Class: BinData::Struct

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

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.

Direct Known Subclasses

Record

Defined Under Namespace

Classes: Snapshot

Constant Summary collapse

RESERVED =

These reserved words may not be used as field names

(::Hash.instance_methods.collect { |meth| meth.to_s } + 
%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} ).uniq

Instance Attribute Summary

Attributes inherited from Base

#parent

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Base

#==, accepted_parameters, #assign, #debug_name, default_parameters, #eval_parameter, #get_parameter, #has_parameter?, #inspect, mandatory_parameters, mutually_exclusive_parameters, #num_bytes, #offset, optional_parameters, #pretty_print, #read, read, #rel_offset, #snapshot, #to_binary_s, #to_s, #write

Constructor Details

#initialize(params = {}, parent = nil) ⇒ Struct

Returns a new instance of Struct.



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# File 'lib/bindata/struct.rb', line 143

def initialize(params = {}, parent = nil)
  super(params, parent)

  @field_names = get_parameter(:fields).field_names
  @field_objs  = []
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(symbol, *args, &block) ⇒ Object

:nodoc:



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# File 'lib/bindata/struct.rb', line 175

def method_missing(symbol, *args, &block) #:nodoc:
  obj = find_obj_for_name(symbol)
  if obj
    invoke_field(obj, symbol, args)
  else
    super
  end
end

Class Method Details

.sanitize_parameters!(params, sanitizer) ⇒ Object

:nodoc:



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# File 'lib/bindata/struct.rb', line 73

def sanitize_parameters!(params, sanitizer) #:nodoc:
  sanitize_endian(params, sanitizer)
  sanitize_fields(params, sanitizer)
  sanitize_hide(params, sanitizer)
end

Instance Method Details

#clear ⇒ Object

:nodoc:



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# File 'lib/bindata/struct.rb', line 150

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

#clear? ⇒ Boolean

:nodoc:

Returns:

  • (Boolean) 


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

def clear? #:nodoc:
  @field_objs.inject(true) { |all_clear, f| all_clear and (f.nil? or f.clear?) }
end

#debug_name_of(child) ⇒ Object

:nodoc:



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# File 'lib/bindata/struct.rb', line 184

def debug_name_of(child) #:nodoc:
  field_name = @field_names[find_index_of(child)]
  "#{debug_name}.#{field_name}"
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 161

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

#offset_of(child) ⇒ Object

:nodoc:



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# File 'lib/bindata/struct.rb', line 189

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

#respond_to?(symbol, include_private = false) ⇒ Boolean

:nodoc:

Returns:

  • (Boolean) 


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

def respond_to?(symbol, include_private = false) #:nodoc:
  super(symbol, include_private) ||
    field_names(true).include?(symbol.to_s.chomp("="))
end