lib/perl5/5.6.1/Term/ReadLine.pm

   1 =head1 NAME
   2
   3 Term::ReadLine - Perl interface to various C<readline> packages. If
   4 no real package is found, substitutes stubs instead of basic functions.
   5
   6 =head1 SYNOPSIS
   7
   8   use Term::ReadLine;
   9   $term = new Term::ReadLine 'Simple Perl calc';
  10   $prompt = "Enter your arithmetic expression: ";
  11   $OUT = $term->OUT || STDOUT;
  12   while ( defined ($_ = $term->readline($prompt)) ) {
  13     $res = eval($_), "\n";
  14     warn $@ if $@;
  15     print $OUT $res, "\n" unless $@;
  16     $term->addhistory($_) if /\S/;
  17   }
  18
  19 =head1 DESCRIPTION
  20
  21 This package is just a front end to some other packages. At the moment
  22 this description is written, the only such package is Term-ReadLine,
  23 available on CPAN near you. The real target of this stub package is to
  24 set up a common interface to whatever Readline emerges with time.
  25
  26 =head1 Minimal set of supported functions
  27
  28 All the supported functions should be called as methods, i.e., either as
  29
  30   $term = new Term::ReadLine 'name';
  31
  32 or as
  33
  34   $term->addhistory('row');
  35
  36 where $term is a return value of Term::ReadLine-E<gt>Init.
  37
  38 =over 12
  39
  40 =item C<ReadLine>
  41
  42 returns the actual package that executes the commands. Among possible
  43 values are C<Term::ReadLine::Gnu>, C<Term::ReadLine::Perl>,
  44 C<Term::ReadLine::Stub Exporter>.
  45
  46 =item C<new>
  47
  48 returns the handle for subsequent calls to following
  49 functions. Argument is the name of the application. Optionally can be
  50 followed by two arguments for C<IN> and C<OUT> filehandles. These
  51 arguments should be globs.
  52
  53 =item C<readline>
  54
  55 gets an input line, I<possibly> with actual C<readline>
  56 support. Trailing newline is removed. Returns C<undef> on C<EOF>.
  57
  58 =item C<addhistory>
  59
  60 adds the line to the history of input, from where it can be used if
  61 the actual C<readline> is present.
  62
  63 =item C<IN>, $C<OUT>
  64
  65 return the filehandles for input and output or C<undef> if C<readline>
  66 input and output cannot be used for Perl.
  67
  68 =item C<MinLine>
  69
  70 If argument is specified, it is an advice on minimal size of line to
  71 be included into history.  C<undef> means do not include anything into
  72 history. Returns the old value.
  73
  74 =item C<findConsole>
  75
  76 returns an array with two strings that give most appropriate names for
  77 files for input and output using conventions C<"E<lt>$in">, C<"E<gt>out">.
  78
  79 =item Attribs
  80
  81 returns a reference to a hash which describes internal configuration
  82 of the package. Names of keys in this hash conform to standard
  83 conventions with the leading C<rl_> stripped.
  84
  85 =item C<Features>
  86
  87 Returns a reference to a hash with keys being features present in
  88 current implementation. Several optional features are used in the
  89 minimal interface: C<appname> should be present if the first argument
  90 to C<new> is recognized, and C<minline> should be present if
  91 C<MinLine> method is not dummy.  C<autohistory> should be present if
  92 lines are put into history automatically (maybe subject to
  93 C<MinLine>), and C<addhistory> if C<addhistory> method is not dummy.
  94
  95 If C<Features> method reports a feature C<attribs> as present, the
  96 method C<Attribs> is not dummy.
  97
  98 =back
  99
 100 =head1 Additional supported functions
 101
 102 Actually C<Term::ReadLine> can use some other package, that will
 103 support reacher set of commands.
 104
 105 All these commands are callable via method interface and have names
 106 which conform to standard conventions with the leading C<rl_> stripped.
 107
 108 The stub package included with the perl distribution allows some
 109 additional methods:
 110
 111 =over 12
 112
 113 =item C<tkRunning>
 114
 115 makes Tk event loop run when waiting for user input (i.e., during
 116 C<readline> method).
 117
 118 =item C<ornaments>
 119
 120 makes the command line stand out by using termcap data.  The argument
 121 to C<ornaments> should be 0, 1, or a string of a form
 122 C<"aa,bb,cc,dd">.  Four components of this string should be names of
 123 I<terminal capacities>, first two will be issued to make the prompt
 124 standout, last two to make the input line standout.
 125
 126 =item C<newTTY>
 127
 128 takes two arguments which are input filehandle and output filehandle.
