Readline interface
Readline interface 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.
A readline interface is a line editing facility that provides auto completion facilities and the ability to recall previously typed lines. Build a simple application that accepts at least two commands and uses a readline style interface.
The interface should provide
- the ability to recall previously typed commands
- commandline editing
- application specific commands
The application could be based on Simple database or something else.
If the language already provides a readline interface, then it should be demonstrated how build an application specific readline interface (one that only understands the applications commands) and also show how to customize the builtin readline to provide the above features and especially add application specific commands.
See also: Input loop
11l
[String] histArr
F hello()
print(‘Hello World!’)
:histArr [+]= ‘hello’
F hist()
I :histArr.empty
print(‘No history’)
E
L(cmd) :histArr
print(‘ - ’cmd)
:histArr [+]= ‘hist’
F help()
print(‘Available commands:’)
print(‘ hello’)
print(‘ hist’)
print(‘ exit’)
print(‘ help’)
:histArr [+]= ‘help’
[String = (() -> Void)] aa
aa[‘help’] = help
aa[‘hist’] = hist
aa[‘hello’] = hello
print(‘Enter a command, type help for a listing.’)
L
V line = input(‘>’)
I line == ‘exit’
L.break
aa.get(line, help)()C
A program that does absolutely nothing. Type 'help' for help.
#include <readline/readline.h>
#include <readline/history.h>
#include <string.h>
int main()
{
char *s;
using_history();
while (1) {
s = readline("This be a prompt> ");
if (!s || !strcmp(s, "quit")) {
puts("bye.");
return 0;
}
if (!strcmp(s, "help"))
puts("commands: ls, cat, quit");
else if (!strcmp(s, "ls") || !strcmp(s, "cat")) {
printf("command `%s' not implemented yet.\n", s);
add_history(s);
} else
puts("Yes...?");
}
}
C#
using System;
using System.Collections.Generic;
using System.Runtime.CompilerServices;
namespace ReadlineInterface {
class Program {
static LinkedList<string> histArr = new LinkedList<string>();
static void AppendHistory([CallerMemberName] string name = "unknown") {
histArr.AddLast(name);
}
static void Hist() {
if (histArr.Count == 0) {
Console.WriteLine("No history");
}
else {
foreach (string cmd in histArr) {
Console.WriteLine(" - {0}", cmd);
}
}
AppendHistory();
}
static void Hello() {
Console.WriteLine("Hello World!");
AppendHistory();
}
static void Help() {
Console.WriteLine("Available commands:");
Console.WriteLine(" hello");
Console.WriteLine(" hist");
Console.WriteLine(" exit");
Console.WriteLine(" help");
AppendHistory();
}
static void Main(string[] args) {
Dictionary<string, Action> cmdDict = new Dictionary<string, Action>();
cmdDict.Add("help", Help);
cmdDict.Add("hist", Hist);
cmdDict.Add("hello", Hello);
Console.WriteLine("Enter a command, type help for a listing.");
while (true) {
Console.Write(">");
string line = Console.ReadLine();
if (line=="exit") {
break;
}
Action action;
if (cmdDict.TryGetValue(line, out action)) {
action.Invoke();
} else {
Help();
}
}
}
}
}
C++
#include <iostream>
#include <string>
#include <vector>
std::vector<std::string> hist;
std::ostream& operator<<(std::ostream& os, const std::string& str) {
return os << str.c_str();
}
void appendHistory(const std::string& name) {
hist.push_back(name);
}
void hello() {
std::cout << "Hello World!\n";
appendHistory(__func__);
}
void history() {
if (hist.size() == 0) {
std::cout << "No history\n";
} else {
for (auto& str : hist) {
std::cout << " - " << str << '\n';
}
}
appendHistory(__func__);
}
void help() {
std::cout << "Available commands:\n";
std::cout << " hello\n";
std::cout << " hist\n";
std::cout << " exit\n";
std::cout << " help\n";
appendHistory(__func__);
}
int main() {
bool done = false;
std::string cmd;
do {
std::cout << "Enter a command, type help for a listing.\n";
std::cin >> cmd;
for (size_t i = 0; i < cmd.size(); ++i) {
cmd[i] = toupper(cmd[i]);
}
if (strcmp(cmd.c_str(), "HELLO") == 0) {
hello();
} else if (strcmp(cmd.c_str(), "HIST") == 0) {
history();
} else if (strcmp(cmd.c_str(), "EXIT") == 0) {
done = true;
} else {
help();
}
} while (!done);
return 0;
}
D
module readline_interface;
import std.stdio;
import std.string;
alias VOIDF = void function();
void hello() {
writeln("Hello World!");
histArr ~= __FUNCTION__;
}
string[] histArr;
void hist() {
if (histArr.length == 0) {
writeln("No history");
} else {
foreach(cmd; histArr) {
writeln(" - ", cmd);
}
}
histArr ~= __FUNCTION__;
}
