aboutsummaryrefslogtreecommitdiffstats
path: root/trunk/infrastructure/rhino1_7R1/examples/File.java
blob: 62bd980f28431b6c6bdde60f83db50f88d454f8e (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
/* -*- Mode: java; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Rhino code, released
 * May 6, 1998.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1997-2000
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Norris Boyd
 *
 * Alternatively, the contents of this file may be used under the terms of
 * the GNU General Public License Version 2 or later (the "GPL"), in which
 * case the provisions of the GPL are applicable instead of those above. If
 * you wish to allow use of your version of this file only under the terms of
 * the GPL and not to allow others to use your version of this file under the
 * MPL, indicate your decision by deleting the provisions above and replacing
 * them with the notice and other provisions required by the GPL. If you do
 * not delete the provisions above, a recipient may use your version of this
 * file under either the MPL or the GPL.
 *
 * ***** END LICENSE BLOCK ***** */

import org.mozilla.javascript.*;
import java.io.*;
import java.util.Vector;

/**
 * Define a simple JavaScript File object.
 *
 * This isn't intended to be any sort of definitive attempt at a
 * standard File object for JavaScript, but instead is an example
 * of a more involved definition of a host object.
 *
 * Example of use of the File object:
 * <pre>
 * js> defineClass("File")
 * js> file = new File("myfile.txt");
 * [object File]
 * js> file.writeLine("one");                       <i>only now is file actually opened</i>
 * js> file.writeLine("two");
 * js> file.writeLine("thr", "ee");
 * js> file.close();                                <i>must close file before we can reopen for reading</i>
 * js> var a = file.readLines();                    <i>creates and fills an array with the contents of the file</i>
 * js> a;
 * one,two,three
 * js>
 * </pre>
 *
 *
 * File errors or end-of-file signaled by thrown Java exceptions will
 * be wrapped as JavaScript exceptions when called from JavaScript,
 * and may be caught within JavaScript.
 *
 * @author Norris Boyd
 */
public class File extends ScriptableObject {

    /**
     * The zero-parameter constructor.
     *
     * When Context.defineClass is called with this class, it will
     * construct File.prototype using this constructor.
     */
    public File() {
    }

    /**
     * The Java method defining the JavaScript File constructor.
     *
     * If the constructor has one or more arguments, and the
     * first argument is not undefined, the argument is converted
     * to a string as used as the filename.<p>
     *
     * Otherwise System.in or System.out is assumed as appropriate
     * to the use.
     */
    public static Scriptable jsConstructor(Context cx, Object[] args,
                                           Function ctorObj,
                                           boolean inNewExpr)
    {
        File result = new File();
        if (args.length == 0 || args[0] == Context.getUndefinedValue()) {
            result.name = "";
            result.file = null;
        } else {
            result.name = Context.toString(args[0]);
            result.file = new java.io.File(result.name);
        }
        return result;
    }

    /**
     * Returns the name of this JavaScript class, "File".
     */
    public String getClassName() {
        return "File";
    }

    /**
     * Get the name of the file.
     *
     * Used to define the "name" property.
     */
    public String jsGet_name() {
        return name;
    }

    /**
     * Read the remaining lines in the file and return them in an array.
     *
     * Implements a JavaScript function.<p>
     *
     * This is a good example of creating a new array and setting
     * elements in that array.
     *
     * @exception IOException if an error occurred while accessing the file
     *            associated with this object
     */
    public Object jsFunction_readLines()
        throws IOException
    {
        Vector v = new Vector();
        String s;
        while ((s = jsFunction_readLine()) != null) {
            v.addElement(s);
        }
        Object[] lines = new Object[v.size()];
        v.copyInto(lines);

        Scriptable scope = ScriptableObject.getTopLevelScope(this);
        Context cx = Context.getCurrentContext();
        return cx.newObject(scope, "Array", lines);
    }

    /**
     * Read a line.
     *
     * Implements a JavaScript function.
     * @exception IOException if an error occurred while accessing the file
     *            associated with this object, or EOFException if the object
     *            reached the end of the file
     */
    public String jsFunction_readLine() throws IOException {
        return getReader().readLine();
    }

    /**
     * Read a character.
     *
     * @exception IOException if an error occurred while accessing the file
     *            associated with this object, or EOFException if the object
     *            reached the end of the file
     */
    public String jsFunction_readChar() throws IOException {
        int i = getReader().read();
        if (i == -1)
            return null;
        char[] charArray = { (char) i };
        return new String(charArray);
    }

