gr.xe.conf.ConfReader.java Source code

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Here is the source code for gr.xe.conf.ConfReader.java

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/*
 * Copyright 2011 Kapelonis Kostis
 *
 * 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 gr.xe.conf;

import gr.xe.conf.lines.CommentLine;
import gr.xe.conf.lines.LineReader;
import gr.xe.conf.lines.PathLine;
import gr.xe.conf.lines.ValueLine;
import gr.xe.conf.tree.ConfNode;
import gr.xe.conf.tree.PathNode;

import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import org.apache.commons.io.IOUtils;
import org.apache.commons.lang.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * @author kkapelonis
 */
public class ConfReader {
    private static final Logger logger = LoggerFactory.getLogger(ConfReader.class);

    private ConfNode rootNode = null;
    private List<LineReader> readers = null;

    /**
     * Creates a new instance of ConfReader
     */
    public ConfReader() {
        rootNode = new PathNode(null);
        readers = new ArrayList<LineReader>();
        readers.add(new CommentLine());
        readers.add(new PathLine());
        readers.add(new ValueLine());
    }

    /**
     * Reads a legacy .conf Perl file
     * @param in the file
     * @throws IOException something was wrong during reading.
     */
    public void readFile(InputStream in) throws IOException {
        List<String> lines = IOUtils.readLines(in);

        for (String line : lines) {
            if (StringUtils.isBlank(line)) {
                continue;
            }
            boolean ok = process(line);
            if (!ok) {
                logger.warn("Unknown line {}", line);
            }
        }

    }

    private boolean process(String line) {
        for (LineReader reader : readers) {
            if (reader.matches(line)) {
                rootNode = reader.process(rootNode, line);
                return true;
            }
        }
        return false;
    }

    /**
     * Finds a value in the configuration file
     * @param path a path using full stops
     * @return the value or null if nothing was found
     */
    public String readValue(String path) {
        ConfNode node = followPath(path);
        if (node != null) {
            return node.getValue();
        } else {
            return null;
        }
    }

    /**
     * Finds all available keys that hang from this path
     * 
     * @param path a path using full stops
     * @return the values found
     */
    public Set<String> readKeys(String path) {
        ConfNode node = followPath(path);
        if (node != null) {
            return node.getChildren().keySet();
        } else {
            return new HashSet<String>();
        }
    }

    /**
     * Checks if a key is present or not
     * 
     * @param path a path using full stops
     * @return true if the key exists
     */
    public boolean keyExists(String path) {
        return followPath(path) != null;
    }

    private ConfNode followPath(String path) {
        String[] paths = path.split("\\.");
        ConfNode start = rootNode;
        for (String pathName : paths) {
            if (!start.getChildren().containsKey(pathName)) {
                return null;
            }
            start = start.getChildren().get(pathName);
        }
        return start;
    }

}