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/*******************************************************************************
* Copyright (c) 2009 - 2010 Cloudsmith Inc. and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Cloudsmith Inc. - initial API and implementation
*******************************************************************************/
package org.eclipse.equinox.p2.metadata.expression;
import java.io.Serializable;
/**
* A simple compiled pattern. It supports two kinds of wildcards. The '*' (any character zero to many times)
* and the '?' (any character exactly one time).
*/
public class SimplePattern implements Serializable, Comparable<SimplePattern> {
private static final long serialVersionUID = -2477990705739062410L;
/**
* Matches the <code>value</code> with the compiled expression. The value
* is considered matching if all characters are matched by the expression. A
* partial match is not enough.
* @param value The value to match
* @return <code>true</code> if the value was a match.
*/
public synchronized boolean isMatch(CharSequence value) {
if (node == null)
node = parse(pattern, 0);
return node.match(value, 0);
}
public String toString() {
return pattern;
}
public int compareTo(SimplePattern o) {
return pattern.compareTo(o.pattern);
}
public boolean equals(Object o) {
return o == this || (o instanceof SimplePattern && ((SimplePattern) o).pattern.equals(pattern));
}
public int hashCode() {
return 3 * pattern.hashCode();
}
private final String pattern;
private transient Node node;
private SimplePattern(String pattern, Node node) {
this.pattern = pattern;
this.node = node;
}
private static class RubberBandNode extends Node {
RubberBandNode(Node next) {
super(next);
}
boolean match(CharSequence value, int pos) {
if (next == null)
return true;
int top = value.length();
while (pos < top) {
if (next.match(value, pos++))
return true;
}
return false;
}
}
private static class AnyCharacterNode extends Node {
AnyCharacterNode(Node next) {
super(next);
}
boolean match(CharSequence value, int pos) {
int top = value.length();
return next == null ? pos + 1 == top : next.match(value, pos + 1);
}
}
private static class ConstantNode extends Node {
final String constant;
ConstantNode(Node next, String constant) {
super(next);
this.constant = constant;
}
boolean match(CharSequence value, int pos) {
int vtop = value.length();
int ctop = constant.length();
if (ctop + pos > vtop)
return false;
for (int idx = 0; idx < ctop; ++idx, ++pos)
if (constant.charAt(idx) != value.charAt(pos))
return false;
return next == null ? true : next.match(value, pos);
}
}
private static abstract class Node {
final Node next;
Node(Node next) {
this.next = next;
}
abstract boolean match(CharSequence value, int pos);
}
public static SimplePattern compile(String pattern) {
if (pattern == null)
throw new IllegalArgumentException("Pattern can not be null"); //$NON-NLS-1$
return new SimplePattern(pattern, null);
}
private static Node parse(String pattern, int pos) {
int top = pattern.length();
StringBuffer bld = null;
Node parsedNode = null;
while (pos < top) {
char c = pattern.charAt(pos);
switch (c) {
case '*' :
parsedNode = new RubberBandNode(parse(pattern, pos + 1));
break;
case '?' :
parsedNode = new AnyCharacterNode(parse(pattern, pos + 1));
break;
case '\\' :
if (++pos == top)
throw new IllegalArgumentException("Pattern ends with escape"); //$NON-NLS-1$
c = pattern.charAt(pos);
// fall through
default :
if (bld == null)
bld = new StringBuffer();
bld.append(c);
++pos;
continue;
}
break;
}
if (bld != null)
parsedNode = new ConstantNode(parsedNode, bld.toString());
return parsedNode;
}
}
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