gnu.regexp
Interface CharIndexed

All Known Implementing Classes:

CharIndexedSegment

public interface CharIndexed

Defines the interface used internally so that different types of source text can be accessed in the same way. Built-in concrete classes provide support for String, StringBuffer, InputStream and char[] types. A class that is CharIndexed supports the notion of a cursor within a block of text. The cursor must be able to be advanced via the move() method. The charAt() method returns the character at the cursor position plus a given offset.

Author:

Wes Biggs

Field Summary

static char

OUT_OF_BOUNDS Defines a constant (0xFFFF was somewhat arbitrarily chosen) that can be returned by the charAt() function indicating that the specified index is out of range.

Method Summary

char	charAt(int index) Returns the character at the given offset past the current cursor position in the input.
boolean	isValid() Returns true if the most recent move() operation placed the cursor position at a valid position in the input.
boolean	move(int index) Shifts the input buffer by a given number of positions.

Field Detail

OUT_OF_BOUNDS

public static final char OUT_OF_BOUNDS

Defines a constant (0xFFFF was somewhat arbitrarily chosen) that can be returned by the charAt() function indicating that the specified index is out of range.

See Also:

Constant Field Values

Method Detail

charAt

public char charAt(int index)

Returns the character at the given offset past the current cursor position in the input. The index of the current position is zero. It is possible for this method to be called with a negative index. This happens when using the '^' operator in multiline matching mode or the '\b' or '\<' word boundary operators. In any case, the lower bound is currently fixed at -2 (for '^' with a two-character newline).

Parameters:

index - the offset position in the character field to examine

Returns:

the character at the specified index, or the OUT_OF_BOUNDS character defined by this interface.

move

public boolean move(int index)

Shifts the input buffer by a given number of positions. Returns true if the new cursor position is valid.

isValid

public boolean isValid()

Returns true if the most recent move() operation placed the cursor position at a valid position in the input.