org.apache.avro.io.parsing.SkipParser Maven / Gradle / Ivy
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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
*
* https://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.avro.io.parsing;
import java.io.IOException;
/**
* A parser that capable of skipping as well read and write. This class is used
* by decoders who (unlink encoders) are required to implement methods to skip.
*/
public class SkipParser extends Parser {
/**
* The clients implement this interface to skip symbols and actions.
*/
public interface SkipHandler {
/**
* Skips the action at the top of the stack.
*/
void skipAction() throws IOException;
/**
* Skips the symbol at the top of the stack.
*/
void skipTopSymbol() throws IOException;
}
private final SkipHandler skipHandler;
public SkipParser(Symbol root, ActionHandler symbolHandler, SkipHandler skipHandler) throws IOException {
super(root, symbolHandler);
this.skipHandler = skipHandler;
}
/**
* Skips data by calling skipXyz or readXyz methods on
* this, until the parser stack reaches the target level.
*/
public final void skipTo(int target) throws IOException {
outer: while (target < pos) {
Symbol top = stack[pos - 1];
while (top.kind != Symbol.Kind.TERMINAL) {
if (top.kind == Symbol.Kind.IMPLICIT_ACTION || top.kind == Symbol.Kind.EXPLICIT_ACTION) {
skipHandler.skipAction();
} else {
--pos;
pushProduction(top);
}
continue outer;
}
skipHandler.skipTopSymbol();
}
}
/**
* Skips the repeater at the top the stack.
*/
public final void skipRepeater() throws IOException {
int target = pos;
Symbol repeater = stack[--pos];
assert repeater.kind == Symbol.Kind.REPEATER;
pushProduction(repeater);
skipTo(target);
}
/**
* Pushes the given symbol on to the skip and skips it.
*
* @param symToSkip The symbol that should be skipped.
*/
public final void skipSymbol(Symbol symToSkip) throws IOException {
int target = pos;
pushSymbol(symToSkip);
skipTo(target);
}
}