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* gnu/regexp/CharIndexed.java
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* Copyright (C) 1998-2001 Wes Biggs
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* This library is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published
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* by the Free Software Foundation; either version 2.1 of the License, or
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* (at your option) any later version.
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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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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* @author <A HREF="mailto:wes@cacas.org">Wes Biggs</A>
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public interface CharIndexed {
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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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char OUT_OF_BOUNDS = '\uFFFF';
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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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* @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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char charAt(int index);
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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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boolean move(int index);
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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.