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+/* tagStack.java -- The HTML tag stack.
+ Copyright (C) 2005 Free Software Foundation, Inc.
+
+This file is part of GNU Classpath.
+
+GNU Classpath is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+GNU Classpath is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Classpath; see the file COPYING. If not, write to the
+Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301 USA.
+
+Linking this library statically or dynamically with other modules is
+making a combined work based on this library. Thus, the terms and
+conditions of the GNU General Public License cover the whole
+combination.
+
+As a special exception, the copyright holders of this library give you
+permission to link this library with independent modules to produce an
+executable, regardless of the license terms of these independent
+modules, and to copy and distribute the resulting executable under
+terms of your choice, provided that you also meet, for each linked
+independent module, the terms and conditions of the license of that
+module. An independent module is a module which is not derived from
+or based on this library. If you modify this library, you may extend
+this exception to your version of the library, but you are not
+obligated to do so. If you do not wish to do so, delete this
+exception statement from your version. */
+
+
+package gnu.javax.swing.text.html.parser;
+
+import gnu.java.lang.CPStringBuilder;
+
+import gnu.javax.swing.text.html.parser.models.node;
+import gnu.javax.swing.text.html.parser.models.transformer;
+
+import java.util.BitSet;
+import java.util.Enumeration;
+import java.util.LinkedList;
+import java.util.ListIterator;
+
+import javax.swing.text.SimpleAttributeSet;
+import javax.swing.text.html.HTML;
+import javax.swing.text.html.parser.*;
+
+/**
+ * <p>The HTML content validator, is responsible for opening and
+ * closing elements with optional start/end tags, detecting
+ * the wrongly placed html tags and reporting errors. The working instance
+ * is the inner class inside the {@link javax.swing.text.html.parser.Parser }
+ * </p>
+ * <p>This class could potentially
+ * provide basis for automated closing and insertion of the html tags,
+ * correcting the found html errors.
+ * @author Audrius Meskauskas, Lithuania (AudriusA@Bioinformatics.org)
+ */
+public abstract class htmlValidator
+{
+ /**
+ * The tag reference, holding additional information that the tag
+ * has been forcibly closed.
+ */
+ protected class hTag
+ {
+ protected final Element element;
+ protected final HTML.Tag tag;
+ protected final TagElement tgElement;
+ protected boolean forcibly_closed;
+ protected node validationTrace;
+
+ protected hTag(TagElement an_element)
+ {
+ element = an_element.getElement();
+ tag = an_element.getHTMLTag();
+ tgElement = an_element;
+
+ if (element.content != null)
+ validationTrace = transformer.transform(element.content, dtd);
+ }
+
+ /**
+ * This is called when the tag must be forcibly closed because
+ * it would make the newly appearing tag invalid.
+ * The parser is not notified about such event (just the error
+ * is reported). For such tags, the closing message does not
+ * appear when later reaching the end of stream. The exception is
+ * the &lt;head&gt; tag: the parser is notified about its silent closing
+ * when &lt;body&gt; or other html content appears.
+ */
+ protected void forciblyCloseDueContext()
+ {
+ forcibly_closed = true;
+ }
+
+ /**
+ * This is called when the tag must be forcibly closed after
+ * reaching the end of stream. The parser is notified as if
+ * closing the tag explicitly.
+ */
+ protected void forciblyCloseDueEndOfStream()
+ {
+ forcibly_closed = true;
+ handleSupposedEndTag(element);
+ }
+ }
+
+ /**
+ * The DTD, providing information about the valid document structure.
+ */
+ protected final DTD dtd;
+
+ /**
+ * The stack, holding the current tag context.
+ */
+ protected final LinkedList stack = new LinkedList();
+
+ /**
+ * Creates a new tag stack, using the given DTD.
+ * @param a_dtd A DTD, providing the information about the valid
+ * tag content.
+ */
+ public htmlValidator(DTD a_dtd)
+ {
+ dtd = a_dtd;
+ }
+
+ /**
+ * Close all opened tags (called at the end of parsing).
+ */
+ public void closeAll()
+ {
+ hTag h;
+ while (!stack.isEmpty())
+ {
+ h = (hTag) stack.getLast();
+ if (!h.forcibly_closed && !h.element.omitEnd())
+ s_error("Unclosed <" + h.tag + ">, closing at the end of stream");
+
+ handleSupposedEndTag(h.element);
+
+ closeTag(h.tgElement);
+ }
+ }
+
+ /**
+ * Remove the given tag from the stack or (if found) from the list
+ * of the forcibly closed tags.
