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QXmlStream: don't create QStrings just to look up entities in a hash

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Move the entity's name into the Entity struct and use a QStringView
into Entity::name as the hash key, instead of a QString.

This avoids having to create a QString from QStringRefs every time an
entity is looked up.

Only costs 280B in text size on optimized GCC 6.1 Linux AMD64 builds.

Change-Id: I8dbd04c90c1ff684b794685025204abc89f68a84
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
This commit is contained in:
Marc Mutz 2017-04-15 14:25:54 +02:00
parent e136565505
commit dc72ff7b97
3 changed files with 63 additions and 39 deletions
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16
src/corelib/xml/qxmlstream.cpp
View File

@ -796,11 +796,17 @@ QXmlStreamReaderPrivate::QXmlStreamReaderPrivate(QXmlStreamReader *q)
reallocateStack();
entityResolver = 0;
init();
entityHash.insert(QLatin1String("lt"), Entity::createLiteral(QLatin1String("<")));
entityHash.insert(QLatin1String("gt"), Entity::createLiteral(QLatin1String(">")));
entityHash.insert(QLatin1String("amp"), Entity::createLiteral(QLatin1String("&")));
entityHash.insert(QLatin1String("apos"), Entity::createLiteral(QLatin1String("'")));
entityHash.insert(QLatin1String("quot"), Entity::createLiteral(QLatin1String("\"")));
#define ADD_PREDEFINED(n, v) \
do { \
Entity e = Entity::createLiteral(QLatin1String(n), QLatin1String(v)); \
entityHash.insert(qToStringViewIgnoringNull(e.name), std::move(e)); \
} while (false)
ADD_PREDEFINED("lt", "<");
ADD_PREDEFINED("gt", ">");
ADD_PREDEFINED("amp", "&");
ADD_PREDEFINED("apos", "'");
ADD_PREDEFINED("quot", "\"");
#undef ADD_PREDEFINED
}
void QXmlStreamReaderPrivate::init()

