28ca945828
* stdio/linewrap.c: New file. * stdio/Makefile (routines): Add linewrap. * stdio/stdio.h [__USE_GNU]: Declare line_wrap_stream, line_unwrap_stream.
354 lines
9.8 KiB
C
354 lines
9.8 KiB
C
/* Word-wrapping and line-truncating streams.
|
||
Copyright (C) 1996 Free Software Foundation, Inc.
|
||
This file is part of the GNU C Library.
|
||
|
||
The GNU C Library is free software; you can redistribute it and/or
|
||
modify it under the terms of the GNU Library General Public License as
|
||
published by the Free Software Foundation; either version 2 of the
|
||
License, or (at your option) any later version.
|
||
|
||
The GNU C Library is distributed in the hope that it will be useful,
|
||
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
||
Library General Public License for more details.
|
||
|
||
You should have received a copy of the GNU Library General Public
|
||
License along with the GNU C Library; see the file COPYING.LIB. If
|
||
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
|
||
Cambridge, MA 02139, USA. */
|
||
|
||
#include <stdio.h>
|
||
#include <ctype.h>
|
||
#include <string.h>
|
||
#include <stdlib.h>
|
||
|
||
/* We keep this data for each line-wrapping stream. */
|
||
|
||
struct data
|
||
{
|
||
const size_t *lmargin, *rmargin; /* Left and right margins. */
|
||
const size_t *wrapmargin; /* Margin to wrap to, or null to truncate. */
|
||
size_t point; /* Current column of last chars flushed. */
|
||
|
||
/* Original cookie and hooks from the stream. */
|
||
void *cookie;
|
||
void (*output) (FILE *, int);
|
||
__io_close_fn *close;
|
||
__io_fileno_fn *fileno;
|
||
__io_seek_fn *seek;
|
||
};
|
||
|
||
/* Install our hooks into a stream. */
|
||
|
||
static inline void
|
||
wrap_stream (FILE *stream, struct data *d)
|
||
{
|
||
static void lwoutput (FILE *, int);
|
||
static __io_close_fn lwclose;
|
||
static __io_fileno_fn lwfileno;
|
||
|
||
stream->__cookie = d;
|
||
stream->__room_funcs.__output = &lwoutput;
|
||
stream->__io_funcs.__close = &lwclose;
|
||
stream->__io_funcs.__fileno = &lwfileno;
|
||
stream->__io_funcs.__seek = NULL; /* Cannot seek. */
|
||
}
|
||
|
||
/* Restore a stream to its original state. */
|
||
|
||
static inline void
|
||
unwrap_stream (FILE *stream, struct data *d)
|
||
{
|
||
stream->__cookie = d->cookie;
|
||
stream->__room_funcs.__output = d->output;
|
||
stream->__io_funcs.__close = d->close;
|
||
stream->__io_funcs.__fileno = d->fileno;
|
||
stream->__io_funcs.__seek = d->seek;
|
||
}
|
||
|
||
/* Cookie io functions that might get called on a wrapped stream.
|
||
Must pass the original cookie to the original functions. */
|
||
|
||
static int
|
||
lwclose (void *cookie)
|
||
{
|
||
struct data *d = cookie;
|
||
return (*d->close) (d->cookie);
|
||
}
|
||
|
||
static int
|
||
lwfileno (void *cookie)
|
||
{
|
||
struct data *d = cookie;
|
||
return (*d->fileno) (d->cookie);
|
||
}
|
||
|
||
/* This function is called when STREAM must be flushed.
