Crow Data Format Library in crystal-lang

Compact encoding for typed tabular data. Think of it as a binary CSV file. The encoding format is defined in the Crow Encoding Spec.

Features

• Uses protobuf encoding formats like varint, zigzag encoding
• Does not require compilation of proto definitions
• Fields (e.g. Columns) are defined inline
• Data can be sparse

Field class - describes a column

The application can refer to columns by IDs (like IPFIX) or Names (like a CSV file with header).

Field
  typeid : CrowType (TINT32, TSTRING, etc.)
  name : String
  id : UInt32
  subid : UInt32  # optional

Usage : Encoding - Column names

enc = Crow::Encoder.new io

enc.put "bob", "Name"
enc.put 23, "Age"
enc.put true, "Active"
enc.put_row_sep

Usage : Decoding

dec = Crow::Decoder.new io
loop do
  rowdata = dec.read_row
  break if rowdata.nil? || rowdata.empty?

  rowdata.each do |item|
    # item.value is actual value (of type String, Int32, etc.)
    # item.field if Field object with id, name of column
  end
end