Module: Protobuf::Decoder

Defined in:
lib/protobuf/message/decoder.rb

Constant Summary collapse

READ_METHODS = 
[
  :read_varint,           # 0: Varint
  :read_fixed64,          # 1: 64 bit
  :read_length_delimited, # 2: Length-delimited
  :read_start_group,      # 3: Start group
  :read_end_group,        # 4: End group
  :read_fixed32,          # 5: 32 bit
]

Class Method Summary collapse

Class Method Details

.decode(stream, message) ⇒ Object

Read bytes from stream and pass to message object.



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# File 'lib/protobuf/message/decoder.rb', line 20

def decode(stream, message)
  until stream.eof?
    tag, wire_type = read_key(stream)
    field = message.get_field_by_tag(tag)

    method = READ_METHODS[wire_type]
    raise InvalidWireType, "Unknown wire type: #{wire_type}" unless method
    value = send(method, stream)

    if field.nil?
      # ignore unknown field
    elsif field.repeated?
      array = message.__send__(field.name)
      if wire_type == WireType::LENGTH_DELIMITED && WireType::PACKABLE_TYPES.include?(field.wire_type)
        # packed
        s = StringIO.new(value)
        m = READ_METHODS[field.wire_type]
        until s.eof?
          array << field.decode(send(m, s))
        end
      else
        # non-packed
        array << field.decode(value)
      end
    else
      message.__send__("#{field.name}=", field.decode(value))
    end
  end
  message
end

.read_end_group(stream) ⇒ Object

Not implemented.

Raises:

  • (NotImplementedError) 


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# File 'lib/protobuf/message/decoder.rb', line 93

def read_end_group(stream)
  raise NotImplementedError, 'Group is deprecated.'
end

.read_fixed32(stream) ⇒ Object

Read 32-bit string value from stream.



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# File 'lib/protobuf/message/decoder.rb', line 72

def read_fixed32(stream)
  stream.read(4)
end

.read_fixed64(stream) ⇒ Object

Read 64-bit string value from stream.



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# File 'lib/protobuf/message/decoder.rb', line 77

def read_fixed64(stream)
  stream.read(8)
end

.read_key(stream) ⇒ Object

Read key pair (tag and wire-type) from stream.



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# File 'lib/protobuf/message/decoder.rb', line 52

def read_key(stream)
  bits = read_varint(stream)
  wire_type = bits & 0x07
  tag = bits >> 3
  [tag, wire_type]
end

.read_length_delimited(stream) ⇒ Object

Read length-delimited string value from stream.



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# File 'lib/protobuf/message/decoder.rb', line 82

def read_length_delimited(stream)
  value_length = read_varint(stream)
  stream.read(value_length)
end

.read_start_group(stream) ⇒ Object

Not implemented.

Raises:

  • (NotImplementedError) 


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# File 'lib/protobuf/message/decoder.rb', line 88

def read_start_group(stream)
  raise NotImplementedError, 'Group is deprecated.'
end

.read_varint(stream) ⇒ Object

Read varint integer value from stream.



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# File 'lib/protobuf/message/decoder.rb', line 60

def read_varint(stream)
  read_method = stream.respond_to?(:readbyte) ? :readbyte : :readchar
  value = index = 0
  begin
    byte = stream.__send__(read_method)
    value |= (byte & 0x7f) << (7 * index)
    index += 1
  end while (byte & 0x80).nonzero?
  value
end