/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.catalina.ssi;
import java.io.PrintWriter;
import java.text.ParseException;
/**
* SSI command that handles all conditional directives.
*/
public class SSIConditional implements SSICommand {
@Override
public long process(SSIMediator ssiMediator, String commandName, String[] paramNames, String[] paramValues,
PrintWriter writer) throws SSIStopProcessingException {
// Assume anything using conditionals was modified by it
long lastModified = System.currentTimeMillis();
// Retrieve the current state information
SSIConditionalState state = ssiMediator.getConditionalState();
if ("if".equalsIgnoreCase(commandName)) {
// Do nothing if we are nested in a false branch
// except count it
if (state.processConditionalCommandsOnly) {
state.nestingCount++;
return lastModified;
}
state.nestingCount = 0;
// Evaluate the expression
if (evaluateArguments(paramNames, paramValues, ssiMediator)) {
// No more branches can be taken for this if block
state.branchTaken = true;
} else {
// Do not process this branch
state.processConditionalCommandsOnly = true;
state.branchTaken = false;
}
} else if ("elif".equalsIgnoreCase(commandName)) {
// No need to even execute if we are nested in
// a false branch
if (state.nestingCount > 0) {
return lastModified;
}
// If a branch was already taken in this if block
// then disable output and return
if (state.branchTaken) {
state.processConditionalCommandsOnly = true;
return lastModified;
}
// Evaluate the expression
if (evaluateArguments(paramNames, paramValues, ssiMediator)) {
// Turn back on output and mark the branch
state.processConditionalCommandsOnly = false;
state.branchTaken = true;
} else {
// Do not process this branch
state.processConditionalCommandsOnly = true;
state.branchTaken = false;
}
} else if ("else".equalsIgnoreCase(commandName)) {
// No need to even execute if we are nested in
// a false branch
if (state.nestingCount > 0) {
return lastModified;
}
// If we've already taken another branch then
// disable output otherwise enable it.
state.processConditionalCommandsOnly = state.branchTaken;
// And in any case, it's safe to say a branch
// has been taken.
state.branchTaken = true;
} else if ("endif".equalsIgnoreCase(commandName)) {
// If we are nested inside a false branch then pop out
// one level on the nesting count
if (state.nestingCount > 0) {
state.nestingCount--;
return lastModified;
}
// Turn output back on
state.processConditionalCommandsOnly = false;
// Reset the branch status for any outer if blocks,
// since clearly we took a branch to have gotten here
// in the first place.
state.branchTaken = true;
} else {
throw new SSIStopProcessingException();
}
return lastModified;
}
/**
* Retrieves the expression from the specified arguments and performs the necessary evaluation steps.
*/
private boolean evaluateArguments(String[] names, String[] values, SSIMediator ssiMediator)
throws SSIStopProcessingException {
String expr = getExpression(names, values);
if (expr == null) {
throw new SSIStopProcessingException();
}
try {
ExpressionParseTree tree = new ExpressionParseTree(expr, ssiMediator);
return tree.evaluateTree();
} catch (ParseException e) {
throw new SSIStopProcessingException();
}
}
/**
* Returns the "expr" if the arg name is appropriate, otherwise returns null.
*/
private String getExpression(String[] paramNames, String[] paramValues) {
if ("expr".equalsIgnoreCase(paramNames[0])) {
return paramValues[0];
}
return null;
}
}