C++ bindings

mojo/public/bindings/bindings.h

+// Copyright 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef MOJO_PUBLIC_BINDINGS_BINDINGS_H_
+#define MOJO_PUBLIC_BINDINGS_BINDINGS_H_
+
+#include <assert.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "mojo/public/system/core.h"
+
+namespace mojo {
+
+//-----------------------------------------------------------------------------
+
+struct Message {
+  uint32_t name;
+  uint8_t* data_start;
+  uint8_t* data_end;
+  Handle* handles_start;
+  Handle* handles_end;
+};
+
+class MessageSender {
+ public:
+  virtual void Send(const Message& message) = 0;
+};
+
+//-----------------------------------------------------------------------------
+
+struct MessageHeader {
+  uint32_t num_bytes;
+  uint32_t name;
+};
+
+struct StructHeader {
+  uint32_t num_bytes;
+  uint32_t num_fields;
+};
+
+struct ArrayHeader {
+  uint32_t num_bytes;
+  uint32_t num_elements;
+};
+
+//-----------------------------------------------------------------------------
+
+template <typename T> class Array;
+
+namespace internal {
+template <typename T> class Traits {};
+}
+
+template <typename T>
+union StructPointer {
+  uint64_t offset;
+  T* ptr;
+};
+
+template <typename T>
+union ArrayPointer {
+  uint64_t offset;
+  Array<T>* ptr;
+};
+
+template <typename T>
+struct TypeTraits {
+  typedef T StorageType;
+
+  static T& ToRef(StorageType& e) { return e; }
+  static T const& ToConstRef(const StorageType& e) { return e; }
+};
+
+template <typename P>
+struct TypeTraits<P*> {
+  typedef StructPointer<P> StorageType;
+
+  static P*& ToRef(StorageType& e) { return e.ptr; }
+  static P* const& ToConstRef(const StorageType& e) { return e.ptr; }
+};
+
+template <typename T>
+class Array {
+ public:
+  explicit Array(size_t num_elements) {
+    // TODO: bools should get packed to a single bit?
+    header_.num_bytes =
+        sizeof(*this) +
+        sizeof(typename TypeTraits<T>::StorageType) * (num_elements - 1);
+    header_.num_elements = num_elements;
+  }
+
+  size_t size() const { return header_.num_elements; }
+
+  T& at(size_t offset) {
+    return TypeTraits<T>::ToRef(elements_[offset]);
+  }
+
+  const T& at(size_t offset) const {
+    return TypeTraits<T>::ToConstRef(elements_[offset]);
+  }
+
+  T& operator[](size_t offset) {
+    return TypeTraits<T>::ToRef(elements_[offset]);
+  }
+
+  const T& operator[](size_t offset) const {
+    return TypeTraits<T>::ToConstRef(elements_[offset]);
+  }
+
+ private:
+  friend class internal::Traits<Array<T> >;
+
+  ArrayHeader header_;
+  typename TypeTraits<T>::StorageType elements_[1];  // Extra elements follow.
+};
+
+//-----------------------------------------------------------------------------
+
+// The following is a cheezy arena allocator.
+class MessageBuffer {
+ public:
+  MessageBuffer() : ptr_(NULL), size_(0) {
+  }
+  ~MessageBuffer() { free(ptr_); }
+
+  const uint8_t* data() const { return ptr_; }
+  uint8_t* data() { return ptr_; }
+
+  size_t size() const { return size_; }
+
+  uint8_t* AllocBytes(size_t size) {
+    return Grow(size);
+  }
+
+  template <typename T>
+  T* Alloc() {
+    size_t size = sizeof(T);
+    return new (Grow(size)) T();
+  }
+
+  template <typename T>
+  Array<T>* AllocArray(size_t count) {
+    // (count - 1) because Array<T> has reserved space for the first element.
+    size_t size = sizeof(Array<T>) + sizeof(T) * (count - 1);
+    return new (Grow(size)) Array<T>(count);
+  }
+
+ private:
+  uint8_t* Grow(size_t delta) {
+    // TODO: Align allocations
+    size_t old_size = size_;
+    size_t new_size = old_size + delta;
+    ptr_ = static_cast<uint8_t*>(realloc(ptr_, old_size + delta));
+    size_ = new_size;
+    uint8_t* result = ptr_ + old_size;
+    memset(result, 0, delta);
+    return result;
+  }
+
+  uint8_t* ptr_;
+  size_t size_;
+
+  // NOT IMPLEMENTED
+  MessageBuffer(const MessageBuffer&);
+  void operator=(const MessageBuffer&);
+};
+
+}  // namespace mojo
+
+#endif  // MOJO_PUBLIC_BINDINGS_BINDINGS_H_