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/*******************************************************************************
* Copyright (c) 2009, 2017 Cloudsmith Inc. and others.
*
* This program and the accompanying materials
* are made available under the terms of the Eclipse Public License 2.0
* which accompanies this distribution, and is available at
* https://www.eclipse.org/legal/epl-2.0/
*
* SPDX-License-Identifier: EPL-2.0
*
* 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).
* @since 2.0
*/
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 boolean isMatch(CharSequence value) {
if (node == null)
node = parse(pattern, 0);
return node.match(value, 0);
}
@Override
public String toString() {
return pattern;
}
@Override
public int compareTo(SimplePattern o) {
return pattern.compareTo(o.pattern);
}
@Override
public boolean equals(Object o) {
return o == this || (o instanceof SimplePattern && ((SimplePattern) o).pattern.equals(pattern));
}
@Override
public int hashCode() {
return 3 * pattern.hashCode();
}
private final String pattern;
private transient Node node;
private SimplePattern(String pattern) {
this.pattern = pattern;
}
static class AllNode extends Node {
@Override
boolean match(CharSequence value, int pos) {
return true;
}
}
static class RubberBandNode extends Node {
final Node next;
RubberBandNode(Node next) {
this.next = next;
}
@Override
boolean match(CharSequence value, int pos) {
int top = value.length();
String ending = next.getEndingConstant();
if (ending != null) {
// value must end with this constant. It will be faster
// to scan backwards from the end.
int clen = ending.length();
if (clen > top - pos)
return false;
while (clen > 0)
if (ending.charAt(--clen) != value.charAt(--top))
return false;
return true;
}
while (pos < top) {
if (next.match(value, pos++))
return true;
}
return false;
}
}
static class AnyCharacterNode extends Node {
final Node next;
AnyCharacterNode(Node next) {
this.next = next;
}
@Override
boolean match(CharSequence value, int pos) {
int top = value.length();
return next == null ? pos + 1 == top : next.match(value, pos + 1);
}
}
static class EndConstantNode extends Node {
final String constant;
EndConstantNode(String constant) {
this.constant = constant;
}
@Override
boolean match(CharSequence value, int pos) {
int max = constant.length() + pos;
int top = value.length();
if (top != max)
return false;
int idx = 0;
while (pos < max)
if (value.charAt(pos++) != constant.charAt(idx++))
return false;
return true;
}
@Override
String getEndingConstant() {
return constant;
}
}
static class ConstantNode extends Node {
final Node next;
final String constant;
ConstantNode(Node next, String constant) {
this.next = next;
this.constant = constant;
}
@Override
boolean match(CharSequence value, int pos) {
int max = constant.length() + pos;
int top = value.length();
if (top < max)
return false;
int idx = 0;
while (pos < max)
if (value.charAt(pos++) != constant.charAt(idx++))
return false;
return next == null ? (pos == top) : next.match(value, pos);
}
}
static abstract class Node {
abstract boolean match(CharSequence value, int pos);
String getEndingConstant() {
return null;
}
}
public static SimplePattern compile(String pattern) {
if (pattern == null)
throw new IllegalArgumentException("Pattern can not be null"); //$NON-NLS-1$
return new SimplePattern(pattern);
}
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 '*' :
++pos;
parsedNode = pos == top ? new AllNode() : new RubberBandNode(parse(pattern, pos));
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) {
String constant = bld.toString();
parsedNode = parsedNode == null ? new EndConstantNode(constant) : new ConstantNode(parsedNode, constant);
}
return parsedNode;
}
}
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