/*
* Copyright (C) 2009-2010 Mathias Doenitz
*
* 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.parboiled.matchers;
import org.jetbrains.annotations.NotNull;
import org.parboiled.MatcherContext;
import org.parboiled.Rule;
import org.parboiled.matchervisitors.MatcherVisitor;
import java.util.List;
/**
* Special wrapping matcher that performs memoization of the last mismatch of the wrapped sub rule.
*/
public class MemoMismatchesMatcher implements Matcher {
private final Matcher inner;
// we use an int field as memoization flag, it has the following semantics
// memo >= 0 : last match failed at position memo
// memo == Integer.MIN_VALUE: this match was either never tried or succeeded the last time it was tried
private int memo = Integer.MIN_VALUE;
public MemoMismatchesMatcher(@NotNull Rule inner) {
this.inner = (Matcher) inner;
}
@SuppressWarnings({"unchecked"})
public <V> boolean match(@NotNull MatcherContext<V> context) {
int pos = context.getCurrentIndex();
if (memo == pos) {
return false;
}
if (inner.match(context)) {
memo = Integer.MIN_VALUE;
return true;
}
memo = pos;
return false;
}
// GraphNode
@NotNull
public List<Matcher> getChildren() {
return inner.getChildren();
}
// Rule
public Rule label(String label) {
return new MemoMismatchesMatcher(inner.label(label));
}
public Rule suppressNode() {
return new MemoMismatchesMatcher(inner.suppressNode());
}
public Rule suppressSubnodes() {
return new MemoMismatchesMatcher(inner.suppressSubnodes());
}
public Rule skipNode() {
return new MemoMismatchesMatcher(inner.skipNode());
}
public Rule memoMismatches() {
return this; // already done
}
// Matcher
public String getLabel() {return inner.getLabel();}
public boolean isNodeSuppressed() {return inner.isNodeSuppressed();}
public boolean areSubnodesSuppressed() {return inner.areSubnodesSuppressed();}
public boolean isNodeSkipped() {return inner.isNodeSkipped();}
public boolean areMismatchesMemoed() { return true; }
public void setTag(Object tagObject) { inner.setTag(tagObject); }
public Object getTag() { return inner.getTag(); }
public MatcherContext getSubContext(MatcherContext context) {
MatcherContext subContext = inner.getSubContext(context);
subContext.setMatcher(this); // we need to inject ourselves here otherwise we get cut out
return subContext;
}
public <R> R accept(@NotNull MatcherVisitor<R> visitor) {return inner.accept(visitor);}
@Override
public String toString() { return inner.toString(); }
/**
* Retrieves the innermost Matcher that is not a MemoMismatchesMatcher.
*
* @param matcher the matcher to unwrap
* @return the given instance if it is not a MemoMismatchesMatcher, otherwise the innermost Matcher
*/
public static Matcher unwrap(Matcher matcher) {
if (matcher instanceof MemoMismatchesMatcher) {
MemoMismatchesMatcher memoMismatchesMatcher = (MemoMismatchesMatcher) matcher;
return unwrap(memoMismatchesMatcher.inner);
}
return matcher;
}
}