parser.java

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/* Parser.java

{{IS_NOTE
	Purpose:
		
	Description:
		
	History:
		Sat Sep 17 12:12:41     2005, Created by tomyeh
}}IS_NOTE

Copyright (C) 2004 Potix Corporation. All Rights Reserved.

{{IS_RIGHT
	This program is distributed under GPL Version 2.0 in the hope that
	it will be useful, but WITHOUT ANY WARRANTY.
}}IS_RIGHT
*/
package org.zkoss.web.servlet.dsp.impl;

import java.util.Map;
import java.util.HashMap;
import java.util.Iterator;
import java.io.IOException;
import java.io.FileNotFoundException;
import java.net.URL;
import javax.servlet.jsp.el.FunctionMapper;

import org.zkoss.lang.D;
import org.zkoss.lang.Classes;
import org.zkoss.util.logging.Log;
import org.zkoss.util.resource.Locator;
import org.zkoss.el.SimpleMapper;
import org.zkoss.idom.input.SAXBuilder;
import org.zkoss.idom.Element;
import org.zkoss.idom.util.IDOMs;

import org.zkoss.web.mesg.MWeb;
import org.zkoss.web.servlet.ServletException;
import org.zkoss.web.servlet.dsp.*;
import org.zkoss.web.servlet.dsp.action.Page;
import org.zkoss.web.servlet.dsp.action.Action;

/**
 * Used to parse a DSP page into a meta format called
 * {@link Interpretation}.
 *
 * @author tomyeh
 */
public class Parser {
	private static final Log log = Log.lookup(Parser.class);

	/** Parses the content into a meta format
	 *
	 * @param content the content to parse; never null.
	 * @param ctype the content type. Optional. It is used only if
	 * no page action at all. If it is not specified and not page
	 * action, "text/html" is assumed.
	 * @param fm a pre-defined function mapper, or null to ignore.
	 * @param loc used to locate the resource such as taglib.
	 * It could null only if DSP contains no such resource.
	 */
	public Interpretation parse(String content, String ctype,
	FunctionMapper fm, Locator loc)
	throws javax.servlet.ServletException, IOException {
		final Context ctx = new Context(content, fm, loc);
		final RootNode root = new RootNode(ctx.mapper);
		parse0(ctx, root, 0, content.length());

		if (!ctx.pageDefined) {
			//We always create a page definition
			if (D.ON && log.debugable()) log.debug("Use default content type: "+ctype);
			final ActionNode action = new ActionNode(Page.class, 0);
			root.addChild(0, action);
			final Map attrs = new HashMap(2);
			attrs.put("contentType", ctype != null ? ctype: "text/html");
			applyAttrs("page", action, attrs);
		}

		return root;
	}

	/** Recursively parse the content into a tree of {@link Node}.
	 */
	private static void parse0(Context ctx, Node parent, int from, int to)
	throws javax.servlet.ServletException, IOException {
		boolean esc = false;
		final StringBuffer sb = new StringBuffer(512);
		for (int j = from; j < to; ++j) {
			char cc = ctx.content.charAt(j);
			//We only recognize <%, <\%, ${, $\{ and <xx:yy>
			switch (cc) {
			case '<':
				if (j + 1 < to) {
					char c2 = ctx.content.charAt(j + 1);
					if (c2 == '\\') {
						if (j + 2 < to && ctx.content.charAt(j + 2) == '%')
							++j; //skip '\\'
					} else if (c2 == '%') {
						addText(parent, sb);
						j = parseControl(ctx, parent, j, to);
						continue;
					} else {
						final int oldLines = ctx.nLines;
						int k = skipWhitespaces(ctx, j + 1, to);
						int l = nextSeparator(ctx, k, to);
						if (l >= to || l == k
						|| ctx.content.charAt(l) != ':') {
							ctx.nLines = oldLines;
							break; //bypass what we don't recognize
						}
						final String prefix = ctx.content.substring(k, l);
						if (!ctx.hasPrefix(prefix)) {
							ctx.nLines = oldLines;
							break; //bypass what we don't recognize
						}

						addText(parent, sb);
						j = parseAction(ctx, parent, prefix, l, to);
						continue;
					}
				}
				break;
			case '$':
				if (j + 1 < to) {
					char c2 = ctx.content.charAt(j + 1);
					if (c2 == '\\') {
						if (j + 2 < to && ctx.content.charAt(j + 2) == '{')
							++j; //skip '\\'
					} else if (c2 == '{') {
						addText(parent, sb);
						j = parseEL(ctx, parent, j, to);
						continue;
					}
				}
				break;
			case '\n':
				++ctx.nLines;
			}
			sb.append(cc);
		}
		addText(parent, sb);
	}
	/** Parses a control (e.g., &lt;% page %&gt;) starting at from,
	 * and returns the postion of '&gt' (in %&gt;).
	 */
	private static int parseControl(Context ctx, Node parent,
	int from, int to)
	throws javax.servlet.ServletException, IOException {
		int j = from + 2;
		if (j + 1 >= to)
			throw new ServletException(MWeb.DSP_ACTION_NOT_TERMINATED,
				new Object[] {null, new Integer(ctx.nLines)});

