mirror of
https://github.com/carbon-language/carbon-lang.git
synced 2026-09-24 19:40:10 +01:00
Jon Meow
20728dbd3a
This modifies scripts/check_header_guards.py to add the CARBON_ prefix; everything else is pre-commit.
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
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// Exceptions. See /LICENSE for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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#ifndef CARBON_EXPLORER_INTERPRETER_DICTIONARY_H_
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#define CARBON_EXPLORER_INTERPRETER_DICTIONARY_H_
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#include <iterator>
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#include <optional>
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#include "explorer/common/arena.h"
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namespace Carbon {
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// A persistent dictionary with a simple implementation.
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// Copying the dictionary is O(1) time.
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template <class K, class V>
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class Dictionary {
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public:
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struct Node {
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using ValueType = std::pair<K, V>;
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Node(ValueType e, std::optional<Nonnull<Node*>> n) : curr(e), next(n) {}
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const ValueType curr;
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const std::optional<Nonnull<Node*>> next;
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// Node cells are part of a "persistent data structure" and are thus
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// immutable.
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auto operator=(const Node&) -> Node& = delete;
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auto operator=(Node&&) -> Node& = delete;
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};
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// A forward iterator over elements of a `Node` list.
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struct Iterator {
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// NOLINTNEXTLINE(readability-identifier-naming)
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using value_type = typename Node::ValueType;
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// NOLINTNEXTLINE(readability-identifier-naming)
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using difference_type = std::ptrdiff_t;
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// NOLINTNEXTLINE(readability-identifier-naming)
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using pointer = const value_type*;
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// NOLINTNEXTLINE(readability-identifier-naming)
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using reference = const value_type&;
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// NOLINTNEXTLINE(readability-identifier-naming)
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using iterator_category = std::forward_iterator_tag;
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explicit Iterator(std::optional<Nonnull<Node*>> x) : p_(x) {}
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Iterator(const Iterator& iter) : p_(iter.p_) {}
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auto operator++() -> Iterator& {
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p_ = (*p_)->next;
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return *this;
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}
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auto operator++(int) -> Iterator {
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Iterator tmp(*this);
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operator++();
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return tmp;
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}
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auto operator==(const Iterator& rhs) const -> bool { return p_ == rhs.p_; }
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auto operator!=(const Iterator& rhs) const -> bool { return p_ != rhs.p_; }
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auto operator*() -> const value_type& { return (*p_)->curr; }
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auto operator->() -> const value_type* { return &(*p_)->curr; }
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private:
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std::optional<Nonnull<Node*>> p_;
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};
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// Create an empty dictionary.
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explicit Dictionary(Nonnull<Arena*> arena) : arena_(arena) {}
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// Return the value associated with the given key.
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// Time complexity: O(n) where n is the number of times
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// any value has been set across all keys.
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auto Get(const K& key) -> std::optional<V> {
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for (auto kv : *this) {
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if (kv.first == key) {
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return kv.second;
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}
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}
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return std::nullopt;
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}
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// Associate the value v with key k in the dictionary.
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// Time complexity: O(1).
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auto Set(const K& k, const V& v) -> void {
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head_ = arena_->New<Node>(std::make_pair(k, v), head_);
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}
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auto IsEmpty() -> bool { return !head_; }
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// The position of the first element of the dictionary
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// or `end()` if the dictionary is empty.
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auto begin() const -> Iterator { return Iterator(head_); }
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// The position one past that of the last element.
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auto end() const -> Iterator { return Iterator(std::nullopt); }
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private:
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std::optional<Nonnull<Node*>> head_;
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Nonnull<Arena*> arena_;
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};
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} // namespace Carbon
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#endif // CARBON_EXPLORER_INTERPRETER_DICTIONARY_H_
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