vis: display lua search paths in :help output

vis-cmds.c

@@ -1,6 +1,7 @@
 /* this file is included from sam.c */
 
 #include <termkey.h>
+#include "vis-lua.h"
 
 #ifndef VIS_OPEN
 #define VIS_OPEN "vis-open"
@@ -659,6 +660,20 @@ static bool cmd_help(Vis *vis, Win *win, Command *cmd, const char *argv[], Curso
 		"(prefix with C-, S-, and M- for Ctrl, Shift and Alt respectively)\n\n");
 	print_symbolic_keys(vis, txt);
 
+	const char *paths = vis_lua_paths_get(vis);
+	if (paths) {
+		char *copy = strdup(paths);
+		text_appendf(txt, "\n Lua paths used to load runtime files "
+			"(? will be replaced by filename):\n\n");
+		for (char *elem = copy, *next; elem; elem = next) {
+			if ((next = strstr(elem, ";")))
+				*next++ = '\0';
+			if (*elem)
+				text_appendf(txt, "  %s\n", elem);
+		}
+		free (copy);
+	}
+
 	text_save(txt, NULL);
 	return true;
 }

vis-lua.c

@@ -17,6 +17,8 @@
 
 #if !CONFIG_LUA
 
+bool vis_lua_path_add(Vis *vis, const char *path) { return true; }
+const char *vis_lua_paths_get(Vis *vis) { return NULL; }
 void vis_lua_init(Vis *vis) { }
 void vis_lua_start(Vis *vis) { }
 void vis_lua_quit(Vis *vis) { }
@@ -1033,7 +1035,7 @@ static bool vis_lua_path_strip(Vis *vis) {
 	return true;
 }
 
-static bool vis_lua_path_add(Vis *vis, const char *path) {
+bool vis_lua_path_add(Vis *vis, const char *path) {
 	if (!path)
 		return false;
 	lua_State *L = vis->lua;
@@ -1049,6 +1051,15 @@ static bool vis_lua_path_add(Vis *vis, const char *path) {
 	return true;
 }
 
+const char *vis_lua_paths_get(Vis *vis) {
+	lua_State *L = vis->lua;
+	if (!L)
+		return NULL;
+	lua_getglobal(L, "package");
+	lua_getfield(L, -1, "path");
+	return lua_tostring(L, -1);
+}
+
 void vis_lua_init(Vis *vis) {
 	lua_State *L = luaL_newstate();
 	if (!L)

vis-lua.h

@@ -11,6 +11,12 @@ typedef struct lua_State lua_State;
 
 #include "vis.h"
 
+/* add a directory to consider when loading lua files */
+bool vis_lua_path_add(Vis*, const char *path);
+/* get semi colon separated list of paths to load lua files */
+const char *vis_lua_paths_get(Vis*);
+
+/* various event handlers, triggered by the vis core */
 void vis_lua_init(Vis*);
 void vis_lua_start(Vis*);
 void vis_lua_quit(Vis*);