gecko-dev/dom/indexedDB/Key.h

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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_dom_indexeddb_key_h__
#define mozilla_dom_indexeddb_key_h__

#include "js/RootingAPI.h"
#include "nsString.h"

class mozIStorageStatement;
class mozIStorageValueArray;

namespace IPC {

template <typename>
struct ParamTraits;

}  // namespace IPC

namespace mozilla {
namespace dom {
namespace indexedDB {

class Key {
  friend struct IPC::ParamTraits<Key>;

  nsCString mBuffer;

 public:
  enum {
    eTerminator = 0,
    eFloat = 0x10,
    eDate = 0x20,
    eString = 0x30,
    eBinary = 0x40,
    eArray = 0x50,
    eMaxType = eArray
  };

  static const uint8_t kMaxArrayCollapse = uint8_t(3);
  static const uint8_t kMaxRecursionDepth = uint8_t(64);

  Key() { Unset(); }

  explicit Key(const nsACString& aBuffer) : mBuffer(aBuffer) {}

  Key& operator=(const nsAString& aString) {
    SetFromString(aString);
    return *this;
  }

  Key& operator=(int64_t aInt) {
    SetFromInteger(aInt);
    return *this;
  }

  bool operator==(const Key& aOther) const {
    Assert(!mBuffer.IsVoid() && !aOther.mBuffer.IsVoid());

    return mBuffer.Equals(aOther.mBuffer);
  }

  bool operator!=(const Key& aOther) const {
    Assert(!mBuffer.IsVoid() && !aOther.mBuffer.IsVoid());

    return !mBuffer.Equals(aOther.mBuffer);
  }

  bool operator<(const Key& aOther) const {
    Assert(!mBuffer.IsVoid() && !aOther.mBuffer.IsVoid());

    return Compare(mBuffer, aOther.mBuffer) < 0;
  }

  bool operator>(const Key& aOther) const {
    Assert(!mBuffer.IsVoid() && !aOther.mBuffer.IsVoid());

    return Compare(mBuffer, aOther.mBuffer) > 0;
  }

  bool operator<=(const Key& aOther) const {
    Assert(!mBuffer.IsVoid() && !aOther.mBuffer.IsVoid());

    return Compare(mBuffer, aOther.mBuffer) <= 0;
  }

  bool operator>=(const Key& aOther) const {
    Assert(!mBuffer.IsVoid() && !aOther.mBuffer.IsVoid());

    return Compare(mBuffer, aOther.mBuffer) >= 0;
  }

  void Unset() { mBuffer.SetIsVoid(true); }

  bool IsUnset() const { return mBuffer.IsVoid(); }

  bool IsFloat() const { return !IsUnset() && *BufferStart() == eFloat; }

  bool IsDate() const { return !IsUnset() && *BufferStart() == eDate; }

  bool IsString() const { return !IsUnset() && *BufferStart() == eString; }

  bool IsBinary() const { return !IsUnset() && *BufferStart() == eBinary; }

  bool IsArray() const { return !IsUnset() && *BufferStart() >= eArray; }

  double ToFloat() const {
    Assert(IsFloat());
    const unsigned char* pos = BufferStart();
    double res = DecodeNumber(pos, BufferEnd());
    Assert(pos >= BufferEnd());
    return res;
  }

  double ToDateMsec() const {
    Assert(IsDate());
    const unsigned char* pos = BufferStart();
    double res = DecodeNumber(pos, BufferEnd());
    Assert(pos >= BufferEnd());
    return res;
  }

  void ToString(nsString& aString) const {
    Assert(IsString());
    const unsigned char* pos = BufferStart();
    DecodeString(pos, BufferEnd(), aString);
    Assert(pos >= BufferEnd());
  }

  void SetFromString(const nsAString& aString) {
    mBuffer.Truncate();
    EncodeString(aString, 0);
    TrimBuffer();
  }

  void SetFromInteger(int64_t aInt) {
    mBuffer.Truncate();
    EncodeNumber(double(aInt), eFloat);
    TrimBuffer();
  }

