b6bc9d72f6
This is step 4 of https://discourse.llvm.org/t/rfc-customizable-namespace-to-allow-testing-the-libc-when-the-system-libc-is-also-llvms-libc/73079
63 lines
2.0 KiB
C++
63 lines
2.0 KiB
C++
//===-- A data structure for a fixed capacity data store --------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIBC_SRC___SUPPORT_FIXEDVECTOR_H
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#define LLVM_LIBC_SRC___SUPPORT_FIXEDVECTOR_H
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#include "src/__support/CPP/array.h"
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namespace LIBC_NAMESPACE {
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// A fixed size data store backed by an underlying cpp::array data structure. It
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// supports vector like API but is not resizable like a vector.
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template <typename T, size_t CAPACITY> class FixedVector {
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cpp::array<T, CAPACITY> store;
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size_t item_count = 0;
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public:
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constexpr FixedVector() = default;
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bool push_back(const T &obj) {
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if (item_count == CAPACITY)
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return false;
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store[item_count] = obj;
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++item_count;
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return true;
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}
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const T &back() const { return store[item_count - 1]; }
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T &back() { return store[item_count - 1]; }
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bool pop_back() {
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if (item_count == 0)
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return false;
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--item_count;
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return true;
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}
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bool empty() const { return item_count == 0; }
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// Empties the store for all practical purposes.
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void reset() { item_count = 0; }
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// This static method does not free up the resources held by |store|,
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// say by calling `free` or something similar. It just does the equivalent
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// of the `reset` method. Considering that FixedVector is of fixed storage,
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// a `destroy` method like this should not be required. However, FixedVector
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// is used in a few places as an alternate for data structures which use
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// dynamically allocated storate. So, the `destroy` method like this
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// matches the `destroy` API of those other data structures so that users
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// can easily swap one data structure for the other.
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static void destroy(FixedVector<T, CAPACITY> *store) { store->reset(); }
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};
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} // namespace LIBC_NAMESPACE
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#endif // LLVM_LIBC_SRC___SUPPORT_FIXEDVECTOR_H
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