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Diffstat (limited to 'libjava/java/io/BufferedReader.java')
| -rw-r--r-- | libjava/java/io/BufferedReader.java | 373 |
1 files changed, 373 insertions, 0 deletions
diff --git a/libjava/java/io/BufferedReader.java b/libjava/java/io/BufferedReader.java new file mode 100644 index 0000000..19e371a --- /dev/null +++ b/libjava/java/io/BufferedReader.java @@ -0,0 +1,373 @@ +/* Copyright (C) 1998, 1999 Cygnus Solutions + + This file is part of libgcj. + +This software is copyrighted work licensed under the terms of the +Libgcj License. Please consult the file "LIBGCJ_LICENSE" for +details. */ + +package java.io; + +/** + * @author Per Bothner <bothner@cygnus.com> + * @date April 22, 1998. + */ +/* Written using "Java Class Libraries", 2nd edition, plus online + * API docs for JDK 1.2 beta from http://www.javasoft.com. + * Status: Believed complete and correct. + */ + +public class BufferedReader extends Reader +{ + Reader in; + char[] buffer; + /* Index of current read position. Must be >= 0 and <= limit. */ + /* There is a special case where pos may be equal to limit+1; this + * is used as an indicator that a readLine was done with a '\r' was + * the very last char in the buffer. Since we don't want to read-ahead + * and potentially block, we set pos this way to indicate the situation + * and deal with it later. Doing it this way rather than having a + * separate boolean field to indicate the condition has the advantage + * that it is self-clearing on things like mark/reset. + */ + int pos; + /* Limit of valid data in buffer. Must be >= pos and <= buffer.length. */ + /* This can be < pos in the one special case described above. */ + int limit; + + /* The value -1 means there is no mark, or the mark has been invalidated. + Otherwise, markPos is the index in the buffer of the marked position. + Must be >= 0 and <= pos. + Note we do not explicitly store the read-limit. + The implicit read-limit is (buffer.length - markPos), which is + guaranteed to be >= the read-limit requested in the call to mark. */ + int markPos = -1; + + public BufferedReader(Reader in) + { + this(in, 8192); + } + + public BufferedReader(Reader in, int size) + { + super(in.lock); + this.in = in; + buffer = new char[size]; + } + + public void close() throws IOException + { + synchronized (lock) + { + if (in != null) + in.close(); + in = null; + buffer = null; + } + } + + public boolean markSupported() + { + return true; + } + + public void mark(int readLimit) throws IOException + { + synchronized (lock) + { + // In this method we need to be aware of the special case where + // pos + 1 == limit. This indicates that a '\r' was the last char + // in the buffer during a readLine. We'll want to maintain that + // condition after we shift things around and if a larger buffer is + // needed to track readLimit, we'll have to make it one element + // larger to ensure we don't invalidate the mark too early, if the + // char following the '\r' is NOT a '\n'. This is ok because, per + // the spec, we are not required to invalidate when passing readLimit. + // + // Note that if 'pos > limit', then doing 'limit -= pos' will cause + // limit to be negative. This is the only way limit will be < 0. + + if (pos + readLimit > limit) + { + char[] old_buffer = buffer; + int extraBuffSpace = 0; + if (pos > limit) + extraBuffSpace = 1; + if (readLimit + extraBuffSpace > limit) + buffer = new char[readLimit + extraBuffSpace]; + limit -= pos; + if (limit >= 0) + { + System.arraycopy(old_buffer, pos, buffer, 0, limit); + pos = 0; + } + } + + if (limit < 0) + { + // Maintain the relationship of 'pos > limit'. + pos = 1; + limit = markPos = 0; + } + else + markPos = pos; + // Now pos + readLimit <= buffer.length. thus if we need to read + // beyond buffer.length, then we are allowed to invalidate markPos. + } + } + + public void reset() throws IOException + { + synchronized (lock) + { + if (markPos < 0) + throw new IOException("mark never set or invalidated"); + + // Need to handle the extremely unlikely case where a readLine was + // done with a '\r' as the last char in the buffer; which was then + // immediately followed by a mark and a reset with NO intervening + // read of any sort. In that case, setting pos to markPos would + // lose that info and a subsequent read would thus not skip a '\n' + // (if one exists). The value of limit in this rare case is zero. + // We can assume that if limit is zero for other reasons, then + // pos is already set to zero and doesn't need to be readjusted. + if (limit > 0) + pos = markPos; + } + } + + public boolean ready() throws IOException + { + synchronized (lock) + { + return pos < limit || in.ready(); + } + } + + public int read(char[] buf, int offset, int count) throws IOException + { + synchronized (lock) + { + // Once again, we need to handle the special case of a readLine + // that has a '\r' at the end of the buffer. In this case, we'll + // need to skip a '\n' if it is the next char to be read. + // This special case is indicated by 'pos > limit'. + boolean retAtEndOfBuffer = false; + + int avail = limit - pos; + if (count > avail) + { + if (avail > 0) + count = avail; + else // pos >= limit + { + if (limit == buffer.length) + markPos = -1; // read too far - invalidate the mark. + if (pos > limit) + { + // Set a boolean and make pos == limit to simplify things. + retAtEndOfBuffer = true; + --pos; + } + if (markPos < 0) + { + // Optimization: can read directly into buf. + if (count >= buffer.length && !retAtEndOfBuffer) + return in.read(buf, offset, count); + pos = limit = 0; + } + avail = in.read(buffer, limit, buffer.length - limit); + if (retAtEndOfBuffer && avail > 0 && buffer[limit] == '\n') + { + --avail; + limit++; + } + if (avail < count) + { + if (avail <= 0) + return avail; + count = avail; + } + limit += avail; + } + } + System.arraycopy(buffer, pos, buf, offset, count); + pos += count; + return count; + } + } + + /* Read more data into the buffer. Update pos and limit appropriatly. + Assumes pos==limit initially. May invalidate the mark if read too much. + Return number of chars read (never 0), or -1 on eof. */ + private int fill() throws IOException + { + // Handle the special case of a readLine that has a '\r' at the end of + // the buffer. In this case, we'll need to skip a '\n' if it is the + // next char to be read. This special case is indicated by 'pos > limit'. + boolean retAtEndOfBuffer = false; + if (pos > limit) + { + retAtEndOfBuffer = true; + --pos; + } + + if (markPos >= 0 && limit == buffer.length) + markPos = -1; + if (markPos <= 0) + pos = limit = 0; + int count = in.read(buffer, limit, buffer.length - limit); + if (count > 0) + limit += count; + + if (retAtEndOfBuffer && buffer[pos] == '\n') + { + --count; + pos++; + } + + return count; + } + + public int read() throws IOException + { + synchronized (lock) + { + if (pos >= limit && fill () <= 0) + return -1; + return buffer[pos++]; + } + } + + /* Return the end of the line starting at this.pos and ending at limit. + * The index returns is *before* any line terminators, or limit + * if no line terminators were found. + */ + private int lineEnd(int limit) + { + int i = pos; + for (; i < limit; i++) + { + char ch = buffer[i]; + if (ch == '\n' || ch == '\r') + break; + } + return i; + } + + public String readLine() throws IOException + { + // Handle the special case where a previous readLine (with no intervening + // reads/skips) had a '\r' at the end of the buffer. + // In this case, we'll need to skip a '\n' if it's the next char to be read. + // This special case is indicated by 'pos > limit'. + if (pos > limit) + { + int ch = read(); + if (ch < 0) + return null; + if (ch != '\n') + --pos; + } + int i = lineEnd(limit); + if (i < limit) + { + String str = new String(buffer, pos, i - pos); + pos = i + 1; + // If the last char in the buffer is a '\r', we must remember + // to check if the next char to be read after the buffer is refilled + // is a '\n'. If so, skip it. To indicate this condition, we set pos + // to be limit + 1, which normally is never possible. + if (buffer[i] == '\r') + if (pos == limit || buffer[pos] == '\n') + pos++; + return str; + } + StringBuffer sbuf = new StringBuffer(200); + sbuf.append(buffer, pos, i - pos); + pos = i; + // We only want to return null when no characters were read before + // EOF. So we must keep track of this separately. Otherwise we + // would treat an empty `sbuf' as an EOF condition, which is wrong + // when there is just a newline. + boolean eof = false; + for (;;) + { + int ch = read(); + if (ch < 0) + { + eof = true; + break; + } + if (ch == '\n' || ch == '\r') + { + // Check here if a '\r' was the last char in the buffer; if so, + // mark it as in the comment above to indicate future reads + // should skip a newline that is the next char read after + // refilling the buffer. + if (ch == '\r') + if (pos == limit || buffer[pos] == '\n') + pos++; + break; + } + i = lineEnd(limit); + sbuf.append(buffer, pos - 1, i - (pos - 1)); + pos = i; + } + return (sbuf.length() == 0 && eof) ? null : sbuf.toString(); + } + + public long skip(long count) throws IOException + { + if (count <= 0) + return 0; + synchronized (lock) + { + // Yet again, we need to handle the special case of a readLine + // that has a '\r' at the end of the buffer. In this case, we need + // to ignore a '\n' if it is the next char to be read. + // This special case is indicated by 'pos > limit' (i.e. avail < 0). + // To simplify things, if we're dealing with the special case for + // readLine, just read the next char (since the fill method will + // skip the '\n' for us). By doing this, we'll have to back up pos. + // That's easier than trying to keep track of whether we've skipped + // one element or not. + int ch; + if (pos > limit) + if ((ch = read()) < 0) + return 0; + else + --pos; + + int avail = limit - pos; + + if (count < avail) + { + pos += count; + return count; + } + + pos = limit; + long todo = count - avail; + if (todo > buffer.length) + { + markPos = -1; + todo -= in.skip(todo); + } + else + { + while (todo > 0) + { + avail = fill(); + if (avail <= 0) + break; + if (avail > todo) + avail = (int) todo; + pos += avail; + todo -= avail; + } + } + return count - todo; + } + } +} |