io.reactivex.netty.protocol.text.StringLineDecoder.java Source code

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Here is the source code for io.reactivex.netty.protocol.text.StringLineDecoder.java

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/*
 * Copyright 2014 Netflix, Inc.
 *
 * 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 io.reactivex.netty.protocol.text;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.ReplayingDecoder;

import java.util.List;

/**
 * A decoder that breaks an incoming {@link ByteBuf} into a list of strings delimited by a new line as specified by
 * {@link #isLineDelimiter(char)}
 */
class StringLineDecoder extends ReplayingDecoder<StringLineDecoder.State> {

    public enum State {
        NEW_LINE, END_OF_LINE
    }

    public StringLineDecoder() {
        super(State.NEW_LINE);
    }

    @Override
    protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
        switch (state()) {
        case NEW_LINE:
            String line = readFullLine(in);

            // Immediately checkpoint the progress so that replaying decoder
            // will not start over from the beginning of the line when buffer overflows
            checkpoint();

            out.add(line);
            break;
        case END_OF_LINE:
            skipLineDelimiters(in);
            break;
        }
    }

    private String readFullLine(ByteBuf in) {
        StringBuilder line = new StringBuilder();

        for (;;) {
            char c = (char) in.readByte();
            if (isLineDelimiter(c)) {
                checkpoint(State.END_OF_LINE);
                return line.toString();
            }

            line.append(c);
        }
    }

    private void skipLineDelimiters(ByteBuf in) {
        for (;;) {
            char c = (char) in.readByte();
            if (isLineDelimiter(c)) {
                continue;
            }

            // Leave the reader index at the first letter of the next line, if any
            in.readerIndex(in.readerIndex() - 1);
            checkpoint(State.NEW_LINE);
            break;
        }
    }

    public static boolean isLineDelimiter(char c) {
        return c == '\r' || c == '\n';
    }
}