rpl.rb/lib/core/stack.rb

# frozen_string_literal: true

module Lang
  module Core
    module_function

    # swap 2 first stack entries
    def swap
      args = stack_extract( %i[any any] )

      @stack << args[0] << args[1]
    end

    # drop n first stack entries
    def dropn
      args = stack_extract( [%i[numeric]] )

      _args = stack_extract( %i[any] * args[0][:value] )
    end

    # drop all stack entries
    def del
      @stack = []
    end

    # rotate 3 first stack entries
    def rot
      args = stack_extract( %i[any any any] )

      @stack << args[1] << args[0] << args[2]
    end

    # duplicate n first stack entries
    def dupn
      args = stack_extract( [%i[numeric]] )
      n = args[0][:value].to_i
      args = stack_extract( %i[any] * args[0][:value] )

      args.reverse!

      2.times do
        n.times.each do |i|
          @stack << Marshal.load(Marshal.dump( args[i] ))
        end
      end
    end

    # push a copy of the given stack level onto the stack
    def pick
      args = stack_extract( [%i[numeric]] )
      n = args[0][:value].to_i
      args = stack_extract( %i[any] * args[0][:value] )

      args.reverse!

      n.times.each do |i|
        @stack << args[ i ]
      end

      @stack << args[0]
    end

    # give stack depth
    def depth
      @stack << { type: :numeric, base: 10, value: stack.size }
    end

    # move a stack entry to the top of the stack
    def roll
      args = stack_extract( [%i[numeric]] )
      n = args[0][:value]
      args = stack_extract( %i[any] * args[0][:value] )

      args.reverse!

      (1..(n - 1)).each do |i|
        @stack << args[ i ]
      end

      @stack << args[0]
    end

    # move the element on top of the stack to a higher stack position
    def rolld
      args = stack_extract( [%i[numeric]] )
      n = args[0][:value]
      args = stack_extract( %i[any] * args[0][:value] )

      args.reverse!

      @stack << args[n - 1]

      (0..(n - 2)).each do |i|
        @stack << args[ i ]
      end
    end

    # implemented in Rpl
    # push a copy of the element in stack level 2 onto the stack
    def over
      run( '2 pick' )
    end

    # drop first stack entry
    def drop
      run( '1 dropn' )
    end

    # drop 2 first stack entries
    def drop2
      run( '2 dropn' )
    end

    # duplicate first stack entry
    def dup
      run( '1 dupn' )
    end

    # duplicate 2 first stack entries
    def dup2
      run( '2 dupn' )
    end
  end
end