langtools/src/share/classes/com/sun/tools/doclets/formats/html/markup/HtmlTree.java
changeset 7614 cfadc977ca75
child 7641 8b552db25f99
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/langtools/src/share/classes/com/sun/tools/doclets/formats/html/markup/HtmlTree.java	Wed Dec 01 11:02:38 2010 -0800
@@ -0,0 +1,777 @@
+/*
+ * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code 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
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package com.sun.tools.doclets.formats.html.markup;
+
+import java.util.*;
+import com.sun.tools.doclets.internal.toolkit.Content;
+import com.sun.tools.doclets.internal.toolkit.util.*;
+
+/**
+ * Class for generating HTML tree for javadoc output.
+ *
+ * @author Bhavesh Patel
+ */
+public class HtmlTree extends Content {
+
+    private HtmlTag htmlTag;
+    private Map<HtmlAttr,String> attrs = Collections.<HtmlAttr,String>emptyMap();
+    private List<Content> content = Collections.<Content>emptyList();
+    public static final Content EMPTY = new StringContent("");
+
+    /**
+     * Constructor to construct HtmlTree object.
+     *
+     * @param tag HTML tag for the HtmlTree object
+     */
+    public HtmlTree(HtmlTag tag) {
+        htmlTag = nullCheck(tag);
+    }
+
+    /**
+     * Constructor to construct HtmlTree object.
+     *
+     * @param tag HTML tag for the HtmlTree object
+     * @param contents contents to be added to the tree
+     */
+    public HtmlTree(HtmlTag tag, Content... contents) {
+        this(tag);
+        for (Content content: contents)
+            addContent(content);
+    }
+
+    /**
+     * Adds an attribute for the HTML tag.
+     *
+     * @param attrName name of the attribute
+     * @param attrValue value of the attribute
+     */
+    public void addAttr(HtmlAttr attrName, String attrValue) {
+        if (attrs.isEmpty())
+            attrs = new LinkedHashMap<HtmlAttr,String>();
+        attrs.put(nullCheck(attrName), nullCheck(attrValue));
+    }
+
+    /**
+     * Adds a style for the HTML tag.
+     *
+     * @param style style to be added
+     */
+    public void addStyle(HtmlStyle style) {
+        addAttr(HtmlAttr.CLASS, style.toString());
+    }
+
+    /**
+     * Adds content for the HTML tag.
+     *
+     * @param tagContent tag content to be added
+     */
+    public void addContent(Content tagContent) {
+        if (tagContent == HtmlTree.EMPTY || tagContent.isValid()) {
+            if (content.isEmpty())
+                content = new ArrayList<Content>();
+            content.add(tagContent);
+        }
+    }
+
+    /**
+     * This method adds a string content to the htmltree. If the last content member
+     * added is a StringContent, append the string to that StringContent or else
+     * create a new StringContent and add it to the html tree.
+     *
+     * @param stringContent string content that needs to be added
+     */
+    public void addContent(String stringContent) {
+        if (!content.isEmpty()) {
+            Content lastContent = content.get(content.size() - 1);
+            if (lastContent instanceof StringContent)
+                lastContent.addContent(stringContent);
+            else
+                addContent(new StringContent(stringContent));
+        }
+        else
+            addContent(new StringContent(stringContent));
+    }
+
+    /**
+     * Generates an HTML anchor tag.
+     *
+     * @param ref reference url for the anchor tag
+     * @param body content for the anchor tag
+     * @return an HtmlTree object
+     */
+    public static HtmlTree A(String ref, Content body) {
+        HtmlTree htmltree = new HtmlTree(HtmlTag.A, nullCheck(body));
+        htmltree.addAttr(HtmlAttr.HREF, nullCheck(ref));
+        return htmltree;
+    }
+
+    /**
+     * Generates an HTML anchor tag with name attribute and content.
+     *
+     * @param name name for the anchor tag
+     * @param body content for the anchor tag
+     * @return an HtmlTree object
+     */
+    public static HtmlTree A_NAME(String name, Content body) {
+        HtmlTree htmltree = HtmlTree.A_NAME(name);
+        htmltree.addContent(nullCheck(body));
+        return htmltree;
+    }
+
+    /**
+     * Generates an HTML anchor tag with name attribute.
+     *
+     * @param name name for the anchor tag
+     * @return an HtmlTree object
+     */
+    public static HtmlTree A_NAME(String name) {
+        HtmlTree htmltree = new HtmlTree(HtmlTag.A);
+        htmltree.addAttr(HtmlAttr.NAME, nullCheck(name));
+        return htmltree;
+    }
+
+    /**
+     * Generates a CAPTION tag with some content.
