class Dry::Logic::RuleCompiler

def call(ast)
  ast.map { |node| visit(node) }
end

def initialize(predicates)
  @predicates = predicates
end

def visit(node)
  name, nodes = node
  send(:"visit_#{name}", nodes)
end

def visit_and(node)
  left, right = node
  visit(left) & visit(right)
end

def visit_attr(node)
  name, predicate = node
  Rule::Attr.new(visit(predicate), name: name)
end

def visit_check(node)
  name, predicate, keys = node
  Rule::Check.new(visit(predicate), name: name, keys: keys || [name])
end

def visit_each(node)
  Rule::Each.new(visit(node))
end

def visit_implication(node)
  left, right = node
  visit(left) > visit(right)
end

def visit_key(node)
  name, predicate = node
  Rule::Key.new(visit(predicate), name: name)
end

def visit_not(node)
  visit(node).negation
end

def visit_or(node)
  left, right = node
  visit(left) | visit(right)
end

def visit_predicate(node)
  name, args = node
  predicates[name].curry(*args)
end

def visit_set(node)
  Rule::Set.new(call(node))
end

def visit_val(node)
  Rule::Value.new(visit(node))
end

def visit_xor(node)
  left, right = node
  visit(left) ^ visit(right)
end