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package com.sun.enterprise.admin.servermgmt.stringsubs.impl.algorithm;
/**
* Perform's string substitution for the given input. Substitution process look
* for the matching input in the given {@link RadixTree} and replaced the string
* with the corresponding matching value.
*
* @see {@link RadixTree}
*/
class RadixTreeSubstitution {
/** {@link RadixTree} used sub. */
private RadixTree _tree;
/** Buffer to store the current processing characters, reset when match found
* for the processed character. */
private StringBuffer _processedChars;
/** Reference to the currently processing node.*/
private RadixTreeNode _currentNode;
/** No of matched character in currently processing node. */
private int _nodeMatchedChars;
/** Last matched node value. */
private String _lastMatchedValue;
/** Buffer to store the characters need to re-process from root. */
private StringBuffer _reProcessChars;
/**
* Construct {@link RadixTreeSubstitution} for the given {@link RadixTree}.
* @param tree
*/
RadixTreeSubstitution(RadixTree tree) {
if (tree == null) {
throw new IllegalArgumentException("Invalid tree.");
}
_tree = tree;
_processedChars = new StringBuffer();
_currentNode = _tree.getRootNode();
}
/**
* Perform substitution by allowing continuous character feeding. Once
* the character sequence matched completely to {@link RadixTree} node
* and no further/extended match is available then the output is returned
* and the values reset to re-look the new input from root node.
* <p>
* Method maintains the processed characters, currently processing
* node and other parameters require in substitution.
* </p>
* <p>
* <b>NOTE:</b> A <code>null</code> input signify the end of the processing.
* </p>
* @param c Input character to match with the node key.
* @return
* <li>Value of the matching node, if no further match available.</li>
* <li>Return the string of processed characters if no matching node found
* or the node value is null.</li>
* <li><code>null</code> if waiting for more input char.</li>
*/
String substitute(Character c) {
StringBuffer outputBuffer = null;
boolean finalCall = (c == null) ? true : false;
do {
if (c != null) {
if (_reProcessChars != null && _reProcessChars.length() > 0) {
c = _reProcessChars.charAt(0);
_reProcessChars.delete(0, 1);
}
String nodeKey = _currentNode.getKey();
if (_nodeMatchedChars < nodeKey.length()) {
if (c == nodeKey.charAt(_nodeMatchedChars)) {
_processedChars.append(c);
_nodeMatchedChars++;
continue;
}
} else {
if (_currentNode.getValue() != null) {
_lastMatchedValue = _currentNode.getValue();
_processedChars.delete(0, _processedChars.length());
}
RadixTreeNode childNode = _currentNode.getChildNode(c);
if (childNode != null) {
_processedChars.append(c);
_currentNode = childNode;
_nodeMatchedChars = 1;
continue;
}
}
}
else if(_currentNode.getValue() != null &&
_nodeMatchedChars == _currentNode.getKey().length()) {
_lastMatchedValue = _currentNode.getValue();
_processedChars.delete(0, _processedChars.length());
}
if (outputBuffer == null) {
outputBuffer = new StringBuffer();
}
// write to the output buffer.
if (_lastMatchedValue != null) {
outputBuffer.append(_lastMatchedValue);
if (c != null) {
_processedChars.append(c);
}
_lastMatchedValue = null;
} else {
// If no match found than append the first character and start fresh from second character.
if (_processedChars.length() > 0) {
outputBuffer.append(_processedChars.charAt(0));
_processedChars.delete(0, 1);
if (c != null) {
_processedChars.append(c);
}
} else {
if (c != null) {
outputBuffer.append(c);
}
_processedChars.delete(0, _processedChars.length());
}
}
if (_processedChars.length() > 0) {
if (_reProcessChars == null) {
_reProcessChars = new StringBuffer(_processedChars);
} else {
_processedChars.append(_reProcessChars);
_reProcessChars.delete(0, _reProcessChars.length());
_reProcessChars.append(_processedChars);
}
c = _reProcessChars.charAt(0);
_processedChars.delete(0, _processedChars.length());
}
_currentNode = _tree.getRootNode();
_nodeMatchedChars = 0;
} while (_reProcessChars != null && _reProcessChars.length() > 0);
//Append the last process character sequence.
if (finalCall) {
if (_nodeMatchedChars == _currentNode.getKey().length()
&& _currentNode.getValue() != null) {
outputBuffer.append(_currentNode.getValue());
} else {
outputBuffer.append(_currentNode.getKey().substring(0, _nodeMatchedChars));
}
_processedChars.delete(0, _processedChars.length());
_currentNode = _tree.getRootNode();
_nodeMatchedChars = 0;
_lastMatchedValue = null;
}
return outputBuffer == null || outputBuffer.toString().isEmpty() ? null : outputBuffer.toString();
}
}