Package org.mozilla.javascript
Class LambdaConstructor
- java.lang.Object
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- org.mozilla.javascript.ScriptableObject
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- org.mozilla.javascript.IdScriptableObject
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- org.mozilla.javascript.BaseFunction
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- org.mozilla.javascript.LambdaFunction
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- org.mozilla.javascript.LambdaConstructor
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- All Implemented Interfaces:
java.io.Serializable
,Callable
,ConstProperties
,Constructable
,DebuggableObject
,Function
,IdFunctionCall
,Scriptable
,SymbolScriptable
public class LambdaConstructor extends LambdaFunction
This class implements a JavaScript function that may be used as a constructor by delegating to an interface that can be easily implemented as a lambda. The LambdaFunction class may be used to add functions to the prototype that are also implemented as lambdas.In micro benchmarks (as of 2021) using this class to implement a built-in class is about 15% more efficient than using IdScriptableObject, and about 25% faster than using reflection via the ScriptableObject.defineClass() family of methods. Furthermore, it results in code that more directly maps to JavaScript idioms than either methods, it is much easier to implement than IdScriptableObject, and the lambda pattern makes it easier to maintain state in various ways that don't always map directly to the existing concepts.
- See Also:
- Serialized Form
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Nested Class Summary
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Nested classes/interfaces inherited from class org.mozilla.javascript.ScriptableObject
ScriptableObject.KeyComparator
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Field Summary
Fields Modifier and Type Field Description static int
CONSTRUCTOR_DEFAULT
By default, the constructor may be invoked either waystatic int
CONSTRUCTOR_FUNCTION
If this flag is set, the constructor may be invoked as an ordinary functionstatic int
CONSTRUCTOR_NEW
If this flag is set, the constructor may be invoked using "new"private int
flags
private static long
serialVersionUID
private Constructable
targetConstructor
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Fields inherited from class org.mozilla.javascript.BaseFunction
GENERATOR_FUNCTION_CLASS
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Fields inherited from class org.mozilla.javascript.ScriptableObject
CONST, DONTENUM, EMPTY, PERMANENT, READONLY, UNINITIALIZED_CONST
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Fields inherited from interface org.mozilla.javascript.Scriptable
NOT_FOUND
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Constructor Summary
Constructors Constructor Description LambdaConstructor(Scriptable scope, java.lang.String name, int length, int flags, Constructable target)
Create a new function and control whether it may be invoked using new, as a function, or both.LambdaConstructor(Scriptable scope, java.lang.String name, int length, Constructable target)
Create a new function that may be used as a constructor.
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description java.lang.Object
call(Context cx, Scriptable scope, Scriptable thisObj, java.lang.Object[] args)
Should be overridden.Scriptable
construct(Context cx, Scriptable scope, java.lang.Object[] args)
Call the function as a constructor.static <T> T
convertThisObject(Scriptable thisObj, java.lang.Class<T> targetClass)
A convenience method to convert JavaScript's "this" object into a target class and throw a TypeError if it does not match.void
defineConstructorMethod(Scriptable scope, java.lang.String name, int length, Callable target, int attributes)
Define a function property directly on the constructor that is implemented under the covers by a LambdaFunction.void
defineConstructorMethod(Scriptable scope, java.lang.String name, int length, Callable target, int attributes, int propertyAttributes)
Define a function property directly on the constructor that is implemented under the covers by a LambdaFunction, and override the properties of its "name", "length", and "arity" properties.void
defineConstructorMethod(Scriptable scope, Symbol key, java.lang.String name, int length, Callable target, int attributes)
Define a function property directly on the constructor that is implemented under the covers by a LambdaFunction.void
definePrototypeMethod(Scriptable scope, java.lang.String name, int length, Callable target)
Define a function property on the prototype of the constructor using a LambdaFunction under the covers.void
definePrototypeMethod(Scriptable scope, java.lang.String name, int length, Callable target, int attributes, int propertyAttributes)
Define a function property on the prototype of the constructor using a LambdaFunction under the covers.void
definePrototypeProperty(java.lang.String name, java.lang.Object value, int attributes)
Define a property that may be of any type on the prototype of this constructor.void
definePrototypeProperty(Symbol key, java.lang.Object value, int attributes)
