/*
* Copyright (C) 2009 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.*;
import org.parboiled.errors.ActionError;
import org.parboiled.errors.ActionException;
import org.parboiled.matchervisitors.MatcherVisitor;
import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.List;
/**
* A {@link org.parboiled.matchers.Matcher} that not actually matches input but runs a given parser {@link Action}.
*/
public class ActionMatcher extends AbstractMatcher {
public final Action action;
public final List<ContextAware> contextAwares = new ArrayList<ContextAware>();
public final boolean skipInPredicates;
public ActionMatcher(@NotNull Action action) {
this.action = action;
skipInPredicates = action instanceof SkippableAction && ((SkippableAction) action).skipInPredicates();
// check whether the action is a synthetic class generated by parboiled transformation
// if so it will take care of context management itself and we can return immediately
if (action.getClass().isSynthetic()) return;
if (action instanceof ContextAware) {
contextAwares.add((ContextAware) action);
}
// in order to make anonymous inner classes and other member classes work seamlessly
// we collect the synthetic references to the outer parent classes and inform them of
// the current parsing context if they implement ContextAware
for (Field field : action.getClass().getDeclaredFields()) {
if (field.isSynthetic() && ContextAware.class.isAssignableFrom(field.getType())) {
field.setAccessible(true);
try {
ContextAware contextAware = (ContextAware) field.get(action);
if (contextAware != null) contextAwares.add(contextAware);
} catch (IllegalAccessException e) {
// ignore
} finally {
field.setAccessible(false);
}
}
}
}
@Override
public MatcherContext getSubContext(MatcherContext context) {
MatcherContext subContext = context.getBasicSubContext();
subContext.setMatcher(this);
// if the subcontext contains match data we use the existing subcontext without reinitializing
// this way we can access the match data of the previous match from this action
return subContext.getCurrentIndex() > 0 ? subContext : context.getSubContext(this);
}
@SuppressWarnings({"unchecked"})
public <V> boolean match(@NotNull MatcherContext<V> context) {
if (skipInPredicates && context.inPredicate()) return true;
// actions need to run in the parent context
MatcherContext parentContext = context.getParent();
if (!contextAwares.isEmpty()) {
for (ContextAware contextAware : contextAwares) {
contextAware.setContext(parentContext);
}
}
try {
Object valueStackSnapshot = context.getValueStack().takeSnapshot();
if (!action.run(parentContext)) {
// failing actions are not allowed to change the ValueStack
context.getValueStack().restoreSnapshot(valueStackSnapshot);
return false;
}
// since we initialize the actions own context only partially in getSubContext(MatcherContext)
// (in order to be able to still access the previous subcontexts fields in action expressions)
// we need to make sure to not accidentally advance the current index of our parent with some old
// index from a previous subcontext, so we explicitly set the marker here
context.setCurrentIndex(parentContext.getCurrentIndex());
return true;
} catch (ActionException e) {
context.getParseErrors().add(new ActionError(context.getInputBuffer(), context.getCurrentIndex(),
e.getMessage(), context.getPath(), e));
return false;
}
}
@Override
public Rule suppressNode() {
return this; // actions are already "suppressNode"
}
public <R> R accept(@NotNull MatcherVisitor<R> visitor) {
return visitor.visit(this);
}
}