v/vlib/readline/readline_linux.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
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// Based on the work of https://github.com/AmokHuginnsson/replxx
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module readline
import term
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#include <termios.h>
#include <sys/ioctl.h>
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// 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
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clear_screen
suspend
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}
// Toggle raw mode of the terminal by changing its attributes
// Catches SIGUSER (CTRL+C) Signal to reset tty
fn (r mut Readline) enable_raw_mode() {
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if ( C.tcgetattr(0, &r.orig_termios) == -1 ) {
r.is_tty = false
r.is_raw = false
return
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}
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
r.is_tty = true
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}
// Not catching the SIGUSER (CTRL+C) Signal
fn (r mut Readline) enable_raw_mode_nosig() {
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if ( C.tcgetattr(0, &r.orig_termios) == -1 ) {
r.is_tty = false
r.is_raw = false
return
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}
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)
r.is_raw = true
r.is_tty = true
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}
// Reset back the terminal to its default value
fn (r mut Readline) disable_raw_mode() {
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if r.is_raw {
C.tcsetattr(0, C.TCSADRAIN, &r.orig_termios)
r.is_raw = false
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}
}
// Read single char
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fn (r Readline) read_char() int {
return utf8_getchar()
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}
// Main function of the readline module
// Will loop and ingest characters until EOF or Enter
// Returns the completed line as utf8 ustring
// Will return an error if line is empty
pub fn (r mut Readline) read_line_utf8(prompt string) ?ustring {
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r.current = ''.ustring()
r.cursor = 0
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r.prompt = prompt
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r.search_index = 0
r.prompt_offset = get_prompt_offset(prompt)
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if r.previous_lines.len <= 1 {
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r.previous_lines << ''.ustring()
r.previous_lines << ''.ustring()
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}
else {
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r.previous_lines[0] = ''.ustring()
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}
if !r.is_raw {
r.enable_raw_mode()
}
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print(r.prompt)
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for {
c := r.read_char()
a := r.analyse(c)
if r.execute(a, c) {
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break
}
}
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r.previous_lines[0] = ''.ustring()
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r.search_index = 0
r.disable_raw_mode()
if r.current.s == '' {
return error('empty line')
}
return r.current
}
// Returns the string from the utf8 ustring
pub fn (r mut Readline) read_line(prompt string) ?string {
s := r.read_line_utf8(prompt) or {
return error(err)
}
return s.s
}
// Standalone function without persistent functionnalities (eg: history)
// Returns utf8 based ustring
pub fn read_line_utf8(prompt string) ?ustring {
mut r := Readline{}
s := r.read_line_utf8(prompt) or {
return error(err)
}
return s
}
// Standalone function without persistent functionnalities (eg: history)
// Return string from utf8 ustring
pub fn read_line(prompt string) ?string {
mut r := Readline{}
s := r.read_line(prompt) or {
return error(err)
}
return s
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}
fn get_prompt_offset(prompt string) int {
mut len := 0
for i := 0; i < prompt.len; i++ {
if prompt[i] == `\e` {
for ;i < prompt.len && prompt[i] != `m`; i++ {}
} else {
len = len + 1
}
}
return prompt.len - len
}
fn (r Readline) analyse(c int) Action {
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match c {
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`\0` { return .eof }
0x3 { return .eof } // End of Text
0x4 { return .eof } // End of Transmission
255 { return .eof }
`\n` { return .commit_line }
`\r` { return .commit_line }
`\f` { return .clear_screen } // CTRL + L
`\b` { return .delete_left } // Backspace
127 { return .delete_left } // DEL
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27 { return r.analyse_control() } // ESC
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1 { return .move_cursor_begining } // ^A
5 { return .move_cursor_end } // ^E
26 { return .suspend } // CTRL + Z, SUB
else { return if c >= ` ` { Action.insert_character } else { Action.nothing } }
}
}
fn (r Readline) analyse_control() Action {
c := r.read_char()
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match c {
`[` {
sequence := r.read_char()
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match sequence {
`C` { return .move_cursor_right }
`D` { return .move_cursor_left }
`B` { return .history_next }
`A` { return .history_previous }
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`1` { return r.analyse_extended_control() }
`2` { return r.analyse_extended_control_no_eat(sequence) }
`3` { return r.analyse_extended_control_no_eat(sequence) }
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}
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}
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}
return .nothing
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}
fn (r Readline) analyse_extended_control() Action {
r.read_char() // Removes ;
c := r.read_char()
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match c {
`5` {
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direction := r.read_char()
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match direction {
`C` { return .move_cursor_word_right }
`D` { return .move_cursor_word_left }
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}
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}
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}
return .nothing
}
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fn (r Readline) analyse_extended_control_no_eat(last_c byte) Action {
c := r.read_char()
