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  /* -*- Mode: java; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
   *
   * This Source Code Form is subject to the terms of the Mozilla Public
   * License, v. 2.0. If a copy of the MPL was not distributed with this
   * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
  
  // API class
  
  package org.mozilla.javascript;

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.

Author(s):
Norris Boyd
Nick Thompson
Brendan Eich
See also:
ScriptableObject
 
 
 public interface Scriptable {

    
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.

 
     public String getClassName();

    
Value returned from get if the property is not found.
 
     public static final Object NOT_FOUND = .;

    
Get a named property from the object. 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.mozilla.javascript.Scriptable objects
  • null
  • The value returned by Context.getUndefinedValue()
  • NOT_FOUND

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
See also:
Context.getUndefinedValue()
 
     public Object get(String nameScriptable start);

    
Get a property from the object selected by an integral index. Identical to get(String, Scriptable) except that an integral index is used to select the property.

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
See also:
get(java.lang.String,org.mozilla.javascript.Scriptable)
 
     public Object get(int indexScriptable start);

    
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
start the object in which the lookup began
Returns:
true if and only if the named property is found in the object
See also:
get(java.lang.String,org.mozilla.javascript.Scriptable)
ScriptableObject.getProperty(org.mozilla.javascript.Scriptable,java.lang.String)
    public boolean has(String nameScriptable start);

    
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
start the object in which the lookup began
Returns:
true if and only if the indexed property is found in the object
See also:
get(int,org.mozilla.javascript.Scriptable)
ScriptableObject.getProperty(org.mozilla.javascript.Scriptable,int)
    public boolean has(int indexScriptable start);

    
Sets a named property in this object.

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

The possible values that may be passed in are as defined for get. A class that implements this method may choose to ignore calls to set certain properties, in which case those properties are effectively read-only.

For properties defined in a prototype chain, use putProperty in ScriptableObject.

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.mozilla.javascript.Scriptable objects
  • null
  • The value returned by Context.getUndefinedValue()

Arbitrary Java objects may be wrapped in a Scriptable by first calling Context.toObject. This allows the property of a JavaScript object to contain an arbitrary Java object as a value.

Note that has will be called by the runtime first before set is called to determine in which object the property is defined. Note that this method is not expected to traverse the prototype chain, which is different from the ECMA [[Put]] operation.

    public void put(String nameScriptable startObject value);

    
Sets an indexed property in this object.

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

Identical to put(String, Scriptable, Object) except that an integral index is used to select the property.

    public void put(int indexScriptable startObject value);

    
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, see deleteProperty in ScriptableObject.

    public void delete(String name);

    
Removes a property from this object. The property is specified by an integral index as defined for get.

To delete properties defined in a prototype chain, see deleteProperty in ScriptableObject. Identical to delete(String) except that an integral index is used to select the property.

    public void delete(int index);

    
Get the prototype of the object.

Returns:
the prototype
    public Scriptable getPrototype();

    
Set the prototype of the object.

Parameters:
prototype the prototype to set
    public void setPrototype(Scriptable prototype);

    
Get the parent scope of the object.

Returns:
the parent scope
    public Scriptable getParentScope();

    
Set the parent scope of the object.

Parameters:
parent the parent scope to set
    public void setParentScope(Scriptable parent);

    
Get an array of property ids. Not all property ids need be returned. Those properties whose ids are not returned are considered non-enumerable.

Returns:
an array of Objects. Each entry in the array is either a java.lang.String or a java.lang.Number
    public Object[] getIds();

    
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
    public Object getDefaultValue(Class<?> hint);

    
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
    public boolean hasInstance(Scriptable instance);
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