Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You 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.apache.wicket.markup.parser; import java.io.BufferedInputStream; import java.io.IOException; import java.io.InputStream; import java.io.StringReader; import java.text.ParseException; import java.util.Locale; import org.apache.wicket.markup.parser.XmlTag.TagType; import org.apache.wicket.markup.parser.XmlTag.TextSegment; import org.apache.wicket.util.io.FullyBufferedReader; import org.apache.wicket.util.io.IOUtils; import org.apache.wicket.util.io.XmlReader; import org.apache.wicket.util.lang.Args; import org.apache.wicket.util.parse.metapattern.parsers.TagNameParser; import org.apache.wicket.util.parse.metapattern.parsers.VariableAssignmentParser; import org.apache.wicket.util.string.Strings; /** * A fairly shallow markup pull parser which parses a markup string of a given type of markup (for * example, html, xml, vxml or wml) into ComponentTag and RawMarkup tokens. * * @author Jonathan Locke * @author Juergen Donnerstag */ public final class XmlPullParser implements IXmlPullParser { /** */ public static final String STYLE = "style"; /** */ public static final String SCRIPT = "script"; /** * The encoding of the XML. */ private String encoding; /** * A XML independent reader which loads the whole source data into memory and which provides * convenience methods to access the data. */ private FullyBufferedReader input; /** temporary variable which will hold the name of the closing tag. */ private String skipUntilText; /** The last substring selected from the input */ private CharSequence lastText; /** Everything in between <!DOCTYPE ... > */ private CharSequence doctype; /** The type of what is in lastText */ private HttpTagType lastType = HttpTagType.NOT_INITIALIZED; /** The last tag found */ private XmlTag lastTag; /** * Construct. */ public XmlPullParser() { } @Override public final String getEncoding() { return encoding; } @Override public final CharSequence getDoctype() { return doctype; } @Override public final CharSequence getInputFromPositionMarker(final int toPos) { return input.getSubstring(toPos); } @Override public final CharSequence getInput(final int fromPos, final int toPos) { return input.getSubstring(fromPos, toPos); } /** * Whatever will be in between the current index and the closing tag, will be ignored (and thus * treated as raw markup (text). This is useful for tags like 'script'. * * @throws ParseException */ private void skipUntil() throws ParseException { // this is a tag with non-XHTML text as body - skip this until the // skipUntilText is found. final int startIndex = input.getPosition(); final int tagNameLen = skipUntilText.length(); int pos = input.getPosition() - 1; String endTagText = null; int lastPos = 0; while (!skipUntilText.equalsIgnoreCase(endTagText)) { pos = input.find("</", pos + 1); if ((pos == -1) || ((pos + (tagNameLen + 2)) >= input.size())) { throw new ParseException(skipUntilText + " tag not closed" + getLineAndColumnText(), startIndex); } lastPos = pos + 2; endTagText = input.getSubstring(lastPos, lastPos + tagNameLen).toString(); } input.setPosition(pos); lastText = input.getSubstring(startIndex, pos); lastType = HttpTagType.BODY; // Check that the tag is properly closed lastPos = input.find('>', lastPos + tagNameLen); if (lastPos == -1) { throw new ParseException(skipUntilText + " tag not closed" + getLineAndColumnText(), startIndex); } // Reset the state variable skipUntilText = null; } /** * * @return line and column number */ private String getLineAndColumnText() { return " (line " + input.getLineNumber() + ", column " + input.getColumnNumber() + ")"; } /** * @return XXX * @throws ParseException */ @Override public final HttpTagType next() throws ParseException { // Reached end of markup file? if (input.getPosition() >= input.size()) { return HttpTagType.NOT_INITIALIZED; } if (skipUntilText != null) { skipUntil(); return