rpl.rb/lib/parser.rb

# frozen_string_literal: true

module Rpl
  module Lang
    class Parser
      def initialize; end

      def numeric?( elt )
        !Float(elt).nil?
      rescue ArgumentError
        begin
          !Integer(elt).nil?
        rescue ArgumentError
          false
        end
      end

      def parse_input( input )
        splitted_input = input.split(' ')

        # 2-passes:
        # 1. regroup strings and programs
        opened_programs = 0
        closed_programs = 0
        string_delimiters = 0
        regrouping = false

        regrouped_input = []
        splitted_input.each do |elt|
          # TODO: handle buried-in-elt « and » (surround by ' ' and re-split)
          if elt[0] == '«'
            opened_programs += 1
            elt.gsub!( '«', '« ') if elt.length > 1 && elt[1] != ' '
          end
          string_delimiters += 1 if elt[0] == '"'

          elt = "#{regrouped_input.pop} #{elt}".strip if regrouping

          regrouped_input << elt

          if elt[-1] == '»'
            closed_programs += 1
            elt.gsub!( '»', ' »') if elt.length > 1 && elt[-2] != ' '
          end
          string_delimiters += 1 if elt.length > 1 && elt[-1] == '"'

          regrouping = string_delimiters.odd? || (opened_programs > closed_programs )
        end

        # 2. parse
        parsed_tree = []
        regrouped_input.each do |elt|
          parsed_entry = { value: elt }

          opened_programs += 1 if elt[0] == '«'
          string_delimiters += 1 if elt[0] == '"'

          parsed_entry[:type] = case elt[0]
                                when '«'
                                  :program
                                when '"'
                                  :string
                                when "'"
                                  :name # TODO: check for forbidden space
                                else
                                  if numeric?( elt )
                                    :numeric
                                  else
                                    :word
                                  end
                                end

          if parsed_entry[:type] == :numeric
            parsed_entry[:base] = 10 # TODO: parse others possible bases 0x...

            begin
              parsed_entry[:value] = Float( parsed_entry[:value] )
            rescue ArgumentError
              parsed_entry[:value] = Integer( parsed_entry[:value] )
            end
          end

          parsed_tree << parsed_entry
        end

        parsed_tree
      end
    end
  end
end