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https://github.com/carbon-language/carbon-lang.git
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Jon Meow
47325be112
This also eliminates the ctad wrapper for Stack: I think the leaning is to remove it. It felt worth keeping the constructor because constructing with a single element is a common use-case. Adds a single-argument constructor for Scope because the `std::list<std::string>()` is common, and eliding it is consistent with what we've done for things like tuples. I was considering a vector constructor due to the double-Push on line 1139, but thought the Push() semantics may mean that it's better not to provide.
75 lines
2.0 KiB
C++
75 lines
2.0 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 EXECUTABLE_SEMANTICS_INTERPRETER_STACK_H_
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#define EXECUTABLE_SEMANTICS_INTERPRETER_STACK_H_
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#include <cstddef>
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#include <iterator>
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#include <vector>
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#include "common/check.h"
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namespace Carbon {
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// A stack data structure.
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template <class T>
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struct Stack {
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using const_iterator = typename std::vector<T>::const_reverse_iterator;
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// Creates an empty instance.
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Stack() = default;
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// Creates an instance containing just `x`.
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explicit Stack(T x) : Stack() { Push(std::move(x)); }
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// Pushes `x` onto the top of the stack.
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void Push(T x) { elements.push_back(std::move(x)); }
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// Removes and returns the top element of the stack.
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//
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// - Requires: !this->IsEmpty()
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auto Pop() -> T {
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CHECK(!IsEmpty()) << "Can't pop from empty stack.";
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auto r = std::move(elements.back());
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elements.pop_back();
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return r;
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}
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// Removes the top `n` elements of the stack.
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//
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// - Requires: n >= 0 && n <= Count()
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void Pop(int n) {
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CHECK(n >= 0) << "Negative pop count disallowed.";
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CHECK(static_cast<size_t>(n) <= elements.size())
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<< "Can only pop as many elements as stack has.";
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elements.erase(elements.end() - n, elements.end());
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}
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// Returns the top element of the stack.
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//
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// - Requires: !this->IsEmpty()
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auto Top() const -> T {
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CHECK(!IsEmpty()) << "Empty stack has no Top().";
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return elements.back();
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}
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// Returns `true` iff `Count() > 0`.
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auto IsEmpty() const -> bool { return elements.empty(); }
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// Returns the number of elements in `*this`.
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auto Count() const -> int { return elements.size(); }
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// Iterates over the Stack from top to bottom.
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const_iterator begin() const { return elements.crbegin(); }
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const_iterator end() const { return elements.crend(); }
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private:
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std::vector<T> elements;
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};
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} // namespace Carbon
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#endif // EXECUTABLE_SEMANTICS_INTERPRETER_CONS_LIST_H_
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