Class AbstractScriptEngine

public abstract class AbstractScriptEngine
extends Object
implements ScriptEngine

Provides a standard implementation for several of the variants of the eval method.

eval(Reader)

eval(String)

eval(String, Bindings)

eval(Reader, Bindings)

are implemented using the abstract methods

eval(Reader,ScriptContext) or eval(String, ScriptContext)

with a SimpleScriptContext.

A SimpleScriptContext is used as the default ScriptContext of the AbstractScriptEngine..

Fields

context

protected ScriptContext context

The default ScriptContext of this AbstractScriptEngine.

Constructors

AbstractScriptEngine

public AbstractScriptEngine()

Creates a new instance of AbstractScriptEngine using a SimpleScriptContext as its default ScriptContext.

AbstractScriptEngine

public AbstractScriptEngine(Bindings n)

Creates a new instance using the specified Bindings as the ENGINE_SCOPE Bindings in the protected context field.

Parameters:

n - The specified Bindings.

Throws:

NullPointerException - if n is null.

Methods

setContext

public void setContext(ScriptContext ctxt)

Sets the value of the protected context field to the specified ScriptContext.

Specified by:

setContext in interface ScriptEngine

Parameters:

ctxt - The specified ScriptContext.

Throws:

NullPointerException - if ctxt is null.

getContext

public ScriptContext getContext()

Returns the value of the protected context field.

Specified by:

getContext in interface ScriptEngine

Returns:

The value of the protected context field.

getBindings

public Bindings getBindings(int scope)

Returns the Bindings with the specified scope value in the protected context field.

Specified by:

getBindings in interface ScriptEngine

Parameters:

scope - The specified scope

Returns:

The corresponding Bindings.

Throws:

IllegalArgumentException - if the value of scope is invalid for the type the protected context field.

setBindings

public void setBindings(Bindings bindings,
                        int scope)

Sets the Bindings with the corresponding scope value in the context field.

Specified by:

setBindings in interface ScriptEngine

Parameters:

bindings - The specified Bindings.

scope - The specified scope.

Throws:

IllegalArgumentException - if the value of scope is invalid for the type the context field.

NullPointerException - if the bindings is null and the scope is ScriptContext.ENGINE_SCOPE

put

public void put(String key,
                Object value)

Sets the specified value with the specified key in the ENGINE_SCOPE Bindings of the protected context field.

Specified by:

put in interface ScriptEngine

Parameters:

key - The specified key.

value - The specified value.

Throws:

NullPointerException - if key is null.

IllegalArgumentException - if key is empty.

get

public Object get(String key)

Gets the value for the specified key in the ENGINE_SCOPE of the protected context field.

Specified by:

get in interface ScriptEngine

Parameters:

key - The key whose value is to be returned

Returns:

The value for the specified key.

Throws:

NullPointerException - if key is null.

IllegalArgumentException - if key is empty.

eval

public Object eval(Reader reader,
                   Bindings bindings)
            throws ScriptException

eval(Reader, Bindings) calls the abstract eval(Reader, ScriptContext) method, passing it a ScriptContext whose Reader, Writers and Bindings for scopes other that ENGINE_SCOPE are identical to those members of the protected context field. The specified Bindings is used instead of the ENGINE_SCOPE Bindings of the context field.

Specified by:

eval in interface ScriptEngine

Parameters:

reader - A Reader containing the source of the script.

bindings - A Bindings to use for the ENGINE_SCOPE while the script executes.

Returns:

The return value from eval(Reader, ScriptContext)

Throws:

ScriptException - if an error occurs in script.

NullPointerException - if any of the parameters is null.

eval

public Object eval(String script,
                   Bindings bindings)
            throws ScriptException

Same as eval(Reader, Bindings) except that the abstract eval(String, ScriptContext) is used.

Specified by:

eval in interface ScriptEngine

Parameters:

script - A String containing the source of the script.

bindings - A Bindings to use as the ENGINE_SCOPE while the script executes.

Returns:

The return value from eval(String, ScriptContext)

Throws:

ScriptException - if an error occurs in script.

NullPointerException - if any of the parameters is null.

eval

public Object eval(Reader reader)
            throws ScriptException

eval(Reader) calls the abstract eval(Reader, ScriptContext) passing the value of the context field.

Specified by:

eval in interface ScriptEngine

Parameters:

reader - A Reader containing the source of the script.

Returns:

The return value from eval(Reader, ScriptContext)

Throws:

ScriptException - if an error occurs in script.

NullPointerException - if any of the parameters is null.

eval

public Object eval(String script)
            throws ScriptException

Same as eval(Reader) except that the abstract eval(String, ScriptContext) is used.

Specified by:

eval in interface ScriptEngine

Parameters:

script - A String containing the source of the script.

Returns:

The return value from eval(String, ScriptContext)

Throws:

ScriptException - if an error occurs in script.

NullPointerException - if any of the parameters is null.

getScriptContext

protected ScriptContext getScriptContext(Bindings nn)

Returns a SimpleScriptContext. The SimpleScriptContext:

• Uses the specified Bindings for its ENGINE_SCOPE
• Uses the Bindings returned by the abstract getGlobalScope method as its GLOBAL_SCOPE
• Uses the Reader and Writer in the default ScriptContext of this ScriptEngine

A SimpleScriptContext returned by this method is used to implement eval methods using the abstract eval(Reader,Bindings) and eval(String,Bindings) versions.

Parameters:

nn - Bindings to use for the ENGINE_SCOPE

Returns:

The SimpleScriptContext