# Macro invocation - no arguments

a!();
b![];
c!{}
d::e!();
f::g::h!{}

==>

SourceFile(
  MacroInvocation(Identifier, ParenthesizedTokens),
  MacroInvocation(Identifier, BracketedTokens),
  MacroInvocation(Identifier, BracedTokens),
  MacroInvocation(ScopedIdentifier(ScopeIdentifier, Identifier), ParenthesizedTokens),
  MacroInvocation(ScopedIdentifier(ScopeIdentifier, ScopeIdentifier, Identifier), BracedTokens))


# Macro invocation - arbitrary tokens

a!(* a *);
a!(& a &);
a!(- a -);
a!(b + c + +);
a!('a'..='z');
a!('\u{0}'..='\u{2}');
a!('lifetime);

==>

SourceFile(
  MacroInvocation(
    Identifier,
    ParenthesizedTokens(ArithOp, Identifier, ArithOp)),
  MacroInvocation(
    Identifier,
    ParenthesizedTokens(BitOp, Identifier, BitOp)),
  MacroInvocation(
    Identifier,
    ParenthesizedTokens(ArithOp, Identifier, ArithOp)),
  MacroInvocation(
    Identifier,
    ParenthesizedTokens(Identifier, ArithOp, Identifier, ArithOp, ArithOp)),
  MacroInvocation(
    Identifier,
    ParenthesizedTokens(Char, Char)),
  MacroInvocation(
    Identifier,
    ParenthesizedTokens(Char, Char)),
  MacroInvocation(
    Identifier,
    ParenthesizedTokens(Lifetime)))


# Macro definition

macro_rules! say_hello {
    () => (
        println!("Hello!");
    )
}

macro_rules! four {
    () => {1 + 3};
}

macro_rules! foo {
    (x => $e:expr) => (println!("mode X: {}", $e));
    (y => $e:expr) => (println!("mode Y: {}", $e))
}

macro_rules! o_O {
    (
      $($x:expr; [ $( $y:expr ),* ]);*
    ) => {
      $($($x + $e),*),*
    }
}

macro_rules! zero_or_one {
    ($($e:expr),?) => {
        $($e),?
    };
}

==>

SourceFile(
  MacroDefinition(macro_rules,
    Identifier,
    MacroRule(
      ParenthesizedTokens,
      ParenthesizedTokens(
        Identifier,
        ParenthesizedTokens(String)))),
  MacroDefinition(macro_rules,
    Identifier,
    MacroRule(
      ParenthesizedTokens,
      BracedTokens(Integer, ArithOp, Integer))),
  MacroDefinition(macro_rules,
    Identifier,
    MacroRule(
      ParenthesizedTokens(
        Identifier,
        TokenBinding(
          Metavariable,
          Identifier)),
      ParenthesizedTokens(
        Identifier,
        ParenthesizedTokens(
          String,
          Metavariable))),
    MacroRule(
      ParenthesizedTokens(
        Identifier,
        TokenBinding(
          Metavariable,
          Identifier)),
      ParenthesizedTokens(
        Identifier,
        ParenthesizedTokens(
          String,
          Metavariable)))),
  MacroDefinition(macro_rules,
    Identifier,
    MacroRule(
      ParenthesizedTokens(
        TokenRepetition(
          TokenBinding(
            Metavariable,
            Identifier),
          BracketedTokens(
            TokenRepetition(
              TokenBinding(
                Metavariable,
                Identifier))))),
      BracedTokens(
        TokenRepetition(
          TokenRepetition(Metavariable, ArithOp, Metavariable))))),
  MacroDefinition(macro_rules,
    Identifier,
    MacroRule(
      ParenthesizedTokens(
        TokenRepetition(
          TokenBinding(Metavariable, Identifier))),
      BracedTokens(
        TokenRepetition(Metavariable)))))