X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/258cddbc3695f2095cbfbc9ff95309b28733f7d2..7d6bad195977b0204fc8406cac57cf5a4f1c769b:/data/bison.m4?ds=sidebyside

diff --git a/data/bison.m4 b/data/bison.m4
index a5c1ee73..704f172e 100644
--- a/data/bison.m4
+++ b/data/bison.m4
@@ -2,7 +2,7 @@
 
 # Language-independent M4 Macros for Bison.
 
-# Copyright (C) 2002, 2004-2012 Free Software Foundation, Inc.
+# Copyright (C) 2002, 2004-2013 Free Software Foundation, Inc.
 
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -22,14 +22,17 @@
 ## Identification.  ##
 ## ---------------- ##
 
-# b4_copyright(TITLE, YEARS)
-# --------------------------
+# b4_copyright(TITLE, [YEARS])
+# ----------------------------
+# If YEARS are not defined, use b4_copyright_years.
 m4_define([b4_copyright],
 [b4_comment([A Bison parser, made by GNU Bison b4_version.])
 
 b4_comment([$1
 
-m4_text_wrap([Copyright (C) $2 Free Software Foundation, Inc.], [   ])
+]m4_dquote(m4_text_wrap([Copyright (C)
+]m4_ifval([$2], [[$2]], [m4_defn([b4_copyright_years])])[
+Free Software Foundation, Inc.]))[
 
 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
@@ -58,6 +61,30 @@ This special exception was added by the Free Software Foundation in
 version 2.2 of Bison.])])
 
 
+## -------- ##
+## Output.  ##
+## -------- ##
+
+# b4_output_begin(FILE)
+# ---------------------
+# Enable output, i.e., send to diversion 0, expand after "#", and
+# generate the tag to output into FILE.  Must be followed by EOL.
+m4_define([b4_output_begin],
+[m4_changecom()
+m4_divert_push(0)dnl
+@output(m4_unquote([$1])@)@dnl
+])
+
+
+# b4_output_end()
+# ---------------
+# Output nothing, restore # as comment character (no expansions after #).
+m4_define([b4_output_end],
+[m4_divert_pop(0)
+m4_changecom([#])
+])
+
+
 ## ---------------- ##
 ## Error handling.  ##
 ## ---------------- ##
@@ -79,30 +106,16 @@ _m4eof
 ])dnl
 m4_if(m4_sysval, [0], [], [m4_fatal([$0: cannot write to stdout])])])
 
-# b4_error(KIND, FORMAT, [ARG1], [ARG2], ...)
-# -------------------------------------------
-# Write @KIND(FORMAT@,ARG1@,ARG2@,...@) to stdout.
+# b4_error(KIND, START, END, FORMAT, [ARG1], [ARG2], ...)
+# -------------------------------------------------------
+# Write @KIND(START@,END@,FORMAT@,ARG1@,ARG2@,...@) to stdout.
 #
 # For example:
 #
-#   b4_error([[warn]], [[invalid value for '%s': %s]], [[foo]], [[3]])
+#   b4_error([[complain]], [[input.y:2.3]], [[input.y:5.4]],
+#            [[invalid %s]], [[foo]])
 m4_define([b4_error],
-[b4_cat([[@]$1[(]$2[]]dnl
-[m4_if([$#], [2], [],
-       [m4_foreach([b4_arg],
-                   m4_dquote(m4_shift(m4_shift($@))),
-                   [[@,]b4_arg])])[@)]])])
-
-# b4_error_at(KIND, START, END, FORMAT, [ARG1], [ARG2], ...)
-# ----------------------------------------------------------
-# Write @KIND_at(START@,END@,FORMAT@,ARG1@,ARG2@,...@) to stdout.
-#
-# For example:
-#
-#   b4_error_at([[complain]], [[input.y:2.3]], [[input.y:5.4]],
-#               [[invalid %s]], [[foo]])
-m4_define([b4_error_at],
-[b4_cat([[@]$1[_at(]$2[@,]$3[@,]$4[]]dnl
+[b4_cat([[@complain][(]$1[@,]$2[@,]$3[@,]$4[]]dnl
 [m4_if([$#], [4], [],
        [m4_foreach([b4_arg],
                    m4_dquote(m4_shift(m4_shift(m4_shift(m4_shift($@))))),
@@ -122,21 +135,21 @@ m4_define([b4_error_at],
 #   m4_define([asdf], [ASDF])
 #   m4_define([fsa], [FSA])
 #   m4_define([fdsa], [FDSA])
-#   b4_warn([[[asdf), asdf]]], [[[fsa), fsa]]], [[[fdsa), fdsa]]])
-#   b4_warn([[asdf), asdf]], [[fsa), fsa]], [[fdsa), fdsa]])
-#   b4_warn()
-#   b4_warn(1)
-#   b4_warn(1, 2)
+#   b4_warn_at([[[asdf), asdf]]], [[[fsa), fsa]]], [[[fdsa), fdsa]]])
+#   b4_warn_at([[asdf), asdf]], [[fsa), fsa]], [[fdsa), fdsa]])
+#   b4_warn_at()
+#   b4_warn_at(1)
+#   b4_warn_at(1, 2)
 #
 # Should produce this without newlines:
 #
-#   @warn([asdf), asdf]@,[fsa), fsa]@,[fdsa), fdsa]@)
-#   @warn(asdf), asdf@,fsa), fsa@,fdsa), fdsa@)
+#   @warn_at([asdf), asdf]@,@,@,[fsa), fsa]@,[fdsa), fdsa]@)
+#   @warn(asdf), asdf@,@,@,fsa), fsa@,fdsa), fdsa@)
 #   @warn(@)
 #   @warn(1@)
 #   @warn(1@,2@)
 m4_define([b4_warn],
-[b4_error([[warn]], $@)])
+[b4_error([[warn]], [], [], $@)])
 
