Examples of org.drools.compiler.lang.Expander

org.drools.compiler.lang.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.


    /**
     * Returns an expander for DSLs (only if there is a DSL configured for this package).
     */
    public Expander getDSLExpander( final Path path ) {
        final Expander expander = new DefaultExpander();
        final List<DSLMappingFile> dsls = getDSLMappingFiles( path );
        for ( DSLMappingFile dsl : dsls ) {
            expander.addDSLMapping( dsl.getMapping() );
        }
        return expander;
    }

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        DefaultExpanderResolver resolver = new DefaultExpanderResolver(new StringReader(dsl));
        
        
        final DSLMappingFile file = new DSLTokenizedMappingFile();
        if ( file.parseAndLoad( new StringReader(dsl) ) ) {
            final Expander expander = new DefaultExpander();
            expander.addDSLMapping( file.getMapping() );
            resolver.addExpander("*", expander);
        } else {
            throw new RuntimeException( "Error parsing and loading DSL file." + file.getErrors() );
        }

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    @Test
    public void testMultiLineTemplates() throws Exception {
        final Reader source = new InputStreamReader( getClass().getResourceAsStream( "rule_with_expander_multiline.dslr" ) );
        final Reader dsl = new InputStreamReader( getClass().getResourceAsStream( "test_dsl_multiline.dsl" ) );
        Expander ex =  new DefaultExpanderResolver(dsl).get("*", null);
        String r = ex.expand(source);
        assertEquals("when Car(color==\"Red\") then doSomething();", r.trim());
    }

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    @Override
    public String getSource( final Path path,
                             final RuleModel model ) {
        final String dslr = RuleModelDRLPersistenceImpl.getInstance().marshal( model );
        final Expander expander = getDSLExpander( path );
        final String drl = expander.expand( dslr );
        return drl;
    }

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    /**
     * Returns an expander for DSLs (only if there is a DSL configured for this package).
     */
    public Expander getDSLExpander( final Path path ) {
        final Expander expander = new DefaultExpander();
        final List<DSLMappingFile> dsls = getDSLMappingFiles( path );
        for ( DSLMappingFile dsl : dsls ) {
            expander.addDSLMapping( dsl.getMapping() );
        }
        return expander;
    }

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    public KObject toKObject( final Path path ) {


        KObject index = null;
        try {
            final String dslr = ioService.readAllString( path );
            final Expander expander = getDSLExpander( path );
            final String drl = expander.expand( dslr );
            final DrlParser drlParser = new DrlParser();
            final PackageDescr packageDescr = drlParser.parse( true,
                                                               drl );
            if ( packageDescr == null ) {
                logger.error( "Unable to parse DRL for '" + path.toUri().toString() + "'." );

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    /**
     * Returns an expander for DSLs (only if there is a DSL configured for this package).
     */
    private Expander getDSLExpander( final Path path ) {
        final Expander expander = new DefaultExpander();
        final List<DSLMappingFile> dsls = getDSLMappingFiles( path );
        for ( DSLMappingFile dsl : dsls ) {
            expander.addDSLMapping( dsl.getMapping() );
        }
        return expander;
    }

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        DefaultExpanderResolver resolver = new DefaultExpanderResolver(new StringReader(dsl));
        
        
        final DSLMappingFile file = new DSLTokenizedMappingFile();
        if ( file.parseAndLoad( new StringReader(dsl) ) ) {
            final Expander expander = new DefaultExpander();
            expander.addDSLMapping( file.getMapping() );
            resolver.addExpander("*", expander);
        } else {
            throw new RuntimeDroolsException( "Error parsing and loading DSL file." + file.getErrors() );
        }

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    public PackageDescr parse(boolean isEditor,
                              final String source,
                              final Reader dsl) throws DroolsParserException {
        DefaultExpanderResolver resolver = getDefaultResolver(dsl);


        final Expander expander = resolver.get( "*", null );
        final String expanded = expander.expand( source );
        if ( expander.hasErrors() ) {
            this.results.addAll( expander.getErrors() );
        }
        return this.parse(isEditor, expanded);
    }

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     *             If unable to expand in any way.
     */
    public String getExpandedDRL(final String source,
                                 final DefaultExpanderResolver resolver) throws DroolsParserException {


        final Expander expander = resolver.get("*",
                null);
        final String expanded = expander.expand( source );
        if ( expander.hasErrors() ) {
            String err = "";
            for ( ExpanderException ex : expander.getErrors() ) {
                err = err + "\n Line:[" + ex.getLine() + "] " + ex.getMessage();


            }
            throw new DroolsParserException( err );
        }

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org.drools.compiler.compiler.DrlParser

org.drools.compiler.compiler.DrlParserTest

org.drools.compiler.integrationtests.DslTest

org.drools.compiler.lang.dsl.DefaultExpanderResolver

org.drools.workbench.screens.drltext.backend.server.indexing.DslrFileIndexer

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