001package org.jsoup.nodes;
002
003import org.jsoup.parser.ParseSettings;
004import org.jsoup.parser.Parser;
005import org.jspecify.annotations.Nullable;
006
007import java.io.IOException;
008
009/**
010 A comment node.
011
012 @author Jonathan Hedley, jonathan@hedley.net */
013public class Comment extends LeafNode {
014    /**
015     Create a new comment node.
016     @param data The contents of the comment
017     */
018    public Comment(String data) {
019        super(data);
020    }
021
022    @Override public String nodeName() {
023        return "#comment";
024    }
025
026    /**
027     Get the contents of the comment.
028     @return comment content
029     */
030    public String getData() {
031        return coreValue();
032    }
033
034    public Comment setData(String data) {
035        coreValue(data);
036        return this;
037    }
038
039    @Override
040        void outerHtmlHead(Appendable accum, int depth, Document.OutputSettings out) throws IOException {
041        if (out.prettyPrint() && ((isEffectivelyFirst() && parentNode instanceof Element && ((Element) parentNode).tag().formatAsBlock()) || (out.outline() )))
042            indent(accum, depth, out);
043        accum
044                .append("<!--")
045                .append(getData())
046                .append("-->");
047    }
048
049    @Override
050    void outerHtmlTail(Appendable accum, int depth, Document.OutputSettings out) {}
051
052    @Override
053    public Comment clone() {
054        return (Comment) super.clone();
055    }
056
057    /**
058     * Check if this comment looks like an XML Declaration. This is the case when the HTML parser sees an XML
059     * declaration or processing instruction. Other than doctypes, those aren't part of HTML, and will be parsed as a
060     * bogus comment.
061     * @return true if it looks like, maybe, it's an XML Declaration.
062     * @see #asXmlDeclaration()
063     */
064    public boolean isXmlDeclaration() {
065        String data = getData();
066        return isXmlDeclarationData(data);
067    }
068
069    private static boolean isXmlDeclarationData(String data) {
070        return (data.length() > 1 && (data.startsWith("!") || data.startsWith("?")));
071    }
072
073    /**
074     * Attempt to cast this comment to an XML Declaration node.
075     * @return an XML declaration if it could be parsed as one, null otherwise.
076     * @see #isXmlDeclaration()
077     */
078    public @Nullable XmlDeclaration asXmlDeclaration() {
079        String data = getData();
080
081        XmlDeclaration decl = null;
082        String declContent = data.substring(1, data.length() - 1);
083        // make sure this bogus comment is not immediately followed by another, treat as comment if so
084        if (isXmlDeclarationData(declContent))
085            return null;
086
087        String fragment = "<" + declContent + ">";
088        // use the HTML parser not XML, so we don't get into a recursive XML Declaration on contrived data
089        Document doc = Parser.htmlParser().settings(ParseSettings.preserveCase).parseInput(fragment, baseUri());
090        if (doc.body().childrenSize() > 0) {
091            Element el = doc.body().child(0);
092            decl = new XmlDeclaration(NodeUtils.parser(doc).settings().normalizeTag(el.tagName()), data.startsWith("!"));
093            decl.attributes().addAll(el.attributes());
094        }
095        return decl;
096    }
097}