ast.rb

require 'parslet'
require 'pry'

module Rip::Compiler
  class AST < Parslet::Transform
    attr_reader :origin

    def initialize(origin)
      @origin = origin
    end

    rule(:comment => simple(:comment)) do |tokens|
      # this block never gets called
      comment = tokens[:comment]
      location = location_for(comment)
      Rip::Nodes::Comment.new(location, comment)
    end

    def apply(tree, context = nil)
      binding.pry
      super
    end

    protected

    def location_for(slice)
      Rip::Utilities::Location.new(origin, *slice.line_and_column)
    end
  end
end

session

% cat >> spec/fixtures/comment.rip
# comment me, bro
^d
% ./bin/rip debug -t syntax spec/fixtures/comment.rip

From: /Users/thomas/Code/rip-rip/lib/rip/compiler/ast.rb @ line 20 Rip::Compiler::AST#apply:

    19: def apply(tree, context = nil)
 => 20:   binding.pry
    21:   super
    22: end

[1] pry(#<Rip::Compiler::AST>)> tree
=> [{:comment=>" comment me, bro"@1}]
[2] pry(#<Rip::Compiler::AST>)> exit

From: /Users/thomas/Code/rip-rip/lib/rip/compiler/ast.rb @ line 20 Rip::Compiler::AST#apply:

    19: def apply(tree, context = nil)
 => 20:   binding.pry
    21:   super
    22: end

[1] pry(#<Rip::Compiler::AST>)> tree
=> {:comment=>" comment me, bro"@1}
[2] pry(#<Rip::Compiler::AST>)> exit

From: /Users/thomas/Code/rip-rip/lib/rip/compiler/ast.rb @ line 20 Rip::Compiler::AST#apply:

    19: def apply(tree, context = nil)
 => 20:   binding.pry
    21:   super
    22: end

[1] pry(#<Rip::Compiler::AST>)> tree
=> " comment me, bro"@1
[2] pry(#<Rip::Compiler::AST>)> exit
/Users/thomas/Code/rip-parslet/lib/parslet/transform.rb:206:in `+': no implicit conversion of nil into Array (TypeError)
  from /Users/thomas/Code/rip-parslet/lib/parslet/transform.rb:206:in `rules'
	from /Users/thomas/Code/rip-parslet/lib/parslet/transform.rb:212:in `transform_elt'
	from /Users/thomas/Code/rip-parslet/lib/parslet/transform.rb:165:in `apply'
	from /Users/thomas/Code/rip-rip/lib/rip/compiler/ast.rb:21:in `apply'
	from /Users/thomas/Code/rip-parslet/lib/parslet/transform.rb:227:in `block in recurse_hash'
	from /Users/thomas/Code/rip-parslet/lib/parslet/transform.rb:226:in `each'
	from /Users/thomas/Code/rip-parslet/lib/parslet/transform.rb:226:in `inject'
	from /Users/thomas/Code/rip-parslet/lib/parslet/transform.rb:226:in `recurse_hash'
	from /Users/thomas/Code/rip-parslet/lib/parslet/transform.rb:168:in `apply'
	from /Users/thomas/Code/rip-rip/lib/rip/compiler/ast.rb:21:in `apply'
	from /Users/thomas/Code/rip-parslet/lib/parslet/transform.rb:234:in `block in recurse_array'
	from /Users/thomas/Code/rip-parslet/lib/parslet/transform.rb:234:in `map'
	from /Users/thomas/Code/rip-parslet/lib/parslet/transform.rb:234:in `recurse_array'
	from /Users/thomas/Code/rip-parslet/lib/parslet/transform.rb:170:in `apply'
	from /Users/thomas/Code/rip-rip/lib/rip/compiler/ast.rb:21:in `apply'
	from /Users/thomas/Code/rip-rip/lib/rip/compiler/parser.rb:16:in `syntax_tree'
	from /Users/thomas/Code/rip-rip/lib/rip/cli.rb:86:in `syntax_tree'
	from /Users/thomas/Code/rip-rip/lib/rip/cli.rb:56:in `debug'
	from /usr/local/opt/rbenv/versions/2.0.0-p0/lib/ruby/gems/2.0.0/gems/thor-0.17.0/lib/thor/task.rb:27:in `run'
	from /usr/local/opt/rbenv/versions/2.0.0-p0/lib/ruby/gems/2.0.0/gems/thor-0.17.0/lib/thor/invocation.rb:120:in `invoke_task'
	from /usr/local/opt/rbenv/versions/2.0.0-p0/lib/ruby/gems/2.0.0/gems/thor-0.17.0/lib/thor.rb:344:in `dispatch'
	from /usr/local/opt/rbenv/versions/2.0.0-p0/lib/ruby/gems/2.0.0/gems/thor-0.17.0/lib/thor/base.rb:434:in `start'
	from ./bin/rip:5:in `<main>'

Try this.

require 'parslet'
require 'pry'

module Rip::Compiler
  class AST < Parslet::Transform
    attr_reader :origin

    def initialize(origin,&block)
      @@origin = origin
      super(&block)
    end

    rule(:comment => simple(:comment)) do |tokens|
      # this block never gets called
      comment = tokens[:comment]
      location = location_for(comment)
      Rip::Nodes::Comment.new(location, comment)
    end

    def apply(tree, context = nil)
#      binding.pry
      super
    end

    protected

    def self.location_for(slice)
      Rip::Utilities::Location.new(@@origin, "??", *(slice.line_and_column))
    end
  end
end