private ScriptableObject
getPrototypeScriptable()
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Methods inherited from class org.mozilla.javascript.LambdaFunction
getArity, getFunctionName, getLength
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Methods inherited from class org.mozilla.javascript.BaseFunction
createObject, decompile, execIdCall, fillConstructorProperties, findInstanceIdInfo, findPrototypeId, getClassName, getClassPrototype, getInstanceIdName, getInstanceIdValue, getMaxInstanceId, getPrototypeProperty, getTypeOf, hasInstance, hasPrototypeProperty, init, initAsGeneratorFunction, initPrototypeId, isApply, isApplyOrCall, isGeneratorFunction, setImmunePrototypeProperty, setInstanceIdAttributes, setInstanceIdValue, setPrototypeProperty, setPrototypePropertyAttributes, setStandardPropertyAttributes, setupDefaultPrototype
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Methods inherited from class org.mozilla.javascript.IdScriptableObject
activatePrototypeMap, addIdFunctionProperty, defaultGet, defaultHas, defaultPut, defineOwnProperty, delete, delete, ensureType, exportAsJSClass, findInstanceIdInfo, findPrototypeId, get, get, getAttributes, getAttributes, getIds, getOwnPropertyDescriptor, has, has, hasPrototypeMap, initPrototypeConstructor, initPrototypeMethod, initPrototypeMethod, initPrototypeMethod, initPrototypeValue, initPrototypeValue, instanceIdInfo, put, put, setAttributes
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Methods inherited from class org.mozilla.javascript.ScriptableObject
addLazilyInitializedValue, applyDescriptorToAttributeBitset, associateValue, avoidObjectDetection, buildClassCtor, buildDataDescriptor, callMethod, callMethod, checkPropertyChange, checkPropertyDefinition, checkValidAttributes, defineClass, defineClass, defineClass, defineConst, defineConstProperty, defineFunctionProperties, defineOwnProperties, defineOwnProperty, defineProperty, defineProperty, defineProperty, defineProperty, defineProperty, defineProperty, delete, deleteProperty, deleteProperty, ensureScriptable, ensureScriptableObject, ensureSymbolScriptable, equivalentValues, get, get, getAllIds, getArrayPrototype, getAssociatedValue, getAttributes, getAttributes, getAttributes, getClassPrototype, getDefaultValue, getDefaultValue, getExternalArrayData, getExternalArrayLength, getFunctionPrototype, getGeneratorFunctionPrototype, getGetterOrSetter, getGetterOrSetter, getIds, getObjectPrototype, getParentScope, getProperty, getProperty, getProperty, getPropertyIds, getPrototype, getTopLevelScope, getTopScopeValue, getTypedProperty, getTypedProperty, has, hasProperty, hasProperty, hasProperty, isAccessorDescriptor, isConst, isDataDescriptor, isEmpty, isExtensible, isFalse, isGenericDescriptor, isGetterOrSetter, isSealed, isTrue, preventExtensions, put, putConst, putConstProperty, putProperty, putProperty, putProperty, querySlot, redefineProperty, sameValue, sealObject, setAttributes, setAttributes, setAttributes, setAttributes, setCommonDescriptorProperties, setExternalArrayData, setGetterOrSetter, setParentScope, setPrototype, size
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Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
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Methods inherited from interface org.mozilla.javascript.Scriptable
delete, delete, get, get, getDefaultValue, getIds, getParentScope, getPrototype, has, has, put, put, setParentScope, setPrototype
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Field Detail
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serialVersionUID
private static final long serialVersionUID
- See Also:
- Constant Field Values
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CONSTRUCTOR_FUNCTION
public static final int CONSTRUCTOR_FUNCTION
If this flag is set, the constructor may be invoked as an ordinary function- See Also:
- Constant Field Values
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CONSTRUCTOR_NEW
public static final int CONSTRUCTOR_NEW
If this flag is set, the constructor may be invoked using "new"- See Also:
- Constant Field Values
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CONSTRUCTOR_DEFAULT
public static final int CONSTRUCTOR_DEFAULT
By default, the constructor may be invoked either way- See Also:
- Constant Field Values
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targetConstructor
private final transient Constructable targetConstructor
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flags
private final int flags
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Constructor Detail
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LambdaConstructor
public LambdaConstructor(Scriptable scope, java.lang.String name, int length, Constructable target)
Create a new function that may be used as a constructor. The new object will have the Function prototype and no parent. The caller is responsible for binding this object to the appropriate scope.- Parameters:
scope
- scope of the calling contextname
- name of the functionlength
- the arity of the functiontarget
- an object that implements the function in Java. Since Constructable is a single-function interface this will typically be implemented as a lambda.
