зеркало из https://github.com/mozilla/gecko-dev.git
328 строки
11 KiB
C++
328 строки
11 KiB
C++
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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/* ***** BEGIN LICENSE BLOCK *****
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* Version: MPL 1.1/GPL 2.0/LGPL 2.1
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*
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* The contents of this file are subject to the Mozilla Public License Version
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* 1.1 (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* Software distributed under the License is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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* for the specific language governing rights and limitations under the
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* License.
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*
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* The Original Code is nsCSSDataBlock.h.
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*
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* The Initial Developer of the Original Code is L. David Baron.
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* Portions created by the Initial Developer are Copyright (C) 2003
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* the Initial Developer. All Rights Reserved.
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*
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* Contributor(s):
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* L. David Baron <dbaron@dbaron.org> (original author)
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*
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* Alternatively, the contents of this file may be used under the terms of
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* either the GNU General Public License Version 2 or later (the "GPL"), or
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* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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* in which case the provisions of the GPL or the LGPL are applicable instead
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* of those above. If you wish to allow use of your version of this file only
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* under the terms of either the GPL or the LGPL, and not to allow others to
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* use your version of this file under the terms of the MPL, indicate your
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* decision by deleting the provisions above and replace them with the notice
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* and other provisions required by the GPL or the LGPL. If you do not delete
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* the provisions above, a recipient may use your version of this file under
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* the terms of any one of the MPL, the GPL or the LGPL.
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*
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* ***** END LICENSE BLOCK ***** */
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/*
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* compact representation of the property-value pairs within a CSS
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* declaration, and the code for expanding and compacting it
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*/
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#ifndef nsCSSDataBlock_h__
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#define nsCSSDataBlock_h__
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#include "nsCSSProps.h"
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#include "nsCSSPropertySet.h"
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struct nsRuleData;
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class nsCSSExpandedDataBlock;
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namespace mozilla {
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namespace css {
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class Declaration;
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}
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}
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/*
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* nsCSSCompressedDataBlock holds property-value pairs corresponding
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* to CSS declaration blocks. Each pair is stored in a CDBValueStorage
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* object; these objects form an array at the end of the data block.
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*/
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struct CDBValueStorage {
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nsCSSProperty property;
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nsCSSValue value;
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};
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/**
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* An |nsCSSCompressedDataBlock| holds a usually-immutable chunk of
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* property-value data for a CSS declaration block (which we misname a
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* |css::Declaration|). Mutation is accomplished through
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* |nsCSSExpandedDataBlock| or in some cases via direct slot access.
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*/
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class nsCSSCompressedDataBlock {
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private:
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friend class nsCSSExpandedDataBlock;
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// Only this class (via |CreateEmptyBlock|) or nsCSSExpandedDataBlock
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// (in |Compress|) can create compressed data blocks.
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nsCSSCompressedDataBlock() : mStyleBits(0) {}
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public:
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~nsCSSCompressedDataBlock();
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/**
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* Do what |nsIStyleRule::MapRuleInfoInto| needs to do for a style
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* rule using this block for storage.
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*/
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void MapRuleInfoInto(nsRuleData *aRuleData) const;
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/**
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* Return the location at which the *value* for the property is
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* stored, or null if the block does not contain a value for the
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* property.
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*
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* Inefficient (by design).
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*
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* Must not be called for shorthands.
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*/
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const nsCSSValue* ValueFor(nsCSSProperty aProperty) const;
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/**
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* Attempt to replace the value for |aProperty| stored in this block
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* with the matching value stored in |aFromBlock|.
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* This method will fail (returning false) if |aProperty| is not
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* already in this block. It will set |aChanged| to true if it
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* actually made a change to the block, but regardless, if it
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* returns true, the value in |aFromBlock| was erased.
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*/
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bool TryReplaceValue(nsCSSProperty aProperty,
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nsCSSExpandedDataBlock& aFromBlock,
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bool* aChanged);
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/**
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* Clone this block, or return null on out-of-memory.
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*/
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nsCSSCompressedDataBlock* Clone() const;
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/**
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* Create a new nsCSSCompressedDataBlock holding no declarations.
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*/
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static nsCSSCompressedDataBlock* CreateEmptyBlock();
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private:
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void* operator new(size_t aBaseSize, size_t aDataSize) {
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NS_ABORT_IF_FALSE(aBaseSize == sizeof(nsCSSCompressedDataBlock),
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"unexpected size for nsCSSCompressedDataBlock");
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return ::operator new(aBaseSize + aDataSize);
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}
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/**
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* Delete all the data stored in this block, and the block itself.
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*/
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void Destroy();
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PRInt32 mStyleBits; // the structs for which we have data, according to
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// |nsCachedStyleData::GetBitForSID|.
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PRUint32 mDataSize;
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// CDBValueStorage elements are stored after these fields. Space for them
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// is allocated in |operator new| above. The static assertions following
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// this class make sure that the CDBValueStorage elements are aligned
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// appropriately.
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char* Block() { return (char*)this + sizeof(*this); }
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char* BlockEnd() { return Block() + mDataSize; }
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const char* Block() const { return (char*)this + sizeof(*this); }
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const char* BlockEnd() const { return Block() + mDataSize; }
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void SetBlockEnd(char *blockEnd) {
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/*
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* Note: if we ever change nsCSSDeclaration to store the declarations
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* in order and also store repeated declarations of the same property,
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* then we need to worry about checking for integer overflow here.