lastType; } // Any more tags in the markup? final int openBracketIndex = input.find('<'); // Tag or Body? if (input.charAt(input.getPosition()) != '<') { // It's a BODY if (openBracketIndex == -1) { // There is no next matching tag. lastText = input.getSubstring(-1); input.setPosition(input.size()); lastType = HttpTagType.BODY; return lastType; } lastText = input.getSubstring(openBracketIndex); input.setPosition(openBracketIndex); lastType = HttpTagType.BODY; return lastType; } // Determine the line number input.countLinesTo(openBracketIndex); // Get index of closing tag and advance past the tag int closeBracketIndex = -1; if (openBracketIndex != -1 && openBracketIndex < input.size() - 1) { char nextChar = input.charAt(openBracketIndex + 1); if ((nextChar == '!') || (nextChar == '?')) closeBracketIndex = input.find('>', openBracketIndex); else closeBracketIndex = input.findOutOfQuotes('>', openBracketIndex); } if (closeBracketIndex == -1) { throw new ParseException("No matching close bracket at" + getLineAndColumnText(), input.getPosition()); } // Get the complete tag text lastText = input.getSubstring(openBracketIndex, closeBracketIndex + 1); // Get the tagtext between open and close brackets String tagText = lastText.subSequence(1, lastText.length() - 1).toString(); if (tagText.length() == 0) { throw new ParseException("Found empty tag: '<>' at" + getLineAndColumnText(), input.getPosition()); } // Type of the tag, to be determined next final TagType type; // If the tag ends in '/', it's a "simple" tag like <foo/> if (tagText.endsWith("/")) { type = TagType.OPEN_CLOSE; tagText = tagText.substring(0, tagText.length() - 1); } else if (tagText.startsWith("/")) { // The tag text starts with a '/', it's a simple close tag type = TagType.CLOSE; tagText = tagText.substring(1); } else { // It must be an open tag type = TagType.OPEN; // If open tag and starts with "s" like "script" or "style", than ... if ((tagText.length() > STYLE.length()) && ((tagText.charAt(0) == 's') || (tagText.charAt(0) == 'S'))) { final String lowerCase = tagText.toLowerCase(Locale.ROOT); if (lowerCase.startsWith(SCRIPT)) { String typeAttr = "type="; int idxOfType = lowerCase.indexOf(typeAttr); if (idxOfType > 0) { // +1 to remove the ' or " String typePrefix = lowerCase.substring(idxOfType + typeAttr.length() + 1); if (typePrefix.startsWith("text/javascript")) { // prepare to skip everything between the open and close tag skipUntilText = SCRIPT; } // any other type is assumed to be a template so it can contain child nodes. // See WICKET-5288 } else { // no type attribute so it is 'text/javascript' // prepare to skip everything between the open and close tag skipUntilText = SCRIPT; } } else if (lowerCase.startsWith(STYLE)) { // prepare to skip everything between the open and close tag skipUntilText = STYLE; } } } // Handle special tags like <!-- and <![CDATA ... final char firstChar = tagText.charAt(0); if ((firstChar == '!') || (firstChar == '?')) { specialTagHandling(tagText, openBracketIndex, closeBracketIndex); input.countLinesTo(openBracketIndex); TextSegment text = new TextSegment(lastText, openBracketIndex, input.getLineNumber(), input.getColumnNumber()); lastTag = new XmlTag(text, type); return lastType; } TextSegment text = new TextSegment(lastText, openBracketIndex, input.getLineNumber(), input.getColumnNumber()); XmlTag tag = new XmlTag(text, type); lastTag = tag; // Parse the tag text and populate tag attributes if (parseTagText(tag, tagText)) { // Move to position after the tag input.setPosition(closeBracketIndex + 1); lastType = HttpTagType.TAG; return lastType; } else { throw new ParseException("Malformed tag" + getLineAndColumnText(), openBracketIndex); } } /** * Handle special tags like <!-- --> or <![CDATA[..]]> or <?xml> * * @param tagText * @param openBracketIndex * @param closeBracketIndex * @throws ParseException */ protected void specialTagHandling(String tagText, final int openBracketIndex, int closeBracketIndex) throws ParseException { // Handle comments if (tagText.startsWith("!