Adding `warnscale' and `spreadwarn' requests, based on a patch from

Jeffrey Friedl <jfriedl@yahoo.com>.

* src/roff/troff/input.cc (spread_limit, warn_scale,
warn_scaling_indicator): New global variables.
(warnscale_request, spreadwarn_requests): New functions.
(main): Initialize `warn_scale' and `warn_scaling_indicator'.
(init_input_requests): Updated.
(error_type): Add `OUTPUT_WARNING'.
(do_error): Handle it.
(output_warning): New warning function which shows output location.
* src/roff/troff/env.h (spread_limit): New external variable.
* src/roff/troff/env.cc (environment::choose_breakpoint): Use
`output_warning'.
(distribute_space): Emit warning if added space is larger than
`spread_limit'.
(environment::possibly_break_line): Emit warning if a line can't
be adjusted on both sides.

* doc/groff.texinfo, man/groff_diff.man, man/groff.man: Document it.

9 files changed, 244 insertions, 22 deletions

diff --git a/ChangeLog b/ChangeLog
index 8ebd7841..1d9cd82c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,26 @@
+2002-05-11  Werner LEMBERG  <wl@gnu.org>
+
+	Adding `warnscale' and `spreadwarn' requests, based on a patch from
+	Jeffrey Friedl <jfriedl@yahoo.com>.
+
+	* src/roff/troff/input.cc (spread_limit, warn_scale,
+	warn_scaling_indicator): New global variables.
+	(warnscale_request, spreadwarn_requests): New functions.
+	(main): Initialize `warn_scale' and `warn_scaling_indicator'.
+	(init_input_requests): Updated.
+	(error_type): Add `OUTPUT_WARNING'.
+	(do_error): Handle it.
+	(output_warning): New warning function which shows output location.
+	* src/roff/troff/env.h (spread_limit): New external variable.
+	* src/roff/troff/env.cc (environment::choose_breakpoint): Use
+	`output_warning'.
+	(distribute_space): Emit warning if added space is larger than
+	`spread_limit'.
+	(environment::possibly_break_line): Emit warning if a line can't
+	be adjusted on both sides.
+
+	* doc/groff.texinfo, man/groff_diff.man, man/groff.man: Document it.
+
 2002-05-08  Werner LEMBERG  <wl@gnu.org>
 
 	* src/roff/troff/node.cc (special_node::special_node): Use
diff --git a/NEWS b/NEWS
index c7115606..fe2badbf 100644
--- a/NEWS
+++ b/NEWS
@@ -547,6 +547,12 @@ o Two new requests `tm1' and `tmc' have been added to improve writing
   messages to the terminal.  `tm1' is similar to `tm' but allows leading
   whitespace.  `tmc' is similar to `tm1' but doesn't emit a final newline.
 
+o The new `spreadwarn' request will make troff warn if spaces in an output
+  line are widened by a given limit or more.
+
+o Use `warnscale' to change the scaling indicator troff will use for
+  warning messages.
+
 o A new request `dei' (define indirect) has been added.  The first and
   second parameter of `dei' are taken from string registers rather than
   directly; this very special request is needed to make `trace.tmac'
diff --git a/doc/groff.texinfo b/doc/groff.texinfo
index b28ef4b5..e2b4fbf0 100644
--- a/doc/groff.texinfo
+++ b/doc/groff.texinfo
@@ -5926,6 +5926,15 @@ The @code{\:} escape inserts a zero-width break point
 @Example
 ... check the /var/log/\:httpd/\:access_log file ...
 @endExample
+
+@cindex @code{\X}, followed by @code{\%}
+@cindex @code{\Y}, followed by @code{\%}
+@cindex @code{\%}, following @code{\X} or @code{\Y}
+Note that @code{\X} and @code{\Y} start a word, that is, the @code{\%}
+escape in (say) @w{@samp{ \X'...'\%foobar}} and
+@w{@samp{ \Y'...'\%foobar}} no longer prevents hyphenation but inserts
+a hyphenation point at the beginning of @samp{foobar}; most likely
+this isn't what you want to do.
 @endDefesc
 
