package org.drools.rule.builder.dialect.mvel;
import java.io.Serializable;
import java.util.HashMap;
import java.util.Map;
import org.drools.base.mvel.DroolsMVELFactory;
import org.drools.base.mvel.MVELConsequence;
import org.drools.compiler.Dialect;
import org.drools.compiler.RuleError;
import org.drools.rule.builder.ConsequenceBuilder;
import org.drools.rule.builder.RuleBuildContext;
import org.mvel.Macro;
import org.mvel.MacroProcessor;
public class MVELConsequenceBuilder
implements
ConsequenceBuilder {
//private final Interceptor assertInterceptor;
//private final Interceptor modifyInterceptor;
private final Map macros;
public MVELConsequenceBuilder() {
macros = new HashMap( 4 );
macros.put( "insert",
new Macro() {
public String doMacro() {
return "drools.insert";
}
} );
macros.put( "modify",
new Macro() {
public String doMacro() {
return "@Modify with";
}
} );
macros.put( "update",
new Macro() {
public String doMacro() {
return "drools.update";
}
} );
macros.put( "retract",
new Macro() {
public String doMacro() {
return "drools.retract";
}
} );
}
public void build(final RuleBuildContext context) {
// pushing consequence LHS into the stack for variable resolution
context.getBuildStack().push( context.getRule().getLhs() );
try {
MVELDialect dialect = (MVELDialect) context.getDialect();
String text = processMacros( (String) context.getRuleDescr().getConsequence() );
Dialect.AnalysisResult analysis = dialect.analyzeBlock( context,
context.getRuleDescr(),
dialect.getInterceptors(),
text,
null );
final Serializable expr = dialect.compile( text,
analysis,
dialect.getInterceptors(),
null,
context );
final DroolsMVELFactory factory = new DroolsMVELFactory( context.getDeclarationResolver().getDeclarations(),
null,
context.getPkg().getGlobals(),
analysis.getBoundIdentifiers() );
factory.setNextFactory( dialect.getStaticMethodImportResolverFactory() );
context.getRule().setConsequence( new MVELConsequence( expr,
factory ) );
} catch ( final Exception e ) {
context.getErrors().add( new RuleError( context.getRule(),
context.getRuleDescr(),
null,
"Unable to build expression for 'consequence' '" + context.getRuleDescr().getConsequence() + "'" ) );
}
}
public String processMacros(String consequence) {
MacroProcessor macroProcessor = new MacroProcessor();
macroProcessor.setMacros( macros );
return macroProcessor.parse( delimitExpressions( consequence ) );
}
/**
* Allows newlines to demarcate expressions, as per MVEL command line.
* If expression spans multiple lines (ie inside an unbalanced bracket) then
* it is left alone.
* Uses character based iteration which is at least an order of magnitude faster then a single
* simple regex.
*/
public static String delimitExpressions(String s) {
StringBuffer result = new StringBuffer();
char[] cs = s.toCharArray();
int brace = 0;
int sqre = 0;
int crly = 0;
char lastNonWhite = ';';
for ( int i = 0; i < cs.length; i++ ) {
char c = cs[i];
switch ( c ) {
case '(' :
brace++;
break;
case '{' :
crly++;
break;
case '[' :
sqre++;
break;
case ')' :
brace--;
break;
case '}' :
crly--;
break;
case ']' :
sqre--;
break;
default :
break;
}
if ( (brace == 0 && sqre == 0 && crly == 0) && (c == '\n' || c == '\r') ) {
if ( lastNonWhite != ';' ) {
result.append( ';' );
lastNonWhite = ';';
}
} else if ( !Character.isWhitespace( c ) ) {
lastNonWhite = c;
}
result.append( c );
}
return result.toString();
}
}