 # b4_warn_at(START, END, FORMAT, [ARG1], [ARG2], ...)
 # ---------------------------------------------------
@@ -146,15 +159,15 @@ m4_define([b4_warn],
 #
 #   b4_warn_at([[input.y:2.3]], [[input.y:5.4]], [[invalid %s]], [[foo]])
 m4_define([b4_warn_at],
-[b4_error_at([[warn]], $@)])
+[b4_error([[warn]], $@)])
 
 # b4_complain(FORMAT, [ARG1], [ARG2], ...)
 # ----------------------------------------
-# Write @complain(FORMAT@,ARG1@,ARG2@,...@) to stdout.
+# Bounce to b4_complain_at.
 #
 # See b4_warn example.
 m4_define([b4_complain],
-[b4_error([[complain]], $@)])
+[b4_error([[complain]], [], [], $@)])
 
 # b4_complain_at(START, END, FORMAT, [ARG1], [ARG2], ...)
 # -------------------------------------------------------
@@ -162,15 +175,15 @@ m4_define([b4_complain],
 #
 # See b4_warn_at example.
 m4_define([b4_complain_at],
-[b4_error_at([[complain]], $@)])
+[b4_error([[complain]], $@)])
 
 # b4_fatal(FORMAT, [ARG1], [ARG2], ...)
 # -------------------------------------
-# Write @fatal(FORMAT@,ARG1@,ARG2@,...@) to stdout and exit.
+# Bounce to b4_fatal_at.
 #
 # See b4_warn example.
 m4_define([b4_fatal],
-[b4_error([[fatal]], $@)dnl
+[b4_error([[fatal]], [], [], $@)dnl
 m4_exit(1)])
 
 # b4_fatal_at(START, END, FORMAT, [ARG1], [ARG2], ...)
@@ -179,25 +192,10 @@ m4_exit(1)])
 #
 # See b4_warn_at example.
 m4_define([b4_fatal_at],
-[b4_error_at([[fatal]], $@)dnl
+[b4_error([[fatal]], $@)dnl
 m4_exit(1)])
 