+     *
+     * @param body content for the tag
+     * @return an HtmlTree object for the CAPTION tag
+     */
+    public static HtmlTree CAPTION(Content body) {
+        HtmlTree htmltree = new HtmlTree(HtmlTag.CAPTION, nullCheck(body));
+        return htmltree;
+    }
+
+    /**
+     * Generates a CODE tag with some content.
+     *
+     * @param body content for the tag
+     * @return an HtmlTree object for the CODE tag
+     */
+    public static HtmlTree CODE(Content body) {
+        HtmlTree htmltree = new HtmlTree(HtmlTag.CODE, nullCheck(body));
+        return htmltree;
+    }
+
+    /**
+     * Generates a DD tag with some content.
+     *
+     * @param body content for the tag
+     * @return an HtmlTree object for the DD tag
+     */
+    public static HtmlTree DD(Content body) {
+        HtmlTree htmltree = new HtmlTree(HtmlTag.DD, nullCheck(body));
+        return htmltree;
+    }
+
+    /**
+     * Generates a DL tag with some content.
+     *
+     * @param body content for the tag
+     * @return an HtmlTree object for the DL tag
+     */
+    public static HtmlTree DL(Content body) {
+        HtmlTree htmltree = new HtmlTree(HtmlTag.DL, nullCheck(body));
+        return htmltree;
+    }
+
+    /**
+     * Generates a DIV tag with the style class attributes. It also encloses
+     * a content.
+     *
+     * @param styleClass stylesheet class for the tag
+     * @param body content for the tag
+     * @return an HtmlTree object for the DIV tag
+     */
+    public static HtmlTree DIV(HtmlStyle styleClass, Content body) {
+        HtmlTree htmltree = new HtmlTree(HtmlTag.DIV, nullCheck(body));
+        if (styleClass != null)
+            htmltree.addStyle(styleClass);
+        return htmltree;
+    }
+
+    /**
+     * Generates a DIV tag with some content.
+     *
+     * @param body content for the tag
+     * @return an HtmlTree object for the DIV tag
+     */
+    public static HtmlTree DIV(Content body) {
+        return DIV(null, body);
+    }
+
+    /**
+     * Generates a DT tag with some content.
+     *
+     * @param body content for the tag
+     * @return an HtmlTree object for the DT tag
+     */
+    public static HtmlTree DT(Content body) {
+        HtmlTree htmltree = new HtmlTree(HtmlTag.DT, nullCheck(body));
+        return htmltree;
+    }
+
+    /**
+     * Generates a EM tag with some content.
+     *
+     * @param body content to be added to the tag
+     * @return an HtmlTree object for the EM tag
+     */
+    public static HtmlTree EM(Content body) {
+        HtmlTree htmltree = new HtmlTree(HtmlTag.EM, nullCheck(body));
+        return htmltree;
+    }
+
+    /**
+     * Generates a FRAME tag.
+     *
+     * @param src the url of the document to be shown in the frame
+     * @param name specifies the name of the frame
+     * @param title the title for the frame
+     * @param scrolling specifies whether to display scrollbars in the frame
+     * @return an HtmlTree object for the FRAME tag
+     */
+    public static HtmlTree FRAME(String src, String name, String title, String scrolling) {
+        HtmlTree htmltree = new HtmlTree(HtmlTag.FRAME);
+        htmltree.addAttr(HtmlAttr.SRC, nullCheck(src));
+        htmltree.addAttr(HtmlAttr.NAME, nullCheck(name));
+        htmltree.addAttr(HtmlAttr.TITLE, nullCheck(title));
+        if (scrolling != null)
+            htmltree.addAttr(HtmlAttr.SCROLLING, scrolling);
+        return htmltree;
+    }
+
+    /**
+     * Generates a Frame tag.
+     *
+     * @param src the url of the document to be shown in the frame
+     * @param name specifies the name of the frame
+     * @param title the title for the frame
+     * @return an HtmlTree object for the SPAN tag
+     */
+    public static HtmlTree FRAME(String src, String name, String title) {
+        return FRAME(src, name, title, null);
+    }
+
+    /**
+     * Generates a FRAMESET tag.