 @Defreq {hc, [@Var{char}]}
@@ -11985,8 +11994,38 @@ to set the maximum number of objects on the input stack.
 If @code{slimit} is less than or equal to@w{ }0,
 there is no limit set.
 With no limit, a buggy recursive macro can exhaust virtual memory.
+
+The default value is 1000; this is a compile-time constant.
 @endDefreg
 
+@Defreq {warnscale, si}
+Set the scaling indicator used in warnings to @var{si}.  Valid values for
+@var{si} are @samp{u}, @samp{i}, @samp{c}, @samp{p}, and @samp{P}.  At
+startup, it is set to @samp{i}.
+@endDefreq
+
+@Defreq {spreadwarn, [@Var{limit}]}
+Make @code{gtroff} emit a warning if the additional space inserted for
+each space between words in an output line is larger or equal to
+@var{limit}.  A negative value is changed to zero; no argument toggles the
+warning on and off without changing @var{limit}.  The default scaling
+indicator is @samp{m}.  At startup, @code{spreadwarn} is deactivated, and
+@var{limit} is set to 3@dmn{m}.
+
+For example,
+
+@Example
+.spreadwarn 0.2m
+@endExample
+
+@noindent
+will cause a warning if @code{gtroff} must add 0.2@dmn{m} or more for each
+interword space in a line.
+
+This request is active only if text is justified to both margins (using
+@w{@samp{.ad b}}).
+@endDefreq
+
 @cindex warnings
 @code{gtroff} has command line options for printing out more warnings
 (@option{-w}) and for printing backtraces (@option{-b}) when a warning
diff --git a/man/groff.man b/man/groff.man
index 133a39c4..bfa0420e 100644
--- a/man/groff.man
+++ b/man/groff.man
@@ -2,7 +2,7 @@
 .ig
 groff.man
 
-Last update: 21 Apr 2002
+Last update: 11 May 2002
 
 This file is part of groff, the GNU roff type-setting system.
 
