com.google.template.soy.sharedpasses.render.CountingFlushableAppendable.java Source code

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Here is the source code for com.google.template.soy.sharedpasses.render.CountingFlushableAppendable.java

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/*
 * Copyright 2014 Google 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 com.google.template.soy.sharedpasses.render;

import com.google.common.base.Preconditions;
import com.google.template.soy.data.SoyFutureValueProvider.FutureBlockCallback;

import java.io.Flushable;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * Counts the characters that have been appended to the wrapped appenable since it was last flushed.
 */
public final class CountingFlushableAppendable implements Appendable, Flushable, FutureBlockCallback {

    private static final Logger logger = Logger.getLogger(CountingFlushableAppendable.class.getName());

    private int count;
    private final Appendable appendable;
    private final Flushable flushable;

    public CountingFlushableAppendable(Appendable appendable) {
        Preconditions.checkState(appendable instanceof Flushable);
        this.appendable = appendable;
        this.flushable = (Flushable) appendable;
    }

    CountingFlushableAppendable(Appendable appendable, Flushable flushable) {
        this.appendable = appendable;
        this.flushable = flushable;
    }

    public int getAppendedCountSinceLastFlush() {
        return count;
    }

    @Override
    public Appendable append(CharSequence csq) throws IOException {
        count += csq.length();
        return appendable.append(csq);
    }

    @Override
    public Appendable append(CharSequence csq, int start, int end) throws IOException {
        count += end - start;
        return appendable.append(csq, start, end);
    }

    @Override
    public Appendable append(char c) throws IOException {
        count += 1;
        return appendable.append(c);
    }

    @Override
    public void flush() throws IOException {
        count = 0;
        flushable.flush();
    }

    /**
     * Soy is about to block on a future. Flush the output stream if there is anything to flush,
     * so we use the time we are blocking to transfer as many bytes as possible.
     */
    @Override
    public void beforeBlock() {
        if (count > 0) {
            try {
                flush();
            } catch (IOException e) {
                logger.log(Level.SEVERE, "Flush from soy failed", e);
            }
        }
    }
}