Terminal control/Restricted width positional input/With wrapping

From Rosetta Code
Terminal control/Restricted width positional input/With wrapping is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

Create a routine to obtain data entry using a specific place on the terminal screen. Data entry fields should be restricted to a specific length, and the cursor should not move beyond the input length.

The routine should accept parameters for row number, column number and input length, and should obtain a string value entered by the user.

For the purpose of this task, obtain input from the user, showing data entry at row 3, column 5, with input width restricted to a maximum of 8 characters.

Note: In this task input wrapping is allowed. If the length of input exceeds the maximum width, the left hand side of the field should disappear, allowing additional input to be obtained. However, the cursor must not move beyond the designated input length.

It is permissible to use navigation keys to see input field length.

(See Terminal control/Restricted width positional input/No wrapping for similar input routine with no wrapping).

For a similar task using a graphical user interface, see Graphical User Interface/Restricted width positional input/With wrapping.

Go[edit]

Works with: Windows 10
Translation of: Kotlin


This uses _getch() rather than _getwch() as only ASCII is supported.

package main
 
/*
#include <windows.h>
#include <conio.h>
*/

import "C"
import (
"fmt"
"os"
"os/exec"
)
 
var conOut = C.GetStdHandle(C.STD_OUTPUT_HANDLE)
 
func setCursor(p C.COORD) {
C.SetConsoleCursorPosition(conOut, p)
}
 
func cls() {
cmd := exec.Command("cmd", "/c", "cls")
cmd.Stdout = os.Stdout
cmd.Run()
}
 
func getInput(row, col, width int) string {
if row < 0 || row > 20 || col < 0 || width < 1 || width > 78 || col > (79 - width) {
panic("Invalid parameter(s) to getInput. Terminating program")
}
coord := C.COORD{C.short(col), C.short(row)}
setCursor(coord)
var sb []byte
wlen := 0 // length of text in editing window
full := false
loop:
for {
ch := C._getch() // gets next character, no echo
switch c := byte(ch); c {
case 3, 13:
break loop // break on Ctrl-C or enter key
case 8:
if wlen > 0 { // mimic backspace
fmt.Print("\b \b")
sb = sb[:len(sb) - 1]
wlen--
}
if len(sb) > wlen {
coord.X = C.short(col)
coord.Y = C.short(row)
setCursor(coord)
fmt.Print(string(sb)[len(sb) - width:])
wlen = width
}
case 0, 224:
C._getch() // consume extra character
default:
if c >= 32 && c <= 126 { // echo ascii character, ignore others
sb = append(sb, c)
if !full {
C._putch(ch)
wlen++
} else if len(sb) > wlen {
coord.X = C.short(col)
coord.Y = C.short(row)
setCursor(coord)
fmt.Print(string(sb)[len(sb) - width:])
}
}
}
full = wlen == width // wlen can't exceed width
}
return string(sb)
}
 
func main() {
cls() // clear the console
s := getInput(2, 4, 8) // Windows console row/col numbering starts at 0
coord := C.COORD{0, 22}
setCursor(coord)
fmt.Printf("You entered '%s'\n", s)
}

Kotlin[edit]

Works with: Windows 10

This follows a similar approach to the Kotlin entry for the Terminal control/Restricted width positional input/No wrapping task except, of course, that the code now allows for wrapping.

// Kotlin Native v0.5
 
import kotlinx.cinterop.*
import platform.windows.*
import platform.posix.*
 
val ascii = 32..126
val conOut = GetStdHandle(STD_OUTPUT_HANDLE)!!
 
fun setCursor(p: COORD) = SetConsoleCursorPosition(conOut, p.readValue())
 
fun getInput(row: Short, col: Short, width: Int): String {
require(row in 0..20 && col in 0..(79 - width) && width in 1..78) { "Invalid parameter(s)" }
val coord = nativeHeap.alloc<COORD>().apply { X = col; Y = row }
setCursor(coord)
val sb = StringBuilder(width)
var wlen = 0 // length of text in editing window
var full = false
loop@ while (true) {
val ch = _getwch() // gets next character, no echo
when (ch.toInt()) {
3, 13 -> break@loop // break on Ctrl-C or enter key
 
