Class: PropertyList::BinaryGenerator

Inherits:
Object
  • Object
show all
Includes:
BinaryMarkers
Defined in:
lib/property-list/binary_generator.rb

Overview

Modified from:

https://github.com/jarib/plist/blob/master/lib/plist/binary.rb

With improved performance

Defined Under Namespace

Classes: Collection

Constant Summary collapse

V0_MAGIC = 
"bplist00".force_encoding('binary').freeze
V1_MAGIC = 
"bplist10".force_encoding('binary').freeze
TAIL_PADDING = 
"\0\0\0\0\0\0".force_encoding('binary').freeze

Constants included from BinaryMarkers

PropertyList::BinaryMarkers::MARKER_ARRAY, PropertyList::BinaryMarkers::MARKER_ASCII_STRING, PropertyList::BinaryMarkers::MARKER_DATA, PropertyList::BinaryMarkers::MARKER_DATE, PropertyList::BinaryMarkers::MARKER_DICT, PropertyList::BinaryMarkers::MARKER_FALSE, PropertyList::BinaryMarkers::MARKER_FILL, PropertyList::BinaryMarkers::MARKER_INT, PropertyList::BinaryMarkers::MARKER_NO_BASE_URL, PropertyList::BinaryMarkers::MARKER_NULL, PropertyList::BinaryMarkers::MARKER_ORD_SET, PropertyList::BinaryMarkers::MARKER_REAL, PropertyList::BinaryMarkers::MARKER_SET, PropertyList::BinaryMarkers::MARKER_TRUE, PropertyList::BinaryMarkers::MARKER_UID, PropertyList::BinaryMarkers::MARKER_UTF16BE_STRING, PropertyList::BinaryMarkers::MARKER_UTF8_STRING, PropertyList::BinaryMarkers::MARKER_UUID, PropertyList::BinaryMarkers::MARKER_WITH_BASE_URL, PropertyList::BinaryMarkers::TIME_INTERVAL_SINCE_1970

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(opts) ⇒ BinaryGenerator

Returns a new instance of BinaryGenerator.



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# File 'lib/property-list/binary_generator.rb', line 25

def initialize opts
  @output = []
  @offset = 0
  @objs = []
  @ref_size = 0
end

Instance Attribute Details

#output ⇒ Object (readonly)

Returns the value of attribute output.



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# File 'lib/property-list/binary_generator.rb', line 31

def output
  @output
end

Instance Method Details

#add_output(data) ⇒ Object 



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# File 'lib/property-list/binary_generator.rb', line 111

def add_output data
  @output << data
  @offset += data.bytesize
end

#binary_integer(i, num_bytes) ⇒ Object

Packs an integer i into its binary representation in the specified number of bytes. Byte order is big-endian. Negative integers cannot be stored in 1, 2, or 4 bytes.



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# File 'lib/property-list/binary_generator.rb', line 223

def binary_integer i, num_bytes
  if i < 0 && num_bytes < 8
    raise ArgumentError, "negative integers require 8 or 16 bytes of storage"
  end
  case num_bytes
  when 1
    add_output pack([i], "C")
  when 2
    add_output pack([i], "n")
  when 4
    add_output pack([i], "N")
  when 8
    add_output pack([i], "q>")
  when 16
    # TODO verify 128 bit integer encoding
    if i < 0
      i = 0xffff_ffff_ffff_ffff_ffff_ffff_ffff_ffff ^ i.abs + 1
    end
    add_output pack([i >> 64, i & 0xffff_ffff_ffff_ffff], "q>2")
  else
    raise ArgumentError, "num_bytes must be 1, 2, 4, 8, or 16"
  end
end

#binary_marker(marker, size) ⇒ Object 



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# File 'lib/property-list/binary_generator.rb', line 177

def binary_marker marker, size
  if size < 15
    add_output chr(marker | size)
  else
    add_output chr(marker | 0xf)
    binary_object size
  end
end

#binary_object(obj, ref_byte_size = 4) ⇒ Object 



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# File 'lib/property-list/binary_generator.rb', line 116

def binary_object obj, ref_byte_size = 4
  case obj
  when Symbol
    binary_string obj.to_s
  when String
    binary_string obj
  when Float
    add_output pack([(MARKER_REAL | 3), obj], "CG")
  when Integer
    nbytes = min_byte_size obj
    size_bits = { 1 => 0, 2 => 1, 4 => 2, 8 => 3, 16 => 4 }[nbytes]
    add_output chr(MARKER_INT | size_bits)
    binary_integer obj, nbytes
  when TrueClass
    add_output chr(MARKER_TRUE)
  when FalseClass
    add_output chr(MARKER_FALSE)
  when Time
    add_output pack([MARKER_DATE, obj.to_f - TIME_INTERVAL_SINCE_1970], "CG")
  when Date # also covers DateTime
    add_output pack([MARKER_DATE, obj.to_time.to_f - TIME_INTERVAL_SINCE_1970], "CG")
  when StringIO
    data = obj.string.force_encoding('binary') # NOTE StringIO.binmode doesn't work in <2.0.0 & rbx
    binary_marker MARKER_DATA, data.bytesize
    add_output data
  when IO
    obj.rewind
    obj.binmode
    data = obj.read
    binary_marker MARKER_DATA, data.bytesize
    add_output data
  when Collection
    binary_marker obj.marker, obj.size
    obj.refs.each do |i|
      binary_integer i, ref_byte_size
    end
  when Uid
    # Encoding is as integers, except values are unsigned.
    nbytes = min_byte_size obj.uid
    size_bits = { 1 => 0, 2 => 1, 4 => 2, 8 => 3, 16 => 4 }[nbytes]
    add_output chr(MARKER_UID | size_bits)
    binary_integer obj.uid, nbytes

