# encoding: utf-8
# frozen_string_literal: true

module Carbon
  module Compiler
    class Parser
      # Parses common items, such as module names and types.
      module Common
      protected

        Parser.first(:name, [:IDENTIFIER, :module, :struct, :enum, :trait,
          :def, :self, :_])
        def parse_name
          error(first(:name)) unless first(:name).include?(peek.type)
          Node::Name.new([shift])
        end

        # TODO: pointer
        Parser.first(:type, [:MNAME, :"("])
        def parse_type
          type =
            case peek.type
            when :MNAME then parse_module_name
            when :"("   then parse_unit_type
            else error first(:type)
            end
        end

        def parse_unit_type
          expect :"("
          children = []
          until peek? :")"
            children << parse_type
            break unless peek? :","
            expect :","
          end
          expect :")"

          Node::Type::Unit.new(children)
        end

        def parse_module_name
          base = parse_module_name_part
          children = [base]
          while peek? :"::"
            expect :"::"
            children << parse_module_name_part
          end

          location = children.map(&:location).inject(:|)
          Concrete::Type.new(Concrete::Type::Name.new(children, nil),
            location: location)
        end

        def parse_module_name_part
          root = expect :MNAME
          generics = peek?(:<) ? parse_module_generics : []
          location = [root].concat(generics).map(&:location).inject(:|)
          Concrete::Type::Part.new(root.value, generics, location: location)
        end

        def parse_module_generics
          children = []
          expect :<
          until peek? :>
            name = parse_module_name
            children << Concrete::Type::Generic.new(name, [],
              location: name.location)
            break unless peek? :","
            expect :","
          end
          expect :>

          children
        end
      end
    end
  end
end