/*
* Copyright 1999-2004 The Apache Software Foundation.
*
* 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.
*/
package org.apache.cocoon.components.treeprocessor.variables;
import org.apache.avalon.framework.activity.Disposable;
import org.apache.avalon.framework.component.ComponentManager;
import org.apache.avalon.framework.configuration.ConfigurationException;
import org.apache.avalon.framework.service.ServiceException;
import org.apache.avalon.framework.service.ServiceManager;
import org.apache.avalon.framework.service.ServiceSelector;
import org.apache.avalon.framework.service.WrapperServiceManager;
import org.apache.avalon.framework.thread.ThreadSafe;
import org.apache.cocoon.components.modules.input.InputModule;
import org.apache.cocoon.components.treeprocessor.InvokeContext;
import org.apache.cocoon.sitemap.PatternException;
import org.apache.commons.lang.builder.HashCodeBuilder;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Stack;
/**
* Prepared implementation of {@link VariableResolver} for fast evaluation.
*
* @author <a href="mailto:uv@upaya.co.uk">Upayavira</a>
* @version CVS $Id: PreparedVariableResolver.java 367127 2006-01-08 23:26:58Z antonio $
*/
final public class PreparedVariableResolver extends VariableResolver implements Disposable {
private ServiceManager manager;
private ServiceSelector selector;
protected List tokens;
protected boolean needsMapStack;
private static final int OPEN = -2;
private static final int CLOSE = -3;
private static final int COLON = -4;
private static final int TEXT = -5;
private static final int EXPR = -7;
private static final int SITEMAP_VAR = -9;
private static final int THREADSAFE_MODULE = -10;
private static final int STATEFUL_MODULE = -11;
private static final int ROOT_SITEMAP_VARIABLE = 0;
private static final int ANCHOR_VAR = -1;
private static Token COLON_TOKEN = new Token(COLON);
private static Token OPEN_TOKEN = new Token(OPEN);
private static Token CLOSE_TOKEN = new Token(CLOSE);
private static Token EMPTY_TOKEN = new Token(EXPR);
/**
* @deprecated use the version with <code>ServiceManager</service>
*/
public PreparedVariableResolver(String expr, ComponentManager manager) throws PatternException {
this(expr, new WrapperServiceManager(manager));
}
public PreparedVariableResolver(String expr, ServiceManager manager) throws PatternException {
super(expr);
this.manager = manager;
this.tokens = new ArrayList();
VariableExpressionTokenizer.tokenize(expr, new VariableExpressionTokenizer.TokenReciever() {
public void addToken(int type, String value) throws PatternException {
switch (type) {
case VariableExpressionTokenizer.TokenReciever.COLON:
tokens.add(COLON_TOKEN);
break;
case VariableExpressionTokenizer.TokenReciever.OPEN:
tokens.add(OPEN_TOKEN);
break;
case VariableExpressionTokenizer.TokenReciever.CLOSE:
tokens.add(CLOSE_TOKEN);
break;
case VariableExpressionTokenizer.TokenReciever.TEXT:
tokens.add(new Token(value));
break;
case VariableExpressionTokenizer.TokenReciever.MODULE:
Token token;
if (value.equals("sitemap")) {
// Explicit prefix for sitemap variable
needsMapStack = true;
token = new Token(SITEMAP_VAR);
} else if (value.startsWith("#")) {
// anchor syntax refering to a name result level
needsMapStack = true;
token = new Token(ANCHOR_VAR, value.substring(1));
} else {
// Module used
token = getNewModuleToken(value);
}
tokens.add(token);
break;
case VariableExpressionTokenizer.TokenReciever.VARIABLE:
needsMapStack = true;
tokens.add(getNewVariableToken(value));
break;
default:
throw new IllegalArgumentException("Unknown token type: " + type);
}
}
});
}
private Token getNewVariableToken(String variable) {
if (variable.startsWith("/")) {
return new Token(ROOT_SITEMAP_VARIABLE, variable.substring(1));
} else {
// Find level
int level = 1; // Start at 1 since it will be substracted from list.size()
int pos = 0;
while (variable.startsWith("../", pos)) {
level++;
pos += "../".length();
}
return new Token(level, variable.substring(pos));
}
}
private Token getNewModuleToken(String moduleName) throws PatternException {
if (this.selector == null) {
try {
// First access to a module : lookup selector
this.selector = (ServiceSelector) this.manager.lookup(InputModule.ROLE + "Selector");
} catch(ServiceException ce) {
throw new PatternException("Cannot access input modules selector", ce);
}
}
// Get the module
InputModule module;
try {
module = (InputModule) this.selector.select(moduleName);
} catch (ServiceException e) {
throw new PatternException("Cannot get module named '" + moduleName +
"' in expression '" + this.originalExpr + "'", e);
}
Token token;
// Is this module threadsafe ?