 
-## ---------------- ##
-## Default values.  ##
-## ---------------- ##
-
-# m4_define_default([b4_lex_param], [])   dnl breaks other skeletons
-m4_define_default([b4_pre_prologue], [])
-m4_define_default([b4_post_prologue], [])
-m4_define_default([b4_epilogue], [])
-m4_define_default([b4_parse_param], [])
-
-# The initial column and line.
-m4_define_default([b4_location_initial_column], [1])
-m4_define_default([b4_location_initial_line],   [1])
-
-
 ## ------------ ##
 ## Data Types.  ##
 ## ------------ ##
@@ -209,6 +207,87 @@ m4_define([b4_ints_in],
 [m4_eval([$3 <= $1 && $1 <= $4 && $3 <= $2 && $2 <= $4])])
 
 
+# b4_subtract(LHS, RHS)
+# ---------------------
+# Evaluate LHS - RHS if they are integer literals, otherwise expand
+# to (LHS) - (RHS).
+m4_define([b4_subtract],
+[m4_bmatch([$1$2], [^[0123456789]*$],
+           [m4_eval([$1 - $2])],
+           [($1) - ($2)])])
+
+# b4_join(ARG1, ...)
+# _b4_join(ARG1, ...)
+# -------------------
+# Join with comma, skipping empty arguments.
+# b4_join calls itself recursively until it sees the first non-empty
+# argument, then calls _b4_join which prepends each non-empty argument
+# with a comma.
+m4_define([b4_join],
+[m4_if([$#$1],
+       [1], [],
+       [m4_ifval([$1],
+                 [$1[]_$0(m4_shift($@))],
+                 [$0(m4_shift($@))])])])
+
+# _b4_join(ARGS1, ...)
+# --------------------
+m4_define([_b4_join],
+[m4_if([$#$1],
+       [1], [],
+       [m4_ifval([$1], [, $1])[]$0(m4_shift($@))])])
+
+
+
+
+# b4_integral_parser_tables_map(MACRO)
+# -------------------------------------
+# Map MACRO on all the integral tables.  MACRO is expected to have
+# the signature MACRO(TABLE-NAME, CONTENT, COMMENT).
+m4_define([b4_integral_parser_tables_map],
+[$1([pact], [b4_pact],
+    [[YYPACT[STATE-NUM] -- Index in YYTABLE of the portion describing
+STATE-NUM.]])
+
+$1([defact], [b4_defact],
+   [[YYDEFACT[STATE-NUM] -- Default reduction number in state STATE-NUM.
+Performed when YYTABLE does not specify something else to do.  Zero
+means the default is an error.]])
+
+$1([pgoto], [b4_pgoto], [[YYPGOTO[NTERM-NUM].]])
+
+$1([defgoto], [b4_defgoto], [[YYDEFGOTO[NTERM-NUM].]])
+
+$1([table], [b4_table],
+   [[YYTABLE[YYPACT[STATE-NUM]] -- What to do in state STATE-NUM.  If
+positive, shift that token.  If negative, reduce the rule whose
+number is the opposite.  If YYTABLE_NINF, syntax error.]])
+
+$1([check], [b4_check])
+
+$1([stos], [b4_stos],
+   [[YYSTOS[STATE-NUM] -- The (internal number of the) accessing
+symbol of state STATE-NUM.]])
+
+$1([r1], [b4_r1],
+   [[YYR1[YYN] -- Symbol number of symbol that rule YYN derives.]])
+
+$1([r2], [b4_r2],
+   [[YYR2[YYN] -- Number of symbols on the right hand side of rule YYN.]])
+])
+
+
+# b4_parser_tables_declare
+# b4_parser_tables_define
+# ------------------------
+# Define/declare the (deterministic) parser tables.
+m4_define([b4_parser_tables_declare],
+[b4_integral_parser_tables_map([b4_integral_parser_table_declare])])
+
+m4_define([b4_parser_tables_define],
+[b4_integral_parser_tables_map([b4_integral_parser_table_define])])
+
+
 
 ## ------------------ ##
 ## Decoding options.  ##
@@ -220,8 +299,8 @@ m4_define([b4_ints_in],
 m4_define([b4_flag_if],
 [m4_case(b4_$1_flag,
          [0], [$3],
-	 [1], [$2],
-	 [m4_fatal([invalid $1 value: ]$1)])])
+         [1], [$2],
+         [m4_fatal([invalid $1 value: ]b4_$1_flag)])])
 
 
 # b4_define_flag_if(FLAG)
@@ -247,20 +326,203 @@ m4_define([b4_$3_if],
 # -----------------------------
 # Expand IF-TRUE, if FLAG is true, IF-FALSE otherwise.
 b4_define_flag_if([defines])            # Whether headers are requested.
-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([token_table])        # Whether yytoken_table is demanded.
 b4_define_flag_if([yacc])               # Whether POSIX Yacc is emulated.
 