+     *
+     * @param cols the size of columns in the frameset
+     * @param rows the size of rows in the frameset
+     * @param title the title for the frameset
+     * @param onload the script to run when the document loads
+     * @return an HtmlTree object for the FRAMESET tag
+     */
+    public static HtmlTree FRAMESET(String cols, String rows, String title, String onload) {
+        HtmlTree htmltree = new HtmlTree(HtmlTag.FRAMESET);
+        if (cols != null)
+            htmltree.addAttr(HtmlAttr.COLS, cols);
+        if (rows != null)
+            htmltree.addAttr(HtmlAttr.ROWS, rows);
+        htmltree.addAttr(HtmlAttr.TITLE, nullCheck(title));
+        htmltree.addAttr(HtmlAttr.ONLOAD, nullCheck(onload));
+        return htmltree;
+    }
+
+    /**
+     * Generates a heading tag (h1 to h6) with the title and style class attributes. It also encloses
+     * a content.
+     *
+     * @param headingTag the heading tag to be generated
+     * @param printTitle true if title for the tag needs to be printed else false
+     * @param styleClass stylesheet class for the tag
+     * @param body content for the tag
+     * @return an HtmlTree object for the tag
+     */
+    public static HtmlTree HEADING(HtmlTag headingTag, boolean printTitle,
+            HtmlStyle styleClass, Content body) {
+        HtmlTree htmltree = new HtmlTree(headingTag, nullCheck(body));
+        if (printTitle)
+            htmltree.addAttr(HtmlAttr.TITLE, Util.stripHtml(body.toString()));
+        if (styleClass != null)
+            htmltree.addStyle(styleClass);
+        return htmltree;
+    }
+
+    /**
+     * Generates a heading tag (h1 to h6) with style class attribute. It also encloses
+     * a content.
+     *
+     * @param headingTag the heading tag to be generated
+     * @param styleClass stylesheet class for the tag
+     * @param body content for the tag
+     * @return an HtmlTree object for the tag
+     */
+    public static HtmlTree HEADING(HtmlTag headingTag, HtmlStyle styleClass, Content body) {
+        return HEADING(headingTag, false, styleClass, body);
+    }
+
+    /**
+     * Generates a heading tag (h1 to h6) with the title attribute. It also encloses
+     * a content.
+     *
+     * @param headingTag the heading tag to be generated
+     * @param printTitle true if the title for the tag needs to be printed else false
+     * @param body content for the tag
+     * @return an HtmlTree object for the tag
+     */
+    public static HtmlTree HEADING(HtmlTag headingTag, boolean printTitle, Content body) {
+        return HEADING(headingTag, printTitle, null, body);
+    }
+
+    /**
+     * Generates a heading tag (h1 to h6)  with some content.
+     *
+     * @param headingTag the heading tag to be generated
+     * @param body content for the tag
+     * @return an HtmlTree object for the tag
+     */
+    public static HtmlTree HEADING(HtmlTag headingTag, Content body) {
+        return HEADING(headingTag, false, null, body);
+    }
+
+    /**
+     * Generates an HTML tag with lang attribute. It also adds head and body
+     * content to the HTML tree.
+     *
+     * @param lang language for the HTML document
+     * @param head head for the HTML tag
+     * @param body body for the HTML tag
+     * @return an HtmlTree object for the HTML tag
+     */
+    public static HtmlTree HTML(String lang, Content head, Content body) {
+        HtmlTree htmltree = new HtmlTree(HtmlTag.HTML, nullCheck(head), nullCheck(body));
+        htmltree.addAttr(HtmlAttr.LANG, nullCheck(lang));
+        return htmltree;
+    }
+
+    /**
+     * Generates a I tag with some content.
+     *
+     * @param body content for the tag
+     * @return an HtmlTree object for the I tag
+     */
+    public static HtmlTree I(Content body) {
+        HtmlTree htmltree = new HtmlTree(HtmlTag.I, nullCheck(body));
+        return htmltree;
+    }
+
+    /**
+     * Generates a LI tag with some content.
+     *
+     * @param body content for the tag
+     * @return an HtmlTree object for the LI tag
+     */
+    public static HtmlTree LI(Content body) {
+        return LI(null, body);
+    }
+
+    /**
+     * Generates a LI tag with some content.
+     *
+     * @param styleClass style for the tag
+     * @param body content for the tag
+     * @return an HtmlTree object for the LI tag
+     */
+    public static HtmlTree LI(HtmlStyle styleClass, Content body) {
+        HtmlTree htmltree = new HtmlTree(HtmlTag.LI, nullCheck(body));
+        if (styleClass != null)
+            htmltree.addStyle(styleClass);
+        return htmltree;
+    }
+
+    /**
+     * Generates a LINK tag with the rel, type, href and title attributes.
