Parse template parameters and part of alias template

include/cppast/cpp_alias_template.hpp

@@ -14,6 +14,8 @@ namespace cppast
     class cpp_alias_template final : public cpp_template
     {
     public:
+        static cpp_entity_kind kind() noexcept;
+
         /// Builder for [cppast::cpp_alias_template]().
         class builder : public basic_builder<cpp_alias_template, cpp_type_alias>
         {

include/cppast/cpp_template.hpp

@@ -39,6 +39,8 @@ namespace cppast
             {
             }
 
+            basic_builder(basic_builder&&) = default;
+
             /// \effects Adds a parameter.
             void add_parameter(std::unique_ptr<cpp_template_parameter> parameter)
             {
@@ -46,6 +48,12 @@ namespace cppast
                     .parameters_.push_back(*template_entity, std::move(parameter));
             }
 
+            /// \returns The not yet finished template.
+            T& get() const noexcept
+            {
+                return *template_entity;
+            }
+
             /// \effects Registers the template.
             /// \returns The finished template.
             std::unique_ptr<T> finish(const cpp_entity_index& idx, cpp_entity_id id)

include/cppast/cpp_template_parameter.hpp

@@ -48,6 +48,8 @@ namespace cppast
     class cpp_template_type_parameter final : public cpp_template_parameter
     {
     public:
+        static cpp_entity_kind kind() noexcept;
+
         /// \returns A newly created and registered template type parameter.
         /// \notes The `default_type` may be `nullptr` in which case the parameter has no default.
         static std::unique_ptr<cpp_template_type_parameter> build(

src/cpp_alias_template.cpp

@@ -8,7 +8,12 @@
 
 using namespace cppast;
 
-cpp_entity_kind cpp_alias_template::do_get_entity_kind() const noexcept
+cpp_entity_kind cpp_alias_template::kind() noexcept
 {
     return cpp_entity_kind::alias_template_t;
 }
+
+cpp_entity_kind cpp_alias_template::do_get_entity_kind() const noexcept
+{
+    return kind();
+}

src/cpp_template_parameter.cpp

@@ -31,11 +31,16 @@ std::unique_ptr<cpp_template_type_parameter> cpp_template_type_parameter::build(
     return result;
 }
 
-cpp_entity_kind cpp_template_type_parameter::do_get_entity_kind() const noexcept
+cpp_entity_kind cpp_template_type_parameter::kind() noexcept
 {
     return cpp_entity_kind::template_type_parameter_t;
 }
 
+cpp_entity_kind cpp_template_type_parameter::do_get_entity_kind() const noexcept
+{
+    return kind();
+}
+
 bool detail::cpp_template_parameter_ref_predicate::operator()(const cpp_entity& e)
 {
     return e.kind() == cpp_entity_kind::template_type_parameter_t;

src/libclang/debug_helper.cpp

@@ -39,6 +39,13 @@ void detail::print_cursor_info(const CXCursor& cur) noexcept
                 cxstring(clang_getCursorUSR(cur)).c_str());
 }
 
+void detail::print_type_info(const CXType& type) noexcept
+{
+    std::lock_guard<std::mutex> lock(mtx);
+    std::printf("[debug] type '%s' (%s)\n", cxstring(clang_getTypeSpelling(type)).c_str(),
+                get_type_kind_spelling(type).c_str());
+}
+
 void detail::print_tokens(const CXTranslationUnit& tu, const CXFile& file,
                           const CXCursor& cur) noexcept
 {

src/libclang/debug_helper.hpp

@@ -19,6 +19,8 @@ namespace cppast
 
         void print_cursor_info(const CXCursor& cur) noexcept;
 
+        void print_type_info(const CXType& type) noexcept;
+
         void print_tokens(const CXTranslationUnit& tu, const CXFile& file,
                           const CXCursor& cur) noexcept;
     }

src/libclang/parse_functions.cpp

@@ -68,7 +68,7 @@ void detail::comment_context::match(cpp_entity& e, unsigned line) const
 }
 
 std::unique_ptr<cpp_entity> detail::parse_entity(const detail::parse_context& context,
-                                                 const CXCursor&              cur) try
+                                                 const CXCursor& cur, bool as_template) try
 {
     auto kind = clang_getCursorKind(cur);
     switch (kind)
@@ -90,7 +90,7 @@ std::unique_ptr<cpp_entity> detail::parse_entity(const detail::parse_context& co
 
     case CXCursor_TypeAliasDecl:
     case CXCursor_TypedefDecl:
-        return parse_cpp_type_alias(context, cur);
+        return parse_cpp_type_alias(context, cur, as_template);
     case CXCursor_EnumDecl:
         return parse_cpp_enum(context, cur);
     case CXCursor_ClassDecl:
@@ -117,6 +117,9 @@ std::unique_ptr<cpp_entity> detail::parse_entity(const detail::parse_context& co
     case CXCursor_Destructor:
         return parse_cpp_destructor(context, cur);
 
