diff -r 000000000000 -r 6474c204b198 storage/src/Variant.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/storage/src/Variant.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,439 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: sw=2 ts=2 et lcs=trail\:.,tab\:>~ :
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_storage_Variant_h__
+#define mozilla_storage_Variant_h__
+
+#include <utility>
+
+#include "nsIVariant.h"
+#include "nsString.h"
+#include "nsTArray.h"
+
+/**
+ * This class is used by the storage module whenever an nsIVariant needs to be
+ * returned.  We provide traits for the basic sqlite types to make use easier.
+ * The following types map to the indicated sqlite type:
+ * int64_t   -> INTEGER (use IntegerVariant)
+ * double    -> FLOAT (use FloatVariant)
+ * nsString  -> TEXT (use TextVariant)
+ * nsCString -> TEXT (use UTF8TextVariant)
+ * uint8_t[] -> BLOB (use BlobVariant)
+ * nullptr   -> NULL (use NullVariant)
+ */
+
+namespace mozilla {
+namespace storage {
+
+////////////////////////////////////////////////////////////////////////////////
+//// Base Class
+
+class Variant_base : public nsIVariant
+{
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIVARIANT
+
+protected:
+  virtual ~Variant_base() { }
+};
+
+////////////////////////////////////////////////////////////////////////////////
+//// Traits
+
+/**
+ * Generics
+ */
+
+template <typename DataType>
+struct variant_traits
+{
+  static inline uint16_t type() { return nsIDataType::VTYPE_EMPTY; }
+};
+
+template <typename DataType, bool Adopting=false>
+struct variant_storage_traits
+{
+  typedef DataType ConstructorType;
+  typedef DataType StorageType;
+  static inline void storage_conversion(const ConstructorType aData, StorageType* _storage)
+  {
+    *_storage = aData;
+  }
+
+  static inline void destroy(const StorageType& _storage)
+  { }
+};
+
+#define NO_CONVERSION return NS_ERROR_CANNOT_CONVERT_DATA;
+
+template <typename DataType, bool Adopting=false>
+struct variant_integer_traits
+{
+  typedef typename variant_storage_traits<DataType, Adopting>::StorageType StorageType;
+  static inline nsresult asInt32(const StorageType &, int32_t *) { NO_CONVERSION }
+  static inline nsresult asInt64(const StorageType &, int64_t *) { NO_CONVERSION }
+};
+
+template <typename DataType, bool Adopting=false>
+struct variant_float_traits
+{
+  typedef typename variant_storage_traits<DataType, Adopting>::StorageType StorageType;
+  static inline nsresult asDouble(const StorageType &, double *) { NO_CONVERSION }
+};
+
+template <typename DataType, bool Adopting=false>
+struct variant_text_traits
+{
+  typedef typename variant_storage_traits<DataType, Adopting>::StorageType StorageType;
+  static inline nsresult asUTF8String(const StorageType &, nsACString &) { NO_CONVERSION }
+  static inline nsresult asString(const StorageType &, nsAString &) { NO_CONVERSION }
+};
+
+template <typename DataType, bool Adopting=false>
+struct variant_blob_traits
+{
+  typedef typename variant_storage_traits<DataType, Adopting>::StorageType StorageType;
+  static inline nsresult asArray(const StorageType &, uint16_t *, uint32_t *, void **)
+  { NO_CONVERSION }
+};
+
+#undef NO_CONVERSION
+
+/**
+ * INTEGER types
+ */
+
+template < >
+struct variant_traits<int64_t>
+{
+  static inline uint16_t type() { return nsIDataType::VTYPE_INT64; }
+};
+template < >
+struct variant_integer_traits<int64_t>
+{
+  static inline nsresult asInt32(int64_t aValue,
+                                 int32_t *_result)
+  {
+    if (aValue > INT32_MAX || aValue < INT32_MIN)
+      return NS_ERROR_CANNOT_CONVERT_DATA;
+
+    *_result = static_cast<int32_t>(aValue);
+    return NS_OK;
+  }
+  static inline nsresult asInt64(int64_t aValue,
+                                 int64_t *_result)
+  {
+    *_result = aValue;
+    return NS_OK;
+  }
+};
+// xpcvariant just calls get double for integers...
