gecko-dev/layout/base/nsChildIterator.h

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
// vim:cindent:ts=2:et:sw=2:
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/*
* used by nsCSSFrameConstructor to determine and iterate the child list
* used to construct frames (normal children or something from XBL)
*/
#include "nsCOMPtr.h"
#include "nsIContent.h"
#include "nsINodeList.h"
/**
* Helper class for iterating children during frame construction.
* This class should always be used in lieu of the straight content
* node APIs, since it handles XBL-generated anonymous content as
* well.
*/
class NS_STACK_CLASS ChildIterator
{
protected:
// We could just use a mNodes for the case when we're not dealing with XBL
// anon content too, but in practice that would basically replace our current
// branch on mNodes with an extra virtual function call in the common case.
nsIContent* mContent;
PRUint32 mIndex;
nsINodeList* mNodes;
public:
ChildIterator()
: mContent(nsnull), mIndex(0), mNodes(nsnull) {}
ChildIterator(const ChildIterator& aOther)
: mContent(aOther.mContent),
mIndex(aOther.mIndex),
mNodes(aOther.mNodes) {}
ChildIterator& operator=(const ChildIterator& aOther) {
mContent = aOther.mContent;
mIndex = aOther.mIndex;
mNodes = aOther.mNodes;
return *this;
}
ChildIterator& operator++() {
++mIndex;
return *this;
}
ChildIterator operator++(int) {
ChildIterator result(*this);
++mIndex;
return result;
}
ChildIterator& operator--() {
--mIndex;
return *this;
}
ChildIterator operator--(int) {
ChildIterator result(*this);
--mIndex;
return result;
}
nsIContent* get() const {
if (XBLInvolved()) {
return mNodes->GetNodeAt(mIndex);
}
return mContent->GetChildAt(mIndex);
}
nsIContent* operator*() const { return get(); }
PRBool operator==(const ChildIterator& aOther) const {
return mContent == aOther.mContent && mIndex == aOther.mIndex;
}
PRBool operator!=(const ChildIterator& aOther) const {
return !aOther.operator==(*this);
}
PRUint32 position() {
return mIndex;
}
void seek(PRUint32 aIndex) {
// Make sure that aIndex is reasonable. This should be |#ifdef
// DEBUG|, but we need these numbers for the temporary workaround
// for bug 133219.
PRUint32 l = length();
NS_ASSERTION(PRInt32(aIndex) >= 0 && aIndex <= l, "out of bounds");
// Temporary workaround for bug 133219.
if (aIndex > l)
aIndex = l;
mIndex = aIndex;
}
void seek(nsIContent* aContent) {
PRInt32 index;
if (XBLInvolved()) {
index = mNodes->IndexOf(aContent);
} else {
index = mContent->IndexOf(aContent);
}
// XXXbz I wish we could assert that index != -1, but I think that's not
// necessarily the case when called from ContentInserted if first-letter
// frames are about. It also seems to not be the case in some XBL cases
// with filtered insertion points and no default insertion point. I will
// now claim that XBL's management of its insertion points is broken in
// those cases, since it's returning an insertion parent for a node that
// doesn't actually have the node in its child list according to
// ChildIterator. See bug 474324.
if (index != -1) {
mIndex = index;
} else {
// If aContent isn't going to get hit by this iterator, just seek to the
// end of the list for lack of anything better to do.
mIndex = length();
}
}
PRBool XBLInvolved() const { return mNodes != nsnull; }
/**
* Create a pair of ChildIterators for a content node. aFirst will
* point to the first child of aContent; aLast will point one past
* the last child of aContent.
*/
static nsresult Init(nsIContent* aContent,
ChildIterator* aFirst,
ChildIterator* aLast);
private:
PRUint32 length() {
PRUint32 l;
if (XBLInvolved()) {
mNodes->GetLength(&l);
} else {
l = mContent->GetChildCount();
}
return l;
}
};