 129 Switches to use these filehandles.
 130
 131 =back
 132
 133 One can check whether the currently loaded ReadLine package supports
 134 these methods by checking for corresponding C<Features>.
 135
 136 =head1 EXPORTS
 137
 138 None
 139
 140 =head1 ENVIRONMENT
 141
 142 The environment variable C<PERL_RL> governs which ReadLine clone is
 143 loaded. If the value is false, a dummy interface is used. If the value
 144 is true, it should be tail of the name of the package to use, such as
 145 C<Perl> or C<Gnu>.
 146
 147 As a special case, if the value of this variable is space-separated,
 148 the tail might be used to disable the ornaments by setting the tail to
 149 be C<o=0> or C<ornaments=0>.  The head should be as described above, say
 150
 151 If the variable is not set, or if the head of space-separated list is
 152 empty, the best available package is loaded.
 153
 154   export "PERL_RL=Perl o=0"     # Use Perl ReadLine without ornaments
 155   export "PERL_RL= o=0"         # Use best available ReadLine without ornaments
 156
 157 (Note that processing of C<PERL_RL> for ornaments is in the discretion of the
 158 particular used C<Term::ReadLine::*> package).
 159
 160 =cut
 161
 162 package Term::ReadLine::Stub;
 163 @ISA = qw'Term::ReadLine::Tk Term::ReadLine::TermCap';
 164
 165 $DB::emacs = $DB::emacs;        # To peacify -w
 166 *rl_term_set = \@Term::ReadLine::TermCap::rl_term_set;
 167
 168 sub ReadLine {'Term::ReadLine::Stub'}
 169 sub readline {
 170   my $self = shift;
 171   my ($in,$out,$str) = @$self;
 172   my $prompt = shift;
 173   print $out $rl_term_set[0], $prompt, $rl_term_set[1], $rl_term_set[2];
 174   $self->register_Tk
 175      if not $Term::ReadLine::registered and $Term::ReadLine::toloop
 176         and defined &Tk::DoOneEvent;
 177   #$str = scalar <$in>;
 178   $str = $self->get_line;
 179   $str =~ s/^\s*\Q$prompt\E// if ($^O eq 'MacOS');
 180   print $out $rl_term_set[3];
 181   # bug in 5.000: chomping empty string creats length -1:
 182   chomp $str if defined $str;
 183   $str;
 184 }
 185 sub addhistory {}
 186
 187 sub findConsole {
 188     my $console;
 189
 190     if ($^O eq 'MacOS') {
 191         $console = "Dev:Console";
 192     } elsif (-e "/dev/tty") {
 193         $console = "/dev/tty";
 194     } elsif (-e "con" or $^O eq 'MSWin32') {
 195         $console = "con";
 196     } else {
 197         $console = "sys\$command";
 198     }
 199
 200     if (($^O eq 'amigaos') || ($^O eq 'beos') || ($^O eq 'epoc')) {
 201         $console = undef;
 202     }
 203     elsif ($^O eq 'os2') {
 204       if ($DB::emacs) {
 205         $console = undef;
 206       } else {
 207         $console = "/dev/con";
 208       }
 209     }
 210
 211     $consoleOUT = $console;
 212     $console = "&STDIN" unless defined $console;
 213     if (!defined $consoleOUT) {
 214       $consoleOUT = defined fileno(STDERR) ? "&STDERR" : "&STDOUT";
 215     }
 216     ($console,$consoleOUT);
 217 }
 218
 219 sub new {
 220   die "method new called with wrong number of arguments"
 221     unless @_==2 or @_==4;
 222   #local (*FIN, *FOUT);
 223   my ($FIN, $FOUT, $ret);
 224   if (@_==2) {
 225     ($console, $consoleOUT) = findConsole;
 226
 227     open(FIN, "<$console");
 228     open(FOUT,">$consoleOUT");
 229     #OUT->autoflush(1);         # Conflicts with debugger?
 230     $sel = select(FOUT);
 231     $| = 1;                             # for DB::OUT
 232     select($sel);
 233     $ret = bless [\*FIN, \*FOUT];
 234   } else {                      # Filehandles supplied
 235     $FIN = $_[2]; $FOUT = $_[3];
 236     #OUT->autoflush(1);         # Conflicts with debugger?