void help() {
writeln("Available commands:");
writeln(" hello");
writeln(" hist");
writeln(" exit");
writeln(" help");
histArr ~= __FUNCTION__;
}
void main() {
VOIDF[string] aa;
aa["help"] = &help;
aa["hist"] = &hist;
aa["hello"] = &hello;
writeln("Enter a command, type help for a listing.");
string line;
write(">");
while ((line = readln()) !is null) {
line = chomp(line);
if (line == "exit") {
break;
}
aa.get(line, &help)();
write(">");
}
}
- Output:
Enter a command, type help for a listing. >hist No history >help Available commands: hello hist exit help >hello Hello World! >hist - readline_interface.hist - readline_interface.help - readline_interface.hello >exit
FreeBASIC
Type TypeRL
As String history(100)
As Integer histCount
End Type
Dim Shared As TypeRL ReadLine
Sub AddToHistory(comando As String)
If ReadLine.histCount < 100 Then
ReadLine.history(ReadLine.histCount) = comando
ReadLine.histCount += 1
Else
For i As Integer = 1 To 99
ReadLine.history(i - 1) = ReadLine.history(i)
Next
ReadLine.history(99) = comando
End If
End Sub
Sub PrintHistory()
If ReadLine.histCount = 0 Then
Print !"\nNo history"
Else
Print
For i As Integer = 0 To ReadLine.histCount - 1
Print " - "; ReadLine.history(i)
Next
End If
AddToHistory("hist")
End Sub
Sub PrintHelp()
Print !"\nAvailable commands:"
Print " hello"
Print " hist"
Print " exit"
Print " help"
AddToHistory("help")
End Sub
Sub PrintHello()
Print !"\nHello World!"
AddToHistory("hello")
End Sub
Sub ReadLineStart()
Print "Enter a command, type help for a listing."
Do
Print ">";
Dim As String cmd
Line Input ; cmd
cmd = Trim(Lcase(cmd))
Select Case cmd
Case "exit" : Exit Do
Case "hello" : PrintHello()
Case "hist" : PrintHistory()
Case "help" : PrintHelp()
Case Else : Print !"\nUnknown command, try again"
End Select
Loop
End Sub
ReadLineStart()
- Output:
Same as Wren, Go or Nim entry.
Go
package main
import (
"bufio"
"fmt"
"log"
"os"
"strings"
)
type vf = func()
var history []string
func hello() {
fmt.Println("Hello World!")
history = append(history, "hello")
}
func hist() {
if len(history) == 0 {
fmt.Println("No history")
} else {
for _, cmd := range history {
fmt.Println(" -", cmd)
}
}
history = append(history, "hist")
}
func help() {
fmt.Println("Available commands:")
fmt.Println(" hello")
fmt.Println(" hist")
fmt.Println(" exit")
fmt.Println(" help")
history = append(history, "help")
}
func main() {
scanner := bufio.NewScanner(os.Stdin)
vfs := map[string]vf{"help": help, "hist": hist, "hello": hello}
fmt.Println("Enter a command, type help for a listing.")
for {
fmt.Print(">")
scanner.Scan()
if scerr := scanner.Err(); scerr != nil {
log.Fatal(scerr)
}
line := strings.TrimSpace(scanner.Text())
if line == "exit" {
return
}
cmd, ok := vfs[line]
if !ok {
fmt.Println("Unknown command, try again")
} else {
cmd()
}
}
}
- Output:
Sample session:
Enter a command, type help for a listing. >hit Unknown command, try again >hist No history >help Available commands: hello hist exit help >hello Hello World! >hist - hist - help - hello >exit
Java
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.Map;
public class ReadlineInterface {
private static LinkedList<String> histArr = new LinkedList<>();
private static void hist() {
if (histArr.isEmpty()) {
System.out.println("No history");
} else {
histArr.forEach(cmd -> System.out.printf(" - %s\n", cmd));
}
class Crutch {}
histArr.add(Crutch.class.getEnclosingMethod().getName());
}
private static void hello() {
System.out.println("Hello World!");
class Crutch {}
histArr.add(Crutch.class.getEnclosingMethod().getName());
}
private static void help() {
System.out.println("Available commands:");
System.out.println(" hello");
System.out.println(" hist");
System.out.println(" exit");
System.out.println(" help");
class Crutch {}
histArr.add(Crutch.class.getEnclosingMethod().getName());
}
public static void main(String[] args) throws IOException {
Map<String, Runnable> cmdMap = new HashMap<>();
cmdMap.put("help", ReadlineInterface::help);
cmdMap.put("hist", ReadlineInterface::hist);
cmdMap.put("hello", ReadlineInterface::hello);
BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter a command, type help for a listing.");
while (true) {
System.out.print(">");
String line = in.readLine();
if ("exit".equals(line)) {
break;
}
cmdMap.getOrDefault(line, ReadlineInterface::help).run();
}
}
}
Julia
Simple program that does nothing (copy of C).
function input(prompt::AbstractString)
print(prompt)
r = readline(STDIN)
if isempty(r) || r == "quit"
println("bye.")
