Replace %push-parser' and %push-pull-parser' with

`%define push_pull "push"' and `%define push_pull "both"'.
`%define push_pull "pull"' is the default.
* doc/bison.texinfo (Push Decl, Push Parser Function,
Pull Parser Function, Parser Create Function, Parser Delete Function):
Update declarations.
(Decl Summary, Table of Symbols): Replace %push-parser and
%push-pull-parser entries with a %define push_pull entry.
* data/bison.m4 (b4_percent_define_check_values): New macro.
(b4_pull_if, b4_push_if, b4_use_push_for_pull_if): Move these
definitions...
* data/c.m4 (b4_identification): ... and the YYPUSH and YYPULL cpp
definitions...
* data/push.c: ... to here and compute them from the value of the
%define variable push_pull.
* data/c-skel.m4: Instead of choosing the push.c skeleton for push
parsing requests here...
* data/yacc.c: ... hack this to switch to push.c any time
b4_use_push_pull_flag or the %define variable push_pull is set.  This
will go away when we mv push.c yacc.c.
* data/c++-skel.m4, data/glr.c, data/java-skel.m4: Don't report that
push parsing is not supported since unused %define variables are
reported anyway.
* src/getargs.c, src/getargs.h (pull_parser, push_parser): Remove.
* src/muscle_tab.h (muscle_percent_define_check_values): Update
comments for consistency with b4_percent_define_check_values.
* src/output.c (prepare): Don't insert b4_pull_flag and b4_push_flag
muscles.
* src/parse-gram.y (PERCENT_PUSH_PARSER, PERCENT_PUSH_PULL_PARSER):
Remove.
(prologue_declaration): Remove %push-parser and %push-pull-parser
rules.
* src/scan-gram.l (%push-parser, %push-pull-parser): Remove rules.
* tests/calc.at: Update declarations.
* tests/input.at (%define enum variables): New test case.
* tests/push.at (Push Parsing: Memory Leak for Early Deletion): Update
declaration.
(Push Parsing: Multiple impure instances): Update declaration.
(Push Parsing: Unsupported Skeletons): New test case.
* tests/torture.at (Exploding the Stack Size with Alloca): Update
declaration.
(Exploding the Stack Size with Malloc): Update declaration.

data/bison.m4

@@ -214,13 +214,7 @@ b4_define_flag_if([error_verbose])	# Whether error are verbose.
 b4_define_flag_if([glr])		# Whether a GLR parser is requested.
 b4_define_flag_if([locations])	        # Whether locations are tracked.
 b4_define_flag_if([nondeterministic])	# Whether conflicts should be handled.
-b4_define_flag_if([pull])	        # Whether pull parsing is requested.
 b4_define_flag_if([pure])	        # Whether the interface is pure.
-b4_define_flag_if([push])	        # Whether push parsing is requested.
-b4_define_flag_if([use_push_for_pull])  # Whether push parsing should be used
-                                        # in place of pull parsing (where
-                                        # available) for the sake of the test
-                                        # suite.
 b4_define_flag_if([yacc])	        # Whether POSIX Yacc is emulated.
 
 
@@ -403,6 +397,43 @@ m4_define([b4_percent_define_default],
             m4_define([b4_percent_define_loc(]$1[)],
                       [[[[[Bison:b4_percent_define_default]:0.0]], [[[Bison:b4_percent_define_default]:0.0]]]])])])
 
+# b4_percent_define_check_values(VALUES)
+# --------------------------------------
+# Mimic muscle_percent_define_check_values in ../src/muscle_tab.h exactly
+# except that the VALUES structure is more appropriate for M4.  That is, VALUES
+# is a list of sublists of strings.  For each sublist, the first string is the
+# name of a %define variable, and all remaining strings in that sublist are the
+# valid values for that variable.  Complain if such a variable is undefined (a
+# Bison error since the default value should have been set already) or defined
+# to any other value (possibly a user error).  Don't record this as a Bison
+# usage of the variable as there's no reason to suspect that the value has yet
+# influenced the output.
+#
+# For example:
+#
+#   b4_percent_define_check_values([[[[foo]], [[foo-value1]], [[foo-value2]]]],
+#                                  [[[[bar]], [[bar-value1]]]])
+m4_define([b4_percent_define_check_values],
+[m4_foreach([b4_sublist], m4_quote($@),
+            [_b4_percent_define_check_values(b4_sublist)])])
+
+m4_define([_b4_percent_define_check_values],
+[m4_ifdef([b4_percent_define(]$1[)],
+  [m4_pushdef([b4_good_value], [0])dnl
+   m4_if($#, 1, [],
+         [m4_foreach([b4_value], m4_dquote(m4_shift($@)),
+                     [m4_if(m4_indir([b4_percent_define(]$1[)]), b4_value,
+                            [m4_define([b4_good_value], [1])])])])dnl
+   m4_if(b4_good_value, [0],
+         [m4_pushdef([b4_loc], m4_indir([b4_percent_define_loc(]$1[)]))dnl
+          b4_complain_at(b4_loc,
+                         [[invalid value for %%define variable `%s': `%s']],
+                         [$1],
+                         m4_dquote(m4_indir([b4_percent_define(]$1[)])))dnl
+          m4_popdef([b4_loc])])dnl
+   m4_popdef([b4_good_value])],
+  [b4_fatal([[undefined %%define variable `%s' passed to b4_percent_define_check_values]], [$1])])])
+
 # b4_percent_code_get([QUALIFIER])
 # --------------------------------
 # If any %code blocks for QUALIFIER are defined, emit them beginning with a

data/c++-skel.m4

@@ -19,8 +19,6 @@
 b4_glr_if(             [m4_define([b4_used_skeleton], [b4_pkgdatadir/[glr.cc]])])
 b4_nondeterministic_if([m4_define([b4_used_skeleton], [b4_pkgdatadir/[glr.cc]])])
 
