module SyntaxTree::Ternaryable

In order for an ‘if` or `unless` expression to be shortened to a ternary, there has to be one and only one consequent clause which is an Else. Both the body of the main node and the body of the Else node must have only one statement, and that statement must not be on the denied list of potential statements.

Public Class Methods

call(q, node) click to toggle source

# File lib/syntax_tree/node.rb, line 6256
def call(q, node)
  return false if ENV["STREE_FAST_FORMAT"] || q.disable_auto_ternary?

  # If this is a conditional inside of a parentheses as the only content,
  # then we don't want to transform it into a ternary. Presumably the user
  # wanted it to be an explicit conditional because there are parentheses
  # around it. So we'll just leave it in place.
  grandparent = q.grandparent
  if grandparent.is_a?(Paren) && (body = grandparent.contents.body) &&
       body.length == 1 && body.first == node
    return false
  end

  # Otherwise, we'll check the type of predicate. For certain nodes we
  # want to force it to not be a ternary, like if the predicate is an
  # assignment because it's hard to read.
  case node.predicate
  when Assign, Binary, Command, CommandCall, MAssign, OpAssign
    return false
  when Not
    return false unless node.predicate.parentheses?
  end

  # If there's no Else, then this can't be represented as a ternary.
  return false unless node.consequent.is_a?(Else)

  truthy_body = node.statements.body
  falsy_body = node.consequent.statements.body

  (truthy_body.length == 1) && ternaryable?(truthy_body.first) &&
    (falsy_body.length == 1) && ternaryable?(falsy_body.first)
end