JavaScript: Class ScriptableObject

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org.mozilla.javascript
Class ScriptableObject

java.lang.Object
  |
  +--org.mozilla.javascript.ScriptableObject

Direct Known Subclasses:: org.mozilla.javascript.NativeFunction

public abstract class ScriptableObject
extends java.lang.Object
implements Scriptable

This is the default implementation of the Scriptable interface. This class provides convenient default behavior that makes it easier to define host objects.

Various properties and methods of JavaScript objects can be conveniently defined using methods of ScriptableObject.

Classes extending ScriptableObject must define the getClassName method.

Author:: Norris Boyd
See Also:: Scriptable

Field Summary
`static int`	`DONTENUM` Property attribute indicating property is not enumerated.
`static int`	`EMPTY` The empty property attribute.
`protected Scriptable`	`parent` The parent scope of this object.
`static int`	`PERMANENT` Property attribute indicating property cannot be deleted.
`protected Scriptable`	`prototype` The prototype of this object.
`static int`	`READONLY` Property attribute indicating assignment to this property is ignored.

Constructor Summary
`ScriptableObject()`

Method Summary
`static void`	`defineClass(Scriptable scope, java.lang.Class clazz)` Defines JavaScript objects from a Java class.
`static void`	`defineClass(Scriptable scope, java.lang.Class clazz, boolean sealed)` Defines JavaScript objects from a Java class, optionally allowing sealing.
`void`	`defineFunctionProperties(java.lang.String[] names, java.lang.Class clazz, int attributes)` Search for names in a class, adding the resulting methods as properties.
`void`	`defineProperty(java.lang.String propertyName, java.lang.Class clazz, int attributes)` Define a JavaScript property with getter and setter side effects.
`void`	`defineProperty(java.lang.String propertyName, java.lang.Object value, int attributes)` Define a JavaScript property.
`void`	`defineProperty(java.lang.String propertyName, java.lang.Object delegateTo, java.lang.reflect.Method getter, java.lang.reflect.Method setter, int attributes)` Define a JavaScript property.
`void`	`delete(int index)` Removes the indexed property from the object.
`void`	`delete(java.lang.String name)` Removes a named property from the object.
`java.lang.Object`	`get(int index, Scriptable start)` Returns the value of the indexed property or NOT_FOUND.
`java.lang.Object`	`get(java.lang.String name, Scriptable start)` Returns the value of the named property or NOT_FOUND.
`java.lang.Object[]`	`getAllIds()` Returns an array of ids for the properties of the object.
`int`	`getAttributes(int index, Scriptable start)` Get the attributes of an indexed property.
`int`	`getAttributes(java.lang.String name, Scriptable start)` Get the attributes of a named property.
`abstract java.lang.String`	`getClassName()` Return the name of the class.
`static Scriptable`	`getClassPrototype(Scriptable scope, java.lang.String className)` Get the prototype for the named class.
`java.lang.Object`	`getDefaultValue(java.lang.Class typeHint)` Implements the [[DefaultValue]] internal method.
`static Scriptable`	`getFunctionPrototype(Scriptable scope)` Get the Function.prototype property.
`java.lang.Object[]`	`getIds()` Returns an array of ids for the properties of the object.
`static Scriptable`	`getObjectPrototype(Scriptable scope)` Get the Object.prototype property.
`Scriptable`	`getParentScope()` Returns the parent (enclosing) scope of the object.
`Scriptable`	`getPrototype()` Returns the prototype of the object.
`static Scriptable`	`getTopLevelScope(Scriptable obj)` Get the global scope.
`boolean`	`has(int index, Scriptable start)` Returns true if the property index is defined.
`boolean`	`has(java.lang.String name, Scriptable start)` Returns true if the named property is defined.
`boolean`	`hasInstance(Scriptable instance)` Implements the instanceof operator.
`boolean`	`isSealed()` Return true if this object is sealed.
`void`	`put(int index, Scriptable start, java.lang.Object value)` Sets the value of the indexed property, creating it if need be.
`void`	`put(java.lang.String name, Scriptable start, java.lang.Object value)` Sets the value of the named property, creating it if need be.
`void`	`sealObject()` Seal this object.
`void`	`setAttributes(int index, Scriptable start, int attributes)` Set the attributes of an indexed property.
`void`	`setAttributes(java.lang.String name, Scriptable start, int attributes)` Set the attributes of a named property.
`void`	`setParentScope(Scriptable m)` Sets the parent (enclosing) scope of the object.
`void`	`setPrototype(Scriptable m)` Sets the prototype of the object.

