This is a backport cherry-pick of commits
165156beebcce974e8ea
from the v3.0 branch as we need symbol hashes directly inside their
scopes for more general usage than before.
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.
For whatever reason, parser allocated a symbol for every parsed keyword
in each scope. That wasted time and memory. The effect is worsened with
recent changes allowing local scopes, so keywords often promote soft
scopes (with no symbols) to real scopes.
Do not allocate a symbol for a keyword. Take care of keywords that could
be promoted to symbols (kw_sym) and do it explicitly.
Some of these new BGP role keywords use generic names that collides with
user-defined symbols. Allow them to be redefined. Also remove duplicit
keyword definition for 'prefer'.
Some tokens are both keywords and symbols. For now, we allow only
specific keywords to be redefined; in future, more of the keywords may
be added to this category.
The redefinable keywords must be specified in any .Y file as follows:
toksym: THE_KEYWORD ;
See proto/bgp/config.Y for an example.
Also dropped a lot of unused terminals.
Several new configure command variants:
configure undo - undo last reconfiguration
configure timeout - configure with scheduled undo if not confirmed in timeout
configure confirm - confirm last configuration
configure check - just parse and validate config file
we want to allow filter and similar complex constructs to be used in commands
and we should avoid code duplication), only with CLI_MARKER token prepended
before the whole input.
Defined macro CF_CLI(cmd, args, help) for defining CLI commands in .Y files.
The first argument specifies the command itself, the remaining two arguments
are copied to the help file (er, will be copied after the help file starts
to exist). This macro automatically creates a skeleton rule for the command,
you only need to append arguments as in:
CF_CLI(STEAL MONEY, <$>, [[Steal <$> US dollars or equivalent in any other currency]]): NUM {
cli_msg(0, "%d$ stolen", $3);
} ;
Also don't forget to reset lexer state between inputs.
