m4: use a safer pattern to enable/disable output

[bison.git] / data / yacc.c

diff --git a/data/yacc.c b/data/yacc.c
index bbc9d91545b11d6ffebbd1df5ab300213bb595cc..810e2b21a0726c8544433e37a1160c6adf477c93 100644 (file)
--- a/data/yacc.c
+++ b/data/yacc.c
@@ -65,24 +65,36 @@ m4_define_default([b4_stack_depth_init],  [200])
 ## ------------------------ ##
 
 b4_percent_define_default([[api.pure]], [[false]])
-b4_define_flag_if([pure])
-m4_define([b4_pure_flag],
-          [b4_percent_define_flag_if([[api.pure]], [[1]], [[0]])])
-
-# b4_yacc_pure_if(IF-TRUE, IF-FALSE)
-# ----------------------------------
-# Expand IF-TRUE, if %pure-parser and %parse-param, IF-FALSE otherwise.
-m4_define([b4_yacc_pure_if],
-[b4_pure_if([m4_ifset([b4_parse_param],
-                     [$1], [$2])],
-           [$2])])
-
+b4_percent_define_check_values([[[[api.pure]],
+                                 [[false]], [[true]], [[]], [[full]]]])
+
+m4_define([b4_pure_flag], [[0]])
+m4_case(b4_percent_define_get([[api.pure]]),
+        [false], [m4_define([b4_pure_flag], [[0]])],
+        [true],  [m4_define([b4_pure_flag], [[1]])],
+        [],      [m4_define([b4_pure_flag], [[1]])],
+        [full],  [m4_define([b4_pure_flag], [[2]])])
+
+m4_define([b4_pure_if],
+[m4_case(b4_pure_flag,
+         [0], [$2],
+         [1], [$1],
+         [2], [$1])])
+         [m4_fatal([invalid api.pure value: ]$1)])])
+
+# b4_yyerror_arg_loc_if(ARG)
+# --------------------------
+# Expand ARG iff yyerror is to be given a location as argument.
+m4_define([b4_yyerror_arg_loc_if],
+[b4_locations_if([m4_case(b4_pure_flag,
+                          [1], [m4_ifset([b4_parse_param], [$1])],
+                          [2], [$1])])])
 
 # b4_yyerror_args
 # ---------------
 # Arguments passed to yyerror: user args plus yylloc.
 m4_define([b4_yyerror_args],
-[b4_yacc_pure_if([b4_locations_if([&yylloc, ])])dnl
+[b4_yyerror_arg_loc_if([&yylloc, ])dnl
 m4_ifset([b4_parse_param], [b4_c_args(b4_parse_param), ])])
 
 
@@ -314,14 +326,12 @@ m4_define([b4_shared_declarations],
 ]b4_cpp_guard_close([b4_spec_defines_file])[]dnl
 ])
 
+
 ## -------------- ##
 ## Output files.  ##
 ## -------------- ##
 
-# We do want M4 expansion after # for CPP macros.
-m4_changecom()
-m4_divert_push(0)dnl
-@output(b4_parser_file_name@)@
+b4_output_begin([b4_parser_file_name])
 b4_copyright([Bison implementation for Yacc-like parsers in C],
              [1984, 1989-1990, 2000-2012])[
 
@@ -2040,11 +2050,13 @@ yypushreturn:]])[
 
 
 ]b4_epilogue[]dnl
+b4_output_end()
+
 b4_defines_if(
-[@output(b4_spec_defines_file@)@
-b4_copyright([Bison interface for Yacc-like parsers in C],
-             [1984, 1989-1990, 2000-2012])[
+[b4_output_begin([b4_spec_defines_file])[
+]b4_copyright([Bison interface for Yacc-like parsers in C],
+              [1984, 1989-1990, 2000-2012])[
 
 ]b4_shared_declarations[
-]])dnl b4_defines_if
-m4_divert_pop(0)
+]b4_output_end()
+])