Class: BinData::Struct

Inherits:
Base
  • Object
show all
Defined in:
lib/bindata/struct.rb,
lib/bindata/warnings.rb

Overview

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.

Direct Known Subclasses

Record

Defined Under Namespace

Modules: ByteAlignPlugin Classes: Snapshot

Constant Summary collapse

RESERVED =

These reserved words may not be used as field names

Hash[*
(Hash.instance_methods +
 %w[alias and begin break case class def defined do else elsif
    end ensure false for if in module next nil not or redo
    rescue retry return self super then true undef unless until
    when while yield] +
 %w[array element index value] +
 %w[type initial_length read_until] +
 %w[fields endian search_prefix hide onlyif byte_align] +
 %w[choices selection copy_on_change] +
 %w[read_abs_offset struct_params])
.collect(&:to_sym)
.uniq.collect { |key| [key, true]

Instance Attribute Summary

Attributes inherited from Base

#parent

Instance Method Summary collapse

Methods inherited from Base

#==, #=~, #abs_offset, arg_processor, auto_call_delayed_io, bindata_name, #debug_name, #eval_parameter, #get_parameter, #has_parameter?, #initialize_with_warning, #inspect, #lazy_evaluator, #new, #num_bytes, #pretty_print, #read, read, register_subclasses, #rel_offset, #safe_respond_to?, #to_binary_s, #to_hex, #to_s, unregister_self, #write

Methods included from AcceptedParametersPlugin

#accepted_parameters, #default_parameters, #mandatory_parameters, #mutually_exclusive_parameters, #optional_parameters

Methods included from RegisterNamePlugin

included

Methods included from Framework

#bit_aligned?

Instance Method Details

#[](key) ⇒ Object 



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# File 'lib/bindata/struct.rb', line 154

def [](key)
  find_obj_for_name(key)
end

#[]=(key, value) ⇒ Object 



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# File 'lib/bindata/struct.rb', line 158

def []=(key, value)
  find_obj_for_name(key)&.assign(value)
end

#assign(val) ⇒ Object 



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# File 'lib/bindata/struct.rb', line 102

def assign(val)
  clear
  assign_fields(val)
end

#clear ⇒ Object

:nodoc:



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# File 'lib/bindata/struct.rb', line 94

def clear # :nodoc:
  @field_objs.each { |f| f.nil? || f.clear }
end

#clear? ⇒ Boolean

:nodoc:

Returns:

  • (Boolean) 


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# File 'lib/bindata/struct.rb', line 98

def clear? # :nodoc:
  @field_objs.all? { |f| f.nil? || f.clear? }
end

#debug_name_of(child) ⇒ Object

:nodoc:



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# File 'lib/bindata/struct.rb', line 128

def debug_name_of(child) # :nodoc:
  field_name = @field_names[find_index_of(child)]
  "#{debug_name}.#{field_name}"
end

#do_num_bytes ⇒ Object

:nodoc:



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# File 'lib/bindata/struct.rb', line 149

def do_num_bytes # :nodoc:
  instantiate_all_objs
  sum_num_bytes_for_all_fields
end

#do_read(io) ⇒ Object

:nodoc:



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# File 'lib/bindata/struct.rb', line 139

def do_read(io) # :nodoc:
  instantiate_all_objs
  @field_objs.each { |f| f.do_read(io) if include_obj_for_io?(f) }
end

#do_write(io) ⇒ Object

:nodoc:



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# File 'lib/bindata/struct.rb', line 144

def do_write(io) # :nodoc:
  instantiate_all_objs
  @field_objs.each { |f| f.do_write(io) if include_obj_for_io?(f) }
end

#each_pair(include_all = false) ⇒ Object

Calls the given block for each field_name-field_obj pair.

Does not include anonymous or hidden fields unless include_all is true.



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# File 'lib/bindata/struct.rb', line 170

def each_pair(include_all = false)
  instantiate_all_objs

  pairs = @field_names.zip(@field_objs).select do |name, _obj|
    name || include_all
  end

  if block_given?
    pairs.each { |el| yield(el) }
  else
    pairs.each
  end
end

#field_names(include_hidden = false) ⇒ Object

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



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# File 'lib/bindata/struct.rb', line 119

def field_names(include_hidden = false)
  if include_hidden
    @field_names.compact
  else
    hidden = get_parameter(:hide) || []
    @field_names.compact - hidden
  end
end

#initialize_instance ⇒ Object 



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# File 'lib/bindata/struct.rb', line 90

def initialize_instance
  @field_objs = []
end

#initialize_shared_instance ⇒ Object 



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# File 'lib/bindata/struct.rb', line 82

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) ⇒ Boolean Also known as: has_key?

Returns:

  • (Boolean) 


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# File 'lib/bindata/struct.rb', line 162

def key?(key)
  @field_names.index(base_field_name(key))
end

#offset_of(child) ⇒ Object

:nodoc:



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# File 'lib/bindata/struct.rb', line 133

def offset_of(child) # :nodoc:
  instantiate_all_objs
  sum = sum_num_bytes_below_index(find_index_of(child))
  child.bit_aligned? ? sum.floor : sum.ceil
end

#snapshot ⇒ Object 



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# File 'lib/bindata/struct.rb', line 107

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