GeometryIOUtils.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF 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.apache.commons.geometry.io.core.internal;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.Closeable;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.UncheckedIOException;
import java.net.URL;
import java.nio.charset.Charset;
import java.nio.file.Path;
import java.util.stream.Stream;

import org.apache.commons.geometry.io.core.input.GeometryInput;
import org.apache.commons.geometry.io.core.output.GeometryOutput;

/** Internal class containing utility methods for IO operations.
 */
public final class GeometryIOUtils {

    /** Path separator character used on Unix-like systems. */
    private static final char UNIX_PATH_SEP = '/';

    /** Path separator character used on Windows. */
    private static final char WINDOWS_PATH_SEP = '\\';

    /** Utility class; no instantiation. */
    private GeometryIOUtils() {}

    /** Get the file name of the given path or null if one does not exist
     * or is the empty string.
     * @param path path to get the file name of
     * @return file name of the given path
     */
    public static String getFileName(final Path path) {
        if (path != null) {
            return getFileName(path.toString());
        }

        return null;
    }

    /** Get the file name of the given url or null if one does not exist or is
     * the empty string.
     * @param url url to get the file name of
     * @return file name of the given url
     */
    public static String getFileName(final URL url) {
        if (url != null) {
            return getFileName(url.getPath());
        }

        return null;
    }

    /** Get the file name from the given path string, defined as
     * the substring following the last path separator character.
     * Null is returned if the argument is null or the file name is
     * the empty string.
     * @param path path to get the file name from
     * @return file name of the given path string or null if a
     *      non-empty file name does not exist
     */
    public static String getFileName(final String path) {
        if (path != null) {
            final int lastSep = Math.max(
                    path.lastIndexOf(UNIX_PATH_SEP),
                    path.lastIndexOf(WINDOWS_PATH_SEP));

            if (lastSep < path.length() - 1) {
                return path.substring(lastSep + 1);
            }
        }

        return null;
    }

    /** Get the part of the file name after the last dot.
     * @param fileName file name to get the extension for
     * @return the extension of the file name, the empty string if no extension is found, or
     *      null if the argument is null
     */
    public static String getFileExtension(final String fileName) {
        if (fileName != null) {
            final int idx = fileName.lastIndexOf('.');
            if (idx > -1) {
                return fileName.substring(idx + 1);
            }

            return "";
        }

        return null;
    }

    /** Create a {@link BufferedReader} for reading from the given input. The charset used is the charset
     * defined in {@code input} or {@code defaultCharset} if null.
     * @param input input to read from
     * @param defaultCharset charset to use if no charset is defined in the input
     * @return new reader instance
     * @throws UncheckedIOException if an I/O error occurs
     */
    public static BufferedReader createBufferedReader(final GeometryInput input, final Charset defaultCharset) {
        final Charset charset = input.getCharset() != null ?
                input.getCharset() :
                defaultCharset;

        return new BufferedReader(new InputStreamReader(input.getInputStream(), charset));
    }

    /** Create a {@link BufferedWriter} for writing to the given output. The charset used is the charset
     * defined in {@code output} or {@code defaultCharset} if null.
     * @param output output to write to
     * @param defaultCharset charset to use if no charset is defined in the output
     * @return new writer instance
     * @throws UncheckedIOException if an I/O error occurs
     */
    public static BufferedWriter createBufferedWriter(final GeometryOutput output, final Charset defaultCharset) {
        final Charset charset = output.getCharset() != null ?
                output.getCharset() :
                defaultCharset;

        return new BufferedWriter(new OutputStreamWriter(output.getOutputStream(), charset));
    }

    /** Get a value from {@code supplier}, wrapping any {@link IOException} with
     * {@link UncheckedIOException}.
     * @param <T> returned type
     * @param supplier object supplying the return value
     * @return supplied value
     * @throws UncheckedIOException if an I/O error occurs
     */
    public static <T> T getUnchecked(final IOSupplier<T> supplier) {
        try {
            return supplier.get();
        } catch (IOException exc) {
            throw createUnchecked(exc);
        }
    }

    /** Pass the given argument to the consumer, wrapping any {@link IOException} with
     * {@link UncheckedIOException}.
     * @param <T> argument type
     * @param consumer function to call
     * @param arg function argument
     * @throws UncheckedIOException if an I/O error occurs
     */
    public static <T> void acceptUnchecked(final IOConsumer<T> consumer, final T arg) {
        try {
            consumer.accept(arg);
        } catch (IOException exc) {
            throw createUnchecked(exc);
        }
    }

