Class: Tros::IO::BinaryDecoder

Inherits:
Object
  • Object
show all
Defined in:
lib/tros/io.rb

Overview

FIXME(jmhodges) move validate to this module?

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(reader) ⇒ BinaryDecoder

Returns a new instance of BinaryDecoder.



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# File 'lib/tros/io.rb', line 41

def initialize(reader)
  @reader = reader
end

Instance Attribute Details

#reader ⇒ Object (readonly)

reader is an object on which we can call read, seek and tell.



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# File 'lib/tros/io.rb', line 40

def reader
  @reader
end

Instance Method Details

#byte! ⇒ Object 



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# File 'lib/tros/io.rb', line 45

def byte!
  @reader.readbyte
end

#read(len) ⇒ Object 



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# File 'lib/tros/io.rb', line 102

def read(len)
  # Read n bytes
  @reader.read(len)
end

#read_boolean ⇒ Object 



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# File 'lib/tros/io.rb', line 54

def read_boolean
  byte! == 1
end

#read_bytes ⇒ Object 



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# File 'lib/tros/io.rb', line 90

def read_bytes
  # Bytes are encoded as a long followed by that many bytes of
  # data.
  read(read_long)
end

#read_double ⇒ Object 



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# File 'lib/tros/io.rb', line 82

def read_double
  #  A double is written as 8 bytes.
  # The double is converted into a 64-bit integer using a method
  # equivalent to Java's doubleToLongBits and then encoded in
  # little-endian format.
  @reader.read(8).unpack('E')[0]
end

#read_float ⇒ Object 



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# File 'lib/tros/io.rb', line 74

def read_float
  # A float is written as 4 bytes.
  # The float is converted into a 32-bit integer using a method
  # equivalent to Java's floatToIntBits and then encoded in
  # little-endian format.
  @reader.read(4).unpack('e')[0]
end

#read_long ⇒ Object Also known as: read_int 



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# File 'lib/tros/io.rb', line 58

def read_long
  # int and long values are written using variable-length,
  # zig-zag coding.
  b = byte!
  n = b & 0x7F
  shift = 7
  while (b & 0x80) != 0
    b = byte!
    n |= (b & 0x7F) << shift
    shift += 7
  end
  (n >> 1) ^ -(n & 1)
end

#read_null ⇒ Object 



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# File 'lib/tros/io.rb', line 49

def read_null
  # null is written as zero byte's
  nil
end

#read_string ⇒ Object 



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# File 'lib/tros/io.rb', line 96

def read_string
  # A string is encoded as a long followed by that many bytes of
  # UTF-8 encoded character data.
  read_bytes.force_encoding("UTF-8")
end

#skip(n) ⇒ Object 



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# File 'lib/tros/io.rb', line 144

def skip(n)
  reader.seek(reader.tell() + n)
end

#skip_boolean ⇒ Object 



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# File 'lib/tros/io.rb', line 111

def skip_boolean
  skip(1)
end

#skip_bytes ⇒ Object 



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# File 'lib/tros/io.rb', line 136

def skip_bytes
  skip(read_long)
end

#skip_double ⇒ Object 



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# File 'lib/tros/io.rb', line 132

def skip_double
  skip(8)
end

#skip_float ⇒ Object 



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# File 'lib/tros/io.rb', line 128

def skip_float
  skip(4)
end

#skip_long ⇒ Object Also known as: skip_int 



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# File 'lib/tros/io.rb', line 119

def skip_long
  b = byte!
  while (b & 0x80) != 0
    b = byte!
  end
end

#skip_null ⇒ Object 



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# File 'lib/tros/io.rb', line 107

def skip_null
  nil
end

#skip_string ⇒ Object 



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# File 'lib/tros/io.rb', line 140

def skip_string
  skip_bytes
end