elseif r == "help"
println("commands: ls, cat, quit")
elseif r ∈ ("ls", "cat")
println("command `$r` not implemented yet")
else
println("Yes...?")
end
end
input("This is a common prompt> ")
Kotlin
// version 1.0.6
var range = intArrayOf() // empty initially
val history = mutableListOf<String>()
fun greeting() {
ProcessBuilder("cmd", "/c", "cls").inheritIO().start().waitFor() // clears console in windows 10
println("** Welcome to the Ranger readline interface **")
println("** which performs operations on a range of integers **\n")
println("Commands available:")
println(" range [i] [j], help, show, square, cube, add [n], sub [n]")
println(" mul [n], prev, hist, quit")
println()
}
fun setRange(start: Int, end: Int) {
range = IntArray(end - start + 1) { it + start }
show()
}
fun help() {
println(" range [i] [j] - sets the current range to [i, j] and shows them")
println(" - if i > j, sets the current range to the single value [i]")
println(" help - displays help for each command")
println(" show - displays a maximum of 10 values from the current range")
println(" square - sets the current range to their squares and shows them")
println(" cube - sets the current range to their cubes and shows them")
println(" add [i] - adds [i] to the current range and shows them")
println(" sub [i] - subtracts [i] from the current range and shows them")
println(" mul [i] - multiplies the current range by [i] and shows them")
println(" prev - displays previous command entered")
println(" hist - displays a maximum of last 10 commands entered, newest first")
println(" quit - quits Ranger")
println()
println(" < items in square brackets denote integers to be supplied e.g. range 1 5 >")
println(" < right/left arrow keys can be used to scroll through previous commands >")
}
fun show() {
val max = if (range.size > 10) 10 else range.size
val more = range.size - max
for (i in 0 until max) println(" ${range[i]}")
if (more > 0) println(" plus $more more")
}
fun square() {
for (i in 0 until range.size) range[i] *= range[i]
show()
}
fun cube() {
for (i in 0 until range.size) range[i] *= range[i] * range[i]
show()
}
fun add(n: Int) {
for (i in 0 until range.size) range[i] += n
show()
}
fun sub(n: Int) {
for (i in 0 until range.size) range[i] -= n
show()
}
fun mul(n: Int) {
for (i in 0 until range.size) range[i] *= n
show()
}
fun prev() {
if (history.size == 0) println("- No history yet") else println("- ${history.last()}")
}
fun showHistory() {
val size = history.size
if (size == 0) {println("- No history yet"); return}
val max = if (size > 10) 10 else size
val more = size - max
for (i in size - 1 downTo size - max) println("- ${history[i]}")
if (more > 0) println("- plus $more more")
}
fun main(args: Array<String>) {
val r = Regex ("\\s+")
val rangeCommands = arrayOf("show", "square", "cube", "add", "sub", "mul")
greeting()
while (true) {
var command = readLine()!!.trim().toLowerCase()
if (command == "") continue
var i: Int = 0
var j: Int = 0
var addToHistory = true
if (command.startsWith("range")) {
if (command == "range") { println("- Parameters required, try again\n"); continue}
val splits = command.split(r)
if (splits.size == 3) {
try {
i = splits[1].toInt()
j = splits[2].toInt()
if (i > j) j = i
command = "range"
history.add("$command $i $j")
addToHistory = false
}
catch(ex: NumberFormatException) {
}
}
}
else if (command.startsWith("add") || command.startsWith("sub") || command.startsWith("mul")) {
if (command.length == 3) { println("- Parameter required, try again\n"); continue}
val splits2 = command.split(r)
if (splits2.size == 2) {
try {
i = splits2[1].toInt()
command = command.take(3)
history.add("$command $i")
addToHistory = false
}
catch(ex: NumberFormatException) {
}
}
}
if (range.size == 0 && command in rangeCommands) {
println("- Range has not yet been set\n")
if (addToHistory) history.add(command)
continue
}
when (command) {
"range" -> setRange(i, j)
"help" -> help()
"show" -> show()
"square" -> square()
"cube" -> cube()
"add" -> add(i)
"sub" -> sub(i)
"mul" -> mul(i)
"prev" -> prev()
"hist" -> showHistory()
"quit" -> return
else -> {addToHistory = false; println("- Invalid command, try again")}
}
if (addToHistory) history.add(command)
println()
}
}
- Output:
** Welcome to the Ranger readline interface **
** which performs operations on a range of integers **
Commands available:
range [i] [j], help, show, square, cube, add [n], sub [n]
mul [n], prev, hist, quit
help
range [i] [j] - sets the current range to [i, j] and shows them
- if i > j, sets the current range to the single value [i]
help - displays help for each command
show - displays a maximum of 10 values from the current range
square - sets the current range to their squares and shows them
cube - sets the current range to their cubes and shows them
add [i] - adds [i] to the current range and shows them
sub [i] - subtracts [i] from the current range and shows them
mul [i] - multiplies the current range by [i] and shows them
prev - displays previous command entered
hist - displays a maximum of last 10 commands entered, newest first
quit - quits Ranger
< items in square brackets denote integers to be supplied e.g. range 1 5 >
< right/left arrow keys can be used to scroll through previous commands >
range 1 3
1
2
3
add 1
2
3
4
mul 2
4
6
8
sub 3
1
3
5
square
1
9
25
cube
1
729
15625
hist
- cube
- square
- sub 3
- mul 2
- add 1
- range 1 3
- help
prev
- hist
show
1
729
15625
quit
Nim
Nim provides a module rdstdin to read form standard input file. This modules provides navigation in history of previous commands using the up and down keys.
