com.topologi.diffx.sequence.EventSequenceUtils Maven / Gradle / Ivy
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package com.topologi.diffx.sequence;
import java.util.Stack;
import com.topologi.diffx.event.DiffXEvent;
import com.topologi.diffx.event.OpenElementEvent;
import com.topologi.diffx.event.CloseElementEvent;
/**
* A utility class for event sequences.
*
* @author Christophe Lauret
* @version 3 April 2005
*/
public final class EventSequenceUtils {
/**
* Prevent creation of instances.
*/
private EventSequenceUtils() {
}
/**
* Indicates whether the sequence corresponds to well-formed XML.
*
* @param sequence The sequence.
*
* @return true
if the sequence is "well-formed";
* false
otherwise.
*/
public static boolean isWellFormed(EventSequence sequence) {
// TODO: if the sequence is null ??
if (sequence == null) return false;
Stack open = new Stack();
DiffXEvent e = null;
for (int i = 0; i < sequence.size(); i++) {
e = sequence.getEvent(i);
if (e instanceof OpenElementEvent) {
open.push(e);
} else if (e instanceof CloseElementEvent) {
if (open.empty()) return false;
OpenElementEvent o = (OpenElementEvent)open.peek();
String lastOpenElementName = o.getName();
String closeElementName = ((CloseElementEvent)e).getName();
if (!closeElementName.equals(lastOpenElementName)) return false;
}
}
return open.empty();
}
/**
* Returns the maximum depth of the sequence.
*
* This method assumes that the sequence is well-formed, and counts
* the maximum number of open element events.
*
* @param sequence The sequence
*
* @return The maximum depth.
*/
public static int getMaxDepth(EventSequence sequence) {
int max = 0;
int depth = 0;
for (int i = 0; i < sequence.size(); i++) {
if (sequence.getEvent(i) instanceof OpenElementEvent)
depth++;
else if (sequence.getEvent(i) instanceof CloseElementEvent)
depth--;
if (depth > max) max = depth;
}
return max;
}
/**
* Returns the maximum number of token inside an element tag.
*
*
This method assumes that the sequence is well-formed.
*
* @param sequence The sequence.
*
* @return The maximum number of tokens.
*/
public static int getMaxElementContent(EventSequence sequence) {
int max = 0;
int tmp = 0;
for (int i = 0; i < sequence.size(); i++) {
DiffXEvent e = sequence.getEvent(i);
if (e instanceof OpenElementEvent) {
tmp = 0;
} else if (e instanceof CloseElementEvent) {
if (tmp > max) max = tmp;
} else tmp++;
}
return max;
}
}