pjs/layout/style/nsCSSDataBlock.cpp

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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is nsCSSDataBlock.cpp.
*
* The Initial Developer of the Original Code is L. David Baron.
* Portions created by the Initial Developer are Copyright (C) 2003
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* L. David Baron <dbaron@dbaron.org> (original author)
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
/*
* compact representation of the property-value pairs within a CSS
* declaration, and the code for expanding and compacting it
*/
#include "nsCSSDataBlock.h"
#include "mozilla/css/Declaration.h"
#include "nsRuleData.h"
#include "nsStyleSet.h"
#include "nsStyleContext.h"
namespace css = mozilla::css;
/*
* nsCSSCompressedDataBlock holds property-value pairs corresponding
* to CSS declaration blocks. Each pair is stored in a CDBValueStorage
* object; these objects form an array at the end of the data block.
*/
struct CDBValueStorage {
nsCSSProperty property;
nsCSSValue value;
};
enum {
CDBValueStorage_advance = sizeof(CDBValueStorage)
};
/*
* Define a bunch of utility functions for getting the property or any
* of the value types when the cursor is at the beginning of the storage
* for the property-value pair. The versions taking a non-const cursor
* argument return a reference so that the caller can assign into the
* result.
*/
inline nsCSSProperty& PropertyAtCursor(char *aCursor) {
return *reinterpret_cast<nsCSSProperty*>(aCursor);
}
inline nsCSSProperty PropertyAtCursor(const char *aCursor) {
return *reinterpret_cast<const nsCSSProperty*>(aCursor);
}
inline nsCSSValue* ValueAtCursor(char *aCursor) {
return & reinterpret_cast<CDBValueStorage*>(aCursor)->value;
}
inline const nsCSSValue* ValueAtCursor(const char *aCursor) {
return & reinterpret_cast<const CDBValueStorage*>(aCursor)->value;
}
/**
* Does a fast move of aSource to aDest. The previous value in
* aDest is cleanly destroyed, and aSource is cleared. Returns
* true if, before the copy, the value at aSource compared unequal
* to the value at aDest; false otherwise.
*/
static PRBool
MoveValue(nsCSSValue* aSource, nsCSSValue* aDest)
{
PRBool changed = (*aSource != *aDest);
aDest->~nsCSSValue();
memcpy(aDest, aSource, sizeof(nsCSSValue));
new (aSource) nsCSSValue();
return changed;
}
static PRBool
ShouldIgnoreColors(nsRuleData *aRuleData)
{
return aRuleData->mLevel != nsStyleSet::eAgentSheet &&
aRuleData->mLevel != nsStyleSet::eUserSheet &&
!aRuleData->mPresContext->UseDocumentColors();
}
/**
* Tries to call |nsCSSValue::StartImageLoad()| on an image source.
* Image sources are specified by |url()| or |-moz-image-rect()| function.
*/
static void
TryToStartImageLoadOnValue(const nsCSSValue& aValue, nsIDocument* aDocument)
{
if (aValue.GetUnit() == eCSSUnit_URL) {
aValue.StartImageLoad(aDocument);
}
else if (aValue.EqualsFunction(eCSSKeyword__moz_image_rect)) {
nsCSSValue::Array* arguments = aValue.GetArrayValue();
NS_ABORT_IF_FALSE(arguments->Count() == 6, "unexpected num of arguments");
const nsCSSValue& image = arguments->Item(1);
if (image.GetUnit() == eCSSUnit_URL)
image.StartImageLoad(aDocument);
}
}
static void
TryToStartImageLoad(const nsCSSValue& aValue, nsIDocument* aDocument,
nsCSSProperty aProperty)
{
if (aValue.GetUnit() == eCSSUnit_List) {
for (const nsCSSValueList* l = aValue.GetListValue(); l; l = l->mNext) {
TryToStartImageLoad(l->mValue, aDocument, aProperty);
}
} else if (nsCSSProps::PropHasFlags(aProperty,
CSS_PROPERTY_IMAGE_IS_IN_ARRAY_0)) {
if (aValue.GetUnit() == eCSSUnit_Array) {
TryToStartImageLoadOnValue(aValue.GetArrayValue()->Item(0), aDocument);
}
} else {
TryToStartImageLoadOnValue(aValue, aDocument);
}
}
static inline PRBool
ShouldStartImageLoads(nsRuleData *aRuleData, nsCSSProperty aProperty)
{
// Don't initiate image loads for if-visited styles. This is
// important because:
// (1) it's a waste of CPU and bandwidth
// (2) in some cases we'd start the image load on a style change
// where we wouldn't have started the load initially, which makes
// which links are visited detectable to Web pages (see bug
// 557287)
return !aRuleData->mStyleContext->IsStyleIfVisited() &&
nsCSSProps::PropHasFlags(aProperty, CSS_PROPERTY_START_IMAGE_LOADS);
}
void
nsCSSCompressedDataBlock::MapRuleInfoInto(nsRuleData *aRuleData) const
{
// If we have no data for these structs, then return immediately.
