public class TopLevel extends IdScriptableObject
ECMA 262 requires that most constructors used internally construct objects with the original prototype object as value of their [[Prototype]] internal property. Since built-in global constructors are defined as writable and deletable, this means they should be cached to protect against redefinition at runtime.
In order to implement this efficiently, this class provides a mechanism
to access the original built-in global constructors and their prototypes
via numeric class-ids. To make use of this, the new
ScriptRuntime.newBuiltinObject and
ScriptRuntime.setBuiltinProtoAndParent
methods should be used to create and initialize objects of built-in classes
instead of their generic counterparts.
Calling Context.initStandardObjects()
with an instance of this class as argument will automatically cache
built-in classes after initialization. For other setups involving
top-level scopes that inherit global properties from their proptotypes
(e.g. with dynamic scopes) embeddings should explicitly call
cacheBuiltins() to initialize the class cache for each top-level
scope.
| Modifier and Type | Class and Description |
|---|---|
static class |
TopLevel.Builtins
An enumeration of built-in ECMAScript objects.
|
CONST, DONTENUM, EMPTY, PERMANENT, READONLY, UNINITIALIZED_CONSTNOT_FOUND| Constructor and Description |
|---|
TopLevel() |
| Modifier and Type | Method and Description |
|---|---|
void |
cacheBuiltins()
Cache the built-in ECMAScript objects to protect them against
modifications by the script.
|
static Function |
getBuiltinCtor(Context cx,
Scriptable scope,
TopLevel.Builtins type)
Static helper method to get a built-in object constructor with the given
type from the given scope. |
BaseFunction |
getBuiltinCtor(TopLevel.Builtins type)
Get the cached built-in object constructor from this scope with the
given
type. |
static Scriptable |
getBuiltinPrototype(Scriptable scope,
TopLevel.Builtins type)
Static helper method to get a built-in object prototype with the given
type from the given scope. |
Scriptable |
getBuiltinPrototype(TopLevel.Builtins type)
Get the cached built-in object prototype from this scope with the
given
type. |
java.lang.String |
getClassName()
Return the name of the class.
|
activatePrototypeMap, addIdFunctionProperty, defaultGet, defaultPut, defineOwnProperty, delete, execIdCall, exportAsJSClass, fillConstructorProperties, findInstanceIdInfo, findPrototypeId, get, getAttributes, getInstanceIdName, getInstanceIdValue, getMaxInstanceId, getOwnPropertyDescriptor, has, hasPrototypeMap, incompatibleCallError, initPrototypeConstructor, initPrototypeId, initPrototypeMethod, initPrototypeValue, instanceIdInfo, put, setAttributes, setInstanceIdAttributes, setInstanceIdValueapplyDescriptorToAttributeBitset, associateValue, avoidObjectDetection, buildDataDescriptor, callMethod, callMethod, checkPropertyChange, checkPropertyDefinition, defineClass, defineClass, defineClass, defineConst, defineConstProperty, defineFunctionProperties, defineOwnProperties, defineOwnProperty, defineProperty, defineProperty, defineProperty, defineProperty, delete, deleteProperty, deleteProperty, ensureScriptable, ensureScriptableObject, equivalentValues, get, get, getAllIds, getArrayPrototype, getAssociatedValue, getAttributes, getAttributes, getAttributes, getClassPrototype, getDefaultValue, getDefaultValue, getFunctionPrototype, getGetterOrSetter, getIds, getObjectPrototype, getParentScope, getProperty, getProperty, getPropertyIds, getPrototype, getSlot, getTopLevelScope, getTopScopeValue, getTypedProperty, getTypedProperty, getTypeOf, has, hasInstance, hasProperty, hasProperty, isAccessorDescriptor, isConst, isDataDescriptor, isEmpty, isExtensible, isFalse, isGenericDescriptor, isGetterOrSetter, isSealed, isTrue, preventExtensions, put, putConst, putConstProperty, putProperty, putProperty, redefineProperty, sameValue, sealObject, setAttributes, setAttributes, setAttributes, setGetterOrSetter, setParentScope, setPrototype, sizepublic java.lang.String getClassName()
ScriptableObjectgetClassName in interface ScriptablegetClassName in class ScriptableObjectpublic void cacheBuiltins()
ScriptRuntime.initStandardObjects
if the scope argument is an instance of this class. It only has to be
called by the embedding if a top-level scope is not initialized through
initStandardObjects().public static Function getBuiltinCtor(Context cx, Scriptable scope, TopLevel.Builtins type)
type from the given scope. If the scope is not
an instance of this class or does have a cache of built-ins,
the constructor is looked up via normal property lookup.cx - the current Contextscope - the top-level scopetype - the built-in typepublic static Scriptable getBuiltinPrototype(Scriptable scope, TopLevel.Builtins type)
type from the given scope. If the scope is not
an instance of this class or does have a cache of built-ins,
the prototype is looked up via normal property lookup.scope - the top-level scopetype - the built-in typepublic BaseFunction getBuiltinCtor(TopLevel.Builtins type)
type. Returns null if cacheBuiltins() has not
been called on this object.type - the built-in typepublic Scriptable getBuiltinPrototype(TopLevel.Builtins type)
type. Returns null if cacheBuiltins() has not
been called on this object.type - the built-in type