hooks up two processes, 2nd of which has one line of output per line of input, expected by the first, which starts off the communication

git-svn-id: https://ws10smt.googlecode.com/svn/trunk@281 ec762483-ff6d-05da-a07a-a48fb63a330f

1 files changed, 35 insertions, 0 deletions

diff --git a/vest/line_mediator.pl b/vest/line_mediator.pl
new file mode 100755
index 00000000..defc11e8
--- /dev/null
+++ b/vest/line_mediator.pl
@@ -0,0 +1,35 @@
+#!/usr/bin/perl -w
+#hooks up two processes, 2nd of which has one line of output per line of input, expected by the first, which starts off the communication
+
+# if you don't know how to fork/exec in a C program, this could be helpful under limited cirmustances (would be ok to liaise with sentserver)
+
+use strict;
+use IPC::Open2;
+$,=' ';
+my $quiet=$ENV{QUIET};
+sub info {
+    print STDERR @_ unless $quiet;
+}
+
+my @c1;
+do {
+    push @c1,shift
+} while $c1[$#c1] ne '--';
+pop @c1;
+my @c2=@ARGV;
+(scalar @c1 && scalar @c2) || die "usage: $0 cmd1 args -- cmd2 args; hooks up two processes, 2nd of which has one line of output per line of input, expected by the first, which starts off the communication.  crosses stdin/stderr of cmd1 and cmd2 line by line (both must flush on newline and output.  cmd1 initiates the conversation (sends the first line).  QUIET env var suppresses debugging output.";
+info("1 cmd:",@c1,"\n");
+info("2 cmd:",@c2,"\n");
+my ($R1,$W1,$R2,$W2);
+my $c1p=open2($R1,$W1,@c1); # Open2 R W backward from Open3.
+my $c2p=open2($R2,$W2,@c2);
+select $W2;
+$|=1;
+while(<$R1>) {
+    info("1:",$_);
+    print $_;
+    $_=<$R2>;
+    last unless defined $_;
+    info("2:",$_);
+    print $W1 $_;
+}