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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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package javax.script;

import java.util.*;
import java.io.*;


Simple implementation of ScriptContext.

Author:Mike Grogan
Since:1.6
/**
 * Simple implementation of ScriptContext.
 *
 * @author Mike Grogan
 * @since 1.6
 */
public class SimpleScriptContext  implements ScriptContext {

    
This is the writer to be used to output from scripts.
By default, a PrintWriter based on System.out
is used. Accessor methods getWriter, setWriter are used to manage
this field.

See Also:
/**
     * This is the writer to be used to output from scripts.
     * By default, a <code>PrintWriter</code> based on <code>System.out</code>
     * is used. Accessor methods getWriter, setWriter are used to manage
     * this field.
     * @see java.lang.System#out
     * @see java.io.PrintWriter
     */
    protected Writer writer;

    
This is the writer to be used to output errors from scripts.
By default, a PrintWriter based on System.err is
used. Accessor methods getErrorWriter, setErrorWriter are used to manage
this field.

See Also:
/**
     * This is the writer to be used to output errors from scripts.
     * By default, a <code>PrintWriter</code> based on <code>System.err</code> is
     * used. Accessor methods getErrorWriter, setErrorWriter are used to manage
     * this field.
     * @see java.lang.System#err
     * @see java.io.PrintWriter
     */
    protected Writer errorWriter;

    
This is the reader to be used for input from scripts.
By default, a InputStreamReader based on System.in
is used and default charset is used by this reader. Accessor methods
getReader, setReader are used to manage this field.

See Also:
/**
     * This is the reader to be used for input from scripts.
     * By default, a <code>InputStreamReader</code> based on <code>System.in</code>
     * is used and default charset is used by this reader. Accessor methods
     * getReader, setReader are used to manage this field.
     * @see java.lang.System#in
     * @see java.io.InputStreamReader
     */
    protected Reader reader;


    
This is the engine scope bindings.
By default, a SimpleBindings is used. Accessor
methods setBindings, getBindings are used to manage this field.

See Also:
  • SimpleBindings
/**
     * This is the engine scope bindings.
     * By default, a <code>SimpleBindings</code> is used. Accessor
     * methods setBindings, getBindings are used to manage this field.
     * @see SimpleBindings
     */
    protected Bindings engineScope;

    
This is the global scope bindings.
By default, a null value (which means no global scope) is used. Accessor
methods setBindings, getBindings are used to manage this field.

/**
     * This is the global scope bindings.
     * By default, a null value (which means no global scope) is used. Accessor
     * methods setBindings, getBindings are used to manage this field.
     */
    protected Bindings globalScope;

    
Create a SimpleScriptContext. 
/**
     * Create a {@code SimpleScriptContext}.
     */
    public SimpleScriptContext() {
        this(new InputStreamReader(System.in),
             new PrintWriter(System.out , true),
             new PrintWriter(System.err, true));
        engineScope = new SimpleBindings();
        globalScope = null;
    }

    
Package-private constructor to avoid needless creation of reader and writers.
It is the caller's responsability to initialize the engine scope.

Params:
  • reader – the reader
  • writer – the writer
  • errorWriter – the error writer
/**
     * Package-private constructor to avoid needless creation of reader and writers.
     * It is the caller's responsability to initialize the engine scope.
     *
     * @param reader the reader
     * @param writer the writer
     * @param errorWriter the error writer
     */
    SimpleScriptContext(Reader reader, Writer writer, Writer errorWriter) {
        this.reader = reader;
        this.writer = writer;
        this.errorWriter = errorWriter;
    }

    
Sets a Bindings of attributes for the given scope.  If the value
of scope is ENGINE_SCOPE the given Bindings replaces the
engineScope field.  If the value
of scope is GLOBAL_SCOPE the given Bindings replaces the
globalScope field.

Params:
  • bindings – The Bindings of attributes to set.
  • scope – The value of the scope in which the attributes are set.
Throws:
/**
     * Sets a <code>Bindings</code> of attributes for the given scope.  If the value
     * of scope is <code>ENGINE_SCOPE</code> the given <code>Bindings</code> replaces the
     * <code>engineScope</code> field.  If the value
     * of scope is <code>GLOBAL_SCOPE</code> the given <code>Bindings</code> replaces the
     * <code>globalScope</code> field.
     *
     * @param bindings The <code>Bindings</code> of attributes to set.
     * @param scope The value of the scope in which the attributes are set.
     *
     * @throws IllegalArgumentException if scope is invalid.
     * @throws NullPointerException if the value of scope is <code>ENGINE_SCOPE</code> and
     * the specified <code>Bindings</code> is null.
     */
    public void setBindings(Bindings bindings, int scope) {

        switch (scope) {

            case ENGINE_SCOPE:
                if (bindings == null) {
                    throw new NullPointerException("Engine scope cannot be null.");
                }
                engineScope = bindings;
                break;
            case GLOBAL_SCOPE:
                globalScope = bindings;
                break;
            default:
                throw new IllegalArgumentException("Invalid scope value.");
        }
    }


