Package org.jline.reader.impl

Class BufferImpl

java.lang.Object

org.jline.reader.impl.BufferImpl

All Implemented Interfaces:

Buffer

public class BufferImpl
extends Object
implements Buffer

Default implementation of the Buffer interface.

This class provides a mutable buffer for storing and manipulating the text being edited in the LineReader. It maintains the text content and the current cursor position, and provides methods for text insertion, deletion, and cursor movement.

Key features include:

• Efficient text insertion and deletion with a gap buffer implementation
• Support for Unicode characters beyond the Basic Multilingual Plane
• Cursor movement in both character and line coordinates
• Copy and paste operations
• Secure clearing of buffer contents

The buffer uses a gap buffer data structure for efficient editing operations, which provides good performance for the typical editing patterns in a line editor.

Since:

2.0

See Also:

• Buffer
• LineReader.getBuffer()

Constructor Summary

Constructors

Constructor	Description
BufferImpl()	Creates a new buffer with the default size (64).
BufferImpl(int size)	Creates a new buffer with the specified size.

Method Summary

Modifier and Type	Method	Description
int	atChar(int i)	Returns the character at the specified position in the buffer.
boolean	backspace()	Issue a backspace.
int	backspace(int num)	Issue num backspaces.
boolean	clear()	Clears the buffer content.
BufferImpl	copy()	Creates a copy of this buffer.
void	copyFrom(Buffer buf)	Copies the content and cursor position from another buffer.
int	currChar()	Returns the character at the current cursor position.
boolean	currChar(int ch)	Replaces the character at the current cursor position.
int	cursor()	Returns the current cursor position in the buffer.
boolean	cursor(int position)	Move the cursor position to the specified absolute index.
boolean	delete()	Deletes the character at the cursor position.
int	delete(int num)	Deletes multiple characters starting at the cursor position.
boolean	down()	Moves the cursor down one line while maintaining the same column position if possible.
int	length()	Returns the length of the buffer.
int	move(int num)	Move the cursor where characters.
boolean	moveXY(int dx, int dy)	Moves the cursor by the specified number of columns and rows.
int	nextChar()	Returns the character after the current cursor position.
int	prevChar()	Returns the character before the current cursor position.
String	substring(int start)	Returns a substring of the buffer from the specified start position to the end.
String	substring(int start, int end)	Returns a substring of the buffer from the specified start position to the specified end position.
String	toString()
boolean	up()	Moves the cursor up one line while maintaining the same column position if possible.
String	upToCursor()	Returns a substring of the buffer from the beginning to the current cursor position.
void	write(int c)	Write the specific character into the buffer, setting the cursor position ahead one.
void	write(int c, boolean overTyping)	Write the specific character into the buffer, setting the cursor position ahead one.
void	write(CharSequence str)	Insert the specified chars into the buffer, setting the cursor to the end of the insertion point.
void	write(CharSequence str, boolean overTyping)	Writes a string at the current cursor position and advances the cursor.
void	zeroOut()	Clear any internal buffer.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Details

BufferImpl

public BufferImpl()

Creates a new buffer with the default size (64).

BufferImpl

public BufferImpl(int size)

Creates a new buffer with the specified size.

Parameters:

size - the initial size of the buffer

Method Details

copy

public BufferImpl copy()

Description copied from interface: Buffer

Creates a copy of this buffer.

Specified by:

copy in interface Buffer

Returns:

a new buffer with the same content and cursor position

cursor

public int cursor()

Description copied from interface: Buffer

Returns the current cursor position in the buffer.

Specified by:

cursor in interface Buffer

Returns:

the current cursor position (0-based index)

length

public int length()

Description copied from interface: Buffer

Returns the length of the buffer.

Specified by:

length in interface Buffer

Returns:

the number of characters in the buffer

currChar

public boolean currChar(int ch)

Description copied from interface: Buffer

Replaces the character at the current cursor position.

Specified by:

currChar in interface Buffer

Parameters:

ch - the character to set at the current position

Returns:

true if the buffer was modified

currChar

public int currChar()

Description copied from interface: Buffer

Returns the character at the current cursor position.

Specified by:

currChar in interface Buffer

Returns:

the character at the cursor position, or -1 if the cursor is at the end of the buffer

prevChar

public int prevChar()

Description copied from interface: Buffer

Returns the character before the current cursor position.

Specified by:

prevChar in interface Buffer

Returns:

the character before the cursor position, or -1 if the cursor is at the beginning of the buffer

nextChar

public int nextChar()

Description copied from interface: Buffer

Returns the character after the current cursor position.

