Class: BinData::Primitive

Inherits:
BasePrimitive show all
Includes:
DSLMixin
Defined in:
lib/bindata/primitive.rb

Overview

A Primitive is a declarative way to define a new BinData data type. The data type must contain a primitive value only, i.e numbers or strings. For new data types that contain multiple values see BinData::Record.

To define a new data type, set fields as if for Record and add a #get and #set method to extract / convert the data between the fields and the #value of the object.

require 'bindata'

class PascalString < BinData::Primitive
  uint8  :len,  :value => lambda { data.length }
  string :data, :read_length => :len

  def get
    self.data
  end

  def set(v)
    self.data = v
  end
end

ps = PascalString.new(:initial_value => "hello")
ps.to_binary_s #=> "\005hello"
ps.read("\003abcde")
ps.value #=> "abc"

# Unsigned 24 bit big endian integer
class Uint24be < BinData::Primitive
  uint8 :byte1
  uint8 :byte2
  uint8 :byte3

  def get
    (self.byte1 << 16) | (self.byte2 << 8) | self.byte3
  end

  def set(v)
    v = 0 if v < 0
    v = 0xffffff if v > 0xffffff

    self.byte1 = (v >> 16) & 0xff
    self.byte2 = (v >>  8) & 0xff
    self.byte3 =  v        & 0xff
  end
end

u24 = Uint24be.new
u24.read("\x12\x34\x56")
"0x%x" % u24.value #=> 0x123456

Parameters

Primitive objects accept all the parameters that BinData::BasePrimitive do.

Constant Summary

Constants included from DSLMixin

DSLMixin::BlockParsers

Instance Attribute Summary

Attributes inherited from Base

#parent

Class Method Summary collapse

Instance Method Summary collapse

Methods included from DSLMixin

included

Methods inherited from BasePrimitive

#clear, #clear?, #eql?, #hash, #respond_to?, #value, #value=

Methods inherited from Base

#==, #assign, #clear, #clear?, #debug_name, #eval_parameter, #get_parameter, #has_parameter?, #inspect, #num_bytes, #offset, #offset_of, #pretty_print, #read, read, register, register_class, register_self, register_subclasses, #rel_offset, #snapshot, #to_binary_s, #to_s, #write

Methods included from AcceptedParametersMixin

included

Constructor Details

#initialize(parameters = {}, parent = nil) ⇒ Primitive

Returns a new instance of Primitive.



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# File 'lib/bindata/primitive.rb', line 76

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

  @struct = BinData::Struct.new(get_parameter(:struct_params), self)
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/primitive.rb', line 82

def method_missing(symbol, *args, &block) #:nodoc:
  @struct.__send__(symbol, *args, &block)
end

Class Method Details

.sanitize_parameters!(params, sanitizer) ⇒ Object

:nodoc:



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# File 'lib/bindata/primitive.rb', line 69

def sanitize_parameters!(params, sanitizer) #:nodoc:
  params[:struct_params] = sanitizer.create_sanitized_params(to_struct_params, BinData::Struct)
end

Instance Method Details

#debug_name_of(child) ⇒ Object

:nodoc:



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# File 'lib/bindata/primitive.rb', line 86

def debug_name_of(child) #:nodoc:
  debug_name + "-internal-"
end