From e5275e30efc1a4f991fd6bd087bcf643a119a515 Mon Sep 17 00:00:00 2001
From: Kevin Xu <kevin.xu001@yahoo.com>
Date: Mon, 6 Dec 2021 15:23:45 -0500
Subject: [PATCH] make LexerType template arg

---
 include/nlohmann/detail/input/parser.hpp | 4 ++--
 include/nlohmann/detail/macro_scope.hpp  | 5 +++--
 include/nlohmann/json.hpp                | 6 +++---
 include/nlohmann/json_fwd.hpp            | 9 ++++++++-
 4 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/include/nlohmann/detail/input/parser.hpp b/include/nlohmann/detail/input/parser.hpp
index 99cdd05ec..70ea6cdb7 100644
--- a/include/nlohmann/detail/input/parser.hpp
+++ b/include/nlohmann/detail/input/parser.hpp
@@ -48,14 +48,14 @@ using parser_callback_t =
 
 This class implements a recursive descent parser.
 */
-template<typename BasicJsonType, typename InputAdapterType>
+template<template<typename, typename> class LexerType, typename BasicJsonType, typename InputAdapterType>
 class parser
 {
     using number_integer_t = typename BasicJsonType::number_integer_t;
     using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
     using number_float_t = typename BasicJsonType::number_float_t;
     using string_t = typename BasicJsonType::string_t;
-    using lexer_t = lexer<BasicJsonType, InputAdapterType>;
+    using lexer_t = LexerType<BasicJsonType, InputAdapterType>;
     using token_type = typename lexer_t::token_type;
 
   public:
diff --git a/include/nlohmann/detail/macro_scope.hpp b/include/nlohmann/detail/macro_scope.hpp
index c2a65bdda..ee5519b76 100644
--- a/include/nlohmann/detail/macro_scope.hpp
+++ b/include/nlohmann/detail/macro_scope.hpp
@@ -132,12 +132,13 @@
              class NumberUnsignedType, class NumberFloatType,              \
              template<typename> class AllocatorType,                       \
              template<typename, typename = void> class JSONSerializer,     \
-             class BinaryType>
+             class BinaryType,                                             \
+             template<typename, typename> class LexerType>
 
 #define NLOHMANN_BASIC_JSON_TPL                                            \
     basic_json<ObjectType, ArrayType, StringType, BooleanType,             \
     NumberIntegerType, NumberUnsignedType, NumberFloatType,                \
-    AllocatorType, JSONSerializer, BinaryType>
+    AllocatorType, JSONSerializer, BinaryType, LexerType>
 
 // Macros to simplify conversion from/to types
 
diff --git a/include/nlohmann/json.hpp b/include/nlohmann/json.hpp
index 7ea86c38c..318da5e28 100644
--- a/include/nlohmann/json.hpp
+++ b/include/nlohmann/json.hpp
@@ -199,17 +199,17 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
 
   JSON_PRIVATE_UNLESS_TESTED:
     // convenience aliases for types residing in namespace detail;
-    using lexer = ::nlohmann::detail::lexer_base<basic_json>;
+    // using lexer = ::nlohmann::detail::lexer_base<basic_json>;
 
     template<typename InputAdapterType>
-    static ::nlohmann::detail::parser<basic_json, InputAdapterType> parser(
+    static ::nlohmann::detail::parser<LexerType, basic_json, InputAdapterType> parser(
         InputAdapterType adapter,
         detail::parser_callback_t<basic_json>cb = nullptr,
         const bool allow_exceptions = true,
         const bool ignore_comments = false
     )
     {
-        return ::nlohmann::detail::parser<basic_json, InputAdapterType>(std::move(adapter),
+        return ::nlohmann::detail::parser<LexerType, basic_json, InputAdapterType>(std::move(adapter),
                 std::move(cb), allow_exceptions, ignore_comments);
     }
 
diff --git a/include/nlohmann/json_fwd.hpp b/include/nlohmann/json_fwd.hpp
index 332227c1b..dead19b0d 100644
--- a/include/nlohmann/json_fwd.hpp
+++ b/include/nlohmann/json_fwd.hpp
@@ -24,6 +24,12 @@ for serialization.
 template<typename T = void, typename SFINAE = void>
 struct adl_serializer;
 
+namespace detail
+{
+template<typename BasicJsonType, typename InputAdapterType>
+class lexer;
+}
+
 template<template<typename U, typename V, typename... Args> class ObjectType =
          std::map,
          template<typename U, typename... Args> class ArrayType = std::vector,
@@ -34,7 +40,8 @@ template<template<typename U, typename V, typename... Args> class ObjectType =
          template<typename U> class AllocatorType = std::allocator,
          template<typename T, typename SFINAE = void> class JSONSerializer =
          adl_serializer,
-         class BinaryType = std::vector<std::uint8_t>>
+         class BinaryType = std::vector<std::uint8_t>,
+         template<typename BasicJsonType, typename InputAdapterType> class LexerType = detail::lexer>
 class basic_json;
 
 /*!