/**
* LOGBack: the generic, reliable, fast and flexible logging framework.
*
* Copyright (C) 1999-2006, QOS.ch
*
* This library is free software, you can redistribute it and/or modify it under
* the terms of the GNU Lesser General Public License as published by the Free
* Software Foundation.
*/
package ch.qos.logback.core.joran.spi;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Stack;
import java.util.Vector;
import org.xml.sax.Attributes;
import org.xml.sax.Locator;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
import org.xml.sax.helpers.DefaultHandler;
import ch.qos.logback.core.joran.action.Action;
import ch.qos.logback.core.joran.action.ImplicitAction;
/**
* <id>Interpreter</id> is Joran's main driving class. It extends SAX
* {@link org.xml.sax.helpers.DefaultHandler DefaultHandler} which invokes
* various {@link Action actions} according to predefined patterns.
*
* <p>
* Patterns are kept in a {@link RuleStore} which is programmed to store and
* then later produce the applicable actions for a given pattern.
*
* <p>
* The pattern corresponding to a top level <a> element is the string
* <id>"a"</id>.
*
* <p>
* The pattern corresponding to an element <b> embedded within a top level
* <a> element is the string <id>"a/b"</id>.
*
* <p>
* The pattern corresponding to an <b> and any level of nesting is
* "*/b. Thus, the * character placed at the beginning of a pattern
* serves as a wildcard for the level of nesting.
*
* Conceptually, this is very similar to the API of commons-digester. Joran
* offers several small advantages. First and foremost, it offers support for
* implicit actions which result in a significant leap in flexibility. Second,
* in our opinion better error reporting capability. Third, it is self-reliant.
* It does not depend on other APIs, in particular commons-logging which is too
* unreliable. Last but not least, Joran is quite tiny and is expected to remain
* so.
*
* @author Ceki Gülcuü
*
*/
public class Interpreter extends DefaultHandler {
private static List EMPTY_LIST = new Vector(0);
private RuleStore ruleStore;
private ExecutionContext ec;
private ArrayList<ImplicitAction> implicitActions;
Pattern pattern;
Locator locator;
/**
* The <id>actionListStack</id> contains a list of actions that are executing
* for the given XML element.
*
* A list of actions is pushed by the {link #startElement} and popped by
* {@link #endElement}.
*
*/
Stack<List> actionListStack;
/**
* If the skip nested is set, then we skip all its nested elements until it is
* set back to null at when the element's end is reached.
*/
Pattern skip = null;
public Interpreter(RuleStore rs) {
ruleStore = rs;
ec = new ExecutionContext(this);
implicitActions = new ArrayList<ImplicitAction>(3);
pattern = new Pattern();
actionListStack = new Stack<List>();
}
public ExecutionContext getExecutionContext() {
return ec;
}
public void startDocument() {
}
public void startElement(String namespaceURI, String localName, String qName,
Attributes atts) {
String tagName = getTagName(localName, qName);
System.out.println("startElement [" + tagName + "]");
// LogLog.debug("in startElement <" + tagName + ">");
pattern.push(tagName);
List applicableActionList = getApplicableActionList(pattern, atts);
if (applicableActionList != null) {
actionListStack.add(applicableActionList);
callBeginAction(applicableActionList, tagName, atts);
} else {
actionListStack.add(EMPTY_LIST);
String errMsg = "no applicable action for <" + tagName
+ ">, current pattern is [" + pattern + "]";
ec.addError(errMsg);
}
}
public void characters(char[] ch, int start, int length) {
List applicableActionList = (List) actionListStack.peek();
String body = new String(ch, start, length);
if(body != null) {
body = body.trim();
}
if(body.length() > 0) {
System.out.println("calling body method with ["+body+ "]");
callBodyAction(applicableActionList, body);
}
}
public void endElement(String namespaceURI, String localName, String qName) {
List applicableActionList = (List) actionListStack.pop();
// System.out.println("endElement ["+getTagName(localName, qName)+"]");
if (skip != null) {
// System.err.println("In End, pattern is "+pattern+", skip pattern
// "+skip);
if (skip.equals(pattern)) {
// ec.addInfo("Normal processing will continue with the next element.
// Current pattern is <"+ pattern+">", this);
skip = null;
} else {
// getLogger().debug("Skipping invoking end() method for <{}>.",
// pattern);
}
} else if (applicableActionList != EMPTY_LIST) {
callEndAction(applicableActionList, getTagName(localName, qName));
}
// given that we always push, we must also pop the pattern
pattern.pop();
}
public Locator getLocator() {
return locator;
}
public void setDocumentLocator(Locator l) {
locator = l;
}
String getTagName(String localName, String qName) {
String tagName = localName;
if ((tagName == null) || (tagName.length() < 1)) {
tagName = qName;
}
return tagName;
}
public void addImplicitAction(ImplicitAction ia) {
implicitActions.add(ia);
}
/**
* Check if any implicit actions are applicable. As soon as an applicable
* action is found, it is returned. Thus, the returned list will have at most
* one element.