import rdstdin, strutils, tables
var history: seq[string]
proc hello =
echo "Hello World!"
history.add "hello"
proc hist =
if history.len == 0:
echo "no history"
else:
for cmd in history:
echo " -", cmd
history.add "hist"
proc help =
echo "Available commands:"
echo " hello"
echo " hist"
echo " exit"
echo " help"
history.add "help"
const Vfs = {"help": help, "hist": hist, "hello": hello}.toTable
echo "Enter a command, type help for a listing."
while true:
let line = try:
readLineFromStdin(">").strip()
except IOError:
echo "EOF encountered. Bye."
break
if line == "exit": break
if line notin Vfs:
echo "Unknown command, try again."
else:
Vfs[line]()
- Output:
Sample session.
Enter a command, type help for a listing. >help Available commands: hello hist exit help >hello Hello World! >hist -help -hello >quit Unknown command, try again. >exit
PARI/GP
gp uses readline, but it can also be used directly in PARI:
#include <stdio.h>
#include <pari/pari.h>
#include <readline/readline.h>
#include <setjmp.h>
jmp_buf env;
void gp_err_recover(long numerr) { longjmp(env, numerr); }
/* History handling (%1, %2, etc.)*/
pari_stack s_history;
GEN *history;
GEN parihist(long p)
{
if (p > 0 && p<=s_history.n)
return history[p-1];
else if (p<=0 && s_history.n+p-1>=0)
return history[s_history.n+p-1];
pari_err(talker,"History result %ld not available [%%1-%%%ld]",p,s_history.n);
return NULL; /* not reached */
}
int main(int argc, char **argv)
{
char *in, *out;
GEN z;
entree hist={"%",0,(void*)parihist,13,"D0,L,","last history item."};
printf("Welcome to minigp!\n");
pari_init(8000000,500000);
cb_pari_err_recover = gp_err_recover;
pari_add_function(&hist);
stack_init(&s_history,sizeof(*history),(void**)&history);
(void)setjmp(env);
while(1)
{
in = readline("? ");
if (!in) break;
if (!*in) continue;
z = gp_read_str(in);
stack_pushp(&s_history,(void*)gclone(z)); /*Add to history */
out = GENtostr(z);
printf("%%%ld = %s\n",s_history.n,out);
free(in); free(out); avma=top;
}
return 0;
}
Code thanks to Bill Allombert
Perl
A Perl shell with command history, line-editing and variable-name completion. Simplified from the example supplied with the CPAN module Term::Readline::Gnu.
use strict;
use warnings;
use Term::ReadLine;
use POSIX;
my $term = Term::ReadLine->new( 'simple Perl shell' );
my $attribs = $term->Attribs;
$attribs->{completion_append_character} = ' ';
$attribs->{attempted_completion_function} = \&attempt_perl_completion;
$attribs->{completion_display_matches_hook} = \&perl_symbol_display_match_list;
while (defined(my $command = &reader)) {
my @result = eval ("package main; $command");
print "$_\n" for @result;
}
sub reader {
my $command = $term->readline('> ');
$term->addhistory($command) if $command;
$command;
}
sub perl_symbol_display_match_list {
my($matches, $num_matches, $max_length) = @_;
map { $_ =~ s/^((\$#|[\@\$%&])?).*::(.+)/$3/; }(@{$matches});
$term->display_match_list($matches);
$term->forced_update_display;
}
sub attempt_perl_completion {
my ($text, $line, $start, $end) = @_;
$term->completion_matches($text, \&perl_symbol_completion_function);
}
use vars qw($i @matches $prefix);
sub perl_symbol_completion_function {
my($text, $state) = @_;
my %type = ('$' => 'SCALAR', '*' => 'SCALAR', '@' => 'ARRAY', '$#' => 'ARRAY', '%' => 'HASH', '&' => 'CODE');
if ($state) {
$i++;
} else {
my ($pre, $pkg, $sym);
$i = 0;
no strict qw(refs);
($prefix, $pre, $pkg) = ($text =~ m/^((\$#|[\@\$%&])?(.*::)?)/);
@matches = grep /::$/, $pkg ? keys %$pkg : keys %::;
$pkg = '::' unless $pkg;
@matches = (@matches, grep (/^\w+$/ && ($sym = $pkg . $_, defined *$sym{$type{$pre}}), keys %$pkg));
}
my $entry;
for (; $i <= $#matches; $i++) {
$entry = $prefix . $matches[$i];
return $entry if ($entry =~ /^\Q$text/);
}
undef;
}
Phix
The phix interpreter has a readline interface, however the code involved is far too much to replicate here (see p.exw, processCommandLine() which opens p.ini and populates default_commandlines, then invokes gets0() from pgets0.ew with keyHandler() as a callback. Currently only tested/working on Windows, not linux.) There are no "application specific commands", however you could init default_commandlines with some.
While the lack of code may disappoint, I think this is a closer match to the task intention than most.
A snapshot of running the interpreter: first I pressed ?, then F7, then "ed": keying "e" did little, but "ed" auto-completed the "ix" part as that was then the only match.
Phix hybrid interpreter/compiler. Version 0.7.9 (32 bit Windows) Copyright Pete Lomax 2006..2016 Enter ? for options or filename to execute:? <snip> Press F7 to list prompt history, up/down to select. Enter ? for options or filename to execute: demo\pGUI\tee demo\edix\edix demo\win32demo\generic.exw t61 p7 demo\win32demo\generic -d! t01 -d! test/t01type.exw edix test\trace p64 -c p64 -cp -test -c -test -c e01 pgui -d e01 pdemo e01 use (pg) up/down to select:edix
Pike
watch.pike is the solution from Simple database#Pike. this solution demonstrates how to retrofit an application with a readline interface by inheriting the original and overriding specific functions.
#!/usr/bin/pike
inherit "watch.pike";
Stdio.Readline readln = Stdio.Readline();
void print_help()
{
write("The following commands are available: \n");
write(sort(indices(functions))*", ");
write("\n");
}
void watch_add()
{
::watch_add(db);
}
void watch_list()
{
::watch_list(db);
}
void do_exit()
{
exit(0);
}
mapping functions = ([ "add":watch_add,
"list":watch_list,
"load":watch_load,
"save":watch_save,
"help":print_help,
"quit":do_exit ]);
string prompt_read(string prompt)
{
return readln->read(prompt+": ");
}
void main()
{
Stdio.Readline.History readline_history = Stdio.Readline.History(512);
readln->enable_history(readline_history);
string prompt="> ";
print_help();
while(1)
{
string input=readln->read(prompt);
if(!input)
exit(0);
if(input != "")
{
if (functions[input])
functions[input]();
else
{
write("unknown command\n");
print_help();
}
}
}
}
Sample session:
pike watch_rl.pike The following commands are available: add, help, list, load, quit, save > load > list Rosetta Code 2 Simple Database (27.10.2011.) > add Series: Rdm asks! Title: Balanced ternary Episode: 1 Date watched: 1.11.2011 Add new series? [y/n]: : y > list Rdm asks! 1 Balanced ternary (1.11.2011.) Rosetta Code 2 Simple Database (27.10.2011.) > hello unknown command The following commands are available: add, help, list, load, quit, save > save > quit
Python
Python readline interface is enabled by default in the interpreter REPL, and can be enabled in user code simply by importing the readline module
#!/usr/bin/env python3
#
# A simple readline demo that does nothing.
# Interactive line editing and history active
#
import readline
while True:
try:
print(input('> '))
except:
break
Racket
Racket's has a readline interface which is not used by default due to its license. This includes the usual readline-style editing, and tab-completion for Racket bindings. It is possible to use it as a library, or as a REPL convenience (both uses described in the documentation) -- but it is better to use xrepl which provides an enhanced command-line REPL and includes the readline interaction.
Raku
(formerly Perl 6)
Raku has a built in REPL that can be initiated by running the Raku executable without any parameters. It is fairly basic on its own but here are bindings available in the Raku ecosystem for GNU Readline and/or Linenoise either of which will automatically provide command history, tab completion and more advance command line editing capability if installed. They are not included in the Raku distribution directly. There are incompatible licensing requirements and providing hooks for third party tools allows for more customization options.
Linenoise is generally the preferred option unless you really want the emacs compatible command line editing key bindings. Readline is arguably more powerful but is somewhat fiddly to set up.
If you are not inclined to install Readline or Linenoise, the REPL also works fairly well with 3rd party tools like rlwrap.
REXX
This REXX programs supports a REDO (re-do) with very limited editing to keep the program simple.
It has a history (which can be interrogated) and some of the simple (MS) DOS commands.
The HELP (or ?), REDO, error checking, and abbreviations took up most of the program.
"User" commands (subroutines) are identified with a leading period (.) to make it easier to understand what's what.