-# yytoken_table is needed to support verbose errors.
-b4_error_verbose_if([m4_define([b4_token_table_flag], [1])])
+
+## --------- ##
+## Symbols.  ##
+## --------- ##
+
+# In order to unify the handling of the various aspects of symbols
+# (tag, type_name, whether terminal, etc.), bison.exe defines one
+# macro per (token, field), where field can has_id, id, etc.: see
+# src/output.c:prepare_symbols_definitions().
+#
+# The various FIELDS are:
+#
+# - has_id: 0 or 1.
+#   Whether the symbol has an id.
+# - id: string
+#   If has_id, the id.  Guaranteed to be usable as a C identifier.
+# - tag: string.
+#   A representat of the symbol.  Can be 'foo', 'foo.id', '"foo"' etc.
+# - user_number: integer
+#   The assigned (external) number as used by yylex.
+# - is_token: 0 or 1
+#   Whether this is a terminal symbol.
+# - number: integer
+#   The internalized number (used after yytranslate).
+# - has_type: 0, 1
+#   Whether has a semantic value.
+# - type
+#   If it has a semantic value, its type tag, or, if variant are used,
+#   its type.
+# - has_printer: 0, 1
+# - printer: string
+# - printer_file: string
+# - printer_line: integer
+#   If the symbol has a printer, everything about it.
+# - has_destructor, destructor, destructor_file, destructor_line
+#   Likewise.
+#
+# The following macros provide access to these values.
+
+# b4_symbol_(NUM, FIELD)
+# ----------------------
+# Recover a FIELD about symbol #NUM.  Thanks to m4_indir, fails if
+# undefined.
+m4_define([b4_symbol_],
+[m4_indir([b4_symbol($1, $2)])])
+
+
+# b4_symbol(NUM, FIELD)
+# ---------------------
+# Recover a FIELD about symbol #NUM.  Thanks to m4_indir, fails if
+# undefined.  If FIELD = id, prepend the token prefix.
+m4_define([b4_symbol],
+[m4_case([$2],
+         [id],    [m4_do([b4_percent_define_get([api.token.prefix])],
+                         [b4_symbol_([$1], [id])])],
+         [b4_symbol_($@)])])
+
+
+# b4_symbol_if(NUM, FIELD, IF-TRUE, IF-FALSE)
+# -------------------------------------------
+# If FIELD about symbol #NUM is 1 expand IF-TRUE, if is 0, expand IF-FALSE.
+# Otherwise an error.
+m4_define([b4_symbol_if],
+[m4_case(b4_symbol([$1], [$2]),
+         [1], [$3],
+         [0], [$4],
+         [m4_fatal([$0: field $2 of $1 is not a Boolean:] b4_symbol([$1], [$2]))])])
+
+
+# b4_symbol_tag_comment(SYMBOL-NUM)
+# ---------------------------------
+# Issue a comment giving the tag of symbol NUM.
+m4_define([b4_symbol_tag_comment],
+[b4_comment([b4_symbol([$1], [tag])])
+])
+
+
+# b4_symbol_action_location(SYMBOL-NUM, KIND)
+# -------------------------------------------
+# Report the location of the KIND action as FILE:LINE.
+m4_define([b4_symbol_action_location],
+[b4_symbol([$1], [$2_file]):b4_syncline([b4_symbol([$1], [$2_line])])])
+
+
+# b4_symbol_action(SYMBOL-NUM, KIND)
+# ----------------------------------
+# Run the action KIND (destructor or printer) for SYMBOL-NUM.
+# Same as in C, but using references instead of pointers.
+m4_define([b4_symbol_action],
+[b4_symbol_if([$1], [has_$2],
+[b4_dollar_pushdef([(*yyvaluep)],
+                   b4_symbol_if([$1], [has_type],
+                                [m4_dquote(b4_symbol([$1], [type]))]),
+                   [(*yylocationp)])dnl
+    b4_symbol_case_([$1])[]dnl
+b4_syncline([b4_symbol([$1], [$2_line])], ["b4_symbol([$1], [$2_file])"])
+      b4_symbol([$1], [$2])
+b4_syncline([@oline@], [@ofile@])
+        break;
+
+b4_dollar_popdef[]dnl
+])])
+
+
+# b4_symbol_destructor(SYMBOL-NUM)
+# b4_symbol_printer(SYMBOL-NUM)
+# --------------------------------
+m4_define([b4_symbol_destructor], [b4_symbol_action([$1], [destructor])])
+m4_define([b4_symbol_printer],    [b4_symbol_action([$1], [printer])])
+
+
+# b4_symbol_case_(SYMBOL-NUM)
+# ---------------------------
+# Issue a "case NUM" for SYMBOL-NUM.
+m4_define([b4_symbol_case_],
+[case b4_symbol([$1], [number]): b4_symbol_tag_comment([$1])])
+])
 
