gecko-dev/dom/indexedDB/Key.h

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=2 et sw=2 tw=80: */
/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Indexed Database.
 *
 * The Initial Developer of the Original Code is
 * The Mozilla Foundation.
 * Portions created by the Initial Developer are Copyright (C) 2010
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Ben Turner <bent.mozilla@gmail.com>
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

#ifndef mozilla_dom_indexeddb_key_h__
#define mozilla_dom_indexeddb_key_h__

#include "mozilla/dom/indexedDB/IndexedDatabase.h"

#include "mozIStorageStatement.h"

BEGIN_INDEXEDDB_NAMESPACE

class Key
{
public:
  Key()
  {
    Unset();
  }

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

  Key& operator=(PRInt64 aInt)
  {
    SetFromInteger(aInt);
    return *this;
  }

  bool operator==(const Key& aOther) const
  {
    NS_ASSERTION(!mBuffer.IsVoid() && !aOther.mBuffer.IsVoid(),
                 "Don't compare unset keys!");

    return mBuffer.Equals(aOther.mBuffer);
  }

  bool operator!=(const Key& aOther) const
  {
    NS_ASSERTION(!mBuffer.IsVoid() && !aOther.mBuffer.IsVoid(),
                 "Don't compare unset keys!");

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

  bool operator<(const Key& aOther) const
  {
    NS_ASSERTION(!mBuffer.IsVoid() && !aOther.mBuffer.IsVoid(),
                 "Don't compare unset keys!");

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

  bool operator>(const Key& aOther) const
  {
    NS_ASSERTION(!mBuffer.IsVoid() && !aOther.mBuffer.IsVoid(),
                 "Don't compare unset keys!");

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

  bool operator<=(const Key& aOther) const
  {
    NS_ASSERTION(!mBuffer.IsVoid() && !aOther.mBuffer.IsVoid(),
                 "Don't compare unset keys!");

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

  bool operator>=(const Key& aOther) const
  {
    NS_ASSERTION(!mBuffer.IsVoid() && !aOther.mBuffer.IsVoid(),
                 "Don't compare unset keys!");

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

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

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

  bool IsFloat() const
  {
    return !mBuffer.IsVoid() && mBuffer.First() == eFloat;
  }

  double ToFloat() const
  {
    NS_ASSERTION(IsFloat(), "Why'd you call this?");
    const unsigned char* pos = BufferStart();
    double res = DecodeNumber(pos, BufferEnd());
    NS_ASSERTION(pos >= BufferEnd(), "Should consume whole buffer");
    return res;
  }

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

  void SetFromInteger(PRInt64 aInt)
  {
    mBuffer.Truncate();
    EncodeNumber(double(aInt), eFloat);
    TrimBuffer();
  }

  nsresult SetFromJSVal(JSContext* aCx,
                        const jsval aVal)
  {
    mBuffer.Truncate();

    if (JSVAL_IS_NULL(aVal) || JSVAL_IS_VOID(aVal)) {
      Unset();
      return NS_OK;
    }

    nsresult rv = EncodeJSVal(aCx, aVal, 0);
    if (NS_FAILED(rv)) {
      Unset();
      return rv;
    }
    TrimBuffer();

    return NS_OK;
  }

  nsresult ToJSVal(JSContext* aCx,
                   jsval* aVal) const
  {
    if (IsUnset()) {
      *aVal = JSVAL_VOID;
      return NS_OK;
    }

    const unsigned char* pos = BufferStart();
    nsresult rv = DecodeJSVal(pos, BufferEnd(), aCx, 0, aVal);
    NS_ENSURE_SUCCESS(rv, rv);

    NS_ASSERTION(pos >= BufferEnd(),
                 "Didn't consume whole buffer");

    return NS_OK;
  }

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

  nsresult BindToStatement(mozIStorageStatement* aStatement,
                           const nsACString& aParamName) const
  {
    nsresult rv = aStatement->BindBlobByName(aParamName,
      reinterpret_cast<const PRUint8*>(mBuffer.get()), mBuffer.Length());

    return NS_SUCCEEDED(rv) ? NS_OK : NS_ERROR_DOM_INDEXEDDB_UNKNOWN_ERR;
  }

  nsresult SetFromStatement(mozIStorageStatement* aStatement,
                            PRUint32 aIndex)
  {
    PRUint8* data;
    PRUint32 dataLength = 0;

    nsresult rv = aStatement->GetBlob(aIndex, &dataLength, &data);
    NS_ENSURE_SUCCESS(rv, NS_ERROR_DOM_INDEXEDDB_UNKNOWN_ERR);

    mBuffer.Adopt(
      reinterpret_cast<char*>(const_cast<PRUint8*>(data)), dataLength);

    return NS_OK;
  }

  static
  PRInt16 CompareKeys(Key& aFirst, Key& aSecond)
  {
    PRInt32 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());
  }

  enum {
    eTerminator = 0,
    eFloat = 1,
    eDate = 2,
    eString = 3,
    eArray = 4,
    eMaxType = eArray
  };

  // 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, const jsval aVal, PRUint8 aTypeOffset);
  void EncodeString(const nsAString& aString, PRUint8 aTypeOffset);
  void EncodeNumber(double aFloat, PRUint8 aType);

  // 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,
                              PRUint8 aTypeOffset, jsval* 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);

  nsCString mBuffer;
};

END_INDEXEDDB_NAMESPACE

#endif /* mozilla_dom_indexeddb_key_h__ */