nsStringEnumerator.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 "nsStringEnumerator.h"
#include "nsISimpleEnumerator.h"
#include "nsSupportsPrimitives.h"
#include "mozilla/Attributes.h"
#include "nsTArray.h"

//
// nsStringEnumerator
//

class nsStringEnumerator final
  : public nsIStringEnumerator
  , public nsIUTF8StringEnumerator
  , public nsISimpleEnumerator
{
public:
  nsStringEnumerator(const nsTArray<nsString>* aArray, bool aOwnsArray)
    : mArray(aArray)
    , mIndex(0)
    , mOwnsArray(aOwnsArray)
    , mIsUnicode(true)
  {}

  nsStringEnumerator(const nsTArray<nsCString>* aArray, bool aOwnsArray)
    : mCArray(aArray)
    , mIndex(0)
    , mOwnsArray(aOwnsArray)
    , mIsUnicode(false)
  {}

  nsStringEnumerator(const nsTArray<nsString>* aArray, nsISupports* aOwner)
    : mArray(aArray)
    , mIndex(0)
    , mOwner(aOwner)
    , mOwnsArray(false)
    , mIsUnicode(true)
  {}

  nsStringEnumerator(const nsTArray<nsCString>* aArray, nsISupports* aOwner)
    : mCArray(aArray)
    , mIndex(0)
    , mOwner(aOwner)
    , mOwnsArray(false)
    , mIsUnicode(false)
  {}

  NS_DECL_ISUPPORTS
  NS_DECL_NSIUTF8STRINGENUMERATOR

  // have to declare nsIStringEnumerator manually, because of
  // overlapping method names
  NS_IMETHOD GetNext(nsAString& aResult) override;
  NS_DECL_NSISIMPLEENUMERATOR

private:
  ~nsStringEnumerator()
  {
    if (mOwnsArray) {
      // const-casting is safe here, because the NS_New*
      // constructors make sure mOwnsArray is consistent with
      // the constness of the objects
      if (mIsUnicode) {
        delete const_cast<nsTArray<nsString>*>(mArray);
      } else {
        delete const_cast<nsTArray<nsCString>*>(mCArray);
      }
    }
  }

  union
  {
    const nsTArray<nsString>* mArray;
    const nsTArray<nsCString>* mCArray;
  };

  inline uint32_t Count()
  {
    return mIsUnicode ? mArray->Length() : mCArray->Length();
  }

  uint32_t mIndex;

  // the owner allows us to hold a strong reference to the object
  // that owns the array. Having a non-null value in mOwner implies
  // that mOwnsArray is false, because we rely on the real owner
  // to release the array
  nsCOMPtr<nsISupports> mOwner;
  bool mOwnsArray;
  bool mIsUnicode;
};

NS_IMPL_ISUPPORTS(nsStringEnumerator,
                  nsIStringEnumerator,
                  nsIUTF8StringEnumerator,
                  nsISimpleEnumerator)

NS_IMETHODIMP
nsStringEnumerator::HasMore(bool* aResult)
{
  *aResult = mIndex < Count();
  return NS_OK;
}

NS_IMETHODIMP
nsStringEnumerator::HasMoreElements(bool* aResult)
{
  return HasMore(aResult);
}

NS_IMETHODIMP
nsStringEnumerator::GetNext(nsISupports** aResult)
{
  if (mIsUnicode) {
    nsSupportsStringImpl* stringImpl = new nsSupportsStringImpl();
    if (!stringImpl) {
      return NS_ERROR_OUT_OF_MEMORY;
    }

    stringImpl->SetData(mArray->ElementAt(mIndex++));
    *aResult = stringImpl;
  } else {
    nsSupportsCStringImpl* cstringImpl = new nsSupportsCStringImpl();
    if (!cstringImpl) {
      return NS_ERROR_OUT_OF_MEMORY;
    }

    cstringImpl->SetData(mCArray->ElementAt(mIndex++));
    *aResult = cstringImpl;
  }
  NS_ADDREF(*aResult);
  return NS_OK;
}

