Module ansi 

ANSI escape sequence generation helpers.

This module provides pure byte-generation functions for ANSI/VT control sequences. It handles the encoding details so the Presenter can focus on state tracking and diffing.

Design Principles

• Pure functions: No state tracking, just byte generation
• Zero allocation: Use stack buffers for common sequences
• Explicit: Readable helpers over clever formatting

Sequence Reference

Category	Sequence	Description
CSI	ESC [ n m	SGR (Select Graphic Rendition)
CSI	ESC [ row ; col H	CUP (Cursor Position, 1-indexed)
CSI	ESC [ n K	EL (Erase Line)
CSI	ESC [ n J	ED (Erase Display)
CSI	ESC [ top ; bottom r	DECSTBM (Set Scroll Region)
CSI	ESC [ ? 2026 h/l	Synchronized Output (DEC)
OSC	ESC ] 8 ; ; url ST	Hyperlink (OSC 8)
DEC	ESC 7 / ESC 8	Cursor save/restore (DECSC/DECRC)

Structs

SgrCodes

SGR attribute codes for style flags.

Enums

EraseDisplayMode

ED (Erase Display) mode.

EraseLineMode

EL (Erase Line) mode.

Constants

ALT_SCREEN_ENTER

Enable alternate screen: CSI ? 1049 h

ALT_SCREEN_LEAVE

Disable alternate screen: CSI ? 1049 l

BRACKETED_PASTE_DISABLE

Disable bracketed paste: CSI ? 2004 l

BRACKETED_PASTE_ENABLE

Enable bracketed paste: CSI ? 2004 h

CURSOR_HIDE

Hide cursor: CSI ? 25 l

CURSOR_RESTORE

DEC cursor restore: ESC 8 (DECRC)

CURSOR_SAVE

DEC cursor save: ESC 7 (DECSC)

CURSOR_SHOW

Show cursor: CSI ? 25 h

FLAG_TABLE

Ordered table of (flag, on/off codes) for iteration.

FOCUS_DISABLE

Disable focus reporting: CSI ? 1004 l

FOCUS_ENABLE

Enable focus reporting: CSI ? 1004 h

MOUSE_DISABLE

Disable mouse reporting and clear legacy/alternate modes.

MOUSE_ENABLE

Enable SGR mouse reporting with mode-hygiene pre-reset:

RESET_SCROLL_REGION

Reset scroll region to full screen: CSI r

SGR_BLINK

SGR codes for blink (on=5, off=25).

SGR_BOLD

SGR codes for bold (on=1, off=22).

SGR_DIM

SGR codes for dim (on=2, off=22).

SGR_HIDDEN

SGR codes for hidden text (on=8, off=28).

SGR_ITALIC

SGR codes for italic (on=3, off=23).

SGR_RESET

SGR reset: CSI 0 m

SGR_REVERSE

SGR codes for reverse video (on=7, off=27).

SGR_STRIKETHROUGH

SGR codes for strikethrough (on=9, off=29).

SGR_UNDERLINE

SGR codes for underline (on=4, off=24).

SYNC_BEGIN

Begin synchronized output: CSI ? 2026 h

SYNC_END

End synchronized output: CSI ? 2026 l

Functions

alt_screen_enter

Write alternate screen enter.

alt_screen_leave

Write alternate screen leave.

bracketed_paste_disable

Write bracketed paste disable.

bracketed_paste_enable

Write bracketed paste enable.

cha

CUP to column only: CSI col G (1-indexed)

cr

Move cursor to start of line: \r (CR)

cub

Move cursor back (left): CSI n D

cud

Move cursor down: CSI n B

cuf

Move cursor forward (right): CSI n C

cup

CUP (Cursor Position): CSI row ; col H (1-indexed)

cursor_hide

Write hide cursor.

cursor_restore

Write cursor restore (DECRC).

cursor_save

Write cursor save (DECSC).

cursor_show

Write show cursor.

cuu

Move cursor up: CSI n A

erase_display

ED (Erase Display): CSI n J

erase_line

EL (Erase Line): CSI n K

focus_disable

Write focus disable.

focus_enable

Write focus enable.

hyperlink_end

Close an OSC 8 hyperlink.

hyperlink_start

Open an OSC 8 hyperlink.

hyperlink_start_with_id

Open an OSC 8 hyperlink with an ID parameter.

lf

Move cursor down one line: \n (LF)

mouse_disable

Write mouse disable.

mouse_enable

Write mouse enable.

reset_scroll_region

Write reset scroll region.

set_scroll_region

DECSTBM (Set Top and Bottom Margins): CSI top ; bottom r

sgr_bg_16

Write SGR sequence for 16-color background.

sgr_bg_256

Write SGR sequence for 256-color background: CSI 48;5;n m

sgr_bg_default

Write SGR default background: CSI 49 m

sgr_bg_packed

Write SGR for a PackedRgba color as background (true color).

sgr_bg_rgb

Write SGR sequence for true color background: CSI 48;2;r;g;b m

sgr_codes_for_flag

Get SGR codes for a style flag.

sgr_fg_16

Write SGR sequence for 16-color foreground.

sgr_fg_256

Write SGR sequence for 256-color foreground: CSI 38;5;n m

sgr_fg_default

Write SGR default foreground: CSI 39 m

sgr_fg_packed

Write SGR for a PackedRgba color as foreground (true color).

sgr_fg_rgb

Write SGR sequence for true color foreground: CSI 38;2;r;g;b m

sgr_flags

Write SGR sequence for style flags (all set flags).

sgr_flags_off

Write SGR sequence to turn off specific style flags.

sgr_reset

Write SGR reset sequence.

sync_begin

Write synchronized output begin.

sync_end

Write synchronized output end.