Simplest QIF Parser

qif_parser.rb

# require 'date'
require 'pathname'

# returns an array of transactions, assuming the whole file relates to one account
def parse_qif_file(f)
  qif_text = Pathname.new(f).readlines.drop_while { _1.start_with? '!' }.join
  parse_qif(qif_text)
end

def parse_qif(text)
  # see the file format in https://en.wikipedia.org/wiki/Quicken_Interchange_Format
  transactions = text.split("^").map(&:strip).map { parse_qif_transaction(_1) }
end

def parse_qif_transaction(text)
  text.lines.map(&:strip).reduce({}) do |transaction, line|
    code = line[0]
    value = line[1..]
    key =
      case code
      when 'D' then :date
      when 'P' then :payee
      when 'T', 'U', '$' then :amount
      end
    transaction[key] = value
    transaction
  end
end