From 21c59afc71d6ebac71e7d43aba4693bd1edfe092 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jonathan=20M=C3=BCller?= <git@foonathan.net>
Date: Sat, 21 Jan 2017 19:53:37 +0100
Subject: [PATCH] Generalize basic_cpp_entity_ref to use predicate

---
 include/cppast/cpp_entity_ref.hpp  | 22 +++++++++++++++----
 include/cppast/cpp_entity_type.hpp | 12 -----------
 include/cppast/cpp_namespace.hpp   | 33 ++++++++++++++---------------
 src/cpp_namespace.cpp              | 34 ++++++++++++++++++++++++++++++
 4 files changed, 68 insertions(+), 33 deletions(-)
 create mode 100644 src/cpp_namespace.cpp

diff --git a/include/cppast/cpp_entity_ref.hpp b/include/cppast/cpp_entity_ref.hpp
index bcfdda5..bf97f0c 100644
--- a/include/cppast/cpp_entity_ref.hpp
+++ b/include/cppast/cpp_entity_ref.hpp
@@ -6,12 +6,11 @@
 #define CPPAST_CPP_ENTITY_REF_HPP_INCLUDED
 
 #include <cppast/cpp_entity_index.hpp>
-#include <cppast/cpp_entity_type.hpp>
 
 namespace cppast
 {
     /// A basic reference to some kind of [cppast::cpp_entity]().
-    template <typename T, cpp_entity_type Type>
+    template <typename T, typename Predicate>
     class basic_cpp_entity_ref
     {
     public:
@@ -37,7 +36,10 @@ namespace cppast
         /// \returns The [cppast::cpp_entity]() it refers to.
         const T& get(const cpp_entity_index& idx) const noexcept
         {
-            return detail::downcast_entity<const T&>(idx.lookup(target_).value(), Type);
+            auto entity = idx.lookup(target_);
+            DEBUG_ASSERT(Predicate{}(entity.value()), detail::precondition_error_handler{},
+                         "invalid entity");
+            return static_cast<const T&>(entity.value());
         }
 
     private:
@@ -45,8 +47,20 @@ namespace cppast
         std::string   name_;
     };
 
+    /// \exclude
+    namespace detail
+    {
+        struct cpp_entity_ref_predicate
+        {
+            bool operator()(const cpp_entity&)
+            {
+                return true;
+            }
+        };
+    }
+
     /// A [cppast::basic_cpp_entity_ref]() to any [cppast::cpp_entity]().
-    using cpp_entity_ref = basic_cpp_entity_ref<cpp_entity, cpp_entity_type::count>;
+    using cpp_entity_ref = basic_cpp_entity_ref<cpp_entity, detail::cpp_entity_ref_predicate>;
 } // namespace cppast
 
 #endif // CPPAST_CPP_ENTITY_REF_HPP_INCLUDED
diff --git a/include/cppast/cpp_entity_type.hpp b/include/cppast/cpp_entity_type.hpp
index 684e9bf..05c25bc 100644
--- a/include/cppast/cpp_entity_type.hpp
+++ b/include/cppast/cpp_entity_type.hpp
@@ -24,18 +24,6 @@ namespace cppast
 
     /// \returns Whether or not a given entity type is one derived from [cppast::cpp_scope]().
     bool is_scope(cpp_entity_type type) noexcept;
-
-    /// \exclude
-    namespace detail
-    {
-        template <typename T, typename Org>
-        T downcast_entity(Org& org, cpp_entity_type dest_type) noexcept
-        {
-            DEBUG_ASSERT(dest_type == cpp_entity_type::count || org.type() == dest_type,
-                         detail::precondition_error_handler{}, "invalid downcast");
-            return static_cast<T>(org);
-        }
-    } // namespace detail
 } // namespace cppast
 
 #endif // CPPAST_CPP_ENTITY_TYPE_HPP_INCLUDED
diff --git a/include/cppast/cpp_namespace.hpp b/include/cppast/cpp_namespace.hpp
index 94ad7ea..302e202 100644
--- a/include/cppast/cpp_namespace.hpp
+++ b/include/cppast/cpp_namespace.hpp
@@ -7,6 +7,7 @@
 
 #include <cppast/cpp_entity_index.hpp>
 #include <cppast/cpp_entity_ref.hpp>
+#include <cppast/cpp_entity_type.hpp>
 #include <cppast/cpp_scope.hpp>
 
 namespace cppast
@@ -57,16 +58,23 @@ namespace cppast
         {
         }
 
-        cpp_entity_type do_get_entity_type() const noexcept override
-        {
-            return cpp_entity_type::namespace_t;
-        }
+        cpp_entity_type do_get_entity_type() const noexcept override;
 
         bool inline_;
     };
 
+    /// \exclude
+    namespace detail
+    {
+        struct cpp_namespace_ref_predicate
+        {
+            bool operator()(const cpp_entity& e);
+        };
+    } // namespace detail
+
     /// A reference to a [cppast::cpp_namespace]().
-    using cpp_namespace_ref = basic_cpp_entity_ref<cpp_namespace, cpp_entity_type::namespace_t>;
+    using cpp_namespace_ref =
+        basic_cpp_entity_ref<cpp_namespace, detail::cpp_namespace_ref_predicate>;
 
     /// A [cppast::cpp_entity]() modelling a namespace alias.
     class cpp_namespace_alias final : public cpp_entity
@@ -95,10 +103,7 @@ namespace cppast
         {
         }
 
-        cpp_entity_type do_get_entity_type() const noexcept override
-        {
-            return cpp_entity_type::namespace_alias_t;
-        }
+        cpp_entity_type do_get_entity_type() const noexcept override;
 
         cpp_namespace_ref target_;
     };
@@ -130,10 +135,7 @@ namespace cppast
         {
         }
 
-        cpp_entity_type do_get_entity_type() const noexcept override
-        {
-            return cpp_entity_type::using_directive_t;
-        }
+        cpp_entity_type do_get_entity_type() const noexcept override;
 
         cpp_entity_id target_;
     };
@@ -165,10 +167,7 @@ namespace cppast
         {
         }
 
-        cpp_entity_type do_get_entity_type() const noexcept override
-        {
-            return cpp_entity_type::using_declaration_t;
-        }
+        cpp_entity_type do_get_entity_type() const noexcept override;
 
         cpp_entity_id target_;
     };
diff --git a/src/cpp_namespace.cpp b/src/cpp_namespace.cpp
new file mode 100644
index 0000000..3476bf3
--- /dev/null
+++ b/src/cpp_namespace.cpp
@@ -0,0 +1,34 @@
+// 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.
+
+#include <cppast/cpp_namespace.hpp>
+
+#include <cppast/cpp_entity_type.hpp>
+
+using namespace cppast;
+
+cpp_entity_type cpp_namespace::do_get_entity_type() const noexcept
+{
+    return cpp_entity_type::namespace_t;
+}
+
+bool detail::cpp_namespace_ref_predicate::operator()(const cpp_entity& e)
+{
+    return e.type() == cpp_entity_type::namespace_t;
+}
+
+cpp_entity_type cpp_namespace_alias::do_get_entity_type() const noexcept
+{
+    return cpp_entity_type::namespace_alias_t;
+}
+
+cpp_entity_type cpp_using_directive::do_get_entity_type() const noexcept
+{
+    return cpp_entity_type::using_directive_t;
+}
+
+cpp_entity_type cpp_using_declaration::do_get_entity_type() const noexcept
+{
+    return cpp_entity_type::using_declaration_t;
+}