+ */
+ public boolean closeTag(TagElement tElement)
+ {
+ HTML.Tag tag = tElement.getHTMLTag();
+ hTag x;
+ hTag close;
+
+ if (!stack.isEmpty())
+ {
+ ListIterator iter = stack.listIterator(stack.size());
+
+ while (iter.hasPrevious())
+ {
+ x = (hTag) iter.previous();
+ if (tag.equals(x.tag))
+ {
+ if (x.forcibly_closed && !x.element.omitEnd())
+ s_error("The tag <" + x.tag +
+ "> has already been forcibly closed"
+ );
+
+
+ // If the tag has a content model defined, forcibly close all
+ // tags that were opened after the tag being currently closed.
+ closing:
+ if (x.element.content != null)
+ {
+ iter = stack.listIterator(stack.size());
+ while (iter.hasPrevious())
+ {
+ close = (hTag) iter.previous();
+ if (close == x)
+ break closing;
+ handleSupposedEndTag(close.element);
+ iter.remove();
+ }
+ }
+
+ stack.remove(x);
+ return true;
+ }
+ }
+ }
+ s_error("Closing unopened <" + tag + ">");
+ return false;
+ }
+
+ /**
+ * Add the given HTML tag to the stack of the opened tags. Forcibly closes
+ * all tags in the stack that does not allow this tag in they content (error
+ * is reported).
+ * @param element
+ */
+ public void openTag(TagElement tElement, htmlAttributeSet parameters)
+ {
+ // If this is a fictional call, the message from the parser
+ // has recursively returned - ignore.
+ if (tElement.fictional())
+ return;
+
+ validateParameters(tElement, parameters);
+
+ // If the stack is empty, start from HTML
+ if (stack.isEmpty() && tElement.getHTMLTag() != HTML.Tag.HTML)
+ {
+ Element html = dtd.getElement(HTML.Tag.HTML.toString());
+ openFictionalTag(html);
+ }
+
+ Object v = tagIsValidForContext(tElement);
+ if (v != Boolean.TRUE)
+ {
+ // The tag is not valid for context, the content
+ // model suggest to open another tag.
+ if (v instanceof Element)
+ {
+ int n = 0;
+ while (v instanceof Element && (n++ < 100))
+ {
+ Element fe = (Element) v;
+
+ // notify the content model that we add the proposed tag
+ node ccm = getCurrentContentModel();
+ if (ccm != null)
+ ccm.show(fe);
+ openFictionalTag(fe);
+
+ Object vv = tagIsValidForContext(tElement);
+ if (vv instanceof Element) // One level of nesting is supported.
+ {
+ openFictionalTag((Element) vv);
+
+ Object vx = tagIsValidForContext(tElement);
+ if (vx instanceof Element)
+ openFictionalTag((Element) vx);
+ }
+ else if (vv == Boolean.FALSE)
+ {
+ // The tag is still not valid for the current
+ // content after opening a fictional element.
+ if (fe.omitEnd())
+ {
+ // close the previously opened fictional tag.
+ closeLast();
+ vv = tagIsValidForContext(tElement);
+ if (vv instanceof Element)
+
+ // another tag was suggested by the content model
+ openFictionalTag((Element) vv);
+ }
+ }
+ v = tagIsValidForContext(tElement);
+ }
+ }
+ else // If the current element has the optional end tag, close it.
+ {
+ if (!stack.isEmpty())
+ {
+ closing:
+ do
+ {
+ hTag last = (hTag) stack.getLast();
+ if (last.element.omitEnd())
+ {
+ closeLast();
+ v = tagIsValidForContext(tElement);
+ if (v instanceof Element) // another tag was suggested by the content model
+ {
+ openFictionalTag((Element) v);
+ break closing;
+ }
+ }
+ else
+ break closing;
+ }
+ while (v == Boolean.FALSE && !stack.isEmpty());
+ }
+ }
+ }
+
+ stack.add(new hTag(tElement));
+ }
+
+ /**
+ * Clear the stack.
+ */
+ public void restart()
+ {
+ stack.clear();
+ }
+
+ /**
+ * Check if this tag is valid for the current context. Return Boolean.True if
+ * it is OK, Boolean.False if it is surely not OK or the Element that the
+ * content model recommends to insert making the situation ok. If Boolean.True
+ * is returned, the content model current position is moved forward. Otherwise
+ * this position remains the same.
+ *
+ * @param tElement
+ * @return
+ */
+ public Object tagIsValidForContext(TagElement tElement)
+ {
+ // Check the current content model, if one is available.
