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/*
* Copyright 2022 WebAssembly Community Group participants
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
// A helper type for potentially sparse N*N matrix container.
#pragma once
#include <assert.h>
#include <stdint.h>
#include <unordered_map>
#include <vector>
template<typename Ty> class sparse_square_matrix {
std::vector<Ty> denseStorage;
std::unordered_map<uint64_t, Ty> sparseStorage;
uint32_t N;
public:
sparse_square_matrix() : N(0) {}
explicit sparse_square_matrix(int N) : N(N) {
if (N < DenseLimit) {
denseStorage.resize(N * N);
}
}
static const size_t DenseLimit = 8192;
uint32_t width() const { return N; }
bool usingDenseStorage() const { return !denseStorage.empty(); }
void set(uint32_t i, uint32_t j, const Ty& value) {
assert(i < N);
assert(j < N);
if (usingDenseStorage()) {
denseStorage[i * N + j] = value;
} else {
sparseStorage[i * N + j] = value;
}
}
const Ty get(uint32_t i, uint32_t j) const {
assert(i < N);
assert(j < N);
if (usingDenseStorage()) {
return denseStorage[i * N + j];
}
auto iter = sparseStorage.find(i * N + j);
return iter == sparseStorage.end() ? Ty() : iter->second;
}
// Resizes the matrix to a new n*n size, and clears all entries
// to the default-initialized value.
void recreate(uint32_t n) {
N = n;
denseStorage.clear();
sparseStorage.clear();
if (N < DenseLimit) {
denseStorage.resize(N * N);
}
}
};
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