Methods inherited from class java.lang.Object

clone, 
equals, 
finalize, 
getClass, 
hashCode, 
notify, 
notifyAll, 
toString, 
wait, 
wait, 
wait

Field Detail

EMPTY

public static final int EMPTY

The empty property attribute. Used by getAttributes() and setAttributes().

See Also:: getAttributes(java.lang.String, org.mozilla.javascript.Scriptable), setAttributes(java.lang.String, org.mozilla.javascript.Scriptable, int)

READONLY

public static final int READONLY

Property attribute indicating assignment to this property is ignored.

See Also:: put(java.lang.String, org.mozilla.javascript.Scriptable, java.lang.Object), getAttributes(java.lang.String, org.mozilla.javascript.Scriptable), setAttributes(java.lang.String, org.mozilla.javascript.Scriptable, int)

DONTENUM

public static final int DONTENUM

Property attribute indicating property is not enumerated. Only enumerated properties will be returned by getIds().

See Also:: getIds(), getAttributes(java.lang.String, org.mozilla.javascript.Scriptable), setAttributes(java.lang.String, org.mozilla.javascript.Scriptable, int)

PERMANENT

public static final int PERMANENT

Property attribute indicating property cannot be deleted.

See Also:: delete(java.lang.String), getAttributes(java.lang.String, org.mozilla.javascript.Scriptable), setAttributes(java.lang.String, org.mozilla.javascript.Scriptable, int)

prototype

protected Scriptable prototype

The prototype of this object.

parent

protected Scriptable parent

The parent scope of this object.

Constructor Detail

ScriptableObject

public ScriptableObject()

Method Detail

getClassName

public abstract java.lang.String getClassName()

Return the name of the class. This is typically the same name as the constructor. Classes extending ScriptableObject must implement this abstract method.

Specified by:: getClassName in interface Scriptable

has

public boolean has(java.lang.String name,
                   Scriptable start)

Returns true if the named property is defined.

Specified by:: has in interface Scriptable
Parameters:: name - the name of the property; start - the object in which the lookup began
Returns:: true if and only if the property was found in the object

has

public boolean has(int index,
                   Scriptable start)

Returns true if the property index is defined.

Specified by:: has in interface Scriptable
Parameters:: index - the numeric index for the property; start - the object in which the lookup began
Returns:: true if and only if the property was found in the object

get

public java.lang.Object get(java.lang.String name,
                            Scriptable start)

Returns the value of the named property or NOT_FOUND. If the property was created using defineProperty, the appropriate getter method is called.

Specified by:: get in interface Scriptable
Parameters:: name - the name of the property; start - the object in which the lookup began
Returns:: the value of the property (may be null), or NOT_FOUND

get

public java.lang.Object get(int index,
                            Scriptable start)

Returns the value of the indexed property or NOT_FOUND.

Specified by:: get in interface Scriptable
Parameters:: index - the numeric index for the property; start - the object in which the lookup began
Returns:: the value of the property (may be null), or NOT_FOUND

put

public void put(java.lang.String name,
                Scriptable start,
                java.lang.Object value)

Sets the value of the named property, creating it if need be. If the property was created using defineProperty, the appropriate setter method is called.

If the property's attributes include READONLY, no action is taken. This method will actually set the property in the start object.

Specified by:: put in interface Scriptable
Parameters:: name - the name of the property; start - the object whose property is being set; value - value to set the property to

put

public void put(int index,
                Scriptable start,
                java.lang.Object value)

Sets the value of the indexed property, creating it if need be.

Specified by:: put in interface Scriptable
Parameters:: index - the numeric index for the property; start - the object whose property is being set; value - value to set the property to

delete

public void delete(java.lang.String name)

Removes a named property from the object. If the property is not found, or it has the PERMANENT attribute, no action is taken.

Specified by:: delete in interface Scriptable
Parameters:: name - the name of the property

delete

public void delete(int index)

Removes the indexed property from the object. If the property is not found, or it has the PERMANENT attribute, no action is taken.

Specified by:: delete in interface Scriptable
Parameters:: index - the numeric index for the property

getAttributes

public int getAttributes(java.lang.String name,
                         Scriptable start)
                  throws PropertyException

Get the attributes of a named property. The property is specified by name as defined for has.

Parameters:: name - the identifier for the property; start - the object in which the lookup began
Returns:: the bitset of attributes
Throws:: PropertyException - if the named property is not found
See Also:: has(java.lang.String, org.mozilla.javascript.Scriptable), READONLY, DONTENUM, PERMANENT, EMPTY

getAttributes

public int getAttributes(int index,
                         Scriptable start)
                  throws PropertyException

Get the attributes of an indexed property.

