arg-packs.h
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// See www.openfst.org for extensive documentation on this weighted
// finite-state transducer library.
//
// std::pair and std::tuple are used for the arguments of FstClass operations.
//
// If a function with a return value is required, use the WithReturnValue
// template as follows:
//
// WithReturnValue<bool, std::tuple<...>>
#ifndef FST_SCRIPT_ARG_PACKS_H_
#define FST_SCRIPT_ARG_PACKS_H_
#include <type_traits>
namespace fst {
namespace script {
// Tack this on to an existing type to add a return value. The syntax for
// accessing the args is then slightly more stilted, as you must do an extra
// member access (since the args are stored as a member of this class).
template <class Retval, class ArgTuple>
struct WithReturnValue {
// Avoid reference-to-reference if ArgTuple is a reference.
using Args = typename std::remove_reference<ArgTuple>::type;
Retval retval;
const Args &args;
explicit WithReturnValue(const Args &args) : args(args) {}
};
} // namespace script
} // namespace fst
#endif // FST_SCRIPT_ARG_PACKS_H_