/*REXX program implements a simple "readline" shell (modeled after a DOS shell). */
trace off /*suppress echoing of non-zero retCodes*/
signal on syntax; signal on noValue /*handle REXX program errors. */
cmdX='ATTRIB CAL CHDIR COPY DEL DIR ECHO EDIT FC FIND KEDIT LLL MEM MKDIR MORE REM REXX',
'RMDIR SET TYPE VER XCOPY' /* ◄──── the legal/known commands. */
cls= 'CLS' /*define the program to clear screen. */
@hist.= '*** command not defined. ***' /*initialize the history database. */
hist#=0 /*the number of commands in the history*/
prompt='Enter command ──or── ? ──or── Quit' /*the default PROMPT message text. */
sw=linesize() /*some REXX don't have this BIF. */
cls /*start with a clean slate (terminal). */
redoing=0 /*flag for executing naked ReDO cmd. */
/* [↓] do it 'til the fat lady sings. */
do forever; if prompter() then iterate /*Nothing entered? Then go try again. */
select /* [↓] now then, let's rock n' roll. */
when wordpos(xxxF,cmdX)\==0 then call .cmdX
when xxxF=='EXIT' | xxxF="QUIT" then leave /*da fat lady is done singing*/
when xxxF=='HISTORY' then call .history
when xxxF=='HELP' then call .help
when xxxF=='PROMPT' then call .prompt
when xxxF=='REDO' then call .redo
otherwise call er 'unknown command:' xxx yyy
end /*select*/
end /*forever*/
say xxxF'ting···' /*say goodbye, 'cause it's polite to do*/
exit /*stick a fork in it, we're all done. */
/*──────────────────────────────────────────────────────────────────────────────────────*/
er: say; say; say '****error****'; say; say arg(1); say; say; return
.prompt: if yyyU\=='' then prompt=yyy; return
.cmdX: xxxF yyy; return
/*──────────────────────────────────────────────────────────────────────────────────────*/
err: say; say; say center(' error! ', max(40, linesize()%2), "*"); say
do j=1 for arg(); say arg(j); say; end; say; exit 13
/*──────────────────────────────────────────────────────────────────────────────────────*/
noValue: syntax: call err 'REXX program' condition('C') "error",,
condition('D'),'REXX source statement (line' sigl"):",sourceline(sigl)
/*──────────────────────────────────────────────────────────────────────────────────────*/
.help: cmdsH= 'ATTRIB CHDIR CLS COPY DEL DIR ECHO EDIT FC FIND MEM MKDIR MORE PRINT',
'REM RMDIR SET TREE TYPE VER XCOPY' /*these have their own help via /? */
cmds= '?|Help|MANual ATTRIButes CALendar CD|CHDIR|CHANGEDir COPY DELete|ERASE',
'DELete|ERASE DIR ECHO EDIT FC|FILECOMPAre FIND HISTory Kedit LLL',
'MEM MD|MKDIR|MAKEDir MORE PRINT PROMPT Quit|EXIT',
'R4 RD|RMDIR|REMOVEDir REGINA REMark Rexx REDO SET TREE Type VER'
say center(strip(xxx yyy),sw-1,'═'); cmds_=cmds; yyyF=unabbrev(yyy)
help. = 'No help is available for the' yyy "command."
help.cal = 'shows a calendar for the current month or specified month.'
help.kedit = 'KEDITs the file specified.'
help.lll = 'shows a formatted listing of files in the current directory.'
help.prompt= 'sets the PROMPT message to the specified text.'
help.quit = 'quits (exits) this program.'
help.redo = 're-does the command # specified (or the last command).'
help.rexx = 'executes the REXX program specified.'
if yyy=='' then do j=1 while cmds_\==''
parse var cmds_ x cmds_
say left('',sw%2) changestr('|',x," | ")
end /*j*/
else select
when wordpos(yyyF,cmdsH)\==0 then yyyF '/?'
otherwise cmd?=yyyF
if left(help.yyyF,1)\==' ' then say yyyF ' ' help.yyyF
else say help.yyyF
end /*select*/
return
/*──────────────────────────────────────────────────────────────────────────────────────*/
.history: say center('history', sw-1, '═'); w=length(hist#)
do j=1 for hist#; say right(j,w) '═══►' @hist.j; end /*j*/
return
/*──────────────────────────────────────────────────────────────────────────────────────*/
prompter: if redoing then do; redoing=0; z=hist#-1 /*special case, bare REDO. */
parse var @hist.z xxx yyy
end