Parameters:: index - the numeric index for the property; start - the object in which the lookup began
Returns:: the bitset of attributes
Throws:: PropertyException - if the indexed property is not found
See Also:: has(java.lang.String, org.mozilla.javascript.Scriptable), READONLY, DONTENUM, PERMANENT, EMPTY

setAttributes

public void setAttributes(java.lang.String name,
                          Scriptable start,
                          int attributes)
                   throws PropertyException

Set the attributes of a named property. The property is specified by name as defined for has.

The possible attributes are READONLY, DONTENUM, and PERMANENT. Combinations of attributes are expressed by the bitwise OR of attributes. EMPTY is the state of no attributes set. Any unused bits are reserved for future use.

Parameters:: name - the name of the property; start - the object in which the lookup began; attributes - the bitset of attributes
Throws:: PropertyException - if the named property is not found
See Also:: Scriptable.has(java.lang.String, org.mozilla.javascript.Scriptable), READONLY, DONTENUM, PERMANENT, EMPTY

setAttributes

public void setAttributes(int index,
                          Scriptable start,
                          int attributes)
                   throws PropertyException

Set the attributes of an indexed property.

Parameters:: index - the numeric index for the property; start - the object in which the lookup began; attributes - the bitset of attributes
Throws:: PropertyException - if the indexed property is not found
See Also:: Scriptable.has(java.lang.String, org.mozilla.javascript.Scriptable), READONLY, DONTENUM, PERMANENT, EMPTY

getPrototype

public Scriptable getPrototype()

Returns the prototype of the object.

Specified by:: getPrototype in interface Scriptable

setPrototype

public void setPrototype(Scriptable m)

Sets the prototype of the object.

Specified by:: setPrototype in interface Scriptable

getParentScope

public Scriptable getParentScope()

Returns the parent (enclosing) scope of the object.

Specified by:: getParentScope in interface Scriptable

setParentScope

public void setParentScope(Scriptable m)

Sets the parent (enclosing) scope of the object.

Specified by:: setParentScope in interface Scriptable

getIds

public java.lang.Object[] getIds()

Returns an array of ids for the properties of the object.

Any properties with the attribute DONTENUM are not listed.

Specified by:: getIds in interface Scriptable
Returns:: an array of java.lang.Objects with an entry for every listed property. Properties accessed via an integer index will have a corresponding Integer entry in the returned array. Properties accessed by a String will have a String entry in the returned array.

getAllIds

public java.lang.Object[] getAllIds()

Returns an array of ids for the properties of the object.

All properties, even those with attribute DONTENUM, are listed.

Returns:: an array of java.lang.Objects with an entry for every listed property. Properties accessed via an integer index will have a corresponding Integer entry in the returned array. Properties accessed by a String will have a String entry in the returned array.

getDefaultValue

public java.lang.Object getDefaultValue(java.lang.Class typeHint)

Implements the [[DefaultValue]] internal method.

Note that the toPrimitive conversion is a no-op for every type other than Object, for which [[DefaultValue]] is called. See ECMA 9.1.

A hint of null means "no hint".

Specified by:: getDefaultValue in interface Scriptable
Parameters:: typeHint - the type hint
Returns:: the default value for the object See ECMA 8.6.2.6.

hasInstance

public boolean hasInstance(Scriptable instance)

Implements the instanceof operator.

This operator has been proposed to ECMA.

Specified by:: hasInstance in interface Scriptable
Parameters:: instance - The value that appeared on the LHS of the instanceof operator
Returns:: true if "this" appears in value's prototype chain

defineClass

public static void defineClass(Scriptable scope,
                               java.lang.Class clazz)
                        throws java.lang.IllegalAccessException,
                               java.lang.InstantiationException,
                               java.lang.reflect.InvocationTargetException,
                               ClassDefinitionException,
                               PropertyException

Defines JavaScript objects from a Java class. If the given class has a method

 static void init(Scriptable scope);

then it is invoked and no further initialization is done and the result of the invocation will be returned.

However, if no such a method is found, then the class's constructors and methods are used to initialize a class in the following manner.

First, the zero-parameter constructor of the class is called to create the prototypical instance. If no such constructor exists, a ClassDefinitionException is thrown.

