class ActionDispatch::Http::ParameterFilter::CompiledFilter

def self.compile(filters)
  return lambda { |params| params.dup } if filters.empty?
  strings, regexps, blocks = [], [], []
  filters.each do |item|
    case item
    when Proc
      blocks << item
    when Regexp
      regexps << item
    else
      strings << Regexp.escape(item.to_s)
    end
  end
  deep_regexps, regexps = regexps.partition { |r| r.to_s.include?("\\.".freeze) }
  deep_strings, strings = strings.partition { |s| s.include?("\\.".freeze) }
  regexps << Regexp.new(strings.join('|'.freeze), true) unless strings.empty?
  deep_regexps << Regexp.new(deep_strings.join('|'.freeze), true) unless deep_strings.empty?
  new regexps, deep_regexps, blocks
end

def call(original_params, parents = [])
  filtered_params = {}
  original_params.each do |key, value|
    parents.push(key) if deep_regexps
    if regexps.any? { |r| key =~ r }
      value = FILTERED
    elsif deep_regexps && (joined = parents.join('.')) && deep_regexps.any? { |r| joined =~ r }
      value = FILTERED
    elsif value.is_a?(Hash)
      value = call(value, parents)
    elsif value.is_a?(Array)
      value = value.map { |v| v.is_a?(Hash) ? call(v, parents) : v }
    elsif blocks.any?
      key = key.dup if key.duplicable?
      value = value.dup if value.duplicable?
      blocks.each { |b| b.call(key, value) }
    end
    parents.pop if deep_regexps
    filtered_params[key] = value
  end
  filtered_params
end

def initialize(regexps, deep_regexps, blocks)
  @regexps = regexps
  @deep_regexps = deep_regexps.any? ? deep_regexps : nil
  @blocks  = blocks
end