+     *
+     * @param rel relevance of the link
+     * @param type type of link
+     * @param href the path for the link
+     * @param title title for the link
+     * @return an HtmlTree object for the LINK tag
+     */
+    public static HtmlTree LINK(String rel, String type, String href, String title) {
+        HtmlTree htmltree = new HtmlTree(HtmlTag.LINK);
+        htmltree.addAttr(HtmlAttr.REL, nullCheck(rel));
+        htmltree.addAttr(HtmlAttr.TYPE, nullCheck(type));
+        htmltree.addAttr(HtmlAttr.HREF, nullCheck(href));
+        htmltree.addAttr(HtmlAttr.TITLE, nullCheck(title));
+        return htmltree;
+    }
+
+    /**
+     * Generates a META tag with the http-equiv, content and charset attributes.
+     *
+     * @param http-equiv http equiv attribute for the META tag
+     * @param content type of content
+     * @param charset character set used
+     * @return an HtmlTree object for the META tag
+     */
+    public static HtmlTree META(String httpEquiv, String content, String charSet) {
+        HtmlTree htmltree = new HtmlTree(HtmlTag.META);
+        htmltree.addAttr(HtmlAttr.HTTP_EQUIV, nullCheck(httpEquiv));
+        htmltree.addAttr(HtmlAttr.CONTENT, nullCheck(content));
+        htmltree.addAttr(HtmlAttr.CHARSET, nullCheck(charSet));
+        return htmltree;
+    }
+
+    /**
+     * Generates a META tag with the name and content attributes.
+     *
+     * @param name name attribute
+     * @param content type of content
+     * @return an HtmlTree object for the META tag
+     */
+    public static HtmlTree META(String name, String content) {
+        HtmlTree htmltree = new HtmlTree(HtmlTag.META);
+        htmltree.addAttr(HtmlAttr.NAME, nullCheck(name));
+        htmltree.addAttr(HtmlAttr.CONTENT, nullCheck(content));
+        return htmltree;
+    }
+
+    /**
+     * Generates a NOSCRIPT tag with some content.
+     *
+     * @param body content of the noscript tag
+     * @return an HtmlTree object for the NOSCRIPT tag
+     */
+    public static HtmlTree NOSCRIPT(Content body) {
+        HtmlTree htmltree = new HtmlTree(HtmlTag.NOSCRIPT, nullCheck(body));
+        return htmltree;
+    }
+
+    /**
+     * Generates a P tag with some content.
+     *
+     * @param body content of the Paragraph tag
+     * @return an HtmlTree object for the P tag
+     */
+    public static HtmlTree P(Content body) {
+        return P(null, body);
+    }
+
+    /**
+     * Generates a P tag with some content.
+     *
+     * @param styleClass style of the Paragraph tag
+     * @param body content of the Paragraph tag
+     * @return an HtmlTree object for the P tag
+     */
+    public static HtmlTree P(HtmlStyle styleClass, Content body) {
+        HtmlTree htmltree = new HtmlTree(HtmlTag.P, nullCheck(body));
+        if (styleClass != null)
+            htmltree.addStyle(styleClass);
+        return htmltree;
+    }
+
+    /**
+     * Generates a SMALL tag with some content.
+     *
+     * @param body content for the tag
+     * @return an HtmlTree object for the SMALL tag
+     */
+    public static HtmlTree SMALL(Content body) {
+        HtmlTree htmltree = new HtmlTree(HtmlTag.SMALL, nullCheck(body));
+        return htmltree;
+    }
+
+    /**
+     * Generates a STRONG tag with some content.
+     *
+     * @param body content for the tag
+     * @return an HtmlTree object for the STRONG tag
+     */
+    public static HtmlTree STRONG(Content body) {
+        HtmlTree htmltree = new HtmlTree(HtmlTag.STRONG, nullCheck(body));
+        return htmltree;
+    }
+
+    /**
+     * Generates a SPAN tag with some content.
+     *
+     * @param body content for the tag
+     * @return an HtmlTree object for the SPAN tag
+     */
+    public static HtmlTree SPAN(Content body) {
+        return SPAN(null, body);
+    }
+
+    /**
+     * Generates a SPAN tag with style class attribute and some content.