+    case CXCursor_TypeAliasTemplateDecl:
+        return parse_cpp_alias_template(context, cur);
+
     default:
         break;
     }

src/libclang/parse_functions.hpp

@@ -60,6 +60,13 @@ namespace cppast
 
         std::unique_ptr<cpp_type> parse_type(const parse_context& context, const CXType& type);
 
+        // parse the type starting at the current token stream
+        // and ends at the given iterator
+        // this is required for situations where there is no type exposed,
+        // like default type of a template type parameter
+        std::unique_ptr<cpp_type> parse_raw_type(const parse_context& context, token_stream& stream,
+                                                 token_iterator end);
+
         std::unique_ptr<cpp_expression> parse_expression(const parse_context& context,
                                                          const CXCursor&      cur);
         // parse the expression starting at the current token in the stream
@@ -93,7 +100,7 @@ namespace cppast
                                                                 const CXCursor&      cur);
 
         std::unique_ptr<cpp_entity> parse_cpp_type_alias(const parse_context& context,
-                                                         const CXCursor&      cur);
+                                                         const CXCursor& cur, bool as_template);
         std::unique_ptr<cpp_entity> parse_cpp_enum(const parse_context& context,
                                                    const CXCursor&      cur);
         std::unique_ptr<cpp_entity> parse_cpp_class(const parse_context& context,
@@ -116,7 +123,12 @@ namespace cppast
         std::unique_ptr<cpp_entity> parse_cpp_destructor(const parse_context& context,
                                                          const CXCursor&      cur);
 
-        std::unique_ptr<cpp_entity> parse_entity(const parse_context& context, const CXCursor& cur);
+        std::unique_ptr<cpp_entity> parse_cpp_alias_template(const parse_context& context,
+                                                             const CXCursor&      cur);
+
+        // as_template: true, iff currently parsing a template
+        std::unique_ptr<cpp_entity> parse_entity(const parse_context& context, const CXCursor& cur,
+                                                 bool as_template = false);
     }
 } // namespace cppast::detail
 