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*/
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NS_ABORT_IF_FALSE(size_t(blockEnd - Block()) <= size_t(PR_UINT32_MAX),
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"overflow of mDataSize");
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mDataSize = PRUint32(blockEnd - Block());
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}
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ptrdiff_t DataSize() const { return mDataSize; }
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};
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/* Make sure the CDBValueStorage elements are aligned appropriately. */
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PR_STATIC_ASSERT(sizeof(nsCSSCompressedDataBlock) == 8);
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PR_STATIC_ASSERT(NS_ALIGNMENT_OF(CDBValueStorage) <= 8);
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class nsCSSExpandedDataBlock {
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friend class nsCSSCompressedDataBlock;
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public:
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nsCSSExpandedDataBlock();
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~nsCSSExpandedDataBlock();
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private:
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/* Property storage may not be accessed directly; use AddLonghandProperty
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* and friends.
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*/
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nsCSSValue mValues[eCSSProperty_COUNT_no_shorthands];
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public:
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/**
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* Transfer all of the state from a pair of compressed data blocks
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* to this expanded block. This expanded block must be clear
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* beforehand.
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*
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* This method DELETES both of the compressed data blocks it is
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* passed. (This is necessary because ownership of sub-objects
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* is transferred to the expanded block.)
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*/
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void Expand(nsCSSCompressedDataBlock *aNormalBlock,
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nsCSSCompressedDataBlock *aImportantBlock);
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/**
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* Allocate new compressed blocks and transfer all of the state
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* from this expanded block to the new blocks, clearing this
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* expanded block. A normal block will always be allocated, but
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* an important block will only be allocated if there are
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* !important properties in the expanded block; otherwise
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* |*aImportantBlock| will be set to null.
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*/
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void Compress(nsCSSCompressedDataBlock **aNormalBlock,
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nsCSSCompressedDataBlock **aImportantBlock);
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/**
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* Copy a value into this expanded block. This does NOT destroy
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* the source value object. |aProperty| cannot be a shorthand.
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*/
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void AddLonghandProperty(nsCSSProperty aProperty, const nsCSSValue& aValue);
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/**
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* Clear the state of this expanded block.
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*/
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void Clear();
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/**
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* Clear the data for the given property (including the set and
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* important bits). Can be used with shorthand properties.
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*/
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void ClearProperty(nsCSSProperty aPropID);
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/**
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* Same as ClearProperty, but faster and cannot be used with shorthands.
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*/
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void ClearLonghandProperty(nsCSSProperty aPropID);
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/**
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* Transfer the state for |aPropID| (which may be a shorthand)
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* from |aFromBlock| to this block. The property being transferred
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* is !important if |aIsImportant| is true, and should replace an
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* existing !important property regardless of its own importance
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* if |aOverrideImportant| is true.
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*
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* Returns true if something changed, false otherwise. Calls
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* |ValueAppended| on |aDeclaration| if the property was not
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* previously set, or in any case if |aMustCallValueAppended| is true.
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*/
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bool TransferFromBlock(nsCSSExpandedDataBlock& aFromBlock,
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nsCSSProperty aPropID,
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bool aIsImportant,
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bool aOverrideImportant,
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bool aMustCallValueAppended,
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mozilla::css::Declaration* aDeclaration);
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void AssertInitialState() {
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#ifdef DEBUG
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DoAssertInitialState();
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#endif
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}
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private:
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/**
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* Compute the size that will be occupied by the result of
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* |Compress|.
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*/
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struct ComputeSizeResult {
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PRUint32 normal, important;
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};
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ComputeSizeResult ComputeSize();
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void DoExpand(nsCSSCompressedDataBlock *aBlock, bool aImportant);
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/**
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* Worker for TransferFromBlock; cannot be used with shorthands.
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*/
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bool DoTransferFromBlock(nsCSSExpandedDataBlock& aFromBlock,
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nsCSSProperty aPropID,
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bool aIsImportant,
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bool aOverrideImportant,
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bool aMustCallValueAppended,
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mozilla::css::Declaration* aDeclaration);
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#ifdef DEBUG
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void DoAssertInitialState();
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#endif
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/*
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* mPropertiesSet stores a bit for every property that is present,
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* to optimize compression of blocks with small numbers of
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* properties (the norm) and to allow quickly checking whether a
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* property is set in this block.
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*/
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nsCSSPropertySet mPropertiesSet;
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/*
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* mPropertiesImportant indicates which properties are '!important'.
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*/
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nsCSSPropertySet mPropertiesImportant;
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/*
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* Return the storage location within |this| of the value of the
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* property |aProperty|.
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*/
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nsCSSValue* PropertyAt(nsCSSProperty aProperty) {
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NS_ABORT_IF_FALSE(0 <= aProperty &&
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aProperty < eCSSProperty_COUNT_no_shorthands,
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"property out of range");
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return &mValues[aProperty];
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}
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void SetPropertyBit(nsCSSProperty aProperty) {
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mPropertiesSet.AddProperty(aProperty);
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}
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void ClearPropertyBit(nsCSSProperty aProperty) {
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mPropertiesSet.RemoveProperty(aProperty);
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}
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bool HasPropertyBit(nsCSSProperty aProperty) {
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return mPropertiesSet.HasProperty(aProperty);
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}
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void SetImportantBit(nsCSSProperty aProperty) {
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mPropertiesImportant.AddProperty(aProperty);
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}
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void ClearImportantBit(nsCSSProperty aProperty) {
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mPropertiesImportant.RemoveProperty(aProperty);
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}
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bool HasImportantBit(nsCSSProperty aProperty) {
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return mPropertiesImportant.HasProperty(aProperty);
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}
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void ClearSets() {
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mPropertiesSet.Empty();
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mPropertiesImportant.Empty();
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}
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};
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#endif /* !defined(nsCSSDataBlock_h__) */
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