ktrans: use stdio by default

The kbdtap is now given as the first argument instead.
The use of stdio allows for multiple taps to be chained
together in something like:

; </dev/kbdtap ktrans | progB | progC >/dev/kbdtap

2 files changed, 40 insertions, 36 deletions

diff --git a/sys/man/1/ktrans b/sys/man/1/ktrans
index a5acd1125..7662a9a5c 100644
--- a/sys/man/1/ktrans
+++ b/sys/man/1/ktrans
@@ -4,39 +4,41 @@ ktrans \- language transliterator
 .SH SYNOPSIS
 .B ktrans
 [
-.B -t
-.I kbdtap
-]
-[
 .B -l
 .I lang
 ]
+[
+.I kbdtap
+]
 .SH DESCRIPTION
 .I Ktrans
-provides a transliteration layer
-to keyboard input through reads and
-writes to
-.BR /dev/kbdtap .
-The
-.B -t
-flag changes the
+transliterates a stream of keyboard
+events. Without any arguments,
+.I ktrans
+reads events from standard input
+and writes out converted events to stdout.
+If a
 .I kbdtap
-file used. The
-.B -l
-flag changes the initial
-language.
+file is given, it is used for both
+input and output instead.
 .SH CONVERSION
-Conversion is done in two steps: An implicit layer
-that is used for direct mappings between ascii characters and
-an explicit multi rune conversion used for compound mappings.
+Conversion is done in two layers, an implicit
+layer for unambigious mappings, and an explicit
+layer for selecting one match out of a list of
+ambigious matches.
+.PP
+The implicit layer happens automatically as characters
+are input, transforming a consecutive set of key strokes
+in to their rune counterpart. A series of these runes can
+then be explicitely converted using ctrl-\\. Consecutive
+inputs of ctrl-\\ can then be used to cycle through all the
+matches. A newline may also be used to perform an explicit
+conversion, but will not cycle through other possible matches.
+.PP
+Input is always passed along, when a match is found
 .I Ktrans
-does implicit conversion by passing through characters
-as they are input. Then when a sequence of input is matched,
-backspaces are emitted to clear the input sequence and the matched
-rune sequence is emitted. The last 'word' of input may be then
-explicitely transliterated by typing ctrl-\\. A newline character also
-performs this lookup, but additional newline characters will not
-cycle through alternatives.
+will emit backspaces to clear the input sequence and replace
+it with the matched sequence.
 .SH CONTROL
 The language is selected by typing a control character:
 .TP
diff --git a/sys/src/cmd/ktrans/main.c b/sys/src/cmd/ktrans/main.c
index f41d3cfe3..6d6da0cf7 100644
--- a/sys/src/cmd/ktrans/main.c
+++ b/sys/src/cmd/ktrans/main.c
@@ -581,7 +581,7 @@ kbdsink(void*)
 void
 usage(void)
 {
-	fprint(2, "usage: %s [ -t tap ] [ -l lang ]\n", argv0);
+	fprint(2, "usage: %s [ -l lang ] [ kbdtap ]\n", argv0);
 	threadexits("usage");
 }
 
@@ -592,14 +592,9 @@ threadmain(int argc, char *argv[])
 {
 
 	char *jishoname, *zidianname;
-	char *tap;
 
-	tap = "/dev/kbdtap";
 	deflang = LangEN;
 	ARGBEGIN{
-	case 't':
-		tap = EARGF(usage());
-		break;
 	case 'l':
 		deflang = parselang(EARGF(usage()));
 		if(deflang < 0)
@@ -608,12 +603,19 @@ threadmain(int argc, char *argv[])
 	default:
 		usage();
 	}ARGEND;
-	if(argc != 0)
+	switch(argc){
+	case 0:
+		kbdin = 0;
+		kbdout = 1;
+		break;
+	case 1:
+		kbdin = kbdout = open(argv[0], ORDWR);
+		if(kbdin < 0)
+			sysfatal("failed to open kbdtap: %r");
+		break;
+	default:
 		usage();
-
-	kbdin = kbdout = open(tap, ORDWR);
-	if(kbdin < 0 || kbdout < 0)
-		sysfatal("failed to get keyboard: %r");
+	}
 
 	memset(backspace, '\b', sizeof backspace-1);
 	backspace[sizeof backspace-1] = '\0';