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.InputStream;
import java.io.Reader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import org.antlr.runtime.ANTLRInputStream;
import org.antlr.runtime.ANTLRReaderStream;
import org.antlr.runtime.ANTLRStringStream;
import org.antlr.runtime.CommonTokenStream;
import org.antlr.runtime.RecognitionException;
import org.antlr.runtime.TokenStream;
import org.antlr.runtime.tree.CommonTreeNodeStream;
import org.antlr.runtime.tree.Tree;
import org.drools.lang.DRLLexer;
import org.drools.lang.DRLParser;
import org.drools.lang.DescrBuilderTree;
import org.drools.lang.DroolsSentence;
import org.drools.lang.DroolsTree;
import org.drools.lang.DroolsTreeAdaptor;
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 static final String GENERIC_ERROR_MESSAGE = "Unexpected exception raised while parsing. This is a bug. Please contact the Development team :\n";
private final List<DroolsError> results = new ArrayList<DroolsError>();
private List<DroolsSentence> editorSentences = null;
private Location location = new Location( Location.LOCATION_UNKNOWN );
private DescrBuilderTree walker = null;
private DRLLexer lexer = null;
public DrlParser() {
}
/** Parse a rule from text */
public PackageDescr parse(final String text) throws DroolsParserException {
return parse( false,
text );
}
public PackageDescr parse(final boolean isEditor,
final String text) throws DroolsParserException {
final DRLParser parser = getParser( text );
return compile( isEditor,
parser );
}
public PackageDescr parse(final boolean isEditor,
final Reader reader) throws DroolsParserException {
final DRLParser parser = getParser( reader );
return compile( isEditor,
parser );
}
public PackageDescr parse(final Reader reader) throws DroolsParserException {
return parse( false,
reader );
}
/**
* 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 {
return parse( false,
drl,
dsl );
}
public PackageDescr parse(boolean isEditor,
final Reader drl,
final Reader dsl) throws DroolsParserException,
IOException {
final StringBuilder 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(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 );
}
public PackageDescr parse(final String source,
final Reader dsl) throws DroolsParserException {
return this.parse( false,
source,
dsl );
}
public PackageDescr parse(final boolean isEditor,
final InputStream is) throws DroolsParserException {
final DRLParser parser = getParser( is );
return compile( isEditor,
parser );
}
public PackageDescr parse(final InputStream is) throws DroolsParserException {
return parse( false,
is );
}
/**
* 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 = getDefaultResolver( dsl );
return getExpandedDRL( source,
resolver );
}
/**
* This will expand the DRL using the given expander resolver. useful for
* debugging.
*
* @param source -
* the source which use a DSL
* @param resolver -
* the DSL expander resolver itself.
* @throws DroolsParserException
* 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 );
}
return expanded;
}
private StringBuilder getDRLText(final Reader reader) throws IOException {
final StringBuilder text = new StringBuilder();
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.isEmpty();
}
/**
* @return a list of errors found while parsing. DroolsError: either ParserError, or ExpanderException
*/
public List<DroolsError> getErrors() {
return this.results;
}
private PackageDescr compile(boolean isEditor,
final DRLParser parser) throws DroolsParserException {
try {
if ( isEditor ) {
parser.enableEditorInterface();
}
DroolsTree resultTree = (DroolsTree) parser.compilation_unit().getTree();
editorSentences = parser.getEditorInterface();
makeErrorList( parser );
if ( isEditor || !this.hasErrors() ) {
return walk( parser.getTokenStream(),
resultTree );
} else {
return null;
}
} catch ( Exception e ) {
final ParserError err = new ParserError( GENERIC_ERROR_MESSAGE + e.toString()+"\n"+ Arrays.toString( e.getStackTrace() ),
-1,
0 );
this.results.add( err );
if ( isEditor ) {
if ( walker == null ) {
return null;
}
return walker.getPackageDescr();
} else {
throw new DroolsParserException( GENERIC_ERROR_MESSAGE + e.getMessage(),
e );
}
}
}
private PackageDescr walk(TokenStream tokenStream,
Tree resultTree) throws RecognitionException {
CommonTreeNodeStream nodes = new CommonTreeNodeStream( resultTree );
// AST nodes have payload that point into token stream
nodes.setTokenStream( tokenStream );
// Create a tree walker attached to the nodes stream
walker = new DescrBuilderTree( nodes );
walker.compilation_unit();
return walker.getPackageDescr();
}
/** Convert the antlr exceptions to drools parser exceptions */
private void makeErrorList(final DRLParser parser) {
for ( final DroolsParserException recogErr : lexer.getErrors() ) {
final ParserError err = new ParserError( recogErr.getMessage(),
recogErr.getLineNumber(),
recogErr.getColumn() );
this.results.add( err );
}
for ( final DroolsParserException recogErr : parser.getErrors() ) {
final ParserError err = new ParserError( recogErr.getMessage(),
recogErr.getLineNumber(),
recogErr.getColumn() );
this.results.add( err );
}
}
/**
* @return An instance of a RuleParser should you need one (most folks will
* not).
*/
private DRLParser getParser(final String text) {
lexer = new DRLLexer( new ANTLRStringStream( text ) );
DRLParser parser = new DRLParser( new CommonTokenStream( lexer ));
parser.setTreeAdaptor( new DroolsTreeAdaptor() );
return parser;
}
private DRLParser getParser(final Reader reader) {
try {
lexer = new DRLLexer( new ANTLRReaderStream( reader ) );
DRLParser parser = new DRLParser( new CommonTokenStream( lexer ));
parser.setTreeAdaptor( new DroolsTreeAdaptor() );
return parser;
} catch ( final Exception e ) {
throw new RuntimeException( "Unable to parser Reader",
e );
}
}
private DRLParser getParser(final InputStream is) {
try {
lexer = new DRLLexer( new ANTLRInputStream( is ) );
DRLParser parser = new DRLParser( new CommonTokenStream( lexer ));
parser.setTreeAdaptor( new DroolsTreeAdaptor() );
return parser;
} catch ( final Exception e ) {
throw new RuntimeException( "Unable to parser Reader",
e );
}
}
public Location getLocation() {
return this.location;
}
public DefaultExpanderResolver getDefaultResolver(final Reader dsl) throws DroolsParserException {
DefaultExpanderResolver resolver;
try {
resolver = new DefaultExpanderResolver( dsl );
} catch ( final IOException e ) {
throw new DroolsParserException( "Error parsing the DSL.",
e );
}
return resolver;
}
public List<DroolsSentence> getEditorSentences() {
return editorSentences;
}
}