Bug 875557 - Make nsDeque infallible by default. r=bsmedberg

Also remove some unused return values.

xpcom/glue/nsDeque.cpp

@@ -103,28 +103,23 @@ void nsDeque::SetDeallocator(nsDequeFunctor* aDeallocator){
 
 /**
  * Remove all items from container without destroying them.
- *
- * @return  *this
  */
-nsDeque& nsDeque::Empty() {
+void nsDeque::Empty() {
   if (mSize && mData) {
     memset(mData, 0, mCapacity*sizeof(mData));
   }
   mSize=0;
   mOrigin=0;
-  return *this;
 }
 
 /**
  * Remove and delete all items from container
- *
- * @return  *this
  */
-nsDeque& nsDeque::Erase() {
+void nsDeque::Erase() {
   if (mDeallocator && mSize) {
     ForEach(*mDeallocator);
   }
-  return Empty();
+  Empty();
 }
 
 /**
@@ -132,9 +127,6 @@ nsDeque& nsDeque::Erase() {
  * Elements in the deque are resequenced so that elements
  * in the deque are stored sequentially
  *
- * If the deque actually overflows, there's very little we can do.
- * Perhaps this function should return bool/nsresult indicating success/failure.
- *
  * @return  whether growing succeeded
  */
 bool nsDeque::GrowCapacity() {
@@ -171,15 +163,14 @@ bool nsDeque::GrowCapacity() {
  * underlying buffer to resize.
  *
  * @param   aItem: new item to be added to deque
- * @return  *this
  */
-nsDeque& nsDeque::Push(void* aItem) {
+bool nsDeque::Push(void* aItem, const fallible_t&) {
   if (mSize==mCapacity && !GrowCapacity()) {
-    return *this;
+    return false;
   }
   mData[modulus(mOrigin + mSize, mCapacity)]=aItem;
   mSize++;
-  return *this;
+  return true;
 }
 
 /**
@@ -213,22 +204,20 @@ nsDeque& nsDeque::Push(void* aItem) {
  * and increment size: 9. (C is no longer out of bounds)
  * --
  * @param   aItem: new item to be added to deque
- * @return  *this
  */
-nsDeque& nsDeque::PushFront(void* aItem) {
+bool nsDeque::PushFront(void* aItem, const fallible_t&) {
   mOrigin--;
   modasgn(mOrigin,mCapacity);
   if (mSize==mCapacity) {
     if (!GrowCapacity()) {
-      NS_WARNING("out of memory");
-      return *this;
+      return false;
     }
     /* Comments explaining this are above*/
     mData[mSize]=mData[mOrigin];
   }
   mData[mOrigin]=aItem;
   mSize++;
-  return *this;
+  return true;
 }
 
 /**

xpcom/glue/nsDeque.h

@@ -25,7 +25,9 @@
 #define _NSDEQUE
 
 #include "nscore.h"
+#include "nsDebug.h"
 #include "mozilla/Attributes.h"
+#include "mozilla/fallible.h"
 
 /**
  * The nsDequeFunctor class is used when you want to create
@@ -58,6 +60,7 @@ class nsDequeIterator;
 
 class NS_COM_GLUE nsDeque {
   friend class nsDequeIterator;
+  typedef mozilla::fallible_t fallible_t;
   public:
    nsDeque(nsDequeFunctor* aDeallocator = nullptr);
   ~nsDeque();
@@ -74,17 +77,27 @@ class NS_COM_GLUE nsDeque {
    * Appends new member at the end of the deque.
    *
    * @param   item to store in deque
-   * @return  *this
    */
-  nsDeque& Push(void* aItem);
+  void Push(void* aItem) {
+    if (!Push(aItem, fallible_t())) {
+      NS_RUNTIMEABORT("OOM");
+    }
+  }
+
+  bool Push(void* aItem, const fallible_t&) NS_WARN_UNUSED_RESULT;
 
   /**
    * Inserts new member at the front of the deque.
    *
    * @param   item to store in deque
-   * @return  *this
    */
-  nsDeque& PushFront(void* aItem);
+  void PushFront(void* aItem) {
+    if (!PushFront(aItem, fallible_t())) {
+      NS_RUNTIMEABORT("OOM");
+    }
+  }
+
+  bool PushFront(void* aItem, const fallible_t&) NS_WARN_UNUSED_RESULT;
 
   /**
    * Remove and return the last item in the container.
@@ -132,19 +145,15 @@ class NS_COM_GLUE nsDeque {
 
   /**
    * Remove all items from container without destroying them.
-   *
-   * @return  *this
    */
-  nsDeque& Empty();
+  void Empty();
 
   /**
    * Remove and delete all items from container.
    * Deletes are handled by the deallocator nsDequeFunctor
    * which is specified at deque construction.
-   *
-   * @return  *this
    */
-  nsDeque& Erase();
+  void Erase();
 
   /**
    * Creates a new iterator, pointing to the first
@@ -163,13 +172,13 @@ class NS_COM_GLUE nsDeque {
   nsDequeIterator End() const;
 
   void* Last() const;
+
   /**
    * Call this method when you want to iterate all the
    * members of the container, passing a functor along
    * to call your code.
    *
    * @param   aFunctor object to call for each member
-   * @return  *this
    */
   void ForEach(nsDequeFunctor& aFunctor) const;