Class: BinaryCodec::BinaryParser

Inherits:
Object
  • Object
show all
Defined in:
lib/binary-codec/serdes/binary_parser.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(hex_bytes = '') ⇒ BinaryParser 



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# File 'lib/binary-codec/serdes/binary_parser.rb', line 9

def initialize(hex_bytes = '')
  @bytes = hex_to_bytes(hex_bytes)
  @definitions = Definitions.instance
end

Instance Attribute Details

#definitions ⇒ Object (readonly)

Returns the value of attribute definitions.



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# File 'lib/binary-codec/serdes/binary_parser.rb', line 7

def definitions
  @definitions
end

Instance Method Details

#end?(custom_end = nil) ⇒ Boolean

Checks if the end of the stream has been reached.



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# File 'lib/binary-codec/serdes/binary_parser.rb', line 82

def end?(custom_end = nil)
  length = @bytes.length
  length == 0 || (!custom_end.nil? && length <= custom_end)
end

#peek ⇒ Integer

Returns the first byte in the stream without consuming it.



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# File 'lib/binary-codec/serdes/binary_parser.rb', line 16

def peek
  if @bytes.empty?
    raise StandardError.new
  end
  @bytes[0]
end

#read(n) ⇒ Array<Integer>

Reads n bytes from the stream.



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# File 'lib/binary-codec/serdes/binary_parser.rb', line 35

def read(n)
  if n > @bytes.length
    raise StandardError.new('End of byte stream reached')
  end

  slice = @bytes[0, n]
  skip(n)
  slice
end

#read_field ⇒ FieldInstance

Reads a field instance from the stream.



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# File 'lib/binary-codec/serdes/binary_parser.rb', line 137

def read_field
  field_header = read_field_header
  field_name = @definitions.get_field_name_from_header(field_header)

  @definitions.get_field_instance(field_name)
end

#read_field_header ⇒ FieldHeader

Reads a field header from the stream.



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# File 'lib/binary-codec/serdes/binary_parser.rb', line 113

def read_field_header
  type = read_uint8
  nth = type & 15
  type >>= 4

  if type == 0
    type = read_uint8
    if type == 0 || type < 16
      raise StandardError.new("Cannot read FieldOrdinal, type_code #{type} out of range")
    end
  end

  if nth == 0
    nth = read_uint8
    if nth == 0 || nth < 16
      raise StandardError.new("Cannot read FieldOrdinal, field_code #{nth} out of range")
    end
  end

  FieldHeader.new(type: type, nth: nth) # (type << 16) | nth for read_field_ordinal
end

#read_field_value(field) ⇒ SerializedType

Reads the value of a specific field from the stream.



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# File 'lib/binary-codec/serdes/binary_parser.rb', line 161

def read_field_value(field)
  type = SerializedType.get_type_by_name(field.type)

  if type.nil?
    raise StandardError.new("unsupported: (#{field.name}, #{field.type.name})")
  end

  size_hint = field.is_variable_length_encoded ? read_variable_length_length : nil
  value = type.from_parser(self, size_hint)

  if value.nil?
    raise StandardError.new("from_parser for (#{field.name}, #{field.type.name}) -> nil")
  end

  value
end

#read_type(type) ⇒ SerializedType

Reads a value of the specified type from the stream.



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# File 'lib/binary-codec/serdes/binary_parser.rb', line 147

def read_type(type)
  type.from_parser(self)
end

#read_uint16 ⇒ Integer

Reads a 2-byte unsigned integer.



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# File 'lib/binary-codec/serdes/binary_parser.rb', line 63

def read_uint16
  read_uint_n(2)
end

#read_uint32 ⇒ Integer

Reads a 4-byte unsigned integer.



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# File 'lib/binary-codec/serdes/binary_parser.rb', line 69

def read_uint32
  read_uint_n(4)
end

#read_uint8 ⇒ Integer

Reads a 1-byte unsigned integer.



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# File 'lib/binary-codec/serdes/binary_parser.rb', line 57

def read_uint8
  read_uint_n(1)
end

#read_uint_n(n) ⇒ Integer

Reads n bytes and converts them to an unsigned integer.



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# File 'lib/binary-codec/serdes/binary_parser.rb', line 48

def read_uint_n(n)
  if n <= 0 || n > 4
    raise StandardError.new('invalid n')
  end
  read(n).reduce(0) { |a, b| (a << 8) | b }
end

#read_variable_length ⇒ Array<Integer>

Reads variable length data from the stream.



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# File 'lib/binary-codec/serdes/binary_parser.rb', line 89

def read_variable_length
  read(read_variable_length_length)
end

#read_variable_length_length ⇒ Integer

Reads the length of a variable length data segment.



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# File 'lib/binary-codec/serdes/binary_parser.rb', line 95

def read_variable_length_length
  b1 = read_uint8
  if b1 <= 192
    b1
  elsif b1 <= 240
    b2 = read_uint8
    193 + (b1 - 193) * 256 + b2
  elsif b1 <= 254
    b2 = read_uint8
    b3 = read_uint8
    12481 + (b1 - 241) * 65536 + b2 * 256 + b3
  else
    raise StandardError.new('Invalid variable length indicator')
  end
end

#size ⇒ Integer

Returns the number of bytes remaining in the stream.



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# File 'lib/binary-codec/serdes/binary_parser.rb', line 75

def size
  @bytes.length
end

#skip(n) ⇒ Object

Consumes n bytes from the stream.



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# File 'lib/binary-codec/serdes/binary_parser.rb', line 25

def skip(n)
  if n > @bytes.length
    raise StandardError.new
  end
  @bytes = @bytes[n..-1]
end

#type_for_field(field) ⇒ Class

Returns the associated type for a given field.



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# File 'lib/binary-codec/serdes/binary_parser.rb', line 154

def type_for_field(field)
  field.associated_type
end