Next, all methods are scanned. If any method begins with a special prefix, then only methods with special prefixes are considered for defining functions and properties. These special prefixes are

js_ for a JavaScript property or function, as determined by the name of the method
jsFunction_ for a JavaScript function
jsStaticFunction_ for a JavaScript function that is a property of the constructor
jsProperty_ for a JavaScript property

If no methods begin with any of these prefixes, all methods are added as JavaScript functions or properties except those with names matching the names of methods in org.mozilla.javascript.Function or any of its supertypes. This means that call, which is a method in Function, and get, which is a method in Scriptable (which Function extends), are both excluded from defining JavaScript methods.

If after removing any prefixes, a method's name matches the name of the class (determined by calling getClassName() on the prototypical instance), it is considered to define the JavaScript constructor.

If the method's name begins with "get" or "set" after any prefix other than "jsFunction_" is removed, the method is considered to define a property. Accesses to the defined property will result in calls to these getter and setter methods. If no setter is defined, the property is defined as READONLY.

Otherwise, a JavaScript function is created that will call the given method. This function is then added as a property of the prototypical instance. So if a JavaScript function beginning with "get" or "set" is desired, it must be prefixed with "jsFunction_" to distinquish it from a method defining a property.

If no method is found that can serve as constructor, a Java constructor will be selected to serve as the JavaScript constructor in the following manner. If the class has only one Java constructor, that constructor is used to define the JavaScript constructor. If the the class has two constructors, one must be the zero-argument constructor (otherwise an ClassDefinitionException would have already been thrown when the prototypical instance was to be created). In this case the Java constructor with one or more parameters will be used to define the JavaScript constructor. If the class has three or more constructors, an ClassDefinitionException will be thrown.

Finally, if there is a method

 static void finishInit(Scriptable scope, FunctionObject constructor,
                        Scriptable prototype)

it will be called to finish any initialization. The scope argument will be passed, along with the newly created constructor and the newly created prototype.

Parameters:: scope - The scope in which to define the constructor; clazz - The Java class to use to define the JavaScript objects and properties
Throws:: java.lang.IllegalAccessException - if access is not available to a reflected class member; java.lang.InstantiationException - if unable to instantiate the named class; java.lang.reflect.InvocationTargetException - if an exception is thrown during execution of methods of the named class; ClassDefinitionException - if an appropriate constructor cannot be found to create the prototypical instance; PropertyException - if getter and setter methods do not conform to the requirements of the defineProperty method
See Also:: Function, FunctionObject, READONLY, defineProperty(java.lang.String, java.lang.Object, int)

defineClass

public static void defineClass(Scriptable scope,
                               java.lang.Class clazz,
                               boolean sealed)
                        throws java.lang.IllegalAccessException,
                               java.lang.InstantiationException,
                               java.lang.reflect.InvocationTargetException,
                               ClassDefinitionException,
                               PropertyException

Defines JavaScript objects from a Java class, optionally allowing sealing. Similar to defineClass(Scriptable scope, Class clazz) except that sealing is allowed. An object that is sealed cannot have properties added or removed. Note that sealing is not allowed in the current ECMA/ISO language specification, but is likely for the next version.

Parameters:: scope - The scope in which to define the constructor; clazz - The Java class to use to define the JavaScript objects and properties; sealed - whether or not to create sealed standard objects that cannot be modified.
Throws:: java.lang.IllegalAccessException - if access is not available to a reflected class member; java.lang.InstantiationException - if unable to instantiate the named class; java.lang.reflect.InvocationTargetException - if an exception is thrown during execution of methods of the named class; ClassDefinitionException - if an appropriate constructor cannot be found to create the prototypical instance; PropertyException - if getter and setter methods do not conform to the requirements of the defineProperty method
Since:: 1.4R3

defineProperty

public void defineProperty(java.lang.String propertyName,
                           java.lang.Object value,
                           int attributes)

Define a JavaScript property. Creates the property with an initial value and sets its attributes.

Parameters:: propertyName - the name of the property to define.; value - the initial value of the property; attributes - the attributes of the JavaScript property
See Also:: Scriptable.put(java.lang.String, org.mozilla.javascript.Scriptable, java.lang.Object)

defineProperty

public void defineProperty(java.lang.String propertyName,
                           java.lang.Class clazz,
                           int attributes)
                    throws PropertyException

Define a JavaScript property with getter and setter side effects. If the setter is not found, the attribute READONLY is added to the given attributes.

The getter must be a method with zero parameters, and the setter, if found, must be a method with one parameter.

