521 lines
15 KiB
C
521 lines
15 KiB
C
/* Word-wrapping and line-truncating streams.
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Copyright (C) 1996 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If
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not, write to the Free Software Foundation, Inc., 675 Mass Ave,
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Cambridge, MA 02139, USA. */
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#include <stdio.h>
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#include <ctype.h>
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#include <string.h>
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#include <stdlib.h>
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#include <linewrap.h>
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void __line_wrap_output (FILE *, int);
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/* Install our hooks into a stream. */
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static inline void
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wrap_stream (FILE *stream, struct line_wrap_data *d)
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{
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static __io_close_fn lwclose;
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static __io_fileno_fn lwfileno;
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stream->__cookie = d;
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stream->__room_funcs.__output = &__line_wrap_output;
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stream->__io_funcs.__close = &lwclose;
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stream->__io_funcs.__fileno = &lwfileno;
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stream->__io_funcs.__seek = NULL; /* Cannot seek. */
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}
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/* Restore a stream to its original state. */
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static inline void
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unwrap_stream (FILE *stream, struct line_wrap_data *d)
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{
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stream->__cookie = d->cookie;
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stream->__room_funcs.__output = d->output;
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stream->__io_funcs.__close = d->close;
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stream->__io_funcs.__fileno = d->fileno;
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stream->__io_funcs.__seek = d->seek;
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}
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/* If WRAPPER_COOKIE points to a 0 pointer, then STREAM is assumed to be
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wrapped, and will be unwrapped, storing the wrapper cookie into
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WRAPPER_COOKIE. Otherwise, nothing is done. */
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static inline void
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ensure_unwrapped (FILE *stream, struct line_wrap_data **wrapper_cookie)
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{
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if (*wrapper_cookie == 0)
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{
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*wrapper_cookie = stream->__cookie;
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unwrap_stream (stream, *wrapper_cookie);
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}
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}
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/* If WRAPPER_COOKIE points to a non-0 pointer, then STREAM is assumed to
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*have been unwrapped with ensure_unwrapped, will be wrapped with
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*WRAPPER_COOKIE, and *WRAPPER_COOKIE zeroed. Otherwise, nothing is done. */
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static inline void
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ensure_wrapped (FILE *stream, struct line_wrap_data **wrapper_cookie)
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{
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if (*wrapper_cookie)
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{
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wrap_stream (stream, *wrapper_cookie);
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*wrapper_cookie = 0;
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}
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}
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/* Cookie io functions that might get called on a wrapped stream.
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Must pass the original cookie to the original functions. */
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static int
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lwclose (void *cookie)
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{
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struct line_wrap_data *d = cookie;
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return (*d->close) (d->cookie);
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}
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static int
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lwfileno (void *cookie)
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{
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struct line_wrap_data *d = cookie;
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return (*d->fileno) (d->cookie);
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}
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/* Process STREAM's buffer so that line wrapping is done from POINT_OFFS to
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the end of its buffer. If WRAPPER_COOKIE is 0, and it's necessary to
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flush some data, STREAM is unwrapped, and the line wrap stdio cookie
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stored in WRAPPER_COOKIE; otherwise, stream is assumed to already be
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unwrapped, and WRAPPER_COOKIE to point to the line wrap data. Returns C
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or EOF if C was output. */
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static inline int
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lwupdate (FILE *stream, int c, struct line_wrap_data **wrapper_cookie)
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{
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char *buf, *nl;
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size_t len;
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struct line_wrap_data *d = *wrapper_cookie ?: stream->__cookie;
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/* Scan the buffer for newlines. */
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buf = stream->__buffer + d->point_offs;
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while ((buf < stream->__bufp || (c != EOF && c != '\n')) && !stream->__error)
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{
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size_t r;
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if (d->point_col == 0 && d->lmargin != 0)
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{
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/* We are starting a new line. Print spaces to the left margin. */
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const size_t pad = d->lmargin;
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if (stream->__bufp + pad < stream->__put_limit)
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{
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/* We can fit in them in the buffer by moving the
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buffer text up and filling in the beginning. */
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memmove (buf + pad, buf, stream->__bufp - buf);
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stream->__bufp += pad; /* Compensate for bigger buffer. */
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memset (buf, ' ', pad); /* Fill in the spaces. */
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buf += pad; /* Don't bother searching them. */
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}
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else
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{
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/* No buffer space for spaces. Must flush. */
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size_t i;
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char *olimit;
