org.pageseeder.diffx.xml.Sequences Maven / Gradle / Ivy
/*
* Copyright 2010-2021 Allette Systems (Australia)
* http://www.allette.com.au
*
* 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 org.pageseeder.diffx.xml;
import org.pageseeder.diffx.token.*;
import org.pageseeder.diffx.token.impl.TextListToken;
import java.util.ArrayList;
import java.util.List;
import java.util.Stack;
/**
* A utility class for token sequences.
*
* @author Christophe Lauret
* @version 0.9.0
* @since 0.6
*/
public final class Sequences {
/**
* Prevent creation of instances.
*/
private Sequences() {
}
/**
* 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(Sequence sequence) {
if (sequence == null) return false;
Stack open = new Stack<>();
XMLToken token;
for (int i = 0; i < sequence.size(); i++) {
token = sequence.getToken(i);
if (token.getType() == XMLTokenType.START_ELEMENT) {
open.push(token);
} else if (token.getType() == XMLTokenType.END_ELEMENT) {
if (open.empty()) return false;
StartElementToken o = (StartElementToken) open.peek();
String lastOpenElementName = o.getName();
String closeElementName = token.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 tokens.
*
* @param sequence The sequence
*
* @return The maximum depth.
*/
public static int getMaxDepth(Sequence sequence) {
int max = 0;
int depth = 0;
for (int i = 0; i < sequence.size(); i++) {
if (sequence.getToken(i) instanceof StartElementToken) {
depth++;
} else if (sequence.getToken(i) instanceof EndElementToken) {
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(Sequence sequence) {
int max = 0;
int tmp = 0;
for (int i = 0; i < sequence.size(); i++) {
XMLToken token = sequence.getToken(i);
if (token instanceof StartElementToken) {
tmp = 0;
} else if (token instanceof EndElementToken) {
if (tmp > max) {
max = tmp;
}
} else {
tmp++;
}
}
return max;
}
/**
* Fold consecutive text tokens into a single token while preserving the original tokens.
*
* @param input The input sequence
*
* @return The collapsed sequence.
*/
public static Sequence foldText(Sequence input) {
List text = new ArrayList<>();
Sequence output = new Sequence(input.getNamespaces());
for (XMLToken token : input) {
if (token instanceof TextToken) {
text.add((TextToken) token);
} else {
if (text.size() > 1) {
output.addToken(new TextListToken(text));
text.clear();
} else if (text.size() == 1) {
output.addToken(text.remove(0));
}
output.addToken(token);
}
}
return output;
}
}