src/libclang/template_parser.cpp

@@ -0,0 +1,211 @@
+// 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_alias_template.hpp>
+
+#include "libclang_visitor.hpp"
+#include "parse_functions.hpp"
+
+using namespace cppast;
+
+namespace
+{
+    template <typename TemplateT, typename EntityT>
+    typename TemplateT::builder get_builder(const detail::parse_context& context,
+                                            const CXCursor&              cur)
+    {
+        // we need the actual entity first, then the parameters
+        // so two visit calls are required
+
+        auto result = clang_getNullCursor();
+        detail::visit_children(cur, [&](const CXCursor& child) {
+            auto kind = clang_getCursorKind(child);
+            if (kind == CXCursor_TemplateTypeParameter || kind == CXCursor_NonTypeTemplateParameter
+                || kind == CXCursor_TemplateTemplateParameter)
+                return;
+            DEBUG_ASSERT(clang_Cursor_isNull(result), detail::parse_error_handler{}, cur,
+                         "unexpected child of template");
+            result = child;
+        });
+        DEBUG_ASSERT(!clang_Cursor_isNull(result), detail::parse_error_handler{}, cur,
+                     "missing child of template");
+
+        auto entity = detail::parse_entity(context, result, true);
+        DEBUG_ASSERT(entity->kind() == EntityT::kind(), detail::parse_error_handler{}, cur,
+                     "wrong child of template");
+        return typename TemplateT::builder(
+            std::unique_ptr<EntityT>(static_cast<EntityT*>(entity.release())));
+    }
+
+    std::unique_ptr<cpp_template_parameter> parse_type_parameter(
+        const detail::parse_context& context, const CXCursor& cur)
+    {
+        DEBUG_ASSERT(clang_getCursorKind(cur) == CXCursor_TemplateTypeParameter,
+                     detail::assert_handler{});
+
+        detail::tokenizer    tokenizer(context.tu, context.file, cur);
+        detail::token_stream stream(tokenizer, cur);
+        auto                 name = detail::get_cursor_name(cur);
+
+        // syntax: typename/class [...] name [= ...]
+        auto keyword = cpp_template_keyword::keyword_class;
+        if (detail::skip_if(stream, "typename"))
+            keyword = cpp_template_keyword::keyword_typename;
+        else
+            detail::skip(stream, "class");
+
+        auto variadic = false;
+        if (detail::skip_if(stream, "..."))
+            variadic = true;
+
+        if (stream.peek() != "=")
+            detail::skip(stream, name.c_str());
+
+        std::unique_ptr<cpp_type> def;
+        if (detail::skip_if(stream, "="))
+            // default type
+            def = detail::parse_raw_type(context, stream, stream.end());
+
+        return cpp_template_type_parameter::build(*context.idx, detail::get_entity_id(cur),
+                                                  name.c_str(), keyword, variadic, std::move(def));
+    }
+
+    std::unique_ptr<cpp_template_parameter> parse_non_type_parameter(
+        const detail::parse_context& context, const CXCursor& cur)
+    {
+        DEBUG_ASSERT(clang_getCursorKind(cur) == CXCursor_NonTypeTemplateParameter,
+                     detail::assert_handler{});
+
+        auto name = detail::get_cursor_name(cur);
+        auto type = clang_getCursorType(cur);
+
+        std::unique_ptr<cpp_expression> def;
+        detail::visit_children(cur, [&](const CXCursor& child) {
+            DEBUG_ASSERT(clang_isExpression(clang_getCursorKind(child)) && !def,
+                         detail::parse_error_handler{}, cur,
+                         "unexpected child cursor of non type template parameter");
+            def = detail::parse_expression(context, child);
+        });
+
+        detail::tokenizer    tokenizer(context.tu, context.file, cur);
+        detail::token_stream stream(tokenizer, cur);
+
+        // see if it is variadic
+        // syntax a): some-tokens ... name some-tokens
+        // syntax b): some-tokens (some-tokens ... name) some-tokens-or-...
+        // name might be empty, so can't loop until it occurs
+        // some-tokens will not contain ... or parenthesis, however
+
+        auto is_variadic = false;
+        for (; !stream.done(); stream.bump())
+        {
+            if (stream.peek() == "...")
+            {
+                is_variadic = true;
+                break;
+            }
+            else if (stream.peek() == ")")
+                break;
+        }
+
+        return cpp_non_type_template_parameter::build(*context.idx, detail::get_entity_id(cur),
