+ [(yylsp@{b4_subtract([$2], [$1])@})])
+
+
+## ------------------ ##
+## Parser variables. ##
+## ------------------ ##
+
+# b4_declare_scanner_communication_variables
+# ------------------------------------------
+# Declare the variables that are global, or local to YYPARSE if
+# pure-parser.
+m4_define([b4_declare_scanner_communication_variables], [[
+/* The lookahead symbol. */
+int yychar;
+
+/* The semantic value of the lookahead symbol. */
+YYSTYPE yylval;]b4_locations_if([[
+
+/* Location data for the lookahead symbol. */
+YYLTYPE yylloc;]])b4_pure_if([], [[
+
+/* Number of syntax errors so far. */
+int yynerrs;]])])
+
+
+# b4_declare_parser_state_variables
+# ---------------------------------
+# Declare all the variables that are needed to maintain the parser state
+# between calls to yypush_parse.
+m4_define([b4_declare_parser_state_variables], [b4_pure_if([[
+ /* Number of syntax errors so far. */
+ int yynerrs;
+]])[
+ int yystate;
+ /* Number of tokens to shift before error messages enabled. */
+ int yyerrstatus;
+
+ /* The stacks and their tools:
+ `yyss': related to states.
+ `yyvs': related to semantic values.]b4_locations_if([[
+ `yyls': related to locations.]])[
+
+ Refer to the stacks thru separate pointers, to allow yyoverflow
+ to reallocate them elsewhere. */
+
+ /* The state stack. */
+ yytype_int16 yyssa[YYINITDEPTH];
+ yytype_int16 *yyss;
+ yytype_int16 *yyssp;
+
+ /* The semantic value stack. */
+ YYSTYPE yyvsa[YYINITDEPTH];
+ YYSTYPE *yyvs;
+ YYSTYPE *yyvsp;]b4_locations_if([[