Expander (Drools :: DRL :: Parser 8.42.0.Final API)

All Known Implementing Classes:

DefaultExpander
```
public interface Expander
```
Expanders are extension points for expanding expressions in DRL at parse time. This is just-in-time translation, or macro expansion, or whatever you want. The important thing is that it happens at the last possible moment, so any errors in expansion are included in the parsers errors. Just-in-time expansions may include complex pre-compilers, or just macros, and everything in between. Expanders should ideally not make presumptions on any embedded semantic language. For instance, java aware pre processing should be done in drools-java semantic module, not in the parser itself. Expanders should be reusable across semantic languages.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`void`	`addDSLMapping(DSLMapping mapping)`	Add the new mapping to this expander.
`java.lang.String`	`expand(java.io.Reader drl)`	Expands (process) the expression Just-In-Time for the parser.
`java.lang.String`	`expand(java.lang.String source)`	Expands (process) the expression Just-In-Time for the parser.
`java.util.List<ExpanderException>`	`getErrors()`	Returns the list of errors from the last expansion made
`boolean`	`hasErrors()`	Returns true in case the last expansion had any errors

- Method Detail
  - expand
```
java.lang.String expand(java.io.Reader drl)
                 throws java.io.IOException
```
    Expands (process) the expression Just-In-Time for the parser. If the source is not meant to be expanded, or if no appropriate match was found for expansion, it will echo back the same expression.
    
    Parameters:
    
    drl - the source code to be pre-processed
    
    Returns:
    
    source code after running pre-processors
    
    Throws:
    
    java.io.IOException
  - expand
```
java.lang.String expand(java.lang.String source)
```
    Expands (process) the expression Just-In-Time for the parser. If the source is not meant to be expanded, or if no appropriate match was found for expansion, it will echo back the same expression.
    
    Parameters:
    
    source - the source code to be expanded
    
    Returns:
    
    source code after running pre-processors
  - addDSLMapping
```
void addDSLMapping(DSLMapping mapping)
```
    Add the new mapping to this expander.
    
    Parameters:
    
    mapping -
  - getErrors
```
java.util.List<ExpanderException> getErrors()
```
    Returns the list of errors from the last expansion made
    
    Returns:
    
    A list of ExpanderException
  - hasErrors
```
boolean hasErrors()
```
    Returns true in case the last expansion had any errors
    
    Returns: