v/vlib/readline/readline_lin.v

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// Copyright (c) 2019 Alexander Medvednikov. All rights reserved.
// Use of this source code is governed by an MIT license
// that can be found in the LICENSE file.
// Linux version
// Will serve as more advanced input method
// Based on the work of https://github.com/AmokHuginnsson/replxx
module readline
import term
#include <termios.h>
#include <sys/ioctl.h>
// Used to change the terminal options
struct termios {
mut:
c_iflag int
c_oflag int
c_cflag int
c_lflag int
c_cc [12]int //NCCS == 12. Cant use the defined value here
}
// Used to collect the screen informations
struct winsize {
ws_row u16
ws_col u16
ws_xpixel u16
ws_ypixel u16
}
struct Readline {
mut:
is_raw bool
orig_termios termios
current string // Line being edited
cursor int // Cursor position
overwrite bool
cursor_row_offset int
}
// Defines actions to execute
enum Action {
eof
nothing
insert_character
commit_line
delete_left
delete_right
move_cursor_left
move_cursor_right
move_cursor_begining
move_cursor_end
move_cursor_word_left
move_cursor_word_right
history_previous
history_next
overwrite
clear_screen
}
// Toggle raw mode of the terminal by changing its attributes
pub fn (r mut Readline) enable_raw_mode() {
if ( C.tcgetattr(0, &r.orig_termios) == -1 ) {
panic('No tty')
}
mut raw := r.orig_termios
raw.c_iflag &= ~( C.BRKINT | C.ICRNL | C.INPCK | C.ISTRIP | C.IXON )
raw.c_cflag |= ( C.CS8 )
raw.c_lflag &= ~( C.ECHO | C.ICANON | C.IEXTEN | C.ISIG )
raw.c_cc[C.VMIN] = 1
raw.c_cc[C.VTIME] = 0
C.tcsetattr(0, C.TCSADRAIN, &raw)
r.is_raw = true
}
// Not catching the SIGUSER (CTRL+C) Signal
pub fn (r Readline) enable_raw_mode2() {
if ( C.tcgetattr(0, &r.orig_termios) == -1 ) {
panic('No tty')
}
mut raw := r.orig_termios
raw.c_iflag &= ~( C.BRKINT | C.ICRNL | C.INPCK | C.ISTRIP | C.IXON )
raw.c_cflag |= ( C.CS8 )
raw.c_lflag &= ~( C.ECHO | C.ICANON | C.IEXTEN )
raw.c_cc[C.VMIN] = 1
raw.c_cc[C.VTIME] = 0
C.tcsetattr(0, C.TCSADRAIN, &raw)
}
// Reset back the terminal to its default value
pub fn (r Readline) disable_raw_mode() {
if r.is_raw {
C.tcsetattr(0, C.TCSADRAIN, &r.orig_termios)
}
}
// Read single char
// TODO: Maybe handle UNICODE
fn (r Readline) read_char() byte {
return C.getchar()
}
// Main function of the readline module
// Will loop and ingest characters until EOF or Enter
// Returns the completed line
pub fn (r mut Readline) read_line() string {
r.current = ''
r.cursor = 0
for {
c := r.read_char()
a := r.analyse(c)
if r.execute(a, c) {
break
}
}
return r.current
}
fn (r Readline) analyse(c byte) Action {
switch c {
case `\0`: return Action.eof
case 0x3 : return Action.eof // End of Text
case 0x4 : return Action.eof // End of Transmission
case 255 : return Action.eof
case `\n`: return Action.commit_line
case `\r`: return Action.commit_line
case `\f`: return Action.clear_screen // CTRL + L
case `\b`: return Action.delete_left // Backspace
case 127 : return Action.delete_left // DEL
case 27 : return r.analyse_control() // ESC
case 1 : return Action.move_cursor_begining // ^A
case 5 : return Action.move_cursor_end // ^E
default : return Action.insert_character
}
}
fn (r Readline) analyse_control() Action {
c := r.read_char()
switch c {
case `[`:
sequence := r.read_char()
switch sequence {
case `C`: return Action.move_cursor_right
case `D`: return Action.move_cursor_left
case `E`: return Action.history_next
case `F`: return Action.history_previous
case `1`: return r.analyse_extended_control()
case `3`: return r.analyse_extended_control_no_eat()
}
}
return Action.nothing
}
fn (r Readline) analyse_extended_control() Action {
r.read_char() // Removes ;
c := r.read_char()
switch c {
case `5`:
direction := r.read_char()
switch direction {
case `C`: return Action.move_cursor_word_right
case `D`: return Action.move_cursor_word_left
}
}
return Action.nothing
}
fn (r Readline) analyse_extended_control_no_eat() Action {
c := r.read_char()
switch c {
case `~`: return Action.delete_right // Suppr key
}
return Action.nothing
}
fn (r mut Readline) execute(a Action, c byte) bool {
switch a {
case Action.eof: return true
case Action.insert_character: r.insert_character(c)
