JSEvaluator (Apache Commons SCXML 2.0-SNAPSHOT API)

java.lang.Object
- org.apache.commons.scxml2.env.javascript.JSEvaluator

All Implemented Interfaces:

Evaluator
```
public class JSEvaluator
extends Object
implements Evaluator
```
Embedded JavaScript expression evaluator for SCXML expressions. This implementation is a just a 'thin' wrapper around the Javascript engine in JDK 6 (based on on Mozilla Rhino 1.6.2).
Mozilla Rhino 1.6.2 does not support E4X so accessing the SCXML data model is implemented in the same way as the JEXL expression evaluator i.e. using the Data() function, for example, <assign location="Data(hotelbooking,'hotel/rooms')" expr="2" />

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

static class JSEvaluator.JSEvaluatorProvider
- Nested classes/interfaces inherited from interface org.apache.commons.scxml2.Evaluator
  Evaluator.AssignType

Nested Classes
Modifier and Type	Class and Description
`static class`	`JSEvaluator.JSEvaluatorProvider`

Field Summary

Fields
Modifier and Type Field and Description

static String SUPPORTED_DATA_MODEL
- Fields inherited from interface org.apache.commons.scxml2.Evaluator
  DEFAULT_DATA_MODEL, ECMASCRIPT_DATA_MODEL, NULL_DATA_MODEL, XPATH_DATA_MODEL

Fields
Modifier and Type	Field and Description
`static String`	`SUPPORTED_DATA_MODEL`

Constructor Summary

Constructors
Constructor and Description

JSEvaluator()
Initialises the internal Javascript engine factory.

Constructors
Constructor and Description
`JSEvaluator()` Initialises the internal Javascript engine factory.

Method Summary

Methods
Modifier and Type	Method and Description
`Object`	`eval(Context context, String expression)` Evaluates the expression using a new Javascript engine obtained from factory instantiated in the constructor.
`void`	`evalAssign(Context ctx, String location, Object data, Evaluator.AssignType type, String attr)` Assigns data to a location
`Boolean`	`evalCond(Context context, String expression)` Evaluates a conditional expression using the `eval()` method and casting the result to a Boolean.
`Object`	`evalLocation(Context context, String expression)` Evaluates a location expression using a new Javascript engine obtained from factory instantiated in the constructor.
`Object`	`evalScript(Context ctx, String script)` Executes the script using a new Javascript engine obtained from factory instantiated in the constructor.
`protected JSContext`	`getEffectiveContext(JSContext nodeCtx)` Create a new context which is the summation of contexts from the current state to document root, child has priority over parent in scoping rules.
`String`	`getSupportedDatamodel()` Get the datamodel type supported by this Evaluator
`Context`	`newContext(Context parent)` Creates a child context.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - SUPPORTED_DATA_MODEL
```
public static final String SUPPORTED_DATA_MODEL
```
    See Also:
    Constant Field Values
- Constructor Detail
  - JSEvaluator
```
public JSEvaluator()
```
    Initialises the internal Javascript engine factory.
- Method Detail
  - getSupportedDatamodel
```
public String getSupportedDatamodel()
```
    Description copied from interface: Evaluator
    
    Get the datamodel type supported by this Evaluator
    
    Specified by:
    
    getSupportedDatamodel in interface Evaluator
    
    Returns:
    The supported datamodel type
  - newContext
```
public Context newContext(Context parent)
```
    Creates a child context.
    
    Specified by:
    
    newContext in interface Evaluator
    
    Parameters:
    parent - parent context
    
    Returns:
    Returns a new child JSContext.
  - eval
```
public Object eval(Context context,
          String expression)
            throws SCXMLExpressionException
```
    Evaluates the expression using a new Javascript engine obtained from factory instantiated in the constructor. The engine is supplied with a new JSBindings that includes the SCXML Context and Data() functions are replaced with an equivalent internal Javascript function.
    
    Specified by:
    
    eval in interface Evaluator
    
    Parameters:
    context - SCXML context.
    expression - Expression to evaluate.
    
    Returns:
    Result of expression evaluation or null.
    
    Throws:
    
    SCXMLExpressionException - Thrown if the expression was invalid.
  - evalCond
```
public Boolean evalCond(Context context,
               String expression)
                 throws SCXMLExpressionException
```
    Evaluates a conditional expression using the eval() method and casting the result to a Boolean.
    
    Specified by:
    
    evalCond in interface Evaluator
    
    Parameters:
    context - SCXML context.
    expression - Expression to evaluate.
    
    Returns:
    Boolean or null.
    
    Throws:
    
    SCXMLExpressionException - Thrown if the expression was invalid or did not return a boolean.
  - evalLocation
```
public Object evalLocation(Context context,
                  String expression)
                    throws SCXMLExpressionException
```
    Evaluates a location expression using a new Javascript engine obtained from factory instantiated in the constructor. The engine is supplied with a new JSBindings that includes the SCXML Context and Data() functions are replaced with an equivalent internal Javascript function.
    
    Specified by:
    
    evalLocation in interface Evaluator
    
    Parameters:
    context - FSM context.
    expression - Expression to evaluate.
    
    Returns:
    The location result.
    
    Throws:
    
    SCXMLExpressionException - Thrown if the expression was invalid.
  - evalAssign
```
public void evalAssign(Context ctx,
              String location,
              Object data,
              Evaluator.AssignType type,
              String attr)
                throws SCXMLExpressionException
```
    Description copied from interface: Evaluator
    
    Assigns data to a location
    
    Specified by:
    
    evalAssign in interface Evaluator
    
    Parameters:
    ctx - variable context
    location - location expression
    data - the data to assign.
    type - the type of assignment to perform, null assumes Evaluator.AssignType.REPLACE_CHILDREN
    attr - the name of the attribute to add when using type Evaluator.AssignType.ADD_ATTRIBUTE
    
    Throws:
    
    SCXMLExpressionException - A malformed expression exception
    See Also:
    Evaluator.evalAssign(Context, String, Object, AssignType, String)
  - evalScript
```
public Object evalScript(Context ctx,
                String script)
                  throws SCXMLExpressionException
```
    Executes the script using a new Javascript engine obtained from factory instantiated in the constructor. The engine is supplied with a new JSBindings that includes the SCXML Context and Data() functions are replaced with an equivalent internal Javascript function.
    
    Specified by:
    
    evalScript in interface Evaluator
    
    Parameters:
    ctx - SCXML context.
    script - Script to execute.
    
    Returns:
    Result of script execution or null.
    
    Throws:
    
    SCXMLExpressionException - Thrown if the script was invalid.
  - getEffectiveContext
```
protected JSContext getEffectiveContext(JSContext nodeCtx)
```
    Create a new context which is the summation of contexts from the current state to document root, child has priority over parent in scoping rules.
    
    Parameters:
    nodeCtx - The JexlContext for this state.
    
    Returns:
    The effective JexlContext for the path leading up to document root.

Class JSEvaluator

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.commons.scxml2.Evaluator

Field Summary

Fields inherited from interface org.apache.commons.scxml2.Evaluator

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

SUPPORTED_DATA_MODEL

Constructor Detail

JSEvaluator

Method Detail

getSupportedDatamodel

newContext

eval

evalCond

evalLocation

evalAssign

evalScript

getEffectiveContext