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gecko-dev/layout/style/CSSVariableValues.cpp

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Bug 773296 - Part 7: Add a field to nsStyleVariables to store computed variable values. r=dbaron This defines a class CSSVariableValues which is used to store computed variable values. We store them a bit differently from CSSVariableDeclarations -- here we have a hash table of variable names to integer IDs, and then an array of variables where the array index is the ID. This is because later on we'll want a stable order for the variables to return from DOM APIs. In addition to the string value of the variable, we store the type of the first and last token of the variable value. This information will be used when resolving entire variable reference containing values, to determine when to insert "/**/" before and after a resolved var(blah) token. We add a CSSVariableValues member to nsStyleVariables.
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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 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/. */
/* computed CSS Variable values */
#include "CSSVariableValues.h"
Bug 773296 - Part 8: Resolve and compute CSS variables. r=dbaron We add a new class CSSVariableResolver whose job is to take the inherited computed variables and the specified variable declarations and to perform cycle removal and resolution of the variables, storing the result in the CSSVariableValues object on an nsStyleVariables. We use CSSVariableResolver in nsRuleNode::ComputeVariablesData. The variable resolver does this: 1. Asks the CSSVariableValues and CSSVariableDeclarations objects to add their variables to it. 2. Calls in to a new nsCSSParser function EnumerateVariableReferences that informs the resolver which other variables a given variable references, and by doing so, builds a graph of variable dependencies. 3. Removes variables involved in cyclic references using Tarjan's strongly connected component algorithm, setting those variables to have an invalid value. 4. Calls in to a new nsCSSParser function ResolveVariableValue to resolve the remaining valid variables by substituting variable references. We extend nsCSSParser::ParseValueWithVariables to take a callback function to be invoked when encountering a variable reference. This lets EnumerateVariableReferences re-use ParseValueWithVariables. CSSParserImpl::ResolveValueWithVariableReferences needs different error handling behaviour from ParseValueWithVariables, so we don't re-use it. CSSParserImpl::AppendImpliedEOFCharacters is used to take the value returned from nsCSSScanner::GetImpliedEOFCharacters while resolving variable references that were declared using custom properties that encountered EOF before being closed properly. The SeparatorRequiredBetweenTokens helper function in nsCSSParser.cpp implements the serialization rules in CSS Syntax Module Level 3: https://dvcs.w3.org/hg/csswg/raw-file/3479cdefc59a/css-syntax/Overview.html#serialization
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#include "CSSVariableResolver.h"
Bug 773296 - Part 7: Add a field to nsStyleVariables to store computed variable values. r=dbaron This defines a class CSSVariableValues which is used to store computed variable values. We store them a bit differently from CSSVariableDeclarations -- here we have a hash table of variable names to integer IDs, and then an array of variables where the array index is the ID. This is because later on we'll want a stable order for the variables to return from DOM APIs. In addition to the string value of the variable, we store the type of the first and last token of the variable value. This information will be used when resolving entire variable reference containing values, to determine when to insert "/**/" before and after a resolved var(blah) token. We add a CSSVariableValues member to nsStyleVariables.
2013-12-12 02:09:41 +00:00
namespace mozilla {
CSSVariableValues::CSSVariableValues()
{
MOZ_COUNT_CTOR(CSSVariableValues);
}
CSSVariableValues::CSSVariableValues(const CSSVariableValues& aOther)
{
MOZ_COUNT_CTOR(CSSVariableValues);
CopyVariablesFrom(aOther);
}
#ifdef DEBUG
CSSVariableValues::~CSSVariableValues()
{
MOZ_COUNT_DTOR(CSSVariableValues);
}
#endif
CSSVariableValues&
CSSVariableValues::operator=(const CSSVariableValues& aOther)
{
if (this == &aOther) {
return *this;
}
mVariableIDs.Clear();
mVariables.Clear();
CopyVariablesFrom(aOther);
return *this;
}
Bug 773296 - Part 19: Compare style structs even for the same rule node when variables have changed. r=dbaron This makes updates work correctly when variable values change. Rather than handling nsStyleVariables with a DO_STRUCT_DIFFERENCE, we explicitly compare the two nsStyleVariables objects in nsStyleContext::CalcStyleDifference before looking at the other style structs. This is because we need to force those other style structs to be compared if variable values are changing. nsStyleVariables::CalcDifference still returns 0, since the change in variable values themselves doesn't require any updates.
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bool
CSSVariableValues::operator==(const CSSVariableValues& aOther) const
{
if (mVariables.Length() != aOther.mVariables.Length()) {
return false;
}
for (size_t thisIndex = 0; thisIndex < mVariables.Length(); ++thisIndex) {
size_t otherIndex;
if (!aOther.mVariableIDs.Get(mVariables[thisIndex].mVariableName,
&otherIndex)) {
return false;
}
const nsString& otherValue = aOther.mVariables[otherIndex].mValue;
if (!mVariables[thisIndex].mValue.Equals(otherValue)) {
return false;
}
}
return true;
}
Bug 773296 - Part 22: Expose variables through the nsComputedDOMStyle indexed getter. r=dbaron This exposes the names of the custom properties on a computed style object through its indexed property getter, just after all of the built-in properties.
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size_t
CSSVariableValues::Count() const
{
return mVariables.Length();
}
Bug 773296 - Part 7: Add a field to nsStyleVariables to store computed variable values. r=dbaron This defines a class CSSVariableValues which is used to store computed variable values. We store them a bit differently from CSSVariableDeclarations -- here we have a hash table of variable names to integer IDs, and then an array of variables where the array index is the ID. This is because later on we'll want a stable order for the variables to return from DOM APIs. In addition to the string value of the variable, we store the type of the first and last token of the variable value. This information will be used when resolving entire variable reference containing values, to determine when to insert "/**/" before and after a resolved var(blah) token. We add a CSSVariableValues member to nsStyleVariables.