+                                                      name.c_str(),
+                                                      detail::parse_type(context, type),
+                                                      is_variadic, std::move(def));
+    }
+
+    std::unique_ptr<cpp_template_template_parameter> parse_template_parameter(
+        const detail::parse_context& context, const CXCursor& cur)
+    {
+        DEBUG_ASSERT(clang_getCursorKind(cur) == CXCursor_TemplateTemplateParameter,
+                     detail::assert_handler{});
+
+        detail::tokenizer    tokenizer(context.tu, context.file, cur);
+        detail::token_stream stream(tokenizer, cur);
+        auto                 name = detail::get_cursor_name(cur);
+
+        // syntax: template <…> class/typename [...] name [= …]
+        detail::skip(stream, "template");
+        detail::skip_brackets(stream);
+
+        auto keyword = cpp_template_keyword::keyword_class;
+        if (detail::skip_if(stream, "typename"))
+            keyword = cpp_template_keyword::keyword_typename;
+        else
+            detail::skip(stream, "class");
+
+        auto is_variadic = detail::skip_if(stream, "...");
+        detail::skip(stream, name.c_str());
+
+        // now we can create the builder
+        cpp_template_template_parameter::builder builder(name.c_str(), is_variadic);
+        builder.keyword(keyword);
+
+        // look for parameters and default
+        detail::visit_children(cur, [&](const CXCursor& child) {
+            auto kind = clang_getCursorKind(child);
+            if (kind == CXCursor_TemplateTypeParameter)
+                builder.add_parameter(parse_type_parameter(context, child));
+            else if (kind == CXCursor_NonTypeTemplateParameter)
+                builder.add_parameter(parse_non_type_parameter(context, child));
+            else if (kind == CXCursor_TemplateTemplateParameter)
+                builder.add_parameter(parse_template_parameter(context, child));
+            else if (kind == CXCursor_TemplateRef)
+            {
+                auto target = clang_getCursorReferenced(child);
+
+                // stream is after the keyword
+                // syntax: = default
+                detail::skip(stream, "=");
+
+                std::string spelling;
+                while (!stream.done())
+                    spelling += stream.get().c_str();
+                if (stream.unmunch())
+                {
+                    DEBUG_ASSERT(!spelling.empty() && spelling.back() == '>',
+                                 detail::assert_handler{});
+                    spelling.pop_back();
+                    DEBUG_ASSERT(!spelling.empty() && spelling.back() == '>',
+                                 detail::assert_handler{});
+                }
+
+                builder.default_template(
+                    cpp_template_ref(detail::get_entity_id(target), std::move(spelling)));
+            }
+            else
+                DEBUG_ASSERT(clang_isReference(kind), detail::parse_error_handler{}, cur,
+                             "unexpected child of template template parameter");
+        });
+
+        return builder.finish(*context.idx, detail::get_entity_id(cur));
+    }
+
+    template <class Builder>
+    void parse_parameters(Builder& builder, const detail::parse_context& context,
+                          const CXCursor& cur)
+    {
+        // now visit to get the parameters
+        detail::visit_children(cur, [&](const CXCursor& child) {
+            auto kind = clang_getCursorKind(child);
+            if (kind == CXCursor_TemplateTypeParameter)
+                builder.add_parameter(parse_type_parameter(context, child));
+            else if (kind == CXCursor_NonTypeTemplateParameter)
+                builder.add_parameter(parse_non_type_parameter(context, child));
+            else if (kind == CXCursor_TemplateTemplateParameter)
+                builder.add_parameter(parse_template_parameter(context, child));
+        });
+    }
+}
+
+std::unique_ptr<cpp_entity> detail::parse_cpp_alias_template(const detail::parse_context& context,
+                                                             const CXCursor&              cur)
+{
+    DEBUG_ASSERT(clang_getCursorKind(cur) == CXCursor_TypeAliasTemplateDecl,
+                 detail::assert_handler{});
+    auto builder = get_builder<cpp_alias_template, cpp_type_alias>(context, cur);
+    context.comments.match(builder.get(), cur);
+    parse_parameters(builder, context, cur);
+    return builder.finish(*context.idx, detail::get_entity_id(cur));
+}

