xpcom/glue/nsArrayEnumerator.cpp

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   2 /* ***** BEGIN LICENSE BLOCK *****
   3  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
   4  *
   5  * The contents of this file are subject to the Mozilla Public License Version
   6  * 1.1 (the "License"); you may not use this file except in compliance with
   7  * the License. You may obtain a copy of the License at
   8  * http://www.mozilla.org/MPL/
   9  *
  10  * Software distributed under the License is distributed on an "AS IS" basis,
  11  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
  12  * for the specific language governing rights and limitations under the
  13  * License.
  14  *
  15  * The Original Code is XPCOM Array implementation.
  16  *
  17  * The Initial Developer of the Original Code is
  18  * Netscape Communications Corp.
  19  * Portions created by the Initial Developer are Copyright (C) 2002
  20  * the Initial Developer. All Rights Reserved.
  21  *
  22  * Contributor(s):
  23  *   Alec Flett <alecf@netscape.com>
  24  *
  25  * Alternatively, the contents of this file may be used under the terms of
  26  * either the GNU General Public License Version 2 or later (the "GPL"), or
  27  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
  28  * in which case the provisions of the GPL or the LGPL are applicable instead
  29  * of those above. If you wish to allow use of your version of this file only
  30  * under the terms of either the GPL or the LGPL, and not to allow others to
  31  * use your version of this file under the terms of the MPL, indicate your
  32  * decision by deleting the provisions above and replace them with the notice
  33  * and other provisions required by the GPL or the LGPL. If you do not delete
  34  * the provisions above, a recipient may use your version of this file under
  35  * the terms of any one of the MPL, the GPL or the LGPL.
  36  *
  37  * ***** END LICENSE BLOCK ***** */
  38
  39 #include "nsArrayEnumerator.h"
  40
  41 #include "nsIArray.h"
  42 #include "nsISimpleEnumerator.h"
  43
  44 #include "nsCOMArray.h"
  45 #include "nsCOMPtr.h"
  46
  47 class nsSimpleArrayEnumerator : public nsISimpleEnumerator
  48 {
  49 public:
  50     // nsISupports interface
  51     NS_DECL_ISUPPORTS
  52
  53     // nsISimpleEnumerator interface
  54     NS_DECL_NSISIMPLEENUMERATOR
  55
  56     // nsSimpleArrayEnumerator methods
  57     nsSimpleArrayEnumerator(nsIArray* aValueArray) :
  58         mValueArray(aValueArray), mIndex(0) {
  59     }
  60
  61 private:
  62     ~nsSimpleArrayEnumerator() {}
  63
  64 protected:
  65     nsCOMPtr<nsIArray> mValueArray;
  66     PRUint32 mIndex;
  67 };
  68
  69 NS_IMPL_ISUPPORTS1(nsSimpleArrayEnumerator, nsISimpleEnumerator)
  70
  71 NS_IMETHODIMP
  72 nsSimpleArrayEnumerator::HasMoreElements(PRBool* aResult)
  73 {
  74     NS_PRECONDITION(aResult != 0, "null ptr");
  75     if (! aResult)
  76         return NS_ERROR_NULL_POINTER;
  77
  78     if (!mValueArray) {
  79         *aResult = PR_FALSE;
  80         return NS_OK;
  81     }
  82
  83     PRUint32 cnt;
  84     nsresult rv = mValueArray->GetLength(&cnt);
  85     if (NS_FAILED(rv)) return rv;
  86     *aResult = (mIndex < cnt);
  87     return NS_OK;
  88 }
  89
  90 NS_IMETHODIMP
  91 nsSimpleArrayEnumerator::GetNext(nsISupports** aResult)
  92 {
  93     NS_PRECONDITION(aResult != 0, "null ptr");
  94     if (! aResult)
  95         return NS_ERROR_NULL_POINTER;
  96
  97     if (!mValueArray) {
  98         *aResult = nsnull;
  99         return NS_OK;
 100     }
 101
 102     PRUint32 cnt;
 103     nsresult rv = mValueArray->GetLength(&cnt);
 104     if (NS_FAILED(rv)) return rv;
 105     if (mIndex >= cnt)
 106         return NS_ERROR_UNEXPECTED;
 107
 108     return mValueArray->QueryElementAt(mIndex++, NS_GET_IID(nsISupports), (void**)aResult);
 109 }
 110
 111 nsresult
 112 NS_NewArrayEnumerator(nsISimpleEnumerator* *result,
 113                       nsIArray* array)
 114 {
 115     nsSimpleArrayEnumerator* enumer = new nsSimpleArrayEnumerator(array);