case Action.commit_line: return r.commit_line()
case Action.delete_left: r.delete_character()
case Action.delete_right: r.suppr_character()
case Action.move_cursor_left: r.move_cursor_left()
case Action.move_cursor_right: r.move_cursor_right()
case Action.move_cursor_begining: r.move_cursor_begining()
case Action.move_cursor_end: r.move_cursor_end()
case Action.move_cursor_word_left: r.move_cursor_word_left()
case Action.move_cursor_word_right: r.move_cursor_word_right()
case Action.clear_screen: r.clear_screen()
}
return false
}
fn get_screen_columns() int {
ws := winsize{}
cols := if C.ioctl(1, C.TIOCGWINSZ, &ws) == -1 { 80 } else { ws.ws_col }
return int(cols)
}
fn shift_cursor(xpos int, yoffset int) {
if yoffset != 0 {
if yoffset > 0 {
term.cursor_down(yoffset)
}
else {
term.cursor_up(- yoffset)
}
}
// Absolute X position
print('\x1b[${xpos + 1}G')
}
fn calculate_screen_position(x_in int, y_in int, screen_columns int, char_count int, out mut []int) {
mut x := x_in
mut y := y_in
out[0] = x
out[1] = y
for chars_remaining := char_count; chars_remaining > 0; {
chars_this_row := if ( (x + chars_remaining) < screen_columns) { chars_remaining } else { screen_columns - x }
out[0] = x + chars_this_row
out[1] = y
chars_remaining -= chars_this_row
x = 0
y++
}
if out[0] == screen_columns {
out[0] = 0
out[1]++
}
}
// Will redraw the line
fn (r mut Readline) refresh_line() {
mut end_of_input := [0, 0]
calculate_screen_position(0, 0, get_screen_columns(), r.current.len, mut end_of_input)
end_of_input[1] += r.current.count('\n')
mut cursor_pos := [0, 0]
calculate_screen_position(0, 0, get_screen_columns(), r.cursor, mut cursor_pos)
shift_cursor(0, -r.cursor_row_offset)
term.erase_toend()
print(r.current)
if end_of_input[0] == 0 && end_of_input[1] > 0 {
print('\n')
}
shift_cursor(cursor_pos[0], - (end_of_input[1] - cursor_pos[1]))
r.cursor_row_offset = cursor_pos[1]
}
fn (r mut Readline) insert_character(c byte) {
// Small ASCII, to expand
if c >= 127 {
return
}
// TODO: Add character if overwrite at end
if !r.overwrite {
r.current = r.current.left(r.cursor) + c.str() + r.current.right(r.cursor)
} else {
// Overwriting
}
r.cursor++
// Simply print new character if at end of line
// Otherwise refresh the line if cursor != r.current.len
if r.cursor == r.current.len && r.current.len < get_screen_columns() {
print(c.str())
} else {
r.refresh_line()
}
}
// Removes the character behind cursor.
fn (r mut Readline) delete_character() {
if r.cursor <= 0 {
return
}
r.cursor--
r.current = r.current.left(r.cursor) + r.current.right(r.cursor + 1)
r.refresh_line()
}
// Removes the character in front of cursor.
fn (r mut Readline) suppr_character() {
if r.cursor > r.current.len {
return
}
r.current = r.current.left(r.cursor) + r.current.right(r.cursor + 1)
r.refresh_line()
}
// Add a line break then stops the main loop
fn (r mut Readline) commit_line() bool {
r.current = r.current + '\n'
return true
}
fn (r mut Readline) move_cursor_left() {
if r.cursor > 0 {
r.cursor--
r.refresh_line()
}
}
fn (r mut Readline) move_cursor_right() {
if r.cursor < r.current.len {
r.cursor++
r.refresh_line()
}
}
fn (r mut Readline) move_cursor_begining() {
r.cursor = 0
r.refresh_line()
}
fn (r mut Readline) move_cursor_end() {
r.cursor = r.current.len
r.refresh_line()
}
// Check if the character is considered as a word-breaking character
fn (r Readline) is_break_character(c byte) bool {
break_characters := ' \t\v\f\a\b\r\n`~!@#$%^&*()-=+[{]}\\|;:\'",<.>/?'
return break_characters.contains(c.str())
}
fn (r mut Readline) move_cursor_word_left() {
if r.cursor > 0 {
for ; r.cursor > 0 && r.is_break_character(r.current[r.cursor - 1]); r.cursor-- {}
for ; r.cursor > 0 && !r.is_break_character(r.current[r.cursor - 1]); r.cursor-- {}
r.refresh_line()
}
}
fn (r mut Readline) move_cursor_word_right() {
if r.cursor < r.current.len {
for ; r.cursor < r.current.len && r.is_break_character(r.current[r.cursor]); r.cursor++ {}
for ; r.cursor < r.current.len && !r.is_break_character(r.current[r.cursor]); r.cursor++ {}
r.refresh_line()
}
}
fn (r mut Readline) clear_screen() {
term.set_cursor_position(1, 1)
term.erase_clear()
r.refresh_line()
}