Netscape


1   /*
2    * WebSphinx web-crawling toolkit
3    *
4    * Copyright (c) 1998-2002 Carnegie Mellon University.  All rights
5    * reserved.
6    *
7    * Redistribution and use in source and binary forms, with or without
8    * modification, are permitted provided that the following conditions
9    * are met:
10   *
11   * 1. Redistributions of source code must retain the above copyright
12   *    notice, this list of conditions and the following disclaimer.
13   *
14   * 2. Redistributions in binary form must reproduce the above copyright
15   *    notice, this list of conditions and the following disclaimer in
16   *    the documentation and/or other materials provided with the
17   *    distribution.
18   *
19   * THIS SOFTWARE IS PROVIDED BY CARNEGIE MELLON UNIVERSITY ``AS IS'' AND
20   * ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
21   * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22   * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY
23   * NOR ITS EMPLOYEES BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
24   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
25   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
26   * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
27   * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
28   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
29   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30   *
31   */
32  
33  package websphinx.workbench;
34  
35  import websphinx.*;
36  import java.util.BitSet  ;
37  import java.applet.AppletContext  ;
38  import rcm.util.Str;
39  import netscape.javascript.JSObject;
40  import java.net.URL  ;
41  
42  public class Netscape extends Browser implements ScriptInterpreter {
43  
44      JSObject jsobject;
45          // Javascript interpreter
46      BitSet   applies = new BitSet  ();
47          // n-ary apply functions that have already been made
48  
49      public Netscape (AppletContext   context) {
50          super (context);
51          init ();
52      }
53  
54      public Netscape (AppletContext   context, String   frameName) {
55          super (context, frameName);
56          init ();
57      }
58  
59      private void init () {
60          try {
61              jsobject = JSObject.getWindow (Context.getApplet ());
62          } catch (Throwable   e) {
63              jsobject = null;
64          }
65      }
66  
67      /*
68       * JavaScript interpreter
69       *
70       */
71  
72      public ScriptInterpreter getScriptInterpreter () {
73          return jsobject != null ? this : null;
74      }
75  
76      public String   getLanguage () {
77          return "Javascript";
78      }
79  
80      public Object   eval (String   expression) throws ScriptException {
81          //System.out.println ("evaluating " + expression);
82          if (jsobject == null)
83              throw new ScriptException ("Javascript not available");
84              
85          try {
86              return jsobject.eval (expression);
87          } catch (Throwable   e) {
88              throw new ScriptException (e.getMessage ());
89          }
90      }
91  
92      static String   DBLQUOTE = "\"";
93      static String   LINEFEED = "\n";
94      static String   BACKSLASH = "\\";
95      
96      public Object   lambda (String  [] args, String   body) throws ScriptException {
97          StringBuffer   code = new StringBuffer   ();
98  
99          makeApply (args.length);
100 
101         // Function ("arg0", "arg1", ..., "argn", body)
102         code.append ("Function (");
103         if (args != null)
104             for (int i=0; i<args.length; ++i) {
105                 code.append (DBLQUOTE);
106                 code.append (args[i]);
107                 code.append (DBLQUOTE + ", ");
108             }
109         code.append (DBLQUOTE);
110         
111         body = Str.replace (body, BACKSLASH, BACKSLASH+BACKSLASH);
112         body = Str.replace (body, DBLQUOTE, BACKSLASH+DBLQUOTE);
113         body = Str.replace (body, LINEFEED, BACKSLASH+LINEFEED);
114         code.append (body);
115         code.append (DBLQUOTE + ")");
116 
117         System.out.println ("evaluating\n"+code+"\n");
118         Object   func;
119         synchronized (jsobject) {
120           func = eval (code.toString());
121         }
122         System.out.println ("lambda " + func);
123         return func;
124     }
125 
126     // Create an application function for n-ary functions:
127     //    apply(N+1) = Function ('f', 'a0', 'a1', ..., 'aN-1', 'f (a0, a1, ..., aN-1)')
128     // e.g. apply2 = Function ('f', 'a0', 'f (a0)')
129     void makeApply (int n) {
130         if (applies.get (n))
131             return;
132         applies.set (n);
133 
134         StringBuffer   app = new StringBuffer   ();
135         app.append ("Function ('f', ");
136         for (int i=0; i<n; ++i) {
137             app.append ("'a");
138             app.append (String.valueOf(i));
139             app.append ("',");
140         }
141         app.append ("'return f (");
142         for (int i=0; i<n; ++i) {
143             if (i > 0)
144                 app.append (',');
145             app.append ("a");
146             app.append (String.valueOf(i));
147         }
148         app.append (")')");
149 
150         try {
151             set ("apply" + (n+1), eval (app.toString()));
152         } catch (ScriptException e) {
153             throw new RuntimeException   ("Internal error: cannot create Javascript apply function:\n" + app.toString());
154         }
155     }
156 
157     public Object   apply (Object   func, Object  [] args) throws ScriptException {
158         if (jsobject == null)
159             throw new ScriptException ("Javascript not available");
160             
161         Object  [] funcPlusArgs = new Object  [1 + args.length];
162         funcPlusArgs[0] = func;
163         System.arraycopy (args, 0, funcPlusArgs, 1, args.length);
164         
165         //System.out.print ("applying ");
166         //for (int i=0; i<funcPlusArgs.length; ++i)
167         //    System.out.print (funcPlusArgs + " ");
168         //System.out.println ();
169 
170         Object   result;
171         try {
172           synchronized (jsobject) {
173             result = jsobject.call ("apply" + funcPlusArgs.length, funcPlusArgs);
174           }
175         } catch (Throwable   e) {
176             throw new ScriptException (e.getMessage ());
177         }
178 
179         //System.out.println ("returned " + result);
180         return result;
181     }
182 
183     public void set (String   name, Object   object) {
184         if (jsobject != null)
185           synchronized (jsobject) {
186             jsobject.setMember (name, object);
187           }
188     }
189 
190     public Object   get (String   name) {
191         if (jsobject == null)
192           return null;
193 
194         synchronized (jsobject) {
195             return jsobject.getMember (name);
196         }
197     }
198 
199     /*
200      * Show pages in browser
201      */
202     public void show (URL   url) {
203         // bring the window forward
204         if (frameName != null) {
205             String   code = "window.open ('', '" + frameName + "').focus ()";
206              try {
207                 eval (code);
208             } catch (ScriptException e) {
209                 e.printStackTrace ();
210             }
211         }
212 
213         super.show (url);
214     }
215 }
216
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