Class: Protobuf::Decoder

Inherits:
Object
  • Object
show all
Defined in:
lib/protobuf/decoder.rb

Class Method Summary collapse

Class Method Details

.decode_each_field(stream, &block) ⇒ Object

Read bytes from +stream+ and pass to +message+ object.



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# File 'lib/protobuf/decoder.rb', line 8

def self.decode_each_field(stream, &block)
  until stream.eof?
    tag, bytes = read_field(stream)
    block.call(tag, bytes)
  end
end

.read_field(stream) ⇒ Object 



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# File 'lib/protobuf/decoder.rb', line 15

def self.read_field(stream)
  tag, wire_type = read_key(stream)
  bytes = case wire_type
          when ::Protobuf::WireType::VARINT then
            read_varint(stream)
          when ::Protobuf::WireType::FIXED64 then
            read_fixed64(stream)
          when ::Protobuf::WireType::LENGTH_DELIMITED then
            read_length_delimited(stream)
          when ::Protobuf::WireType::FIXED32 then
            read_fixed32(stream)
          when ::Protobuf::WireType::START_GROUP then
            raise NotImplementedError, 'Group is deprecated.'
          when ::Protobuf::WireType::END_GROUP then
            raise NotImplementedError, 'Group is deprecated.'
          else
            raise InvalidWireType, wire_type
          end

  return tag, bytes
end

.read_fixed32(stream) ⇒ Object

Read 32-bit string value from +stream+.



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# File 'lib/protobuf/decoder.rb', line 38

def self.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/decoder.rb', line 43

def self.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/decoder.rb', line 48

def self.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/decoder.rb', line 56

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

.read_varint(stream) ⇒ Object

Read varint integer value from +stream+.



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# File 'lib/protobuf/decoder.rb', line 62

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