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ensure_unwrapped (stream, wrapper_cookie);
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len = stream->__bufp - buf;
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olimit = stream->__put_limit;
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stream->__bufp = stream->__put_limit = buf;
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for (i = 0; i < pad; ++i)
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(*d->output) (stream, ' ');
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stream->__put_limit = olimit;
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memmove (stream->__bufp, buf, len);
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stream->__bufp += len;
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}
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d->point_col = pad;
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}
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len = stream->__bufp - buf;
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nl = memchr (buf, '\n', len);
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if (d->point_col < 0)
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d->point_col = 0;
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if (!nl)
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{
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/* The buffer ends in a partial line. */
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if (d->point_col + len + (c != EOF && c != '\n') < d->rmargin)
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{
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/* The remaining buffer text is a partial line and fits
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within the maximum line width. Advance point for the
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characters to be written and stop scanning. */
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d->point_col += len;
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break;
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}
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else
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/* Set the end-of-line pointer for the code below to
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the end of the buffer. */
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nl = stream->__bufp;
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}
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else if (d->point_col + (nl - buf) < d->rmargin)
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{
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/* The buffer contains a full line that fits within the maximum
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line width. Reset point and scan the next line. */
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d->point_col = 0;
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buf = nl + 1;
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continue;
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}
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/* This line is too long. */
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r = d->rmargin - 1;
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if (d->wmargin < 0)
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{
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/* Truncate the line by overwriting the excess with the
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newline and anything after it in the buffer. */
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if (nl < stream->__bufp)
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{
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memmove (buf + (r - d->point_col), nl, stream->__bufp - nl);
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stream->__bufp -= buf + (r - d->point_col) - nl;
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/* Reset point for the next line and start scanning it. */
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d->point_col = 0;
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buf += r + 1; /* Skip full line plus \n. */
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}
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else
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{
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/* The buffer ends with a partial line that is beyond the
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maximum line width. Advance point for the characters
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written, and discard those past the max from the buffer. */
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d->point_col += len;
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stream->__bufp -= d->point_col - r;
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if (c != '\n')
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/* Swallow the extra character too. */
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c = EOF;
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break;
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}
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}
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else
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{
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/* Do word wrap. Go to the column just past the maximum line
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width and scan back for the beginning of the word there.
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Then insert a line break. */
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char *p, *nextline;
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int i;
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p = buf + (r + 1 - d->point_col);
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while (p >= buf && !isblank (*p))
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--p;
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nextline = p + 1; /* This will begin the next line. */
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if (nextline > buf)
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{
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/* Swallow separating blanks. */
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do
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--p;
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while (isblank (*p));
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nl = p + 1; /* The newline will replace the first blank. */
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}
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else
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{
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/* A single word that is greater than the maximum line width.
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Oh well. Put it on an overlong line by itself. */
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p = buf + (r + 1 - d->point_col);
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/* Find the end of the long word. */
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do
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++p;
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while (p < nl && !isblank (*p));
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if (p == nl)
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{
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/* It already ends a line. No fussing required. */
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d->point_col = 0;
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buf = nl + 1;
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continue;
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}
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/* We will move the newline to replace the first blank. */
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nl = p;
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/* Swallow separating blanks. */
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do
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++p;
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while (isblank (*p));
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/* The next line will start here. */
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nextline = p;
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}
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/* Temporarily reset bufp to include just the first line. */
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stream->__bufp = nl;
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if (nextline - (nl + 1) < d->wmargin)
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/* The margin needs more blanks than we removed.
