85 lines
3.5 KiB
Java
85 lines
3.5 KiB
Java
/* gnu/regexp/CharIndexed.java
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Copyright (C) 1998-2001, 2004 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package gnu.regexp;
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/**
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* Defines the interface used internally so that different types of source
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* text can be accessed in the same way. Built-in concrete classes provide
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* support for String, StringBuffer, InputStream and char[] types.
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* A class that is CharIndexed supports the notion of a cursor within a
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* block of text. The cursor must be able to be advanced via the move()
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* method. The charAt() method returns the character at the cursor position
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* plus a given offset.
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*
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* @author <A HREF="mailto:wes@cacas.org">Wes Biggs</A>
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*/
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public interface CharIndexed {
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/**
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* Defines a constant (0xFFFF was somewhat arbitrarily chosen)
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* that can be returned by the charAt() function indicating that
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* the specified index is out of range.
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*/
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char OUT_OF_BOUNDS = '\uFFFF';
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/**
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* Returns the character at the given offset past the current cursor
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* position in the input. The index of the current position is zero.
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* It is possible for this method to be called with a negative index.
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* This happens when using the '^' operator in multiline matching mode
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* or the '\b' or '\<' word boundary operators. In any case, the lower
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* bound is currently fixed at -2 (for '^' with a two-character newline).
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*
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* @param index the offset position in the character field to examine
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* @return the character at the specified index, or the OUT_OF_BOUNDS
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* character defined by this interface.
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*/
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char charAt(int index);
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/**
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* Shifts the input buffer by a given number of positions. Returns
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* true if the new cursor position is valid.
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*/
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boolean move(int index);
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/**
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* Returns true if the most recent move() operation placed the cursor
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* position at a valid position in the input.
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*/
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boolean isValid();
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}
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