class BinData::Struct

A Struct is an ordered collection of named data objects.

require 'bindata'

class Tuple < BinData::Record
  int8  :x
  int8  :y
  int8  :z
end

obj = BinData::Struct.new(hide: :a,
                          fields: [ [:int32le, :a],
                                    [:int16le, :b],
                                    [:tuple, :s] ])
obj.field_names   =># [:b, :s]

Parameters

Parameters may be provided at initialisation to control the behaviour of an object. These params are:

:fields: An array specifying the fields for this struct. Each element of the array is of the form [type, name, params]. Type is a symbol representing a registered type. Name is the name of this field. Params is an optional hash of parameters to pass to this field when instantiating it. If name is “” or nil, then that field is anonymous and behaves as a hidden field.
:hide: A list of the names of fields that are to be hidden from the outside world. Hidden fields don’t appear in snapshot or field_names but are still accessible by name.
:endian: Either :little or :big. This specifies the default endian of any numerics in this struct, or in any nested data objects.
:search_prefix: Allows abbreviated type names. If a type is unrecognised, then each prefix is applied until a match is found.

Field Parameters

Fields may have have extra parameters as listed below:

:onlyif: Used to indicate a data object is optional. if false, this object will not be included in any calls to read, write, num_bytes or snapshot.
:byte_align: This field’s rel_offset must be a multiple of :byte_align.

Constants

RESERVED: These reserved words may not be used as field names

Public Instance Methods

[](key) click to toggle source

# File lib/bindata/struct.rb, line 152
def [](key)
  find_obj_for_name(key)
end

[]=(key, value) click to toggle source

# File lib/bindata/struct.rb, line 156
def []=(key, value)
  obj = find_obj_for_name(key)
  if obj
    obj.assign(value)
  end
end

assign(val) click to toggle source

# File lib/bindata/struct.rb, line 100
def assign(val)
  clear
  assign_fields(val)
end

do_write(io) click to toggle source

# File lib/bindata/struct.rb, line 142
def do_write(io) #:nodoc
  instantiate_all_objs
  @field_objs.each { |f| f.do_write(io) if include_obj?(f) }
end

each_pair() { |name, find_obj_for_name(name)| ... } click to toggle source

# File lib/bindata/struct.rb, line 167
def each_pair
  @field_names.compact.each do |name|
    yield [name, find_obj_for_name(name)]
  end
end

field_names(include_hidden = false) click to toggle source

Returns a list of the names of all fields accessible through this object. include_hidden specifies whether to include hidden names in the listing.

# File lib/bindata/struct.rb, line 117
def field_names(include_hidden = false)
  if include_hidden
    @field_names.compact
  else
    hidden = get_parameter(:hide) || []
    @field_names.compact - hidden
  end
end

has_key?(key) click to toggle source

has_key? is deprecated

Alias for: key?

initialize_instance() click to toggle source

# File lib/bindata/struct.rb, line 88
def initialize_instance
  @field_objs = []
end

initialize_shared_instance() click to toggle source

# File lib/bindata/struct.rb, line 80
def initialize_shared_instance
  fields = get_parameter(:fields)
  @field_names = fields.field_names.freeze
  extend ByteAlignPlugin if fields.any_field_has_parameter?(:byte_align)
  define_field_accessors
  super
end

key?(key) click to toggle source

# File lib/bindata/struct.rb, line 163
def key?(key)
  @field_names.index(base_field_name(key))
end

Also aliased as: has_key?

snapshot() click to toggle source

# File lib/bindata/struct.rb, line 105
def snapshot
  snapshot = Snapshot.new
  field_names.each do |name|
    obj = find_obj_for_name(name)
    snapshot[name] = obj.snapshot if include_obj?(obj)
  end
  snapshot
end