// This optimization should make us return most of the time, so we
// have to worry much less (although still some) about the speed of
// the rest of the function.
if (!(aRuleData->mSIDs & mStyleBits))
return;
nsIDocument* doc = aRuleData->mPresContext->Document();
const char* cursor = Block();
const char* cursor_end = BlockEnd();
while (cursor < cursor_end) {
nsCSSProperty iProp = PropertyAtCursor(cursor);
NS_ABORT_IF_FALSE(!nsCSSProps::IsShorthand(iProp), "out of range");
if (nsCachedStyleData::GetBitForSID(nsCSSProps::kSIDTable[iProp]) &
aRuleData->mSIDs) {
nsCSSValue* target = aRuleData->ValueFor(iProp);
if (target->GetUnit() == eCSSUnit_Null) {
const nsCSSValue *val = ValueAtCursor(cursor);
NS_ABORT_IF_FALSE(val->GetUnit() != eCSSUnit_Null, "oops");
if (ShouldStartImageLoads(aRuleData, iProp)) {
TryToStartImageLoad(*val, doc, iProp);
}
*target = *val;
if (nsCSSProps::PropHasFlags(iProp,
CSS_PROPERTY_IGNORED_WHEN_COLORS_DISABLED) &&
ShouldIgnoreColors(aRuleData))
{
if (iProp == eCSSProperty_background_color) {
// Force non-'transparent' background
// colors to the user's default.
if (target->IsNonTransparentColor()) {
target->SetColorValue(aRuleData->mPresContext->
DefaultBackgroundColor());
}
} else {
// Ignore 'color', 'border-*-color', etc.
*target = nsCSSValue();
}
}
}
}
cursor += CDBValueStorage_advance;
}
NS_ABORT_IF_FALSE(cursor == cursor_end, "inconsistent data");
}
const nsCSSValue*
nsCSSCompressedDataBlock::ValueFor(nsCSSProperty aProperty) const
{
NS_ABORT_IF_FALSE(!nsCSSProps::IsShorthand(aProperty),
"Don't call for shorthands");
// If we have no data for this struct, then return immediately.
// This optimization should make us return most of the time, so we
// have to worry much less (although still some) about the speed of
// the rest of the function.
if (!(nsCachedStyleData::GetBitForSID(nsCSSProps::kSIDTable[aProperty]) &
mStyleBits))
return nsnull;
const char* cursor = Block();
const char* cursor_end = BlockEnd();
while (cursor < cursor_end) {
nsCSSProperty iProp = PropertyAtCursor(cursor);
NS_ABORT_IF_FALSE(!nsCSSProps::IsShorthand(iProp), "out of range");
if (iProp == aProperty) {
return ValueAtCursor(cursor);
}
cursor += CDBValueStorage_advance;
}
NS_ABORT_IF_FALSE(cursor == cursor_end, "inconsistent data");
return nsnull;
}
PRBool
nsCSSCompressedDataBlock::TryReplaceValue(nsCSSProperty aProperty,
nsCSSExpandedDataBlock& aFromBlock,
PRBool *aChanged)
{
nsCSSValue* newValue = aFromBlock.PropertyAt(aProperty);
NS_ABORT_IF_FALSE(newValue && newValue->GetUnit() != eCSSUnit_Null,
"cannot replace with empty value");
const nsCSSValue* oldValue = ValueFor(aProperty);
if (!oldValue) {
*aChanged = PR_FALSE;
return PR_FALSE;
}
*aChanged = MoveValue(newValue, const_cast<nsCSSValue*>(oldValue));
aFromBlock.ClearPropertyBit(aProperty);
return PR_TRUE;
}
nsCSSCompressedDataBlock*
nsCSSCompressedDataBlock::Clone() const
{
const char *cursor = Block(), *cursor_end = BlockEnd();
char *result_cursor;
nsAutoPtr<nsCSSCompressedDataBlock> result
(new(cursor_end - cursor) nsCSSCompressedDataBlock());
if (!result)
return nsnull;
result_cursor = result->Block();
while (cursor < cursor_end) {