@@ -746,21 +746,21 @@ There is a sophisticated interface for handling tab positions.
 A
 .B numerical value
 is a signed or unsigned integer or float with or without an appended
-scale indicator.
+scaling indicator.
 .
 A
-.B scale indicator
+.B scaling indicator
 is a one-character abbreviation for a unit of measurement.
 .
-A number followed by a scale indicator signifies a size value.
+A number followed by a scaling indicator signifies a size value.
 .
-By default, numerical values do not have a scale indicator, i.e., they
+By default, numerical values do not have a scaling indicator, i.e., they
 are normal numbers.
 .
 .P
 The
 .I roff
-language defines the following scale indicators.
+language defines the following scaling indicators.
 .
 .
 .P
@@ -1385,7 +1385,7 @@ or
 .BR grey .
 .I component
 can be single components specified as fractions in the range 0 to 1
-(default scale indicator\~\c
+(default scaling indicator\~\c
 .scaleindicator f ),
 as a string of two-digit hexadecimal color components with a leading
 .BR # ,
@@ -1436,7 +1436,7 @@ but with compatibility mode switched off during string expansion.
 .REQ .dt N trap
 Set diversion trap to position
 .I N
-(default scale indicator\~\c
+(default scaling indicator\~\c
 .scaleindicator v ).
 .
 .REQ .ec
@@ -1610,7 +1610,7 @@ Switch to hyphenation mode
 .REQ .hym n
 Set the hyphenation margin to
 .I n
-(default scale indicator\~\c
+(default scaling indicator\~\c
 .scaleindicator m ).
 .
 .REQ .hys n
@@ -1647,7 +1647,7 @@ Change to previous indent value.
 .REQ .in \[+-]N
 Change indent according to
 .I \[+-]N
-(default scale indicator\~\c
+(default scaling indicator\~\c
 .scaleindicator m ).
 .
 .REQ .it N trap
@@ -1710,7 +1710,7 @@ Set line length according to
 .I \[+-]N
 (default size
 .scalednumber 6.5 i ,
-default scale indicator\~\c
+default scaling indicator\~\c
 .scaleindicator m ).
 .
 .REQ .ls
@@ -1724,7 +1724,7 @@ i.e.,
 blank lines are inserted after each text output line.
 .
 .REQ .lt \[+-]N
-Length of title (default scale indicator\~\c
+Length of title (default scaling indicator\~\c
 .scaleindicator m ).
 .
 .REQ .mc
@@ -1740,7 +1740,7 @@ Set margin character to
 .I c
 and distance to
 .I N
-from right margin (default scale indicator\~\c
+from right margin (default scaling indicator\~\c
 .scaleindicator m ).
 .
 .REQ .mk register
@@ -1761,7 +1761,7 @@ Need a one-line vertical space.
 .REQ .ne N
 Need
 .I N
-vertical space (default scale indicator\~\c
+vertical space (default scaling indicator\~\c
 .scaleindicator v ).
 .
 .REQ .nf
@@ -1850,7 +1850,7 @@ The current page length is stored in
 .REQ .pl \[+-]N
 Change page length to
 .I \[+-]N
-(default scale indicator\~\c
+(default scaling indicator\~\c
 .scaleindicator v ).
 .
 .REQ .pm
@@ -1903,7 +1903,7 @@ Change to previous post-vertical line spacing.
 .REQ .pvs \[+-]N
 Change post-vertical line spacing according to
 .I \[+-]N
-(default scale indicator\~\c
+(default scaling indicator\~\c
 .scaleindicator p ).
 .
 .REQ .rchar c1 c2 .\|.\|.\&
@@ -1949,7 +1949,7 @@ Restore spacing; turn no-space mode off.
 .REQ .rt \[+-]N
 Return
 .I (upward only)
-to marked vertical place (default scale indicator\~\c
+to marked vertical place (default scaling indicator\~\c
 .scaleindicator v ).
 .
 .REQ .shc
@@ -1993,6 +1993,15 @@ Fonts
 etc.\& are special and will be searched for characters not in the
 current font.
 .
+.REQ .spreadwarn
+Toggle the spread warning on and off without changing its value.
+.
+.REQ .spreadwarn limit
+Emit a warning if each space in an output line is widened by
+.I limit
+or more (default scaling indicator\~\c
+.scaleindicator m ).
+.
 .REQ .ss N
 Space-character size set to
 .IR N /12
@@ -2162,7 +2171,7 @@ Change to previous vertical base line spacing.
 .REQ .vs \[+-]N
 Set vertical base line spacing according to
 .I \[+-]N
-(default scale indicator\~\c
+(default scaling indicator\~\c
 .scaleindicator p ).
 Default value is
 .scalednumber 12 p .
@@ -2171,6 +2180,10 @@ Default value is
 Set warnings code to
 .IR n .
 .
+.REQ .warnscale si
+Set scaling indicator used in warnings to
+.IR si .
+.
 .REQ .wh N
 Remove (first) trap at position
 .IR N .
diff --git a/man/groff_diff.man b/man/groff_diff.man
index ca8168e2..c1e22e2f 100644
--- a/man/groff_diff.man
+++ b/man/groff_diff.man
@@ -3,7 +3,7 @@
 .ig
 groff_diff.man
 
-Last update : 15 Apr 2002
+Last update : 11 May 2002
 
 This file is part of groff, the GNU roff type-setting system.
 It is the source of the man-page groff_diff(7).
@@ -1913,6 +1913,36 @@ are special and will be searched for characters not in the current
 font.
 .
 .TP
+.BI .spreadwarn\  limit
+Make
+.B troff
+emit a warning if the additional space inserted for each space between
+words in an output line is larger or equal to
+.IR limit .
+.
+A negative value is changed to zero; no argument toggles the warning on
+and off without changing
+.IR limit .
+.
+The default scaling indicator is\~\c
+.BR m .
+.
+At startup,
+.B spreadwarn
+is deactivated, and
+.I limit
+is set to 3m.
+.
+For example,
+.B .spreadwarn\ 0.2m
+will cause a warning if
+.B troff
+must add 0.2m or more for each interword space in a line.
+.
+This request is active only if text is justified to both margins (using
+.BR .ad\ b ).
+.
+.TP
 .BI .sty\  n\ f
 Associate style\~\c
 .I f
@@ -2208,6 +2238,24 @@ If
 is not given, all warnings will be enabled.
 .
 .TP
+.BI .warnscale\  si
+Set the scaling indicator used in warnings to
+.IR si .
+.
+Valid values for
+.I si
+are
+.BR u ,
+.BR i ,
+.BR c ,
+.BR p ,
+and
+.BR P .
+.
+At startup, it is set to\~\c
+.BR i .
+.
+.TP
 .BI .while \ c\ anything
 While condition\~\c
 .I c
diff --git a/src/roff/troff/env.cc b/src/roff/troff/env.cc
index ede6b78c..2d677745 100644
--- a/src/roff/troff/env.cc
+++ b/src/roff/troff/env.cc
@@ -1884,7 +1884,7 @@ breakpoint *environment::choose_breakpoint()
   }
   if (best_bp) {
     if (!best_bp_fits)
-      warning(WARN_BREAK, "can't break line");
+      output_warning(WARN_BREAK, "can't break line");
     return best_bp;
   }
   return 0;
@@ -1970,6 +1970,14 @@ static void distribute_space(node *n, int nspaces, hunits desired_space,
   static int reverse = 0;
   if (force_reverse || reverse)
     n = node_list_reverse(n);
+  if (!force_reverse && nspaces > 0 && spread_limit >= 0
+      && desired_space.to_units() > 0) {
+    hunits em = curenv->get_size();
+    double Ems = (double)desired_space.to_units() / nspaces
+		 / (em.is_zero() ? hresolution : em.to_units());
+    if (Ems > spread_limit)
+      output_warning(WARN_BREAK, "spreading %1m per space", Ems);
+  }
   for (node *tem = n; tem; tem = tem->next)
     tem->spread_space(&nspaces, &desired_space);
   if (force_reverse || reverse)
@@ -2004,6 +2012,9 @@ void environment::possibly_break_line(int start_here, int forced)
     case ADJUST_BOTH:
       if (bp->nspaces != 0)
 	extra_space_width = target_text_length - bp->width;
+      else if (bp->width > 0 && target_text_length > 0
+	       && target_text_length > bp->width)
+	output_warning(WARN_BREAK, "cannot adjust line");
       break;
     case ADJUST_CENTER:
       saved_indent += (target_text_length - bp->width)/2;
diff --git a/src/roff/troff/env.h b/src/roff/troff/env.h
index c8aede6c..1c694916 100644
--- a/src/roff/troff/env.h
+++ b/src/roff/troff/env.h
@@ -356,6 +356,8 @@ void init_environments();
 void read_hyphen_file(const char *name);
 void title();
 
+extern double spread_limit;
+
 extern int break_flag;
 extern symbol default_family;
 extern int translate_space_to_dummy;
diff --git a/src/roff/troff/input.cc b/src/roff/troff/input.cc
index 6902de82..d3ff2ea3 100644
--- a/src/roff/troff/input.cc
+++ b/src/roff/troff/input.cc
@@ -122,6 +122,11 @@ int have_input = 0;		// whether \f, \H, \R, \s, or \S has
 int tcommand_flag = 0;
 int safer_flag = 1;		// safer by default
 
+double spread_limit = -3.0 - 1.0;	// negative means deactivated
+
+double warn_scale;
+char warn_scaling_indicator;
+
 search_path *mac_path = &safer_macro_path;
 
 static int get_copy(node**, int = 0);
@@ -5604,6 +5609,47 @@ void write_macro_request()
   skip_line();
 }
 
+void warnscale_request()
+{
+  if (has_arg()) {
+    char c = tok.ch();
+    if (c == 'u')
+      warn_scale = 1.0;
+    else if (c == 'i')
+      warn_scale = (double)units_per_inch;
+    else if (c == 'c')
+      warn_scale = (double)units_per_inch / 2.54;
+    else if (c == 'p')
+      warn_scale = (double)units_per_inch / 72.0;
+    else if (c == 'P')
+      warn_scale = (double)units_per_inch / 6.0;
+    else {
+      warning(WARN_SCALE,
+	      "invalid scaling indicator `%1', using `i' instead", c);
+      c = 'i';
+    }
+    warn_scaling_indicator = c;
+  }
+  skip_line();
+}
+
+void spreadwarn_request()
+{
+  hunits n;
+  if (has_arg() && get_hunits(&n, 'm')) {
+    if (n < 0)
+      n = 0;
+    hunits em = curenv->get_size();
+    spread_limit = (double)n.to_units()
+		   / (em.is_zero() ? hresolution : em.to_units());
+  }
+  else
+    spread_limit = -spread_limit - 1;	// no arg toggles on/off without
+					// changing value; we mirror at
+					// -0.5 to make zero a valid value
+  skip_line();
+}
+
 static void init_charset_table()
 {
   char buf[16];
@@ -6659,6 +6705,8 @@ int main(int argc, char **argv)
   vresolution = font::vert;
   sizescale = font::sizescale;
   tcommand_flag = font::tcommand;
+  warn_scale = (double)units_per_inch;
+  warn_scaling_indicator = 'i';
   if (!fflag && font::family != 0 && *font::family != '\0')
     default_family = symbol(font::family);
   font_size::init_size_table(font::sizes);
@@ -6877,6 +6925,8 @@ void init_input_requests()
 #endif /* not POPEN_MISSING */
   init_request("psbb", ps_bbox_request);
   init_request("defcolor", define_color);
+  init_request("warnscale", warnscale_request);
+  init_request("spreadwarn", spreadwarn_request);
   number_reg_dictionary.define("systat", new variable_reg(&system_status));
   number_reg_dictionary.define("slimit",
 			       new variable_reg(&input_stack::limit));
@@ -7151,7 +7201,7 @@ static void copy_mode_error(const char *format,
     error(format, arg1, arg2, arg3);
 }
 
-enum error_type { WARNING, ERROR, FATAL };
+enum error_type { WARNING, OUTPUT_WARNING, ERROR, FATAL };
 
 static void do_error(error_type type,
 		     const char *format,
@@ -7180,6 +7230,18 @@ static void do_error(error_type type,
   case WARNING:
     fputs("warning: ", stderr);
     break;
+  case OUTPUT_WARNING:
+    double fromtop = topdiv->get_vertical_position().to_units() / warn_scale;
+    fprintf(stderr, "warning [p %d, %.1f%c",
+	    topdiv->get_page_number(), fromtop, warn_scaling_indicator);
+    if (topdiv != curdiv) {
+      double fromtop1 = curdiv->get_vertical_position().to_units()
+			/ warn_scale;
+      fprintf(stderr, ", div `%s', %.1f%c",
+	      curdiv->get_diversion_name(), fromtop1, warn_scaling_indicator);
+    }
+    fprintf(stderr, "]: ");
+    break;
   }
   errprint(format, arg1, arg2, arg3);
   fputc('\n', stderr);
@@ -7202,6 +7264,20 @@ int warning(warning_type t,
     return 0;
 }
 
+int output_warning(warning_type t,
+		   const char *format,
+		   const errarg &arg1,
+		   const errarg &arg2,
+		   const errarg &arg3)
+{
+  if ((t & warning_mask) != 0) {
+    do_error(OUTPUT_WARNING, format, arg1, arg2, arg3);
+    return 1;
+  }
+  else
+    return 0;
+}
+
 void error(const char *format,
 	   const errarg &arg1,
 	   const errarg &arg2,
diff --git a/src/roff/troff/troff.h b/src/roff/troff/troff.h
index 48e72a6e..e37137e0 100644
--- a/src/roff/troff/troff.h
+++ b/src/roff/troff/troff.h
@@ -1,5 +1,5 @@
 // -*- C++ -*-
-/* Copyright (C) 1989, 1990, 1991, 1992, 2000, 2001
+/* Copyright (C) 1989, 1990, 1991, 1992, 2000, 2001, 2002
    Free Software Foundation, Inc.
      Written by James Clark (jjc@jclark.com)
 
@@ -88,3 +88,7 @@ int warning(warning_type, const char *,
 	    const errarg & = empty_errarg,
 	    const errarg & = empty_errarg,
 	    const errarg & = empty_errarg);
+int output_warning(warning_type, const char *,
+		   const errarg & = empty_errarg,
+		   const errarg & = empty_errarg,
+		   const errarg & = empty_errarg);