-b4_push_if([b4_complain([[C++ push parsers are not supported]])])
-
 m4_define_default([b4_used_skeleton], [b4_pkgdatadir/[lalr1.cc]])
 m4_define_default([b4_skeleton], ["b4_basename(b4_used_skeleton)"])
 

data/c-skel.m4

@@ -16,7 +16,6 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-b4_push_if(            [m4_define([b4_used_skeleton], [b4_pkgdatadir/[push.c]])])
 b4_glr_if(             [m4_define([b4_used_skeleton], [b4_pkgdatadir/[glr.c]])])
 b4_nondeterministic_if([m4_define([b4_used_skeleton], [b4_pkgdatadir/[glr.c]])])
 

data/c.m4

@@ -41,12 +41,6 @@ m4_define([b4_identification],
 /* Pure parsers.  */
 [#]define YYPURE b4_pure_flag
 
-/* Push parsers.  */
-[#]define YYPUSH b4_push_flag
-
-/* Pull parsers.  */
-[#]define YYPULL b4_pull_flag
-
 /* Using locations.  */
 [#]define YYLSP_NEEDED b4_locations_flag
 ])

data/glr.c

@@ -20,9 +20,6 @@
 
 m4_include(b4_pkgdatadir/[c.m4])
 
-b4_push_if([
-b4_complain([[non-deterministic push parsers are not yet supported]])])
-
 ## ---------------- ##
 ## Default values.  ##
 ## ---------------- ##

data/java-skel.m4

@@ -18,7 +18,6 @@
 
 b4_glr_if(             [b4_complain([%%glr-parser not supported for Java])])
 b4_nondeterministic_if([b4_complain([%%nondeterministic-parser not supported for Java])])
-b4_push_if(            [b4_complain([%%push-parser is not supported for Java])])
 
 m4_define_default([b4_used_skeleton], [b4_pkgdatadir/[lalr1.java]])
 m4_define_default([b4_skeleton], ["b4_basename(b4_used_skeleton)"])

data/push.c

@@ -18,17 +18,22 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+# Check the value of %define push_pull.
+b4_percent_define_default([[push_pull]], [[pull]])
+b4_percent_define_check_values([[[[push_pull]], [[pull]], [[push]], [[both]]]])
+b4_define_flag_if([pull]) m4_define([b4_pull_flag], [[1]])
+b4_define_flag_if([push]) m4_define([b4_push_flag], [[1]])
+m4_case(b4_percent_define_get([[push_pull]]),
+        [pull], [m4_define([b4_push_flag], [[0]])],
+        [push], [m4_define([b4_pull_flag], [[0]])])
+
 # Handle BISON_USE_PUSH_FOR_PULL for the test suite.  So that push parsing
 # tests function as written, don't let BISON_USE_PUSH_FOR_PULL modify Bison's
 # behavior at all when push parsing is already requested.
+b4_define_flag_if([use_push_for_pull])
 b4_use_push_for_pull_if([
-  b4_push_if([
-    m4_define([b4_use_push_for_pull_flag], [[0]])
-    b4_define_flag_if([use_push_for_pull])
-  ], [
-    m4_define([b4_push_flag], [[1]])
-    b4_define_flag_if([push])
-  ])])
+  b4_push_if([m4_define([b4_use_push_for_pull_flag], [[0]])],
+             [m4_define([b4_push_flag], [[1]])])])
 
 m4_include(b4_pkgdatadir/[c.m4])
 
@@ -157,8 +162,14 @@ b4_copyright([Skeleton implementation for Bison's Yacc-like parsers in C],dnl '
    define necessary library symbols; they are noted "INFRINGES ON
    USER NAME SPACE" below.  */
 
-]b4_identification
-b4_percent_code_get([[top]])[]dnl
+]b4_identification[
+/* Push parsers.  */
+#define YYPUSH ]b4_push_flag[
+
+/* Pull parsers.  */
+#define YYPULL ]b4_pull_flag[
+
+]b4_percent_code_get([[top]])[]dnl
 m4_if(b4_prefix, [yy], [],
 [[/* Substitute the variable and function names.  */
 ]b4_pull_if([[#define yyparse         ]b4_prefix[parse

data/yacc.c

@@ -18,8 +18,9 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-# Handle BISON_USE_PUSH_FOR_PULL for the test suite.
-b4_use_push_for_pull_if([m4_include(b4_pkgdatadir/[push.c])], [
+# This hack will go away when we mv push.c yacc.c.
+m4_ifndef([b4_percent_define(push_pull)],
+[m4_if(b4_use_push_for_pull_flag, [0], [
 
 m4_include(b4_pkgdatadir/[c.m4])
 
@@ -1532,4 +1533,6 @@ b4_percent_code_get([[provides]])
 ])dnl b4_defines_if
 m4_divert_pop(0)
 
-])dnl b4_use_push_for_pull_if
+],
+[m4_include(b4_pkgdatadir/[push.c])])],
+[m4_include(b4_pkgdatadir/[push.c])])