mirror of
https://github.com/mozilla/gecko-dev.git
synced 2024-12-14 10:43:24 +00:00
267 lines
8.7 KiB
C++
267 lines
8.7 KiB
C++
/* vim: set shiftwidth=2 tabstop=8 autoindent cindent expandtab: */
|
|
/* 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/. */
|
|
|
|
/* object that resolves CSS variables using specified and inherited variable
|
|
* values
|
|
*/
|
|
|
|
#include "CSSVariableResolver.h"
|
|
|
|
#include "CSSVariableDeclarations.h"
|
|
#include "CSSVariableValues.h"
|
|
#include "mozilla/PodOperations.h"
|
|
#include "mozilla/UniquePtr.h"
|
|
#include <algorithm>
|
|
|
|
namespace mozilla {
|
|
|
|
/**
|
|
* Data used by the EnumerateVariableReferences callback. Reset must be called
|
|
* on it before it is used.
|
|
*/
|
|
class EnumerateVariableReferencesData
|
|
{
|
|
public:
|
|
explicit EnumerateVariableReferencesData(CSSVariableResolver& aResolver)
|
|
: mResolver(aResolver)
|
|
, mReferences(MakeUnique<bool[]>(aResolver.mVariables.Length()))
|
|
{
|
|
}
|
|
|
|
/**
|
|
* Resets the data so that it can be passed to another call of
|
|
* EnumerateVariableReferences for a different variable.
|
|
*/
|
|
void Reset()
|
|
{
|
|
PodZero(mReferences.get(), mResolver.mVariables.Length());
|
|
mReferencesNonExistentVariable = false;
|
|
}
|
|
|
|
void RecordVariableReference(const nsAString& aVariableName)
|
|
{
|
|
size_t id;
|
|
if (mResolver.mVariableIDs.Get(aVariableName, &id)) {
|
|
mReferences[id] = true;
|
|
} else {
|
|
mReferencesNonExistentVariable = true;
|
|
}
|
|
}
|
|
|
|
bool HasReferenceToVariable(size_t aID) const
|
|
{
|
|
return mReferences[aID];
|
|
}
|
|
|
|
bool ReferencesNonExistentVariable() const
|
|
{
|
|
return mReferencesNonExistentVariable;
|
|
}
|
|
|
|
private:
|
|
CSSVariableResolver& mResolver;
|
|
|
|
// Array of booleans, where each index is a variable ID. If an element is
|
|
// true, it indicates that the variable we have called
|
|
// EnumerateVariableReferences for has a reference to the variable with
|
|
// that ID.
|
|
const UniquePtr<bool[]> mReferences;
|
|
|
|
// Whether the variable we have called EnumerateVariableReferences for
|
|
// references a variable that does not exist in the resolver.
|
|
bool mReferencesNonExistentVariable;
|
|
};
|
|
|
|
static void
|
|
RecordVariableReference(const nsAString& aVariableName,
|
|
void* aData)
|
|
{
|
|
static_cast<EnumerateVariableReferencesData*>(aData)->
|
|
RecordVariableReference(aVariableName);
|
|
}
|
|
|
|
void
|
|
CSSVariableResolver::RemoveCycles(size_t v)
|
|
{
|
|
mVariables[v].mIndex = mNextIndex;
|
|
mVariables[v].mLowLink = mNextIndex;
|
|
mVariables[v].mInStack = true;
|
|
mStack.AppendElement(v);
|
|
mNextIndex++;
|
|
|
|
for (size_t i = 0, n = mReferences[v].Length(); i < n; i++) {
|
|
size_t w = mReferences[v][i];
|
|
if (!mVariables[w].mIndex) {
|
|
RemoveCycles(w);
|
|
mVariables[v].mLowLink = std::min(mVariables[v].mLowLink,
|
|
mVariables[w].mLowLink);
|
|
} else if (mVariables[w].mInStack) {
|
|
mVariables[v].mLowLink = std::min(mVariables[v].mLowLink,
|
|
mVariables[w].mIndex);
|
|
}
|
|
}
|
|
|
|
if (mVariables[v].mLowLink == mVariables[v].mIndex) {
|
|
if (mStack.LastElement() == v) {
|
|
// A strongly connected component consisting of a single variable is not
|
|
// necessarily invalid. We handle variables that reference themselves
|
|
// earlier, in CSSVariableResolver::Resolve.
|
|
mVariables[mStack.LastElement()].mInStack = false;
|
|
mStack.TruncateLength(mStack.Length() - 1);
|
|
} else {
|
|
size_t w;
|
|
do {
|
|
w = mStack.LastElement();
|
|
mVariables[w].mValue.Truncate(0);
|
|
mVariables[w].mInStack = false;
|
|
mStack.TruncateLength(mStack.Length() - 1);
|
|
} while (w != v);
|
|
}
|
|
}
|
|
}
|
|
|
|
void
|
|
CSSVariableResolver::ResolveVariable(size_t aID)
|
|
{
|
|
if (mVariables[aID].mValue.IsEmpty() || mVariables[aID].mWasInherited) {
|
|
// The variable is invalid or was inherited. We can just copy the value
|
|
// and its first/last token information across.
|
|
mOutput->Put(mVariables[aID].mVariableName,
|
|
mVariables[aID].mValue,
|
|
mVariables[aID].mFirstToken,
|
|
mVariables[aID].mLastToken);
|
|
} else {
|
|
// Otherwise we need to resolve the variable references, after resolving
|
|
// all of our dependencies first. We do this even for variables that we
|
|
// know do not reference other variables so that we can find their
|
|
// first/last token.
