feat(furvm): add a thing

furvm/src/executor.cpp

@@ -17,4 +17,34 @@ std::shared_ptr<executor> executor::create(const std::shared_ptr<context>& conte
     return std::move(ex);
 }
 
+void executor::push_frame(const std::shared_ptr<mod>& mod, std::size_t position) {
+    m_frames.emplace((struct executor::frame){ mod, position, m_stack.size() });
+}
+
+struct executor::frame executor::pop_frame() {
+    struct executor::frame frame = m_frames.top();
+    m_frames.pop();
+    return frame;
+}
+
+struct executor::frame executor::frame() const {
+    return m_frames.top();
+}
+
+void executor::push_thing(const std::shared_ptr<class thing>& thing) {
+    m_stack.push(thing);
+}
+
+std::shared_ptr<class thing> executor::pop_thing() {
+    if (m_frames.top().stackBase >= m_stack.size()) return {};
+    std::shared_ptr<class thing> top = std::move(m_stack.top());
+    m_stack.pop();
+    return top;
+}
+
+std::shared_ptr<class thing> executor::thing() const {
+    if (m_frames.top().stackBase >= m_stack.size()) return {};
+    return m_stack.top();
+}
+
 } // namespace furvm