Initial drop of cppdap

include/dap/any.h

@@ -0,0 +1,182 @@
+// Copyright 2019 Google LLC
+//
+// 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
+//
+//     https://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.
+
+#ifndef dap_any_h
+#define dap_any_h
+
+#include "typeinfo.h"
+
+#include <assert.h>
+
+namespace dap {
+
+template <typename T>
+struct TypeOf;
+
+// any provides a type-safe container for values of any of dap type (boolean,
+// integer, number, array, variant, any, null, dap-structs).
+class any {
+ public:
+  // constructors
+  inline any() = default;
+  inline any(const any& other) noexcept;
+  inline any(any&& other) noexcept;
+
+  template <typename T>
+  inline any(const T& val);
+
+  // destructors
+  inline ~any();
+
+  // replaces the contained value with a null.
+  inline void reset();
+
+  // assignment
+  inline any& operator=(const any& rhs);
+  inline any& operator=(any&& rhs) noexcept;
+  template <typename T>
+  inline any& operator=(const T& val);
+
+  // get() returns the contained value of the type T.
+  // If the any does not contain a value of type T, then get() will assert.
+  template <typename T>
+  inline T& get() const;
+
+  // is() returns true iff the contained value is of type T.
+  template <typename T>
+  inline bool is() const;
+
+ private:
+  static inline void* alignUp(void* val, size_t alignment);
+  inline void alloc(size_t size, size_t align);
+  inline void free();
+  inline bool isInBuffer(void* ptr) const;
+
+  void* value = nullptr;
+  const TypeInfo* type = nullptr;
+  void* heap = nullptr;  // heap allocation
+  uint8_t buffer[32];    // or internal allocation
+};
+
+inline any::~any() {
+  reset();
+}
+
+template <typename T>
+inline any::any(const T& val) {
+  *this = val;
+}
+
+any::any(const any& other) noexcept : type(other.type) {
+  if (other.value != nullptr) {
+    alloc(type->size(), type->alignment());
+    type->copyConstruct(value, other.value);
+  }
+}
+
+any::any(any&& other) noexcept : value(other.value), type(other.type) {
+  other.value = nullptr;
+  other.type = nullptr;
+}
+
+void any::reset() {
+  if (value != nullptr) {
+    type->destruct(value);
+    free();
+  }
+  value = nullptr;
+  type = nullptr;
+}
+
+any& any::operator=(const any& rhs) {
+  reset();
+  type = rhs.type;
+  if (rhs.value != nullptr) {
+    alloc(type->size(), type->alignment());
+    type->copyConstruct(value, rhs.value);
+  }
+  return *this;
+}
+
+any& any::operator=(any&& rhs) noexcept {
+  value = rhs.value;
+  type = rhs.type;
+  rhs.value = nullptr;
+  rhs.type = nullptr;
+  return *this;
+}
+
+template <typename T>
+any& any::operator=(const T& val) {
+  if (!is<T>()) {
+    reset();
+    type = TypeOf<T>::type();
+    alloc(type->size(), type->alignment());
+    type->copyConstruct(value, &val);
+  } else {
+    *reinterpret_cast<T*>(value) = val;
+  }
+  return *this;
+}
+
+template <typename T>
+T& any::get() const {
+  assert(is<T>());
+  return *reinterpret_cast<T*>(value);
+}
+
+template <typename T>
+bool any::is() const {
+  return type == TypeOf<T>::type();
+}
+
+template <>
+inline bool any::is<std::nullptr_t>() const {
+  return value == nullptr;
+}
+
+void* any::alignUp(void* val, size_t alignment) {
+  auto ptr = reinterpret_cast<uintptr_t>(val);
+  return reinterpret_cast<void*>(alignment *
+                                 ((ptr + alignment - 1) / alignment));
+}
+
+void any::alloc(size_t size, size_t align) {
+  assert(value == nullptr);
+  value = alignUp(buffer, align);
+  if (isInBuffer(reinterpret_cast<uint8_t*>(value) + size - 1)) {
+    return;
+  }
+  heap = new uint8_t[size + align];
+  value = alignUp(heap, align);
+}
+
+void any::free() {
+  assert(value != nullptr);
+  if (heap != nullptr) {
+    delete[] reinterpret_cast<uint8_t*>(heap);
+    heap = nullptr;
+  }
+  value = nullptr;
+}
+
+bool any::isInBuffer(void* ptr) const {
+  auto addr = reinterpret_cast<uintptr_t>(ptr);
+  return addr >= reinterpret_cast<uintptr_t>(buffer) &&
+         addr < reinterpret_cast<uintptr_t>(buffer + sizeof(buffer));
+}
+
+}  // namespace dap
+
+#endif  // dap_any_h