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/*
 * Licensed to Elasticsearch under one or more contributor
 * license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright
 * ownership. Elasticsearch 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
 *
 *    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.elasticsearch.common.xcontent;

import org.elasticsearch.common.CheckedFunction;

import java.io.IOException;
import java.nio.CharBuffer;
import java.util.List;
import java.util.Map;
import java.util.function.Supplier;

/**
 * Wrapper for a XContentParser that makes a single object/array look like a complete document.
 *
 * The wrapper prevents the parsing logic to consume tokens outside of the wrapped object as well
 * as skipping to the end of the object in case of a parsing error. The wrapper is intended to be
 * used for parsing objects that should be ignored if they are malformed.
 */
public class XContentSubParser implements XContentParser {

    private final XContentParser parser;
    private int level;
    private boolean closed;

    public XContentSubParser(XContentParser parser) {
        this.parser = parser;
        if (parser.currentToken() != Token.START_OBJECT && parser.currentToken() != Token.START_ARRAY) {
            throw new IllegalStateException("The sub parser has to be created on the start of an object or array");
        }
        level = 1;
    }

    @Override
    public XContentType contentType() {
        return parser.contentType();
    }

    @Override
    public Token nextToken() throws IOException {
        if (level > 0) {
            Token token = parser.nextToken();
            if (token == Token.START_OBJECT || token == Token.START_ARRAY) {
                level++;
            } else if (token == Token.END_OBJECT || token == Token.END_ARRAY) {
                level--;
            }
            return token;
        } else {
            return null; // we have reached the end of the wrapped object
        }
    }

    @Override
    public void skipChildren() throws IOException {
        Token token = parser.currentToken();
        if (token != Token.START_OBJECT && token != Token.START_ARRAY) {
            // skip if not starting on an object or an array
            return;
        }
        int backToLevel = level - 1;
        while (nextToken() != null) {
            if (level <= backToLevel) {
                return;
            }
        }
    }

    @Override
    public Token currentToken() {
        return parser.currentToken();
    }

    @Override
    public String currentName() throws IOException {
        return parser.currentName();
    }

    @Override
    public Map map() throws IOException {
        return parser.map();
    }

    @Override
    public Map mapOrdered() throws IOException {
        return parser.mapOrdered();
    }

    @Override
    public Map mapStrings() throws IOException {
        return parser.mapStrings();
    }

    @Override
    public  Map map(
            Supplier> mapFactory, CheckedFunction mapValueParser) throws IOException {
        return parser.map(mapFactory, mapValueParser);
    }

    @Override
    public List