--")) { // downlevel-revealed conditional comments e.g.: <!--[if (gt IE9)|!(IE)]><!--> if (tagText.contains("![endif]--")) { lastType = HttpTagType.CONDITIONAL_COMMENT_ENDIF; // Move to position after the tag input.setPosition(closeBracketIndex + 1); return; } // Conditional comment? E.g. // "<!--[if IE]><a href='test.html'>my link</a><![endif]-->" if (tagText.startsWith("!--[if ") && tagText.endsWith("]")) { int pos = input.find("]-->", openBracketIndex + 1); if (pos == -1) { throw new ParseException("Unclosed conditional comment beginning at" + getLineAndColumnText(), openBracketIndex); } pos += 4; lastText = input.getSubstring(openBracketIndex, pos); // Actually it is no longer a comment. It is now // up to the browser to select the section appropriate. input.setPosition(closeBracketIndex + 1); lastType = HttpTagType.CONDITIONAL_COMMENT; } else { // Normal comment section. // Skip ahead to "-->". Note that you can not simply test for // tagText.endsWith("--") as the comment might contain a '>' // inside. int pos = input.find("-->", openBracketIndex + 1); if (pos == -1) { throw new ParseException("Unclosed comment beginning at" + getLineAndColumnText(), openBracketIndex); } pos += 3; lastText = input.getSubstring(openBracketIndex, pos); lastType = HttpTagType.COMMENT; input.setPosition(pos); } return; } // The closing tag of a conditional comment, e.g. // "<!--[if IE]><a href='test.html'>my link</a><![endif]--> // and also <!--<![endif]-->" if (tagText.equals("![endif]--")) { lastType = HttpTagType.CONDITIONAL_COMMENT_ENDIF; input.setPosition(closeBracketIndex + 1); return; } // CDATA sections might contain "<" which is not part of an XML tag. // Make sure escaped "<" are treated right if (tagText.startsWith("![")) { final String startText = (tagText.length() <= 8 ? tagText : tagText.substring(0, 8)); if (startText.toUpperCase(Locale.ROOT).equals("![CDATA[")) { int pos1 = openBracketIndex; do { // Get index of closing tag and advance past the tag closeBracketIndex = findChar('>', pos1); if (closeBracketIndex == -1) { throw new ParseException("No matching close bracket at" + getLineAndColumnText(), input.getPosition()); } // Get the tagtext between open and close brackets tagText = input.getSubstring(openBracketIndex + 1, closeBracketIndex).toString(); pos1 = closeBracketIndex + 1; } while (tagText.endsWith("]]") == false); // Move to position after the tag input.setPosition(closeBracketIndex + 1); lastText = tagText; lastType = HttpTagType.CDATA; return; } } if (tagText.charAt(0) == '?') { lastType = HttpTagType.PROCESSING_INSTRUCTION; // Move to position after the tag input.setPosition(closeBracketIndex + 1); return; } if (tagText.startsWith("!DOCTYPE")) { lastType = HttpTagType.DOCTYPE; // Get the tagtext between open and close brackets doctype = input.getSubstring(openBracketIndex + 1, closeBracketIndex); // Move to position after the tag input.setPosition(closeBracketIndex + 1); return; } // Move to position after the tag lastType = HttpTagType.SPECIAL_TAG; input.setPosition(closeBracketIndex + 1); } /** * @return MarkupElement */ @Override public final XmlTag getElement() { return lastTag; } /** * @return The xml string from the last element */ @Override public final CharSequence getString() { return lastText; } /** * @return The next XML tag * @throws ParseException */ public final XmlTag nextTag() throws ParseException { while (next() != HttpTagType.NOT_INITIALIZED) { switch (lastType) { case TAG: return lastTag; case BODY: break; case COMMENT: break; case CONDITIONAL_COMMENT: break; case CDATA: break; case PROCESSING_INSTRUCTION: break; case SPECIAL_TAG: break; } } return null; } /** * Find the char but ignore any text within ".." and '..' * * @param ch * The character to search * @param startIndex * Start index * @return -1 if not found, else the index */ private int findChar(final char ch, int