gecko-dev/dom/smil/nsSMILValue.cpp

/* -*- 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/. */

#include "nsSMILValue.h"
#include "nsDebug.h"
#include <string.h>

//----------------------------------------------------------------------
// Public methods

nsSMILValue::nsSMILValue(const nsISMILType* aType)
  : mType(nsSMILNullType::Singleton())
{
  if (!aType) {
    NS_ERROR("Trying to construct nsSMILValue with null mType pointer");
    return;
  }

  InitAndCheckPostcondition(aType);
}

nsSMILValue::nsSMILValue(const nsSMILValue& aVal)
  : mType(nsSMILNullType::Singleton())
{
  InitAndCheckPostcondition(aVal.mType);
  mType->Assign(*this, aVal);
}

const nsSMILValue&
nsSMILValue::operator=(const nsSMILValue& aVal)
{
  if (&aVal == this)
    return *this;

  if (mType != aVal.mType) {
    DestroyAndReinit(aVal.mType);
  }

  mType->Assign(*this, aVal);

  return *this;
}

bool
nsSMILValue::operator==(const nsSMILValue& aVal) const
{
  if (&aVal == this)
    return true;

  return mType == aVal.mType && mType->IsEqual(*this, aVal);
}

void
nsSMILValue::Swap(nsSMILValue& aOther)
{
  nsSMILValue tmp;
  memcpy(&tmp,    &aOther, sizeof(nsSMILValue));  // tmp    = aOther
  memcpy(&aOther, this,    sizeof(nsSMILValue));  // aOther = this
  memcpy(this,    &tmp,    sizeof(nsSMILValue));  // this   = tmp

  // |tmp| is about to die -- we need to clear its mType, so that its
  // destructor doesn't muck with the data we just transferred out of it.
  tmp.mType = nsSMILNullType::Singleton();
}

nsresult
nsSMILValue::Add(const nsSMILValue& aValueToAdd, uint32_t aCount)
{
  if (aValueToAdd.mType != mType) {
    NS_ERROR("Trying to add incompatible types");
    return NS_ERROR_FAILURE;
  }

  return mType->Add(*this, aValueToAdd, aCount);
}

nsresult
nsSMILValue::SandwichAdd(const nsSMILValue& aValueToAdd)
{
  if (aValueToAdd.mType != mType) {
    NS_ERROR("Trying to add incompatible types");
    return NS_ERROR_FAILURE;
  }

  return mType->SandwichAdd(*this, aValueToAdd);
}

nsresult
nsSMILValue::ComputeDistance(const nsSMILValue& aTo, double& aDistance) const
{
  if (aTo.mType != mType) {
    NS_ERROR("Trying to calculate distance between incompatible types");
    return NS_ERROR_FAILURE;
  }

  return mType->ComputeDistance(*this, aTo, aDistance);
}

nsresult
nsSMILValue::Interpolate(const nsSMILValue& aEndVal,
                         double aUnitDistance,
                         nsSMILValue& aResult) const
{
  if (aEndVal.mType != mType) {
    NS_ERROR("Trying to interpolate between incompatible types");
    return NS_ERROR_FAILURE;
  }

  if (aResult.mType != mType) {
    // Outparam has wrong type
    aResult.DestroyAndReinit(mType);
  }

  return mType->Interpolate(*this, aEndVal, aUnitDistance, aResult);
}

//----------------------------------------------------------------------
// Helper methods

// Wrappers for nsISMILType::Init & ::Destroy that verify their postconditions
void
nsSMILValue::InitAndCheckPostcondition(const nsISMILType* aNewType)
{
  aNewType->Init(*this);
  MOZ_ASSERT(mType == aNewType,
             "Post-condition of Init failed. nsSMILValue is invalid");
}
                
void
nsSMILValue::DestroyAndCheckPostcondition()
{
  mType->Destroy(*this);
  MOZ_ASSERT(IsNull(),
             "Post-condition of Destroy failed. "
             "nsSMILValue not null after destroying");
}

void
nsSMILValue::DestroyAndReinit(const nsISMILType* aNewType)
{
  DestroyAndCheckPostcondition();
  InitAndCheckPostcondition(aNewType);
}