  nsresult SetFromJSVal(JSContext* aCx, JS::Handle<JS::Value> aVal);

  nsresult ToJSVal(JSContext* aCx, JS::MutableHandle<JS::Value> aVal) const;

  nsresult ToJSVal(JSContext* aCx, JS::Heap<JS::Value>& aVal) const;

  nsresult AppendItem(JSContext* aCx, bool aFirstOfArray,
                      JS::Handle<JS::Value> aVal);

  nsresult ToLocaleBasedKey(Key& aTarget, const nsCString& aLocale) const;

  void FinishArray() { TrimBuffer(); }

  const nsCString& GetBuffer() const { return mBuffer; }

  nsresult BindToStatement(mozIStorageStatement* aStatement,
                           const nsACString& aParamName) const;

  nsresult SetFromStatement(mozIStorageStatement* aStatement, uint32_t aIndex);

  nsresult SetFromValueArray(mozIStorageValueArray* aValues, uint32_t aIndex);

  static int16_t CompareKeys(const Key& aFirst, const Key& aSecond) {
    int32_t result = Compare(aFirst.mBuffer, aSecond.mBuffer);

    if (result < 0) {
      return -1;
    }

    if (result > 0) {
      return 1;
    }

    return 0;
  }

 private:
  const unsigned char* BufferStart() const {
    return reinterpret_cast<const unsigned char*>(mBuffer.BeginReading());
  }

  const unsigned char* BufferEnd() const {
    return reinterpret_cast<const unsigned char*>(mBuffer.EndReading());
  }

  // Encoding helper. Trims trailing zeros off of mBuffer as a post-processing
  // step.
  void TrimBuffer() {
    const char* end = mBuffer.EndReading() - 1;
    while (!*end) {
      --end;
    }

    mBuffer.Truncate(end + 1 - mBuffer.BeginReading());
  }

  // Encoding functions. These append the encoded value to the end of mBuffer
  nsresult EncodeJSVal(JSContext* aCx, JS::Handle<JS::Value> aVal,
                       uint8_t aTypeOffset);

  nsresult EncodeString(const nsAString& aString, uint8_t aTypeOffset);

  template <typename T>
  nsresult EncodeString(const T* aStart, const T* aEnd, uint8_t aTypeOffset);

  template <typename T>
  nsresult EncodeAsString(const T* aStart, const T* aEnd, uint8_t aType);

  nsresult EncodeLocaleString(const nsDependentString& aString,
                              uint8_t aTypeOffset, const nsCString& aLocale);

  void EncodeNumber(double aFloat, uint8_t aType);

  nsresult EncodeBinary(JSObject* aObject, bool aIsViewObject,
                        uint8_t aTypeOffset);

  // Decoding functions. aPos points into mBuffer and is adjusted to point
  // past the consumed value.
  static nsresult DecodeJSVal(const unsigned char*& aPos,
                              const unsigned char* aEnd, JSContext* aCx,
                              JS::MutableHandle<JS::Value> aVal);

  static void DecodeString(const unsigned char*& aPos,
                           const unsigned char* aEnd, nsString& aString);

  static double DecodeNumber(const unsigned char*& aPos,
                             const unsigned char* aEnd);

  static JSObject* DecodeBinary(const unsigned char*& aPos,
                                const unsigned char* aEnd, JSContext* aCx);

  nsresult EncodeJSValInternal(JSContext* aCx, JS::Handle<JS::Value> aVal,
                               uint8_t aTypeOffset, uint16_t aRecursionDepth);

  static nsresult DecodeJSValInternal(const unsigned char*& aPos,
                                      const unsigned char* aEnd, JSContext* aCx,
                                      uint8_t aTypeOffset,
                                      JS::MutableHandle<JS::Value> aVal,
                                      uint16_t aRecursionDepth);

  template <typename T>
  nsresult SetFromSource(T* aSource, uint32_t aIndex);

  void Assert(bool aCondition) const
#ifdef DEBUG
      ;
#else
  {
  }
#endif
};

}  // namespace indexedDB
}  // namespace dom
}  // namespace mozilla

#endif  // mozilla_dom_indexeddb_key_h__