src/libclang/tokenizer.cpp

@@ -80,14 +80,17 @@ namespace
     // this function returns the actual CXSourceRange that covers all parts required for parsing
     // might include more tokens
     // this function is the reason you shouldn't use libclang
-    CXSourceRange get_extent(const CXTranslationUnit& tu, const CXFile& file, const CXCursor& cur)
+    CXSourceRange get_extent(const CXTranslationUnit& tu, const CXFile& file, const CXCursor& cur,
+                             bool& unmunch)
     {
+        unmunch = false;
+
         auto extent = clang_getCursorExtent(cur);
         auto begin  = clang_getRangeStart(extent);
         auto end    = clang_getRangeEnd(extent);
 
-        if (cursor_is_function(clang_getCursorKind(cur))
+        auto kind = clang_getCursorKind(cur);
-            || cursor_is_function(clang_getTemplateCursorKind(cur)))
+        if (cursor_is_function(kind) || cursor_is_function(clang_getTemplateCursorKind(cur)))
         {
             auto range_shrunk = false;
 
@@ -114,24 +117,17 @@ namespace
                     end = get_next_location(tu, file, end);
                 } while (!token_after_is(tu, file, cur, end, ";"));
             }
-            else if (clang_getCursorKind(cur) == CXCursor_CXXMethod)
+            else if (kind == CXCursor_CXXMethod)
                 // necessary for some reason
                 begin = get_next_location(tu, file, begin, -1);
         }
-        else if (clang_getCursorKind(cur) == CXCursor_TemplateTypeParameter
+        else if (kind == CXCursor_TemplateTypeParameter && token_after_is(tu, file, cur, end, "("))
-                 || clang_getCursorKind(cur) == CXCursor_NonTypeTemplateParameter
-                 || clang_getCursorKind(cur) == CXCursor_TemplateTemplateParameter
-                 || clang_getCursorKind(cur) == CXCursor_ParmDecl)
-        {
-            if (clang_getCursorKind(cur) == CXCursor_TemplateTypeParameter
-                && token_after_is(tu, file, cur, end, "("))
         {
             // if you have decltype as default argument for a type template parameter
             // libclang doesn't include the parameters
             auto next = get_next_location(tu, file, end);
             auto prev = end;
-                for (auto paren_count = 1; paren_count != 0;
+            for (auto paren_count = 1; paren_count != 0; next = get_next_location(tu, file, next))
-                     next             = get_next_location(tu, file, next))
             {
                 if (token_after_is(tu, file, cur, next, "("))
                     ++paren_count;
@@ -141,10 +137,49 @@ namespace
             }
             end = prev;
         }
+        else if (kind == CXCursor_TemplateTemplateParameter
+                 && token_after_is(tu, file, cur, end, "<"))
+        {
+            // if you have a template template parameter in a template template parameter,
+            // the tokens are all messed up, only contain the `template`
+
+            // first: skip to closing angle bracket
+            // luckily no need to handle expressions here
+            auto next = get_next_location(tu, file, end, 2);
+            for (auto angle_count = 1; angle_count != 0; next = get_next_location(tu, file, next))
+            {
+                if (token_after_is(tu, file, cur, next, ">"))
+                    --angle_count;
+                else if (token_after_is(tu, file, cur, next, ">>"))
+                    angle_count -= 2;
+                else if (token_after_is(tu, file, cur, next, "<"))
+                    ++angle_count;
             }
-        else if (clang_isExpression(clang_getCursorKind(cur))
+
-                 || clang_getCursorKind(cur) == CXCursor_CXXBaseSpecifier
+            // second: skip until end of parameter
-                 || clang_getCursorKind(cur) == CXCursor_FieldDecl)
+            // no need to handle default, so look for '>' or ','
+            while (!token_after_is(tu, file, cur, next, ">")
+                   && !token_after_is(tu, file, cur, next, ","))
+                next = get_next_location(tu, file, next);
+            // now we found the proper end of the token
+            end = get_next_location(tu, file, next, -1);
+        }
+        else if ((kind == CXCursor_TemplateTypeParameter
+                  || kind == CXCursor_NonTypeTemplateParameter
+                  || kind == CXCursor_TemplateTemplateParameter)
+                 && !token_after_is(tu, file, cur, end, ">")
+                 && !token_after_is(tu, file, cur, end, ","))
+        {
+            DEBUG_ASSERT(token_after_is(tu, file, cur, get_next_location(tu, file, end, -2), ">>"),
+                         detail::assert_handler{});
+            unmunch = true;
+            // need to shrink range anyway
+            end = get_next_location(tu, file, end, -1);
+        }
+        else if (clang_isExpression(kind) || kind == CXCursor_CXXBaseSpecifier
+                 || kind == CXCursor_FieldDecl || kind == CXCursor_TemplateTypeParameter
+                 || kind == CXCursor_NonTypeTemplateParameter
+                 || kind == CXCursor_TemplateTemplateParameter)
             // need to shrink range by one
             end = get_next_location(tu, file, end, -1);
 
@@ -154,7 +189,7 @@ namespace
 
 detail::tokenizer::tokenizer(const CXTranslationUnit& tu, const CXFile& file, const CXCursor& cur)
 {
-    auto extent = get_extent(tu, file, cur);
+    auto extent = get_extent(tu, file, cur, unmunch_);
 
     simple_tokenizer tokenizer(tu, extent, cur);
     tokens_.reserve(tokenizer.size());
@@ -164,10 +199,14 @@ detail::tokenizer::tokenizer(const CXTranslationUnit& tu, const CXFile& file, co
 
 void detail::skip(detail::token_stream& stream, const char* str)
 {
+    if (*str)
+    {
+        // non-empty
         auto& token = stream.peek();
         DEBUG_ASSERT(token == str, parse_error_handler{}, stream.cursor(),
                      format("expected '", str, "', got '", token.c_str(), "'"));
         stream.bump();
+    }
 }
 
 namespace
@@ -185,6 +224,8 @@ namespace
 
 bool detail::skip_if(detail::token_stream& stream, const char* str, bool multi_token)
 {
+    if (!*str)
+        return true;
     auto save = stream.cur();
     do
     {
@@ -212,7 +253,7 @@ detail::token_iterator detail::find_closing_bracket(detail::token_stream stream)
         close_bracket = "]";
     else if (skip_if(stream, "<"))
     {
-        close_bracket    = "<";
+        close_bracket    = ">";
         template_bracket = true;
     }
     else

src/libclang/tokenizer.hpp

@@ -76,15 +76,28 @@ namespace cppast
                 return tokens_.end();
             }
 
