org.teavm.common.ByteArrayAsyncInputStream Maven / Gradle / Ivy

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/*
 *  Copyright 2022 Alexey Andreev.
 *
 *  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.teavm.common;

import java.util.function.Supplier;

public class ByteArrayAsyncInputStream implements AsyncInputStream {
    private byte[] data;
    private int ptr;
    private CompletablePromise promise;
    private byte[] target;
    private int offset;
    private int count;
    private Throwable errorOccurred;

    public ByteArrayAsyncInputStream(byte[] data) {
        this.data = data;
    }

    @Override
    public Promise skip(int amount) {
        promise = new CompletablePromise<>();
        count = amount;
        return promise;
    }

    @Override
    public Promise read(byte[] buffer, int offset, int count) {
        promise = new CompletablePromise<>();
        this.target = buffer;
        this.offset = offset;
        this.count = count;
        return promise;
    }

    public void readFully(Supplier> command) {
        Promise.runNow(() -> {
            command.get().catchError(e -> {
                errorOccurred = e;
                throw new RuntimeException(e);
            });
            while (promise != null) {
                var p = promise;
                count = Math.min(count, data.length - ptr);
                promise = null;
                if (target != null) {
                    System.arraycopy(data, ptr, target, offset, count);
                    target = null;
                }
                ptr += count;
                if (count == 0) {
                    count = -1;
                }
                p.complete(count);
            }
        });
        var e = errorOccurred;
        errorOccurred = null;
        if (e != null) {
            throw new RuntimeException(e);
        }
    }
}