mirror of https://github.com/octoleo/plantuml.git
188 lines
6.9 KiB
Java
188 lines
6.9 KiB
Java
/*
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* Copyright 2003-2004, Franz-Josef Elmer, All rights reserved
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*
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* This library is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation; either version 2.1 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details
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* (http://www.gnu.org/copyleft/lesser.html).
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this library; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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package jcckit.util;
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/**
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* An implementation of <tt>ConfigData</tt> based on a flat
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* representation of the hierachically organized key-value pairs.
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* Concrete subclasses must implement the methods
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* {@link #getValue} and {@link #createConfigData} in accordance
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* with the Template Method pattern and Factory Method pattern,
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* respectively.
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* <p>
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* In a flat representation of hierachically organized key-value
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* pairs all key-value pairs are stored in a single <tt>Hashtable</tt>.
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* Its key is the <em>full key</em> of the configuration data (i.e. the key
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* including its path).
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* <p>
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* Example (using the notation for a <tt>.properties</tt> file):
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* <pre>
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* title = example
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* symbolAttributes/className = jcckit.graphic.BasicDrawingAttributes
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* symbolAttributes/fillColor = 0xcaffee
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* symbolAttributes/lineColor = 0xff0000
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* </pre>
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* The following table shows the result of some method calls at a
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* <tt>FlatConfigData</tt> instance prepared with
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* this example:
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* <p>
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* <center>
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* <table border=1 cellspacing=1 cellpadding=5>
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* <tr><th>Method call</th><th>Result</th></tr>
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* <tr><td>get("title")</td><td>example</td></tr>
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* <tr><td>getNode("symbolAttributes").get("fillColor")
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* </td><td>0xcaffee</td></tr>
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* </table>
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* </center>
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* <p>
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* In addition <tt>FlatConfigData</tt> implements <b>inheritance</b>
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* of key-value pairs.
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* Basically a node in the tree of key-value pairs
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* may extend another node in the tree.
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* The extended node inherit all key-value pairs from the extending
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* one including the key-value pairs of all descendants.
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* The value of a inherited key-value pair may be overridden.
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* Also new key-value pairs may be placed in the inherited node or
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* anywhere in the subtree.
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* Note, that the extending node has to be a node which is not a
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* descendant of the extended node (otherwise a circulary chain
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* of references occurs). As a consequence not more than 20 inheritance
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* levels are allowed.
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* <p>
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* The implementation of this kind of inheritance in a flat hashtable
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* is done by an additional key-value pair of the form
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* <pre>
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* <i>extending-node</i><b>/</b> = <i>extended-node</i><b>/</b>
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* </pre>
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* Example:
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* <pre>
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* A/a/priority = high
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* A/a/alpha/hello = universe
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* A/a/alpha/answer = 42
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* <b>A/b/1/ = A/a/</b>
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* A/b/1/alpha/hello = world
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* A/b/1/alpha/question = 6 * 7
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* </pre>
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* The following table shows the result of various method calls
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* applied at the node <tt>A/b/1/</tt> of a <tt>FlatConfigData</tt>
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* instance prepared with this example:
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* <p>
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* <center>
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* <table border=1 cellspacing=1 cellpadding=5>
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* <tr><th>Method call</th><th>Result</th><th>Comment</th></tr>
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* <tr><td>get("priority")</td><td>high</td><td>inherited</td></tr>
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* <tr><td>getNode("alpha").get("hello")
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* </td><td>world</td><td>overridden</td></tr>
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* <tr><td>getNode("alpha").get("question")
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* </td><td>6 * 7</td><td>added</td></tr>
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* <tr><td>getNode("alpha").get("answer")
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* </td><td>42</td><td>inherited</td></tr>
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* </table>
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* </center>
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*
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* @author Franz-Josef Elmer
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*/
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public abstract class FlatConfigData implements ConfigData {
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private final String _path;
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/** Creates a new instance for the specified path. */
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public FlatConfigData(String path) {
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_path = path;
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}
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/**
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* Returns the full key.
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* @param key A (relative) key. <tt>null</tt> is not allowed.
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* @return the path concatenated with <tt>key</tt> or <tt>key</tt>
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* if the path is undefined.
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*/
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public String getFullKey(String key) {
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return _path == null ? key : _path + key;
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}
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/**
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* Returns the value associated with this key.
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* @param key The relative key. <tt>null</tt> is not allowed.
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* @return the associated value. Will be <tt>null</tt> if no value exists
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* for <tt>key</tt>.
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*/
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public String get(String key) {
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return get(_path, key, 0);
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}
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/**
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* Obtains a value in accordance with hierarchy (<tt>path</tt>) and
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* inheritance (recursive calls of this routine).
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*/
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private String get(String path, String key, int numberOfLevels) {
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String result = null;
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if (numberOfLevels < 20) {
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String fullKey = path == null ? key : path + key;
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result = getValue(fullKey);
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if (result == null) {
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// posAfterDelim is the index in path just after '/'
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int posAfterDelim = path == null ? -1 : path.length();
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String replacement;
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while (posAfterDelim > 0) {
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// look for a sub-tree
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replacement = getValue(path.substring(0, posAfterDelim));
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if (replacement != null) {
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// sub-tree found, add last part of the original path
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result = get(replacement + path.substring(posAfterDelim), key,
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numberOfLevels + 1);
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// break whether result is null or not.
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break;
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}
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// remove last element from the path
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posAfterDelim = path.lastIndexOf('/', posAfterDelim - 2) + 1;
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}
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}
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}
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return result;
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}
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/**
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* Returns the <tt>ConfigData</tt> object associated with this key.
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* @param key The relative key.
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* @return the associated value. Will never return <tt>null</tt>.
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* Instead an empty <tt>ConfigData</tt> is returned.
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*/
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public ConfigData getNode(String key) {
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String path = (_path == null ? key : _path + key) + '/';
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return createConfigData(path);
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}
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/**
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* Returns the value for the specified full key from the flat
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* representation of the hierarchically organized key-value pairs.
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* @param fullKey The full key including path. <tt>null</tt> is not allowed.
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* @return the value or <tt>null</tt> if not found.
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*/
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protected abstract String getValue(String fullKey);
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/**
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* Returns the <tt>FlatConfigData</tt> object for the specified full path.
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* In general <tt>path</tt> will be used in the constructor with
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* path argument.
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* @param path The full path.
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* @return a new instance in any case.
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*/
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protected abstract ConfigData createConfigData(String path);
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}
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