Run-length encoding

# title: Run-length encoding
# source: https://rosettacode.org/wiki/Run-length_encoding
# category: Rosetta Code
# difficulty: Easy
# summary: Encode and decode a short sample string with classic run-length encoding.
# tags: popular, strings, compression, loops
# vibe: 0.2

def encode(text)
  if text == ""
    return []
  end

  output = []
  current = text.slice(0)
  count = 1
  index = 1

  while index < text.length
    char = text.slice(index)

    if char == current
      count = count + 1
    else
      output = output.push({
        char: current,
        count: count
      })
      current = char
      count = 1
    end

    index = index + 1
  end

  output.push({
    char: current,
    count: count
  })
end

def decode(runs)
  output = ""
  index = 0

  while index < runs.size
    entry = runs[index]
    entry[:count].times do
      output = output + entry[:char]
    end

    index = index + 1
  end

  output
end

def run
  sample = "AAABBCCCC"
  encoded = encode(sample)
  {
    sample: sample,
    encoded: encoded,
    decoded: decode(encoded)
  }
end