1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/layout/style/nsCSSDataBlock.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,351 @@
1.4 +/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
1.5 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.6 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.7 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.8 +
1.9 +/*
1.10 + * compact representation of the property-value pairs within a CSS
1.11 + * declaration, and the code for expanding and compacting it
1.12 + */
1.13 +
1.14 +#ifndef nsCSSDataBlock_h__
1.15 +#define nsCSSDataBlock_h__
1.16 +
1.17 +#include "mozilla/MemoryReporting.h"
1.18 +#include "nsCSSProps.h"
1.19 +#include "nsCSSPropertySet.h"
1.20 +#include "nsCSSValue.h"
1.21 +#include "imgRequestProxy.h"
1.22 +
1.23 +struct nsRuleData;
1.24 +class nsCSSExpandedDataBlock;
1.25 +
1.26 +namespace mozilla {
1.27 +namespace css {
1.28 +class Declaration;
1.29 +}
1.30 +}
1.31 +
1.32 +/**
1.33 + * An |nsCSSCompressedDataBlock| holds a usually-immutable chunk of
1.34 + * property-value data for a CSS declaration block (which we misname a
1.35 + * |css::Declaration|). Mutation is accomplished through
1.36 + * |nsCSSExpandedDataBlock| or in some cases via direct slot access.
1.37 + */
1.38 +class nsCSSCompressedDataBlock {
1.39 +private:
1.40 + friend class nsCSSExpandedDataBlock;
1.41 +
1.42 + // Only this class (via |CreateEmptyBlock|) or nsCSSExpandedDataBlock
1.43 + // (in |Compress|) can create compressed data blocks.
1.44 + nsCSSCompressedDataBlock(uint32_t aNumProps)
1.45 + : mStyleBits(0), mNumProps(aNumProps)
1.46 + {}
1.47 +
1.48 +public:
1.49 + ~nsCSSCompressedDataBlock();
1.50 +
1.51 + /**
1.52 + * Do what |nsIStyleRule::MapRuleInfoInto| needs to do for a style
1.53 + * rule using this block for storage.
1.54 + */
1.55 + void MapRuleInfoInto(nsRuleData *aRuleData) const;
1.56 +
1.57 + /**
1.58 + * Return the location at which the *value* for the property is
1.59 + * stored, or null if the block does not contain a value for the
1.60 + * property.
1.61 + *
1.62 + * Inefficient (by design).
1.63 + *
1.64 + * Must not be called for shorthands.
1.65 + */
1.66 + const nsCSSValue* ValueFor(nsCSSProperty aProperty) const;
1.67 +
1.68 + /**
1.69 + * Attempt to replace the value for |aProperty| stored in this block
1.70 + * with the matching value stored in |aFromBlock|.
1.71 + * This method will fail (returning false) if |aProperty| is not
1.72 + * already in this block. It will set |aChanged| to true if it
1.73 + * actually made a change to the block, but regardless, if it
1.74 + * returns true, the value in |aFromBlock| was erased.
1.75 + */
1.76 + bool TryReplaceValue(nsCSSProperty aProperty,
1.77 + nsCSSExpandedDataBlock& aFromBlock,
1.78 + bool* aChanged);
1.79 +
1.80 + /**
1.81 + * Clone this block, or return null on out-of-memory.
1.82 + */
1.83 + nsCSSCompressedDataBlock* Clone() const;
1.84 +
1.85 + /**
1.86 + * Create a new nsCSSCompressedDataBlock holding no declarations.
1.87 + */
1.88 + static nsCSSCompressedDataBlock* CreateEmptyBlock();
1.89 +
1.90 + size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
1.91 +
1.92 + bool HasDefaultBorderImageSlice() const;
1.93 + bool HasDefaultBorderImageWidth() const;
1.94 + bool HasDefaultBorderImageOutset() const;
1.95 + bool HasDefaultBorderImageRepeat() const;
1.96 +
1.97 +private:
1.98 + void* operator new(size_t aBaseSize, uint32_t aNumProps) {
1.99 + NS_ABORT_IF_FALSE(aBaseSize == sizeof(nsCSSCompressedDataBlock),
1.100 + "unexpected size for nsCSSCompressedDataBlock");
1.101 + return ::operator new(aBaseSize + DataSize(aNumProps));
1.102 + }
1.103 +
1.104 +public:
1.105 + // Ideally, |nsCSSProperty| would be |enum nsCSSProperty : int16_t|. But
1.106 + // not all of the compilers we use are modern enough to support small
1.107 + // enums. So we manually squeeze nsCSSProperty into 16 bits ourselves.