*/
List lookupImplicitAction(Pattern pattern, Attributes attributes,
ExecutionContext ec) {
int len = implicitActions.size();
for (int i = 0; i < len; i++) {
ImplicitAction ia = (ImplicitAction) implicitActions.get(i);
if (ia.isApplicable(pattern, attributes, ec)) {
List<Action> actionList = new ArrayList<Action>(1);
actionList.add(ia);
return actionList;
}
}
return null;
}
/**
* Return the list of applicable patterns for this
*/
List getApplicableActionList(Pattern pattern, Attributes attributes) {
List applicableActionList = ruleStore.matchActions(pattern);
// logger.debug("set of applicable patterns: " + applicableActionList);
if (applicableActionList == null) {
applicableActionList = lookupImplicitAction(pattern, attributes, ec);
}
return applicableActionList;
}
void callBeginAction(List applicableActionList, String tagName,
Attributes atts) {
if (applicableActionList == null) {
return;
}
if (skip != null) {
// getLogger().debug("Skipping invoking begin() method for <{}>.",
// pattern);
return;
}
Iterator i = applicableActionList.iterator();
while (i.hasNext()) {
Action action = (Action) i.next();
// now let us invoke the action. We catch and report any eventual
// exceptions
try {
action.begin(ec, tagName, atts);
} catch (ActionException ae) {
switch (ae.getSkipCode()) {
case ActionException.SKIP_CHILDREN:
skip = (Pattern) pattern.clone();
break;
case ActionException.SKIP_SIBLINGS:
skip = (Pattern) pattern.clone();
// pretend the exception came from one level up. This will cause
// all children and following siblings elements to be skipped
skip.pop();
break;
}
// getLogger().info("Skip pattern set to <{}>", skip);
} catch (Exception e) {
skip = (Pattern) pattern.clone();
// getLogger().info("Skip pattern set to <{}>", skip);
ec.addError("Exception in Action for tag <" + tagName + ">", this, e);
}
}
}
void callBodyAction(List applicableActionList, String body) {
if (applicableActionList == null) {
return;
}
Iterator i = applicableActionList.iterator();
while (i.hasNext()) {
Action action = (Action) i.next();
try {
action.body(ec, body);
} catch (ActionException ae) {
ec.addError("Exception in end() methd for action [" + action+ "]", this, ae);
}
}
}
void callEndAction(List applicableActionList, String tagName) {
if (applicableActionList == null) {
return;
}
// logger.debug("About to call end actions on node: <" + localName + ">");
Iterator i = applicableActionList.iterator();
while (i.hasNext()) {
Action action = (Action) i.next();
// now let us invoke the end method of the action. We catch and report
// any eventual exceptions
try {
action.end(ec, tagName);
} catch (ActionException ae) {
switch (ae.getSkipCode()) {
case ActionException.SKIP_CHILDREN:
// after end() is called there can't be any children
break;
case ActionException.SKIP_SIBLINGS:
skip = (Pattern) pattern.clone();
skip.pop();
break;
}
// getLogger().info("Skip pattern set to <{}>", skip);
} catch (Exception e) {
ec.addError("Exception in Action for tag <" + tagName + ">", this, e);
skip = (Pattern) pattern.clone();
skip.pop(); // induce the siblings to be skipped
// getLogger().info("Skip pattern set to <{}>.", skip);
}
}
}
public RuleStore getRuleStore() {
return ruleStore;
}
public void setRuleStore(RuleStore ruleStore) {
this.ruleStore = ruleStore;
}
// /**
// * Call the finish methods for all actions. Unfortunately, the endDocument
// * method is not called in case of errors in the XML document, which
// * makes endDocument() pretty damn useless.
// */
// public void endDocument() {
// Set arrayListSet = ruleStore.getActionSet();
// Iterator iterator = arrayListSet.iterator();
// while(iterator.hasNext()) {
// ArrayList al = (ArrayList) iterator.next();
// for(int i = 0; i < al.size(); i++) {
// Action a = (Action) al.get(i);
// a.endDocument(ec);
// }
// }
// }
public void error(SAXParseException spe) throws SAXException {
ec.addError("Parsing error", this, spe);
ec.addError("Parsing problem on line " + spe.getLineNumber()
+ " and column " + spe.getColumnNumber(), this, spe);
}
public void fatalError(SAXParseException spe) throws SAXException {
ec.addError("Parsing fatal error", this, spe);
ec.addError("Parsing problem on line " + spe.getLineNumber()
+ " and column " + spe.getColumnNumber(), this, spe);
}
public void warning(SAXParseException spe) throws SAXException {
ec.addWarn("Parsing warning", this, spe);
ec.addWarn("Parsing problem on line " + spe.getLineNumber()
+ " and column " + spe.getColumnNumber(), this, spe);
}
public void endPrefixMapping(java.lang.String prefix) {
}
public void ignorableWhitespace(char[] ch, int start, int length) {
}
public void processingInstruction(java.lang.String target,
java.lang.String data) {
}
public void skippedEntity(java.lang.String name) {
}
public void startPrefixMapping(java.lang.String prefix, java.lang.String uri) {
}
// public EntityResolver getEntityResolver() {
// return entityResolver;
// }
//
// public void setEntityResolver(EntityResolver entityResolver) {
// this.entityResolver = entityResolver;
// }
/**
* If a specific entityResolver is set for this Interpreter instance, then we
* use it to resolve entities. Otherwise, we use the default implementation
* offered by the super class.
*
* <p>
* Due to inexplicable voodoo, the original resolveEntity method in
* org.xml.sax.helpers.DefaultHandler declares throwing an IOException,
* whereas the org.xml.sax.helpers.DefaultHandler class included in JDK 1.4
* masks this exception.
*
* <p>
* In order to compile under JDK 1.4, we are forced to mask the IOException as
* well. Since its signatures varies, we cannot call our super class'
* resolveEntity method. We are forced to implement the default behavior
* ourselves, which in this case, is just returning null.
*
*/
// public InputSource resolveEntity(String publicId, String systemId) throws
// SAXException {
// if(entityResolver == null) {
// // the default implementation is to return null
// return null;
// } else {
// try {
// return entityResolver.resolveEntity(publicId, systemId);
// } catch(IOException ioe) {
// // fall back to the default "implementation"
// return null;
// }
// }
// }
}