Evaluator (Apache Commons SCXML 2.0-SNAPSHOT API)

All Known Implementing Classes:

GroovyEvaluator, JexlEvaluator, JSEvaluator, MinimalEvaluator, XPathEvaluator
```
public interface Evaluator
```
Interface for a component that may be used by the SCXML engines to evaluate the expressions within the SCXML document.

Nested Class Summary

Nested Classes
Modifier and Type Interface and Description

static class Evaluator.AssignType
The allowable types of including and in particular when using XPath

Nested Classes
Modifier and Type	Interface and Description
`static class`	`Evaluator.AssignType` The allowable types of including and in particular when using XPath

Field Summary

Fields
Modifier and Type	Field and Description
`static String`	`DEFAULT_DATA_MODEL` Default Data Model name
`static String`	`ECMASCRIPT_DATA_MODEL` SCXML 1.0 ECMAScript Data Model name
`static String`	`NULL_DATA_MODEL` SCXML 1.0 Null Data Model name
`static String`	`XPATH_DATA_MODEL` SCXML 1.0 XPath Data Model name

Method Summary

Methods
Modifier and Type	Method and Description
`Object`	`eval(Context ctx, String expr)` Evaluate an expression returning a data value
`void`	`evalAssign(Context ctx, String location, Object data, Evaluator.AssignType type, String attr)` Assigns data to a location
`Boolean`	`evalCond(Context ctx, String expr)` Evaluate a condition.
`Object`	`evalLocation(Context ctx, String expr)` Evaluate a location that returns a data assignable reference or list of references.
`Object`	`evalScript(Context ctx, String script)` Evaluate a script.
`String`	`getSupportedDatamodel()` Get the datamodel type supported by this Evaluator
`Context`	`newContext(Context parent)` Create a new child context.

- Field Detail
  - NULL_DATA_MODEL
```
static final String NULL_DATA_MODEL
```
    SCXML 1.0 Null Data Model name
    
    See Also:
    Constant Field Values
  - ECMASCRIPT_DATA_MODEL
```
static final String ECMASCRIPT_DATA_MODEL
```
    SCXML 1.0 ECMAScript Data Model name
    
    See Also:
    Constant Field Values
  - XPATH_DATA_MODEL
```
static final String XPATH_DATA_MODEL
```
    SCXML 1.0 XPath Data Model name
    
    See Also:
    Constant Field Values
  - DEFAULT_DATA_MODEL
```
static final String DEFAULT_DATA_MODEL
```
    Default Data Model name
    
    See Also:
    Constant Field Values
- Method Detail
  - getSupportedDatamodel
```
String getSupportedDatamodel()
```
    Get the datamodel type supported by this Evaluator
    
    Returns:
    The supported datamodel type
  - eval
```
Object eval(Context ctx,
          String expr)
            throws SCXMLExpressionException
```
    Evaluate an expression returning a data value
    
    Parameters:
    ctx - variable context
    expr - expression
    
    Returns:
    the result of the evaluation
    
    Throws:
    
    SCXMLExpressionException - A malformed expression exception
  - evalCond
```
Boolean evalCond(Context ctx,
               String expr)
                 throws SCXMLExpressionException
```
    Evaluate a condition. Manifests as "cond" attributes of <transition>, <if> and <elseif> elements.
    
    Parameters:
    ctx - variable context
    expr - expression
    
    Returns:
    true/false
    
    Throws:
    
    SCXMLExpressionException - A malformed expression exception
  - evalLocation
```
Object evalLocation(Context ctx,
                  String expr)
                    throws SCXMLExpressionException
```
    Evaluate a location that returns a data assignable reference or list of references. Manifests as "location" attributes of <assign> element.
    
    Parameters:
    ctx - variable context
    expr - expression
    
    Returns:
    The location result.
    
    Throws:
    
    SCXMLExpressionException - A malformed expression exception
  - evalAssign
```
void evalAssign(Context ctx,
              String location,
              Object data,
              Evaluator.AssignType type,
              String attr)
                throws SCXMLExpressionException
```
    Assigns data to a location
    
    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
  - evalScript
```
Object evalScript(Context ctx,
                String script)
                  throws SCXMLExpressionException
```
    Evaluate a script. Manifests as <script> element.
    
    Parameters:
    ctx - variable context
    script - The script
    
    Returns:
    The result of the script execution.
    
    Throws:
    
    SCXMLExpressionException - A malformed script
  - newContext
```
Context newContext(Context parent)
```
    Create a new child context.
    
    Parameters:
    parent - parent context
    
    Returns:
    new child context

Interface Evaluator

Nested Class Summary

Field Summary

Method Summary

Field Detail

NULL_DATA_MODEL

ECMASCRIPT_DATA_MODEL

XPATH_DATA_MODEL

DEFAULT_DATA_MODEL

Method Detail

getSupportedDatamodel

eval

evalCond

evalLocation

evalAssign

evalScript

newContext