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.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 = "Unknown error while parsing. This is a bug. Please contact the Development team.";
private final List results = new ArrayList();
private List<DroolsSentence> editorSentences = null;
private Location location = new Location(Location.LOCATION_UNKNOWN);
DescrBuilderTree walker = 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 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(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);
}
/**
* 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 (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 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,
-1, 0);
this.results.add(err);
if (isEditor) {
if (walker == null){
return null;
}
return walker.getPackageDescr();
} else {
throw new DroolsParserException(
GENERIC_ERROR_MESSAGE,
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 Iterator iter = parser.getErrors().iterator(); iter
.hasNext();) {
final DroolsParserException recogErr = (DroolsParserException) iter
.next();
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) {
DRLParser parser = new DRLParser(new CommonTokenStream(new DRLLexer(
new ANTLRStringStream(text))));
parser.setTreeAdaptor(new DroolsTreeAdaptor());
return parser;
}
private DRLParser getParser(final Reader reader) {
try {
DRLParser parser = new DRLParser(new CommonTokenStream(
new DRLLexer(new ANTLRReaderStream(reader))));
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;
}
}