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Mon May 6 09:51:05 1996 Roland McGrath <roland@delasyd.gnu.ai.mit.edu>

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* stdio/linewrap.c: New file.
	* stdio/Makefile (routines): Add linewrap.
	* stdio/stdio.h [__USE_GNU]: Declare line_wrap_stream,
	line_unwrap_stream.
This commit is contained in:
Roland McGrath 1996-05-07 14:49:12 +00:00
parent cee8df033b
commit 28ca945828
3 changed files with 372 additions and 3 deletions
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4
stdio/Makefile
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@ -1,4 +1,4 @@
# Copyright (C) 1991, 1992, 1993, 1994, 1995 Free Software Foundation, Inc.
# Copyright (C) 1991, 92, 93, 94, 95, 96 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
@ -36,7 +36,7 @@ routines := \
getdelim \
fclose fflush \
vdprintf vsnprintf vsprintf vasprintf vsscanf \
memstream obstream \
memstream obstream linewrap \
internals sysd-stdio pipestream stdio_init libc_fatal
aux := defs glue

353
stdio/linewrap.c Normal file
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@ -0,0 +1,353 @@
/* 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

18
stdio/stdio.h
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@ -1,4 +1,4 @@
/* Copyright (C) 1991, 1992, 1993, 1994, 1995 Free Software Foundation, Inc.
/* Copyright (C) 1991, 92, 93, 94, 95, 96 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
@ -353,6 +353,22 @@ extern FILE *fmemopen __P ((__ptr_t __s, size_t __len, __const char *__modes));
necessary. *BUFLOC and *SIZELOC are updated with the buffer's location
and the number of characters written on fflush or fclose. */
extern FILE *open_memstream __P ((char **__bufloc, size_t *__sizeloc));
/* 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. */
extern FILE *line_wrap_stream __P ((FILE *__stream,
size_t *__lmargin, size_t *__rmargin,
size_t *__wrap));
/* Remove the hooks placed in STREAM by `line_wrap_stream'. */
extern void line_unwrap_stream __P ((FILE *__stream));
#endif