perl 5.002beta2 patch: lib/Term/ReadLine.pm

Stub new file to interface to various readline packages, or
give stub functions if none are found.

diff --git a/lib/Term/ReadLine.pm b/lib/Term/ReadLine.pm
new file mode 100644 (file)
index 0000000..5104426
--- /dev/null
+++ b/lib/Term/ReadLine.pm
@@ -0,0 +1,182 @@
+=head1 NAME
+
+C<Term::ReadLine>: Perl interface to various C<readline> packages. If
+no real package is found, substitutes stubs instead of basic functions.
+
+=head1 SYNOPSIS
+
+  use Term::ReadLine;
+  $term = new Term::ReadLine 'Simple Perl calc';
+  $prompt = "Enter your arithmetic expression: ";
+  $OUT = $term->OUT || STDOUT;
+  while ( defined ($_ = $term->readline($prompt)) ) {
+    $res = eval($_), "\n";
+    warn $@ if $@;
+    print $OUT $res, "\n" unless $@;
+    $term->addhistory($_) if /\S/;
+  }
+
+=head1 Minimal set of supported functions
+
+All the supported functions should be called as methods, i.e., either as 
+
+  $term = new Term::ReadLine 'name';
+
+or as 
+
+  $term->addhistory('row');
+
+where $term is a return value of Term::ReadLine->Init.
+
+=over 12
+
+=item C<ReadLine>
+
+returns the actual package that executes the commands. Among possible
+values are C<Term::ReadLine::Gnu>, C<Term::ReadLine::Perl>,
+C<Term::ReadLine::Stub Exporter>.
+
+=item C<new>
+
+returns the handle for subsequent calls to following
+functions. Argument is the name of the application. Optionally can be
+followed by two arguments for C<IN> and C<OUT> filehandles. These
+arguments should be globs.
+
+=item C<readline>
+
+gets an input line, I<possibly> with actual C<readline>
+support. Trailing newline is removed. Returns C<undef> on C<EOF>.
+
+=item C<addhistory>
+
+adds the line to the history of input, from where it can be used if
+the actual C<readline> is present.
+
+=item C<IN>, $C<OUT>
+
+return the filehandles for input and output or C<undef> if C<readline>
+input and output cannot be used for Perl.
+
+=item C<MinLine>
+
+If argument is specified, it is an advice on minimal size of line to
+be included into history.  C<undef> means do not include anything into
+history. Returns the old value.
+
+=item C<findConsole>
+
+returns an array with two strings that give most appropriate names for
+files for input and output using conventions C<"<$in">, C<"E<gt>out">.
+
+=item C<Features>
+
+Returns a reference to a hash with keys being features present in
+current implementation. Several optional features are used in the
+minimal interface: C<appname> should be present if the first argument
+to C<new> is recognized, and C<minline> should be present if
+C<MinLine> method is not dummy.  C<autohistory> should be present if
+lines are put into history automatically (maybe subject to
+C<MinLine>), and C<addhistory> if C<addhistory> method is not dummy.
+
+=back
+
+Actually C<Term::ReadLine> can use some other package, that will
+support reacher set of commands.
+
+=head1 EXPORTS
+
+None
+
+=cut
+
+package Term::ReadLine::Stub;
+
+$DB::emacs = $DB::emacs;       # To peacify -w
+
+sub ReadLine {'Term::ReadLine::Stub'}
+sub readline {
+  my ($in,$out,$str) = @{shift()};
+  print $out shift; 
+  $str = scalar <$in>;
+  # bug in 5.000: chomping empty string creats length -1:
+  chomp $str if defined $str;
+  $str;
+}
+sub addhistory {}
+
+sub findConsole {
+    my $console;
+
+    if (-e "/dev/tty") {
+       $console = "/dev/tty";
+    } elsif (-e "con") {
+       $console = "con";
+    } else {
+       $console = "sys\$command";
+    }
+
+    if (defined $ENV{'OS2_SHELL'}) { # In OS/2
+      if ($DB::emacs) {
+       $console = undef;
+      } else {
+       $console = "/dev/con";
+      }
+    }
+
+    $consoleOUT = $console;
+    $console = "&STDIN" unless defined $console;
+    if (!defined $consoleOUT) {
+      $consoleOUT = defined fileno(STDERR) ? "&STDERR" : "&STDOUT";
+    }
+    ($console,$consoleOUT);
+}
+
+sub new {
+  die "method new called with wrong number of arguments" 
+    unless @_==2 or @_==4;
+  #local (*FIN, *FOUT);
+  my ($FIN, $FOUT);
+  if (@_==2) {
+    ($console, $consoleOUT) = findConsole;
+
+    open(FIN, "<$console"); 
+    open(FOUT,">$consoleOUT");
+    #OUT->autoflush(1);                # Conflicts with debugger?
+    $sel = select(FOUT);
+    $| = 1;                            # for DB::OUT
+    select($sel);
+    bless [\*FIN, \*FOUT];
+  } else {                     # Filehandles supplied
+    $FIN = $_[2]; $FOUT = $_[3];
+    #OUT->autoflush(1);                # Conflicts with debugger?
+    $sel = select($FOUT);
+    $| = 1;                            # for DB::OUT
+    select($sel);
+    bless [$FIN, $FOUT];
+  }
+}
+sub IN { shift->[0] }
+sub OUT { shift->[1] }
+sub MinLine { undef }
+sub Features { {} }
+
+package Term::ReadLine;                # So late to allow the above code be defined?
+eval "use Term::ReadLine::Gnu;" or eval "use Term::ReadLine::Perl;";
+
+#require FileHandle;
+
+# To make possible switch off RL in debugger: (Not needed, work done
+# in debugger).
+
+if (defined &Term::ReadLine::Gnu::readline) {
+  @ISA = qw(Term::ReadLine::Gnu Term::ReadLine::Stub);
+} elsif (defined &Term::ReadLine::Perl::readline) {
+  @ISA = qw(Term::ReadLine::Perl Term::ReadLine::Stub);
+} else {
+  @ISA = qw(Term::ReadLine::Stub);
+}
+
+
+1;
+