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Filename : closure.rb
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# frozen_string_literal: true
module Fiddle
  class Closure
    class << self
      # Create a new closure. If a block is given, the created closure
      # is automatically freed after the given block is executed.
      #
      # The all given arguments are passed to Fiddle::Closure.new. So
      # using this method without block equals to Fiddle::Closure.new.
      #
      # == Example
      #
      #   Fiddle::Closure.create(TYPE_INT, [TYPE_INT]) do |closure|
      #     # closure is freed automatically when this block is finished.
      #   end
      def create(*args)
        if block_given?
          closure = new(*args)
          begin
            yield(closure)
          ensure
            closure.free
          end
        else
          new(*args)
        end
      end
    end

    # the C type of the return of the FFI closure
    attr_reader :ctype

    # arguments of the FFI closure
    attr_reader :args

    # Extends Fiddle::Closure to allow for building the closure in a block
    class BlockCaller < Fiddle::Closure

      # == Description
      #
      # Construct a new BlockCaller object.
      #
      # * +ctype+ is the C type to be returned
      # * +args+ are passed the callback
      # * +abi+ is the abi of the closure
      #
      # If there is an error in preparing the +ffi_cif+ or +ffi_prep_closure+,
      # then a RuntimeError will be raised.
      #
      # == Example
      #
      #   include Fiddle
      #
      #   cb = Closure::BlockCaller.new(TYPE_INT, [TYPE_INT]) do |one|
      #     one
      #   end
      #
      #   func = Function.new(cb, [TYPE_INT], TYPE_INT)
      #
      def initialize ctype, args, abi = Fiddle::Function::DEFAULT, &block
        super(ctype, args, abi)
        @block = block
      end

      # Calls the constructed BlockCaller, with +args+
      #
      # For an example see Fiddle::Closure::BlockCaller.new
      #
      def call *args
        @block.call(*args)
      end
    end
  end
end