+     *
+     * @param styleClass style class for the tag
+     * @param body content for the tag
+     * @return an HtmlTree object for the SPAN tag
+     */
+    public static HtmlTree SPAN(HtmlStyle styleClass, Content body) {
+        HtmlTree htmltree = new HtmlTree(HtmlTag.SPAN, nullCheck(body));
+        if (styleClass != null)
+            htmltree.addStyle(styleClass);
+        return htmltree;
+    }
+
+    /**
+     * Generates a Table tag with border, width and summary attributes and
+     * some content.
+     *
+     * @param border border for the table
+     * @param width width of the table
+     * @param summary summary for the table
+     * @param body content for the table
+     * @return an HtmlTree object for the TABLE tag
+     */
+    public static HtmlTree TABLE(int border, int width, String summary,
+            Content body) {
+        HtmlTree htmltree = new HtmlTree(HtmlTag.TABLE, nullCheck(body));
+        htmltree.addAttr(HtmlAttr.BORDER, Integer.toString(border));
+        htmltree.addAttr(HtmlAttr.WIDTH, Integer.toString(width));
+        htmltree.addAttr(HtmlAttr.SUMMARY, nullCheck(summary));
+        return htmltree;
+    }
+
+    /**
+     * Generates a Table tag with style class, border, cell padding,
+     * cellspacing and summary attributes and some content.
+     *
+     * @param styleClass style of the table
+     * @param border border for the table
+     * @param cellPadding cell padding for the table
+     * @param cellSpacing cell spacing for the table
+     * @param summary summary for the table
+     * @param body content for the table
+     * @return an HtmlTree object for the TABLE tag
+     */
+    public static HtmlTree TABLE(HtmlStyle styleClass, int border, int cellPadding,
+            int cellSpacing, String summary, Content body) {
+        HtmlTree htmltree = new HtmlTree(HtmlTag.TABLE, nullCheck(body));
+        if (styleClass != null)
+            htmltree.addStyle(styleClass);
+        htmltree.addAttr(HtmlAttr.BORDER, Integer.toString(border));
+        htmltree.addAttr(HtmlAttr.CELLPADDING, Integer.toString(cellPadding));
+        htmltree.addAttr(HtmlAttr.CELLSPACING, Integer.toString(cellSpacing));
+        htmltree.addAttr(HtmlAttr.SUMMARY, nullCheck(summary));
+        return htmltree;
+    }
+
+    /**
+     * Generates a Table tag with border, cell padding,
+     * cellspacing and summary attributes and some content.
+     *
+     * @param border border for the table
+     * @param cellPadding cell padding for the table
+     * @param cellSpacing cell spacing for the table
+     * @param summary summary for the table
+     * @param body content for the table
+     * @return an HtmlTree object for the TABLE tag
+     */
+    public static HtmlTree TABLE(int border, int cellPadding,
+            int cellSpacing, String summary, Content body) {
+        return TABLE(null, border, cellPadding, cellSpacing, summary, body);
+    }
+
+    /**
+     * Generates a TD tag with style class attribute and some content.
+     *
+     * @param styleClass style for the tag
+     * @param body content for the tag
+     * @return an HtmlTree object for the TD tag
+     */
+    public static HtmlTree TD(HtmlStyle styleClass, Content body) {
+        HtmlTree htmltree = new HtmlTree(HtmlTag.TD, nullCheck(body));
+        if (styleClass != null)
+            htmltree.addStyle(styleClass);
+        return htmltree;
+    }
+
+    /**
+     * Generates a TD tag for an HTML table with some content.
+     *
+     * @param body content for the tag
+     * @return an HtmlTree object for the TD tag
+     */
+    public static HtmlTree TD(Content body) {
+        return TD(null, body);
+    }
+
+    /**
+     * Generates a TH tag with style class and scope attributes and some content.
+     *
+     * @param styleClass style for the tag
+     * @param scope scope of the tag
+     * @param body content for the tag
+     * @return an HtmlTree object for the TH tag
+     */
+    public static HtmlTree TH(HtmlStyle styleClass, String scope, Content body) {
+        HtmlTree htmltree = new HtmlTree(HtmlTag.TH, nullCheck(body));
+        if (styleClass != null)
+            htmltree.addStyle(styleClass);
+        htmltree.addAttr(HtmlAttr.SCOPE, nullCheck(scope));
+        return htmltree;
+    }
+
+    /**
+     * Generates a TH tag with scope attribute and some content.