NS_IMETHODIMP
nsStringEnumerator::GetNext(nsAString& aResult)
{
  if (NS_WARN_IF(mIndex >= Count())) {
    return NS_ERROR_UNEXPECTED;
  }

  if (mIsUnicode) {
    aResult = mArray->ElementAt(mIndex++);
  } else {
    CopyUTF8toUTF16(mCArray->ElementAt(mIndex++), aResult);
  }

  return NS_OK;
}

NS_IMETHODIMP
nsStringEnumerator::GetNext(nsACString& aResult)
{
  if (NS_WARN_IF(mIndex >= Count())) {
    return NS_ERROR_UNEXPECTED;
  }

  if (mIsUnicode) {
    CopyUTF16toUTF8(mArray->ElementAt(mIndex++), aResult);
  } else {
    aResult = mCArray->ElementAt(mIndex++);
  }

  return NS_OK;
}

template<class T>
static inline nsresult
StringEnumeratorTail(T** aResult)
{
  if (!*aResult) {
    return NS_ERROR_OUT_OF_MEMORY;
  }
  NS_ADDREF(*aResult);
  return NS_OK;
}

//
// constructors
//

nsresult
NS_NewStringEnumerator(nsIStringEnumerator** aResult,
                       const nsTArray<nsString>* aArray, nsISupports* aOwner)
{
  if (NS_WARN_IF(!aResult) || NS_WARN_IF(!aArray)) {
    return NS_ERROR_INVALID_ARG;
  }

  *aResult = new nsStringEnumerator(aArray, aOwner);
  return StringEnumeratorTail(aResult);
}


nsresult
NS_NewUTF8StringEnumerator(nsIUTF8StringEnumerator** aResult,
                           const nsTArray<nsCString>* aArray,
                           nsISupports* aOwner)
{
  if (NS_WARN_IF(!aResult) || NS_WARN_IF(!aArray)) {
    return NS_ERROR_INVALID_ARG;
  }

  *aResult = new nsStringEnumerator(aArray, aOwner);
  return StringEnumeratorTail(aResult);
}

nsresult
NS_NewAdoptingStringEnumerator(nsIStringEnumerator** aResult,
                               nsTArray<nsString>* aArray)
{
  if (NS_WARN_IF(!aResult) || NS_WARN_IF(!aArray)) {
    return NS_ERROR_INVALID_ARG;
  }

  *aResult = new nsStringEnumerator(aArray, true);
  return StringEnumeratorTail(aResult);
}

nsresult
NS_NewAdoptingUTF8StringEnumerator(nsIUTF8StringEnumerator** aResult,
                                   nsTArray<nsCString>* aArray)
{
  if (NS_WARN_IF(!aResult) || NS_WARN_IF(!aArray)) {
    return NS_ERROR_INVALID_ARG;
  }

  *aResult = new nsStringEnumerator(aArray, true);
  return StringEnumeratorTail(aResult);
}

// const ones internally just forward to the non-const equivalents
nsresult
NS_NewStringEnumerator(nsIStringEnumerator** aResult,
                       const nsTArray<nsString>* aArray)
{
  if (NS_WARN_IF(!aResult) || NS_WARN_IF(!aArray)) {
    return NS_ERROR_INVALID_ARG;
  }

  *aResult = new nsStringEnumerator(aArray, false);
  return StringEnumeratorTail(aResult);
}

nsresult
NS_NewUTF8StringEnumerator(nsIUTF8StringEnumerator** aResult,
                           const nsTArray<nsCString>* aArray)
{
  if (NS_WARN_IF(!aResult) || NS_WARN_IF(!aArray)) {
    return NS_ERROR_INVALID_ARG;
  }

  *aResult = new nsStringEnumerator(aArray, false);
  return StringEnumeratorTail(aResult);
}