Add the tr program including man page

Makefile

@@ -81,6 +81,7 @@ SRC = \
 	tee.c      \
 	test.c     \
 	touch.c    \
+	tr.c       \
 	true.c     \
 	tty.c      \
 	uname.c    \

tr.1

@@ -0,0 +1,50 @@
+.TH TR 1 sbase\-VERSION
+.SH NAME
+tr \- translate characters
+.SH SYNOPSIS
+.B tr
+.RB set1
+.RI [ set2 ]
+.SH DESCRIPTION
+.B tr
+reads input from stdin replacing every character in
+.B set1
+with the character at the same index in
+.B set2.
+If set2 is not given
+.B tr
+deletes the characters in set1 from the input.
+
+Sets are specified as strings of characters. Almost all represent themselves. The following ones will be interpreted:
+.TP
+\e\e
+backslash
+.TP
+\ea
+audible BEL
+.TP
+\ef
+form feed
+.TP
+\en
+new line
+.TP
+\er
+return
+.TP
+\et
+horizontal tab
+.TP
+\ev
+vertical tab
+.PP
+If set1 is longer than set2
+.B tr
+will map all the remaining characters to the last one in set2. In case set2 is longer than set1, the remaining characters from set2 will be ignored.
+.B
+.SH NOTES
+.B tr
+is Unicode-aware but does not yet handle character classes (e.g. [:alnum:] or [:digit:]).
+.SH SEE ALSO
+.IR sed(1)
+.IR awk(1)

tr.c

@@ -0,0 +1,151 @@
+/* See LICENSE file for copyright and license details. */
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <locale.h>
+#include <wchar.h>
+#include "text.h"
+#include "util.h"
+
+static void
+usage(void)
+{
+	eprintf("usage: %s set1 [set2]\n", argv0);
+}
+
+void
+handleescapes(char *s)
+{
+	switch(*s) {
+	case 'n':
+		*s = '\n';
+		break;
+	case 't':
+		*s = '\t';
+		break;
+	case '\\':
+		*s = '\\';
+		break;
+	case 'r':
+		*s = '\r';
+		break;
+	case 'f':
+		*s = '\f';
+		break;
+	case 'a':
+		*s = '\a';
+		break;
+	case 'b':
+		*s = '\b';
+		break;
+	case 'v':
+		*s = '\v';
+		break;
+	}
+}
+
+void
+parsemapping(const char *set1, const char *set2, wchar_t *mappings)
+{
+	char *s;
+	wchar_t runeleft;
+	wchar_t runeright;
+	int leftbytes;
+	int rightbytes;
+	size_t n = 0;
+	size_t lset2;
+
+	if(set2) {
+		lset2 = strnlen(set2, 255 * sizeof(wchar_t));
+	} else {
+		set2 = &set1[0];
+		lset2 = 0;
+	}
+
+	s = (char *)set1;
+	while(*s) {
+		if(*s == '\\')
+			handleescapes(++s);
+		leftbytes = mbtowc(&runeleft, s, 4);
+		if(set2[n] != '\0')
+			rightbytes = mbtowc(&runeright, set2 + n, 4);
+		mappings[runeleft] = runeright;
+		s += leftbytes;
+		if(n < lset2)
+			n += rightbytes;
+	}
+}
+
+void
+maptonull(const wchar_t *mappings, char *in)
+{
+	const char *s;
+	wchar_t runeleft;
+	int leftbytes = 0;
+
+	s = in;
+	while(*s) {
+		leftbytes = mbtowc(&runeleft, s, 4);
+		if(!mappings[runeleft])
+			putwchar(runeleft);
+		s += leftbytes;
+	}
+}
+
+void
+maptoset(const wchar_t *mappings, char *in)
+{
+	const char *s;
+	wchar_t runeleft;
+	int leftbytes = 0;
+
+	s = in;
+	while(*s) {
+		leftbytes = mbtowc(&runeleft, s, 4);
+		if(!mappings[runeleft])
+			putwchar(runeleft);
+		else
+			putwchar(mappings[runeleft]);
+		s += leftbytes;
+	}
+}
+
+int
+main(int argc, char *argv[])
+{
+	wchar_t *mappings;
+	char *buf = NULL;
+	size_t size = 0;
+	void (*mapfunc)(const wchar_t*, char*);
+
+	setlocale(LC_ALL, "");
+
+	mappings = (wchar_t *)mmap(NULL, 0x110000 * sizeof(wchar_t),
+				   PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, -1, 0);
+
+	ARGBEGIN {
+	default:
+		usage();
+	} ARGEND;
+
+	if(argc == 0)
+		usage();
+
+	if(argc >= 2) {
+		parsemapping(argv[0], argv[1], mappings);
+		mapfunc = maptoset;
+	} else {
+		parsemapping(argv[0], NULL, mappings);
+		mapfunc = maptonull;
+	}
+
+	while(afgets(&buf, &size, stdin))
+		mapfunc(mappings, buf);
+	free(buf);
+	if(ferror(stdin))
+		eprintf("<stdin>: read error:");
+
+	return EXIT_SUCCESS;
+}