDevice(std::function<bool(const ciface::Core::Device*)> callback)
+{
+  std::lock_guard<std::mutex> lk(m_devices_mutex);
+  m_devices.erase(std::remove_if(m_devices.begin(), m_devices.end(),
+                                 [&callback](const auto& dev) { return callback(dev.get()); }),
+                  m_devices.end());
+}
+
 //
 // UpdateInput
 //
diff --git a/Source/Core/InputCommon/ControllerInterface/ControllerInterface.h b/Source/Core/InputCommon/ControllerInterface/ControllerInterface.h
index 24f92fd3c1..198a2c180b 100644
--- a/Source/Core/InputCommon/ControllerInterface/ControllerInterface.h
+++ b/Source/Core/InputCommon/ControllerInterface/ControllerInterface.h
@@ -122,6 +122,7 @@ public:
   void Reinitialize();
   void Shutdown();
   void AddDevice(std::shared_ptr<ciface::Core::Device> device);
+  void RemoveDevice(std::function<bool(const ciface::Core::Device*)> callback);
   bool IsInit() const { return m_is_init; }
   void UpdateReference(ControlReference* control,
                        const ciface::Core::DeviceQualifier& default_device) const;
diff --git a/Source/Core/InputCommon/ControllerInterface/Device.h b/Source/Core/InputCommon/ControllerInterface/Device.h
index e3fe4c11cd..657ece5016 100644
--- a/Source/Core/InputCommon/ControllerInterface/Device.h
+++ b/Source/Core/InputCommon/ControllerInterface/Device.h
@@ -98,6 +98,7 @@ public:
   virtual std::string GetName() const = 0;
   virtual std::string GetSource() const = 0;
   virtual void UpdateInput() {}
+  virtual bool IsValid() const { return true; }
   const std::vector<Input*>& Inputs() const { return m_inputs; }
   const std::vector<Output*>& Outputs() const { return m_outputs; }
   Input* FindInput(const std::string& name) const;
diff --git a/Source/Core/InputCommon/ControllerInterface/ExpressionParser.cpp b/Source/Core/InputCommon/ControllerInterface/ExpressionParser.cpp
index 6e9b8b77ab..2960888148 100644
--- a/Source/Core/InputCommon/ControllerInterface/ExpressionParser.cpp
+++ b/Source/Core/InputCommon/ControllerInterface/ExpressionParser.cpp
@@ -235,8 +235,9 @@ public:
   ControlQualifier qualifier;
   Device::Control* control;
 
-  ControlExpression(ControlQualifier qualifier_, Device::Control* control_)
-      : qualifier(qualifier_), control(control_)
+  ControlExpression(ControlQualifier qualifier_, std::shared_ptr<Device> device,
+                    Device::Control* control_)
+      : qualifier(qualifier_), control(control_), m_device(device)
   {
   }
 
@@ -244,6 +245,8 @@ public:
   void SetValue(ControlState value) override { control->ToOutput()->SetGatedState(value); }
   int CountNumControls() override { return 1; }
   operator std::string() override { return "`" + (std::string)qualifier + "`"; }
+private:
+  std::shared_ptr<Device> m_device;
 };
 
 class BinaryExpression : public ExpressionNode
@@ -393,6 +396,7 @@ private:
     {
     case TOK_CONTROL:
     {
+      std::shared_ptr<Device> device = finder.FindDevice(tok.qualifier);
       Device::Control* control = finder.FindControl(tok.qualifier);
       if (control == nullptr)
       {
@@ -400,7 +404,7 @@ private:
         return EXPRESSION_PARSE_SUCCESS;
       }
 
-      *expr_out = new ControlExpression(tok.qualifier, control);
+      *expr_out = new ControlExpression(tok.qualifier, device, control);
       return EXPRESSION_PARSE_SUCCESS;
     }
     case TOK_LPAREN:
@@ -550,10 +554,11 @@ ExpressionParseStatus ParseExpression(const std::string& str, ControlFinder& fin
   qualifier.control_name = str;
   qualifier.has_device = false;
 
+  std::shared_ptr<Device> device = finder.FindDevice(qualifier);
   Device::Control* control = finder.FindControl(qualifier);
   if (control)
   {
-    *expr_out = new Expression(new ControlExpression(qualifier, control));
+    *expr_out = new Expression(new ControlExpression(qualifier, device, control));
     return EXPRESSION_PARSE_SUCCESS;
   }
 
diff --git a/Source/Core/InputCommon/ControllerInterface/ExpressionParser.h b/Source/Core/InputCommon/ControllerInterface/ExpressionParser.h
index 992ca65f03..2c8f5a793f 100644
--- a/Source/Core/InputCommon/ControllerInterface/ExpressionParser.h
+++ b/Source/Core/InputCommon/ControllerInterface/ExpressionParser.h
@@ -37,10 +37,10 @@ public:
       : container(container_), default_device(default_), is_input(is_input_)
   {
   }
+  std::shared_ptr<Core::Device> FindDevice(ControlQualifier qualifier);
   Core::Device::Control* FindControl(ControlQualifier qualifier);
 
 private:
-  std::shared_ptr<Core::Device> FindDevice(ControlQualifier qualifier);
   const Core::DeviceContainer& container;
   const Core::DeviceQualifier& default_device;
   bool is_input;