		//0. comment
		char cc = ctx.content.charAt(j);
		if (cc == '-' && ctx.content.charAt(j + 1)  == '-') { //comment
			for (int end = to - 4;; ++j) {
				if (j > end)
					throw new ServletException(MWeb.DSP_COMMENT_NOT_TERMINATED,
						new Integer(ctx.nLines));
				if (ctx.content.charAt(j) == '\n')
					++ctx.nLines;
				else if (startsWith(ctx.content, j, to, "--%>"))
					return j + 3;
			}
		}
		if (cc != '@')
			throw new ServletException(MWeb.DSP_EXPECT_CHARACTER,
				new Object[] {new Character('@'), new Integer(ctx.nLines)});

		//1: which control
		j = skipWhitespaces(ctx, j + 1, to);
		int k = nextSeparator(ctx, j, to);
		if (k >= to)
			throw new ServletException(MWeb.DSP_ACTION_NOT_TERMINATED,
				new Object[] {null, new Integer(ctx.nLines)});
		final ActionNode action;
		final String ctlnm = ctx.content.substring(j, k);
		if ("taglib".equals(ctlnm)) {
			action = null;
		} else if ("page".equals(ctlnm)) {
			ctx.pageDefined = true;
			parent.addChild(action = new ActionNode(Page.class, ctx.nLines));
		} else {
			throw new ServletException(MWeb.DSP_UNKNOWN_ACTION,
				new Object[] {ctlnm, new Integer(ctx.nLines)});
		}

		//2: parse attributes
		final Map attrs = new HashMap();
		k = parseAttrs(ctx, attrs, ctlnm, k, to);
		cc = ctx.content.charAt(k);
		if (cc != '%')
			throw new ServletException(MWeb.DSP_EXPECT_CHARACTER,
				new Object[] {new Character('%'), new Integer(ctx.nLines)});

		if (action == null) { //taglib
			final String uri = (String)attrs.get("uri"),
				prefix = (String)attrs.get("prefix");
			if (prefix == null || uri == null)
				throw new ServletException(MWeb.DSP_TAGLIB_ATTRIBUTE_REQUIRED, new Integer(ctx.nLines));
			ctx.loadTaglib(prefix, uri);
		} else {
			applyAttrs(ctlnm, action, attrs);
		}

		if (++k >= to || ctx.content.charAt(k) != '>')
			throw new ServletException(MWeb.DSP_ACTION_NOT_TERMINATED,
				new Object[] {ctlnm, new Integer(ctx.nLines)});
		return k;
	}

	/** Parses an action (e.g., &lt;c:forEach...&gt;...&lt;/c:forEach&gt;).
	 * @param from the position of ':'
	 * @return the postion of the last '&gt'.
	 */
	private static int parseAction(Context ctx, Node parent,
	String prefix, int from, int to)
	throws javax.servlet.ServletException, IOException {
		//1: which action
		int j = skipWhitespaces(ctx, from + 1, to);
		int k = nextSeparator(ctx, j, to);
		if (k >= to)
			throw new ServletException(MWeb.DSP_ACTION_NOT_TERMINATED,
				new Object[] {prefix+':', new Integer(ctx.nLines)});
		if (k == j)
			throw new ServletException(MWeb.DSP_ACTION_REQUIRED, new Integer(ctx.nLines));

		final String actnm = ctx.content.substring(j, k);
		final Class actcls = ctx.getActionClass(prefix, actnm);
		if (actcls == null)
			throw new ServletException(MWeb.DSP_UNKNOWN_ACTION,
				new Object[] {prefix+':'+actnm, new Integer(ctx.nLines)});
		final ActionNode action = new ActionNode(actcls, ctx.nLines);
		parent.addChild(action);
		if (D.ON && log.debugable()) log.debug("Action "+actnm);

		//2: action's attributes
		final Map attrs = new HashMap();
		j = parseAttrs(ctx, attrs, actnm, k, to);
		char cc = ctx.content.charAt(j);
		boolean ended = cc == '/';
		if (!ended && cc != '>')
			throw new ServletException(MWeb.DSP_UNEXPECT_CHARACTER,
				new Object[] {new Character(cc), new Integer(ctx.nLines)});

		applyAttrs(actnm, action, attrs);

		if (ended) {
			if (j + 1 >= to || ctx.content.charAt(j + 1) != '>')
				throw new ServletException(MWeb.DSP_ACTION_NOT_TERMINATED,
					new Object[] {prefix+':'+actnm, new Integer(action.getLineNumber())});
			return j + 1;
		}