[PATCH] %define boolean variables

[Paolo Bonzini]

> As a compromise, if you keep the current behavior of empty being true, 
> and `%define FOO' aliasing `%define FOO ""', it's ok for me to complain 
> on anything but empty/"true"/"false", including making "0" or "1" invalid.

Here's my concrete proposal.

Paolo

2007-01-29  Paolo Bonzini  <address@hidden>

        * data/bison.m4 (b4_percent_define_flag_if): Don't treat 0 as false.
        Complain if the value does not match empty, "true" or "false".
        * data/c++.m4: Adjust default definitions of %define variables.
        * data/java.m4: Adjust default definitions of %define variables.
        * doc/bison.texinfo (%define): Adjust according to above behavior.
        * tests/input.at (Boolean %define variables): Test new behavior.

Index: data/bison.m4
===================================================================
RCS file: /sources/bison/bison/data/bison.m4,v
retrieving revision 1.15
diff -u -r1.15 bison.m4
--- data/bison.m4       23 Jan 2007 12:24:27 -0000      1.15
+++ data/bison.m4       29 Jan 2007 12:15:58 -0000
@@ -369,8 +369,10 @@
 m4_define([b4_percent_define_flag_if],
 [b4_percent_define_ifdef([$1],
                         [m4_case(b4_percent_define_get([$1]),
-                                 [0], [$3], [false], [$3],
-                                 [$2])],
+                                 [], [$2], [true], [$2], [false], [$3],
+                                 [m4_expand_once(
+                                  [b4_complain([[invalid value for %%define 
variable `%s']], [$1])],
+                                  [[b4_percent_define_flag_if($1)]])])],
                         [m4_fatal([invalid %define variable passed to 
b4_percent_define_flag_if: ]$1)])])
 
 # b4_percent_define_default(VARIABLE, DEFAULT)
Index: data/c++.m4
===================================================================
RCS file: /sources/bison/bison/data/c++.m4,v
retrieving revision 1.14
diff -u -r1.14 c++.m4
--- data/c++.m4 23 Jan 2007 12:24:27 -0000      1.14
+++ data/c++.m4 29 Jan 2007 12:15:58 -0000
@@ -31,10 +31,10 @@
 b4_percent_define_default([[location_type]], [[location]])
 b4_percent_define_default([[filename_type]], [[std::string]])
 b4_percent_define_default([[namespace]], m4_defn([b4_prefix]))
-b4_percent_define_default([[global_tokens_and_yystype]], [[0]])
+b4_percent_define_default([[global_tokens_and_yystype]], [[false]])
 b4_percent_define_default([[define_location_comparison]],
                           [m4_if(b4_percent_define_get([[filename_type]]),
-                                 [std::string], [[1]], [[0]])])
+                                 [std::string], [[true]], [[false]])])
 
 
 # b4_token_enums(LIST-OF-PAIRS-TOKEN-NAME-TOKEN-NUMBER)
Index: data/java.m4
===================================================================
RCS file: /sources/bison/bison/data/java.m4,v
retrieving revision 1.1
diff -u -r1.1 java.m4
--- data/java.m4        29 Jan 2007 10:54:42 -0000      1.1
+++ data/java.m4        29 Jan 2007 12:15:58 -0000
@@ -34,13 +34,13 @@
 
 # b4_public_if(TRUE, FALSE)
 # -------------------------
-b4_percent_define_default([public], 0)
+b4_percent_define_default([public], [false])
 m4_define([b4_public_if],
 [b4_percent_define_flag_if([public], [$1], [$2])])
 
 # b4_single_class_if(TRUE, FALSE)
 # -------------------------------
-b4_percent_define_default([single_class], 0)
+b4_percent_define_default([single_class], [false])
 m4_define([b4_single_class_if],
 [b4_percent_define_flag_if([single_class], [$1], [$2])])
 
Index: doc/bison.texinfo
===================================================================
RCS file: /sources/bison/bison/doc/bison.texinfo,v
retrieving revision 1.225
diff -u -r1.225 bison.texinfo
--- doc/bison.texinfo   29 Jan 2007 10:54:42 -0000      1.225
+++ doc/bison.texinfo   29 Jan 2007 12:15:59 -0000
@@ -4696,10 +4696,10 @@
 Define a variable to adjust Bison's behavior.
 The list of available variables and their meanings depends on the selected
 target language and/or the parser skeleton (@pxref{Decl Summary,,%language}).
-The @var{value} can be omitted for boolean variables; for
-boolean variables, the skeletons will treat a @var{value} of @samp{0}
-or @samp{false} as the boolean variable being false, and anything else
-as true.
+Some @var{define-variable}s may be used as boolean values: in this case,
+the skeleton will conventionally treat a @var{value} of @samp{false}
+as the boolean variable being false; a value of @samp{true}, or @var{value}
+being omitted altogether, will conversely define the variable as true.
 @end deffn
 
 @deffn {Directive} %defines
Index: tests/input.at
===================================================================
RCS file: /sources/bison/bison/tests/input.at,v
retrieving revision 1.76
diff -u -r1.76 input.at
--- tests/input.at      29 Jan 2007 10:54:42 -0000      1.76
+++ tests/input.at      29 Jan 2007 12:15:59 -0000
@@ -820,3 +820,23 @@
 ]])
 
 AT_CLEANUP
+
+## --------------------------- ##
+## Boolean %define variables.  ##
+## --------------------------- ##
+
+AT_SETUP([Boolean %define variables])
+
+AT_DATA([Input.y],
+[[%language "Java"
+%define public "maybe"
+%define parser_class_name "Input"
+%%
+start: ;
+]])
+
+AT_CHECK([[bison Input.y]], [1], [],
+[[Input.y: invalid value for %define variable `public'
+]])
+
+AT_CLEANUP