if (module instanceof ThreadSafe) {
token = new Token(THREADSAFE_MODULE, module);
} else {
// Stateful module : release it and get a new one each time
this.selector.release(module);
token = new Token(STATEFUL_MODULE, moduleName);
}
return token;
}
public final String resolve(InvokeContext context, Map objectModel) throws PatternException {
List mapStack = null; // get the stack only when necessary - lazy inside the loop
int stackSize = 0;
if (needsMapStack) {
if (context == null) {
throw new PatternException("Need an invoke context to resolve " + this);
}
mapStack = context.getMapStack();
stackSize = mapStack.size();
}
Stack stack = new Stack();
for (Iterator i = tokens.iterator(); i.hasNext();) {
Token token = (Token) i.next();
Token last;
switch (token.getType()){
case TEXT:
if (stack.empty()) {
stack.push(new Token(EXPR, token.getStringValue()));
} else {
last = (Token)stack.peek();
if (last.hasType(EXPR)) {
last.merge(token);
} else {
stack.push(new Token(EXPR, token.getStringValue()));
}
}
break;
case CLOSE:
Token expr = (Token)stack.pop();
Token lastButOne = (Token)stack.pop();
Token result;
if (expr.hasType(COLON)) { // i.e. nothing was specified after the colon
stack.pop(); // Pop the OPEN
result = processModule(lastButOne, EMPTY_TOKEN, objectModel, context, mapStack, stackSize);
} else if (lastButOne.hasType(COLON)) {
Token module = (Token)stack.pop();
stack.pop(); // Pop the OPEN
result = processModule(module, expr, objectModel, context, mapStack, stackSize);
} else {
result = processVariable(expr, mapStack, stackSize);
}
if (stack.empty()) {
stack.push(result);
} else {
last = (Token)stack.peek();
if (last.hasType(EXPR)) {
last.merge(result);
} else {
stack.push(result);
}
}
break;
case OPEN:
case COLON:
case ANCHOR_VAR:
case THREADSAFE_MODULE:
case STATEFUL_MODULE:
case ROOT_SITEMAP_VARIABLE:
default: {
stack.push(token);
break;
}
}
}
if (stack.size() !=1) {
throw new PatternException("Evaluation error in expression: " + originalExpr);
}
return ((Token)stack.pop()).getStringValue();
}
private Token processModule(Token module, Token expr, Map objectModel, InvokeContext context, List mapStack, int stackSize) throws PatternException {
int type = module.getType();
if (type == ANCHOR_VAR) {
Map levelResult = context.getMapByAnchor(module.getStringValue());
if (levelResult == null) {
throw new PatternException("Error while evaluating '" + this.originalExpr +
"' : no anchor '" + String.valueOf(module.getStringValue()) + "' found in context");
}
Object result = levelResult.get(expr.getStringValue());
return new Token(EXPR, result==null ? "" : result.toString());
} else if (type == THREADSAFE_MODULE) {
try {
InputModule im = module.getModule();
Object result = im.getAttribute(expr.getStringValue(), null, objectModel);
return new Token(EXPR, result==null ? "" : result.toString());
} catch(ConfigurationException confEx) {
throw new PatternException("Cannot get variable '" + expr.getStringValue() +
"' in expression '" + this.originalExpr + "'", confEx);
}
} else if (type == STATEFUL_MODULE) {
InputModule im = null;
String moduleName = module.getStringValue();
try {
im = (InputModule) this.selector.select(moduleName);
Object result = im.getAttribute(expr.getStringValue(), null, objectModel);
return new Token(EXPR, result==null ? "" : result.toString());
} catch(ServiceException e) {
throw new PatternException("Cannot get module '" + moduleName +
"' in expression '" + this.originalExpr + "'", e);
} catch(ConfigurationException confEx) {
throw new PatternException("Cannot get variable '" + expr.getStringValue() +
"' in expression '" + this.originalExpr + "'", confEx);
} finally {
this.selector.release(im);
}
} else if (type == SITEMAP_VAR) {
// Prefixed sitemap variable must be parsed at runtime
String variable = expr.getStringValue();
Token token;
if (variable.startsWith("/")) {
token = new Token(ROOT_SITEMAP_VARIABLE, variable.substring(1));
} else {
// Find level
int level = 1; // Start at 1 since it will be substracted from list.size()
int pos = 0;
while (variable.startsWith("../", pos)) {
level++;
pos += "../".length();
}
token = new Token(level, variable.substring(pos));
}
return processVariable(token, mapStack, stackSize);
} else {
throw new PatternException("Unknown token type: " + expr.getType());
}
}
private Token processVariable(Token expr, List mapStack, int stackSize) throws PatternException {
int type = expr.getType();
String value = expr.getStringValue();
if (type == ROOT_SITEMAP_VARIABLE) {
Object result = ((Map)mapStack.get(0)).get(value);
return new Token(EXPR, result==null ? "" : result.toString());
} else {
// relative sitemap variable
if (type > stackSize) {
throw new PatternException("Error while evaluating '" + this.originalExpr +
"' : not so many levels");
}
Object result = ((Map)mapStack.get(stackSize - type)).get(value);
return new Token(EXPR, result==null ? "" : result.toString());
}
}
public final void dispose() {
if (this.selector != null) {
for (Iterator i = tokens.iterator(); i.hasNext();) {
Token token = (Token)i.next();
if (token.hasType(THREADSAFE_MODULE)) {
InputModule im = token.getModule();
this.selector.release(im);
}
}
this.manager.release(this.selector);
this.selector = null;
this.manager = null;
}
}
private static class Token {
private Object value;
private int type;
public Token(int type) {
if (type==EXPR) {
this.value="";
} else {
this.value = null;
}
this.type = type;
}
public Token(int type, String value) {
this.value = value;
this.type = type;
}
public Token(int type, InputModule module) {
this.value = module;
this.type = type;
}
public Token(String value) {
this.type = TEXT;
this.value = value;
}
public int getType() {
return type;
}
public String getStringValue() {
if (value instanceof String) {
return (String)this.value;
} else {
return null;
}
}
public boolean hasType(int type){
return this.type == type;
}
public boolean equals(Object o) {
if (o instanceof Token) {
return ((Token)o).hasType(this.type);
} else {
return false;
}
}
public int hashCode() {
return new HashCodeBuilder().
append(value).
append(this.type).
toHashCode();
}
public void merge(Token newToken) {
this.value = this.value + newToken.getStringValue();
}
public InputModule getModule() {
if (value instanceof InputModule) {
return (InputModule)value;
} else {
return null;
}
}
}
}