[844] | 1 | /****************************************************************************
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| 2 | **
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| 3 | ** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
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| 4 | ** All rights reserved.
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| 5 | ** Contact: Nokia Corporation ([email protected])
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| 6 | **
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| 7 | ** This file is part of the QtScript module of the Qt Toolkit.
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| 8 | **
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| 9 | ** $QT_BEGIN_LICENSE:LGPL-ONLY$
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| 10 | ** GNU Lesser General Public License Usage
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| 11 | ** This file may be used under the terms of the GNU Lesser
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| 12 | ** General Public License version 2.1 as published by the Free Software
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| 13 | ** Foundation and appearing in the file LICENSE.LGPL included in the
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| 14 | ** packaging of this file. Please review the following information to
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| 15 | ** ensure the GNU Lesser General Public License version 2.1 requirements
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| 16 | ** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
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| 17 | **
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| 18 | ** If you have questions regarding the use of this file, please contact
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| 19 | ** Nokia at [email protected].
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| 20 | ** $QT_END_LICENSE$
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| 21 | **
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| 22 | ****************************************************************************/
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| 23 |
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| 24 | #include "config.h"
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| 25 | #include "qscriptstaticscopeobject_p.h"
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| 26 |
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| 27 | namespace JSC
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| 28 | {
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| 29 | ASSERT_CLASS_FITS_IN_CELL(QT_PREPEND_NAMESPACE(QScriptStaticScopeObject));
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| 30 | }
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| 31 |
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| 32 | QT_BEGIN_NAMESPACE
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| 33 |
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| 34 | /*!
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| 35 | \class QScriptStaticScopeObject
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| 36 | \internal
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| 37 |
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| 38 | Represents a static scope object.
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| 39 |
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| 40 | This class allows the VM to determine at JS script compile time whether
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| 41 | the object has a given property or not. If the object has the property,
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| 42 | a fast, index-based read/write operation will be used. If the object
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| 43 | doesn't have the property, the compiler knows it can safely skip this
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| 44 | object when dynamically resolving the property. Either way, this can
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| 45 | greatly improve performance.
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| 46 |
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| 47 | \sa QScriptContext::pushScope()
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| 48 | */
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| 49 |
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| 50 | const JSC::ClassInfo QScriptStaticScopeObject::info = { "QScriptStaticScopeObject", 0, 0, 0 };
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| 51 |
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| 52 | /*!
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| 53 | Creates a static scope object with a fixed set of undeletable properties.
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| 54 |
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| 55 | It's not possible to add new properties to the object after construction.
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| 56 | */
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| 57 | QScriptStaticScopeObject::QScriptStaticScopeObject(WTF::NonNullPassRefPtr<JSC::Structure> structure,
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| 58 | int propertyCount, const PropertyInfo* props)
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| 59 | : JSC::JSVariableObject(structure, new Data(/*canGrow=*/false))
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| 60 | {
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| 61 | int index = growRegisterArray(propertyCount);
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| 62 | for (int i = 0; i < propertyCount; ++i, --index) {
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| 63 | const PropertyInfo& prop = props[i];
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| 64 | JSC::SymbolTableEntry entry(index, prop.attributes);
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| 65 | symbolTable().add(prop.identifier.ustring().rep(), entry);
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| 66 | registerAt(index) = prop.value;
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| 67 | }
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| 68 | }
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| 69 |
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| 70 | /*!
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| 71 | Creates an empty static scope object.
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| 72 |
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| 73 | Properties can be added to the object after construction, either by
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| 74 | calling QScriptValue::setProperty(), or by pushing the object on the
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| 75 | scope chain; variable declarations ("var" statements) and function
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| 76 | declarations in JavaScript will create properties on the scope object.
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| 77 |
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| 78 | Note that once the scope object has been used in a closure and the
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| 79 | resulting function has been compiled, it's no longer safe to add
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| 80 | properties to the scope object (because the VM will bypass this
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| 81 | object the next time the function is executed).