    /**
     * Write strings.
     *
     * Implements a JavaScript function. <p>
     *
     * This function takes a variable number of arguments, converts
     * each argument to a string, and writes that string to the file.
     * @exception IOException if an error occurred while accessing the file
     *            associated with this object
     */
    public static void jsFunction_write(Context cx, Scriptable thisObj,
                                        Object[] args, Function funObj)
        throws IOException
    {
        write0(thisObj, args, false);
    }

    /**
     * Write strings and a newline.
     *
     * Implements a JavaScript function.
     * @exception IOException if an error occurred while accessing the file
     *            associated with this object
     *
     */
    public static void jsFunction_writeLine(Context cx, Scriptable thisObj,
                                            Object[] args, Function funObj)
        throws IOException
    {
        write0(thisObj, args, true);
    }

    public int jsGet_lineNumber()
        throws FileNotFoundException
    {
        return getReader().getLineNumber();
    }

    /**
     * Close the file. It may be reopened.
     *
     * Implements a JavaScript function.
     * @exception IOException if an error occurred while accessing the file
     *            associated with this object
     */
    public void jsFunction_close() throws IOException {
        if (reader != null) {
            reader.close();
            reader = null;
        } else if (writer != null) {
            writer.close();
            writer = null;
        }
    }

    /**
     * Finalizer.
     *
     * Close the file when this object is collected.
     */
    protected void finalize() {
        try {
            jsFunction_close();
        }
        catch (IOException e) {
        }
    }

    /**
     * Get the Java reader.
     */
    public Object jsFunction_getReader() {
        if (reader == null)
            return null;
        // Here we use toObject() to "wrap" the BufferedReader object
        // in a Scriptable object so that it can be manipulated by
        // JavaScript.
        Scriptable parent = ScriptableObject.getTopLevelScope(this);
        return Context.javaToJS(reader, parent);
    }

    /**
     * Get the Java writer.
     *
     * @see File#jsFunction_getReader
     *
     */
    public Object jsFunction_getWriter() {
        if (writer == null)
            return null;
        Scriptable parent = ScriptableObject.getTopLevelScope(this);
        return Context.javaToJS(writer, parent);
    }

    /**
     * Get the reader, checking that we're not already writing this file.
     */
    private LineNumberReader getReader() throws FileNotFoundException {
        if (writer != null) {
            throw Context.reportRuntimeError("already writing file \""
                                             + name
                                             + "\"");
        }
        if (reader == null)
            reader = new LineNumberReader(file == null
                                        ? new InputStreamReader(System.in)
                                        : new FileReader(file));
        return reader;
    }

    /**
     * Perform the guts of write and writeLine.
     *
     * Since the two functions differ only in whether they write a
     * newline character, move the code into a common subroutine.
     *
     */
    private static void write0(Scriptable thisObj, Object[] args, boolean eol)
        throws IOException
    {
        File thisFile = checkInstance(thisObj);
        if (thisFile.reader != null) {
            throw Context.reportRuntimeError("already writing file \""
                                             + thisFile.name
                                             + "\"");
        }
        if (thisFile.writer == null)
            thisFile.writer = new BufferedWriter(
                thisFile.file == null ? new OutputStreamWriter(System.out)
                                      : new FileWriter(thisFile.file));
        for (int i=0; i < args.length; i++) {
            String s = Context.toString(args[i]);
            thisFile.writer.write(s, 0, s.length());
        }
        if (eol)
            thisFile.writer.newLine();
    }

    /**
     * Perform the instanceof check and return the downcasted File object.
     *
     * This is necessary since methods may reside in the File.prototype
     * object and scripts can dynamically alter prototype chains. For example:
     * <pre>
     * js> defineClass("File");
     * js> o = {};
     * [object Object]
     * js> o.__proto__ = File.prototype;
     * [object File]
     * js> o.write("hi");
     * js: called on incompatible object
     * </pre>
     * The runtime will take care of such checks when non-static Java methods
     * are defined as JavaScript functions.
     */
    private static File checkInstance(Scriptable obj) {
        if (obj == null || !(obj instanceof File)) {
            throw Context.reportRuntimeError("called on incompatible object");
        }
        return (File) obj;
    }

    /**
     * Some private data for this class.
     */
    private String name;
    private java.io.File file;  // may be null, meaning to use System.out or .in
    private LineNumberReader reader;
    private BufferedWriter writer;
}