0
0
mirror of https://gitlab.nic.cz/labs/bird.git synced 2024-11-17 16:48:43 +00:00
bird/conf/gen_parser.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

78 lines
2.2 KiB
Plaintext

m4_divert(-1)m4_dnl
#
# BIRD -- Generator of Configuration Grammar
#
# (c) 1998--1999 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
#
# Can be freely distributed and used under the terms of the GNU GPL.
#
# Diversions used:
# 1 includes
# 2 types etc.
# 3 rules
# 4 C code
# Common aliases
m4_define(DNL, `m4_dnl')
# Define macros for defining sections
m4_define(CF_ZONE, `m4_divert($1)/* $2 from m4___file__ */')
m4_define(CF_HDR, `CF_ZONE(1, Headers)')
m4_define(CF_DEFINES, `CF_ZONE(1, Defines)')
m4_define(CF_DECLS, `CF_ZONE(2, Declarations)')
m4_define(CF_GRAMMAR, `CF_ZONE(3, Grammar)')
m4_define(CF_CODE, `CF_ZONE(4, C Code)')
m4_define(CF_END, `m4_divert(-1)')
# Simple iterator
m4_define(CF_itera, `m4_ifelse($#, 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)')
m4_define(CF_append, `m4_define([[$1]], m4_ifdef([[$1]], m4_defn([[$1]])[[$3]])[[$2]])')
# Keywords act as %token<kw>
m4_define(CF_keywd, `m4_ifdef([[CF_tok_$1]],,[[m4_define([[CF_tok_$1]],1)CF_append([[CF_kw_rule]],$1,[[ | ]])m4_define([[CF_toks]],CF_toks $1)]])')
m4_define(CF_KEYWORDS, `m4_define([[CF_toks]],[[]])CF_iterate([[CF_keywd]], [[$@]])m4_ifelse(CF_toks,,,%token<kw>[[]]CF_toks
)DNL')
m4_define(CF_keywd2, `m4_ifdef([[CF_tok_$1]],,[[m4_define([[CF_tok_$1]],1)m4_define([[CF_toks]],CF_toks $1)]])')
m4_define(CF_KEYWORDS_EXCLUSIVE, `m4_define([[CF_toks]],[[]])CF_iterate([[CF_keywd2]], [[$@]])m4_ifelse(CF_toks,,,%token<kw>[[]]CF_toks
)DNL')
# CLI commands
m4_define(CF_CLI, `m4_define([[CF_cmd]], cmd_[[]]m4_translit($1, [[ ]], _))DNL
m4_divert(2)CF_KEYWORDS(m4_translit($1, [[ ]], [[,]]))
m4_divert(3)cli_cmd: CF_cmd
CF_cmd: $1 $2 END')
m4_define(CF_CLI_CMD, `')
m4_define(CF_CLI_HELP, `')
# ENUM declarations are ignored
m4_define(CF_ENUM, `')
m4_define(CF_ENUM_PX, `')
# After all configuration templates end, we finally generate the grammar file.
m4_m4wrap(`
m4_divert(0)DNL
%{
m4_undivert(1)DNL
%}
m4_undivert(2)DNL
%type <kw> KEYWORD
%%
KEYWORD: CF_kw_rule;
m4_undivert(3)DNL
%%
m4_undivert(4)DNL
')
# As we are processing C source, we must access all M4 primitives via
# m4_* and also set different quoting convention: `[[' and ']]'
m4_changequote([[,]])