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LambdaConstructor
public LambdaConstructor(Scriptable scope, java.lang.String name, int length, int flags, Constructable target)
Create a new function and control whether it may be invoked using new, as a function, or both.
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Method Detail
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call
public java.lang.Object call(Context cx, Scriptable scope, Scriptable thisObj, java.lang.Object[] args)
Description copied from class:BaseFunction
Should be overridden.- Specified by:
call
in interfaceCallable
- Specified by:
call
in interfaceFunction
- Overrides:
call
in classLambdaFunction
- Parameters:
cx
- the current Context for this threadscope
- the scope to execute the function relative to. This is set to the value returned by getParentScope() except when the function is called from a closure.thisObj
- the JavaScriptthis
objectargs
- the array of arguments- Returns:
- the result of the call
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construct
public Scriptable construct(Context cx, Scriptable scope, java.lang.Object[] args)
Description copied from interface:Function
Call the function as a constructor.This method is invoked by the runtime in order to satisfy a use of the JavaScript
new
operator. This method is expected to create a new object and return it.- Specified by:
construct
in interfaceConstructable
- Specified by:
construct
in interfaceFunction
- Overrides:
construct
in classLambdaFunction
- Parameters:
cx
- the current Context for this threadscope
- an enclosing scope of the caller except when the function is called from a closure.args
- the array of arguments- Returns:
- the allocated object
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definePrototypeMethod
public void definePrototypeMethod(Scriptable scope, java.lang.String name, int length, Callable target)
Define a function property on the prototype of the constructor using a LambdaFunction under the covers.
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definePrototypeMethod
public void definePrototypeMethod(Scriptable scope, java.lang.String name, int length, Callable target, int attributes, int propertyAttributes)
Define a function property on the prototype of the constructor using a LambdaFunction under the covers.
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definePrototypeProperty
public void definePrototypeProperty(java.lang.String name, java.lang.Object value, int attributes)
Define a property that may be of any type on the prototype of this constructor.
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definePrototypeProperty
public void definePrototypeProperty(Symbol key, java.lang.Object value, int attributes)
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defineConstructorMethod
public void defineConstructorMethod(Scriptable scope, java.lang.String name, int length, Callable target, int attributes)
Define a function property directly on the constructor that is implemented under the covers by a LambdaFunction.- Parameters:
name
- the key to use to look up the new function property, and also the value to return for the "name" property of the Function objectlength
- the value to return for the "length" property of the Function objecttarget
- the target to call when the method is invokedattributes
- the attributes to set on the new property
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defineConstructorMethod
public void defineConstructorMethod(Scriptable scope, Symbol key, java.lang.String name, int length, Callable target, int attributes)
Define a function property directly on the constructor that is implemented under the covers by a LambdaFunction.- Parameters:
key
- the Symbol to use to look up the propertyname
- the value to return for the "name" property of the Function objectlength
- the value to return for the "length" property of the Function objecttarget
- the target to call when the method is invokedattributes
- the attributes to set on the new property
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defineConstructorMethod
public void defineConstructorMethod(Scriptable scope, java.lang.String name, int length, Callable target, int attributes, int propertyAttributes)
Define a function property directly on the constructor that is implemented under the covers by a LambdaFunction, and override the properties of its "name", "length", and "arity" properties.
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convertThisObject
public static <T> T convertThisObject(Scriptable thisObj, java.lang.Class<T> targetClass)
A convenience method to convert JavaScript's "this" object into a target class and throw a TypeError if it does not match. This is useful for implementing lambda functions, as "this" in JavaScript doesn't necessarily map to an instance of the class.
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getPrototypeScriptable
private ScriptableObject getPrototypeScriptable()
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