+template < >
+struct variant_float_traits<int64_t>
+{
+  static inline nsresult asDouble(int64_t aValue,
+                                  double *_result)
+  {
+    *_result = double(aValue);
+    return NS_OK;
+  }
+};
+
+/**
+ * FLOAT types
+ */
+
+template < >
+struct variant_traits<double>
+{
+  static inline uint16_t type() { return nsIDataType::VTYPE_DOUBLE; }
+};
+template < >
+struct variant_float_traits<double>
+{
+  static inline nsresult asDouble(double aValue,
+                                  double *_result)
+  {
+    *_result = aValue;
+    return NS_OK;
+  }
+};
+
+/**
+ * TEXT types
+ */
+
+template < >
+struct variant_traits<nsString>
+{
+  static inline uint16_t type() { return nsIDataType::VTYPE_ASTRING; }
+};
+template < >
+struct variant_storage_traits<nsString>
+{
+  typedef const nsAString & ConstructorType;
+  typedef nsString StorageType;
+  static inline void storage_conversion(ConstructorType aText, StorageType* _outData)
+  {
+    *_outData = aText;
+  }
+  static inline void destroy(const StorageType& _outData)
+  { }
+};
+template < >
+struct variant_text_traits<nsString>
+{
+  static inline nsresult asUTF8String(const nsString &aValue,
+                                      nsACString &_result)
+  {
+    CopyUTF16toUTF8(aValue, _result);
+    return NS_OK;
+  }
+  static inline nsresult asString(const nsString &aValue,
+                                  nsAString &_result)
+  {
+    _result = aValue;
+    return NS_OK;
+  }
+};
+
+template < >
+struct variant_traits<nsCString>
+{
+  static inline uint16_t type() { return nsIDataType::VTYPE_UTF8STRING; }
+};
+template < >
+struct variant_storage_traits<nsCString>
+{
+  typedef const nsACString & ConstructorType;
+  typedef nsCString StorageType;
+  static inline void storage_conversion(ConstructorType aText, StorageType* _outData)
+  {
+    *_outData = aText;
+  }
+  static inline void destroy(const StorageType &aData)
+  { }
+};
+template < >
+struct variant_text_traits<nsCString>
+{
+  static inline nsresult asUTF8String(const nsCString &aValue,
+                                      nsACString &_result)
+  {
+    _result = aValue;
+    return NS_OK;
+  }
+  static inline nsresult asString(const nsCString &aValue,
+                                  nsAString &_result)
+  {
+    CopyUTF8toUTF16(aValue, _result);
+    return NS_OK;
+  }
+};
+
+/**
+ * BLOB types
+ */
+
+template < >
+struct variant_traits<uint8_t[]>
+{
+  static inline uint16_t type() { return nsIDataType::VTYPE_ARRAY; }
+};
+template < >
+struct variant_storage_traits<uint8_t[], false>
+{
+  typedef std::pair<const void *, int> ConstructorType;
+  typedef FallibleTArray<uint8_t> StorageType;
+  static inline void storage_conversion(ConstructorType aBlob, StorageType* _outData)
+  {
+    _outData->Clear();
+    _outData->SetCapacity(aBlob.second);
+    (void)_outData->AppendElements(static_cast<const uint8_t *>(aBlob.first),
+                                   aBlob.second);
+  }
+  static inline void destroy(const StorageType& _outData)
+  { }
+};
+template < >
+struct variant_storage_traits<uint8_t[], true>
+{
+  typedef std::pair<uint8_t *, int> ConstructorType;
+  typedef std::pair<uint8_t *, int> StorageType;
+  static inline void storage_conversion(ConstructorType aBlob, StorageType* _outData)
+  {
+    *_outData = aBlob;
+  }
+  static inline void destroy(StorageType &aData)
+  {
+    if (aData.first) {
+      NS_Free(aData.first);
+      aData.first = nullptr;
+    }
+  }
+};
+template < >
+struct variant_blob_traits<uint8_t[], false>
+{
+  static inline nsresult asArray(FallibleTArray<uint8_t> &aData,
+                                 uint16_t *_type,
+                                 uint32_t *_size,
+                                 void **_result)
+  {
+    // For empty blobs, we return nullptr.
+    if (aData.Length() == 0) {
+      *_result = nullptr;
+      *_type = nsIDataType::VTYPE_UINT8;
+      *_size = 0;
+      return NS_OK;
+    }
+
+    // Otherwise, we copy the array.