8 -> { // mimic backspace
if (wlen > 0) {
print("\b \b")
sb.length--
wlen--
}
if (sb.length > wlen) {
coord.apply { X = col; Y = row }
setCursor(coord)
print(sb.toString().takeLast(width))
wlen = width
}
}
 
0, 224 -> _getwch() // consume extra character
 
in ascii -> { // echo ascii character
sb.append(ch.toChar())
if (!full) {
_putwch(ch)
wlen++
}
else if (sb.length > wlen) {
coord.apply { X = col; Y = row }
setCursor(coord)
print(sb.toString().takeLast(width))
}
}
 
else -> {} // igore other characters
}
full = wlen == width // wlen can't exceed width
}
nativeHeap.free(coord)
return sb.toString()
}
 
fun main(args: Array<String>) {
system("cls") // clear the console
val s = getInput(2, 4, 8) // Windows console row/col numbering starts at 0
memScoped {
val coord = alloc<COORD>().apply { X = 0 ; Y = 22 }
setCursor(coord)
}
println("You entered '$s'")
}

Perl 6[edit]

Works with: Rakudo version 2018.10

Should work with any termios compatible terminal.

All printable character keys (except Tab) work, as does backspace and enter. Ctrl-c to exit. All other keys / key-combos are ignored.

use Term::termios;
 
constant $saved = Term::termios.new(fd => 1).getattr;
constant $termios = Term::termios.new(fd => 1).getattr;
# raw mode interferes with carriage returns, so
# set flags needed to emulate it manually
$termios.unset_iflags(<BRKINT ICRNL ISTRIP IXON>);
$termios.unset_lflags(<ECHO ICANON IEXTEN ISIG>);
$termios.setattr(:DRAIN);
 
END {
$saved.setattr(:NOW); # reset terminal to original settings
print "\e[?25h \e[H\e[J"; # clear and reset screen
}
 
my $row = 3;
my $column = 5;
my $field = '';
my $spacer = ' ' x 8;
my $pointer = 0;
 
my ($rows,$cols) = qx/stty size/.words; # get screen size
 
my @screen = "\e[41m{' ' x $cols}\e[0m" xx $rows;
 
update($spacer);
 
loop {
my $key = $*IN.read(4).decode;
given $key {
when ' '..'~' {
if $pointer < 8 {
$field ~= $_;
$spacer = ' ' x 8 - $field.chars;
$pointer +=1;
update($field~$spacer)
} elsif $pointer >= 8 {
$field ~= $_;
$spacer = '';
update($field.substr(*-8))
}
}
when "\c[127]" { # backspace
if $pointer > 0 {
$field.=substr(0,*-1);
$spacer = ' ' x (8 - $field.chars max 0);
$pointer -= 1 if $field.chars < 8;
my $display = $field.chars < 8 ?? $field !! $field.substr(*-8);
update($display~$spacer)
}
}
when "\c[13]" {
update(' ');
print "\e[10;6H\e[1;33;41mYou entered: $field\e[0m\e[$row;{$column}H";
$field = '';
$pointer = 0;
}
when "\c[0003]" { exit } # Ctrl-c
default { }
}
}
 
sub update ($str) {
($rows,$cols) = qx/stty size/.words;
@screen = "\e[41m{' ' x $cols}\e[0m" xx $rows;
print "\e[H\e[J{@screen.join: "\n"}\e[$row;{$column}H$str\e[$row;{$column + $pointer}H";
}

Phix[edit]

function getInput(integer row, col, width)
position(row,col)
string s = ""
while 1 do
integer ch = wait_key()
if ch='\r' then exit end if
if ch='\b' then
if length(s)>0 then
puts(1,"\b \b")
s = s[1..$-1]
end if
if length(s)>=width then
position(row,col)
puts(1,s[-width..-1])
end if
elsif ch>=' ' and ch<='~' then
s &= ch
if length(s)<=width then
puts(1,ch)
else
position(row,col)
puts(1,s[-width..-1])
end if
end if
end while
return s
end function
 
clear_screen() -- clear the console
string s = getInput(3, 5, 8)
position(23,1)
printf(1,"You entered '%s'\n",{s})