 116     if (enumer == nsnull)
 117         return NS_ERROR_OUT_OF_MEMORY;
 118
 119     NS_ADDREF(*result = enumer);
 120     return NS_OK;
 121 }
 122
 123 ////////////////////////////////////////////////////////////////////////////////
 124
 125 // enumerator implementation for nsCOMArray
 126 // creates a snapshot of the array in question
 127 // you MUST use NS_NewArrayEnumerator to create this, so that
 128 // allocation is done correctly
 129 class nsCOMArrayEnumerator : public nsISimpleEnumerator
 130 {
 131 public:
 132     // nsISupports interface
 133     NS_DECL_ISUPPORTS
 134
 135     // nsISimpleEnumerator interface
 136     NS_DECL_NSISIMPLEENUMERATOR
 137
 138     // nsSimpleArrayEnumerator methods
 139     nsCOMArrayEnumerator() : mIndex(0) {
 140     }
 141
 142     // specialized operator to make sure we make room for mValues
 143     void* operator new (size_t size, const nsCOMArray_base& aArray) CPP_THROW_NEW;
 144     void operator delete(void* ptr) {
 145         ::operator delete(ptr);
 146     }
 147
 148 private:
 149     ~nsCOMArrayEnumerator(void);
 150
 151 protected:
 152     PRUint32 mIndex;            // current position
 153     PRUint32 mArraySize;        // size of the array
 154
 155     // this is actually bigger
 156     nsISupports* mValueArray[1];
 157 };
 158
 159 NS_IMPL_ISUPPORTS1(nsCOMArrayEnumerator, nsISimpleEnumerator)
 160
 161 nsCOMArrayEnumerator::~nsCOMArrayEnumerator()
 162 {
 163     // only release the entries that we haven't visited yet
 164     for (; mIndex < mArraySize; ++mIndex) {
 165         NS_IF_RELEASE(mValueArray[mIndex]);
 166     }
 167 }
 168
 169 NS_IMETHODIMP
 170 nsCOMArrayEnumerator::HasMoreElements(PRBool* aResult)
 171 {
 172     NS_PRECONDITION(aResult != 0, "null ptr");
 173     if (! aResult)
 174         return NS_ERROR_NULL_POINTER;
 175
 176     *aResult = (mIndex < mArraySize);
 177     return NS_OK;
 178 }
 179
 180 NS_IMETHODIMP
 181 nsCOMArrayEnumerator::GetNext(nsISupports** aResult)
 182 {
 183     NS_PRECONDITION(aResult != 0, "null ptr");
 184     if (! aResult)
 185         return NS_ERROR_NULL_POINTER;
 186
 187     if (mIndex >= mArraySize)
 188         return NS_ERROR_UNEXPECTED;
 189
 190     // pass the ownership of the reference to the caller. Since
 191     // we AddRef'ed during creation of |this|, there is no need
 192     // to AddRef here
 193     *aResult = mValueArray[mIndex++];
 194
 195     // this really isn't necessary. just pretend this happens, since
 196     // we'll never visit this value again!
 197     // mValueArray[(mIndex-1)] = nsnull;
 198
 199     return NS_OK;
 200 }
 201
 202 void*
 203 nsCOMArrayEnumerator::operator new (size_t size, const nsCOMArray_base& aArray)
 204     CPP_THROW_NEW
 205 {
 206     // create enough space such that mValueArray points to a large
 207     // enough value. Note that the initial value of size gives us
 208     // space for mValueArray[0], so we must subtract
 209     size += (aArray.Count() - 1) * sizeof(aArray[0]);
 210
 211     // do the actual allocation
 212     nsCOMArrayEnumerator * result =
 213         static_cast<nsCOMArrayEnumerator*>(::operator new(size));
 214     NS_ENSURE_TRUE(result, nsnull);
 215
 216     // now need to copy over the values, and addref each one
 217     // now this might seem like a lot of work, but we're actually just
 218     // doing all our AddRef's ahead of time since GetNext() doesn't
 219     // need to AddRef() on the way out
 220     PRUint32 i;
 221     PRUint32 max = result->mArraySize = aArray.Count();
 222     for (i = 0; i<max; i++) {
 223         result->mValueArray[i] = aArray[i];
 224         NS_IF_ADDREF(result->mValueArray[i]);
 225     }
 226
 227     return result;
 228 }
 229
 230 nsresult
 231 NS_NewArrayEnumerator(nsISimpleEnumerator* *aResult,
 232                       const nsCOMArray_base& aArray)
 233 {
 234     nsCOMArrayEnumerator *enumerator = new (aArray) nsCOMArrayEnumerator();
 235     if (!enumerator) return NS_ERROR_OUT_OF_MEMORY;
 236
 237     NS_ADDREF(*aResult = enumerator);
 238     return NS_OK;
 239 }