nsCSSProperty iProp = PropertyAtCursor(cursor);
NS_ABORT_IF_FALSE(!nsCSSProps::IsShorthand(iProp), "out of range");
PropertyAtCursor(result_cursor) = iProp;
const nsCSSValue* val = ValueAtCursor(cursor);
nsCSSValue *result_val = ValueAtCursor(result_cursor);
new (result_val) nsCSSValue(*val);
cursor += CDBValueStorage_advance;
result_cursor += CDBValueStorage_advance;
}
NS_ABORT_IF_FALSE(cursor == cursor_end, "inconsistent data");
result->mBlockEnd = result_cursor;
result->mStyleBits = mStyleBits;
NS_ABORT_IF_FALSE(result->DataSize() == DataSize(), "wrong size");
return result.forget();
}
nsCSSCompressedDataBlock::~nsCSSCompressedDataBlock()
{
const char* cursor = Block();
const char* cursor_end = BlockEnd();
while (cursor < cursor_end) {
nsCSSProperty iProp = PropertyAtCursor(cursor);
NS_ABORT_IF_FALSE(!nsCSSProps::IsShorthand(iProp), "out of range");
const nsCSSValue* val = ValueAtCursor(cursor);
NS_ABORT_IF_FALSE(val->GetUnit() != eCSSUnit_Null, "oops");
val->~nsCSSValue();
cursor += CDBValueStorage_advance;
}
NS_ABORT_IF_FALSE(cursor == cursor_end, "inconsistent data");
}
/* static */ nsCSSCompressedDataBlock*
nsCSSCompressedDataBlock::CreateEmptyBlock()
{
nsCSSCompressedDataBlock *result = new(0) nsCSSCompressedDataBlock();
result->mBlockEnd = result->Block();
return result;
}
/*****************************************************************************/
nsCSSExpandedDataBlock::nsCSSExpandedDataBlock()
{
AssertInitialState();
}
nsCSSExpandedDataBlock::~nsCSSExpandedDataBlock()
{
AssertInitialState();
}
void
nsCSSExpandedDataBlock::DoExpand(nsCSSCompressedDataBlock *aBlock,
PRBool aImportant)
{
/*
* Save needless copying and allocation by copying the memory
* corresponding to the stored data in the compressed block.
*/
const char* cursor = aBlock->Block();
const char* cursor_end = aBlock->BlockEnd();
while (cursor < cursor_end) {
nsCSSProperty iProp = PropertyAtCursor(cursor);
NS_ABORT_IF_FALSE(!nsCSSProps::IsShorthand(iProp), "out of range");
NS_ABORT_IF_FALSE(!HasPropertyBit(iProp),
"compressed block has property multiple times");
SetPropertyBit(iProp);
if (aImportant)
SetImportantBit(iProp);
const nsCSSValue* val = ValueAtCursor(cursor);
nsCSSValue* dest = PropertyAt(iProp);
NS_ABORT_IF_FALSE(val->GetUnit() != eCSSUnit_Null, "oops");
NS_ABORT_IF_FALSE(dest->GetUnit() == eCSSUnit_Null,
"expanding into non-empty block");
#ifdef NS_BUILD_REFCNT_LOGGING
dest->~nsCSSValue();
#endif
memcpy(dest, val, sizeof(nsCSSValue));
cursor += CDBValueStorage_advance;
}
NS_ABORT_IF_FALSE(cursor == cursor_end, "inconsistent data");
// Don't destroy remnants of what we just copied
aBlock->mBlockEnd = aBlock->Block();
delete aBlock;
}
void
nsCSSExpandedDataBlock::Expand(nsCSSCompressedDataBlock *aNormalBlock,
nsCSSCompressedDataBlock *aImportantBlock)
{
NS_ABORT_IF_FALSE(aNormalBlock, "unexpected null block");
AssertInitialState();
DoExpand(aNormalBlock, PR_FALSE);
if (aImportantBlock) {
DoExpand(aImportantBlock, PR_TRUE);
}
}
nsCSSExpandedDataBlock::ComputeSizeResult
nsCSSExpandedDataBlock::ComputeSize()
{
ComputeSizeResult result = {0, 0};
for (size_t iHigh = 0; iHigh < nsCSSPropertySet::kChunkCount; ++iHigh) {