|
||
C is EOF or a character to be appended to the buffer contents. */
|
||
|
||
static void
|
||
lwoutput (FILE *stream, int c)
|
||
{
|
||
char *buf, *nl;
|
||
size_t len;
|
||
|
||
/* Extract our data and restore the stream's original cookie
|
||
and output function so writes we do really go out. */
|
||
struct data *d = stream->__cookie;
|
||
unwrap_stream (stream, d);
|
||
|
||
/* Scan the buffer for newlines. */
|
||
for (buf = stream->__buffer;
|
||
(buf < stream->__bufp || (c != EOF && c != '\n')) && !stream->__error)
|
||
{
|
||
size_t r;
|
||
|
||
if (d->point == 0 && d->lmargin && *d->lmargin != 0)
|
||
{
|
||
/* We are starting a new line. Print spaces to the left margin. */
|
||
const size_t pad = *d->lmargin;
|
||
if (stream->__bufp + pad < stream->__put_limit)
|
||
{
|
||
/* We can fit in them in the buffer by moving the
|
||
buffer text up and filling in the beginning. */
|
||
memmove (buf + pad, buf, stream->__bufp - buf);
|
||
stream->__bufp += pad; /* Compensate for bigger buffer. */
|
||
memset (buf, ' ', pad); /* Fill in the spaces. */
|
||
buf += pad; /* Don't bother searching them. */
|
||
}
|
||
else
|
||
{
|
||
/* No buffer space for spaces. Must flush. */
|
||
size_t i;
|
||
char *olimit;
|
||
|
||
len = stream->__bufp - buf;
|
||
olimit = stream->__put_limit;
|
||
stream->__bufp = stream->__put_limit = buf;
|
||
for (i = 0; i < pad; ++i)
|
||
(*d->output) (stream, ' ');
|
||
stream->__put_limit = olimit;
|
||
memcpy (stream->__bufp, buf, len);
|
||
stream->__bufp += len;
|
||
}
|
||
d->point = pad;
|
||
}
|
||
|
||
len = stream->__bufp - buf;
|
||
nl = memchr (buf, '\n', len);
|
||
|
||
if (!nl)
|
||
{
|
||
/* The buffer ends in a partial line. */
|
||
|
||
if (!d->rmargin ||
|
||
d->point + len + (c != EOF && c != '\n') <= d->rmargin)
|
||
{
|
||
/* The remaining buffer text is a partial line and fits
|
||
within the maximum line width. Advance point for the
|
||
characters to be written and stop scanning. */
|
||
d->point += len;
|
||
break;
|
||
}
|
||
else
|
||
/* Set the end-of-line pointer for the code below to
|
||
the end of the buffer. */
|
||
nl = stream->__bufp;
|
||
}
|
||
else if (!d->rmargin || d->point + (nl - buf) <= d->rmargin)
|
||
{
|
||
/* The buffer contains a full line that fits within the maximum
|
||
line width. Reset point and scan the next line. */
|
||
d->point = 0;
|
||
buf = nl + 1;
|
||
continue;
|
||
}
|
||
|
||
/* This line is too long. */
|
||
r = *d->rmargin;
|
||
|
||
if (! d->wrapmargin)
|
||
{
|
||
/* Truncate the line by overwriting the excess with the
|
||
newline and anything after it in the buffer. */
|
||
if (nl < stream->__bufp)
|
||
{
|
||
memcpy (buf + (r - d->point), nl, stream->__bufp - nl);
|
||
stream->__bufp -= buf + (r - d->point) - nl;
|
||
/* Reset point for the next line and start scanning it. */
|
||
d->point = 0;
|
||
buf += r + 1; /* Skip full line plus \n. */
|
||
}
|
||
else
|
||
{
|
||
/* The buffer ends with a partial line that is beyond the
|
||
maximum line width. Advance point for the characters
|
||
written, and discard those past the max from the buffer. */
|
||
d->point += len;
|
||
stream->__bufp -= d->point - r;
|
||
if (c != '\n')
|
||
/* Swallow the extra character too. */
|
||
c = EOF;
|
||
break;
|
||
}
|
||
}
|
||
else
|
||
{
|
||
/* Do word wrap. Go to the column just past the maximum line
|
||
width and scan back for the beginning of the word there.
|
||
Then insert a line break. */
|
||
|
||
char *p, *nextline;
|
||
int i;
|
||
|
||
p = buf + (r + 1 - d->point);
|
||
while (p >= buf && !isblank (*p))
|
||
--p;
|
||
nextline = p + 1; /* This will begin the next line. */
|
||
|
||
if (nextline > buf)
|
||
{
|
||
/* Swallow separating blanks. */
|
||
do
|
||
--p;
|
||
while (isblank (*p));
|
||
nl = p + 1; /* The newline will replace the first blank. */
|
||
}
|
||
else
|
||
{
|
||
/* A single word that is greater than the maximum line width.
|
||
Oh well. Put it on an overlong line by itself. */
|
||
p = buf + (r + 1 - d->point);
|
||
/* Find the end of the long word. */
|
||
do
|
||
++p;
|
||
while (p < nl && !isblank (*p));
|
||
if (p == nl)
|
||
{
|
||
/* It already ends a line. No fussing required. */
|
||
d->point = 0;
|
||
buf = nl + 1;
|
||
continue;
|
||
}
|
||
/* We will move the newline to replace the first blank. */
|
||
nl = p;
|
||
/* Swallow separating blanks. */
|
||
do
|
||
++p;
|
||
while (isblank (*p));
|
||
/* The next line will start here. */
|
||
nextline = p;
|
||
}
|
||
|
||
/* Temporarily reset bufp to include just the first line. */
|
||
stream->__bufp = nl;
|
||
if (nextline - (nl + 1) < d->wrap)
|
||
/* The margin needs more blanks than we removed.