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Output the first line so we can use the space. */
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{
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ensure_unwrapped (stream, wrapper_cookie);
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(*d->output) (stream, '\n');
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}
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else
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/* We can fit the newline and blanks in before
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the next word. */
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*stream->__bufp++ = '\n';
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/* Reset the counter of what has been output this line. If wmargin
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is 0, we want to avoid the lmargin getting added, so we set
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point_col to a magic value of -1 in that case. */
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d->point_col = d->wmargin ? d->wmargin : -1;
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/* Add blanks up to the wrap margin column. */
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for (i = 0; i < d->wmargin; ++i)
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*stream->__bufp++ = ' ';
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/* Copy the tail of the original buffer into the current buffer
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position. */
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if (stream->__bufp != nextline)
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memmove (stream->__bufp, nextline, buf + len - nextline);
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len -= nextline - buf;
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/* Continue the scan on the remaining lines in the buffer. */
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buf = stream->__bufp;
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/* Restore bufp to include all the remaining text. */
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stream->__bufp += len;
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}
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}
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/* Remember that we've scanned as far as the end of the buffer. */
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d->point_offs = stream->__bufp - stream->__buffer;
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return c;
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}
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/* This function is called when STREAM must be flushed.
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C is EOF or a character to be appended to the buffer contents. */
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void
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__line_wrap_output (FILE *stream, int c)
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{
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struct line_wrap_data *d = 0;
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c = lwupdate (stream, c, &d);
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if (!stream->__error)
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{
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ensure_unwrapped (stream, &d);
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(*d->output) (stream, c);
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d->point_offs = 0; /* The buffer now holds nothing. */
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if (c == '\n')
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d->point_col = 0;
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else if (c != EOF)
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++d->point_col;
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}
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ensure_wrapped (stream, &d);
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}
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/* Modify STREAM so that it prefixes lines written on it with LMARGIN spaces
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and limits them to RMARGIN columns total. If WMARGIN >= 0, words that
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extend past RMARGIN are wrapped by replacing the whitespace before them
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with a newline and WMARGIN spaces. Otherwise, chars beyond RMARGIN are
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simply dropped until a newline. Returns STREAM after modifying it, or
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NULL if there was an error. */
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FILE *
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line_wrap_stream (FILE *stream, size_t lmargin, size_t rmargin, ssize_t wmargin)
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{
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struct line_wrap_data *d = malloc (sizeof *d);
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if (!d)
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return NULL;
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/* Ensure full setup before we start tweaking. */
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fflush (stream);
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/* Initialize our wrapping state. */
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d->point_col = 0;
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d->point_offs = 0;
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/* Save the original cookie and output and close hooks. */
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d->cookie = stream->__cookie;
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d->output = stream->__room_funcs.__output;
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d->close = stream->__io_funcs.__close;
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d->fileno = stream->__io_funcs.__fileno;
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/* Take over the stream. */
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wrap_stream (stream, d);
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/* Line-wrapping streams are normally line-buffered. This is not
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required, just assumed desired. The wrapping feature should continue
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to work if the stream is switched to full or no buffering. */
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stream->__linebuf = 1;
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d->lmargin = lmargin;
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d->rmargin = rmargin;
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d->wmargin = wmargin;
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return stream;
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}
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/* Remove the hooks placed in STREAM by `line_wrap_stream'. */
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void
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line_unwrap_stream (FILE *stream)
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{
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struct line_wrap_data *d = stream->__cookie;
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unwrap_stream (stream, d);
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free (d);
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}
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/* Functions on wrapped streams. */
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/* Returns true if STREAM is line wrapped. */
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inline int
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line_wrapped (FILE *stream)
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{
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return (stream->__room_funcs.__output == &__line_wrap_output);
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}
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/* If STREAM is not line-wrapped, return 0. Otherwise all pending text
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buffered text in STREAM so that the POINT_OFFS field refers to the last
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position in the stdio buffer, and return the line wrap state object for
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STREAM. Since all text has been processed, this means that (1) the
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POINT_COL field refers to the column at which any new text would be added,
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and (2) any changes to the margin parameters will only affect new text. */
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struct line_wrap_data *
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__line_wrap_update (FILE *stream)
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{
