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connection_create_aggregate.impl.hpp
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connection_create_aggregate.impl.hpp
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// Implementation of connection::create_aggregate()
#if !defined(SQXX_CONNECTION_CREATE_AGGREGATE_IMPL_HPP_INCLUDED)
#define SQXX_CONNECTION_CREATE_AGGREGATE_IMPL_HPP_INCLUDED
// Function types with C calling convention for callbacks
// https://stackoverflow.com/a/5590050/
extern "C" typedef void sqxx_aggregate_step_type(sqlite3_context*, int, sqlite3_value**);
extern "C" typedef void sqxx_aggregate_final_type(sqlite3_context*);
namespace sqxx {
namespace detail {
// Data associated with an aggregate
template<typename StateD>
struct aggregate_invocation_data {
bool initialized;
StateD state;
aggregate_invocation_data(const StateD &zero) : initialized(true), state(zero) {
}
};
template<typename StateD, typename StepD, typename FinalD>
class aggregate_data {
private:
const StateD state_zero;
StepD stepfun;
FinalD finalfun;
static constexpr int NArgs = callable_traits<StepD>::argc - 1;
public:
template<typename State, typename StepFun, typename FinalFun>
aggregate_data(State &&state_zero_arg, StepFun &&stepfun_arg, FinalFun &&finalfun_arg)
: state_zero(std::forward<State>(state_zero_arg)), stepfun(std::forward<StepFun>(stepfun_arg)), finalfun(std::forward<FinalFun>(finalfun_arg)) {
}
private:
typedef aggregate_invocation_data<StateD> invocation_data;
// Returns the aggregation state, creating it if it doesn't exist yet.
invocation_data* get_state_create(context &ctx) {
invocation_data *as = reinterpret_cast<invocation_data*>(
ctx.aggregate_context(sizeof(invocation_data))
);
if (!as) {
throw std::bad_alloc();
}
// Sqlite zeros freshly allocated memory, so `as->initialized` will
// start out as `false` if we haven't called the constructor yet.
if (!as->initialized) {
// Construct object, with a state copied from `state_zero`
new(as) invocation_data(state_zero);
}
return as;
}
// Returns the aggregation state, if there is any
invocation_data* get_state_existing(context &ctx) {
// Calling with size 0. We'll get any existing data, or a nullptr if
// there isn't any.
invocation_data *as = reinterpret_cast<invocation_data*>(
ctx.aggregate_context(0)
);
return as;
}
public:
void step_call(context &ctx, int argc, sqlite3_value **values) {
if (argc != NArgs) {
ctx.result_error_misuse();
return;
}
invocation_data *as = get_state_create(ctx);
apply_value_array<NArgs, void>(stepfun, values, as->state);
//std::vector<value> vs(values, values+nargs);
}
void final_call(context &ctx) {
// Take ownership of state (if any), deleting it on return
ownedobj_ptr<invocation_data> as(get_state_existing(ctx));
if (as) {
// We have state
ctx.result(finalfun(as->state));
}
else {
// There was no allocated state
ctx.result(finalfun(state_zero));
}
}
};
template<typename StateD, typename StepD, typename FinalD>
sqxx_aggregate_step_type aggregate_call_step;
template<typename StateD, typename StepD, typename FinalD>
void aggregate_call_step(sqlite3_context *handle, int argc, sqlite3_value** argv) {
typedef aggregate_data<StateD, StepD, FinalD> data_t;
data_t *data = reinterpret_cast<data_t*>(sqlite3_user_data(handle));
context ctx(handle);
try {
data->step_call(ctx, argc, argv);
}
catch (const error &e) {
ctx.result_error_code(e.code);
}
catch (const std::bad_alloc &) {
ctx.result_error_nomem();
}
catch (const std::exception &e) {
ctx.result_error(e.what());
}
catch (...) {
ctx.result_error_misuse();
}
}
template<typename StateD, typename StepD, typename FinalD>
sqxx_aggregate_final_type aggregate_call_final;
template<typename StateD, typename StepD, typename FinalD>
void aggregate_call_final(sqlite3_context *handle) {
typedef aggregate_data<StateD, StepD, FinalD> data_t;
data_t *data = reinterpret_cast<data_t*>(sqlite3_user_data(handle));
context ctx(handle);
try {
data->final_call(ctx);
}
catch (const error &e) {
ctx.result_error_code(e.code);
}
catch (const std::bad_alloc &) {
ctx.result_error_nomem();
}
catch (const std::exception &e) {
ctx.result_error(e.what());
}
catch (...) {
ctx.result_error_misuse();
}
}
void create_aggregate_register(sqlite3 *handle, const char *name, int nargs, void *data,
sqxx_aggregate_step_type *stepfun, sqxx_aggregate_final_type *finalfun,
sqxx_appdata_destroy_type *destroy);
} // namespace detail
template<typename State, typename StepCallable, typename FinalCallable>
void connection::create_aggregate(const char *name,
State &&zero,
StepCallable &&stepfun,
FinalCallable &&finalfun) {
typedef std::decay_t<State> StateD;
typedef std::decay_t<StepCallable> StepD;
typedef std::decay_t<FinalCallable> FinalD;
typedef callable_traits<StepD> traits;
typedef detail::aggregate_data<StateD, StepD, FinalD> data_t;
data_t *adat = new data_t(
std::forward<State>(zero),
std::forward<StepCallable>(stepfun),
std::forward<FinalCallable>(finalfun)
);
detail::create_aggregate_register(handle, name, traits::argc-1, reinterpret_cast<void*>(adat),
detail::aggregate_call_step<StateD, StepD, FinalD>,
detail::aggregate_call_final<StateD, StepD, FinalD>,
detail::appdata_destroy_object<data_t>);
}
template<typename State, typename StepCallable, typename FinalCallable>
void connection::create_aggregate(const std::string &name, State &&zero,
StepCallable &&step_fun, FinalCallable &&final_fun) {
create_aggregate(name.c_str(), std::forward<State>(zero), std::forward<StepCallable>(step_fun),
std::forward<FinalCallable>(final_fun));
}
template<typename State, typename StepCallable>
void connection::create_aggregate(const char *name, State &&zero, StepCallable &&step_fun) {
create_aggregate<State, StepCallable>(name, std::forward<State>(zero),
std::forward<StepCallable>(step_fun),
[](const State &state) -> State { return state; }
);
}
template<typename State, typename StepCallable>
void connection::create_aggregate(const std::string &name, State &&zero, StepCallable &&step_fun) {
create_aggregate(name.c_str(), std::forward<State>(zero), std::forward<StepCallable>(step_fun));
}
} // namespace sqxx
#endif // SQXX_CONNECTION_CREATE_AGGREGATE_IMPL_HPP_INCLUDED