Quelle ReadAhead.java Sprache: JAVA

/*
* Copyright (c) 1999, 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.
*
* 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.
*/

/* @test
   @bug 4150737
   @summary Ensure that StreamTokenizer does not read any further ahead
            than is absolutely necessary
*/

import java.io.ByteArrayInputStream;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.io.StreamTokenizer;
import java.io.IOException;

public class ReadAhead {

    /* An InputStream subclass that cannot read past a given limit */
    private static class LimitedInputStream extends InputStream {

        private String input;
        private int limit;      /* Do not allow input[limit] to be read */
        private int next = 0;

        public LimitedInputStream(String input, int limit) {
            this.input = input;
            this.limit = limit;
        }

        public int read() throws IOException {
            if (next >= limit)
                throw new IOException("Attempted to read too far in stream");
            return input.charAt(next++);
        }

    }

    /* A Reader subclass that cannot read past a given limit */
    private static class LimitedReader extends Reader {

        private String input;
        private int limit;      /* Do not allow input[limit] to be read */
        private int next = 0;

        public LimitedReader(String input, int limit) {
            this.input = input;
            this.limit = limit;
        }

        public int read() throws IOException {
            if (next >= limit)
                throw new IOException("Attempted to read too far in stream");
            return input.charAt(next++);
        }

        public int read(char[] b, int off, int len) throws IOException {
            int top = off + len;
            int i;
            for (i = off; i < top; i++) {
                int c = read();
                if (c < 0) break;
                b[i] = (char)c;
            }
            return i - off;
        }

        public void close() { }

    }

    /* Interface for objects that can create new StreamTokenizers
       with a given limited input */
    private static interface StreamTokenizerMaker {
        public StreamTokenizer create(String input, int limit);
    }

    private static void fail(String why) throws Exception {
        throw new Exception(why);
    }

    private static void test(StreamTokenizer st) throws Exception {
        st.eolIsSignificant(true);
        int tt = st.nextToken();
        if (tt != StreamTokenizer.TT_WORD) fail("expected TT_WORD");
        if (!st.sval.equals("foo")) fail("expected word token \"foo\"");
        tt = st.nextToken();
        if (tt != StreamTokenizer.TT_EOL) fail("expected TT_EOL");
    }

    private static void test(StreamTokenizerMaker stm) throws Exception {
        test(stm.create("foo\nx", 4));
        test(stm.create("foo\r\nx", 4));
    }

    public static void main(String[] args) throws Exception {

        /* InputStream case */
        test(new StreamTokenizerMaker() {
            public StreamTokenizer create(String input, int limit) {
                return new StreamTokenizer(new LimitedInputStream(input, limit));
            }});

        /* Reader case */
        test(new StreamTokenizerMaker() {
            public StreamTokenizer create(String input, int limit) {
                return new StreamTokenizer(new LimitedReader(input, limit));
            }});

    }

}

quality86%

¤ Dauer der Verarbeitung: 0.11 Sekunden (vorverarbeitet) ¤

Wurzel

Suchen

Beweissystem der NASA

Beweissystem Isabelle

NIST Cobol Testsuite

Cephes Mathematical Library

Wiener Entwicklungsmethode

Haftungshinweis

Die Informationen auf dieser Webseite wurden nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit, noch Qualität der bereit gestellten Informationen zugesichert.

Bemerkung:

Die farbliche Syntaxdarstellung ist noch experimentell.