1 files changed, 213 insertions, 0 deletions
diff --git a/xpcom/glue/nsArrayEnumerator.cpp b/xpcom/glue/nsArrayEnumerator.cpp
new file mode 100644
index 000000000..2d2ef6da7
--- /dev/null
+++ b/xpcom/glue/nsArrayEnumerator.cpp
@@ -0,0 +1,213 @@
+/* -*- 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 "mozilla/Attributes.h"
+
+#include "nsArrayEnumerator.h"
+
+#include "nsIArray.h"
+#include "nsISimpleEnumerator.h"
+
+#include "nsCOMArray.h"
+#include "nsCOMPtr.h"
+#include "mozilla/RefPtr.h"
+
+class nsSimpleArrayEnumerator final : public nsISimpleEnumerator
+{
+public:
+  // nsISupports interface
+  NS_DECL_ISUPPORTS
+
+  // nsISimpleEnumerator interface
+  NS_DECL_NSISIMPLEENUMERATOR
+
+  // nsSimpleArrayEnumerator methods
+  explicit nsSimpleArrayEnumerator(nsIArray* aValueArray)
+    : mValueArray(aValueArray)
+    , mIndex(0)
+  {
+  }
+
+private:
+  ~nsSimpleArrayEnumerator() {}
+
+protected:
+  nsCOMPtr<nsIArray> mValueArray;
+  uint32_t mIndex;
+};
+
+NS_IMPL_ISUPPORTS(nsSimpleArrayEnumerator, nsISimpleEnumerator)
+
+NS_IMETHODIMP
+nsSimpleArrayEnumerator::HasMoreElements(bool* aResult)
+{
+  NS_PRECONDITION(aResult != 0, "null ptr");
+  if (!aResult) {
+    return NS_ERROR_NULL_POINTER;
+  }
+
+  if (!mValueArray) {
+    *aResult = false;
+    return NS_OK;
+  }
+
+  uint32_t cnt;
+  nsresult rv = mValueArray->GetLength(&cnt);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  *aResult = (mIndex < cnt);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSimpleArrayEnumerator::GetNext(nsISupports** aResult)
+{
+  NS_PRECONDITION(aResult != 0, "null ptr");
+  if (!aResult) {
+    return NS_ERROR_NULL_POINTER;
+  }
+
+  if (!mValueArray) {
+    *aResult = nullptr;
+    return NS_OK;
+  }
+
+  uint32_t cnt;
+  nsresult rv = mValueArray->GetLength(&cnt);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  if (mIndex >= cnt) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  return mValueArray->QueryElementAt(mIndex++, NS_GET_IID(nsISupports),
+                                     (void**)aResult);
+}
+
+nsresult
+NS_NewArrayEnumerator(nsISimpleEnumerator** aResult, nsIArray* aArray)
+{
+  RefPtr<nsSimpleArrayEnumerator> enumer = new nsSimpleArrayEnumerator(aArray);
+  enumer.forget(aResult);
+  return NS_OK;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+// enumerator implementation for nsCOMArray
+// creates a snapshot of the array in question
+// you MUST use NS_NewArrayEnumerator to create this, so that
+// allocation is done correctly
+class nsCOMArrayEnumerator final : public nsISimpleEnumerator
+{
+public:
+  // nsISupports interface
+  NS_DECL_ISUPPORTS
+
+  // nsISimpleEnumerator interface
+  NS_DECL_NSISIMPLEENUMERATOR
+
+  // nsSimpleArrayEnumerator methods
+  nsCOMArrayEnumerator() : mIndex(0) {}
+
+  // specialized operator to make sure we make room for mValues
+  void* operator new(size_t aSize, const nsCOMArray_base& aArray) CPP_THROW_NEW;
+  void operator delete(void* aPtr) { ::operator delete(aPtr); }
+
+private:
+  ~nsCOMArrayEnumerator(void);
+
+protected:
+  uint32_t mIndex;            // current position
+  uint32_t mArraySize;        // size of the array
+
+  // this is actually bigger
+  nsISupports* mValueArray[1];
+};
+
+NS_IMPL_ISUPPORTS(nsCOMArrayEnumerator, nsISimpleEnumerator)
+
+nsCOMArrayEnumerator::~nsCOMArrayEnumerator()
+{
+  // only release the entries that we haven't visited yet
+  for (; mIndex < mArraySize; ++mIndex) {
+    NS_IF_RELEASE(mValueArray[mIndex]);
+  }
+}
+
+NS_IMETHODIMP
+nsCOMArrayEnumerator::HasMoreElements(bool* aResult)
+{
+  NS_PRECONDITION(aResult != 0, "null ptr");
+  if (!aResult) {
+    return NS_ERROR_NULL_POINTER;
+  }
+
+  *aResult = (mIndex < mArraySize);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsCOMArrayEnumerator::GetNext(nsISupports** aResult)
+{
+  NS_PRECONDITION(aResult != 0, "null ptr");
+  if (!aResult) {
+    return NS_ERROR_NULL_POINTER;
+  }
+
+  if (mIndex >= mArraySize) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  // pass the ownership of the reference to the caller. Since
+  // we AddRef'ed during creation of |this|, there is no need
+  // to AddRef here
+  *aResult = mValueArray[mIndex++];
+
+  // this really isn't necessary. just pretend this happens, since
+  // we'll never visit this value again!
+  // mValueArray[(mIndex-1)] = nullptr;
+
+  return NS_OK;
+}
+
+void*
+nsCOMArrayEnumerator::operator new(size_t aSize,
+                                   const nsCOMArray_base& aArray) CPP_THROW_NEW
+{
+  // create enough space such that mValueArray points to a large
+  // enough value. Note that the initial value of aSize gives us
+  // space for mValueArray[0], so we must subtract
+  aSize += (aArray.Count() - 1) * sizeof(aArray[0]);
+
+  // do the actual allocation
+  nsCOMArrayEnumerator* result =
+    static_cast<nsCOMArrayEnumerator*>(::operator new(aSize));
+
+  // now need to copy over the values, and addref each one
+  // now this might seem like a lot of work, but we're actually just
+  // doing all our AddRef's ahead of time since GetNext() doesn't
+  // need to AddRef() on the way out
+  uint32_t i;
+  uint32_t max = result->mArraySize = aArray.Count();
+  for (i = 0; i < max; ++i) {
+    result->mValueArray[i] = aArray[i];
+    NS_IF_ADDREF(result->mValueArray[i]);
+  }
+
+  return result;
+}
+
+nsresult
+NS_NewArrayEnumerator(nsISimpleEnumerator** aResult,
+                      const nsCOMArray_base& aArray)
+{
+  RefPtr<nsCOMArrayEnumerator> enumerator = new (aArray) nsCOMArrayEnumerator();
+  enumerator.forget(aResult);
+  return NS_OK;
+}