 
-## ------------------------- ##
-## Assigning token numbers.  ##
-## ------------------------- ##
+# b4_symbol_foreach(MACRO)
+# ------------------------
+# Invoke MACRO(SYMBOL-NUM) for each SYMBOL-NUM.
+m4_define([b4_symbol_foreach],
+          [m4_map([$1], m4_defn([b4_symbol_numbers]))])
+
+# b4_symbol_map(MACRO)
+# --------------------
+# Return a list (possibly empty elements) of MACRO invoked for each
+# SYMBOL-NUM.
+m4_define([b4_symbol_map],
+[m4_map_args_sep([$1(], [)], [,], b4_symbol_numbers)])
+
+
+# b4_token_visible_if(NUM, IF-TRUE, IF-FALSE)
+# -------------------------------------------
+# Whether NUM denotes a token that has an exported definition (i.e.,
+# shows in enum yytokentype).
+m4_define([b4_token_visible_if],
+[b4_symbol_if([$1], [is_token],
+              [b4_symbol_if([$1], [has_id], [$2], [$3])],
+              [$3])])
+
+# b4_token_has_definition(NUM)
+# ----------------------------
+# 1 if NUM is visible, nothing otherwise.
+m4_define([b4_token_has_definition],
+[b4_token_visible_if([$1], [1])])
+
+# b4_any_token_visible_if([IF-TRUE], [IF-FALSE])
+# ----------------------------------------------
+# Whether there is a token that needs to be defined.
+m4_define([b4_any_token_visible_if],
+[m4_ifval(b4_symbol_foreach([b4_token_has_definition]),
+          [$1], [$2])])
+
+
+# b4_token_format(FORMAT, NUM)
+# ----------------------------
+m4_define([b4_token_format],
+[b4_token_visible_if([$2],
+[m4_quote(m4_format([$1],
+                     [b4_symbol([$2], [id])],
+                     [b4_symbol([$2], [user_number])]))])])
+
+
+## ------- ##
+## Types.  ##
+## ------- ##
+
+# b4_type_action_(NUMS)
+# ---------------------
+# Run actions for the symbol NUMS that all have the same type-name.
+# Skip NUMS that have no type-name.
+#
+# To specify the action to run, define b4_dollar_dollar(NUMBER,
+# TAG, TYPE).
+m4_define([b4_type_action_],
+[b4_symbol_if([$1], [has_type],
+[m4_map([      b4_symbol_case_], [$@])[]dnl
+        b4_dollar_dollar([b4_symbol([$1], [number])],
+                         [b4_symbol([$1], [tag])],
+                         [b4_symbol([$1], [type])]);
+        break;
+
+])])
+
+# b4_type_foreach(MACRO)
+# ----------------------
+# Invoke MACRO(SYMBOL-NUMS) for each set of SYMBOL-NUMS for each type set.
+m4_define([b4_type_foreach],
+          [m4_map([$1], m4_defn([b4_type_names]))])
+
 
