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package javax.script;
import java.util.List;
import java.io.Writer;
import java.io.Reader;

The interface whose implementing classes are used to connect Script Engines
with objects, such as scoped Bindings, in hosting applications.  Each scope is a set
of named attributes whose values can be set and retrieved using the
ScriptContext methods. ScriptContexts also expose Readers and Writers
that can be used by the ScriptEngines for input and output.
Author:
Mike Grogan
Since:
1.6/**
 * The interface whose implementing classes are used to connect Script Engines
 * with objects, such as scoped Bindings, in hosting applications.  Each scope is a set
 * of named attributes whose values can be set and retrieved using the
 * <code>ScriptContext</code> methods. ScriptContexts also expose Readers and Writers
 * that can be used by the ScriptEngines for input and output.
 *
 * @author Mike Grogan
 * @since 1.6
 */
public interface ScriptContext {


    
EngineScope attributes are visible during the lifetime of a single
ScriptEngine and a set of attributes is maintained for each
engine.
/**
     * EngineScope attributes are visible during the lifetime of a single
     * <code>ScriptEngine</code> and a set of attributes is maintained for each
     * engine.
     */
    public static final int ENGINE_SCOPE = 100;

    
GlobalScope attributes are visible to all engines created by same ScriptEngineFactory.
/**
     * GlobalScope attributes are visible to all engines created by same ScriptEngineFactory.
     */
    public static final int GLOBAL_SCOPE = 200;


    
Associates a Bindings instance with a particular scope in this
ScriptContext.  Calls to the getAttribute and
setAttribute methods must map to the get and
put methods of the Bindings for the specified scope.
Params:
bindings – The Bindings to associate with the given scope
scope – The scope
Throws:
IllegalArgumentException – If no Bindings is defined for the
specified scope value in ScriptContexts of this type.
NullPointerException – if value of scope is ENGINE_SCOPE and
the specified Bindings is null./**
     * Associates a <code>Bindings</code> instance with a particular scope in this
     * <code>ScriptContext</code>.  Calls to the <code>getAttribute</code> and
     * <code>setAttribute</code> methods must map to the <code>get</code> and
     * <code>put</code> methods of the <code>Bindings</code> for the specified scope.
     *
     * @param  bindings The <code>Bindings</code> to associate with the given scope
     * @param scope The scope
     *
     * @throws IllegalArgumentException If no <code>Bindings</code> is defined for the
     * specified scope value in ScriptContexts of this type.
     * @throws NullPointerException if value of scope is <code>ENGINE_SCOPE</code> and
     * the specified <code>Bindings</code> is null.
     *
     */
    public void setBindings(Bindings bindings, int scope);

    
Gets the Bindings  associated with the given scope in this
ScriptContext.
Params:
scope – The scope
Throws:
IllegalArgumentException – If no Bindings is defined for the
specified scope value in ScriptContext of this type.
Returns:
The associated Bindings.  Returns null if it has not
been set./**
     * Gets the <code>Bindings</code>  associated with the given scope in this
     * <code>ScriptContext</code>.
     *
     * @return The associated <code>Bindings</code>.  Returns <code>null</code> if it has not
     * been set.
     *
     * @param scope The scope
     * @throws IllegalArgumentException If no <code>Bindings</code> is defined for the
     * specified scope value in <code>ScriptContext</code> of this type.
     */
    public Bindings getBindings(int scope);

    
Sets the value of an attribute in a given scope.
Params:
name – The name of the attribute to set
value – The value of the attribute
scope – The scope in which to set the attribute
Throws:
IllegalArgumentException – 
        if the name is empty or if the scope is invalid.
NullPointerException – if the name is null./**
     * Sets the value of an attribute in a given scope.
     *
     * @param name The name of the attribute to set
     * @param value The value of the attribute
     * @param scope The scope in which to set the attribute
     *
     * @throws IllegalArgumentException
     *         if the name is empty or if the scope is invalid.
     * @throws NullPointerException if the name is null.
     */
    public void setAttribute(String name, Object value, int scope);