    /** Call the given function with the argument and return the {@code int} result, wrapping any
     * {@link IOException} with {@link UncheckedIOException}.
     * @param <T> argument type
     * @param fn function to call
     * @param arg function argument
     * @return int value
     * @throws UncheckedIOException if an I/O error occurs
     */
    public static <T> int applyAsIntUnchecked(final IOToIntFunction<T> fn, final T arg) {
        try {
            return fn.applyAsInt(arg);
        } catch (IOException exc) {
            throw createUnchecked(exc);
        }
    }

    /** Close the argument, wrapping any IO exceptions with {@link UncheckedIOException}.
     * @param closeable argument to close
     * @throws UncheckedIOException if an I/O error occurs
     */
    public static void closeUnchecked(final Closeable closeable) {
        try {
            closeable.close();
        } catch (IOException exc) {
            throw createUnchecked(exc);
        }
    }

    /** Create an unchecked exception from the given checked exception. The message of the
     * returned exception contains the original exception's type and message.
     * @param exc exception to wrap in an unchecked exception
     * @return the unchecked exception
     */
    public static UncheckedIOException createUnchecked(final IOException exc) {
        final String msg = exc.getClass().getSimpleName() + ": " + exc.getMessage();
        return new UncheckedIOException(msg, exc);
    }

    /** Create an exception indicating a parsing or syntax error.
     * @param msg exception message
     * @return an exception indicating a parsing or syntax error
     */
    public static IllegalStateException parseError(final String msg) {
        return parseError(msg, null);
    }

    /** Create an exception indicating a parsing or syntax error.
     * @param msg exception message
     * @param cause exception cause
     * @return an exception indicating a parsing or syntax error
     */
    public static IllegalStateException parseError(final String msg, final Throwable cause) {
        return new IllegalStateException(msg, cause);
    }

    /** Pass a supplied {@link Closeable} instance to {@code function} and return the result.
     * The {@code Closeable} instance returned by the supplier is closed if function execution
     * fails, otherwise the instance is <em>not</em> closed.
     * @param <T> Return type
     * @param <C> Closeable type
     * @param function function called with the supplied Closeable instance
     * @param closeableSupplier supplier used to obtain a Closeable instance
     * @return result of calling {@code function} with a supplied Closeable instance
     * @throws java.io.UncheckedIOException if an I/O error occurs
     */
    public static <T, C extends Closeable> T tryApplyCloseable(final IOFunction<C, T> function,
            final IOSupplier<? extends C> closeableSupplier) {
        C closeable = null;
        RuntimeException exc;
        try {
            closeable = closeableSupplier.get();
            return function.apply(closeable);
        } catch (RuntimeException e) {
            exc = e;
        } catch (IOException e) {
            exc = createUnchecked(e);
        }

        if (closeable != null) {
            try {
                closeable.close();
            } catch (IOException suppressed) {
                exc.addSuppressed(suppressed);
            }
        }

        throw exc;
    }

    /** Create a stream associated with an input stream. The input stream is closed when the
     * stream is closed and also closed if stream creation fails. Any {@link IOException} thrown
     * when the input stream is closed after the return of this method are wrapped with {@link UncheckedIOException}.
     * @param <T> Stream element type
     * @param <I> Input stream type
     * @param streamFunction function accepting an input stream and returning a stream
     * @param inputStreamSupplier supplier used to obtain the input stream
     * @return stream associated with the input stream return by the supplier
     * @throws java.io.UncheckedIOException if an I/O error occurs during input stream and stream creation
     */
    public static <T, I extends InputStream> Stream<T> createCloseableStream(
            final IOFunction<I, Stream<T>> streamFunction, final IOSupplier<? extends I> inputStreamSupplier) {
        return tryApplyCloseable(
                in -> streamFunction.apply(in).onClose(closeAsUncheckedRunnable(in)),
                inputStreamSupplier);
    }

    /** Return a {@link Runnable} that calls {@link Closeable#getClass() close()} on the argument,
     * wrapping any {@link IOException} with {@link UncheckedIOException}.
     * @param closeable instance to be closed
     * @return runnable that calls {@code close()) on the argument
     */
    private static Runnable closeAsUncheckedRunnable(final Closeable closeable) {
        return () -> closeUnchecked(closeable);
    }
}