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match c {
`~` {
match last_c {
`3` { return .delete_right } // Suppr key
`2` { return .overwrite }
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}
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}
}
return .nothing
}
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fn (r mut Readline) execute(a Action, c int) bool {
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match a {
.eof { return r.eof() }
.insert_character { r.insert_character(c) }
.commit_line { return r.commit_line() }
.delete_left { r.delete_character() }
.delete_right { r.suppr_character() }
.move_cursor_left { r.move_cursor_left() }
.move_cursor_right { r.move_cursor_right() }
.move_cursor_begining { r.move_cursor_begining() }
.move_cursor_end { r.move_cursor_end() }
.move_cursor_word_left { r.move_cursor_word_left() }
.move_cursor_word_right { r.move_cursor_word_right() }
.history_previous { r.history_previous() }
.history_next { r.history_next() }
.overwrite { r.switch_overwrite() }
.clear_screen { r.clear_screen() }
.suspend { r.suspend() }
}
return false
}
fn get_screen_columns() int {
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ws := Winsize{}
cols := if C.ioctl(1, C.TIOCGWINSZ, &ws) == -1 { 80 } else { int(ws.ws_col) }
return 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]
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calculate_screen_position(r.prompt.len, 0, get_screen_columns(), r.current.len, mut end_of_input)
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end_of_input[1] += r.current.count('\n'.ustring())
mut cursor_pos := [0, 0]
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calculate_screen_position(r.prompt.len, 0, get_screen_columns(), r.cursor, mut cursor_pos)
shift_cursor(0, -r.cursor_row_offset)
term.erase_toend()
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print(r.prompt)
print(r.current)
if end_of_input[0] == 0 && end_of_input[1] > 0 {
print('\n')
}
shift_cursor(cursor_pos[0] - r.prompt_offset, - (end_of_input[1] - cursor_pos[1]))
r.cursor_row_offset = cursor_pos[1]
}
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// End the line without a newline
fn (r mut Readline) eof() bool {
r.previous_lines.insert(1, r.current)
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r.cursor = r.current.len
if r.is_tty {
r.refresh_line()
}
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return true
}
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fn (r mut Readline) insert_character(c int) {
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if !r.overwrite || r.cursor == r.current.len {
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r.current = r.current.left(r.cursor).ustring() + utf32_to_str(u32(c)).ustring() + r.current.right(r.cursor).ustring()
} else {
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r.current = r.current.left(r.cursor).ustring() + utf32_to_str(u32(c)).ustring() + r.current.right(r.cursor + 1).ustring()
}
r.cursor++
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// Refresh the line to add the new character
if r.is_tty {
r.refresh_line()
}
}
// Removes the character behind cursor.
fn (r mut Readline) delete_character() {
if r.cursor <= 0 {
return
}
r.cursor--
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r.current = r.current.left(r.cursor).ustring() + r.current.right(r.cursor + 1).ustring()
r.refresh_line()
}
// Removes the character in front of cursor.
fn (r mut Readline) suppr_character() {
if r.cursor > r.current.len {
return
}
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r.current = r.current.left(r.cursor).ustring() + r.current.right(r.cursor + 1).ustring()
r.refresh_line()
}
// Add a line break then stops the main loop
fn (r mut Readline) commit_line() bool {
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r.previous_lines.insert(1, r.current)
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a := '\n'.ustring()
r.current = r.current + a
r.cursor = r.current.len
if r.is_tty {
r.refresh_line()
println('')
}
return true
}
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fn (r mut Readline) move_cursor_left() {
if r.cursor > 0 {
r.cursor--
r.refresh_line()
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}
}
fn (r mut Readline) move_cursor_right() {
if r.cursor < r.current.len {
r.cursor++
r.refresh_line()
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}
}
fn (r mut Readline) move_cursor_begining() {
r.cursor = 0
r.refresh_line()
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}
fn (r mut Readline) move_cursor_end() {
r.cursor = r.current.len
r.refresh_line()
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}
// Check if the character is considered as a word-breaking character
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fn (r Readline) is_break_character(c string) bool {
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break_characters := ' \t\v\f\a\b\r\n`~!@#$%^&*()-=+[{]}\\|;:\'",<.>/?'
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return break_characters.contains(c)
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}
fn (r mut Readline) move_cursor_word_left() {
if r.cursor > 0 {
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for ; r.cursor > 0 && r.is_break_character(r.current.at(r.cursor - 1)); r.cursor-- {}
for ; r.cursor > 0 && !r.is_break_character(r.current.at(r.cursor - 1)); r.cursor-- {}
r.refresh_line()
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}
}
fn (r mut Readline) move_cursor_word_right() {
if r.cursor < r.current.len {
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for ; r.cursor < r.current.len && r.is_break_character(r.current.at(r.cursor)); r.cursor++ {}
for ; r.cursor < r.current.len && !r.is_break_character(r.current.at(r.cursor)); r.cursor++ {}
r.refresh_line()
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}
}
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fn (r mut Readline) switch_overwrite() {
r.overwrite = !r.overwrite
}
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fn (r mut Readline) clear_screen() {
term.set_cursor_position(1, 1)
term.erase_clear()
r.refresh_line()
}
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fn (r mut Readline) history_previous() {
if r.search_index + 2 >= r.previous_lines.len {
return
}
if r.search_index == 0 {
r.previous_lines[0] = r.current
}
r.search_index++
r.current = r.previous_lines[r.search_index]
r.cursor = r.current.len
r.refresh_line()
}
fn (r mut Readline) history_next() {
if r.search_index <= 0 {
return
}
r.search_index--
r.current = r.previous_lines[r.search_index]
r.cursor = r.current.len
r.refresh_line()
}
fn (r mut Readline) suspend() {
C.raise(C.SIGSTOP)
r.refresh_line()
}