else do; if prompt\=='' then do; say; say prompt; end
parse pull xxx yyy
end
xxxU=xxx; upper xxxU; if xxx=='' then return 1 /*No input? Then try again*/
yyyU=yyy; upper yyyU; yyyU=strip(yyyU)
hist#=hist#+1; /*bump the history counter.*/
@hist.hist#=strip(xxx yyy) /*assign to history. */
xxxF=unAbbrev(xxx) /*maybe expand abbreviation*/
return 0
/*──────────────────────────────────────────────────────────────────────────────────────*/
.redo: select
when yyyU=='' then redoing=1 /*assume they want the last cmd. */
when words(yyy)\==1 then call er 'too many args specified for' xxx
when \datatype(yyy,'W') then call er "2nd arg isn't numeric for" xxx
otherwise nop
end /*select*/
if redoing then return /*handle with kid gloves. */
yyy=yyy/1 /*normalize it: +7 7. 1e1 007 7.0*/
say 'Re-doing:' @hist.yyy
@hist.yyy
return
/*──────────────────────────────────────────────────────────────────────────────────────*/
unabbrev: procedure; arg ccc
select
when abbrev('ATTRIBUTES' , ccc, 6) then return 'ATTRIB'
when abbrev('CALENDAR' , ccc, 3) then return 'CAL'
when abbrev('CHANGEDIR' , ccc, 7) |,
ccc=='CHDIR' |,
ccc=='CD' then return 'CHDIR'
when abbrev('CLEARSCREEN', ccc, 5) then return 'CLS'
when abbrev('FILECOMPARE', ccc, 9) then return 'FC'
when abbrev('DELETE' , ccc, 3) |,
ccc=='ERASE' then return 'DEL'
when abbrev('HISTORY' , ccc, 4) then return 'HISTORY'
when abbrev('HELP' , ccc, 1) |,
abbrev('MANUAL' , ccc, 3) |,
ccc=='?' then return 'HELP'
when abbrev('MAKEDIR' , ccc, 5) |,
ccc=='MKDIR' |,
ccc=='MD' then return 'MKDIR'
when abbrev('KEDIT' , ccc, 1) then return 'KEDIT'
when abbrev('QUIT' , ccc, 1) then return 'QUIT'
when abbrev('REMARK' , ccc, 3) then return 'REM'
when abbrev('REMOVEDIR' , ccc, 7) |,
ccc=='RMDIR' |,
ccc=='RD' then return 'RMDIR'
when abbrev('REXX' , ccc, 1) then return 'REXX'
when abbrev('TYPE' , ccc, 1) then return 'TYPE'
otherwise nop
end /*select*/
return ccc
This REXX program makes use of LINESIZE REXX program (or BIF) which is used to determine the screen width (or linesize) of the terminal (console).
The LINESIZE.REX REXX program is included here ──► LINESIZE.REX.
Some older REXXes don't have a changestr BIF, so one is included here ──► CHANGESTR.REX.
output showing a sample session:
Enter command ──or── ? ──or── Quit
hel
═══════════════════════════════════════════hel══════════════════════════════════
? | Help | MANual
ATTRIButes
CALendar
CD | CHDIR | CHANGEDir
COPY
DELete | ERASE
DELete | ERASE
DIR
ECHO
EDIT
FC | FILECOMPAre
FIND
HISTory
Kedit
LLL
MEM
MD | MKDIR | MAKEDir
MORE
PRINT
PROMPT
Quit | EXIT
R4
RD | RMDIR | REMOVEDir
REGINA
REMark
Rexx
REDO
SET
TREE
Type
VER
Enter command ──or── ? ──or── Quit
rexx $mayan 123,456,787,654,321
╔════╗ ╔════╗ ╔════╗ ╔════╗ ╔════╗ ╔════╗ ╔════╗ ╔════╗ ╔════╗ ╔════╗ ╔════╗
║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ∙ ║ ║ ║ ║ ∙ ║ ║ ║
║ ∙∙ ║ ║ ║ ║ ║ ║ ║ ║ ∙∙ ║ ║ ║ ║ ║ ║────║ ║────║ ║────║ ║ ║
║────║ ║ ║ ║ ║ ║────║ ║────║ ║ ∙ ║ ║ ║ ║────║ ║────║ ║────║ ║ ║
║────║ ║ ∙ ║ ║ ∙∙ ║ ║────║ ║────║ ║────║ ║ ∙∙ ║ ║────║ ║────║ ║────║ ║ ∙ ║
╚════╝ ╚════╝ ╚════╝ ╚════╝ ╚════╝ ╚════╝ ╚════╝ ╚════╝ ╚════╝ ╚════╝ ╚════╝
Enter command ──or── ? ──or── Quit
cal
┌────────────────────────────────────────────────────────────────────────────┐
│ │
│ │
│ June 2012 │
│ │
│ │
│ Sunday Monday Tuesday Wednesday Thursday Friday Saturday │
├──────────┬──────────┬──────────┬──────────┬──────────┬──────────┬──────────┤
│ │ │ │ │ │ │ │
│ │ │ │ │ │ │ │
│ │ │ │ │ │ ─ 1 ─ │ 2 │
│ │ │ │ │ │ │ │
│ │ │ │ │ │ │ │
├──────────┼──────────┼──────────┼──────────┼──────────┼──────────┼──────────┤
│ │ │ │ │ │ │ │
│ │ │ │ │ │ │ │
│ 3 │ 4 │ 5 │ 6 │ 7 │ 8 │ 9 │
│ │ │ │ │ │ │ │
│ │ │ │ │ │ │ │
├──────────┼──────────┼──────────┼──────────┼──────────┼──────────┼──────────┤
│ │ │ │ │ │ │ │
│ │ │ │ │ │ │ │
│ 10 │ 11 │ 12 │ 13 │ 14 │ 15 │ 16 │
