Add enum category example

example/enum_category.cpp

@@ -0,0 +1,116 @@
+// Copyright (C) 2017 Jonathan Müller <jonathanmueller.dev@gmail.com>
+// This file is subject to the license terms in the LICENSE file
+// found in the top-level directory of this distribution.
+
+/// \file
+/// Generates enum category functions.
+
+#include <algorithm>
+#include <cassert>
+#include <iostream>
+
+#include <cppast/cpp_enum.hpp>     // cpp_enum
+#include <cppast/cpp_function.hpp> // cpp_function
+#include <cppast/visitor.hpp>      // visit()
+
+#include "example_parser.hpp"
+
+bool is_category(const cppast::cpp_enum_value& e, const std::string& name)
+{
+    if (auto attr = cppast::has_attribute(e, "generate::enum_category"))
+    {
+        auto iter =
+            std::find_if(attr.value().arguments().value().begin(),
+                         attr.value().arguments().value().end(),
+                         [&](const cppast::cpp_token& tok) { return tok.spelling == name; });
+        return iter != attr.value().arguments().value().end();
+    }
+    else
+        return false;
+}
+
+const cppast::cpp_enum& get_enum(const cppast::cpp_entity_index&       index,
+                                 const cppast::cpp_function_parameter& param)
+{
+    auto& param_type = param.type();
+    // is an enum
+    assert(param_type.kind() == cppast::cpp_type_kind::user_defined_t);
+    auto& definition =
+        static_cast<const cppast::cpp_user_defined_type&>(param_type).entity().get(index)[0u].get();
+
+    assert(definition.kind() == cppast::cpp_entity_kind::enum_t);
+    return static_cast<const cppast::cpp_enum&>(definition);
+}
+
+void generate_enum_category(const cppast::cpp_entity_index& index, const cppast::cpp_file& file)
+{
+    cppast::visit(file,
+                  [](const cppast::cpp_entity& e) {
+                      // only visit function declarations that have the attribute set
+                      return (e.kind() == cppast::cpp_entity_kind::function_t
+                              && !cppast::is_definition(e)
+                              && cppast::has_attribute(e, "generate::enum_category"))
+                             // or all namespaces
+                             || e.kind() == cppast::cpp_entity_kind::namespace_t;
+                  },
+                  [&](const cppast::cpp_entity& e, const cppast::visitor_info& info) {
+                      if (e.kind() == cppast::cpp_entity_kind::function_t)
+                      {
+                          // a new function, generate implementation
+                          assert(info.is_new_entity());
+
+                          auto category = cppast::has_attribute(e, "generate::enum_category")
+                                              .value()
+                                              .arguments()
+                                              .value()
+                                              .as_string();
+
+                          auto& func = static_cast<const cppast::cpp_function&>(e);
+                          // return type must be bool
+                          assert(func.return_type().kind() == cppast::cpp_type_kind::builtin_t
+                                 && static_cast<const cppast::cpp_builtin_type&>(func.return_type())
+                                            .builtin_type_kind()
+                                        == cppast::cpp_bool);
+
+                          // single parameter...
+                          assert(std::next(func.parameters().begin()) == func.parameters().end());
+                          auto& param = *func.parameters().begin();
+                          auto& enum_ = get_enum(index, param);
+
+                          // generate function definition
+                          std::cout << "inline bool " << func.name() << "("
+                                    << cppast::to_string(param.type()) << " e) {\n";
+
+                          // generate switch
+                          std::cout << "  switch (e) {\n";
+                          for (const auto& enumerator : enum_)
+                          {
+                              std::cout << "  case " << enum_.name() << "::" << enumerator.name()
+                                        << ":\n";
+                              if (is_category(enumerator, category))
+                                  std::cout << "    return true;\n";
+                              else
+                                  std::cout << "    return false;\n";
+                          }
+                          std::cout << "  }\n";
+
+                          std::cout << "}\n\n";
+                      }
+                      else if (e.kind() == cppast::cpp_entity_kind::namespace_t)
+                      {
+                          if (info.event == cppast::visitor_info::container_entity_enter)
+                              // open namespace
+                              std::cout << "namespace " << e.name() << " {\n\n";
+                          else // if (info.event == cppast::visitor_info::container_entity_exit)
+                              // close namespace
+                              std::cout << "}\n";
+                      }
+                  });
+}
+
+int main(int argc, char* argv[])
+{
+    cppast::cpp_entity_index index;
+    return example_main(argc, argv, index,
+                        [&](const cppast::cpp_file& file) { generate_enum_category(index, file); });
+}