Merge pull request accellera-official#79 from barnasc/accellera-syste…

…mc-example-optional

example using std::optional (note: requires C++17)

tests/systemc/examples/optional/golden/optional.log

@@ -0,0 +1,6 @@
+SystemC Simulation
+attach debug output..
+ name: demo.clk kind: sc_in
+ name: demo.clocked_method kind: sc_method_process
+ name: demo.debug_output kind: sc_out
+program complete

tests/systemc/examples/optional/optional.cpp

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+/*****************************************************************************
+
+  Licensed to Accellera Systems Initiative Inc. (Accellera) under one or
+  more contributor license agreements.  See the NOTICE file distributed
+  with this work for additional information regarding copyright ownership.
+  Accellera licenses this file to you under the Apache License, Version 2.0
+  (the "License"); you may not use this file except in compliance with the
+  License.  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+  implied.  See the License for the specific language governing
+  permissions and limitations under the License.
+
+ *****************************************************************************/
+
+#include <systemc>
+
+#if SC_CPLUSPLUS >= 201703L
+#include <optional>
+#else
+#error "This test requires C++17 features.";
+#endif
+
+struct demo_module : sc_core::sc_module
+{
+  sc_core::sc_in<bool> clk;
+
+  demo_module(sc_core::sc_module_name) : clk("clk")
+  {
+    SC_METHOD(clocked_method);
+    sensitive << clk.pos();
+    dont_initialize();
+  }
+
+  void attach_debug_output(sc_core::sc_signal<int> &signal)
+  {
+    std::cout << "attach debug output.." << std::endl;
+
+    if (!debug_output.has_value())
+    {
+      sc_core::sc_hierarchy_scope scope{ get_hierarchy_scope() };
+      debug_output.emplace("debug_output");
+      debug_output->bind(signal);
+    }
+    else
+    {
+      SC_REPORT_ERROR("optional", "Cannot attach debug output more than once.");
+    }
+  }
+
+private:
+
+  void clocked_method()
+  {
+    if (debug_output) {
+      debug_output->write(debug_output->read() + 1);
+    }
+  }
+
+  // optional output that tracks how many times clocked_method was triggered
+  std::optional<sc_core::sc_out<int> > debug_output;
+
+};
+
+
+int sc_main(int argc, char **argv)
+{
+  demo_module demo("demo");
+  sc_core::sc_signal<int> debug_out("debug_out");
+  sc_core::sc_clock clk("clk", {10, sc_core::SC_NS});
+
+  demo.clk(clk);
+
+  demo.attach_debug_output(debug_out);
+
+  sc_core::sc_start(40.0, sc_core::SC_NS);
+
+  std::vector<sc_core::sc_object*> children = demo.get_child_objects();
+
+  // Print out names and kinds of top-level objects
+  for (unsigned i = 0; i < children.size(); i++)
+  {
+    std::cout << " name: "
+              << children[i]->name()
+              << " kind: " << children[i]->kind()
+              << std::endl;
+  }
+
+  // expected 3 children: clk, debug_output and clocked_method
+  sc_assert(demo.get_child_objects().size() == 3);
+  sc_assert(debug_out == 4);
+
+  std::cout << "program complete" << std::endl;
+  return 0;
+}