RegexRenderer.java

package org.h3270.render;

/*
 * Copyright (C) 2003-2008 akquinet tech@spree
 *
 * This file is part of h3270.
 *
 * h3270 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 3 of the License, or
 * (at your option) any later version.
 *
 * h3270 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 h3270; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, 
 * MA 02110-1301 USA
 */

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;

import org.h3270.host.InputField;
import org.h3270.host.Screen;
import org.h3270.host.ScreenCharSequence;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.h3270.web.SessionState;

/**
 * @author Andre Spiegel spiegel@gnu.org
 * @version $Id: RegexRenderer.java,v 1.18 2008/11/21 14:48:32 spiegel Exp $
 */
public class RegexRenderer extends HtmlRenderer {
  
  private Pattern acceptPattern = null;
  private Pattern matchPattern  = null;
  private String  htmlTemplate  = null;

  private static final Pattern FILE_PATTERN =
    Pattern.compile (  "^<!-- accept\\n(.*?)\\n^-->\\s+"
                     + "^<!-- match\\n(.*?)\\n^-->\\s+"
                     + "(.*)",
                     Pattern.MULTILINE | Pattern.DOTALL);

  public RegexRenderer (String filename) {
    try {
      BufferedReader input = new BufferedReader (new FileReader (filename));
      StringBuffer   contents = new StringBuffer();
      while (true) {
        String line = input.readLine();
        if (line == null) break;
        contents.append (line);
        contents.append ("\n");
      }
      Matcher m = FILE_PATTERN.matcher (contents);
      if (m.find()) {
        acceptPattern = Pattern.compile (m.group(1));
        matchPattern  = Pattern.compile (m.group(2), Pattern.DOTALL);
        htmlTemplate  = m.group(3);
      } else
        throw new RuntimeException ("could not parse template " + filename);
    } catch (IOException ex) {
      throw new RuntimeException ("IOException while reading " + filename +
                                  " " + ex);
    } 
  }

  public boolean canRender (Screen s) {
    return canRender (new TextRenderer().render(s));
  }
  
  public boolean canRender (String screenText) {
    Matcher m = acceptPattern.matcher (screenText);
    return m.find();
  }
  
  /**
   * Pattern that finds placeholders such as #1, #2, #3 within
   * template pages.  Mind the negative lookbehind at the beginning,
   * because we don't want HTML character references (&#xxx;) to count
   * as placeholders!
   */
  private static final Pattern PLACEHOLDER_PATTERN =
    Pattern.compile ("(?<!&)#([0-9]+)(?:\\{(.*?)\\})?");

  public String render (Screen s, String actionURL, String id) {
    ScreenCharSequence screenSeq = new ScreenCharSequence(s);
    Matcher m = matchPattern.matcher(screenSeq.toString());
    if (m.find()) {
      // Generate HTML page from template, replacing placeholders
      // in the template with matches from the matchPattern.
      StringBuffer result = new StringBuffer();
      result.append ("<form id=\"" + getFormName(id) + "\" "
                     + "action=\"" + actionURL + "\" "
                     + "method=\"post\">\n");
      Matcher placeholder = PLACEHOLDER_PATTERN.matcher (htmlTemplate);
      int index = 0;
      while (placeholder.find()) {
        result.append (htmlTemplate.substring (index, placeholder.start()));
        int number = Integer.parseInt (placeholder.group(1));
        String filterName = placeholder.group(2);
        String replacement = m.group(number);
        if (replacement.startsWith("{"))
          renderInputField (result, 
                            (InputField)screenSeq.getFieldAt(m.start(number)+1),
                            id);
        else if (filterName != null)
          result.append (getFilter(filterName).filter(replacement));
        else
          result.append (replacement);
        
        index = placeholder.end();        
      }
      result.append (htmlTemplate.substring (index));
      result.append ("<div><input type=\"hidden\" name=\"key\" /></div>\n");
      if (id != null) {
        result.append ("<div><input type=\"hidden\" name=\"" 
                     + SessionState.TERMINAL + "\" value=\"" 
                     + id + "\"></div>\n");

      }
      result.append ("</form>");
      appendFocus (s, id, result);
      return result.toString();
    } else
      return "no match";
  }
  
  public String render (Screen s) {
    return this.render (s, "");
  }
  
  private Filter getFilter (String name) {
    try {
      ClassLoader cl = Thread.currentThread().getContextClassLoader();
      Class clz = cl.loadClass(name);
      Filter result = (Filter)clz.newInstance();
      return result;
    } catch (Exception ex) {
      throw new RuntimeException ("error: " + ex);
    }
  }
  
//  public static void main(String[] args) {
//    String path = "/home/spiegel/com/h3270/";
//    RegexRenderer r = new RegexRenderer
//      (path + "templates/dr-tpx.html");
//    Screen s = new S3270Screen(path + "dump/dr-1.edump");
//    if (r.canRender(s))
//      System.out.println(r.render(s));
//    else
//      System.out.println("no match");
//  }
    

}