org.apache.bsf.debug.jsdi

Interface JsObject

All Superinterfaces:
Remote
Known Subinterfaces:
JsCode, JsFunction, JsScript
Known Implementing Classes:
JsCodeStub, JsObjectStub, JsObjectStub

public interface JsObject
extends Remote

This is interface that all objects in JavaScript must implement. The interface provides for the management of properties and for performing conversions.

Host system implementors may find it easier to extend the ScriptableObject class rather than implementing Scriptable when writing host objects.

There are many static methods defined in ScriptableObject that perform the multiple calls to the Scriptable interface needed in order to manipulate properties in prototype chains.

Field Summary

static int
DONTDELETE
Property attribute indicating property cannot be deleted.
static int
DONTENUM
Property attribute indicating property is not enumerated.
static int
EMPTY
The empty property attribute.
static int
INTERNAL
Property attribute indicating property cannot be deleted.
static int
READONLY
Property attribute indicating assignment to this property is ignored.

Method Summary

void
define(String propertyName, Object value, int attributes)
The value can be any of the following type: java.lang.Boolean java.lang.Number java.lang.String org.apache.bsf.debug.jsdi.JsObject
void
delete(String name)
Removes a property from this object.
void
delete(int index)
Removes a property from this object.
Object
get(String name)
Get a named property from the object.
Object
get(int index)
String
getClassName()
Get the name of the set of objects implemented by this Java class.
Object
getDefaultValue(Class hint)
Get the default value of the object with a given hint.
Object[]
getIds(boolean all)
Returns an array of property ids defined on this object.
JsObject
getPrototype()
Get the prototype of the object.
JsObject
getScope()
The scope is for supporting two things.
boolean
has(String name)
Indicates whether or not a named property is defined in an object.
boolean
has(int index)
Indicates whether or not an indexed property is defined in an object.
boolean
hasInstance(JsObject instance)
The instanceof operator.
boolean
isFunction()
boolean
isScript()
void
put(String name, Object value)
Sets a named property in this object.
void
put(int index, Object value)
Sets an indexed property in this object.
void
setPrototype(JsObject prototype)
Set the prototype of the object.
void
setScope(JsObject scope)
Set the prototype of the object.

Field Details

DONTDELETE

public static final int DONTDELETE
Property attribute indicating property cannot be deleted.
Field Value:
4
See Also:
org.mozilla.javascript.ScriptableObject.delete, org.mozilla.javascript.ScriptableObject.getAttributes, org.mozilla.javascript.ScriptableObject.setAttributes

DONTENUM

public static final int DONTENUM
Property attribute indicating property is not enumerated. Only enumerated properties will be returned by getIds().
Field Value:
2
See Also:
org.mozilla.javascript.ScriptableObject.getIds, org.mozilla.javascript.ScriptableObject.getAttributes, org.mozilla.javascript.ScriptableObject.setAttributes

EMPTY

public static final int EMPTY
The empty property attribute. Used by getAttributes() and setAttributes().
Field Value:
0
See Also:
org.mozilla.javascript.ScriptableObject.getAttributes, org.mozilla.javascript.ScriptableObject.setAttributes

INTERNAL

public static final int INTERNAL
Property attribute indicating property cannot be deleted.
Field Value:
5
See Also:
org.mozilla.javascript.ScriptableObject.delete, org.mozilla.javascript.ScriptableObject.getAttributes, org.mozilla.javascript.ScriptableObject.setAttributes

READONLY

public static final int READONLY
Property attribute indicating assignment to this property is ignored.
Field Value:
1
See Also:
org.mozilla.javascript.ScriptableObject.put, org.mozilla.javascript.ScriptableObject.getAttributes, org.mozilla.javascript.ScriptableObject.setAttributes

Method Details

define

public void define(String propertyName,
                   Object value,
                   int attributes)
            throws RemoteException
The value can be any of the following type: java.lang.Boolean java.lang.Number java.lang.String org.apache.bsf.debug.jsdi.JsObject

delete

public void delete(String name)
            throws RemoteException
Removes a property from this object. This operation corresponds to the ECMA [[Delete]] except that the no result is returned. The runtime will guarantee that this method is called only if the property exists. After this method is called, the runtime will call Scriptable.has to see if the property has been removed in order to determine the boolean result of the delete operator as defined by ECMA 11.4.1.

A property can be made permanent by ignoring calls to remove it.

The property is specified by a String name as defined for get.

To delete properties defined in a prototype chain, first find the owner object of the property and then call deleteProperty on that owner object.

Parameters:
name - the identifier for the property
See Also:
org.mozilla.javascript.Scriptable.get, org.mozilla.javascript.ScriptableObject.deleteProperty

delete

public void delete(int index)
            throws RemoteException
Removes a property from this object. The prototype chain is not walked to find the property. This operation corresponds to the ECMA [[Delete]] except that the no result is returned. The runtime will guarantee that this method is called only if the property exists. After this method is called, the runtime will call Scriptable.has to see if the property has been removed in order to determine the boolean result of the delete operator as defined by ECMA 11.4.1.

A property can be made permanent by ignoring calls to remove it. The property is specified by an integral index as defined for get.

To delete properties defined in a prototype chain, first find the owner object of the property and then call deleteProperty on that owner object. Identical to delete(String) except that an integral index is used to select the property.

