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

	* stdio/linewrap.c: New file.
	* stdio/Makefile (routines): Add linewrap.
	* stdio/stdio.h [__USE_GNU]: Declare line_wrap_stream,
	line_unwrap_stream.

1 files changed, 353 insertions, 0 deletions

diff --git a/stdio/linewrap.c b/stdio/linewrap.c
new file mode 100644
index 0000000000..e821cc3575
--- /dev/null
+++ b/stdio/linewrap.c
@@ -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