|
|
//
|
|
// XXX We might want to do this first/last token finding during
|
|
// EnumerateVariableReferences, so that we can avoid calling
|
|
// ResolveVariableValue and parsing the value again.
|
|
for (size_t i = 0, n = mReferences[aID].Length(); i < n; i++) {
|
|
size_t j = mReferences[aID][i];
|
|
if (aID != j && !mVariables[j].mResolved) {
|
|
ResolveVariable(j);
|
|
}
|
|
}
|
|
nsString resolvedValue;
|
|
nsCSSTokenSerializationType firstToken, lastToken;
|
|
if (!mParser.ResolveVariableValue(mVariables[aID].mValue, mOutput,
|
|
resolvedValue, firstToken, lastToken)) {
|
|
resolvedValue.Truncate(0);
|
|
}
|
|
mOutput->Put(mVariables[aID].mVariableName, resolvedValue,
|
|
firstToken, lastToken);
|
|
}
|
|
mVariables[aID].mResolved = true;
|
|
}
|
|
|
|
void
|
|
CSSVariableResolver::Resolve(const CSSVariableValues* aInherited,
|
|
const CSSVariableDeclarations* aSpecified)
|
|
{
|
|
MOZ_ASSERT(!mResolved);
|
|
|
|
// The only time we would be worried about having a null aInherited is
|
|
// for the root, but in that case nsRuleNode::ComputeVariablesData will
|
|
// happen to pass in whatever we're using as mOutput for aInherited,
|
|
// which will initially be empty.
|
|
MOZ_ASSERT(aInherited);
|
|
MOZ_ASSERT(aSpecified);
|
|
|
|
aInherited->AddVariablesToResolver(this);
|
|
aSpecified->AddVariablesToResolver(this);
|
|
|
|
// First we look at each variable's value and record which other variables
|
|
// it references.
|
|
size_t n = mVariables.Length();
|
|
mReferences.SetLength(n);
|
|
EnumerateVariableReferencesData data(*this);
|
|
for (size_t id = 0; id < n; id++) {
|
|
data.Reset();
|
|
if (!mVariables[id].mWasInherited &&
|
|
!mVariables[id].mValue.IsEmpty()) {
|
|
if (mParser.EnumerateVariableReferences(mVariables[id].mValue,
|
|
RecordVariableReference,
|
|
&data)) {
|
|
// Convert the boolean array of dependencies in |data| to a list
|
|
// of dependencies.
|
|
for (size_t i = 0; i < n; i++) {
|
|
if (data.HasReferenceToVariable(i)) {
|
|
mReferences[id].AppendElement(i);
|
|
}
|
|
}
|
|
// If a variable references itself, it is invalid. (RemoveCycles
|
|
// does not check for cycles consisting of a single variable, so we
|
|
// check here.)
|
|
if (data.HasReferenceToVariable(id)) {
|
|
mVariables[id].mValue.Truncate();
|
|
}
|
|
// Also record whether it referenced any variables that don't exist
|
|
// in the resolver, so that we can ensure we still resolve its value
|
|
// in ResolveVariable, even though its mReferences list is empty.
|
|
mVariables[id].mReferencesNonExistentVariable =
|
|
data.ReferencesNonExistentVariable();
|
|
} else {
|
|
MOZ_ASSERT(false, "EnumerateVariableReferences should not have failed "
|
|
"if we previously parsed the specified value");
|
|
mVariables[id].mValue.Truncate(0);
|
|
}
|
|
}
|
|
}
|
|
|
|
// Next we remove any cycles in variable references using Tarjan's strongly
|
|
// connected components finding algorithm, setting variables in cycles to
|
|
// have an invalid value.
|
|
mNextIndex = 1;
|
|
for (size_t id = 0; id < n; id++) {
|
|
if (!mVariables[id].mIndex) {
|
|
RemoveCycles(id);
|
|
MOZ_ASSERT(mStack.IsEmpty());
|
|
}
|
|
}
|
|
|
|
// Finally we construct the computed value for the variable by substituting
|
|
// any variable references.
|
|
for (size_t id = 0; id < n; id++) {
|
|
if (!mVariables[id].mResolved) {
|
|
ResolveVariable(id);
|
|
}
|
|
}
|
|
|
|
#ifdef DEBUG
|
|
mResolved = true;
|
|
#endif
|
|
}
|
|
|
|
void
|
|
CSSVariableResolver::Put(const nsAString& aVariableName,
|
|
nsString aValue,
|
|
nsCSSTokenSerializationType aFirstToken,
|
|
nsCSSTokenSerializationType aLastToken,
|
|
bool aWasInherited)
|
|
{
|
|
MOZ_ASSERT(!mResolved);
|
|
|
|
size_t id;
|
|
if (mVariableIDs.Get(aVariableName, &id)) {
|
|
MOZ_ASSERT(mVariables[id].mWasInherited && !aWasInherited,
|
|
"should only overwrite inherited variables with specified "
|
|
"variables");
|
|
mVariables[id].mValue = aValue;
|
|
mVariables[id].mFirstToken = aFirstToken;
|
|
mVariables[id].mLastToken = aLastToken;
|
|
mVariables[id].mWasInherited = aWasInherited;
|
|
} else {
|
|
id = mVariables.Length();
|
|
mVariableIDs.Put(aVariableName, id);
|
|
mVariables.AppendElement(Variable(aVariableName, aValue,
|
|
aFirstToken, aLastToken, aWasInherited));
|
|
}
|
|
}
|
|
|
|
} // namespace mozilla
|