+    *_result = nsMemory::Clone(aData.Elements(), aData.Length() * sizeof(uint8_t));
+    NS_ENSURE_TRUE(*_result, NS_ERROR_OUT_OF_MEMORY);
+
+    // Set type and size
+    *_type = nsIDataType::VTYPE_UINT8;
+    *_size = aData.Length();
+    return NS_OK;
+  }
+};
+
+template < >
+struct variant_blob_traits<uint8_t[], true>
+{
+  static inline nsresult asArray(std::pair<uint8_t *, int> &aData,
+                                 uint16_t *_type,
+                                 uint32_t *_size,
+                                 void **_result)
+  {
+    // For empty blobs, we return nullptr.
+    if (aData.second == 0) {
+      *_result = nullptr;
+      *_type = nsIDataType::VTYPE_UINT8;
+      *_size = 0;
+      return NS_OK;
+    }
+
+    // Otherwise, transfer the data out.
+    *_result = aData.first;
+    aData.first = nullptr;
+    MOZ_ASSERT(*_result); // We asked for it twice, better not use adopting!
+
+    // Set type and size
+    *_type = nsIDataType::VTYPE_UINT8;
+    *_size = aData.second;
+    return NS_OK;
+  }
+};
+
+/**
+ * nullptr type
+ */
+
+class NullVariant : public Variant_base
+{
+public:
+  NS_IMETHOD GetDataType(uint16_t *_type)
+  {
+    NS_ENSURE_ARG_POINTER(_type);
+    *_type = nsIDataType::VTYPE_EMPTY;
+    return NS_OK;
+  }
+
+  NS_IMETHOD GetAsAUTF8String(nsACString &_str)
+  {
+    // Return a void string.
+    _str.Truncate(0);
+    _str.SetIsVoid(true);
+    return NS_OK;
+  }
+
+  NS_IMETHOD GetAsAString(nsAString &_str)
+  {
+    // Return a void string.
+    _str.Truncate(0);
+    _str.SetIsVoid(true);
+    return NS_OK;
+  }
+};
+
+////////////////////////////////////////////////////////////////////////////////
+//// Template Implementation
+
+template <typename DataType, bool Adopting=false>
+class Variant : public Variant_base
+{
+  ~Variant()
+  {
+    variant_storage_traits<DataType, Adopting>::destroy(mData);
+  }
+
+public:
+  Variant(const typename variant_storage_traits<DataType, Adopting>::ConstructorType aData)
+  {
+    variant_storage_traits<DataType, Adopting>::storage_conversion(aData, &mData);
+  }
+
+  NS_IMETHOD GetDataType(uint16_t *_type)
+  {
+    *_type = variant_traits<DataType>::type();
+    return NS_OK;
+  }
+  NS_IMETHOD GetAsInt32(int32_t *_integer)
+  {
+    return variant_integer_traits<DataType, Adopting>::asInt32(mData, _integer);
+  }
+
+  NS_IMETHOD GetAsInt64(int64_t *_integer)
+  {
+    return variant_integer_traits<DataType, Adopting>::asInt64(mData, _integer);
+  }
+
+  NS_IMETHOD GetAsDouble(double *_double)
+  {
+    return variant_float_traits<DataType, Adopting>::asDouble(mData, _double);
+  }
+
+  NS_IMETHOD GetAsAUTF8String(nsACString &_str)
+  {
+    return variant_text_traits<DataType, Adopting>::asUTF8String(mData, _str);
+  }
+
+  NS_IMETHOD GetAsAString(nsAString &_str)
+  {
+    return variant_text_traits<DataType, Adopting>::asString(mData, _str);
+  }
+
+  NS_IMETHOD GetAsArray(uint16_t *_type,
+                        nsIID *,
+                        uint32_t *_size,
+                        void **_data)
+  {
+    return variant_blob_traits<DataType, Adopting>::asArray(mData, _type, _size, _data);
+  }
+
+private:
+  typename variant_storage_traits<DataType, Adopting>::StorageType mData;
+};
+
+////////////////////////////////////////////////////////////////////////////////
+//// Handy typedefs!  Use these for the right mapping.
+
+typedef Variant<int64_t> IntegerVariant;
+typedef Variant<double> FloatVariant;
+typedef Variant<nsString> TextVariant;
+typedef Variant<nsCString> UTF8TextVariant;
+typedef Variant<uint8_t[], false> BlobVariant;
+typedef Variant<uint8_t[], true> AdoptedBlobVariant;
+
+} // namespace storage
+} // namespace mozilla
+
+#include "Variant_inl.h"
+
+#endif // mozilla_storage_Variant_h__