+ node cv = getCurrentContentModel();
+
+ if (cv != null)
+ return cv.show(tElement.getElement());
+
+ // Check exclusions and inclusions.
+ ListIterator iter = stack.listIterator(stack.size());
+ hTag t = null;
+ final int idx = tElement.getElement().index;
+
+ // Check only known tags.
+ if (idx >= 0)
+ {
+ BitSet inclusions = new BitSet();
+ while (iter.hasPrevious())
+ {
+ t = (hTag) iter.previous();
+ if (! t.forcibly_closed)
+ {
+ if (t.element.exclusions != null
+ && t.element.exclusions.get(idx))
+ return Boolean.FALSE;
+
+ if (t.element.inclusions != null)
+ inclusions.or(t.element.inclusions);
+ }
+ }
+ if (! inclusions.get(idx))
+ {
+ // If we need to insert something, and cannot do this, but
+ // it is allowed to insert the paragraph here, insert the
+ // paragraph.
+ Element P = dtd.getElement(HTML_401F.P);
+ if (inclusions.get(P.index))
+ return P;
+ else
+ return Boolean.FALSE;
+ }
+ }
+ return Boolean.TRUE;
+ }
+
+ /**
+ * Validate tag without storing in into the tag stack. This is called
+ * for the empty tags and results the subsequent calls to the openTag
+ * and closeTag.
+ */
+ public void validateTag(TagElement tElement, htmlAttributeSet parameters)
+ {
+ openTag(tElement, parameters);
+ closeTag(tElement);
+ }
+
+ /**
+ * Check for mandatory elements, subsequent to the last tag:
+ * @param tElement The element that will be inserted next.
+ */
+ protected void checkContentModel(TagElement tElement, boolean first)
+ {
+ if (stack.isEmpty())
+ return;
+
+ hTag last = (hTag) stack.getLast();
+ if (last.validationTrace == null)
+ return;
+
+ Object r = last.validationTrace.show(tElement.getElement());
+ if (r == Boolean.FALSE)
+ s_error("The <" + last.element + "> does not match the content model " +
+ last.validationTrace
+ );
+ else if (r instanceof Element) // The content model recommends insertion of this element
+ {
+ if (!first)
+ closeTag(last.tgElement);
+ handleSupposedStartTag((Element) r);
+ openTag(new TagElement((Element) r), null);
+ }
+ }
+
+ /**
+ * The method is called when the tag must be closed because
+ * it does not allow the subsequent elements inside its context
+ * or the end of stream has been reached. The parser is only
+ * informed if the element being closed does not require the
+ * end tag (the "omitEnd" flag is set).
+ * The closing message must be passed to the parser mechanism
+ * before passing message about the opening the next tag.
+ *
+ * @param element The tag being fictionally (forcibly) closed.
+ */
+ protected abstract void handleSupposedEndTag(Element element);
+
+ /**
+ * The method is called when the validator decides to open the
+ * tag on its own initiative. This may happen if the content model
+ * includes the element with the optional (supposed) start tag.
+ *
+ * @param element The tag being opened.
+ */
+ protected abstract void handleSupposedStartTag(Element element);
+
+ /**
+ * Handles the error message. This method must be overridden to pass
+ * the message where required.
+ * @param msg The message text.
+ */
+ protected abstract void s_error(String msg);
+
+ /**
+ * Validate the parameters, report the error if the given parameter is
+ * not in the parameter set, valid for the given attribute. The information
+ * about the valid parameter set is taken from the Element, enclosed
+ * inside the tag. The method does not validate the default parameters.
+ * @param tag The tag
+ * @param parameters The parameters of this tag.
+ */
+ protected void validateParameters(TagElement tag, htmlAttributeSet parameters)
+ {
+ if (parameters == null ||
+ parameters == htmlAttributeSet.EMPTY_HTML_ATTRIBUTE_SET ||
+ parameters == SimpleAttributeSet.EMPTY
+ )
+ return;
+
+ Enumeration enumeration = parameters.getAttributeNames();
+
+ while (enumeration.hasMoreElements())
+ {
+ validateAttribute(tag, parameters, enumeration);
+ }
+
+ // Check for missing required values.
