gecko-dev/layout/base/nsChildIterator.h

162 строки
4.4 KiB
C++

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
// vim:cindent:ts=2:et:sw=2:
/* 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/. */
/*
* 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:
nsIContent* mContent;
// If mNodes is non-null (so XBLInvolved() is true), mIndex is the
// index into mNodes for our current position. Otherwise, mChild is
// our current child (which might be null if we're done iterating).
union {
uint32_t mIndex;
nsIContent* mChild;
};
nsINodeList* mNodes;
public:
ChildIterator()
: mContent(nullptr), mChild(0), mNodes(nullptr) {}
ChildIterator(const ChildIterator& aOther)
: mContent(aOther.mContent),
mNodes(aOther.mNodes) {
if (XBLInvolved()) {
mIndex = aOther.mIndex;
} else {
mChild = aOther.mChild;
}
}
ChildIterator& operator=(const ChildIterator& aOther) {
mContent = aOther.mContent;
mNodes = aOther.mNodes;
if (XBLInvolved()) {
mIndex = aOther.mIndex;
} else {
mChild = aOther.mChild;
}
return *this;
}
ChildIterator& operator++() {
if (XBLInvolved()) {
++mIndex;
} else {
NS_ASSERTION(mChild, "Walking off end of list?");
mChild = mChild->GetNextSibling();
}
return *this;
}
ChildIterator operator++(int) {
ChildIterator result(*this);
++(*this);
return result;
}
ChildIterator& operator--() {
if (XBLInvolved()) {
--mIndex;
} else if (mChild) {
mChild = mChild->GetPreviousSibling();
NS_ASSERTION(mChild, "Walking off beginning of list");
} else {
mChild = mContent->GetLastChild();
}
return *this;
}
ChildIterator operator--(int) {
ChildIterator result(*this);
--(*this);
return result;
}
nsIContent* get() const {
if (XBLInvolved()) {
return mNodes->Item(mIndex);
}
return mChild;
}
nsIContent* operator*() const { return get(); }
bool operator==(const ChildIterator& aOther) const {
if (XBLInvolved()) {
return mContent == aOther.mContent && mIndex == aOther.mIndex;
}
return mContent == aOther.mContent && mChild == aOther.mChild;
}
bool operator!=(const ChildIterator& aOther) const {
return !aOther.operator==(*this);
}
void seek(nsIContent* aContent) {
if (XBLInvolved()) {
int32_t index = mNodes->IndexOf(aContent);
// XXXbz I wish we could assert that index != -1, but it 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();
}
} else if (aContent->GetParent() == mContent) {
mChild = aContent;
} else {
// XXXbz I wish we could assert this doesn't happen, but I think that's
// not necessarily the case when called from ContentInserted if
// first-letter frames are about.
mChild = nullptr;
}
}
bool XBLInvolved() const { return mNodes != nullptr; }
/**
* 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:
uint32_t length() {
NS_PRECONDITION(XBLInvolved(), "Don't call me");
uint32_t l;
mNodes->GetLength(&l);
return l;
}
};