    
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 attribute to retrieve.
Throws:
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 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) {
        checkName(name);
        if (engineScope.containsKey(name)) {
            return getAttribute(name, ENGINE_SCOPE);
        } else if (globalScope != null && globalScope.containsKey(name)) {
            return getAttribute(name, GLOBAL_SCOPE);
        }

        return null;
    }

    
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:
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) {
        checkName(name);
        switch (scope) {

            case ENGINE_SCOPE:
                return engineScope.get(name);

            case GLOBAL_SCOPE:
                if (globalScope != null) {
                    return globalScope.get(name);
                }
                return null;

            default:
                throw new IllegalArgumentException("Illegal scope value.");
        }
    }

    
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:
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) {
        checkName(name);
        switch (scope) {

            case ENGINE_SCOPE:
                if (getBindings(ENGINE_SCOPE) != null) {
                    return getBindings(ENGINE_SCOPE).remove(name);
                }
                return null;

            case GLOBAL_SCOPE:
                if (getBindings(GLOBAL_SCOPE) != null) {
                    return getBindings(GLOBAL_SCOPE).remove(name);
                }
                return null;

            default:
                throw new IllegalArgumentException("Illegal scope value.");
        }
    }

    
Sets the value of an attribute in a given scope. If the scope is GLOBAL_SCOPE
and no Bindings is set for GLOBAL_SCOPE, then setAttribute call is a no-op.

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:
/**
     * Sets the value of an attribute in a given scope. If the scope is <code>GLOBAL_SCOPE</code>
     * and no Bindings is set for <code>GLOBAL_SCOPE</code>, then setAttribute call is a no-op.
     *
     * @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) {
        checkName(name);
        switch (scope) {

            case ENGINE_SCOPE:
                engineScope.put(name, value);
                return;

            case GLOBAL_SCOPE:
                if (globalScope != null) {
                    globalScope.put(name, value);
                }
                return;

            default:
                throw new IllegalArgumentException("Illegal scope value.");
        }
    }

    
{@inheritDoc} 
/** {@inheritDoc} */
    public Writer getWriter() {
        return writer;
    }

    
{@inheritDoc} 
/** {@inheritDoc} */
    public Reader getReader() {
        return reader;
    }

    
{@inheritDoc} 
/** {@inheritDoc} */
    public void setReader(Reader reader) {
        this.reader = reader;
    }

    
{@inheritDoc} 
/** {@inheritDoc} */
    public void setWriter(Writer writer) {
        this.writer = writer;
    }

    
{@inheritDoc} 
/** {@inheritDoc} */
    public Writer getErrorWriter() {
        return errorWriter;
    }

    
{@inheritDoc} 
/** {@inheritDoc} */
    public void setErrorWriter(Writer writer) {
        this.errorWriter = writer;
    }

    
Get the lowest scope in which an attribute is defined.

Params:
  • name – Name of the attribute
.
Throws:
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) {
        checkName(name);
        if (engineScope.containsKey(name)) {
            return ENGINE_SCOPE;
        } else if (globalScope != null && globalScope.containsKey(name)) {
            return GLOBAL_SCOPE;
        } else {
            return -1;
        }
    }

    
Returns the value of the engineScope field if specified scope is
ENGINE_SCOPE.  Returns the value of the globalScope field if the specified scope is
GLOBAL_SCOPE.

Params:
  • scope – The specified scope
Throws:
Returns:The value of either the  engineScope or globalScope field.
/**
     * Returns the value of the <code>engineScope</code> field if specified scope is
     * <code>ENGINE_SCOPE</code>.  Returns the value of the <code>globalScope</code> field if the specified scope is
     * <code>GLOBAL_SCOPE</code>.
     *
     * @param scope The specified scope
     * @return The value of either the  <code>engineScope</code> or <code>globalScope</code> field.
     * @throws IllegalArgumentException if the value of scope is invalid.
     */
    public Bindings getBindings(int scope) {
        if (scope == ENGINE_SCOPE) {
            return engineScope;
        } else if (scope == GLOBAL_SCOPE) {
            return globalScope;
        } else {
            throw new IllegalArgumentException("Illegal scope value.");
        }
    }

    
{@inheritDoc} 
/** {@inheritDoc} */
    public List<Integer> getScopes() {
        return scopes;
    }

    private void checkName(String name) {
        Objects.requireNonNull(name);
        if (name.isEmpty()) {
            throw new IllegalArgumentException("name cannot be empty");
        }
    }

    private static List<Integer> scopes;
    static {
        scopes = new ArrayList<Integer>(2);
        scopes.add(ENGINE_SCOPE);
        scopes.add(GLOBAL_SCOPE);
        scopes = Collections.unmodifiableList(scopes);
    }
}