1.108 + // The static assertion below ensures it fits.
1.109 + typedef int16_t CompressedCSSProperty;
1.110 + static const size_t MaxCompressedCSSProperty = INT16_MAX;
1.111 +
1.112 +private:
1.113 + static size_t DataSize(uint32_t aNumProps) {
1.114 + return size_t(aNumProps) *
1.115 + (sizeof(nsCSSValue) + sizeof(CompressedCSSProperty));
1.116 + }
1.117 +
1.118 + int32_t mStyleBits; // the structs for which we have data, according to
1.119 + // |nsCachedStyleData::GetBitForSID|.
1.120 + uint32_t mNumProps;
1.121 + // nsCSSValue elements are stored after these fields, and
1.122 + // nsCSSProperty elements are stored -- each one compressed as a
1.123 + // CompressedCSSProperty -- after the nsCSSValue elements. Space for them
1.124 + // is allocated in |operator new| above. The static assertions following
1.125 + // this class make sure that the value and property elements are aligned
1.126 + // appropriately.
1.127 +
1.128 + nsCSSValue* Values() const {
1.129 + return (nsCSSValue*)(this + 1);
1.130 + }
1.131 +
1.132 + CompressedCSSProperty* CompressedProperties() const {
1.133 + return (CompressedCSSProperty*)(Values() + mNumProps);
1.134 + }
1.135 +
1.136 + nsCSSValue* ValueAtIndex(uint32_t i) const {
1.137 + NS_ABORT_IF_FALSE(i < mNumProps, "value index out of range");
1.138 + return Values() + i;
1.139 + }
1.140 +
1.141 + nsCSSProperty PropertyAtIndex(uint32_t i) const {
1.142 + NS_ABORT_IF_FALSE(i < mNumProps, "property index out of range");
1.143 + nsCSSProperty prop = (nsCSSProperty)CompressedProperties()[i];
1.144 + NS_ABORT_IF_FALSE(!nsCSSProps::IsShorthand(prop), "out of range");
1.145 + return prop;
1.146 + }
1.147 +
1.148 + void CopyValueToIndex(uint32_t i, nsCSSValue* aValue) {
1.149 + new (ValueAtIndex(i)) nsCSSValue(*aValue);
1.150 + }
1.151 +
1.152 + void RawCopyValueToIndex(uint32_t i, nsCSSValue* aValue) {
1.153 + memcpy(ValueAtIndex(i), aValue, sizeof(nsCSSValue));
1.154 + }
1.155 +
1.156 + void SetPropertyAtIndex(uint32_t i, nsCSSProperty aProperty) {
1.157 + NS_ABORT_IF_FALSE(i < mNumProps, "set property index out of range");
1.158 + CompressedProperties()[i] = (CompressedCSSProperty)aProperty;
1.159 + }
1.160 +
1.161 + void SetNumPropsToZero() {
1.162 + mNumProps = 0;
1.163 + }
1.164 +};
1.165 +
1.166 +// Make sure the values and properties are aligned appropriately. (These
1.167 +// assertions are stronger than necessary to keep them simple.)
1.168 +static_assert(sizeof(nsCSSCompressedDataBlock) == 8,
1.169 + "nsCSSCompressedDataBlock's size has changed");
1.170 +static_assert(NS_ALIGNMENT_OF(nsCSSValue) == 4 || NS_ALIGNMENT_OF(nsCSSValue) == 8,
1.171 + "nsCSSValue doesn't align with nsCSSCompressedDataBlock");
1.172 +static_assert(NS_ALIGNMENT_OF(nsCSSCompressedDataBlock::CompressedCSSProperty) == 2,
1.173 + "CompressedCSSProperty doesn't align with nsCSSValue");
1.174 +
1.175 +// Make sure that sizeof(CompressedCSSProperty) is big enough.