if (!mPropertiesSet.HasPropertyInChunk(iHigh))
continue;
for (size_t iLow = 0; iLow < nsCSSPropertySet::kBitsInChunk; ++iLow) {
if (!mPropertiesSet.HasPropertyAt(iHigh, iLow))
continue;
nsCSSProperty iProp = nsCSSPropertySet::CSSPropertyAt(iHigh, iLow);
NS_ABORT_IF_FALSE(!nsCSSProps::IsShorthand(iProp), "out of range");
NS_ABORT_IF_FALSE(PropertyAt(iProp)->GetUnit() != eCSSUnit_Null,
"null value while computing size");
if (mPropertiesImportant.HasPropertyAt(iHigh, iLow))
result.important += CDBValueStorage_advance;
else
result.normal += CDBValueStorage_advance;
}
}
return result;
}
void
nsCSSExpandedDataBlock::Compress(nsCSSCompressedDataBlock **aNormalBlock,
nsCSSCompressedDataBlock **aImportantBlock)
{
nsAutoPtr<nsCSSCompressedDataBlock> result_normal, result_important;
char *cursor_normal, *cursor_important;
ComputeSizeResult size = ComputeSize();
result_normal = new(size.normal) nsCSSCompressedDataBlock();
cursor_normal = result_normal->Block();
if (size.important != 0) {
result_important = new(size.important) nsCSSCompressedDataBlock();
cursor_important = result_important->Block();
} else {
result_important = nsnull;
cursor_important = nsnull;
}
/*
* Save needless copying and allocation by copying the memory
* corresponding to the stored data in the expanded block, and then
* clearing the data in the expanded block.
*/
for (size_t iHigh = 0; iHigh < nsCSSPropertySet::kChunkCount; ++iHigh) {
if (!mPropertiesSet.HasPropertyInChunk(iHigh))
continue;
for (size_t iLow = 0; iLow < nsCSSPropertySet::kBitsInChunk; ++iLow) {
if (!mPropertiesSet.HasPropertyAt(iHigh, iLow))
continue;
nsCSSProperty iProp = nsCSSPropertySet::CSSPropertyAt(iHigh, iLow);
NS_ABORT_IF_FALSE(!nsCSSProps::IsShorthand(iProp), "out of range");
PRBool important =
mPropertiesImportant.HasPropertyAt(iHigh, iLow);
char *&cursor = important ? cursor_important : cursor_normal;
nsCSSCompressedDataBlock *result =
important ? result_important : result_normal;
nsCSSValue* val = PropertyAt(iProp);
NS_ABORT_IF_FALSE(val->GetUnit() != eCSSUnit_Null,
"Null value while compressing");
CDBValueStorage *storage =
reinterpret_cast<CDBValueStorage*>(cursor);
storage->property = iProp;
memcpy(&storage->value, val, sizeof(nsCSSValue));
new (val) nsCSSValue();
cursor += CDBValueStorage_advance;
result->mStyleBits |=
nsCachedStyleData::GetBitForSID(nsCSSProps::kSIDTable[iProp]);
}
}
result_normal->mBlockEnd = cursor_normal;
NS_ABORT_IF_FALSE(result_normal->DataSize() == ptrdiff_t(size.normal),
"size miscalculation");
if (result_important) {
result_important->mBlockEnd = cursor_important;
NS_ABORT_IF_FALSE(result_important->DataSize() ==
ptrdiff_t(size.important),
"size miscalculation");
}
ClearSets();
AssertInitialState();
*aNormalBlock = result_normal.forget();
*aImportantBlock = result_important.forget();
}
void
nsCSSExpandedDataBlock::AddLonghandProperty(nsCSSProperty aProperty,
const nsCSSValue& aValue)
{
NS_ABORT_IF_FALSE(!nsCSSProps::IsShorthand(aProperty),
"property out of range");
nsCSSValue& storage = *static_cast<nsCSSValue*>(PropertyAt(aProperty));
storage = aValue;
SetPropertyBit(aProperty);
