Module: Contracts::DSL::ClassMethods

Defined in:
lib/ruby_contracts.rb

Instance Method Summary collapse

Instance Method Details

#__contract_failure!(name, message, result, *args) ⇒ Object

Raises:



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# File 'lib/ruby_contracts.rb', line 42

def __contract_failure!(name, message, result, *args)
  args.pop if args.last.kind_of?(Proc)
  raise Contracts::Error.new("#{self}##{name}(#{args.join ', '}) => #{result || "?"} ; #{message}.")
end

#__contracts_for(name, current_contracts = nil) ⇒ Object 



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# File 'lib/ruby_contracts.rb', line 27

def __contracts_for(name, current_contracts=nil)
  inherited_contracts = ancestors[1..-1].reduce(Contracts.empty_contracts) do |c, klass|
    ancestor_hash = klass.instance_variable_get('@__contracts_for') || {}
    c[:before] += ancestor_hash.has_key?(name) ? ancestor_hash[name][:before] : []
    c[:after] += ancestor_hash.has_key?(name) ? ancestor_hash[name][:after] : []
    c
  end
  current_contracts = @__contracts_for[name] || current_contracts || Contracts.empty_contracts

  contracts = Contracts.empty_contracts
  contracts[:before] = current_contracts[:before] + inherited_contracts[:before]
  contracts[:after] = current_contracts[:after] + inherited_contracts[:after]
  contracts
end

#__contracts_initialize ⇒ Object 



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# File 'lib/ruby_contracts.rb', line 22

def __contracts_initialize
  @__contracts = Contracts.empty_contracts
  @__contracts_for = {}
end

#inherited(subclass) ⇒ Object 



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# File 'lib/ruby_contracts.rb', line 17

def inherited(subclass)
  super
  subclass.__contracts_initialize
end

#method_added(name) ⇒ Object 



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# File 'lib/ruby_contracts.rb', line 60

def method_added(name)
  super

  return unless ENV['ENABLE_ASSERTION']
  return if @__contracts_for.has_key?(name)

  __contracts = @__contracts_for[name] ||= __contracts_for(name, @__contracts)
  @__contracts = Contracts.empty_contracts

  if !__contracts[:before].empty? || !__contracts[:after].empty?
    original_method_name = "#{name}__with_contracts"
    define_method(original_method_name, instance_method(name))

    count = 0
    before_contracts = __contracts[:before].reduce("") do |code, contract|
      type, *args = contract
      case type
      when :type
        classes = args[0]
        code << "if __args.size < #{classes.size} then\n"
        code << "  self.class.__contract_failure!('#{name}', \"need at least #{classes.size} arguments (%i given)\" % [__args.size], nil, *args)\n"
        code << "else\n"
        conditions = []
        classes.each_with_index{ |klass, i| conditions << "__args[#{i}].kind_of?(#{klass})" }
        code << "  if !(#{conditions.join(' && ')}) then\n"
        code << "    self.class.__contract_failure!('#{name}', 'input type error', nil, *__args)\n"
        code << "  end\n"
        code << "end\n"
        code

      when :params
        # Define a method that verify the assertion
        contract_method_name = "__verify_contract_#{name}_in_#{count = count + 1}"
        define_method(contract_method_name) { |*params| self.instance_exec(*params, &args[1]) }

        code << "if !#{contract_method_name}(*__args) then\n"
        code << "  self.class.__contract_failure!('#{name}', \"invalid precondition: #{args[0]}\", nil, *__args)\n"
        code << "end"
        code
      else
        code
      end
    end

    after_contracts = __contracts[:after].reduce("") do |code, contract|
      type, *args = contract
      case type
      when :type
        code << "if !result.kind_of?(#{args[0]}) then\n"
        code << "self.class.__contract_failure!(name, \"result must be a kind of '#{args[0]}' not '%s'\" % [result.class.to_s], result, *__args)\n"
        code << "end\n"
        code
      when :result
        # Define a method that verify the assertion
        contract_method_name = "__verify_contract_#{name}_out_#{count = count + 1}"
        define_method(contract_method_name) { |*params| self.instance_exec(*params, &args[1]) }

        code << "if !#{contract_method_name}(result, *__args) then\n"
        code << "  self.class.__contract_failure!('#{name}', \"invalid postcondition: #{args[0]}\", result, *__args)\n"
        code << "end"
        code
      else
        code
      end
    end

    method = "      def \#{name}(*args, &block)\n        __args = block.nil? ? args : args + [block]\n        \#{before_contracts}\n        result = \#{original_method_name}(*args, &block)\n        \#{after_contracts}\n        return result\n      end\n    EOM\n\n    class_eval method\n  end\nend\n"

#post(message = nil, &block) ⇒ Object 



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# File 'lib/ruby_contracts.rb', line 56

def post(message=nil, &block)
  @__contracts[:after] << [:result, message, block] if ENV['ENABLE_ASSERTION']
end

#pre(message = nil, &block) ⇒ Object 



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# File 'lib/ruby_contracts.rb', line 52

def pre(message=nil, &block)
  @__contracts[:before] << [:params, message, block] if ENV['ENABLE_ASSERTION']
end

#type(options) ⇒ Object 



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# File 'lib/ruby_contracts.rb', line 47

def type(options)
  @__contracts[:before] << [:type, options[:in]] if ENV['ENABLE_ASSERTION'] && options.has_key?(:in)
  @__contracts[:after] << [:type, options[:out]] if ENV['ENABLE_ASSERTION'] && options.has_key?(:out)
end