Specified by:

nextChar in interface Buffer

Returns:

the character after the cursor position, or -1 if the cursor is at the end of the buffer

atChar

public int atChar(int i)

Description copied from interface: Buffer

Returns the character at the specified position in the buffer.

Specified by:

atChar in interface Buffer

Parameters:

i - the position to check

Returns:

the character at the specified position, or -1 if the position is invalid

write

public void write(int c)

Write the specific character into the buffer, setting the cursor position ahead one.

Specified by:

write in interface Buffer

Parameters:

c - the character to insert

write

public void write(int c,
 boolean overTyping)

Write the specific character into the buffer, setting the cursor position ahead one. The text may overwrite or insert based on the current setting of overTyping.

Specified by:

write in interface Buffer

Parameters:

c - the character to insert

overTyping - if true, overwrites the character at the current position

write

public void write(CharSequence str)

Insert the specified chars into the buffer, setting the cursor to the end of the insertion point.

Specified by:

write in interface Buffer

Parameters:

str - the string to write

write

public void write(CharSequence str,
 boolean overTyping)

Description copied from interface: Buffer

Writes a string at the current cursor position and advances the cursor.

Specified by:

write in interface Buffer

Parameters:

str - the string to write

overTyping - if true, overwrites characters at the current position

clear

public boolean clear()

Description copied from interface: Buffer

Clears the buffer content.

Specified by:

clear in interface Buffer

Returns:

true if the buffer was modified

substring

public String substring(int start)

Description copied from interface: Buffer

Returns a substring of the buffer from the specified start position to the end.

Specified by:

substring in interface Buffer

Parameters:

start - the start index, inclusive

Returns:

the substring

substring

public String substring(int start,
 int end)

Description copied from interface: Buffer

Returns a substring of the buffer from the specified start position to the specified end position.

Specified by:

substring in interface Buffer

Parameters:

start - the start index, inclusive

end - the end index, exclusive

Returns:

the substring

upToCursor

public String upToCursor()

Description copied from interface: Buffer

Returns a substring of the buffer from the beginning to the current cursor position.

Specified by:

upToCursor in interface Buffer

Returns:

the substring

cursor

public boolean cursor(int position)

Move the cursor position to the specified absolute index.

Specified by:

cursor in interface Buffer

Parameters:

position - the position to move the cursor to

Returns:

true if the cursor was moved, false if the position was invalid

move

public int move(int num)

Move the cursor where characters.

Specified by:

move in interface Buffer

Parameters:

num - If less than 0, move abs(where) to the left, otherwise move where to the right.

Returns:

The number of spaces we moved

up

public boolean up()

Description copied from interface: Buffer

Moves the cursor up one line while maintaining the same column position if possible. This is used for multi-line editing.

Specified by:

up in interface Buffer

Returns:

true if the cursor was moved, false if it was already at the first line

down

public boolean down()

Description copied from interface: Buffer

Moves the cursor down one line while maintaining the same column position if possible. This is used for multi-line editing.

Specified by:

down in interface Buffer

Returns:

true if the cursor was moved, false if it was already at the last line

moveXY

public boolean moveXY(int dx,
 int dy)

Description copied from interface: Buffer

Moves the cursor by the specified number of columns and rows. This is used for multi-line editing.

Specified by:

moveXY in interface Buffer

Parameters:

dx - the number of columns to move (positive for right, negative for left)

dy - the number of rows to move (positive for down, negative for up)

Returns:

true if the cursor was moved, false otherwise

backspace

public int backspace(int num)

Issue num backspaces.

Specified by:

backspace in interface Buffer

Parameters:

num - the number of characters to delete

Returns:

the number of characters backed up

backspace

public boolean backspace()

Issue a backspace.

Specified by:

backspace in interface Buffer

Returns:

true if successful

delete

public int delete(int num)

Description copied from interface: Buffer

Deletes multiple characters starting at the cursor position.

Specified by:

delete in interface Buffer

Parameters:

num - the number of characters to delete

Returns:

the number of characters actually deleted

delete

public boolean delete()

Description copied from interface: Buffer

Deletes the character at the cursor position.

Specified by:

delete in interface Buffer

Returns:

true if the buffer was modified

toString

public String toString()

Specified by:

toString in interface Buffer

Overrides:

toString in class Object

copyFrom

public void copyFrom(Buffer buf)

Description copied from interface: Buffer

Copies the content and cursor position from another buffer.

Specified by:

copyFrom in interface Buffer

Parameters:

buf - the buffer to copy from

zeroOut

public void zeroOut()

Description copied from interface: Buffer

Clear any internal buffer.

Specified by:

zeroOut in interface Buffer