term: add get_cursor_position and set_terminal_title (#6279)

* added functions

added:
  - get_cursor_position()
  - set_terminal_title(title string)

* implement term.get_cursor_position and term.set_terminal_title on unix

* Cleanup

* make x,y fields of term.Coord mutable

* fix vrepl compilation

* use more descriptive var names in term_test.v

* do not change the current terminal title in dumb terminals; do not test term.set_terminal_title outside of CI

* unix: in term.set_terminal_title, return true even for dumb terminals

Co-authored-by: Brent Pryer <brent@pryermachine.com>
Co-authored-by: Delyan Angelov <delian66@gmail.com>

examples/terminal_control.v

@@ -14,7 +14,7 @@ fn main() {
 fn sleeping_line(x,y,size int, ch string) {
 	mut i := 0
 	for i < size {
-		term.set_cursor_position(x+i,y)
+		term.set_cursor_position(x: x+i, y: y)
 		print(term.bold(term.yellow(ch)))
 		i++
 	}
@@ -23,7 +23,7 @@ fn sleeping_line(x,y,size int, ch string) {
 fn standing_line(x,y,size int, ch string) {
 	mut i := 0
 	for i < size {
-		term.set_cursor_position(x,y+i)
+		term.set_cursor_position(x: x, y: y+i)
 		print(term.bold(term.yellow(ch)))
 		i++
 	}

vlib/readline/readline_linux.c.v

@@ -451,7 +451,7 @@ fn (mut r Readline) switch_overwrite() {
 }
 
 fn (mut r Readline) clear_screen() {
-	term.set_cursor_position(1, 1)
+	term.set_cursor_position(x:1, y:1)
 	term.erase_clear()
 	r.refresh_line()
 }

vlib/term/README.md

@@ -15,9 +15,9 @@ import os
 fn main() {
         term.clear() // clears the content in the terminal
         width, height := term.get_terminal_size() // get the size of the terminal 
-        term.set_cursor_position(width / 2, height / 2) // now we point the cursor to the middle of  the terminal 
+        term.set_cursor_position(x: width / 2, y: height / 2) // now we point the cursor to the middle of  the terminal 
         println(term.strikethrough(term.bright_green("hello world")))  // Print green text
-        term.set_cursor_position(0, height) // Sets the position of the cursor to the bottom of the terminal
+        term.set_cursor_position(x: 0, y: height) // Sets the position of the cursor to the bottom of the terminal
         mut var := os.input('press q to quit: ')
         // Keep prompting until the user presses the q key
         for {
@@ -68,7 +68,7 @@ term.underline(string)
 term.bg_<color>(string)
 
 // sets the position of the cursor at a given place in the terminal
-term.set_cursor_position(x,y)
+term.set_cursor_position(term.Coord)
 
 // moves the cursor up
 term.cursor_up()

vlib/term/control.v

@@ -13,8 +13,8 @@ module term
 // Setting cursor to the given position
 // x is the x coordinate
 // y is the y coordinate
-pub fn set_cursor_position(x int, y int) {
+pub fn set_cursor_position(c Coord) {
-	print('\x1b[$y;$x' + 'H')
+	print('\x1b[$c.y;$c.x' + 'H')
 }
 
 // n is number of cells

vlib/term/term.v

@@ -6,6 +6,14 @@ const (
 	default_columns_size = 80
 	default_rows_size = 25
 )
+
+// Coord - used by term.get_cursor_position and term.set_cursor_position
+pub struct Coord {
+pub mut:
+	x int
+	y int
+}
+
 // can_show_color_on_stdout returns true if colors are allowed in stdout;
 // returns false otherwise.
 pub fn can_show_color_on_stdout() bool {

vlib/term/term_nix.c.v

@@ -3,9 +3,7 @@ module term
 import os
 
 #include <sys/ioctl.h>
-
 #include <termios.h> // TIOCGWINSZ
-
 pub struct C.winsize {
 pub:
 	ws_row    u16
@@ -25,3 +23,71 @@ pub fn get_terminal_size() (int,int) {
 	C.ioctl(1, C.TIOCGWINSZ, &w)
 	return int(w.ws_col), int(w.ws_row)
 }
+
+// get_cursor_position returns a Coord containing the current cursor position
+pub fn get_cursor_position() Coord {
+	if is_atty(1) <= 0 || os.getenv('TERM') == 'dumb' {
+		return Coord{
+			x: 0
+			y: 0
+		}
+	}
+	// TODO: use termios.h, C.tcgetattr & C.tcsetattr directly,
+	// instead of using `stty`
+	oldsettings := os.exec('stty -g') or {
+		os.Result{}
+	}
+	os.system('stty -echo -icanon time 0')
+	print('\033[6n')
+	mut ch := int(0)
+	mut i := 0
+	// ESC [ YYY `;` XXX `R`
+	mut reading_x := false
+	mut reading_y := false
+	mut x := 0
+	mut y := 0
+	for {
+		ch = C.getchar()
+		b := byte(ch)
+		i++
+		assert i < 15
+		// state management:
+		if b == `R` {
+			break
+		}
+		if b == `[` {
+			reading_y = true
+			reading_x = false
+			continue
+		}
+		if b == `;` {
+			reading_y = false
+			reading_x = true
+			continue
+		}
+		// converting string vals to ints:
+		if reading_x {
+			x *= 10
+			x += (b - byte(`0`))
+		}
+		if reading_y {
+			y *= 10
+			y += (b - byte(`0`))
+		}
+	}
+	// restore the old terminal settings:
+	os.system('stty $oldsettings.output')
+	return Coord{
+		x: x
+		y: y
+	}
+}
+
+// set_terminal_title change the terminal title
+pub fn set_terminal_title(title string) bool {
+	if is_atty(1) <= 0 || os.getenv('TERM') == 'dumb' {
+		return true
+	}
+	print('\033]0;${title}\007')
+	return true
+}

