Word frequency

# title: Word frequency
# source: https://rosettacode.org/wiki/Word_frequency
# category: Rosetta Code
# difficulty: Intro
# summary: Count the frequency of normalized words in a short sample passage.
# tags: popular, strings, hashes, parsing
# vibe: 0.2

def letter?(char)
  (char >= "a" && char <= "z") || (char >= "A" && char <= "Z")
end

def word_counts(text)
  counts = {}
  current = ""
  index = 0

  while index < text.length
    char = text.slice(index)
    if letter?(char)
      current = current + char.downcase
    elsif current != ""
      counts[current] = counts.fetch(current, 0) + 1
      current = ""
    end
    index = index + 1
  end

  if current != ""
    counts[current] = counts.fetch(current, 0) + 1
  end

  counts
end

def run
  counts = word_counts("To be, or not to be: that is the question. To be or not?")
  rows = []
  rows = rows.push({ word: "to", count: counts.fetch("to", 0) })
  rows = rows.push({ word: "be", count: counts.fetch("be", 0) })
  rows = rows.push({ word: "not", count: counts.fetch("not", 0) })
  rows = rows.push({ word: "question", count: counts.fetch("question", 0) })
  rows
end