|
||
Output the first line so we can use the space. */
|
||
(*d->output) (stream, '\n');
|
||
else
|
||
/* We can fit the newline and blanks in before
|
||
the next word. */
|
||
*stream->__bufp++ = '\n';
|
||
|
||
/* Reset the counter of what has been output this line. */
|
||
d->point = 0;
|
||
|
||
/* Add blanks up to the wrap margin column. */
|
||
for (i = 0; i < d->wrap; ++i)
|
||
*stream->__bufp++ = ' ';
|
||
|
||
/* Copy the tail of the original buffer into the current buffer
|
||
position. */
|
||
if (stream->__bufp != nextline)
|
||
memcpy (stream->__bufp, nextline, buf + len - nextline);
|
||
len -= nextline - buf;
|
||
|
||
/* Continue the scan on the remaining lines in the buffer. */
|
||
buf = stream->__bufp;
|
||
|
||
/* Restore bufp to include all the remaining text. */
|
||
stream->__bufp += len;
|
||
}
|
||
}
|
||
|
||
if (!stream->__error)
|
||
{
|
||
(*d->output) (stream, c);
|
||
if (c == '\n')
|
||
d->point = 0;
|
||
else if (c != EOF)
|
||
++d->point;
|
||
}
|
||
|
||
wrap_stream (stream, d);
|
||
}
|
||
|
||
/* Modify STREAM so that it prefixes lines written on it with *LMARGIN
|
||
spaces and limits them to *RMARGIN columns total. If WRAP is not null,
|
||
words that extend past *RMARGIN are wrapped by replacing the whitespace
|
||
before them with a newline and *WRAP spaces. Otherwise, chars beyond
|
||
*RMARGIN are simply dropped until a newline. Returns STREAM after
|
||
modifying it, or NULL if there was an error. The pointers passed are
|
||
stored in the stream and so must remain valid until `line_unwrap_stream'
|
||
is called; the values pointed to can be changed between stdio calls. */
|
||
|
||
FILE *
|
||
line_wrap_stream (FILE *stream, size_t *lmargin, size_t *rmargin, size_t *wrap)
|
||
{
|
||
struct data *d = malloc (sizeof *d);
|
||
|
||
if (!d)
|
||
return NULL;
|
||
|
||
/* Ensure full setup before we start tweaking. */
|
||
fflush (stream);
|
||
|
||
/* Initialize our wrapping state. */
|
||
d->point = 0;
|
||
|
||
/* Save the original cookie and output and close hooks. */
|
||
d->cookie = stream->__cookie;
|
||
d->output = stream->__room_funcs.__output;
|
||
d->close = stream->__io_funcs.__close;
|
||
d->fileno = stream->__io_funcs.__fileno;
|
||
|
||
/* Take over the stream. */
|
||
wrap_stream (stream, d);
|
||
|
||
/* Line-wrapping streams are normally line-buffered. This is not
|
||
required, just assumed desired. The wrapping feature should continue
|
||
to work if the stream is switched to full or no buffering. */
|
||
stream->__linebuf = 1;
|
||
|
||
#define ref(arg) d->arg = arg
|
||
ref (lmargin);
|
||
ref (rmargin);
|
||
ref (wrap);
|
||
#undef ref
|
||
|
||
return stream;
|
||
}
|
||
|
||
/* Remove the hooks placed in STREAM by `line_wrap_stream'. */
|
||
|
||
void
|
||
line_unwrap_stream (FILE *stream)
|
||
{
|
||
struct data *d = stream->__cookie;
|
||
unwrap_stream (stream, d);
|
||
free (d);
|
||
}
|
||
|
||
#ifdef TEST
|
||
int
|
||
main (int argc, char **argv)
|
||
{
|
||
int c;
|
||
puts ("stopme");
|
||
line_wrap_stream (stdout, atoi (argv[1]), atoi (argv[2] ?: "-1"));
|
||
while ((c = getchar()) != EOF) putchar (c);
|
||
return 0;
|
||
}
|
||
#endif
|