Add unexpand(1)

LICENSE

@@ -26,6 +26,7 @@ MIT/X Consortium License
 © 2014 Silvan Jegen <s.jegen@gmail.com>
 © 2014 Laslo Hunhold <dev@frign.de>
 © 2014 Daniel Bainton <dpb@driftaway.org>
+© 2014 Tuukka Kataja <stuge@xor.fi>
 
 Permission is hereby granted, free of charge, to any person obtaining a
 copy of this software and associated documentation files (the "Software"),

Makefile

@@ -89,6 +89,7 @@ SRC = \
 	uudecode.c \
 	uuencode.c \
 	uname.c    \
+	unexpand.c \
 	uniq.c     \
 	unlink.c   \
 	seq.c      \

README

@@ -11,8 +11,8 @@ The following programs are currently implemented:
     kill ln  ls mc md5sum mkdir  mkfifo mktemp mv nice  nl nohup paste
     printenv  pwd readlink  renice rm  rmdir sleep  setsid sort  split
     sponge strings sync  tail tar tee test touch tr  true tty uudecode
-    uuencode  uname uniq  unlink  seq sha1sum  sha256sum sha512sum  wc
-    xargs yes
+    uuencode  uname   unexpand  uniq  unlink  seq   sha1sum  sha256sum
+    sha512sum wc xargs yes
 
 sbase is mostly following POSIX but we deviate wherever we think it is
 appropriate.

TODO

@@ -11,8 +11,6 @@ test [expression...]
 tr:
 	support for character classes [:alnum:]
 
-unexpand [-a] [-t N] [file...]
-
 od/hd
 
 uuencode, uudecode:

expand.1

@@ -18,4 +18,5 @@ Expand tabs to
 .I n
 spaces.  We currently support only a single numerical argument.
 .SH SEE ALSO
+.IR unexpand (1),
 .IR fold (1)

unexpand.1

@@ -0,0 +1,25 @@
+.TH EXPAND 1 sbase\-VERSION
+.SH NAME
+unexpand \- convert blanks to tabs
+.SH SYNOPSIS
+.B unexpand
+.RB [ \-a ]
+.RB [ \-t
+.IR n ]
+.RI [ file ...]
+.SH DESCRIPTION
+unexpand processes the named files or the standard input, writing the
+standard output with consecutive blanks (spaces and tabs) converted
+into tabs. Backspace characters are preserved into the output and
+decrement the column count for tab calculations.
+.SH OPTIONS
+.TP
+.BI \-a
+convert blanks to tabs everywhere, not just at the start of lines
+.TP
+.BI \-t " n"
+set tab size to
+.I n
+spaces (default: 8)
+.SH SEE ALSO
+.IR expand (1)

unexpand.c

@@ -0,0 +1,140 @@
+/* See LICENSE file for copyright and license details. */
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <wchar.h>
+#include "util.h"
+
+typedef struct {
+	FILE *fp;
+	const char *name;
+} Fdescr;
+
+static void unexpand(Fdescr *dsc);
+
+static bool aflag = false;
+static int tabsize = 8;
+
+static void
+usage(void)
+{
+	eprintf("usage: %s [-a] [-t n] [file ...]\n", argv0);
+}
+
+int
+main(int argc, char *argv[])
+{
+	Fdescr dsc;
+	FILE *fp;
+
+	ARGBEGIN {
+	case 't':
+		tabsize = estrtol(EARGF(usage()), 0);
+		if(tabsize <= 0)
+			eprintf("unexpand: invalid tabsize\n", argv[0]);
+		/* Fallthrough: -t implies -a */
+	case 'a':
+		aflag = true;
+		break;
+	default:
+		usage();
+	} ARGEND;
+
+	if (argc == 0) {
+		dsc.name = "<stdin>";
+		dsc.fp = stdin;
+		unexpand(&dsc);
+	} else {
+		for (; argc > 0; argc--, argv++) {
+			if (!(fp = fopen(*argv, "r"))) {
+				weprintf("fopen %s:", *argv);
+				continue;
+			}
+			dsc.name = *argv;
+			dsc.fp = fp;
+			unexpand(&dsc);
+			fclose(fp);
+		}
+	}
+
+	return EXIT_SUCCESS;
+}
+
+static wint_t
+in(Fdescr *f)
+{
+	wint_t c = fgetwc(f->fp);
+
+	if (c == WEOF && ferror(f->fp))
+		eprintf("'%s' read error:", f->name);
+
+	return c;
+}
+
+static void
+out(wint_t c)
+{
+	putwchar(c);
+	if (ferror(stdout))
+		eprintf("write error:");
+}
+
+static void
+unexpandspan(unsigned int n, unsigned int col)
+{
+	unsigned int off = (col-n) % tabsize;
+
+	if(n + off >= tabsize && n > 1)
+		n += off;
+
+	for(; n >= tabsize; n -= tabsize)
+		out('\t');
+	while(n--)
+		out(' ');
+}
+
+static void
+unexpand(Fdescr *dsc)
+{
+	unsigned int n = 0, col = 0;
+	bool bol = true;
+	wint_t c;
+
+	while ((c = in(dsc)) != EOF) {
+		switch (c) {
+		case ' ':
+			if (bol || aflag)
+				n++;
+			col++;
+			break;
+		case '\t':
+			if (bol || aflag)
+				n += tabsize - col % tabsize;
+			col += tabsize - col % tabsize;
+			break;
+		case '\b':
+			if (bol || aflag)
+				unexpandspan(n, col);
+			col -= (col > 0);
+			n = 0;
+			bol = false;
+			break;
+		case '\n':
+			if (bol || aflag)
+				unexpandspan(n, col);
+			n = col = 0;
+			bol = true;
+			break;
+		default:
+			if (bol || aflag)
+				unexpandspan(n, col);
+			n = 0;
+			col++;
+			bol = false;
+		}
+		if ((c != ' ' && c != '\t') || (!aflag && !bol))
+			out(c);
+	}
+	if (n > 0 && (bol || aflag))
+		unexpandspan(n, col);
+}