a19.tt

data rule <{id: <id>, subrules: <subrules> VOID}|{id: <id>, match: <match> VOID}>,
     rules <[<rule>* VOID]>
composer parseRule
  {id: <INT> (<=': '>), <match|list>}
  rule match: match: (<='"'>) <'.'> (<='"'>)
  rule list: subrules: [<option>+]
  rule option: [<ref>+] (<=' | '>?)
  rule ref: <INT> (<WS>?)
end parseRule

source getInput
  @: [];
  {$IN::lines -> #, messages: $@} !

  when <=''> do
    (rules:[$@... -> parseRule]) !
    @: [];
  otherwise
    ..|@: $;
end getInput

def input: $getInput;

templates collectRules
  @: [];
  $... -> #
  $@!
  when <{id: <$@::length..>}> do
    $@::length..$.id::raw -> ..|@: {};
    $ -> #
  otherwise
    @($.id::raw+1): $;
end collectRules

templates resolveRules
  @: $;
  [1..$::length -> #] !
  
  when <?($@($) <´´ '.*'>)> do
    $@($)!
  when <?($@($) <´rule´ {match: <>}>)> do
    @($): '$@($).match;'; $@($)!
  when <?($@($) <{subrules: <[](1)>}>)> do
    @($): '$@($).subrules(1)... -> $+1 -> #;'; '$@($);'!
  when <?($@($) <{subrules: <[](2..)>}>)> do
    def i: $;
    [$@($i).subrules... -> '$... -> $+1 ->#;'] ->
      @($i): '($(1);$(2..last)...->'|$;';)';
    $@($i)!
  otherwise
    '$; ' -> !OUT::write
    '$@($);$#10;' -> !OUT::write
    '' !
end resolveRules

def rules: $input.rules -> collectRules -> resolveRules;

composer completelyMatches&{rule:}
  @: 1;
  (<match|not>+) $@
  rule match: (<'$rule;'>)
  rule not: (<~match> -> @: 0;)
end completelyMatches

// part1
$input.messages -> \(
  @: 0;
  $... -> completelyMatches&{rule: $rules(1)} -> @: $@ + $;
  $@!
\) -> '$;
' -> !OUT::write

// part2
// assume rules 42 and 31 don't depend on 8 and 11
def fortytwo: $rules(43);
def thirtyone: $rules(32);

// returns nothing if it matches, else an error object
composer failsNewRuleZero
  (<eight> <eleven>)
  rule eight: (<'$fortytwo;'> <eight>?)
  rule eleven: (<'$fortytwo;'> <eleven>? <'$thirtyone;'>)
end failsNewRuleZero

$input.messages -> \(
  @: $::length;
  $... -> failsNewRuleZero -> @: $@ - 1;
  $@!
\) -> '$;
' -> !OUT::write