+## --------- ##
+## Symbols. ##
+## --------- ##
+
+# 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 prefix.
+m4_define([b4_symbol],
+[m4_case([$2],
+ [id], [m4_do([b4_percent_define_get([api.tokens.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_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],
+[m4_pushdef([b4_dollar_dollar],
+ [b4_symbol_value([(*yyvaluep)],
+ b4_symbol_if([$1], [has_type],
+ [b4_symbol([$1], [type])]))])dnl
+m4_pushdef([b4_at_dollar], [(*yylocationp)])dnl
+ b4_symbol_case_([$1])
+b4_syncline([b4_symbol([$1], [$2_line])], ["b4_symbol([$1], [$2_file])"])
+ b4_symbol([$1], [$2])
+b4_syncline([@oline@], [@ofile@])
+ break;
+
+m4_popdef([b4_at_dollar])dnl
+m4_popdef([b4_dollar_dollar])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([$1], [tag])
+])
+
+
+# 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]))])
+
+
+## ------- ##
+## 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.
+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]))])
+
+
+