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 <new>
+#include <vector>
+
+#include "mojo/public/system/core.h"
+
+namespace mojo {
+
+template <typename T> class Array;
+class String;
+
+namespace internal {
+
+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>
+union StructPointer {
+  uint64_t offset;
+  T* ptr;
+};
+
+template <typename T>
+union ArrayPointer {
+  uint64_t offset;
+  Array<T>* ptr;
+};
+
+union StringPointer {
+  uint64_t offset;
+  String* ptr;
+};
+
+template <typename T>
+struct ArrayTraits {
+  typedef T StorageType;
+
+  static T& ToRef(StorageType& e) { return e; }
+  static T const& ToConstRef(const StorageType& e) { return e; }
+};
+
+template <typename P>
+struct ArrayTraits<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 ObjectTraits {};
+
+}  // namespace internal
+
+//-----------------------------------------------------------------------------
+
+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 internal::ArrayTraits<T>::StorageType) *
+            (num_elements - 1);
+    header_.num_elements = num_elements;
+  }
+
+  size_t size() const { return header_.num_elements; }
+
+  T* data() { return elements_; }
+  const T* data() const { return elements_; }
+
+  T& at(size_t offset) {
+    return internal::ArrayTraits<T>::ToRef(elements_[offset]);
+  }
+
+  const T& at(size_t offset) const {
+    return internal::ArrayTraits<T>::ToConstRef(elements_[offset]);
+  }
+
+  T& operator[](size_t offset) {
+    return at(offset);
+  }
+
+  const T& operator[](size_t offset) const {
+    return at(offset);
+  }
+
+ private:
+  friend class internal::ObjectTraits<Array<T> >;
+  friend class internal::ObjectTraits<String>;
+
+  internal::ArrayHeader header_;
+
+  // Extra elements follow.
+  typename internal::ArrayTraits<T>::StorageType elements_[1];
+};
+
+//-----------------------------------------------------------------------------
+
+// UTF-8 encoded
+class String : public Array<char> {
+ public:
+  explicit String(size_t num_chars)
+      : Array<char>(num_chars) {
+  }
+
+  char& operator[](size_t offset) {
+    return at(offset);
+  }
+
+  const char& operator[](size_t offset) const {
+    return at(offset);
+  }
+};
+
+//-----------------------------------------------------------------------------
+
+struct Message {
+  uint32_t name;
+  uint8_t* data_start;
+  uint8_t* data_end;
+  //XXX MessageBuffer data;
+  std::vector<Handle> handles;
+};
+
+class MessageSender {
+ public:
+  virtual void Send(const Message& message) = 0;
+};
+
+//-----------------------------------------------------------------------------
+
+// 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_; }
+
+  template <typename T>
+  T* New() {
+    size_t size = sizeof(T);
+    return new (Grow(size)) T();
+  }
+
+  template <typename T>
+  Array<T>* NewArray(size_t num_elements) {
+    // (count - 1) because Array<T> has reserved space for the first element.
+    size_t size = sizeof(Array<T>) + sizeof(T) * (num_elements - 1);
+    return new (Grow(size)) Array<T>(num_elements);
+  }
+
+  String* NewString(size_t num_chars) {
+    // (num_chars - 1) because String has reserved space for the first element.
+    size_t size = sizeof(String) + (num_chars - 1);
+    return new (Grow(size)) String(num_chars);
+  }
+
+ 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_