Class: PackedModel::Base

Inherits:
Object
  • Object
show all
Defined in:
lib/packed_model/base.rb

Constant Summary collapse

@@valid_true_boolean_values = 
nil

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(values = nil) ⇒ Base

Returns a new instance of Base.



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# File 'lib/packed_model/base.rb', line 195

def initialize(values=nil)
  case values
  when String
    raise InvalidDataException.new("fixed width model expected #{self.bytesize} but got #{values.bytesize}") if self.fixed_width? && self.bytesize != values.bytesize
    self.unpack values
  when Hash
    @changed = true
    @values = []
    values.each do |k, v|
      send("#{k}=", v) if self.class.field_options(k)
    end
    fields.each do |options|
      next unless options[:fields]
      options[:fields].each do |field|
        send("#{field}=", values[field]) if values.has_key?(field)
      end
    end
    # set default values
    fields.each_with_index do |field, idx|
      @values[idx] ||= self.class.default_values[idx]
    end
  when NilClass
    @changed = true
    @values = self.class.default_values.dup
  else
    raise InvalidDataException.new("invalid values")
  end
end

Class Method Details

.add_unpack_callback(callback) ⇒ Object 



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# File 'lib/packed_model/base.rb', line 259

def self.add_unpack_callback(callback)
  @unpack_callbacks ||= []
  @unpack_callbacks << callback
end

.all_field_options ⇒ Object 



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# File 'lib/packed_model/base.rb', line 15

def self.all_field_options
  {}
end

.attribute(name, options = {}, &block) ⇒ Object 



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# File 'lib/packed_model/base.rb', line 39

def self.attribute(name, options={}, &block)
  options[:name] = name.to_sym
  raise "duplicate field name #{name}" if self.keys.include?(options[:name])
  options[:index] = self.fields.size
  options[:type] ||= :string
  case options[:type]
  when :string
    options[:strip] = true
    options[:null] = true
    options[:pack_directive] = 'Z*'
  when :integer, :int
    options[:default] ||= 0 # pack 'N' directive requires a value for an integer
    options[:bytesize] = 4
    options[:pack_directive] = 'N' # network byte order
  when :char
    options[:size] ||= 1
    options[:bytesize] = options[:size]
    options[:pack_directive] = "a#{options[:size]}"
  when :marker
    raise "missing value for marker" unless options[:value]
    options[:default] = options[:value]
    options[:bytesize] = 4
    options[:pack_directive] = 'N' # network byte order
    options[:unpack_callback] ||= create_marker_unpack_callback(options[:index], options[:value])
  when :custom
    raise "missing pack_directive for #{name}" unless options[:pack_directive]
  else
    raise "Unknown type #{options[:type]}"
  end

  add_unpack_callback(options[:unpack_callback]) if options[:unpack_callback].is_a?(Proc)
  add_unpack_callback(create_strip_unpack_callback(options[:index], options[:null])) if options[:strip]

  class_eval do
    attrs = self.fields << options
    ks = self.keys << options[:name]
    defaults = self.default_values << options[:default]
    ps = self.pack_string << options[:pack_directive]
    kopts = self.all_field_options.merge name.to_sym => options

    class << self; self end.send(:define_method, "fields") do
      attrs
    end
    class << self; self end.send(:define_method, "keys") do
      ks
    end
    class << self; self end.send(:define_method, "default_values") do
      defaults
    end
    class << self; self end.send(:define_method, "pack_string") do
      ps
    end
    class << self; self end.send(:define_method, "all_field_options") do
      kopts
    end

    if self.fixed_width? && options[:bytesize].nil?
      class << self; self end.send(:define_method, "fixed_width?") do
        false
      end
      class << self; self end.send(:define_method, "bytesize") do
        nil
      end
    end

    if self.fixed_width?
      bs = self.bytesize + options[:bytesize]
      class << self; self end.send(:define_method, "bytesize") do
        bs
      end
    end
  end

  method_src = <<-METHOD
    def #{name}
      @values[#{options[:index]}] || #{options[:default].inspect}
    end
    METHOD