+            // if it returns true, the last token is ">>",
+            // but should haven been ">"
+            // only a problem for template parameters
+            bool unmunch() const noexcept
+            {
+                return unmunch_;
+            }
+
         private:
             std::vector<token> tokens_;
+            bool               unmunch_;
         };
 
         class token_stream
         {
         public:
             explicit token_stream(const tokenizer& tokenizer, const CXCursor& cur)
-            : cursor_(cur), begin_(tokenizer.begin()), cur_(begin_), end_(tokenizer.end())
+            : cursor_(cur),
+              begin_(tokenizer.begin()),
+              cur_(begin_),
+              end_(tokenizer.end()),
+              unmunch_(tokenizer.unmunch())
             {
             }
 
@@ -144,9 +157,15 @@ namespace cppast
                 cur_ = iter;
             }
 
+            bool unmunch() const noexcept
+            {
+                return unmunch_;
+            }
+
         private:
             CXCursor       cursor_;
             token_iterator begin_, cur_, end_;
+            bool           unmunch_;
         };
 
         // skips the next token

src/libclang/type_parser.cpp

@@ -435,16 +435,51 @@ std::unique_ptr<cpp_type> detail::parse_type(const detail::parse_context& contex
     return std::move(result);
 }
 
+namespace
+{
+    bool is_identifier(char c)
+    {
+        return std::isalnum(c) || c == '_';
+    }
+}
+
+std::unique_ptr<cpp_type> detail::parse_raw_type(const detail::parse_context&,
+                                                 detail::token_stream&  stream,
+                                                 detail::token_iterator end)
+{
+    std::string result;
+    while (stream.cur() != end)
+    {
+        auto& token = stream.get();
+        if (!result.empty() && is_identifier(result.back()) && is_identifier(token.value()[0u]))
+            result += ' ';
+        result += token.c_str();
+    }
+    if (stream.unmunch())
+    {
+        DEBUG_ASSERT(!result.empty() && result.back() == '>', detail::assert_handler{});
+        result.pop_back();
+        DEBUG_ASSERT(!result.empty() && result.back() == '>', detail::assert_handler{});
+    }
+    return cpp_unexposed_type::build(std::move(result));
+}
+
 std::unique_ptr<cpp_entity> detail::parse_cpp_type_alias(const detail::parse_context& context,
-                                                         const CXCursor&              cur)
+                                                         const CXCursor& cur, bool as_template)
 {
     DEBUG_ASSERT(cur.kind == CXCursor_TypeAliasDecl || cur.kind == CXCursor_TypedefDecl,
                  detail::assert_handler{});
 
     auto name = detail::get_cursor_name(cur);
     auto type = parse_type(context, clang_getTypedefDeclUnderlyingType(cur));
+
+    if (as_template)
+        return cpp_type_alias::build(name.c_str(), std::move(type));
+    else
+    {
         auto result =
             cpp_type_alias::build(*context.idx, get_entity_id(cur), name.c_str(), std::move(type));
         context.comments.match(*result, cur);
         return result;
+    }
 }