vlib/term/term_test.v

@@ -1,3 +1,4 @@
+import os
 import term
 
 fn test_get_terminal_size() {
@@ -55,3 +56,47 @@ fn test_header() {
 	assert term_width == very_long_header_2.len
 	assert term_width == term.header('1234', '_-/\\/\\').len
 }
+
+fn test_get_cursor_position() {
+	original_position := term.get_cursor_position()
+	cursor_position_1 := term.get_cursor_position()
+	assert original_position.x == cursor_position_1.x
+	assert original_position.y == cursor_position_1.y
+	//
+	term.set_cursor_position({
+		x: 10
+		y: 11
+	})
+	cursor_position_2 := term.get_cursor_position()
+	//
+	term.set_cursor_position({
+		x: 5
+		y: 6
+	})
+	cursor_position_3 := term.get_cursor_position()
+	//
+	term.set_cursor_position(original_position)
+	eprintln('original_position: $original_position')
+	eprintln('cursor_position_2: $cursor_position_2')
+	eprintln('cursor_position_3: $cursor_position_3')
+	// 0,0 is returned on dumb terminals
+	if cursor_position_2.x == 0 && cursor_position_2.y == 0 {
+		return
+	}
+	if cursor_position_3.x == 0 && cursor_position_3.y == 0 {
+		return
+	}
+	assert cursor_position_2.x == 10
+	assert cursor_position_2.y == 11
+	assert cursor_position_3.x == 5
+	assert cursor_position_3.y == 6
+}
+
+fn test_set_terminal_title() {
+	// do not change the current terminal title outside of CI:
+	if os.getenv('CI') != 'true' {
+		return
+	}
+	title_change := term.set_terminal_title('v is awesome!')
+	assert title_change == true
+}

vlib/term/term_windows.c.v

@@ -2,7 +2,8 @@ module term
 
 import os
 
-struct Coord {
+pub struct Coord16 {
+pub:
 	x i16
 	y i16
 }
@@ -14,16 +15,22 @@ struct SmallRect {
 	bottom i16
 }
 
+// win: CONSOLE_SCREEN_BUFFER_INFO
+// https://docs.microsoft.com/en-us/windows/console/console-screen-buffer-info-str
 struct ConsoleScreenBufferInfo {
-	dw_size                Coord
+	dw_size                Coord16
-	dw_cursor_position     Coord
+	dw_cursor_position     Coord16
 	w_attributes           u16
 	sr_window              SmallRect
-	dw_maximum_window_size Coord
+	dw_maximum_window_size Coord16
 }
 
+// ref - https://docs.microsoft.com/en-us/windows/console/getconsolescreenbufferinfo
 fn C.GetConsoleScreenBufferInfo(handle os.HANDLE, info &ConsoleScreenBufferInfo) bool
 
+// ref - https://docs.microsoft.com/en-us/windows/console/setconsoletitle
+fn C.SetConsoleTitle(title &u16) bool
+
 // get_terminal_size returns a number of colums and rows of terminal window.
 pub fn get_terminal_size() (int, int) {
 	if is_atty(1) > 0 && os.getenv('TERM') != 'dumb' {
@@ -36,3 +43,22 @@ pub fn get_terminal_size() (int, int) {
 	}
 	return default_columns_size, default_rows_size
 }
+
+// get_cursor_position returns a Coord containing the current cursor position
+pub fn get_cursor_position() Coord {
+	mut res := Coord{}
+	if is_atty(1) > 0 && os.getenv('TERM') != 'dumb' {
+		info := ConsoleScreenBufferInfo{}
+		if C.GetConsoleScreenBufferInfo(C.GetStdHandle(C.STD_OUTPUT_HANDLE), &info) {
+			res.x = info.dw_cursor_position.x
+			res.y = info.dw_cursor_position.y
+		}
+	}
+	return res
+}
+
+// set_terminal_title change the terminal title
+pub fn set_terminal_title(title string) bool {
+	title_change := C.SetConsoleTitle(title.to_wide())
+	return title_change
+}