Class: Snow::CStruct::Builder

Inherits:
Object
  • Object
show all
Defined in:
lib/snow-data/c_struct/builder.rb

Constant Summary collapse

@@defined_types = 
Set.new

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(&block) ⇒ Builder

call-seq:

new => Builder
new { ... } => Builder

In either form, a new Builder is allocated and returned. If a block is given, then it will be instance_exec’d, allowing you to easily call any declaration methods on the builder instance.



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# File 'lib/snow-data/c_struct/builder.rb', line 19

def initialize(&block)
  @members = []
  @last_offset = 0
  instance_exec(&block) if block_given?
end

Class Method Details

.flush_type_methods! ⇒ Object

call-seq:

flush_type_methods! => self

Defines methods for declaring members of any recognized CStruct type, including aliases.



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# File 'lib/snow-data/c_struct/builder.rb', line 43

def self.flush_type_methods!
  ::Snow::CStruct::SIZES.each do |type_name, type_size|
    next if @@defined_types.include?(type_name)

    method_name = type_name.to_s
    first_char = method_name[0]
    case
    when first_char >= ?A && first_char <= ?Z
      method_name[0] = first_char.downcase
    when first_char >= ?0 && first_char <= ?9
      method_name[0] = "_#{first_char}"
    end
    method_name = method_name.to_sym

    __send__(:define_method, method_name) do | name, lengths = 1, align: nil |
      name = name.to_sym

      length = case lengths
               when Integer, Fixnum then lengths
               when Array then lengths.reduce(:*)
               else lengths.to_i
               end
      raise "Invalid length for member #{name}: must be >= 1" if length < 1

      size = length * type_size

      align = (align || ::Snow::CStruct::ALIGNMENTS[type_name]).to_i
      raise "Nil alignment for type #{type_name}" if align.nil?

      last_offset = instance_variable_get(:@last_offset)
      offset = ::Snow::Memory.align_size(last_offset, align)
      last_offset = offset + size

      member_info = ::Snow::CStruct::StructMemberInfo[
        name, type_name, size, length, align, offset]

      instance_variable_set(:@last_offset, last_offset)
      instance_variable_get(:@members).push(member_info.freeze)
    end # define_method(type_name)

    @@defined_types.add(type_name)

  end # SIZES.each

  ::Snow::CStruct::TYPE_ALIASES.each { |short, long|
    __send__(:alias_method, short, long)
  }

  self
end

Instance Method Details

#member_info ⇒ Object

call-seq:

member_info => [StructMemberInfo]

Returns the StructMemberInfo array for the builder. You should copy this if you need to modify it, and the same goes for its elements.



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# File 'lib/snow-data/c_struct/builder.rb', line 32

def member_info
  @members
end