startIndex) { char quote = 0; for (; startIndex < input.size(); startIndex++) { final char charAt = input.charAt(startIndex); if (quote != 0) { if (quote == charAt) { quote = 0; } } else if ((charAt == '"') || (charAt == '\'')) { quote = charAt; } else if (charAt == ch) { return startIndex; } } return -1; } /** * Parse the given string. * <p> * Note: xml character encoding is NOT applied. It is assumed the input provided does have the * correct encoding already. * * @param string * The input string * @throws IOException * Error while reading the resource */ @Override public void parse(final CharSequence string) throws IOException { Args.notNull(string, "string"); this.input = new FullyBufferedReader(new StringReader(string.toString())); this.encoding = null; } /** * Reads and parses markup from an input stream, using UTF-8 encoding by default when not * specified in XML declaration. * * @param in * The input stream to read and parse * @throws IOException * * @see {@link #parse(InputStream, String)} */ @Override public void parse(final InputStream in) throws IOException { // When XML declaration does not specify encoding, it defaults to UTF-8 parse(in, "UTF-8"); } /** * Reads and parses markup from an input stream. * <p> * Note: The input is closed after parsing. * * @param inputStream * The input stream to read and parse * @param encoding * The default character encoding of the input * @throws IOException */ @Override public void parse(final InputStream inputStream, final String encoding) throws IOException { Args.notNull(inputStream, "inputStream"); try { XmlReader xmlReader = new XmlReader(new BufferedInputStream(inputStream, 4000), encoding); this.input = new FullyBufferedReader(xmlReader); this.encoding = xmlReader.getEncoding(); } finally { IOUtils.closeQuietly(inputStream); } } @Override public final void setPositionMarker() { input.setPositionMarker(input.getPosition()); } @Override public final void setPositionMarker(final int pos) { input.setPositionMarker(pos); } @Override public String toString() { return input.toString(); } /** * Parses the text between tags. For example, "a href=foo.html". * * @param tag * @param tagText * The text between tags * @return false in case of an error * @throws ParseException */ private boolean parseTagText(final XmlTag tag, final String tagText) throws ParseException { // Get the length of the tagtext final int tagTextLength = tagText.length(); // If we match tagname pattern final TagNameParser tagnameParser = new TagNameParser(tagText); if (tagnameParser.matcher().lookingAt()) { // Extract the tag from the pattern matcher tag.name = tagnameParser.getName(); tag.namespace = tagnameParser.getNamespace(); // Are we at the end? Then there are no attributes, so we just // return the tag int pos = tagnameParser.matcher().end(0); if (pos == tagTextLength) { return true; } // Extract attributes final VariableAssignmentParser attributeParser = new VariableAssignmentParser(tagText); while (attributeParser.matcher().find(pos)) { // Get key and value using attribute pattern String value = attributeParser.getValue(); // In case like <html xmlns:wicket> will the value be null if (value == null) { value = ""; } // Set new position to end of attribute pos = attributeParser.matcher().end(0); // Chop off double quotes or single quotes if (value.startsWith("\"") || value.startsWith("\'")) { value = value.substring(1, value.length() - 1); } // Trim trailing whitespace value = value.trim(); // Unescape value = Strings.unescapeMarkup(value).toString(); // Get key final String key = attributeParser.getKey(); // Put the attribute in the attributes hash if (null != tag.getAttributes().put(key, value)) { throw new ParseException("Same attribute found twice: " + key + getLineAndColumnText(), input.getPosition()); } // The input has to match exactly (no left over junk after // attributes) if (pos == tagTextLength) { return true; } } return true; } return false; } }