unit class CleanAST; our $*Parens is export(:Parens); role Parens is Grammar is export(:Parens) { token lparen { '(' {$*Parens++} } token rparen { ')' {$*Parens--} } } # Example of a helper method: sub ast-from-first-child { CALLERS::('$/').caps[0].value.ast } method TOP ($/) { # These two lines could be replaced by a call to the above helper method: with $ { make $.ast } with $ { make $.ast } } method EXPR ($/) { # Example of using the above helper method: make ast-from-first-child; # Instead of these two lines: # with $ { make $.ast } # with $ { make $.ast } } method INFIX ($/) { # These two lines could be replaced by a call to a helper routine for ast # nodes which are just strings corresponding to their grammar rule name: with $ { make 'ADD' } with $ { make 'MUL' } } method VAL ($/) { # These two lines could be replaced by a call to a helper routine for ast # nodes which are strings constructed based on their grammar rule name: with $ { make q:s [IDENT{ str:"$" }] } with $ { make q:s [NUM{ num:"$" }] } } method INFIX-EXPR ($/) { # This code could be replaced by a call to a helper routine that handles the # desired ast formatting for an infix expression. Obviously there could be # helper routines for other typical grammatical slots (prefix, postfix, etc.) my $infix-and-curly = q:s:to.chop; $.ast() { left: $[0].ast(), right: $[1].ast() } END # If indent level above zero, expand indent as appropriate if try $*Parens { $infix-and-curly.=subst: :g, / ^^ ' ' /, ' ' x $*Parens+1; $infix-and-curly.=subst: / ^^ /, ' ' x $*Parens; } make $infix-and-curly; }