test/cpp_template_parameter.cpp

@@ -0,0 +1,291 @@
+// 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_template_parameter.hpp>
+
+#include <cppast/cpp_alias_template.hpp>
+#include <cppast/cpp_function_type.hpp>
+
+#include "test_parser.hpp"
+
+using namespace cppast;
+
+TEST_CASE("cpp_template_type_parameter")
+{
+    auto code = R"(
+
+template <typename A>
+using a = void;
+
+template <class ... B>
+using b = void;
+
+template <typename = const int*>
+using c = void;
+
+// libclang workaround when decltype here
+template <class D = decltype(1 + 3)>
+using d = void;
+
+// maximal munch here
+template <typename E = a<void>>
+using e = void;
+)";
+
+    cpp_entity_index idx;
+    auto             file = parse(idx, "cpp_template_type_parameter.cpp", code);
+    auto count = test_visit<cpp_alias_template>(*file, [&](const cpp_alias_template& alias) {
+        REQUIRE(equal_types(idx, alias.type_alias().underlying_type(),
+                            *cpp_builtin_type::build("void")));
+
+        for (auto& p : alias.parameters())
+        {
+            REQUIRE(p.kind() == cpp_entity_kind::template_type_parameter_t);
+
+            auto& param = static_cast<const cpp_template_type_parameter&>(p);
+            if (param.name() == "A")
+            {
+                REQUIRE(alias.name() == "a");
+                REQUIRE(param.keyword() == cpp_template_keyword::keyword_typename);
+                REQUIRE(!param.is_variadic());
+                REQUIRE(!param.default_type());
+            }
+            else if (param.name() == "B")
+            {
+                REQUIRE(alias.name() == "b");
+                REQUIRE(param.keyword() == cpp_template_keyword::keyword_class);
+                REQUIRE(param.is_variadic());
+                REQUIRE(!param.default_type());
+            }
+            else if (param.name() == "")
+            {
+                REQUIRE(alias.name() == "c");
+                REQUIRE(param.keyword() == cpp_template_keyword::keyword_typename);
+                REQUIRE(!param.is_variadic());
+                REQUIRE(param.default_type().has_value());
+                REQUIRE(equal_types(idx, param.default_type().value(),
+                                    *cpp_unexposed_type::build("const int*")));
+            }
+            else if (param.name() == "D")
+            {
+                REQUIRE(alias.name() == "d");
+                REQUIRE(param.keyword() == cpp_template_keyword::keyword_class);
+                REQUIRE(!param.is_variadic());
+                REQUIRE(param.default_type().has_value());
+                REQUIRE(equal_types(idx, param.default_type().value(),
+                                    *cpp_unexposed_type::build("decltype(1+3)")));
+            }
+            else if (param.name() == "E")
+            {
+                REQUIRE(alias.name() == "e");
+                REQUIRE(param.keyword() == cpp_template_keyword::keyword_typename);
+                REQUIRE(!param.is_variadic());
+                REQUIRE(param.default_type().has_value());
+                REQUIRE(equal_types(idx, param.default_type().value(),
+                                    *cpp_unexposed_type::build("a<void>")));
+            }
+            else
+                REQUIRE(false);
+        }
+    });
+    REQUIRE(count == 5u);
+}
+
+TEST_CASE("cpp_non_type_template_parameter")
+{
+    auto code = R"(
+template <int A>
+using a = void;
+
+template <char* = nullptr>
+using b = void;
+
+template <int ... C>
+using c = void;
+
+template <void(* D)(...)>
+using d = void;
+)";
+
+    cpp_entity_index idx;
+    auto             file = parse(idx, "cpp_non_type_template_parameter.cpp", code);
+    auto count = test_visit<cpp_alias_template>(*file, [&](const cpp_alias_template& alias) {
+        REQUIRE(equal_types(idx, alias.type_alias().underlying_type(),
+                            *cpp_builtin_type::build("void")));
+
+        for (auto& p : alias.parameters())
+        {
+            REQUIRE(p.kind() == cpp_entity_kind::non_type_template_parameter_t);
+
+            auto& param = static_cast<const cpp_non_type_template_parameter&>(p);
+            if (param.name() == "A")
+            {
+                REQUIRE(alias.name() == "a");
+                REQUIRE(equal_types(idx, param.type(), *cpp_builtin_type::build("int")));
+                REQUIRE(!param.is_variadic());
+                REQUIRE(!param.default_value());
+            }
+            else if (param.name() == "")
+            {
+                REQUIRE(alias.name() == "b");
+                REQUIRE(equal_types(idx, param.type(),
+                                    *cpp_pointer_type::build(cpp_builtin_type::build("char"))));
+                REQUIRE(!param.is_variadic());
+                REQUIRE(param.default_value());
+                REQUIRE(equal_expressions(param.default_value().value(),
+                                          *cpp_literal_expression::build(cpp_builtin_type::build(
+                                                                             "nullptr_t"),
+                                                                         "nullptr")));
+            }
+            else if (param.name() == "C")
+            {
+                REQUIRE(alias.name() == "c");
