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bird/conf/gen_keywords.m4
Ondrej Zajicek f5140d1027 Conf: Allow keywords to be redefined by user symbols
Most syntactic constructs in BIRD configuration (e.g. protocol options)
are defined as keywords, which are distinct from symbols (user-defined
names for protocols, variables, ...). That may cause backwards
compatibility issue when a new feature is added, as it may collide with
existing user names.

We can allow keywords to be shadowed by symbols in almost all cases to
avoid this issue.

This replaces the previous mechanism, where shadowable symbols have to be
explictly added to kw_syms.
2023-08-25 23:50:44 +02:00

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m4_divert(-1)m4_dnl
#
# BIRD -- Generator of Configuration Keyword List
#
# (c) 1998--2000 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
#
# Can be freely distributed and used under the terms of the GNU GPL.
#
# Common aliases
m4_define(DNL, `m4_dnl')
# Diversions used:
# 1 keywords
# Simple iterator
m4_define(CF_itera, `m4_ifelse($#, 1, [[CF_iter($1)]], [[CF_iter($1)[[]]CF_itera(m4_shift($@))]])')
m4_define(CF_iterate, `m4_define([[CF_iter]], m4_defn([[$1]]))CF_itera($2)')
# We include all the headers
m4_define(CF_HDR, `m4_divert(0)')
m4_define(CF_DECLS, `m4_divert(-1)')
m4_define(CF_DEFINES, `m4_divert(-1)')
# Keywords are translated to C initializers
m4_define(CF_handle_kw, `m4_divert(1){ "m4_translit($1,[[A-Z]],[[a-z]])", $1, NULL },
m4_divert(-1)')
m4_define(CF_keywd, `m4_ifdef([[CF_tok_$1]],,[[m4_define([[CF_tok_$1]],1)CF_handle_kw($1)]])')
m4_define(CF_KEYWORDS, `m4_define([[CF_toks]],[[]])CF_iterate([[CF_keywd]], [[$@]])m4_ifelse(CF_toks,,,%token[[]]CF_toks
)DNL')
m4_define(CF_KEYWORDS_EXCLUSIVE, `CF_KEYWORDS($@)')
# CLI commands generate keywords as well
m4_define(CF_CLI, `CF_KEYWORDS(m4_translit($1, [[ ]], [[,]]))
')
# Enums are translated to C initializers: use CF_ENUM(typename, prefix, values)
# For different prefix: CF_ENUM_PX(typename, external prefix, C prefix, values)
m4_define(CF_enum, `m4_divert(1){ "CF_enum_prefix_ext[[]]$1", -((CF_enum_type<<16) | CF_enum_prefix_int[[]]$1), NULL },
m4_divert(-1)')
m4_define(CF_ENUM, `m4_define([[CF_enum_type]],$1)m4_define([[CF_enum_prefix_ext]],$2)m4_define([[CF_enum_prefix_int]],$2)CF_iterate([[CF_enum]], [[m4_shift(m4_shift($@))]])DNL')
m4_define(CF_ENUM_PX, `m4_define([[CF_enum_type]],$1)m4_define([[CF_enum_prefix_ext]],$2)m4_define([[CF_enum_prefix_int]],$3)CF_iterate([[CF_enum]], [[m4_shift(m4_shift(m4_shift($@)))]])DNL')
# After all configuration templates end, we generate the
m4_m4wrap(`
m4_divert(0)
static struct keyword keyword_list[] = {
m4_undivert(1){ NULL, -1, NULL } };
')
# As we are processing C source, we must access all M4 primitives via
# m4_* and also set different quoting convention: `[[' and ']]'
m4_changequote([[,]])