43
src/corelib/xml/qxmlstream.g
View File

@ -258,20 +258,24 @@ public:
int readBufferPos;
QXmlStreamSimpleStack<uint> putStack;
struct Entity {
Entity(const QString& str = QString())
:value(str), external(false), unparsed(false), literal(false),
Entity() = default;
Entity(const QString &name, const QString &value)
: name(name), value(value), external(false), unparsed(false), literal(false),
hasBeenParsed(false), isCurrentlyReferenced(false){}
static inline Entity createLiteral(const QString &entity)
{ Entity result(entity); result.literal = result.hasBeenParsed = true; return result; }
QString value;
static inline Entity createLiteral(QLatin1String name, QLatin1String value)
{ Entity result(name, value); result.literal = result.hasBeenParsed = true; return result; }
QString name, value;
uint external : 1;
uint unparsed : 1;
uint literal : 1;
uint hasBeenParsed : 1;
uint isCurrentlyReferenced : 1;
};
QHash<QString, Entity> entityHash;
QHash<QString, Entity> parameterEntityHash;
// these hash tables use a QStringView as a key to avoid creating QStrings
// just for lookup. The keys are usually views into Entity::name and thus
// are guaranteed to have the same lifetime as the referenced data:
QHash<QStringView, Entity> entityHash;
QHash<QStringView, Entity> parameterEntityHash;
QXmlStreamSimpleStack<Entity *>entityReferenceStack;
inline bool referenceEntity(Entity &entity) {
if (entity.isCurrentlyReferenced) {
@ -424,6 +428,11 @@ public:
const Value &symbol = sym(index);
return QStringRef(&textBuffer, symbol.pos + symbol.prefix, symbol.len - symbol.prefix);
}
QStringView symView(int index) const
{
const Value &symbol = sym(index);
return QStringView(textBuffer.data() + symbol.pos, symbol.len).mid(symbol.prefix);
}
inline QStringRef symName(int index) {
const Value &symbol = sym(index);
return QStringRef(&textBuffer, symbol.pos, symbol.len);
@ -1142,13 +1151,13 @@ entity_decl ::= entity_decl_start entity_value space_opt RANGLE;
EntityDeclaration &entityDeclaration = entityDeclarations.top();
if (!entityDeclaration.external)
entityDeclaration.value = symString(2);
QString entityName = entityDeclaration.name.toString();
QHash<QString, Entity> &hash = entityDeclaration.parameter ? parameterEntityHash : entityHash;
if (!hash.contains(entityName)) {
Entity entity(entityDeclaration.value.toString());
auto &hash = entityDeclaration.parameter ? parameterEntityHash : entityHash;
if (!hash.contains(qToStringViewIgnoringNull(entityDeclaration.name))) {
Entity entity(entityDeclaration.name.toString(),
entityDeclaration.value.toString());
entity.unparsed = (!entityDeclaration.notationName.isNull());
entity.external = entityDeclaration.external;
hash.insert(entityName, entity);
hash.insert(qToStringViewIgnoringNull(entity.name), entity);
}
} break;
./
@ -1612,7 +1621,7 @@ entity_ref ::= AMPERSAND name SEMICOLON;
/.
case $rule_number: {
sym(1).len += sym(2).len + 1;
QString reference = symString(2).toString();
QStringView reference = symView(2);
if (entityHash.contains(reference)) {
Entity &entity = entityHash[reference];
if (entity.unparsed) {
@ -1633,7 +1642,7 @@ entity_ref ::= AMPERSAND name SEMICOLON;
}
if (entityResolver) {
QString replacementText = resolveUndeclaredEntity(reference);
QString replacementText = resolveUndeclaredEntity(reference.toString());
if (!replacementText.isNull()) {
putReplacement(replacementText);
textBuffer.chop(2 + sym(2).len);
@ -1654,7 +1663,7 @@ pereference ::= PERCENT name SEMICOLON;
/.
case $rule_number: {
sym(1).len += sym(2).len + 1;
QString reference = symString(2).toString();
QStringView reference = symView(2);
if (parameterEntityHash.contains(reference)) {
referenceToParameterEntityDetected = true;
Entity &entity = parameterEntityHash[reference];
@ -1685,7 +1694,7 @@ entity_ref_in_attribute_value ::= AMPERSAND name SEMICOLON;
/.
case $rule_number: {
sym(1).len += sym(2).len + 1;
QString reference = symString(2).toString();
QStringView reference = symView(2);
if (entityHash.contains(reference)) {
Entity &entity = entityHash[reference];
if (entity.unparsed || entity.value.isNull()) {
@ -1706,7 +1715,7 @@ entity_ref_in_attribute_value ::= AMPERSAND name SEMICOLON;
}
if (entityResolver) {
QString replacementText = resolveUndeclaredEntity(reference);
QString replacementText = resolveUndeclaredEntity(reference.toString());
if (!replacementText.isNull()) {
putReplacement(replacementText);
textBuffer.chop(2 + sym(2).len);

