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/*
* 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.el.util;
import java.security.AccessController;
import java.security.PrivilegedAction;
public class Validation {
// Java keywords, boolean literals & the null literal in alphabetical order
private static final String invalidIdentifiers[] = { "abstract", "assert",
"boolean", "break", "byte", "case", "catch", "char", "class", "const",
"continue", "default", "do", "double", "else", "enum", "extends",
"false", "final", "finally", "float", "for", "goto", "if", "implements",
"import", "instanceof", "int", "interface", "long", "native", "new",
"null", "package", "private", "protected", "public", "return", "short",
"static", "strictfp", "super", "switch", "synchronized", "this",
"throw", "throws", "transient", "true", "try", "void", "volatile",
"while" };
private static final boolean IS_SECURITY_ENABLED =
(System.getSecurityManager() != null);
private static final boolean SKIP_IDENTIFIER_CHECK;
static {
String skipIdentifierCheckStr;
if (IS_SECURITY_ENABLED) {
skipIdentifierCheckStr = AccessController.doPrivileged(
new PrivilegedAction<String>(){
@Override
public String run() {
return System.getProperty(
"org.apache.el.parser.SKIP_IDENTIFIER_CHECK",
"false");
}
}
);
} else {
skipIdentifierCheckStr = System.getProperty(
"org.apache.el.parser.SKIP_IDENTIFIER_CHECK", "false");
}
SKIP_IDENTIFIER_CHECK = Boolean.parseBoolean(skipIdentifierCheckStr);
}
private Validation() {
// Utility class. Hide default constructor
}
/**
* Test whether the argument is a Java identifier.
*/
public static boolean isIdentifier(String key) {
if (SKIP_IDENTIFIER_CHECK) {
return true;
}
// Should not be the case but check to be sure
if (key == null || key.length() == 0) {
return false;
}
// Check the list of known invalid values
int i = 0;
int j = invalidIdentifiers.length;
while (i < j) {
int k = (i + j) >>> 1; // Avoid overflow
int result = invalidIdentifiers[k].compareTo(key);
if (result == 0) {
return false;
}
if (result < 0) {
i = k + 1;
} else {
j = k;
}
}
// Check the start character that has more restrictions
if (!Character.isJavaIdentifierStart(key.charAt(0))) {
return false;
}
// Check each remaining character used is permitted
for (int idx = 1; idx < key.length(); idx++) {
if (!Character.isJavaIdentifierPart(key.charAt(idx))) {
return false;
}
}
return true;
}
}
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