+ AttributeList a = tag.getElement().getAttributes();
+
+ while (a != null)
+ {
+ if (a.getModifier() == DTDConstants.REQUIRED)
+ if (parameters.getAttribute(a.getName()) == null)
+ {
+ s_error("Missing required attribute '" + a.getName() + "' for <" +
+ tag.getHTMLTag() + ">"
+ );
+ }
+ a = a.next;
+ }
+ }
+
+ private node getCurrentContentModel()
+ {
+ if (!stack.isEmpty())
+ {
+ hTag last = (hTag) stack.getLast();
+ return last.validationTrace;
+ }
+ else
+ return null;
+ }
+
+ private void closeLast()
+ {
+ handleSupposedEndTag(((hTag) stack.getLast()).element);
+ stack.removeLast();
+ }
+
+ private void openFictionalTag(Element e)
+ {
+ handleSupposedStartTag(e);
+ stack.add(new hTag(new TagElement(e, true)));
+ if (!e.omitStart())
+ s_error("<" + e + "> is expected (supposing it)");
+ }
+
+ private void validateAttribute(TagElement tag, htmlAttributeSet parameters,
+ Enumeration enumeration
+ )
+ {
+ Object foundAttribute;
+ AttributeList dtdAttribute;
+ foundAttribute = enumeration.nextElement();
+ dtdAttribute = tag.getElement().getAttribute(foundAttribute.toString());
+ if (dtdAttribute == null)
+ {
+ CPStringBuilder valid =
+ new CPStringBuilder("The tag <" + tag.getHTMLTag() +
+ "> cannot contain the attribute '" + foundAttribute +
+ "'. The valid attributes for this tag are: "
+ );
+
+ AttributeList a = tag.getElement().getAttributes();
+
+ while (a != null)
+ {
+ valid.append(a.name.toUpperCase());
+ valid.append(' ');
+ a = a.next;
+ }
+ s_error(valid.toString());
+ }
+
+ else
+ {
+ String value = parameters.getAttribute(foundAttribute).toString();
+
+ if (dtdAttribute.type == DTDConstants.NUMBER)
+ validateNumberAttribute(tag, foundAttribute, value);
+
+ if (dtdAttribute.type == DTDConstants.NAME ||
+ dtdAttribute.type == DTDConstants.ID
+ )
+ validateNameOrIdAttribute(tag, foundAttribute, value);
+
+ if (dtdAttribute.values != null)
+ validateAttributeWithValueList(tag, foundAttribute, dtdAttribute,
+ value
+ );
+ }
+ }
+
+ private void validateAttributeWithValueList(TagElement tag,
+ Object foundAttribute,
+ AttributeList dtdAttribute,
+ String value
+ )
+ {
+ if (!dtdAttribute.values.contains(value.toLowerCase()) &&
+ !dtdAttribute.values.contains(value.toUpperCase())
+ )
+ {
+ CPStringBuilder valid;
+ if (dtdAttribute.values.size() == 1)
+ valid =
+ new CPStringBuilder("The attribute '" + foundAttribute +
+ "' of the tag <" + tag.getHTMLTag() +
+ "> cannot have the value '" + value +
+ "'. The only valid value is "
+ );
+ else
+ valid =
+ new CPStringBuilder("The attribute '" + foundAttribute +
+ "' of the tag <" + tag.getHTMLTag() +
+ "> cannot have the value '" + value + "'. The " +
+ dtdAttribute.values.size() +
+ " valid values are: "
+ );
+
+ Enumeration vv = dtdAttribute.values.elements();
+ while (vv.hasMoreElements())
+ {
+ valid.append('"');
+ valid.append(vv.nextElement());
+ valid.append("\" ");
+ }
+ s_error(valid.toString());
+ }
+ }
+
+ private void validateNameOrIdAttribute(TagElement tag, Object foundAttribute,
+ String value
+ )
+ {
+ boolean ok = true;
+
+ if (!Character.isLetter(value.charAt(0)))
+ ok = false;
+
+ char c;
+ for (int i = 0; i < value.length(); i++)
+ {
+ c = value.charAt(i);
+ if (!(
+ Character.isLetter(c) || Character.isDigit(c) ||
+ "".indexOf(c) >= 0
+ )
+ )
+ ok = false;
+ }
+ if (!ok)
+ s_error("The '" + foundAttribute + "' attribute of the tag <" +
+ tag.getHTMLTag() + "> must start from letter and consist of " +
+ "letters, digits, hypens, colons, underscores and periods. " +
+ "It cannot be '" + value + "'"
+ );
+ }
+
+ private void validateNumberAttribute(TagElement tag, Object foundAttribute,
+ String value
+ )
+ {
+ try
+ {
+ Integer.parseInt(value);
+ }
+ catch (NumberFormatException ex)
+ {
+ s_error("The '" + foundAttribute + "' attribute of the tag <" +
+ tag.getHTMLTag() + "> must be a valid number and not '" +
+ value + "'"
+ );
+ }
+ }
+}
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