not part of build, more for bug 162115:

- fix some spelling, add documentation
- add NS_NewArray(), including one that takes an existing nsCOMArray<T>
- implement copy constructor for nsCOMArray_base, so that NS_NewArray can work
not part of build

xpcom/glue/nsCOMArray.cpp

@@ -38,8 +38,27 @@
 
 #include "nsCOMArray.h"
 
+static PRBool AddRefObjects(void* aElement, void*);
+static PRBool ReleaseObjects(void* aElement, void*);
+
+
 // implementations of non-trivial methods in nsCOMArray_base
 
+// copy constructor - we can't just memcpy here, because
+// we have to make sure we own our own array buffer, and that each
+// object gets another AddRef()
+nsCOMArray_base::nsCOMArray_base(const nsCOMArray_base& aOther)
+{
+    PRInt32 count = aOther.Count();
+    // make sure we do only one allocation
+    mArray.SizeTo(count);
+    
+    PRInt32 i;
+    for (i=0; i<count; i++) {
+        ReplaceObjectAt(aOther[i], i);
+    }
+}
+
 PRBool
 nsCOMArray_base::InsertObjectAt(nsISupports* aObject, PRInt32 aIndex) {
     PRBool result = mArray.InsertElementAt(aObject, aIndex);
@@ -98,8 +117,19 @@ nsCOMArray_base::RemoveObjectAt(PRInt32 aIndex)
     return PR_FALSE;
 }
 
-static PRBool
-ClearObjectsCallback(void* aElement, void*)
+
+// useful for copy constructors
+PRBool
+AddRefObjects(void* aElement, void*)
+{
+    nsISupports* element = NS_STATIC_CAST(nsISupports*,aElement);
+    NS_IF_ADDREF(element);
+    return PR_TRUE;
+}
+
+// useful for destructors
+PRBool
+ReleaseObjects(void* aElement, void*)
 {
     nsISupports* element = NS_STATIC_CAST(nsISupports*, aElement);
     NS_IF_RELEASE(element);
@@ -109,6 +139,7 @@ ClearObjectsCallback(void* aElement, void*)
 void
 nsCOMArray_base::Clear()
 {
-    mArray.EnumerateForwards(ClearObjectsCallback, nsnull);
+    mArray.EnumerateForwards(ReleaseObjects, nsnull);
     mArray.Clear();
 }
+

xpcom/glue/nsCOMArray.h

@@ -42,6 +42,8 @@
 #include "nsVoidArray.h"
 #include "nsISupports.h"
 
+// See below for the definition of nsCOMArray<T>
+
 // a class that's nsISupports-specific, so that we can contain the
 // work of this class in the XPCOM dll
 class NS_COM nsCOMArray_base
@@ -49,6 +51,7 @@ class NS_COM nsCOMArray_base
 protected:
     nsCOMArray_base() {}
     nsCOMArray_base(PRInt32 aCount) : mArray(aCount) {}
+    nsCOMArray_base(const nsCOMArray_base& other);
 
     nsISupports* ObjectAt(PRInt32 aIndex) const {
         return NS_STATIC_CAST(nsISupports*, mArray.ElementAt(aIndex));
@@ -88,19 +91,35 @@ protected:
     nsVoidArray mArray;
 
     // don't implement these, defaults will muck with refcounts!
-    nsCOMArray_base(const nsCOMArray_base& other);
     nsCOMArray_base& operator=(const nsCOMArray_base& other);
 };
 
 // a non-XPCOM, refcounting array of XPCOM objects
 // used as a member variable or stack variable - this object is NOT
 // refcounted, but the objects that it holds are
+//
+// most of the read-only accessors like ObjectAt()/etc do NOT refcount
+// on the way out. This means that you can do one of two things:
+//
+// * does an addref, but holds onto a reference
+// nsCOMPtr<T> foo = array[i];
+//
+// * avoids the refcount, but foo might go stale if array[i] is ever
+// * modified/removed. Be careful not to NS_RELEASE(foo)!
+// T* foo = array[i];
+//
+// This array will accept null as an argument for any object, and will
+// store null in the array, just like nsVoidArray. But that also means
+// that methods like ObjectAt() may return null when refering to an
+// existing, but null entry in the array.
 template <class T>
 class nsCOMArray : protected nsCOMArray_base
 {
  public:
     nsCOMArray() {}
     nsCOMArray(PRInt32 aCount) : nsCOMArray_base(aCount) {}
+    
+    nsCOMArray(const nsCOMArray_base& aOther) : nsCOMArray_base(aOther) { }
 
     ~nsCOMArray() {}
 
@@ -108,50 +127,72 @@ class nsCOMArray : protected nsCOMArray_base
     T* ObjectAt(PRInt32 aIndex) const {
         return NS_STATIC_CAST(T*,nsCOMArray_base::ObjectAt(aIndex));
     }
-    
+
+    // indexing operator for syntactic sugar
     T* operator[](PRInt32 aIndex) const {
         return ObjectAt(aIndex);
     }
 
+    // index of the element in question.. does NOT refcount
     PRInt32 IndexOf(T* aObject) {
         return nsCOMArray_base::IndexOf(aObject);
     }
-    
+
+    // inserts the object at aIndex, and move all objects after aIndex
+    // to the right
     PRBool InsertObjectAt(T* aObject, PRInt32 aIndex) {
         return nsCOMArray_base::InsertObjectAt(aObject, aIndex);
     }
-    
+
+    // replaces an existing element. Warning: if the array grows,
+    // the newly created entries will all be null
     PRBool ReplaceObjectAt(T* aObject, PRInt32 aIndex) {
         return nsCOMArray_base::ReplaceObjectAt(aObject, aIndex);
     }
 
     // override nsVoidArray stuff so that they can be accessed by
     // other methods
+
+    // elements in the array (including null elements!)
     PRInt32 Count() const {
         return nsCOMArray_base::Count();
     }
 
+    // remove all elements in the array, and call NS_RELEASE on each one
     void Clear() {
         nsCOMArray_base::Clear();
     }
 
-    PRBool EnumerateForwards(nsVoidArrayEnumFunc aFunc, void* aData) {
-        return nsCOMArray_base::EnumerateForwards(aFunc, aData);
-    }
+    // Enumerator callback function. Return PR_FALSE to stop
+    // Here's a more readable form:
+    // PRBool PR_CALLBACK enumerate(T* aElement, void* aData)
+    typedef PRBool (* PR_CALLBACK nsCOMArrayEnumFunc)
+        (T* aElement, void *aData);
     
+    // enumerate through the array with a callback. 
+    PRBool EnumerateForwards(nsCOMArrayEnumFunc aFunc, void* aData) {
+        return nsCOMArray_base::EnumerateForwards(nsVoidArrayEnumFunc(aFunc),
+                                                  aData);
+    }
+
+    // append an object, growing the array as necessary
     PRBool AppendObject(T *aObject) {
         return nsCOMArray_base::AppendObject(aObject);
     }
 
+    // remove the first instance of the given object and shrink the
+    // array as necessary
+    // Warning: if you pass null here, it will remove the first null element
     PRBool RemoveObject(T *aObject) {
         return nsCOMArray_base::RemoveObject(aObject);
     }
-    
+
+    // remove an element at a specific position, shrinking the array
+    // as necessary
     PRBool RemoveObjectAt(PRInt32 aIndex) {
         return nsCOMArray_base::RemoveObjectAt(aIndex);
     }
 
-
  private:
 
     // don't implement these!