1.176 +static_assert(eCSSProperty_COUNT_no_shorthands <=
1.177 + nsCSSCompressedDataBlock::MaxCompressedCSSProperty,
1.178 + "nsCSSProperty doesn't fit in StoredSizeOfCSSProperty");
1.179 +
1.180 +class nsCSSExpandedDataBlock {
1.181 + friend class nsCSSCompressedDataBlock;
1.182 +
1.183 +public:
1.184 + nsCSSExpandedDataBlock();
1.185 + ~nsCSSExpandedDataBlock();
1.186 +
1.187 +private:
1.188 + /* Property storage may not be accessed directly; use AddLonghandProperty
1.189 + * and friends.
1.190 + */
1.191 + nsCSSValue mValues[eCSSProperty_COUNT_no_shorthands];
1.192 +
1.193 +public:
1.194 + /**
1.195 + * Transfer all of the state from a pair of compressed data blocks
1.196 + * to this expanded block. This expanded block must be clear
1.197 + * beforehand.
1.198 + *
1.199 + * This method DELETES both of the compressed data blocks it is
1.200 + * passed. (This is necessary because ownership of sub-objects
1.201 + * is transferred to the expanded block.)
1.202 + */
1.203 + void Expand(nsCSSCompressedDataBlock *aNormalBlock,
1.204 + nsCSSCompressedDataBlock *aImportantBlock);
1.205 +
1.206 + /**
1.207 + * Allocate new compressed blocks and transfer all of the state
1.208 + * from this expanded block to the new blocks, clearing this
1.209 + * expanded block. A normal block will always be allocated, but
1.210 + * an important block will only be allocated if there are
1.211 + * !important properties in the expanded block; otherwise
1.212 + * |*aImportantBlock| will be set to null.
1.213 + */
1.214 + void Compress(nsCSSCompressedDataBlock **aNormalBlock,
1.215 + nsCSSCompressedDataBlock **aImportantBlock);
1.216 +
1.217 + /**
1.218 + * Copy a value into this expanded block. This does NOT destroy
1.219 + * the source value object. |aProperty| cannot be a shorthand.
1.220 + */
1.221 + void AddLonghandProperty(nsCSSProperty aProperty, const nsCSSValue& aValue);
1.222 +
1.223 + /**
1.224 + * Clear the state of this expanded block.
1.225 + */
1.226 + void Clear();
1.227 +
1.228 + /**
1.229 + * Clear the data for the given property (including the set and
1.230 + * important bits). Can be used with shorthand properties.
1.231 + */
1.232 + void ClearProperty(nsCSSProperty aPropID);
1.233 +
1.234 + /**
1.235 + * Same as ClearProperty, but faster and cannot be used with shorthands.
1.236 + */
1.237 + void ClearLonghandProperty(nsCSSProperty aPropID);
1.238 +
1.239 + /**
1.240 + * Transfer the state for |aPropID| (which may be a shorthand)
1.241 + * from |aFromBlock| to this block. The property being transferred
1.242 + * is !important if |aIsImportant| is true, and should replace an
1.243 + * existing !important property regardless of its own importance
1.244 + * if |aOverrideImportant| is true.
1.245 + *
1.246 + * Returns true if something changed, false otherwise. Calls
1.247 + * |ValueAppended| on |aDeclaration| if the property was not
1.248 + * previously set, or in any case if |aMustCallValueAppended| is true.
1.249 + */
1.250 + bool TransferFromBlock(nsCSSExpandedDataBlock& aFromBlock,
1.251 + nsCSSProperty aPropID,
1.252 + bool aIsImportant,
1.253 + bool aOverrideImportant,
1.254 + bool aMustCallValueAppended,
1.255 + mozilla::css::Declaration* aDeclaration);
1.256 +
1.257 + /**
1.258 + * Copies the values for aPropID into the specified aRuleData object.