  ## the following are v1x data types ##

  when Uuid
    @v1 = true
    data = pack([obj.uuid], 'H*')
    add_output chr(MARKER_UUID)
    add_output data
  when Url
    @v1 = true
    binary_url obj
  when NilClass
    @v1 = true
    add_output chr(MARKER_NULL)
  else
    raise UnsupportedTypeError, obj.class.to_s
  end
end

#binary_string(obj) ⇒ Object 



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# File 'lib/property-list/binary_generator.rb', line 186

def binary_string obj
  if obj.encoding == Encoding.find('binary')
    binary_marker MARKER_ASCII_STRING, obj.bytesize
    add_output obj
  elsif obj.ascii_only?
    obj = obj.dup.force_encoding 'binary'
    binary_marker MARKER_ASCII_STRING, obj.bytesize
    add_output obj
  else
    data = obj.encode('utf-16be').force_encoding 'binary'
    cp_size = data.bytesize / 2
    binary_marker MARKER_UTF16BE_STRING, cp_size # TODO check if it works for 4 bytes
    add_output data
  end
end

#binary_url(obj) ⇒ Object 



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# File 'lib/property-list/binary_generator.rb', line 202

def binary_url obj
  if obj.url =~ /\A\w+:\/\//
    add_output chr(MARKER_WITH_BASE_URL)
  else
    add_output chr(MARKER_NO_BASE_URL)
  end
  binary_marker MARKER_ASCII_STRING, obj.url.bytesize
  add_output obj.url
end

#chr(c) ⇒ Object 



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# File 'lib/property-list/binary_generator.rb', line 212

def chr c
  c.chr.force_encoding 'binary'
end

#flatten(obj) ⇒ Object 



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# File 'lib/property-list/binary_generator.rb', line 63

def flatten obj
  @ref_size += 1

  case obj
  when Array
    refs = []
    @objs << Collection[MARKER_ARRAY, obj.size, refs]
    obj.each do |e|
      refs << @ref_size
      flatten e
    end

  when Set
    @v1 = true
    refs = []
    @objs << Collection[MARKER_SET, obj.size, refs]
    obj.each do |e|
      refs << @ref_size
      flatten e
    end

  when Hash
    refs = []
    @objs << Collection[MARKER_DICT, obj.size, refs]
    obj.each do |e, _|
      refs << @ref_size
      flatten e
    end
    obj.each do |_, e|
      refs << @ref_size
      flatten e
    end

  when OrdSet
    @v1 = true
    refs = []
    elements = obj.elements
    @objs << Collection[MARKER_ORD_SET, elements.size, refs]
    elements.each do |e|
      refs << @ref_size
      flatten e
    end

  else
    @objs << obj
  end
end

#generate(obj) ⇒ Object 



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# File 'lib/property-list/binary_generator.rb', line 33

def generate obj
  flatten obj
  ref_byte_size = min_byte_size @ref_size - 1

  add_output V0_MAGIC
  offset_table = []
  @objs.each do |o|
    offset_table << @offset
    binary_object o, ref_byte_size
  end

  if @v1
    @output[0] = V1_MAGIC
  end

  offset_table_addr = @offset
  offset_byte_size = min_byte_size @offset
  offset_table.each do |offset|
    binary_integer offset, offset_byte_size
  end

  add_output pack([
    TAIL_PADDING,
    offset_byte_size, ref_byte_size,
    @ref_size,
    0, # index of root object
    offset_table_addr
  ], "a*C2Q>3")
end

#min_byte_size(i) ⇒ Object

Determines the minimum number of bytes that is a power of two and can represent the integer i. Raises a RangeError if the number of bytes exceeds 16. Note that the property list format considers integers of 1, 2, and 4 bytes to be unsigned, while 8- and 16-byte integers are signed; thus negative integers will always require at least 8 bytes of storage.



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# File 'lib/property-list/binary_generator.rb', line 252

def min_byte_size i
  if i < 0
    i = i.abs - 1
  else
    if i <= 0xff
      return 1
    elsif i <= 0xffff
      return 2
    elsif i <= 0xffffffff
      return 4
    end
  end      
  if i <= 0x7fffffffffffffff
    8
  elsif i <= 0x7fffffffffffffffffffffffffffffff
    16
  else
    raise RangeError, "integer too big - exceeds 128 bits"
  end
end

#pack(objs, format) ⇒ Object 



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# File 'lib/property-list/binary_generator.rb', line 216

def pack objs, format
  objs.pack(format).force_encoding 'binary'
end