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Java 8 Functional interface extentions, collection decorators, I/O interfaces, and assertions
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/*
 * Copyright (C) 2015 fuwjax.org ([email protected])
 *
 * 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.fuwjax.oss.util.io;

import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;
import java.nio.ByteBuffer;
import java.util.PrimitiveIterator.OfInt;
import java.util.Spliterators.AbstractIntSpliterator;
import java.util.function.Consumer;
import java.util.function.IntConsumer;
import java.util.stream.IntStream;
import java.util.stream.StreamSupport;

import org.fuwjax.oss.util.RunWrapException;

public interface IntReader {
	static IntReader.Safe codepoints(final CharSequence chars) {
		return new StringIntReader(chars);
	}

	static IntReader.Safe codepoints(final IntStream codepoints) {
		final OfInt iter = codepoints.iterator();
		return () -> iter.hasNext() ? iter.nextInt() : -1;
	}

	static IntReader utf8ToCodepoint(final IntReader bytes) {
		return new Utf8IntReader(bytes);
	}

	static IntReader.Safe safeUtf8ToCodepoint(final IntReader.Safe bytes) {
		return safe(new Utf8IntReader(bytes));
	}

	static IntReader utf8ToCodepoint(final InputStream bytes) {
		return utf8ToCodepoint(bytes::read);
	}

	static IntReader.Safe utf8ToCodepoint(final ByteBuffer bytes) {
		return safeUtf8ToCodepoint(() -> bytes.hasRemaining() ? bytes.get() : -1);
	}

	static IntReader charToCodepoint(final IntReader chars) {
		return new Utf16IntReader(chars);
	}

	static IntReader.Safe safeCharToCodepoint(final IntReader.Safe chars) {
		return safe(new Utf16IntReader(chars));
	}

	static IntReader.Safe safe(final IntReader intReader) {
		return new IntReader.Safe() {
			@Override
			public int read() {
				try {
					return intReader.read();
				} catch(final IOException e) {
					throw new RunWrapException(e);
				}
			}
		};
	}

	static IntReader charToCodepoint(final Reader reader) {
		return charToCodepoint(reader::read);
	}

	static interface Safe extends IntReader {
		@Override
		int read();
	}

	/**
	 * Returns the next byte, char, or codepoint from the stream.
	 * @return the next codepoint or -1 if the stream has ended
	 * @throws IOException if there is an error reading from the underlying
	 *            stream
	 */
	int read() throws IOException;

	default IntStream stream() {
		return StreamSupport.intStream(new AbstractIntSpliterator(Long.MAX_VALUE, 0) {
			@Override
			public boolean tryAdvance(final IntConsumer action) {
				try {
					final int c = read();
					if(c != -1) {
						action.accept(c);
					}
					return c != -1;
				} catch(final IOException e) {
					throw new RunWrapException(e, "Failed reading from IntReader");
				}
			}

			@Override
			public boolean tryAdvance(final Consumer action) {
				try {
					final int c = read();
					if(c != -1) {
						action.accept(c);
					}
					return c != -1;
				} catch(final IOException e) {
					throw new RunWrapException(e, "Failed reading from IntReader");
				}
			}
		}, false);
	}
}