+                REQUIRE(equal_types(idx, param.type(), *cpp_builtin_type::build("int")));
+                REQUIRE(param.is_variadic());
+                REQUIRE(!param.default_value());
+            }
+            else if (param.name() == "D")
+            {
+                REQUIRE(alias.name() == "d");
+
+                cpp_function_type::builder builder(cpp_builtin_type::build("void"));
+                builder.is_variadic();
+                REQUIRE(equal_types(idx, param.type(), *cpp_pointer_type::build(builder.finish())));
+
+                REQUIRE(!param.is_variadic());
+                REQUIRE(!param.default_value());
+            }
+            else
+                REQUIRE(false);
+        }
+    });
+    REQUIRE(count == 4u);
+}
+
+TEST_CASE("cpp_template_template_parameter")
+{
+    // no need to check parameters of template parameter
+    auto code = R"(
+namespace ns
+{
+    template <int I>
+    using def = void;
+}
+
+template <template <typename T> class A>
+using a = void;
+
+template <template <int, typename> class ... B>
+using b = void;
+
+template <template <int> class C = ns::def>
+using c = void;
+
+template <template <template <typename> class> class D = a>
+using d = void;
+)";
+
+    cpp_entity_index idx;
+    auto             file = parse(idx, "cpp_template_template_parameter.cpp", code);
+    auto count = test_visit<cpp_alias_template>(*file, [&](const cpp_alias_template& alias) {
+        REQUIRE(equal_types(idx, alias.type_alias().underlying_type(),
+                            *cpp_builtin_type::build("void")));
+        if (alias.name() == "def")
+            return;
+
+        for (auto& p : alias.parameters())
+        {
+            REQUIRE(p.kind() == cpp_entity_kind::template_template_parameter_t);
+
+            auto& param = static_cast<const cpp_template_template_parameter&>(p);
+            REQUIRE(param.keyword() == cpp_template_keyword::keyword_class);
+            if (param.name() == "A")
+            {
+                REQUIRE(alias.name() == "a");
+                REQUIRE(!param.is_variadic());
+                REQUIRE(!param.default_template());
+
+                auto no = 0u;
+                for (auto& p_param : param)
+                {
+                    ++no;
+                    REQUIRE(p_param.name() == "T");
+                    REQUIRE(p_param.kind() == cpp_entity_kind::template_type_parameter_t);
+                }
+                REQUIRE(no == 1u);
+            }
+            else if (param.name() == "B")
+            {
+                REQUIRE(alias.name() == "b");
+                REQUIRE(param.is_variadic());
+                REQUIRE(!param.default_template());
+
+                auto cur = param.begin();
+                REQUIRE(cur != param.end());
+                REQUIRE(cur->name().empty());
+                REQUIRE(cur->kind() == cpp_entity_kind::non_type_template_parameter_t);
+
+                ++cur;
+                REQUIRE(cur != param.end());
+                REQUIRE(cur->name().empty());
+                REQUIRE(cur->kind() == cpp_entity_kind::template_type_parameter_t);
+
+                ++cur;
+                REQUIRE(cur == param.end());
+            }
+            else if (param.name() == "C")
+            {
+                REQUIRE(alias.name() == "c");
+                REQUIRE(!param.is_variadic());
+                REQUIRE(param.default_template());
+
+                auto def = param.default_template().value();
+                REQUIRE(def.name() == "ns::def");
+                auto entities = def.get(idx);
+                REQUIRE(entities.size() == 1u);
+                REQUIRE(entities[0]->name() == "def");
+
+                auto no = 0u;
+                for (auto& p_param : param)
+                {
+                    ++no;
+                    REQUIRE(p_param.name() == "");
+                    REQUIRE(p_param.kind() == cpp_entity_kind::non_type_template_parameter_t);
+                }
+                REQUIRE(no == 1u);
+            }
+            else if (param.name() == "D")
+            {
+                REQUIRE(alias.name() == "d");
+                REQUIRE(!param.is_variadic());
+                REQUIRE(param.default_template());
+
+                auto def = param.default_template().value();
+                REQUIRE(def.name() == "a");
+                auto entities = def.get(idx);
+                REQUIRE(entities.size() == 1u);
+                REQUIRE(entities[0]->name() == "a");
+
+                auto no = 0u;
+                for (auto& p_param : param)
+                {
+                    ++no;
+                    REQUIRE(p_param.name() == "");
+                    REQUIRE(p_param.kind() == cpp_entity_kind::template_template_parameter_t);
+                    for (auto& p_p_param :
+                         static_cast<const cpp_template_template_parameter&>(p_param))
+                    {
+                        ++no;
+                        REQUIRE(p_p_param.name() == "");
+                        REQUIRE(p_p_param.kind() == cpp_entity_kind::template_type_parameter_t);
+                    }
+                }
+                REQUIRE(no == 2u);
+            }
+            else
+                REQUIRE(false);
+        }
+    });
+    REQUIRE(count == 5u);
+}