}
void
nsCSSExpandedDataBlock::Clear()
{
for (size_t iHigh = 0; iHigh < nsCSSPropertySet::kChunkCount; ++iHigh) {
if (!mPropertiesSet.HasPropertyInChunk(iHigh))
continue;
for (size_t iLow = 0; iLow < nsCSSPropertySet::kBitsInChunk; ++iLow) {
if (!mPropertiesSet.HasPropertyAt(iHigh, iLow))
continue;
nsCSSProperty iProp = nsCSSPropertySet::CSSPropertyAt(iHigh, iLow);
ClearLonghandProperty(iProp);
}
}
AssertInitialState();
}
void
nsCSSExpandedDataBlock::ClearProperty(nsCSSProperty aPropID)
{
if (nsCSSProps::IsShorthand(aPropID)) {
CSSPROPS_FOR_SHORTHAND_SUBPROPERTIES(p, aPropID) {
ClearLonghandProperty(*p);
}
} else {
ClearLonghandProperty(aPropID);
}
}
void
nsCSSExpandedDataBlock::ClearLonghandProperty(nsCSSProperty aPropID)
{
NS_ABORT_IF_FALSE(!nsCSSProps::IsShorthand(aPropID), "out of range");
ClearPropertyBit(aPropID);
ClearImportantBit(aPropID);
PropertyAt(aPropID)->Reset();
}
PRBool
nsCSSExpandedDataBlock::TransferFromBlock(nsCSSExpandedDataBlock& aFromBlock,
nsCSSProperty aPropID,
PRBool aIsImportant,
PRBool aOverrideImportant,
PRBool aMustCallValueAppended,
css::Declaration* aDeclaration)
{
if (!nsCSSProps::IsShorthand(aPropID)) {
return DoTransferFromBlock(aFromBlock, aPropID,
aIsImportant, aOverrideImportant,
aMustCallValueAppended, aDeclaration);
}
PRBool changed = PR_FALSE;
CSSPROPS_FOR_SHORTHAND_SUBPROPERTIES(p, aPropID) {
changed |= DoTransferFromBlock(aFromBlock, *p,
aIsImportant, aOverrideImportant,
aMustCallValueAppended, aDeclaration);
}
return changed;
}
PRBool
nsCSSExpandedDataBlock::DoTransferFromBlock(nsCSSExpandedDataBlock& aFromBlock,
nsCSSProperty aPropID,
PRBool aIsImportant,
PRBool aOverrideImportant,
PRBool aMustCallValueAppended,
css::Declaration* aDeclaration)
{
PRBool changed = PR_FALSE;
NS_ABORT_IF_FALSE(aFromBlock.HasPropertyBit(aPropID), "oops");
if (aIsImportant) {
if (!HasImportantBit(aPropID))
changed = PR_TRUE;
SetImportantBit(aPropID);
} else {
if (HasImportantBit(aPropID)) {
// When parsing a declaration block, an !important declaration
// is not overwritten by an ordinary declaration of the same
// property later in the block. However, CSSOM manipulations
// come through here too, and in that case we do want to
// overwrite the property.
if (!aOverrideImportant) {
aFromBlock.ClearLonghandProperty(aPropID);
return PR_FALSE;
}
changed = PR_TRUE;
ClearImportantBit(aPropID);
}
}
if (aMustCallValueAppended || !HasPropertyBit(aPropID)) {
aDeclaration->ValueAppended(aPropID);
}
SetPropertyBit(aPropID);
aFromBlock.ClearPropertyBit(aPropID);
/*
* Save needless copying and allocation by calling the destructor in
* the destination, copying memory directly, and then using placement
* new.
*/
changed |= MoveValue(aFromBlock.PropertyAt(aPropID), PropertyAt(aPropID));
return changed;
}
#ifdef DEBUG
void
nsCSSExpandedDataBlock::DoAssertInitialState()
{
mPropertiesSet.AssertIsEmpty("not initial state");
mPropertiesImportant.AssertIsEmpty("not initial state");
for (PRUint32 i = 0; i < eCSSProperty_COUNT_no_shorthands; ++i) {
nsCSSProperty prop = nsCSSProperty(i);
NS_ABORT_IF_FALSE(PropertyAt(prop)->GetUnit() == eCSSUnit_Null,
"not initial state");
}
}
#endif