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Keep track of key bounds in FlatMap #27

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Keep track of key bounds in FlatMap #27

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73 changes: 62 additions & 11 deletions src/flat_map/include/sourcemeta/noa/flat_map.h
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Original file line number Diff line number Diff line change
@@ -1,10 +1,12 @@
#ifndef SOURCEMETA_NOA_FLAT_MAP_H_
#define SOURCEMETA_NOA_FLAT_MAP_H_

#include <algorithm> // std::swap
#include <cassert> // assert
#include <algorithm> // std::swap
#include <algorithm> // std::min, std::max, std::min_element, std::max_element
#include <cassert> // assert
#include <initializer_list> // std::initializer_list
#include <iterator> // std::advance
#include <limits> // std::numeric_limits
#include <utility> // std::pair, std::move
#include <vector> // std::vector

Expand Down Expand Up @@ -56,6 +58,9 @@ template <typename Key, typename Value, typename Hash> class FlatMap {
}

auto assign(key_type &&key, mapped_type &&value) -> hash_type {
const auto key_size{key.size()};
this->key_lower_size = std::min(this->key_lower_size, key_size);
this->key_upper_size = std::max(this->key_upper_size, key_size);
const auto key_hash{this->hash(key)};

if (this->hasher.is_perfect(key_hash)) {
Expand All @@ -79,6 +84,9 @@ template <typename Key, typename Value, typename Hash> class FlatMap {
}

auto assign(const key_type &key, const mapped_type &value) -> hash_type {
const auto key_size{key.size()};
this->key_lower_size = std::min(this->key_lower_size, key_size);
this->key_upper_size = std::max(this->key_upper_size, key_size);
const auto key_hash{this->hash(key)};

if (this->hasher.is_perfect(key_hash)) {
Expand All @@ -105,6 +113,10 @@ template <typename Key, typename Value, typename Hash> class FlatMap {
inline auto find(const key_type &key, const hash_type key_hash) const
-> const_iterator {
assert(this->hash(key) == key_hash);
const auto key_size{key.size()};
if (key_size < this->key_lower_size || key_size > this->key_upper_size) {
return this->cend();
}

// Move the perfect hash condition out of the loop for extra performance
if (this->hasher.is_perfect(key_hash)) {
Expand All @@ -129,9 +141,14 @@ template <typename Key, typename Value, typename Hash> class FlatMap {
return this->cend();
}

inline auto try_at(const key_type &key, const hash_type key_hash) const
inline auto try_at(const key_type &key,
const hash_type key_hash) const noexcept
-> const mapped_type * {
assert(this->hash(key) == key_hash);
const auto key_size{key.size()};
if (key_size < this->key_lower_size || key_size > this->key_upper_size) {
return nullptr;
}

// Move the perfect hash condition out of the loop for extra performance
if (this->hasher.is_perfect(key_hash)) {
Expand All @@ -155,6 +172,10 @@ template <typename Key, typename Value, typename Hash> class FlatMap {
// As a performance optimisation if the hash is known
auto contains(const key_type &key, const hash_type key_hash) const -> bool {
assert(this->hash(key) == key_hash);
const auto key_size{key.size()};
if (key_size < this->key_lower_size || key_size > this->key_upper_size) {
return false;
}

// Move the perfect hash condition out of the loop for extra performance
if (this->hasher.is_perfect(key_hash)) {
Expand All @@ -176,7 +197,7 @@ template <typename Key, typename Value, typename Hash> class FlatMap {

// As a performance optimisation if the hash is known

inline auto at(const key_type &key, const hash_type key_hash) const
inline auto at(const key_type &key, const hash_type key_hash) const noexcept
-> const mapped_type & {
assert(this->hash(key) == key_hash);

Expand All @@ -203,7 +224,7 @@ template <typename Key, typename Value, typename Hash> class FlatMap {
#endif
}

inline auto at(const key_type &key, const hash_type key_hash)
inline auto at(const key_type &key, const hash_type key_hash) noexcept
-> mapped_type & {
assert(this->hash(key) == key_hash);

Expand Down Expand Up @@ -235,26 +256,43 @@ template <typename Key, typename Value, typename Hash> class FlatMap {
}

auto erase(const key_type &key, const hash_type key_hash) -> size_type {
const auto current_size{this->size()};
auto current_size{this->size()};

if (this->hasher.is_perfect(key_hash)) {
for (auto &entry : this->data) {
if (entry.hash == key_hash) {
std::swap(entry, this->data.back());
this->data.pop_back();
return current_size - 1;
current_size -= 1;
break;
}
}
} else {
for (auto &entry : this->data) {
if (entry.hash == key_hash && entry.first == key) {
std::swap(entry, this->data.back());
this->data.pop_back();
return current_size - 1;
current_size -= 1;
break;
}
}
}

if (!this->data.empty()) {
this->key_lower_size =
std::min_element(this->data.cbegin(), this->data.cend(),
[](const auto &left, const auto &right) {
return left.first.size() < right.first.size();
})
->first.size();
this->key_upper_size =
std::max_element(this->data.cbegin(), this->data.cend(),
[](const auto &left, const auto &right) {
return left.first.size() < right.first.size();
})
->first.size();
}

return current_size;
}

Expand All @@ -264,14 +302,25 @@ template <typename Key, typename Value, typename Hash> class FlatMap {

inline auto size() const noexcept -> size_type { return this->data.size(); }

inline auto empty() const noexcept -> bool { return this->data.empty(); }
inline auto empty() const noexcept -> bool {
assert(!this->data.empty() ||
this->key_lower_size == std::numeric_limits<std::size_t>::max());
assert(!this->data.empty() || this->key_upper_size == 0);
return this->data.empty();
}

inline auto clear() noexcept -> void { this->data.clear(); }
inline auto clear() noexcept -> void {
this->key_lower_size = std::numeric_limits<std::size_t>::max();
this->key_upper_size = 0;
this->data.clear();
}

auto operator!=(const FlatMap &other) const -> bool = default;

auto operator==(const FlatMap &other) const -> bool {
if (this->size() != other.size()) {
if (this->size() != other.size() ||
this->key_lower_size != other.key_lower_size ||
this->key_upper_size != other.key_upper_size) {
return false;
}

Expand All @@ -290,6 +339,8 @@ template <typename Key, typename Value, typename Hash> class FlatMap {
private:
underlying_type data;
Hash hasher;
std::size_t key_lower_size{std::numeric_limits<std::size_t>::max()};
std::size_t key_upper_size{0};
};

} // namespace sourcemeta::noa
Expand Down
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