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Add RAII-based event_queue_peeker_t helper

This is a stack-allocating utility class to peek up to N
characters/events out of an `event_queue_t` object. The need for a
hard-coded maximum peek length N at each call site is to avoid any heap
allocation, as this would be called in a hot path on every input event.
This commit is contained in:
Mahmoud Al-Qudsi 2021-02-06 17:11:05 -06:00
parent c203c88c66
commit cc392b3774
2 changed files with 55 additions and 0 deletions

View file

@ -467,6 +467,48 @@ maybe_t<input_mapping_t> inputter_t::find_mapping() {
return generic ? maybe_t<input_mapping_t>(*generic) : none();
}
template <size_t N = 16>
class event_queue_peeker_t {
private:
input_event_queue_t &event_queue_;
std::array<char_event_t, N> peeked_;
size_t count = 0;
bool consumed_ = false;
public:
event_queue_peeker_t(input_event_queue_t &event_queue)
: event_queue_(event_queue) {
}
char_event_t next(bool timed = false) {
assert(count < N && "Insufficient backing array size!");
auto event = timed ? event_queue_.readch_timed() : event_queue_.readch();
peeked_[count++] = event;
return event;
}
size_t len() {
return count;
}
void consume() {
consumed_ = true;
}
void restart() {
if (count > 0) {
event_queue_.insert_front(peeked_.cbegin(), peeked_.cbegin() + count);
count = 0;
}
}
~event_queue_peeker_t() {
if (!consumed_) {
restart();
}
}
};
void inputter_t::mapping_execute_matching_or_generic(const command_handler_t &command_handler) {
if (auto mapping = find_mapping()) {
mapping_execute(*mapping, command_handler);

View file

@ -107,6 +107,9 @@ enum class char_event_type_t : uint8_t {
/// An event was handled internally, or an interrupt was received. Check to see if the reader
/// loop should exit.
check_exit,
/// There is no event. This should never happen, or is an assertion failure.
none,
};
/// Hackish: the input style, which describes how char events (only) are applied to the command
@ -154,11 +157,21 @@ class char_event_t {
return v_.c;
}
maybe_t<wchar_t> maybe_char() const {
if (type == char_event_type_t::charc) {
return v_.c;
} else {
return none();
}
}
readline_cmd_t get_readline() const {
assert(type == char_event_type_t::readline && "Not a readline type");
return v_.rl;
}
explicit char_event_t() : type(char_event_type_t::none) { }
/* implicit */ char_event_t(wchar_t c) : type(char_event_type_t::charc) { v_.c = c; }
/* implicit */ char_event_t(readline_cmd_t rl, wcstring seq = {})