Implement a leading spaces macro request, `lsm', in analogy to

`blm'.
Implement two new number registers, \n[lsn] and \n[lss], which hold
the number of spaces and the horizontal space, respectively, which
would be inserted if the macro registered by `lsm' wasn't called.

* src/roff/troff/input.cpp (leading_spaces_macro_name,
leading_spaces_number, leading_spaces_space): New global
variables.
(leading_spaces_macro): New function.
(process_input_stack) <token::TOKEN_SPACE>: Handle `lsm'.
(init_input_requests): Register `lsm', \n[lsn], and \n[lss].

* NEWS, man/groff_diff.man, man/groff.man, doc/groff.texinfo
(Leading Spaces Traps): Document new requests and registers.

1 files changed, 26 insertions, 6 deletions

diff --git a/src/roff/troff/input.cpp b/src/roff/troff/input.cpp
index 8038f70f..b3243f5a 100644
--- a/src/roff/troff/input.cpp
+++ b/src/roff/troff/input.cpp
@@ -101,6 +101,7 @@ static void disable_warning(const char *);
 static int escape_char = '\\';
 static symbol end_macro_name;
 static symbol blank_line_macro_name;
+static symbol leading_spaces_macro_name;
 static int compatible_flag = 0;
 int ascii_output_flag = 0;
 int suppress_output_flag = 0;
@@ -120,7 +121,7 @@ double spread_limit = -3.0 - 1.0;	// negative means deactivated
 
 double warn_scale;
 char warn_scaling_indicator;
-int debug_state = 0;            // turns on debugging of the html troff state
+int debug_state = 0;		// turns on debugging of the html troff state
 
 search_path *mac_path = &safer_macro_path;
 
@@ -2608,6 +2609,12 @@ void blank_line_macro()
   skip_line();
 }
 
+void leading_spaces_macro()
+{
+  leading_spaces_macro_name = get_name();
+  skip_line();
+}
+
 static void trapping_blank_line()
 {
   if (!blank_line_macro_name.is_null())
@@ -2773,6 +2780,9 @@ int hmotion_node::reread(int *)
   return 0;
 }
 
+static int leading_spaces_number = 0;
+static int leading_spaces_space = 0;
+
 void process_input_stack()
 {
   int_stack trap_bol_stack;
@@ -2853,11 +2863,12 @@ void process_input_stack()
 	    do {
 	      node *n;
 	      cc = get_copy(&n);
-	      if (cc != EOF)
+	      if (cc != EOF) {
 		if (cc != '\0')
 		  curdiv->transparent_output(transparent_translate(cc));
 		else
 		  curdiv->transparent_output(n);
+	      }
 	    } while (cc != '\n' && cc != EOF);
 	    if (cc == EOF)
 	      curdiv->transparent_output('\n');
@@ -2919,9 +2930,15 @@ void process_input_stack()
 	    trapping_blank_line();
 	  else {
 	    push_token(tok);
-	    curenv->do_break();
-	    curenv->add_node(new hmotion_node(space_width * nspaces,
-					      curenv->get_fill_color()));
+	    leading_spaces_number = nspaces;
+	    leading_spaces_space = space_width.to_units() * nspaces;
+	    if (!leading_spaces_macro_name.is_null())
+	      spring_trap(leading_spaces_macro_name);
+	    else {
+	      curenv->do_break();
+	      curenv->add_node(new hmotion_node(space_width * nspaces,
+						curenv->get_fill_color()));
+	    }
 	    bol = 0;
 	  }
 	}
@@ -4080,7 +4097,7 @@ void spring_trap(symbol nm)
     postponed_trap = nm;
     return;
   }
-  static char buf[2] = { BEGIN_TRAP, 0 };
+  static char buf[2] = { BEGIN_TRAP, '\0' };
   static char buf2[2] = { END_TRAP, '\0' };
   input_stack::push(make_temp_iterator(buf2));
   request_or_macro *p = lookup_request(nm);
@@ -7812,6 +7829,7 @@ void init_input_requests()
   init_request("ig", ignore);
   init_request("length", length_request);
   init_request("lf", line_file);
+  init_request("lsm", leading_spaces_macro);
   init_request("mso", macro_source);
   init_request("nop", nop_request);
   init_request("nroff", nroff_request);
@@ -7879,6 +7897,8 @@ void init_input_requests()
   number_reg_dictionary.define("c.", new writable_lineno_reg);
   number_reg_dictionary.define("llx", new variable_reg(&llx_reg_contents));
   number_reg_dictionary.define("lly", new variable_reg(&lly_reg_contents));
+  number_reg_dictionary.define("lsn", new variable_reg(&leading_spaces_number));
+  number_reg_dictionary.define("lss", new variable_reg(&leading_spaces_space));
   number_reg_dictionary.define("opmaxx",
 			       new variable_reg(&output_reg_maxx_contents));
   number_reg_dictionary.define("opmaxy",