Evaluator (rabbitmq-jms 3.2.0 API)

All Known Implementing Classes:

SqlEvaluator
```
public interface Evaluator
```
An Evaluator will evaluate an expression.
An evaluator takes a set of values (the environment) and evaluates an expression in it, returning a Result. For example, it might evaluate a (previously given) boolean expression given a set of values assigned to variables.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`boolean`	`evaluate(java.util.Map<java.lang.String,java.lang.Object> env)`	Evaluates the (given) expression with the `env`ironment given.
`boolean`	`evaluatorOk()`	This call is idempotent.
`java.lang.String`	`getErrorMessage()`	This call is idempotent.

- Method Detail
  - evaluate
```
boolean evaluate(java.util.Map<java.lang.String,java.lang.Object> env)
```
    Evaluates the (given) expression with the environment given. This call should not fail, provided evaluatorOk() is true.
    
    Parameters:
    
    env - - the values of the variables used when evaluating the expression
    
    Returns:
    
    the evaluated result: true or false
  - evaluatorOk
```
boolean evaluatorOk()
```
    This call is idempotent.
    
    Returns:
    
    true if the evaluator can run cleanly; false otherwise
  - getErrorMessage
```
java.lang.String getErrorMessage()
```
    This call is idempotent.
    
    Returns:
    
    null if evaluatorOk() is false; otherwise an error message denoting the type of failure to initialise.