gapbuf.h File Reference

A dynamic text buffer implementing the gap buffer algorithm. More...

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Classes
struct	gapbuf

Functions
void	gapbuf_assign (struct gapbuf *const o_gap)
	initialize gapbuf object More...
void	gapbuf_discharge (struct gapbuf *const io_gap)
	release resources held by object More...
int	gapbuf_backspace (struct gapbuf *const io_gap, size_t const i_offset)
	perform a backspace operation More...
int	gapbuf_insert (struct gapbuf *const io_gap, size_t const i_offset, unsigned char const i_char)
	insert a character More...
int	gapbuf_delete (struct gapbuf *const io_gap, size_t const i_offset)
	delete a character More...
unsigned char __FAR *	gapbuf_char_next (size_t *io_offset, struct gapbuf const *const i_gap)
	move to next character More...
unsigned char __FAR *	gapbuf_char_prev (size_t *io_offset, struct gapbuf const *const i_gap)
	move to previous character More...
unsigned char __FAR *	gapbuf_line_next (size_t *io_offset, struct gapbuf const *const i_gap)
	move to next line More...
unsigned char __FAR *	gapbuf_line_prev (size_t *io_offset, struct gapbuf const *const i_gap)
	move to previous line More...
int	gapbuf_overwrite (struct gapbuf *const io_gap, size_t const i_offset, unsigned char const i_char)
	overwrite character More...
unsigned char const __FAR *	gapbuf_text (struct gapbuf *const io_gap)
	get the text buffer More...
unsigned char __FAR *	gapbuf_ptr (struct gapbuf const *const i_gap, size_t const i_offset)
	get the text buffer More...

Detailed Description

A dynamic text buffer implementing the gap buffer algorithm.

A cursor (point) is not provided, it must be maintained externally. Routines taking a cursor expect it to be within normal boundaries of the buffer.

See also

edit

Function Documentation

gapbuf_assign()

void gapbuf_assign

(

struct gapbuf *const

o_gap

)

initialize gapbuf object

Parameters

[out]

o_gap

gapbuf object

Returns

none

Memory is not allocated to the gap buffer until a character is inserted.

gapbuf_backspace()

int gapbuf_backspace	(	struct gapbuf *const	io_gap,
		size_t const	i_offset
	)

perform a backspace operation

Parameters

[in,out]	io_gap	gap buffer object
[in]	i_offset	cursor location to perform backspace

Returns

0 operation could not be performed

!0 operation performed

gapbuf_char_next()

unsigned char __FAR * gapbuf_char_next	(	size_t *	io_offset,
		struct gapbuf const *const	i_gap
	)

move to next character

Parameters

[in,out]	io_offset	cursor to advance
[in]	i_gap	gap buffer object

Returns

0 end of file

!0 pointer to next character in the buffer

gapbuf_char_prev()

unsigned char __FAR * gapbuf_char_prev	(	size_t *	io_offset,
		struct gapbuf const *const	i_gap
	)

move to previous character

Parameters

[in,out]	io_offset	cursor to decrement
[in]	i_gap	gap buffer object

Returns

0 beginning of file

!0 previous character

gapbuf_delete()

int gapbuf_delete	(	struct gapbuf *const	io_gap,
		size_t const	i_offset
	)

delete a character

Parameters

[in,out]	io_gap	gap buffer oject
[in]	i_offset	cursor location to perform delete

Returns

0 operation could not be performed

!0 operation performed

gapbuf_discharge()

void gapbuf_discharge

(

struct gapbuf *const

io_gap

)

release resources held by object

Parameters

[in,out]

io_gap

object to release

Returns

none

gapbuf_insert()

int gapbuf_insert	(	struct gapbuf *const	io_gap,
		size_t const	i_offset,
		unsigned char const	i_char
	)

insert a character

Parameters

[in,out]	io_gap	gap buffer oject
[in]	i_offset	cursor location to perform insert
[in]	i_char	character to insert

Returns

0 operation could not be performed

!0 operation performed

gapbuf_line_next()

unsigned char __FAR * gapbuf_line_next	(	size_t *	io_offset,
		struct gapbuf const *const	i_gap
	)

move to next line

Parameters

[in,out]	io_offset	cursor to advance
[in]	i_gap	gap buffer object

Returns

0 end of file

!0 beginning of next line

gapbuf_line_prev()

unsigned char __FAR * gapbuf_line_prev	(	size_t *	io_offset,
		struct gapbuf const *const	i_gap
	)

move to previous line

Parameters

[in,out]	io_offset	cursor to decrement
[in]	i_gap	gap buffer object

Returns

0 beginning of file

!0 beginning of previous line

gapbuf_overwrite()

int gapbuf_overwrite	(	struct gapbuf *const	io_gap,
		size_t const	i_offset,
		unsigned char const	i_char
	)

overwrite character

Parameters

[in,out]	io_gap	gap buffer object
[in]	i_offset	cursor location to preform overwrite
[in]	i_char	character to overwrite

Returns

0 operation could not be performed

!0 character overwritten

gapbuf_ptr()

unsigned char __FAR * gapbuf_ptr	(	struct gapbuf const *const	i_gap,
		size_t const	i_offset
	)

get the text buffer

Parameters

[in]	i_gap	gap buffer object
[in]	i_offset	cursor location

Returns

0 buffer empty or invalid cursor location

!0 pointer to buffer

The routine does not move the gap. The returned address points to either before the start of the gap or after the end of the gap.

gapbuf_text()

unsigned char const __FAR * gapbuf_text

(

struct gapbuf *const

io_gap

)

get the text buffer

Parameters

[in,out]

io_gap

gap buffer object

Returns

0 buffer empty

!0 pointer to buffer

The routine will move the gap so the buffer can be accessed sequentially.

Buffer contents should not be modified.

The returned address is only valid until the next operation that affects the gap.