 
 ## ----------- ##
@@ -278,12 +540,22 @@ m4_define([b4_basename],
 # b4_syncline(LINE, FILE)
 # -----------------------
 m4_define([b4_syncline],
-[b4_flag_if([synclines], [
-b4_sync_end([__line__], [b4_basename(m4_quote(__file__))])
-b4_sync_start([$1], [$2])])])
+[b4_flag_if([synclines],
+[b4_sync_start([$1], [$2]) b4_sync_end([__line__],
+                                       [b4_basename(m4_quote(__file__))])[]dnl
+])])
+
+# b4_sync_start(LINE, FILE)
+# -----------------------
+# Syncline for the new place.  Typically a directive for the compiler.
+m4_define([b4_sync_start], [b4_comment([$2:$1])])
+
+# b4_sync_end(LINE, FILE)
+# -----------------------
+# Syncline for the current place, which ends.  Typically a comment
+# left for the reader.
+m4_define([b4_sync_end],   [b4_comment([$2:$1])])
 
-m4_define([b4_sync_end], [b4_comment([Line $1 of $2])])
-m4_define([b4_sync_start], [b4_comment([Line $1 of $2])])
 
 # b4_user_code(USER-CODE)
 # -----------------------
@@ -368,7 +640,6 @@ m4_popdef([b4_end])dnl
 
 
 
-
 ## --------------------- ##
 ## b4_percent_define_*.  ##
 ## --------------------- ##
@@ -398,7 +669,6 @@ m4_ifdef([b4_percent_define(]$1[)],
          [m4_indir([b4_percent_define(]$1[)])],
          [$2])])
 
-
 # b4_percent_define_get_loc(VARIABLE)
 # -----------------------------------
 # Mimic muscle_percent_define_get_loc in ../src/muscle-tab.h exactly.  That is,
@@ -447,8 +717,14 @@ m4_define([b4_percent_define_get_syncline],
 #   b4_percent_define_ifdef([[foo]], [[it's defined]], [[it's undefined]])
 m4_define([b4_percent_define_ifdef],
 [m4_ifdef([b4_percent_define(]$1[)],
-	  [m4_define([b4_percent_define_bison_variables(]$1[)])$2],
-	  [$3])])
+          [b4_percent_define_use([$1])$2],
+          [$3])])
+
+
+## --------- ##
+## Options.  ##
+## --------- ##
+
 
 # b4_percent_define_flag_if(VARIABLE, IF-TRUE, [IF-FALSE])
 # --------------------------------------------------------
@@ -473,6 +749,7 @@ m4_define([b4_percent_define_flag_if],
                            [[b4_percent_define_flag_if($1)]])])],
   [b4_fatal([[b4_percent_define_flag_if: undefined %%define variable '%s']], [$1])])])
 
+
 # b4_percent_define_default(VARIABLE, DEFAULT)
 # --------------------------------------------
 # Mimic muscle_percent_define_default in ../src/muscle-tab.h exactly.  That is,
@@ -491,6 +768,21 @@ m4_define([b4_percent_define_default],
                         [[<skeleton default value>:-1.-1]]]])dnl
             m4_define([b4_percent_define_syncline(]$1[)], [[]])])])
 
