diff options
Diffstat (limited to 'indra/llcommon/llsdutil.h')
| -rw-r--r-- | indra/llcommon/llsdutil.h | 49 |
1 files changed, 22 insertions, 27 deletions
diff --git a/indra/llcommon/llsdutil.h b/indra/llcommon/llsdutil.h index eddaa64bd2..546e27930d 100644 --- a/indra/llcommon/llsdutil.h +++ b/indra/llcommon/llsdutil.h @@ -29,10 +29,12 @@ #ifndef LL_LLSDUTIL_H #define LL_LLSDUTIL_H +#include "apply.h" // LL::invoke() #include "llsd.h" #include <boost/functional/hash.hpp> -#include <boost/type_traits.hpp> +#include <boost/function_types/function_arity.hpp> #include <cassert> +#include <type_traits> // U32 LL_COMMON_API LLSD ll_sd_from_U32(const U32); @@ -589,6 +591,10 @@ namespace LL /***************************************************************************** * apply(function, LLSD array) *****************************************************************************/ +// validate incoming LLSD blob, and return an LLSD array suitable to pass to +// apply_impl() +LLSD apply_llsd_fix(size_t arity, const LLSD& args); + // Derived from https://stackoverflow.com/a/20441189 // and https://en.cppreference.com/w/cpp/utility/apply . // We can't simply make a tuple from the LLSD array and then apply() that @@ -602,6 +608,16 @@ auto apply_impl(CALLABLE&& func, const LLSD& array, std::index_sequence<I...>) return std::forward<CALLABLE>(func)(LLSDParam<LLSD>(array[I])...); } +// use apply_n<ARITY>(function, LLSD) to call a specific arity of a variadic +// function with (that many) items from the passed LLSD array +template <size_t ARITY, typename CALLABLE> +auto apply_n(CALLABLE&& func, const LLSD& args) +{ + return apply_impl(std::forward<CALLABLE>(func), + apply_llsd_fix(ARITY, args), + std::make_index_sequence<ARITY>()); +} + /** * apply(function, LLSD) goes beyond C++17 std::apply(). For this case * @a function @emph cannot be variadic: the compiler must know at compile @@ -610,32 +626,11 @@ auto apply_impl(CALLABLE&& func, const LLSD& array, std::index_sequence<I...>) template <typename CALLABLE> auto apply(CALLABLE&& func, const LLSD& args) { - LLSD array; - constexpr auto arity = boost::function_traits<CALLABLE>::arity; - // LLSD supports a number of types, two of which are aggregates: Map and - // Array. We don't try to support Map: supporting Map would seem to - // promise that we could somehow match the string key to 'func's parameter - // names. Uh sorry, maybe in some future version of C++ with reflection. - assert(! args.isMap()); - // We expect an LLSD array, but what the heck, treat isUndefined() as a - // zero-length array for calling a nullary 'func'. - if (args.isUndefined() || args.isArray()) - { - // this works because LLSD().size() == 0 - assert(args.size() == arity); - array = args; - } - else // args is one of the scalar types - { - // scalar_LLSD.size() == 0, so don't test that here. - // You can pass a scalar LLSD only to a unary 'func'. - assert(arity == 1); - // make an array of it - array = llsd::array(args); - } - return apply_impl(std::forward<CALLABLE>(func), - array, - std::make_index_sequence<arity>()); + // infer arity from the definition of func + constexpr auto arity = boost::function_types::function_arity< + typename std::remove_reference<CALLABLE>::type>::value; + // now that we have a compile-time arity, apply_n() works + return apply_n<arity>(std::forward<CALLABLE>(func), args); } } // namespace LL |