Parameters:
index - the numeric index for the property
See Also:
org.mozilla.javascript.Scriptable.get, org.mozilla.javascript.ScriptableObject.deleteProperty

get

public Object get(String name)
            throws RemoteException
Get a named property from the object. Does not walk the prototype chain. Looks property up in this object and returns the associated value if found. Returns NOT_FOUND if not found. Note that this method is not expected to traverse the prototype chain. This is different from the ECMA [[Get]] operation. Depending on the property selector, the runtime will call this method or the form of get that takes an integer:
JavaScript codeJava code
a.b a.get("b", a)
a["foo"] a.get("foo", a)
a[3] a.get(3, a)
a["3"] a.get(3, a)
a[3.0] a.get(3, a)
a["3.0"] a.get("3.0", a)
a[1.1] a.get("1.1", a)
a[-4] a.get(-4, a)

The values that may be returned are limited to the following:

  • java.lang.Boolean objects
  • java.lang.String objects
  • java.lang.Number objects
  • org.apache.bsf.debug.jsdi.JsObject objects
  • null
  • The value returned by Context.getUndefinedValue()
  • NOT_FOUND
Parameters:
name - the name of the property
Returns:
the value of the property (may be null), or NOT_FOUND

get

public Object get(int index)
            throws RemoteException

getClassName

public String getClassName()
            throws RemoteException
Get the name of the set of objects implemented by this Java class. This corresponds to the [[Class]] operation in ECMA and is used by Object.prototype.toString() in ECMA.

See ECMA 8.6.2 and 15.2.4.2.


getDefaultValue

public Object getDefaultValue(Class hint)
            throws RemoteException
Get the default value of the object with a given hint. The hints are String.class for type String, Number.class for type Number, Scriptable.class for type Object, and Boolean.class for type Boolean.

A hint of null means "no hint". See ECMA 8.6.2.6.

Parameters:
hint - the type hint
Returns:
the default value

getIds

public Object[] getIds(boolean all)
            throws RemoteException
Returns an array of property ids defined on this object. The prototype chain is not walked. However, modified properties that were prototype properties will be seen. The parameter indicates to enumerate the "DONTENUM" properties or not.

Returns:
an array of all ids from all object in the prototype chain. If a given id occurs multiple times in the prototype chain, it will occur only once in this list. The elements are limited to: - java.lang.String for the property name if it has one. - java.lang.Integer for properties without a name, it is their index.
Since:
1.5R2

getPrototype

public JsObject getPrototype()
            throws RemoteException
Get the prototype of the object.
Returns:
the prototype

getScope

public JsObject getScope()
            throws RemoteException
The scope is for supporting two things. If the object is a function, the scope is the "execution" scope of the function. It will be used when calling the function to initialize the Context scope. If the object is not a function, the scope is used for the scope chain of execution context.

has

public boolean has(String name)
            throws RemoteException
Indicates whether or not a named property is defined in an object. Does not traverse the prototype chain.

The property is specified by a String name as defined for the get method.

Parameters:
name - the name of the property
Returns:
true if and only if the named property is found in the object
See Also:
org.mozilla.javascript.Scriptable.get, org.mozilla.javascript.ScriptableObject.getProperty

has

public boolean has(int index)
            throws RemoteException
Indicates whether or not an indexed property is defined in an object. Does not traverse the prototype chain.

The property is specified by an integral index as defined for the get method.

Parameters:
index - the numeric index for the property
Returns:
true if and only if the indexed property is found in the object
See Also:
org.mozilla.javascript.Scriptable.get, org.mozilla.javascript.ScriptableObject.getProperty

hasInstance

public boolean hasInstance(JsObject instance)
            throws RemoteException
The instanceof operator.

The JavaScript code "lhs instanceof rhs" causes rhs.hasInstance(lhs) to be called.

The return value is implementation dependent so that embedded host objects can return an appropriate value. See the JS 1.3 language documentation for more detail.

This operator corresponds to the proposed EMCA [[HasInstance]] operator.

Parameters:
instance - The value that appeared on the LHS of the instanceof operator
Returns:
an implementation dependent value

isFunction

public boolean isFunction()
            throws RemoteException

isScript

public boolean isScript()
            throws RemoteException

put

public void put(String name,
                Object value)
            throws RemoteException
Sets a named property in this object.

The property is specified by a string name as defined for get.

Note that if a property a is defined in the prototype p of an object o, then evaluating o.a = 23 will cause set to be called on the prototype p with o as the start parameter. To preserve JavaScript semantics, it is the Scriptable object's responsibility to modify o.

This design allows properties to be defined in prototypes and implemented in terms of getters and setters of Java values without consuming slots in each instance.

The values that may be set are limited to the following:

  • java.lang.Boolean objects
  • java.lang.String objects
  • java.lang.Number objects
  • org.apache.bsf.debug.jsdi.JsObject
  • null
  • The value returned by Context.getUndefinedValue()

IMPORTANT: JAVA OBJECTS. The wrapping is not yet supported.


put

public void put(int index,
                Object value)
            throws RemoteException
Sets an indexed property in this object.

The property is specified by an integral index as defined for get.

Parameters:
index - the numeric index for the property
value - value to set the property to

setPrototype

public void setPrototype(JsObject prototype)
            throws RemoteException
Set the prototype of the object.
Parameters:
prototype - the prototype to set

setScope

public void setScope(JsObject scope)
            throws RemoteException
Set the prototype of the object.
Parameters: