Initial, still somewhat experimental implementation to leverage

less(1) -T and :t ctags(1)-like functionality to jump to the
definitions of various terms inside manual pages.
To be polished in the tree, so bear with me and report issues.

Technically, if less(1) is used as a pager, information is collected
by the mdoc(7) terminal formatter, first stored using the ohash
library, then ultimately written to a temporary file which is passed
to less via -T.  No change intended for other output formatters or
when running without a pager.

Based on an idea from Kristaps using feedback from many, in particular
phessler@ nicm@ millert@ halex@ doug@ kspillner@ deraadt@.

1 files changed, 21 insertions, 1 deletions

diff --git a/mdoc_term.c b/mdoc_term.c
index a2ce71fc..95790806 100644
--- a/mdoc_term.c
+++ b/mdoc_term.c
@@ -34,6 +34,7 @@
 #include "mdoc.h"
 #include "out.h"
 #include "term.h"
+#include "tag.h"
 #include "main.h"
 
 struct	termpair {
@@ -117,6 +118,7 @@ static	int	  termp_skip_pre(DECL_ARGS);
 static	int	  termp_sm_pre(DECL_ARGS);
 static	int	  termp_sp_pre(DECL_ARGS);
 static	int	  termp_ss_pre(DECL_ARGS);
+static	int	  termp_tag_pre(DECL_ARGS);
 static	int	  termp_under_pre(DECL_ARGS);
 static	int	  termp_ud_pre(DECL_ARGS);
 static	int	  termp_vt_pre(DECL_ARGS);
@@ -145,7 +147,7 @@ static	const struct termact termacts[MDOC_MAX] = {
 	{ termp_bold_pre, NULL }, /* Cm */
 	{ NULL, NULL }, /* Dv */
 	{ NULL, NULL }, /* Er */
-	{ NULL, NULL }, /* Ev */
+	{ termp_tag_pre, NULL }, /* Ev */
 	{ termp_ex_pre, NULL }, /* Ex */
 	{ termp_fa_pre, NULL }, /* Fa */
 	{ termp_fd_pre, termp_fd_post }, /* Fd */
@@ -1049,6 +1051,7 @@ static int
 termp_fl_pre(DECL_ARGS)
 {
 
+	termp_tag_pre(p, pair, meta, n);
 	term_fontpush(p, TERMFONT_BOLD);
 	term_word(p, "\\-");
 
@@ -1330,6 +1333,7 @@ static int
 termp_bold_pre(DECL_ARGS)
 {
 
+	termp_tag_pre(p, pair, meta, n);
 	term_fontpush(p, TERMFONT_BOLD);
 	return(1);
 }
@@ -2252,3 +2256,19 @@ termp_under_pre(DECL_ARGS)
 	term_fontpush(p, TERMFONT_UNDER);
 	return(1);
 }
+
+static int
+termp_tag_pre(DECL_ARGS)
+{
+
+	if (n->child != NULL &&
+	    n->child->type == ROFFT_TEXT &&
+	    n->prev == NULL &&
+	    (n->parent->tok == MDOC_It ||
+	     (n->parent->tok == MDOC_Xo &&
+	      n->parent->parent->prev == NULL &&
+	      n->parent->parent->parent->tok == MDOC_It)) &&
+	    ! tag_get(n->child->string, 0))
+		tag_put(n->child->string, 0, p->line);
+	return(1);
+}