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mdbx++: добавление cursor::scan(predicate...) и т.п.

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This commit is contained in:
Леонид Юрьев (Leonid Yuriev)
2023-11-20 21:22:36 +03:00
parent 4999264460
commit 0b68980489
1 changed files with 83 additions and 0 deletions
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83
mdbx.h++
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@@ -4457,6 +4457,89 @@ protected:
MDBX_val *value) const;
public:
template <typename CALLABLE_PREDICATE>
bool scan(CALLABLE_PREDICATE predicate, move_operation start = first,
move_operation turn = next) {
struct wrapper : public exception_thunk {
static int probe(void *context, MDBX_val *key, MDBX_val *value,
void *arg) noexcept {
auto thunk = static_cast<wrapper *>(context);
assert(thunk->is_clean());
auto &predicate = *static_cast<CALLABLE_PREDICATE *>(arg);
try {
return predicate(pair(*key, *value)) ? MDBX_RESULT_TRUE
: MDBX_RESULT_FALSE;
} catch (... /* capture any exception to rethrow it over C code */) {
thunk->capture();
return MDBX_RESULT_TRUE;
}
}
} thunk;
return error::boolean_or_throw(
::mdbx_cursor_scan(handle_, wrapper::probe, &thunk,
MDBX_cursor_op(start), MDBX_cursor_op(turn),
&predicate),
thunk);
}
template <typename CALLABLE_PREDICATE>
bool fullscan(CALLABLE_PREDICATE predicate, bool backward = false) {
return scan(std::move(predicate), backward ? last : first,
backward ? previous : next);
}
template <typename CALLABLE_PREDICATE>
bool scan_from(CALLABLE_PREDICATE predicate, slice &from,
move_operation start = key_greater_or_equal,
move_operation turn = next) {
struct wrapper : public exception_thunk {
static int probe(void *context, MDBX_val *key, MDBX_val *value,
void *arg) noexcept {
auto thunk = static_cast<wrapper *>(context);
assert(thunk->is_clean());
auto &predicate = *static_cast<CALLABLE_PREDICATE *>(arg);
try {
return predicate(pair(*key, *value)) ? MDBX_RESULT_TRUE
: MDBX_RESULT_FALSE;
} catch (... /* capture any exception to rethrow it over C code */) {
thunk->capture();
return MDBX_RESULT_TRUE;
}
}
} thunk;
return error::boolean_or_throw(
::mdbx_cursor_scan_from(handle_, wrapper::probe, &thunk,
MDBX_cursor_op(start), &from, nullptr,
MDBX_cursor_op(turn), &predicate),
thunk);
}
template <typename CALLABLE_PREDICATE>
bool scan_from(CALLABLE_PREDICATE predicate, pair &from,
move_operation start = pair_greater_or_equal,
move_operation turn = next) {
struct wrapper : public exception_thunk {
static int probe(void *context, MDBX_val *key, MDBX_val *value,
void *arg) noexcept {
auto thunk = static_cast<wrapper *>(context);
assert(thunk->is_clean());
auto &predicate = *static_cast<CALLABLE_PREDICATE *>(arg);
try {
return predicate(pair(*key, *value)) ? MDBX_RESULT_TRUE
: MDBX_RESULT_FALSE;
} catch (... /* capture any exception to rethrow it over C code */) {
thunk->capture();
return MDBX_RESULT_TRUE;
}
}
} thunk;
return error::boolean_or_throw(
::mdbx_cursor_scan_from(handle_, wrapper::probe, &thunk,
MDBX_cursor_op(start), &from.key, &from.value,
MDBX_cursor_op(turn), &predicate),
thunk);
}
move_result move(move_operation operation, bool throw_notfound) {
return move_result(*this, operation, throw_notfound);
}