 237     $sel = select($FOUT);
 238     $| = 1;                             # for DB::OUT
 239     select($sel);
 240     $ret = bless [$FIN, $FOUT];
 241   }
 242   if ($ret->Features->{ornaments}
 243       and not ($ENV{PERL_RL} and $ENV{PERL_RL} =~ /\bo\w*=0/)) {
 244     local $Term::ReadLine::termcap_nowarn = 1;
 245     $ret->ornaments(1);
 246   }
 247   return $ret;
 248 }
 249
 250 sub newTTY {
 251   my ($self, $in, $out) = @_;
 252   $self->[0] = $in;
 253   $self->[1] = $out;
 254   my $sel = select($out);
 255   $| = 1;                               # for DB::OUT
 256   select($sel);
 257 }
 258
 259 sub IN { shift->[0] }
 260 sub OUT { shift->[1] }
 261 sub MinLine { undef }
 262 sub Attribs { {} }
 263
 264 my %features = (tkRunning => 1, ornaments => 1, 'newTTY' => 1);
 265 sub Features { \%features }
 266
 267 package Term::ReadLine;         # So late to allow the above code be defined?
 268
 269 my ($which) = exists $ENV{PERL_RL} ? split /\s+/, $ENV{PERL_RL} : undef;
 270 if ($which) {
 271   if ($which =~ /\bgnu\b/i){
 272     eval "use Term::ReadLine::Gnu;";
 273   } elsif ($which =~ /\bperl\b/i) {
 274     eval "use Term::ReadLine::Perl;";
 275   } else {
 276     eval "use Term::ReadLine::$which;";
 277   }
 278 } elsif (defined $which and $which ne '') {     # Defined but false
 279   # Do nothing fancy
 280 } else {
 281   eval "use Term::ReadLine::Gnu; 1" or eval "use Term::ReadLine::Perl; 1";
 282 }
 283
 284 #require FileHandle;
 285
 286 # To make possible switch off RL in debugger: (Not needed, work done
 287 # in debugger).
 288
 289 if (defined &Term::ReadLine::Gnu::readline) {
 290   @ISA = qw(Term::ReadLine::Gnu Term::ReadLine::Stub);
 291 } elsif (defined &Term::ReadLine::Perl::readline) {
 292   @ISA = qw(Term::ReadLine::Perl Term::ReadLine::Stub);
 293 } else {
 294   @ISA = qw(Term::ReadLine::Stub);
 295 }
 296
 297 package Term::ReadLine::TermCap;
 298
 299 # Prompt-start, prompt-end, command-line-start, command-line-end
 300 #     -- zero-width beautifies to emit around prompt and the command line.
 301 @rl_term_set = ("","","","");
 302 # string encoded:
 303 $rl_term_set = ',,,';
 304
 305 sub LoadTermCap {
 306   return if defined $terminal;
 307
 308   require Term::Cap;
 309   $terminal = Tgetent Term::Cap ({OSPEED => 9600}); # Avoid warning.
 310 }
 311
 312 sub ornaments {
 313   shift;
 314   return $rl_term_set unless @_;
 315   $rl_term_set = shift;
 316   $rl_term_set ||= ',,,';
 317   $rl_term_set = 'us,ue,md,me' if $rl_term_set eq '1';
 318   my @ts = split /,/, $rl_term_set, 4;
 319   eval { LoadTermCap };
 320   unless (defined $terminal) {
 321     warn("Cannot find termcap: $@\n") unless $Term::ReadLine::termcap_nowarn;
 322     $rl_term_set = ',,,';
 323     return;
 324   }
 325   @rl_term_set = map {$_ ? $terminal->Tputs($_,1) || '' : ''} @ts;
 326   return $rl_term_set;
 327 }
 328
 329
 330 package Term::ReadLine::Tk;
 331
 332 $count_handle = $count_DoOne = $count_loop = 0;
 333
 334 sub handle {$giveup = 1; $count_handle++}
 335
 336 sub Tk_loop {
 337   # Tk->tkwait('variable',\$giveup);    # needs Widget
 338   $count_DoOne++, Tk::DoOneEvent(0) until $giveup;
 339   $count_loop++;
 340   $giveup = 0;
 341 }
 342
 343 sub register_Tk {
 344   my $self = shift;
 345   $Term::ReadLine::registered++
 346     or Tk->fileevent($self->IN,'readable',\&handle);
 347 }
 348
 349 sub tkRunning {
 350   $Term::ReadLine::toloop = $_[1] if @_ > 1;
 351   $Term::ReadLine::toloop;
 352 }
 353
 354 sub get_c {
 355   my $self = shift;
 356   $self->Tk_loop if $Term::ReadLine::toloop && defined &Tk::DoOneEvent;
 357   return getc $self->IN;
 358 }
 359
 360 sub get_line {
 361   my $self = shift;
 362   $self->Tk_loop if $Term::ReadLine::toloop && defined &Tk::DoOneEvent;
 363   my $in = $self->IN;
 364   local ($/) = "\n";
 365   return scalar <$in>;
 366 }
 367
 368 1;
 369