Parameters:: propertyName - the name of the property to define. This name also affects the name of the setter and getter to search for. If the propertyId is "foo", then clazz will be searched for "getFoo" and "setFoo" methods.; clazz - the Java class to search for the getter and setter; attributes - the attributes of the JavaScript property
Throws:: PropertyException - if multiple methods are found for the getter or setter, or if the getter or setter do not conform to the forms described in defineProperty(String, Object, Method, Method, int)
See Also:: Scriptable.put(java.lang.String, org.mozilla.javascript.Scriptable, java.lang.Object)

defineProperty

public void defineProperty(java.lang.String propertyName,
                           java.lang.Object delegateTo,
                           java.lang.reflect.Method getter,
                           java.lang.reflect.Method setter,
                           int attributes)
                    throws PropertyException

Define a JavaScript property. Use this method only if you wish to define getters and setters for a given property in a ScriptableObject. To create a property without special getter or setter side effects, use defineProperty(String,int). If setter is null, the attribute READONLY is added to the given attributes.

Several forms of getters or setters are allowed. The first are nonstatic methods of the class referred to by 'this':

 Object getFoo();
 void setFoo(Object value);

Next are static methods that may be of any class; the object whose property is being accessed is passed in as an extra argument:

 static Object getFoo(ScriptableObject obj);
 static void setFoo(ScriptableObject obj, Object value);

Finally, it is possible to delegate to another object entirely using the delegateTo parameter. In this case the methods are nonstatic methods of the class delegated to, and the object whose property is being accessed is passed in as an extra argument:

 Object getFoo(ScriptableObject obj);
 void setFoo(ScriptableObject obj, Object value);

Parameters:: propertyName - the name of the property to define.; delegateTo - an object to call the getter and setter methods on, or null, depending on the form used above.; getter - the method to invoke to get the value of the property; setter - the method to invoke to set the value of the property; attributes - the attributes of the JavaScript property
Throws:: PropertyException - if the getter or setter do not conform to the forms specified above

defineFunctionProperties

public void defineFunctionProperties(java.lang.String[] names,
                                     java.lang.Class clazz,
                                     int attributes)
                              throws PropertyException

Search for names in a class, adding the resulting methods as properties.

Uses reflection to find the methods of the given names. Then FunctionObjects are constructed from the methods found, and are added to this object as properties with the given names.

Parameters:: names - the names of the Methods to add as function properties; clazz - the class to search for the Methods; attributes - the attributes of the new properties
Throws:: PropertyException - if any of the names has no corresponding method or more than one corresponding method in the class
See Also:: FunctionObject

getObjectPrototype

public static Scriptable getObjectPrototype(Scriptable scope)

Get the Object.prototype property. See ECMA 15.2.4.

getFunctionPrototype

public static Scriptable getFunctionPrototype(Scriptable scope)

Get the Function.prototype property. See ECMA 15.3.4.

getClassPrototype

public static Scriptable getClassPrototype(Scriptable scope,
                                           java.lang.String className)

Get the prototype for the named class. For example, getClassPrototype(s, "Date") will first walk up the parent chain to find the outermost scope, then will search that scope for the Date constructor, and then will return Date.prototype. If any of the lookups fail, or the prototype is not a JavaScript object, then null will be returned.

Parameters:: scope - an object in the scope chain; className - the name of the constructor
Returns:: the prototype for the named class, or null if it cannot be found.

getTopLevelScope

public static Scriptable getTopLevelScope(Scriptable obj)

Get the global scope.

Walks the parent scope chain to find an object with a null parent scope (the global object).

Parameters:: obj - a JavaScript object
Returns:: the corresponding global scope

sealObject

public void sealObject()

Seal this object. A sealed object may not have properties added or removed. Once an object is sealed it may not be unsealed.

Since:: 1.4R3

isSealed

public boolean isSealed()

Return true if this object is sealed. It is an error to attempt to add or remove properties to a sealed object.

Returns:: true if sealed, false otherwise.
Since:: 1.4R3

Overview

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SUMMARY: INNER | FIELD | CONSTR | METHOD

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org.mozilla.javascript Class ScriptableObject

EMPTY

READONLY

DONTENUM

PERMANENT

prototype

parent

ScriptableObject

getClassName

has

has

get

get

put

put

delete

delete

getAttributes

getAttributes

setAttributes

setAttributes

getPrototype

setPrototype

getParentScope

setParentScope

getIds

getAllIds

getDefaultValue

hasInstance

defineClass

defineClass

defineProperty

defineProperty

defineProperty

defineFunctionProperties

getObjectPrototype

getFunctionPrototype

getClassPrototype

getTopLevelScope

sealObject

isSealed

org.mozilla.javascript
Class ScriptableObject