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