1.259 + *
1.260 + * This is used for copying parsed-at-computed-value-time properties
1.261 + * that had variable references. aPropID must be a longhand property.
1.262 + */
1.263 + void MapRuleInfoInto(nsCSSProperty aPropID, nsRuleData* aRuleData) const;
1.264 +
1.265 + void AssertInitialState() {
1.266 +#ifdef DEBUG
1.267 + DoAssertInitialState();
1.268 +#endif
1.269 + }
1.270 +
1.271 +private:
1.272 + /**
1.273 + * Compute the number of properties that will be present in the
1.274 + * result of |Compress|.
1.275 + */
1.276 + void ComputeNumProps(uint32_t* aNumPropsNormal,
1.277 + uint32_t* aNumPropsImportant);
1.278 +
1.279 + void DoExpand(nsCSSCompressedDataBlock *aBlock, bool aImportant);
1.280 +
1.281 + /**
1.282 + * Worker for TransferFromBlock; cannot be used with shorthands.
1.283 + */
1.284 + bool DoTransferFromBlock(nsCSSExpandedDataBlock& aFromBlock,
1.285 + nsCSSProperty aPropID,
1.286 + bool aIsImportant,
1.287 + bool aOverrideImportant,
1.288 + bool aMustCallValueAppended,
1.289 + mozilla::css::Declaration* aDeclaration);
1.290 +
1.291 +#ifdef DEBUG
1.292 + void DoAssertInitialState();
1.293 +#endif
1.294 +
1.295 + /*
1.296 + * mPropertiesSet stores a bit for every property that is present,
1.297 + * to optimize compression of blocks with small numbers of
1.298 + * properties (the norm) and to allow quickly checking whether a
1.299 + * property is set in this block.
1.300 + */
1.301 + nsCSSPropertySet mPropertiesSet;
1.302 + /*
1.303 + * mPropertiesImportant indicates which properties are '!important'.
1.304 + */
1.305 + nsCSSPropertySet mPropertiesImportant;
1.306 +
1.307 + /*
1.308 + * Return the storage location within |this| of the value of the
1.309 + * property |aProperty|.
1.310 + */
1.311 + nsCSSValue* PropertyAt(nsCSSProperty aProperty) {
1.312 + NS_ABORT_IF_FALSE(0 <= aProperty &&
1.313 + aProperty < eCSSProperty_COUNT_no_shorthands,
1.314 + "property out of range");
1.315 + return &mValues[aProperty];
1.316 + }
1.317 + const nsCSSValue* PropertyAt(nsCSSProperty aProperty) const {
1.318 + NS_ABORT_IF_FALSE(0 <= aProperty &&
1.319 + aProperty < eCSSProperty_COUNT_no_shorthands,
1.320 + "property out of range");
1.321 + return &mValues[aProperty];
1.322 + }
1.323 +
1.324 + void SetPropertyBit(nsCSSProperty aProperty) {
1.325 + mPropertiesSet.AddProperty(aProperty);
1.326 + }
1.327 +
1.328 + void ClearPropertyBit(nsCSSProperty aProperty) {
1.329 + mPropertiesSet.RemoveProperty(aProperty);
1.330 + }
1.331 +
1.332 + bool HasPropertyBit(nsCSSProperty aProperty) {
1.333 + return mPropertiesSet.HasProperty(aProperty);
1.334 + }
1.335 +
1.336 + void SetImportantBit(nsCSSProperty aProperty) {
1.337 + mPropertiesImportant.AddProperty(aProperty);
1.338 + }
1.339 +
1.340 + void ClearImportantBit(nsCSSProperty aProperty) {
1.341 + mPropertiesImportant.RemoveProperty(aProperty);
1.342 + }
1.343 +
1.344 + bool HasImportantBit(nsCSSProperty aProperty) {
1.345 + return mPropertiesImportant.HasProperty(aProperty);
1.346 + }
1.347 +
1.348 + void ClearSets() {
1.349 + mPropertiesSet.Empty();
1.350 + mPropertiesImportant.Empty();
1.351 + }
1.352 +};
1.353 +
1.354 +#endif /* !defined(nsCSSDataBlock_h__) */