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if (line_wrapped (stream))
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{
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struct line_wrap_data *d = stream->__cookie, *wc = 0;
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if (stream->__linebuf_active)
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/* This is an active line-buffered stream, so its put-limit is set to
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the beginning of the buffer in order to force a __flshfp call on
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each putc (see below). We undo this hack here (by setting the
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limit to the end of the buffer) to simplify the interface with the
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output-room function. */
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stream->__put_limit = stream->__buffer + stream->__bufsize;
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lwupdate (stream, EOF, &wc);
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if (stream->__linebuf)
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{
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/* This is a line-buffered stream, and it is now ready to do some
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output. We call this an "active line-buffered stream". We set
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the put_limit to the beginning of the buffer, so the next `putc'
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call will force a call to flshfp. Setting the linebuf_active
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flag tells the code above (on the next call) to undo this
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hackery. */
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stream->__put_limit = stream->__buffer;
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stream->__linebuf_active = 1;
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}
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ensure_wrapped (stream, &wc);
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return d;
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}
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else
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return 0;
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}
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/* If STREAM is not line-wrapped return -1, else return its left margin. */
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inline size_t
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line_wrap_lmargin (FILE *stream)
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{
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if (! line_wrapped (stream))
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return -1;
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return ((struct line_wrap_data *)stream->__cookie)->lmargin;
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}
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/* If STREAM is not line-wrapped return -1, else set its left margin to
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LMARGIN and return the old value. */
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inline size_t
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line_wrap_set_lmargin (FILE *stream, size_t lmargin)
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{
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struct line_wrap_data *d = __line_wrap_update (stream);
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if (d)
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{
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size_t old = d->lmargin;
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d->lmargin = lmargin;
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return old;
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}
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else
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return -1;
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}
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/* If STREAM is not line-wrapped return -1, else return its left margin. */
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inline size_t
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line_wrap_rmargin (FILE *stream)
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{
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if (! line_wrapped (stream))
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return -1;
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return ((struct line_wrap_data *)stream->__cookie)->rmargin;
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}
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/* If STREAM is not line-wrapped return -1, else set its right margin to
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RMARGIN and return the old value. */
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inline size_t
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line_wrap_set_rmargin (FILE *stream, size_t rmargin)
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{
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struct line_wrap_data *d = __line_wrap_update (stream);
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if (d)
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{
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size_t old = d->rmargin;
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d->rmargin = rmargin;
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return old;
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}
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else
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return -1;
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}
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/* If STREAM is not line-wrapped return -1, else return its wrap margin. */
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inline size_t
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line_wrap_wmargin (FILE *stream)
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{
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if (! line_wrapped (stream))
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return -1;
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return ((struct line_wrap_data *)stream->__cookie)->wmargin;
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}
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/* If STREAM is not line-wrapped return -1, else set its left margin to
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WMARGIN and return the old value. */
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inline size_t
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line_wrap_set_wmargin (FILE *stream, size_t wmargin)
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{
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struct line_wrap_data *d = __line_wrap_update (stream);
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if (d)
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{
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size_t old = d->wmargin;
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d->wmargin = wmargin;
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return old;
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}
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else
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return -1;
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}
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/* If STREAM is not line-wrapped return -1, else return the column number of
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the current output point. */
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inline size_t
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line_wrap_point (FILE *stream)
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{
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struct line_wrap_data *d = __line_wrap_update (stream);
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return d ? (d->point_col >= 0 ? d->point_col : 0) : -1;
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}
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#ifdef TEST
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int
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main (int argc, char **argv)
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{
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int c;
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puts ("stopme");
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line_wrap_stream (stdout, atoi (argv[1]), atoi (argv[2] ?: "-1"));
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while ((c = getchar()) != EOF) putchar (c);
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return 0;
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}
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#endif
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