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Change-Id: I4bf1707bd3dfeadf2c17b0a7daff372b1925ebbd

runtime/utilities/stackvec.h

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+/*
+ * Copyright (c) 2017, Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+ * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#pragma once
+
+#include <cinttypes>
+#include <cstddef>
+#include <vector>
+
+template <typename DataType, uint32_t OnStackCapacity>
+class StackVec {
+  public:
+    static const uint32_t onStackCaps = OnStackCapacity;
+
+    StackVec()
+        : dynamicMem(nullptr) {
+    }
+
+    template <typename ItType>
+    StackVec(ItType beginIt, ItType endIt)
+        : dynamicMem(nullptr) {
+        size_t count = (endIt - beginIt);
+        if (count > OnStackCapacity) {
+            dynamicMem = new std::vector<DataType>(beginIt, endIt);
+            return;
+        }
+
+        while (beginIt != endIt) {
+            push_back(*beginIt);
+            ++beginIt;
+        }
+        onStackSize = static_cast<uint32_t>(count);
+    }
+
+    StackVec(const StackVec &rhs)
+        : dynamicMem(nullptr) {
+        if (onStackCaps < rhs.size()) {
+            dynamicMem = new std::vector<DataType>(rhs.begin(), rhs.end());
+            return;
+        }
+
+        for (const auto &v : rhs) {
+            push_back(v);
+        }
+    }
+    StackVec &operator=(const StackVec &rhs) {
+        clear();
+
+        if (this->dynamicMem != nullptr) {
+            this->dynamicMem->insert(dynamicMem->end(), rhs.begin(), rhs.end());
+            return *this;
+        }
+
+        if (onStackCaps < rhs.size()) {
+            this->dynamicMem = new std::vector<DataType>(rhs.begin(), rhs.end());
+            return *this;
+        }
+
+        for (const auto &v : rhs) {
+            push_back(v);
+        }
+
+        return *this;
+    }
+    StackVec(StackVec &&rhs)
+        : dynamicMem(nullptr) {
+        if (rhs.dynamicMem != nullptr) {
+            std::swap(this->dynamicMem, rhs.dynamicMem);
+            return;
+        }
+
+        for (const auto &v : rhs) {
+            push_back(v);
+        }
+    }
+    StackVec &operator=(StackVec &&rhs) {
+        clear();
+
+        if (rhs.dynamicMem != nullptr) {
+            std::swap(this->dynamicMem, rhs.dynamicMem);
+            return *this;
+        }
+
+        if (this->dynamicMem != nullptr) {
+            this->dynamicMem->insert(this->dynamicMem->end(), rhs.begin(), rhs.end());
+            return *this;
+        }
+
+        for (const auto &v : rhs) {
+            push_back(v);
+        }
+
+        return *this;
+    }
+
+    ~StackVec() {
+        if (dynamicMem != nullptr) {
+            delete dynamicMem;
+            return;
+        }
+        clear();
+    }
+
+    size_t size() const {
+        if (dynamicMem) {
+            return dynamicMem->size();
+        }
+        return onStackSize;
+    }
+
+    size_t capacity() const {
+        if (dynamicMem) {
+            return dynamicMem->capacity();
+        }
+        return OnStackCapacity;
+    }
+
+    void reserve(size_t newCapacity) {
+        if (newCapacity > onStackCaps) {
+            ensureDynamicMem();
+            dynamicMem->reserve(newCapacity);
+        }
+    }
+
+    void clear() {
+        if (dynamicMem) {
+            dynamicMem->clear();
+            return;
+        }
+        clearStackObjets();
+    }
+
+    void push_back(const DataType &v) { // NOLINT
+        if (onStackSize == onStackCaps) {
+            ensureDynamicMem();
+        }
+
+        if (dynamicMem) {
+            dynamicMem->push_back(v);
+            return;
+        }
+
+        new (onStackMem + onStackSize) DataType(v);
+        ++onStackSize;
+    }
+
+    DataType &operator[](std::size_t idx) {
+        if (dynamicMem) {
+            return (*dynamicMem)[idx];
+        }
+        return *(onStackMem + idx);
+    }
+
+    const DataType &operator[](std::size_t idx) const {
+        if (dynamicMem) {
+            return (*dynamicMem)[idx];
+        }
+        return *(onStackMem + idx);
+    }
+
+    DataType *begin() {
+        if (dynamicMem) {
+            return dynamicMem->data();
+        }
+
+        return onStackMem;
+    }
+
+    const DataType *begin() const {
+        if (dynamicMem) {
+            return dynamicMem->data();
+        }
+
+        return onStackMem;
+    }
+
+    DataType *end() {
+        if (dynamicMem) {
+            return dynamicMem->data() + dynamicMem->size();
+        }
+
+        return onStackMem + onStackSize;
+    }
+
+    const DataType *end() const {
+        if (dynamicMem) {
+            return dynamicMem->data() + dynamicMem->size();
+        }
+
+        return onStackMem + onStackSize;
+    }
+
+    void resize(size_t newCapacity) {
+        if (newCapacity > onStackCaps) {
+            ensureDynamicMem();
+            dynamicMem->resize(newCapacity);
+        }
+    }
+
+  private:
+    void ensureDynamicMem() {
+        if (dynamicMem == nullptr) {
+            dynamicMem = new std::vector<DataType>();
+            if (onStackSize > 0) {
+                dynamicMem->reserve(onStackSize);
+                for (auto it = onStackMem, end = onStackMem + onStackSize; it != end; ++it) {
+                    dynamicMem->push_back(std::move(*it));
+                }
+                clearStackObjets();
+            }
+        }
+    }
+
+    void clearStackObjets() {
+        for (auto it = onStackMem, end = onStackMem + onStackSize; it != end; ++it) {
+            it->~DataType();
+        }
+        onStackSize = 0;
+    }
+
+    alignas(alignof(DataType)) char onStackMemRawBytes[sizeof(DataType[onStackCaps])];
+    std::vector<DataType> *dynamicMem;
+    DataType *const onStackMem = reinterpret_cast<DataType *const>(onStackMemRawBytes);
+    uint32_t onStackSize = 0;
+};