mirror of
https://github.com/carbon-language/carbon-lang.git
synced 2026-09-25 12:50:12 +01:00
Jon MeowandGeoff Romer
9007bfcb88
`// NOLINT` is added on type aliases in stack.h and dictionary.h to allow lower_snake_case naming -- this didn't feel like a check worth disabling in spite of false positives. Co-authored-by: Geoff Romer <gromer@google.com>
105 lines
3.2 KiB
C++
105 lines
3.2 KiB
C++
// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
|
|
// Exceptions. See /LICENSE for license information.
|
|
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
|
|
|
|
#ifndef EXECUTABLE_SEMANTICS_INTERPRETER_DICTIONARY_H_
|
|
#define EXECUTABLE_SEMANTICS_INTERPRETER_DICTIONARY_H_
|
|
|
|
#include <iterator>
|
|
#include <optional>
|
|
|
|
#include "executable_semantics/common/arena.h"
|
|
|
|
namespace Carbon {
|
|
|
|
// A persistent dictionary with a simple implementation.
|
|
// Copying the dictionary is O(1) time.
|
|
template <class K, class V>
|
|
class Dictionary {
|
|
public:
|
|
struct Node {
|
|
using ValueType = std::pair<K, V>;
|
|
|
|
Node(ValueType e, std::optional<Nonnull<Node*>> n) : curr(e), next(n) {}
|
|
|
|
const ValueType curr;
|
|
const std::optional<Nonnull<Node*>> next;
|
|
|
|
// Node cells are part of a "persistent data structure" and are thus
|
|
// immutable.
|
|
auto operator=(const Node&) -> Node& = delete;
|
|
auto operator=(Node&&) -> Node& = delete;
|
|
};
|
|
|
|
// A forward iterator over elements of a `Node` list.
|
|
struct Iterator {
|
|
// NOLINTNEXTLINE(readability-identifier-naming)
|
|
using value_type = typename Node::ValueType;
|
|
// NOLINTNEXTLINE(readability-identifier-naming)
|
|
using difference_type = std::ptrdiff_t;
|
|
// NOLINTNEXTLINE(readability-identifier-naming)
|
|
using pointer = const value_type*;
|
|
// NOLINTNEXTLINE(readability-identifier-naming)
|
|
using reference = const value_type&;
|
|
// NOLINTNEXTLINE(readability-identifier-naming)
|
|
using iterator_category = std::forward_iterator_tag;
|
|
|
|
explicit Iterator(std::optional<Nonnull<Node*>> x) : p(x) {}
|
|
Iterator(const Iterator& iter) : p(iter.p) {}
|
|
auto operator++() -> Iterator& {
|
|
p = (*p)->next;
|
|
return *this;
|
|
}
|
|
auto operator++(int) -> Iterator {
|
|
Iterator tmp(*this);
|
|
operator++();
|
|
return tmp;
|
|
}
|
|
auto operator==(const Iterator& rhs) const -> bool { return p == rhs.p; }
|
|
auto operator!=(const Iterator& rhs) const -> bool { return p != rhs.p; }
|
|
auto operator*() -> const value_type& { return (*p)->curr; }
|
|
auto operator->() -> const value_type* { return &(*p)->curr; }
|
|
|
|
private:
|
|
std::optional<Nonnull<Node*>> p;
|
|
};
|
|
|
|
// Create an empty dictionary.
|
|
explicit Dictionary(Nonnull<Arena*> arena) : arena(arena) {}
|
|
|
|
// Return the value associated with the given key.
|
|
// Time complexity: O(n) where n is the number of times
|
|
// any value has been set across all keys.
|
|
auto Get(const K& key) -> std::optional<V> {
|
|
for (auto kv : *this) {
|
|
if (kv.first == key) {
|
|
return kv.second;
|
|
}
|
|
}
|
|
return std::nullopt;
|
|
}
|
|
|
|
// Associate the value v with key k in the dictionary.
|
|
// Time complexity: O(1).
|
|
auto Set(const K& k, const V& v) -> void {
|
|
head = arena->New<Node>(std::make_pair(k, v), head);
|
|
}
|
|
|
|
auto IsEmpty() -> bool { return !head; }
|
|
|
|
// The position of the first element of the dictionary
|
|
// or `end()` if the dictionary is empty.
|
|
auto begin() const -> Iterator { return Iterator(head); }
|
|
|
|
// The position one past that of the last element.
|
|
auto end() const -> Iterator { return Iterator(std::nullopt); }
|
|
|
|
private:
|
|
std::optional<Nonnull<Node*>> head;
|
|
Nonnull<Arena*> arena;
|
|
};
|
|
|
|
} // namespace Carbon
|
|
|
|
#endif // EXECUTABLE_SEMANTICS_INTERPRETER_DICTIONARY_H_
|