│ │ │ │ │ │ │ │
│ │ │ │ │ │ │ │
├──────────┼──────────┼──────────┼──────────┼──────────┼──────────┼──────────┤
│ │ │ │ │ │ │ │
│ │ │ │ │ │ │ │
│ 17 │ 18 │ 19 │ 20 │ 21 │ 22 │ 23 │
│ │ │ │ │ │ │ │
│ │ │ │ │ │ │ │
├──────────┼──────────┼──────────┼──────────┼──────────┼──────────┼──────────┤
│ │ │ │ │ │ │ │
│ │ │ │ │ │ │ │
│ 24 │ 25 │ 26 │ 27 │ 28 │ 29 │ 30 │
│ │ │ │ │ │ │ │
│ │ │ │ │ │ │ │
└──────────┴──────────┴──────────┴──────────┴──────────┴──────────┴──────────┘
Enter command ──or── ? ──or── Quit
LLL
mm/dd/yyyy hh:mm ──filesize── ─────────────────filename D:\*.*─────────────────
06/01/2012 10:36 2,322 DIV_GRID.TXT
05/13/2012 20:39 1,044 MOD_EXP.REX
05/13/2012 19:39 694 MOD_EXP.TXT
06/01/2012 02:32 1,439 RCOMBN.RX_
06/01/2012 02:24 7,181 READLINT.REX
05/29/2012 22:48 60 sub00.REX
──────────────────────12,740 <──────────────total bytes [6 files]
Enter command ──or── ? ──or── Quit
dir
Volume in drive D is -----D-----
Volume Serial Number is 68D0-6356
Directory of D:\
05/09/2012 12:40 <DIR> Config.Msi
12/16/2005 19:54 <DIR> Documents and Settings
01/15/2006 10:33 <DIR> Program Files
04/14/2010 19:58 <DIR> Recycled
12/16/2005 20:29 <DIR> System Volume Information
01/26/2011 00:21 <DIR> temp
12/16/2005 19:42 <DIR> WINDOWS
01/06/2006 14:43 211 boot.ini
06/01/2012 10:36 2,322 DIV_GRID.TXT
12/16/2005 20:18 0 IO.SYS
05/13/2012 20:39 1,044 MOD_EXP.REX
05/13/2012 19:39 694 MOD_EXP.TXT
12/16/2005 20:18 0 MSDOS.SYS
08/04/2004 12:00 47,564 NTDETECT.COM
08/04/2004 12:00 250,032 ntldr
06/01/2012 02:32 1,439 RCOMBN.RX_
06/01/2012 02:24 7,181 READLINT.REX
05/29/2012 22:48 60 sub00.REX
11 File(s) 310,547 bytes
7 Dir(s) 6,793,314,304 bytes free
Enter command ──or── ? ──or── Quit
help ver
════════════════════════════════════════help ver═════════════════════════════════════════
Displays the Windows XP version.
VER
Enter command ──or── ? ──or── Quit
ver
Microsoft Windows XP [Version 5.1.2600]
Enter command ──or── ? ──or── Quit
q
QUITting...
Ruby
This application provides auto-completion for these commands: search download open help history quit url prev past.
Auto-completion is applied by pressing the tab-key.
A history of the commands is navigated by the up- and down-keys. All commands are just echoed, except "quit" which exits.
It uses the Ruby 2.3 method Hash#to_proc.
require "readline"
require "abbrev"
commands = %w[search download open help history quit url prev past]
Readline.completion_proc = commands.abbrev.to_proc
while buf = Readline.readline(">", true) # true means: keep history.
exit if buf.strip == "quit"
p buf
end
Sidef
require('Term::ReadLine')
var term = %O<Term::ReadLine>.new('Example')
term.addhistory('foo')
term.addhistory('bar')
loop {
var cmd = term.readline("Prompt: ") \\ break
if (cmd ~~ %w[q quit]) {
break
}
say "You inserted <<#{cmd}>>"
}
Wren
import "io" for Stdin, Stdout
class ReadLine {
static start {
__hist = []
System.print("Enter a command, type help for a listing.")
while (true) {
System.write(">")
Stdout.flush()
var cmd = Stdin.readLine().trim()
if (cmd == "exit") {
return
} else if (cmd == "hello") {
hello_
} else if (cmd == "hist") {
hist_
} else if (cmd == "help") {
help_
} else {
System.print("Unknown command, try again")
}
}
}
static hello_ {
System.print("Hello World!")
__hist.add("hello")
}
static hist_ {
if (__hist.count == 0) {
System.print("No history")
} else {
for (cmd in __hist) System.print(" - %(cmd)")
}
__hist.add("hist")
}
static help_ {
System.print("Available commands:")
System.print(" hello")
System.print(" hist")
System.print(" exit")
System.print(" help")
__hist.add("help")
}
}
ReadLine.start
- Output:
Sample session (as Go):
Enter a command, type help for a listing. >hit Unknown command, try again >hist No history >help Available commands: hello hist exit help >hello Hello World! >hist - hist - help - hello >exit