net.oneandone.sushi.fs.Filesystem Maven / Gradle / Ivy

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/*
 * Copyright 1&1 Internet AG, https://github.com/1and1/
 *
 * 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 net.oneandone.sushi.fs;

import net.oneandone.sushi.util.Separator;

import java.net.URI;
import java.util.Arrays;
import java.util.List;

/**
 * Filesystem classes built into sushi will fail with NoClassDefFound the optional maven dependencies are not available.
 */
public abstract class Filesystem {
    /**
     * Separator in URIs and paths. You'll rarely use this constant, in particular, it doesn't make sense to
     * use it in URI or path constants.
     */
	public static final char SEPARATOR_CHAR = '/';

    /**
     * Separator in URIs and paths. You'll rarely use this constant, in particular, it doesn't make sense to
     * use it in URI or path constants.
     */
	public static final String SEPARATOR_STRING = Character.toString(SEPARATOR_CHAR);

    public static final Separator SEPARATOR = Separator.on(SEPARATOR_CHAR);

    //--

    private final World world;
    private final Features features;
    private final String scheme;

    public Filesystem(World world, Features features, String scheme) {
        this.world = world;
        this.features = features;
        this.scheme = scheme;
    }

    public World getWorld() {
        return world;
    }

    public Features getFeatures() {
        return features;
    }

    public String getScheme() {
    	return scheme;
    }

    public abstract Node node(URI uri, Object extra) throws NodeInstantiationException;

    /** Helper Method for opaquePath implementations */
    public String after(String schemeSpecific, String separator) {
        int idx;

        idx = schemeSpecific.indexOf(separator);
        if (idx == -1) {
            return null;
        }
        return schemeSpecific.substring(idx + separator.length());
    }

    public void checkHierarchical(URI uri) throws NodeInstantiationException {
        if (uri.getFragment() != null) {
            throw new NodeInstantiationException(uri, "unexpected path fragment");
        }
        if (uri.getQuery() != null) {
            throw new NodeInstantiationException(uri, "unexpected query");
        }
        if (uri.isOpaque()) {
            throw new NodeInstantiationException(uri, "uri is not hierarchical");
        }
    }

    public void checkOpaque(URI uri) throws NodeInstantiationException {
        if (uri.getFragment() != null) {
            throw new NodeInstantiationException(uri, "unexpected path fragment");
        }
        if (uri.getQuery() != null) {
            throw new NodeInstantiationException(uri, "unexpected query");
        }
        if (!uri.isOpaque()) {
            throw new NodeInstantiationException(uri, "uri is not opaque");
        }
    }

    public String getCheckedPath(URI uri) throws NodeInstantiationException {
        String path;

        path = uri.getPath();
        if (path.length() > 0) {
            if (!path.startsWith(SEPARATOR_STRING)) {
                throw new NodeInstantiationException(uri, "missing initial separator " + SEPARATOR_STRING);
            }
            path = path.substring(1);
            if (path.endsWith(SEPARATOR_STRING)) {
                throw new NodeInstantiationException(uri, "invalid tailing " + SEPARATOR_STRING);
            }
        }
        return path;
    }

    //--

    public String join(String... names) {
        return join("", Arrays.asList(names));
    }

    public String join(String head, List paths) {
        StringBuilder builder;

        builder = new StringBuilder(head);
        for (String path : paths) {
            if (path.length() > 0) {
                if (path.startsWith(SEPARATOR_STRING)) {
                    throw new IllegalArgumentException(path);
                }
                if (builder.length() > 0) {
                    builder.append(SEPARATOR_STRING);
                }
                builder.append(path);
            }
        }
        normalize(builder);
        return builder.toString();
    }

    public void normalize(StringBuilder builder) {
        int idx;
        int prev;

        idx = 0;
        while (true) {
            idx = builder.indexOf(".", idx);
            if (idx == -1) {
                break;
            }
            if (idx + 1 < builder.length() && builder.charAt(idx + 1) == '.') {
                if (idx + 2 == builder.length() || builder.charAt(idx + 2) == SEPARATOR_CHAR) {
                    if (idx == 0) {
                        throw new IllegalArgumentException(builder.toString());
                    }
                    if (builder.charAt(idx - 1) == SEPARATOR_CHAR) {
                        prev = builder.lastIndexOf(SEPARATOR_STRING, idx - 2) + 1; // ok for -1
                        builder.delete(prev, idx + 1);
                        idx = prev;
                        if (builder.charAt(idx) == SEPARATOR_CHAR) {
                            builder.deleteCharAt(idx);
                        }
                        continue;
                    }
                }
            }
            if (idx == 0 || builder.charAt(idx - 1) == SEPARATOR_CHAR) {
                if (idx + 1 == builder.length() || builder.charAt(idx + 1) == SEPARATOR_CHAR) {
                    builder.deleteCharAt(idx);
                    if (idx < builder.length() && builder.charAt(idx) == SEPARATOR_CHAR) {
                        builder.deleteCharAt(idx);
                    } else if (idx > 0 && builder.charAt(idx - 1) == SEPARATOR_CHAR) {
                        builder.deleteCharAt(--idx);
                    }
                    continue;
                }
            }
            idx++;
        }
        // TODO: this is not part of java.net.URI's normalization
        for (int i = builder.length() - 1; i > 0; i--) {
            if (builder.charAt(i) == SEPARATOR_CHAR && builder.charAt(i - 1) == SEPARATOR_CHAR) {
                builder.deleteCharAt(i);
            }
        }
    }
}