+
+# b4_percent_define_if_define(NAME, [VARIABLE = NAME])
+# ----------------------------------------------------
+# Define b4_NAME_if that executes its $1 or $2 depending whether
+# VARIABLE was %defined.  The characters `.' and `-' in VARIABLE are mapped
+# to `_'.
+m4_define([b4_percent_define_if_define_],
+[m4_define(m4_bpatsubst([b4_$1_if], [[-.]], [_]),
+           [b4_percent_define_flag_if(m4_default([$2], [$1]),
+                                      [$3], [$4])])])
+m4_define([b4_percent_define_if_define],
+[b4_percent_define_default([m4_default([$2], [$1])], [[false]])
+b4_percent_define_if_define_([$1], [$2], $[1], $[2])])
+
+
 # b4_percent_define_check_values(VALUES)
 # --------------------------------------
 # Mimic muscle_percent_define_check_values in ../src/muscle-tab.h exactly
@@ -524,7 +816,7 @@ m4_define([_b4_percent_define_check_values],
                          [$1],
                          m4_dquote(m4_indir([b4_percent_define(]$1[)])))
           m4_foreach([b4_value], m4_dquote(m4_shift($@)),
-                     [b4_complain_at(b4_percent_define_get_loc([$1]),
+                     [b4_error([[note]], b4_percent_define_get_loc([$1]), []
                                      [[accepted value: '%s']],
                                      m4_dquote(b4_value))])])dnl
    m4_popdef([b4_good_value])],
@@ -562,7 +854,60 @@ m4_popdef([b4_macro_name])])
 m4_define([b4_percent_code_ifdef],
 [m4_ifdef([b4_percent_code(]$1[)],
           [m4_ifval([$1], [m4_define([b4_percent_code_bison_qualifiers(]$1[)])])$2],
-	  [$3])])
+          [$3])])
+
+
+## ------------------ ##
+## Common variables.  ##
+## ------------------ ##
+
+# Default values for %define.
+# ---------------------------
+# If the api.token.prefix, it is empty.
+m4_percent_define_default([[api.token.prefix]], [[]])
+
+# b4_parse_assert_if([IF-ASSERTIONS-ARE-USED], [IF-NOT])
+# b4_parse_trace_if([IF-DEBUG-TRACES-ARE-ENABLED], [IF-NOT])
+# b4_token_ctor_if([IF-YYLEX-RETURNS-A-TOKEN], [IF-NOT])
+# ----------------------------------------------
+b4_percent_define_if_define([token_ctor], [api.token.constructor])
+b4_percent_define_if_define([locations])     # Whether locations are tracked.
+b4_percent_define_if_define([parse.assert])
+b4_percent_define_if_define([parse.trace])
+
+
+# b4_bison_locations_if([IF-TRUE])
+# --------------------------------
+# Expand IF-TRUE if using locations, and using the default location
+# type.
+m4_define([b4_bison_locations_if],
+[b4_locations_if([b4_percent_define_ifdef([[api.location.type]], [], [$1])])])
+
+
+# b4_error_verbose_if([IF-ERRORS-ARE-VERBOSE], [IF-NOT])
+# ------------------------------------------------------
+# Map %define parse.error "(simple|verbose)" to b4_error_verbose_if and
+# b4_error_verbose_flag.
+b4_percent_define_default([[parse.error]], [[simple]])
+b4_percent_define_check_values([[[[parse.error]],
+                                 [[simple]], [[verbose]]]])
+m4_define([b4_error_verbose_flag],
+          [m4_case(b4_percent_define_get([[parse.error]]),
+                   [simple],  [[0]],
+                   [verbose], [[1]])])
+b4_define_flag_if([error_verbose])
+
+# yytoken_table is needed to support verbose errors.
+b4_error_verbose_if([m4_define([b4_token_table_flag], [1])])
+
+
+# b4_variant_if([IF-VARIANT-ARE-USED], [IF-NOT])
+# ----------------------------------------------
+b4_percent_define_if_define([variant])
+m4_case(b4_percent_define_get([[api.value.type]]),
+        [variant], [m4_define([b4_variant_flag], [[1]])],
+                   [m4_define([b4_variant_flag], [[0]])])
+b4_define_flag_if([variant])
 
 
 ## ----------------------------------------------------------- ##
@@ -580,3 +925,26 @@ m4_wrap_lifo([
 b4_check_user_names_wrap([[define]], [[variable]])
 b4_check_user_names_wrap([[code]], [[qualifier]])
 ])
+
+
+## ---------------- ##
+## Default values.  ##
+## ---------------- ##
+
+# m4_define_default([b4_lex_param], [])   dnl breaks other skeletons
+m4_define_default([b4_pre_prologue], [])
+m4_define_default([b4_post_prologue], [])
+m4_define_default([b4_epilogue], [])
+m4_define_default([b4_parse_param], [])
+
+# The initial column and line.
+m4_define_default([b4_location_initial_column], [1])
+m4_define_default([b4_location_initial_line],   [1])
+
+# Sanity checks.
+b4_percent_define_ifdef([api.prefix],
+[m4_ifdef([b4_prefix],
+[b4_complain_at(b4_percent_define_get_loc([api.prefix]),
+                [['%s' and '%s' cannot be used together]],
+                [%name-prefix],
+                [%define api.prefix])])])