/*-
* Copyright (c) 2012 Ed Schouten <ed@FreeBSD.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <ctype.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
static char *queue = NULL;
static size_t queuelen = 0, queuesize = 0;
static off_t column = 0;
static void
savebyte(char c)
{
if (queuelen >= queuesize) {
queuesize += 128;
queue = realloc(queue, queuesize);
if (queue == NULL) {
perror("malloc");
exit(1);
}
}
queue[queuelen++] = c;
switch (c) {
case '\n':
column = 0;
break;
case ' ':
column++;
break;
case '\t':
column = (column / 8 + 1) * 8;
break;
}
}
static bool
peekbyte(size_t back, char c)
{
return (queuelen >= back && queue[queuelen - back] == c);
}
static void
savewhite(char c, bool leading)
{
off_t ncolumn;
switch (c) {
case '\n':
if (leading) {
/* Remove empty lines before input. */
queuelen = 0;
column = 0;
} else {
/* Remove trailing whitespace. */
while (peekbyte(1, ' ') || peekbyte(1, '\t'))
queuelen--;
/* Remove redundant empty lines. */
if (peekbyte(2, '\n') && peekbyte(1, '\n'))
return;
savebyte('\n');
}
break;
case ' ':
savebyte(' ');
break;
case '\t':
/* Convert preceding spaces to tabs. */
ncolumn = (column / 8 + 1) * 8;
while (peekbyte(1, ' ')) {
queuelen--;
column--;
}
while (column < ncolumn)
savebyte('\t');
break;
}
}
static void
printwhite(void)
{
off_t i;
/* Merge spaces at the start of a sentence to tabs if possible. */
if ((column % 8) == 0) {
for (i = 0; i < column; i++)
if (!peekbyte(i + 1, ' '))
break;
if (i == column) {
queuelen -= column;
for (i = 0; i < column; i += 8)
queue[queuelen++] = '\t';
}
}
if (fwrite(queue, 1, queuelen, stdout) != queuelen) {
perror("write");
exit(1);
}
queuelen = 0;
}
static char
readchar(void)
{
int c;
c = getchar();
if (c == EOF && ferror(stdin)) {
perror("read");
exit(1);
}
return (c);
}
static void
writechar(char c)
{
if (putchar(c) == EOF) {
perror("write");
exit(1);
}
/* XXX: Multi-byte characters. */
column++;
}
int
main(void)
{
int c;
bool leading = true;
while ((c = readchar()) != EOF) {
if (isspace(c))
/* Save whitespace. */
savewhite(c, leading);
else {
/* Reprint whitespace and print regular character. */
printwhite();
writechar(c);
leading = false;
}
}
/* Terminate non-empty files with a newline. */
if (!leading)
writechar('\n');
return (0);
}