add_cmd non-terminal symbol in Bison parser needs to go on a diet

[S Egbert <s.egbert@xxxxxxxxxxxxx>]

After perusing the entire Netfilter syntax tree in preparation for 
autocompletion, I've made a preliminary analysis that 'add_cmd' 
non-terminal symbol is in need of a reduction into a smaller parser element.

For those needing a diagram, I've posted the XHTML file of Netfilter 
railroad diagram in:

 
https://github.com/egberts/vim-nftables/blob/master/doc/nftables-railroad-chart.xhtml

The railroad chart of Netfilter 'nft' CLI needs to be viewed using a web 
browser as GitHub website doesn't render a standalone XHTML file, but 
you can view it locally and nicely using a 'file:///' in the URL box.


The current 'add_cmd' symbol in Netfilter Bison (src/parser_bison.c) 
comprises of the following required first (1st) token symbols:

  table
  chain
  rule
    ip
    ip6
    inet
    arp
    bridge
    netdev
    <table_id>
  set
  map
  flowtable
  element
  counter
  quota
  ct
  limit
  secmark
  synproxy

The current 'add_cmd' parser is supporting some keywords that the 'nft' 
CLI tool does not support.  This also interferes with any planned 
autocompletion effort.


An updated 'add_cmd' non-terminal symbol could be updated to match the 
current 'nft' CLI tool:

new_add_cmd

  table
  chain
  rule
    ip
    ip6
    inet
    arp
    bridge
    netdev
    <table_id>

What remains unchanged is the 'table_block' element (that is inside the

    table [ <family_spec_explicit> ] <table_id> <chain_id>
        {
            table_block
        };

which would already covered the basic usage with the following starting 
token symbols:

    create
      chain
      rule
        ip
        ip6
        inet
        arp
        bridge
        netdev
        <table_id>
      set
      map
      flowtable
      element
      counter
      quota
      ct
      limit
      secmark
      synproxy

The 'create_cmd' non-terminal symbol would already cover the remaining 
for creation needs of Netfilter:

    create
      table
      chain
      set
      map
      flowtable
      element
      counter
      quota
      ct
      limit
      secmark
      synproxy


This would accelerate ANY autocompletion greatly for our ideal 
multi-context multi-token manner, as well as a JSON outputter.

If the above proves to be ideal, then the true first/starting token list 
would be covered by the 'line' and 'base_cmd' (and otherwise indicated):

  chain
  rule
    ip
    ip6
    inet
    arp
    bridge
    netdev
    <table_identifier>
  replace
  create
  insert
  delete
  get
  list
  reset
  flush
  rename
  import
  export
  monitor
  describe
  destroy
  include (common_block)
  define (common_block)
  redefine (common_block)
  undefine (common_block)
  error (common_block)
  ';' (stmt_separator)
  '\n' (stmt_separator)

Always looking for a better way ...

S Egbert