    
Gets the value of an attribute in a given scope.
Params:
name – The name of the attribute to retrieve.
scope – The scope in which to retrieve the attribute.
Throws:
IllegalArgumentException – 
        if the name is empty or if the value of scope is invalid.
NullPointerException – if the name is null.
Returns:
The value of the attribute. Returns null is the name
does not exist in the given scope./**
     * Gets the value of an attribute in a given scope.
     *
     * @param name The name of the attribute to retrieve.
     * @param scope The scope in which to retrieve the attribute.
     * @return The value of the attribute. Returns <code>null</code> is the name
     * does not exist in the given scope.
     *
     * @throws IllegalArgumentException
     *         if the name is empty or if the value of scope is invalid.
     * @throws NullPointerException if the name is null.
     */
    public Object getAttribute(String name, int scope);

    
Remove an attribute in a given scope.
Params:
name – The name of the attribute to remove
scope – The scope in which to remove the attribute
Throws:
IllegalArgumentException – 
        if the name is empty or if the scope is invalid.
NullPointerException – if the name is null.
Returns:
The removed value./**
     * Remove an attribute in a given scope.
     *
     * @param name The name of the attribute to remove
     * @param scope The scope in which to remove the attribute
     *
     * @return The removed value.
     * @throws IllegalArgumentException
     *         if the name is empty or if the scope is invalid.
     * @throws NullPointerException if the name is null.
     */
    public Object removeAttribute(String name, int scope);

    
Retrieves the value of the attribute with the given name in
the scope occurring earliest in the search order.  The order
is determined by the numeric value of the scope parameter (lowest
scope values first.)
Params:
name – The name of the the attribute to retrieve.
Throws:
NullPointerException – if the name is null.
IllegalArgumentException – if the name is empty.
Returns:
The value of the attribute in the lowest scope for
which an attribute with the given name is defined.  Returns
null if no attribute with the name exists in any scope./**
     * Retrieves the value of the attribute with the given name in
     * the scope occurring earliest in the search order.  The order
     * is determined by the numeric value of the scope parameter (lowest
     * scope values first.)
     *
     * @param name The name of the the attribute to retrieve.
     * @return The value of the attribute in the lowest scope for
     * which an attribute with the given name is defined.  Returns
     * null if no attribute with the name exists in any scope.
     * @throws NullPointerException if the name is null.
     * @throws IllegalArgumentException if the name is empty.
     */
    public Object getAttribute(String name);


    
Get the lowest scope in which an attribute is defined.
Params:
name – Name of the attribute
.
Throws:
NullPointerException – if name is null.
IllegalArgumentException – if name is empty.
Returns:
The lowest scope.  Returns -1 if no attribute with the given
name is defined in any scope./**
     * Get the lowest scope in which an attribute is defined.
     * @param name Name of the attribute
     * .
     * @return The lowest scope.  Returns -1 if no attribute with the given
     * name is defined in any scope.
     * @throws NullPointerException if name is null.
     * @throws IllegalArgumentException if name is empty.
     */
    public int getAttributesScope(String name);

    
Returns the Writer for scripts to use when displaying output.
Returns:
The Writer./**
     * Returns the <code>Writer</code> for scripts to use when displaying output.
     *
     * @return The <code>Writer</code>.
     */
    public Writer getWriter();


    
Returns the Writer used to display error output.
Returns:
The Writer/**
     * Returns the <code>Writer</code> used to display error output.
     *
     * @return The <code>Writer</code>
     */
    public Writer getErrorWriter();

    
Sets the Writer for scripts to use when displaying output.
Params:
writer – The new Writer./**
     * Sets the <code>Writer</code> for scripts to use when displaying output.
     *
     * @param writer The new <code>Writer</code>.
     */
    public void setWriter(Writer writer);


    
Sets the Writer used to display error output.
Params:
writer – The Writer./**
     * Sets the <code>Writer</code> used to display error output.
     *
     * @param writer The <code>Writer</code>.
     */
    public void setErrorWriter(Writer writer);

    
Returns a Reader to be used by the script to read
input.
Returns:
The Reader./**
     * Returns a <code>Reader</code> to be used by the script to read
     * input.
     *
     * @return The <code>Reader</code>.
     */
    public Reader getReader();


    
Sets the Reader for scripts to read input
.
Params:
reader – The new Reader./**
     * Sets the <code>Reader</code> for scripts to read input
     * .
     * @param reader The new <code>Reader</code>.
     */
    public void setReader(Reader reader);

    
Returns immutable List of all the valid values for
scope in the ScriptContext.
Returns:
list of scope values/**
     * Returns immutable <code>List</code> of all the valid values for
     * scope in the ScriptContext.
     *
     * @return list of scope values
     */
    public List<Integer> getScopes();
}