GH-807 Support named lookup of signals, used by await keyword

src/script/instances/script_instance.cpp

@@ -122,23 +122,33 @@ bool OScriptInstance::set(const StringName& p_name, const Variant& p_value, Prop
 
 bool OScriptInstance::get(const StringName& p_name, Variant& p_value, PropertyError* r_err)
 {
+    // First check if we have a member variable
     const String variable_name = _get_variable_name_from_path(p_name);
-
-    OScriptVirtualMachine::Variable* variable = _vm.get_variable(variable_name);
-    if (!variable || !variable->exported)
+    if (_vm.has_variable(variable_name))
     {
+        OScriptVirtualMachine::Variable* variable = _vm.get_variable(variable_name);
+        if (!variable || !variable->exported)
+        {
+            if (r_err)
+                *r_err = PROP_NOT_FOUND;
+            return false;
+        }
+
         if (r_err)
-            *r_err = PROP_NOT_FOUND;
+            *r_err = PROP_OK;
 
-        return false;
+        p_value = variable->value;
+        return true;
     }
 
-    if (r_err)
-        *r_err = PROP_OK;
-
-    p_value = variable->value;
+    // Next check signals - for named access, i.e. "await obj.signal"
+    if (_vm.has_signal(p_name))
+    {
+        p_value = _vm.get_signal(p_name);
+        return true;
+    }
 
-    return true;
+    return false;
 }
 
 GDExtensionPropertyInfo* OScriptInstance::get_property_list(uint32_t* r_count)

src/script/vm/script_vm.cpp

@@ -948,6 +948,11 @@ bool OScriptVirtualMachine::register_variable(const Ref<OScriptVariable>& p_vari
     return true;
 }
 
+bool OScriptVirtualMachine::has_variable(const StringName& p_name) const
+{
+    return _variables.has(p_name);
+}
+
 OScriptVirtualMachine::Variable* OScriptVirtualMachine::get_variable(const StringName& p_name) const
 {
     const HashMap<StringName, Variable>::ConstIterator E = _variables.find(p_name);
@@ -976,6 +981,17 @@ bool OScriptVirtualMachine::set_variable(const StringName& p_name, const Variant
     return true;
 }
 
+bool OScriptVirtualMachine::has_signal(const StringName& p_name) const
+{
+    return _script->has_script_signal(p_name);
+}
+
+Variant OScriptVirtualMachine::get_signal(const StringName& p_name)
+{
+    ERR_FAIL_COND_V_MSG(!_script->has_script_signal(p_name), Variant(), "No signal with name '" + p_name + "' found.");
+    return Signal(get_owner(), p_name);
+}
+
 bool OScriptVirtualMachine::register_function(const Ref<OScriptFunction>& p_function)
 {
     ERR_FAIL_COND_V_MSG(!p_function.is_valid(), false, "Cannot register function that is invalid.");

src/script/vm/script_vm.h

@@ -207,6 +207,11 @@ class OScriptVirtualMachine
     /// @return true if the variable was registered successfully, false otherwise
     bool register_variable(const Ref<OScriptVariable>& p_variable);
 
+    /// Check whether the script has a variable
+    /// @param p_name the variable name
+    /// @return true if the variable exists, false otherwise
+    bool has_variable(const StringName& p_name) const;
+
     /// Gets the variable by name
     /// @param p_name the variable name
     /// @return the variable if found, otherwise returns null
@@ -224,6 +229,16 @@ class OScriptVirtualMachine
     /// @return true if the value was set, false otherwise
     bool set_variable(const StringName& p_name, const Variant& p_value);
 
+    /// Check whether the script instance has such a signal
+    /// @param p_name the signal name
+    /// @return true if the signal exists, false otherwise
+    bool has_signal(const StringName& p_name) const;
+
+    /// Get the signal instance for the given name.
+    /// @param p_name the signal name
+    /// @return the signal instance, should not be called without verifying signal exists
+    Variant get_signal(const StringName& p_name);
+
     /// Register a function
     /// @param p_function the function to be registered
     /// @return true if the function was registered successfully, false othrewise