2013-12-12 02:09:41 +00:00
bool
CSSVariableValues::Get(const nsAString& aName, nsString& aValue) const
{
size_t id;
if (!mVariableIDs.Get(aName, &id)) {
return false;
}
aValue = mVariables[id].mValue;
return true;
}
bool
CSSVariableValues::Get(const nsAString& aName,
nsString& aValue,
nsCSSTokenSerializationType& aFirstToken,
nsCSSTokenSerializationType& aLastToken) const
{
size_t id;
if (!mVariableIDs.Get(aName, &id)) {
return false;
}
aValue = mVariables[id].mValue;
aFirstToken = mVariables[id].mFirstToken;
aLastToken = mVariables[id].mLastToken;
return true;
}
Bug 773296 - Part 22: Expose variables through the nsComputedDOMStyle indexed getter. r=dbaron This exposes the names of the custom properties on a computed style object through its indexed property getter, just after all of the built-in properties.
2013-12-12 02:09:45 +00:00
void
CSSVariableValues::GetVariableAt(size_t aIndex, nsAString& aName) const
{
aName = mVariables[aIndex].mVariableName;
}
Bug 773296 - Part 7: Add a field to nsStyleVariables to store computed variable values. r=dbaron This defines a class CSSVariableValues which is used to store computed variable values. We store them a bit differently from CSSVariableDeclarations -- here we have a hash table of variable names to integer IDs, and then an array of variables where the array index is the ID. This is because later on we'll want a stable order for the variables to return from DOM APIs. In addition to the string value of the variable, we store the type of the first and last token of the variable value. This information will be used when resolving entire variable reference containing values, to determine when to insert "/**/" before and after a resolved var(blah) token. We add a CSSVariableValues member to nsStyleVariables.
2013-12-12 02:09:41 +00:00
void
CSSVariableValues::Put(const nsAString& aName,
nsString aValue,
nsCSSTokenSerializationType aFirstToken,
nsCSSTokenSerializationType aLastToken)
{
size_t id;
if (mVariableIDs.Get(aName, &id)) {
mVariables[id].mValue = aValue;
mVariables[id].mFirstToken = aFirstToken;
mVariables[id].mLastToken = aLastToken;
} else {
id = mVariables.Length();
mVariableIDs.Put(aName, id);
mVariables.AppendElement(Variable(aName, aValue, aFirstToken, aLastToken));
}
}
void
CSSVariableValues::CopyVariablesFrom(const CSSVariableValues& aOther)
{
for (size_t i = 0, n = aOther.mVariables.Length(); i < n; i++) {
Put(aOther.mVariables[i].mVariableName,
aOther.mVariables[i].mValue,
aOther.mVariables[i].mFirstToken,
aOther.mVariables[i].mLastToken);
}
}
Bug 773296 - Part 8: Resolve and compute CSS variables. r=dbaron We add a new class CSSVariableResolver whose job is to take the inherited computed variables and the specified variable declarations and to perform cycle removal and resolution of the variables, storing the result in the CSSVariableValues object on an nsStyleVariables. We use CSSVariableResolver in nsRuleNode::ComputeVariablesData. The variable resolver does this: 1. Asks the CSSVariableValues and CSSVariableDeclarations objects to add their variables to it. 2. Calls in to a new nsCSSParser function EnumerateVariableReferences that informs the resolver which other variables a given variable references, and by doing so, builds a graph of variable dependencies. 3. Removes variables involved in cyclic references using Tarjan's strongly connected component algorithm, setting those variables to have an invalid value. 4. Calls in to a new nsCSSParser function ResolveVariableValue to resolve the remaining valid variables by substituting variable references. We extend nsCSSParser::ParseValueWithVariables to take a callback function to be invoked when encountering a variable reference. This lets EnumerateVariableReferences re-use ParseValueWithVariables. CSSParserImpl::ResolveValueWithVariableReferences needs different error handling behaviour from ParseValueWithVariables, so we don't re-use it. CSSParserImpl::AppendImpliedEOFCharacters is used to take the value returned from nsCSSScanner::GetImpliedEOFCharacters while resolving variable references that were declared using custom properties that encountered EOF before being closed properly. The SeparatorRequiredBetweenTokens helper function in nsCSSParser.cpp implements the serialization rules in CSS Syntax Module Level 3: https://dvcs.w3.org/hg/csswg/raw-file/3479cdefc59a/css-syntax/Overview.html#serialization
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void
CSSVariableValues::AddVariablesToResolver(CSSVariableResolver* aResolver) const
{
for (size_t i = 0, n = mVariables.Length(); i < n; i++) {
aResolver->Put(mVariables[i].mVariableName,
mVariables[i].mValue,
mVariables[i].mFirstToken,
mVariables[i].mLastToken,
true);
}
}
Bug 773296 - Part 7: Add a field to nsStyleVariables to store computed variable values. r=dbaron This defines a class CSSVariableValues which is used to store computed variable values. We store them a bit differently from CSSVariableDeclarations -- here we have a hash table of variable names to integer IDs, and then an array of variables where the array index is the ID. This is because later on we'll want a stable order for the variables to return from DOM APIs. In addition to the string value of the variable, we store the type of the first and last token of the variable value. This information will be used when resolving entire variable reference containing values, to determine when to insert "/**/" before and after a resolved var(blah) token. We add a CSSVariableValues member to nsStyleVariables.
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} // namespace mozilla
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