+     *
+     * @param scope scope of the tag
+     * @param body content for the tag
+     * @return an HtmlTree object for the TH tag
+     */
+    public static HtmlTree TH(String scope, Content body) {
+        return TH(null, scope, body);
+    }
+
+    /**
+     * Generates a TITLE tag with some content.
+     *
+     * @param body content for the tag
+     * @return an HtmlTree object for the TITLE tag
+     */
+    public static HtmlTree TITLE(Content body) {
+        HtmlTree htmltree = new HtmlTree(HtmlTag.TITLE, nullCheck(body));
+        return htmltree;
+    }
+
+    /**
+     * Generates a TR tag for an HTML table with some content.
+     *
+     * @param body content for the tag
+     * @return an HtmlTree object for the TR tag
+     */
+    public static HtmlTree TR(Content body) {
+        HtmlTree htmltree = new HtmlTree(HtmlTag.TR, nullCheck(body));
+        return htmltree;
+    }
+
+    /**
+     * Generates a UL tag with the style class attribute and some content.
+     *
+     * @param styleClass style for the tag
+     * @param body content for the tag
+     * @return an HtmlTree object for the UL tag
+     */
+    public static HtmlTree UL(HtmlStyle styleClass, Content body) {
+        HtmlTree htmltree = new HtmlTree(HtmlTag.UL, nullCheck(body));
+        htmltree.addStyle(nullCheck(styleClass));
+        return htmltree;
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public boolean isEmpty() {
+        return (!hasContent() && !hasAttrs());
+    }
+
+    /**
+     * Returns true if the HTML tree has content.
+     *
+     * @return true if the HTML tree has content else return false
+     */
+    public boolean hasContent() {
+        return (!content.isEmpty());
+    }
+
+    /**
+     * Returns true if the HTML tree has attributes.
+     *
+     * @return true if the HTML tree has attributes else return false
+     */
+    public boolean hasAttrs() {
+        return (!attrs.isEmpty());
+    }
+
+    /**
+     * Returns true if the HTML tree has a specific attribute.
+     *
+     * @param attrName name of the attribute to check within the HTML tree
+     * @return true if the HTML tree has the specified attribute else return false
+     */
+    public boolean hasAttr(HtmlAttr attrName) {
+        return (attrs.containsKey(attrName));
+    }
+
+    /**
+     * Returns true if the HTML tree is valid. This check is more specific to
+     * standard doclet and not exactly similar to W3C specifications. But it
+     * ensures HTML validation.
+     *
+     * @return true if the HTML tree is valid
+     */
+    public boolean isValid() {
+        switch (htmlTag) {
+            case A :
+                return (hasAttr(HtmlAttr.NAME) || (hasAttr(HtmlAttr.HREF) && hasContent()));
+            case BR :
+                return (!hasContent() && (!hasAttrs() || hasAttr(HtmlAttr.CLEAR)));
+            case FRAME :
+                return (hasAttr(HtmlAttr.SRC) && !hasContent());
+            case HR :
+                return (!hasContent());
+            case IMG :
+                return (hasAttr(HtmlAttr.SRC) && hasAttr(HtmlAttr.ALT) && !hasContent());
+            case LINK :
+                return (hasAttr(HtmlAttr.HREF) && !hasContent());
+            case META :
+                return (hasAttr(HtmlAttr.CONTENT) && !hasContent());
+            default :
+                return hasContent();
+        }
+    }
+
+    /**
+     * Returns true if the element is an inline element.
+     *
+     * @return true if the HTML tag is an inline element
+     */
+    public boolean isInline() {
+        return (htmlTag.blockType == HtmlTag.BlockType.INLINE);
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public void write(StringBuilder contentBuilder) {
+        if (!isInline() && !endsWithNewLine(contentBuilder))
+            contentBuilder.append("\n");
+        String tagString = htmlTag.toString();
+        contentBuilder.append("<" + tagString);
+        Iterator<HtmlAttr> iterator = attrs.keySet().iterator();
+        HtmlAttr key;
+        String value = "";
+        while (iterator.hasNext()) {
+            key = iterator.next();
+            value = attrs.get(key);
+            contentBuilder.append(" " + key.toString());
+            if (!value.isEmpty())
+                contentBuilder.append("=\"" + value + "\"");
+        }
+        contentBuilder.append(">");
+        for (Content c : content)
+            c.write(contentBuilder);
+        if (htmlTag.endTagRequired())
+            contentBuilder.append("</" + tagString + ">");
+        if (!isInline())
+            contentBuilder.append("\n");
+    }
+}