  case options[:type]
  when :string, :char
    method_src << <<-METHOD
    def #{name}=(val)
      val = val.nil? ? nil : val.to_s
      @changed = @changed || @values[#{options[:index]}] != val
      @values[#{options[:index]}] = val
    end
    METHOD
  when :integer, :int
    method_src << <<-METHOD
    def #{name}=(val)
      val = val.nil? ? nil : val.to_i
      @changed = @changed || @values[#{options[:index]}] != val
      @values[#{options[:index]}] = val
    end
    METHOD
  when :custom
    if options[:filter].is_a?(Symbol) || options[:filter].is_a?(String)
      method_src << <<-METHOD
      def #{name}=(val)
        val = val.nil? ? nil : val.#{options[:filter]}
        @changed = @changed || @values[#{options[:index]}] != val
        @values[#{options[:index]}] = val
      end
      METHOD
    elsif options[:filter] ||= block
      method_src << <<-METHOD
      def #{name}=(val)
        val = val.nil? ? nil : self.class.field_options(#{name.inspect})[:filter].call(val)
        @changed = @changed || @values[#{options[:index]}] != val
        @values[#{options[:index]}] = val
      end
      METHOD
    else
      method_src << <<-METHOD
      def #{name}=(val)
        @changed = @changed || @values[#{options[:index]}] != val
        @values[#{options[:index]}] = val
      end
      METHOD
    end
  end

  self.class_eval method_src, __FILE__, __LINE__
end

.bit_vector(name, fields, options = {}) ⇒ Object 



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# File 'lib/packed_model/base.rb', line 170

def self.bit_vector(name, fields, options={})
  raise "too many fields for bit vecotr #{name}" if fields.size > 32

  self.attribute name, {:type => :integer, :fields => fields}.merge(options)

  name_equals = "#{name}="

  fields.each_with_index do |fld, idx|
    mask = 1 << idx
    neg_mask = 0xFFFFFFFF ^ mask

    define_method fld do
      (self.send(name) & mask) == mask
    end

    define_method "#{fld}=" do |val|
      if self.class.valid_true_boolean_values.include?(val)
        self.send(name_equals, self.send(name) | mask)
      else
        self.send(name_equals, self.send(name) & neg_mask)
      end
    end
  end
end

.field_index(key) ⇒ Object 



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# File 'lib/packed_model/base.rb', line 23

def self.field_index(key)
  field_options(key)[:index]
end

.field_options(key) ⇒ Object 



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# File 'lib/packed_model/base.rb', line 19

def self.field_options(key)
  all_field_options[key.to_sym]
end

.fields ⇒ Object 



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# File 'lib/packed_model/base.rb', line 3

def self.fields
  []
end

.fixed_width? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/packed_model/base.rb', line 31

def self.fixed_width?
  true
end

.keys ⇒ Object 



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# File 'lib/packed_model/base.rb', line 11

def self.keys
  []
end

.unpack_callbacks ⇒ Object 



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# File 'lib/packed_model/base.rb', line 264

def self.unpack_callbacks
  @unpack_callbacks
end

.valid_true_boolean_values ⇒ Object 



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# File 'lib/packed_model/base.rb', line 166

def self.valid_true_boolean_values
  @@valid_true_boolean_values ||= [true, 1, '1', 'true', 'on', 'yes']
end

Instance Method Details

#bytesize ⇒ Object 



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# File 'lib/packed_model/base.rb', line 249

def bytesize
  self.class.fixed_width? ? self.class.bytesize : (@bytesize ||= self.pack.bytesize)
end

#changed! ⇒ Object 



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# File 'lib/packed_model/base.rb', line 232

def changed!
  @changed = true
end

#changed? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/packed_model/base.rb', line 228

def changed?
  !! @changed
end

#fields ⇒ Object 



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# File 'lib/packed_model/base.rb', line 7

def fields
  self.class.fields
end

#fixed_width? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/packed_model/base.rb', line 35

def fixed_width?
  self.class.fixed_width?
end

#keys ⇒ Object 



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# File 'lib/packed_model/base.rb', line 27

def keys
  self.class.keys
end

#not_changed! ⇒ Object 



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# File 'lib/packed_model/base.rb', line 236

def not_changed!
  @changed = false
end

#pack ⇒ Object 



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# File 'lib/packed_model/base.rb', line 245

def pack
  @values.pack self.class.pack_string
end

#size ⇒ Object 



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# File 'lib/packed_model/base.rb', line 252

def bytesize
  self.class.fixed_width? ? self.class.bytesize : (@bytesize ||= self.pack.bytesize)
end

#to_hash ⇒ Object Also known as: to_h 



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# File 'lib/packed_model/base.rb', line 240

def to_hash
  Hash[self.keys.zip @values]
end

#unpack(str) ⇒ Object 



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# File 'lib/packed_model/base.rb', line 254

def unpack(str)
  @values = str.unpack(self.class.pack_string)
  self.unpack_callbacks.each { |c| c.call self } if self.unpack_callbacks
end

#unpack_callbacks ⇒ Object 



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# File 'lib/packed_model/base.rb', line 268

def unpack_callbacks
  self.class.unpack_callbacks
end

#values ⇒ Object 



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# File 'lib/packed_model/base.rb', line 224

def values
  @values
end