package org.drools.compiler;
/*
* Copyright 2005 JBoss Inc
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import java.io.IOException;
import java.io.Reader;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import org.antlr.runtime.ANTLRReaderStream;
import org.antlr.runtime.ANTLRStringStream;
import org.antlr.runtime.CommonTokenStream;
import org.antlr.runtime.RecognitionException;
import org.drools.lang.DRLLexer;
import org.drools.lang.DRLParser;
import org.drools.lang.Expander;
import org.drools.lang.ExpanderException;
import org.drools.lang.Location;
import org.drools.lang.descr.PackageDescr;
import org.drools.lang.dsl.DefaultExpanderResolver;
/**
* This is a low level parser API. This will return textual AST representations
* of the DRL source, including with DSL expanders if appropriate.
*/
public class DrlParser {
private final List results = new ArrayList();
private Location location = null;
public DrlParser() {
}
/** Parse a rule from text */
public PackageDescr parse(final String text) throws DroolsParserException {
final DRLParser parser = getParser( text );
compile( parser );
this.location = parser.getLocation();
return parser.getPackageDescr();
}
public PackageDescr parse(final Reader reader) throws DroolsParserException {
final DRLParser parser = getParser( reader );
compile( parser );
this.location = parser.getLocation();
return parser.getPackageDescr();
}
// /** Parse and build a rule package from a DRL source */
// public PackageDescr parse(final Reader reader) throws IOException,
// DroolsParserException {
// DRLParser parser =
//
// //final StringBuffer text = getDRLText( reader );
// //return parse( text.toString() );
// }
/**
* Parse and build a rule package from a DRL source with a
* domain specific language.
*/
public PackageDescr parse(final Reader drl,
final Reader dsl) throws DroolsParserException,
IOException {
final StringBuffer text = getDRLText( drl );
return parse( text.toString(),
dsl );
}
/**
* Parse and build a rule package from a DRL source with a domain specific language.
* @param source As Text.
* @param dsl
* @return
* @throws DroolsParserException
*/
public PackageDescr parse(final String source,
final Reader dsl) throws DroolsParserException {
DefaultExpanderResolver resolver;
try {
resolver = new DefaultExpanderResolver( dsl );
} catch ( final IOException e ) {
throw new DroolsParserException( "Error parsing the DSL.",
e );
}
final Expander expander = resolver.get( "*",
null );
final String expanded = expander.expand( source );
if ( expander.hasErrors() ) {
this.results.addAll( expander.getErrors() );
}
return this.parse( expanded );
}
/**
* This will expand the DRL.
* useful for debugging.
* @param source - the source which use a DSL
* @param dsl - the DSL itself.
* @throws DroolsParserException If unable to expand in any way.
*/
public String getExpandedDRL(final String source, final Reader dsl) throws DroolsParserException {
DefaultExpanderResolver resolver;
try {
resolver = new DefaultExpanderResolver( dsl );
} catch ( final IOException e ) {
throw new DroolsParserException( "Error parsing the DSL.",
e );
}
final Expander expander = resolver.get( "*",
null );
final String expanded = expander.expand( source );
if ( expander.hasErrors() ) {
String err = "";
for ( Iterator iter = expander.getErrors().iterator(); iter.hasNext(); ) {
ExpanderException ex = (ExpanderException) iter.next();
err = err + "\n Line:[" + ex.getLine() + "] " + ex.getMessage();
}
throw new DroolsParserException(err);
}
return expanded;
}
private StringBuffer getDRLText(final Reader reader) throws IOException {
final StringBuffer text = new StringBuffer();
final char[] buf = new char[1024];
int len = 0;
while ( (len = reader.read( buf )) >= 0 ) {
text.append( buf,
0,
len );
}
return text;
}
/**
* @return true if there were parser errors.
*/
public boolean hasErrors() {
return this.results.size() > 0;
}
/**
* @return a list of ParserError's.
*/
public List getErrors() {
return this.results;
}
private void compile(final DRLParser parser) throws DroolsParserException {
try {
parser.compilation_unit();
makeErrorList( parser );
} catch ( final RecognitionException e ) {
throw new DroolsParserException( e );
} catch ( Exception e ) {
throw new DroolsParserException( "Unknown error while parsing. This is a bug. Please contact the Development team.", e);
}
}
/** Convert the antlr exceptions to drools parser exceptions */
private void makeErrorList(final DRLParser parser) {
for ( final Iterator iter = parser.getErrors().iterator(); iter.hasNext(); ) {
final RecognitionException recogErr = (RecognitionException) iter.next();
final ParserError err = new ParserError( parser.createErrorMessage( recogErr ),
recogErr.line,
recogErr.charPositionInLine );
this.results.add( err );
}
}
/**
* @return An instance of a RuleParser should you need one (most folks will not).
*/
private DRLParser getParser(final String text) {
return new DRLParser( new CommonTokenStream( new DRLLexer( new ANTLRStringStream( text ) ) ) );
}
private DRLParser getParser(final Reader reader) {
try {
return new DRLParser( new CommonTokenStream( new DRLLexer( new ANTLRReaderStream( reader ) ) ) );
} catch ( final Exception e ) {
throw new RuntimeException( "Unable to parser Reader",
e );
}
}
public Location getLocation() {
return this.location;
}
}