diff -r 000000000000 -r 6474c204b198 xpcom/ds/nsStringEnumerator.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/xpcom/ds/nsStringEnumerator.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,227 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* 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 MOZ_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);
+    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);
+}
+