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| 82 | */
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| 83 | QScriptStaticScopeObject::QScriptStaticScopeObject(WTF::NonNullPassRefPtr<JSC::Structure> structure)
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| 84 | : JSC::JSVariableObject(structure, new Data(/*canGrow=*/true))
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| 85 | {
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| 86 | }
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| 87 |
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| 88 | QScriptStaticScopeObject::~QScriptStaticScopeObject()
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| 89 | {
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| 90 | delete d_ptr();
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| 91 | }
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| 92 |
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| 93 | bool QScriptStaticScopeObject::getOwnPropertySlot(JSC::ExecState*, const JSC::Identifier& propertyName, JSC::PropertySlot& slot)
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| 94 | {
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| 95 | return symbolTableGet(propertyName, slot);
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| 96 | }
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| 97 |
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| 98 | bool QScriptStaticScopeObject::getOwnPropertyDescriptor(JSC::ExecState*, const JSC::Identifier& propertyName, JSC::PropertyDescriptor& descriptor)
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| 99 | {
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| 100 | return symbolTableGet(propertyName, descriptor);
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| 101 | }
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| 102 |
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| 103 | void QScriptStaticScopeObject::putWithAttributes(JSC::ExecState* exec, const JSC::Identifier &propertyName, JSC::JSValue value, unsigned attributes)
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| 104 | {
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| 105 | if (symbolTablePutWithAttributes(propertyName, value, attributes))
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| 106 | return;
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| 107 | Q_ASSERT(d_ptr()->canGrow);
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| 108 | addSymbolTableProperty(propertyName, value, attributes);
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| 109 | }
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| 110 |
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| 111 | void QScriptStaticScopeObject::put(JSC::ExecState* exec, const JSC::Identifier& propertyName, JSC::JSValue value, JSC::PutPropertySlot&)
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| 112 | {
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| 113 | if (symbolTablePut(propertyName, value))
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| 114 | return;
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| 115 | Q_ASSERT(d_ptr()->canGrow);
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| 116 | addSymbolTableProperty(propertyName, value, /*attributes=*/0);
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| 117 | }
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| 118 |
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| 119 | bool QScriptStaticScopeObject::deleteProperty(JSC::ExecState*, const JSC::Identifier&)
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| 120 | {
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| 121 | return false;
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| 122 | }
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| 123 |
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| 124 | void QScriptStaticScopeObject::markChildren(JSC::MarkStack& markStack)
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| 125 | {
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| 126 | JSC::Register* registerArray = d_ptr()->registerArray.get();
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| 127 | if (!registerArray)
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| 128 | return;
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| 129 | markStack.appendValues(reinterpret_cast<JSC::JSValue*>(registerArray), d_ptr()->registerArraySize);
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| 130 | }
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| 131 |
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| 132 | void QScriptStaticScopeObject::addSymbolTableProperty(const JSC::Identifier& name, JSC::JSValue value, unsigned attributes)
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| 133 | {
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| 134 | int index = growRegisterArray(1);
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| 135 | JSC::SymbolTableEntry newEntry(index, attributes | JSC::DontDelete);
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| 136 | symbolTable().add(name.ustring().rep(), newEntry);
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| 137 | registerAt(index) = value;
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| 138 | }
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| 139 |
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| 140 | /*!
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| 141 | Grows the register array by \a count elements, and returns the offset of
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| 142 | the newly added elements (note that the register file grows downwards,
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| 143 | starting at index -1).
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| 144 | */
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| 145 | int QScriptStaticScopeObject::growRegisterArray(int count)
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| 146 | {
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| 147 | size_t oldSize = d_ptr()->registerArraySize;
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| 148 | size_t newSize = oldSize + count;
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| 149 | JSC::Register* registerArray = new JSC::Register[newSize];
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| 150 | if (d_ptr()->registerArray)
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| 151 | memcpy(registerArray + count, d_ptr()->registerArray.get(), oldSize * sizeof(JSC::Register));
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| 152 | setRegisters(registerArray + newSize, registerArray);
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| 153 | d_ptr()->registerArraySize = newSize;
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| 154 | return -oldSize - 1;
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