43
src/corelib/xml/qxmlstream_p.h
View File

@ -754,20 +754,24 @@ public:
int readBufferPos;
QXmlStreamSimpleStack<uint> putStack;
struct Entity {
Entity(const QString& str = QString())
:value(str), external(false), unparsed(false), literal(false),
Entity() = default;
Entity(const QString &name, const QString &value)
: name(name), value(value), external(false), unparsed(false), literal(false),
hasBeenParsed(false), isCurrentlyReferenced(false){}
static inline Entity createLiteral(const QString &entity)
{ Entity result(entity); result.literal = result.hasBeenParsed = true; return result; }
QString value;
static inline Entity createLiteral(QLatin1String name, QLatin1String value)
{ Entity result(name, value); result.literal = result.hasBeenParsed = true; return result; }
QString name, value;
uint external : 1;
uint unparsed : 1;
uint literal : 1;
uint hasBeenParsed : 1;
uint isCurrentlyReferenced : 1;
};
QHash<QString, Entity> entityHash;
QHash<QString, Entity> parameterEntityHash;
// these hash tables use a QStringView as a key to avoid creating QStrings
// just for lookup. The keys are usually views into Entity::name and thus
// are guaranteed to have the same lifetime as the referenced data:
QHash<QStringView, Entity> entityHash;
QHash<QStringView, Entity> parameterEntityHash;
QXmlStreamSimpleStack<Entity *>entityReferenceStack;
inline bool referenceEntity(Entity &entity) {
if (entity.isCurrentlyReferenced) {
@ -920,6 +924,11 @@ public:
const Value &symbol = sym(index);
return QStringRef(&textBuffer, symbol.pos + symbol.prefix, symbol.len - symbol.prefix);
}
QStringView symView(int index) const
{
const Value &symbol = sym(index);
return QStringView(textBuffer.data() + symbol.pos, symbol.len).mid(symbol.prefix);
}
inline QStringRef symName(int index) {
const Value &symbol = sym(index);
return QStringRef(&textBuffer, symbol.pos, symbol.len);
@ -1490,13 +1499,13 @@ bool QXmlStreamReaderPrivate::parse()
EntityDeclaration &entityDeclaration = entityDeclarations.top();
if (!entityDeclaration.external)
entityDeclaration.value = symString(2);
QString entityName = entityDeclaration.name.toString();
QHash<QString, Entity> &hash = entityDeclaration.parameter ? parameterEntityHash : entityHash;
if (!hash.contains(entityName)) {
Entity entity(entityDeclaration.value.toString());
auto &hash = entityDeclaration.parameter ? parameterEntityHash : entityHash;
if (!hash.contains(qToStringViewIgnoringNull(entityDeclaration.name))) {
Entity entity(entityDeclaration.name.toString(),
entityDeclaration.value.toString());
entity.unparsed = (!entityDeclaration.notationName.isNull());
entity.external = entityDeclaration.external;
hash.insert(entityName, entity);
hash.insert(qToStringViewIgnoringNull(entity.name), entity);
}
} break;
@ -1791,7 +1800,7 @@ bool QXmlStreamReaderPrivate::parse()
case 240: {
sym(1).len += sym(2).len + 1;
QString reference = symString(2).toString();
QStringView reference = symView(2);
if (entityHash.contains(reference)) {
Entity &entity = entityHash[reference];
if (entity.unparsed) {
@ -1812,7 +1821,7 @@ bool QXmlStreamReaderPrivate::parse()
}
if (entityResolver) {
QString replacementText = resolveUndeclaredEntity(reference);
QString replacementText = resolveUndeclaredEntity(reference.toString());
if (!replacementText.isNull()) {
putReplacement(replacementText);
textBuffer.chop(2 + sym(2).len);
@ -1830,7 +1839,7 @@ bool QXmlStreamReaderPrivate::parse()
case 241: {
sym(1).len += sym(2).len + 1;
QString reference = symString(2).toString();
QStringView reference = symView(2);
if (parameterEntityHash.contains(reference)) {
referenceToParameterEntityDetected = true;
Entity &entity = parameterEntityHash[reference];
@ -1853,7 +1862,7 @@ bool QXmlStreamReaderPrivate::parse()
case 243: {
sym(1).len += sym(2).len + 1;
QString reference = symString(2).toString();
QStringView reference = symView(2);
if (entityHash.contains(reference)) {
Entity &entity = entityHash[reference];
if (entity.unparsed || entity.value.isNull()) {
@ -1874,7 +1883,7 @@ bool QXmlStreamReaderPrivate::parse()
}
if (entityResolver) {
QString replacementText = resolveUndeclaredEntity(reference);
QString replacementText = resolveUndeclaredEntity(reference.toString());
if (!replacementText.isNull()) {
putReplacement(replacementText);
textBuffer.chop(2 + sym(2).len);