Class: Preval::Visitors::Fasterer

Inherits:
Preval::Visitor show all
Defined in:
lib/preval/visitors/fasterer.rb

Overview

All of these optimizations come from the ‘fasterer` gem.

Instance Method Summary collapse

Methods inherited from Preval::Visitor

enable!

Instance Method Details

#on_call(node) ⇒ Object 



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# File 'lib/preval/visitors/fasterer.rb', line 7

def on_call(node)
  left, _period, right = node.body

  # replace `.reverse.each` with `.reverse_each`
  # replace `.shuffle.first` with `.sample`
  # replace `.sort.first` with `min`
  # replace `.sort.last` with `max`
  if node.type_match?(:call, :@period, :@ident) &&
     # foo.each
     left.type_match?(%i[array vcall], :@period, :@ident)
     # foo.reverse

    callleft, callperiod, callright = left.body

    if callright.body == 'reverse' && right.body == 'each'
      callright.update(:@ident, 'reverse_each')
      node.update(:call, [callleft, callperiod, callright])
    elsif callright.body == 'sort' && right.body == 'first'
      callright.update(:@ident, 'min')
      node.update(:call, [callleft, callperiod, callright])
    elsif callright.body == 'sort' && right.body == 'last'
      callright.update(:@ident, 'max')
      node.update(:call, [callleft, callperiod, callright])
    elsif callright.body == 'shuffle' && right.body == 'first'
      callright.update(:@ident, 'sample')
      node.update(:call, [callleft, callperiod, callright])
    end
  end
end

#on_method_add_arg(node) ⇒ Object 



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# File 'lib/preval/visitors/fasterer.rb', line 37

def on_method_add_arg(node)
  # replace `.gsub('...', '...')` with `.tr('...', '...')`
  if node.type_match?(:call, :arg_paren) &&
     # foo.gsub()
     node[0].type_match?(:vcall, :@period, :@ident) &&
     # foo.gsub
     node[0, 2].body == 'gsub'
     # the method being called is gsub

    left = node[1, 0, 0, 0, 1]
    right = node[1, 0, 0, 1]

    if left.is?(:string_literal) &&
       right.is?(:string_literal) &&
       [left, right].all? do |string|
         string[0, 1].is?(:@tstring_content) &&
         string[0, 1].body.length == 1
       end

      node[0, 2].update(:@ident, 'tr')
    end
  end

  # replace `.map { ... }.flatten(1)` with `.flat_map { ... }`
  if node.type_match?(:call, :arg_paren) &&
     # foo.flatten()
     node[0].type_match?(:method_add_block, :@period, :@ident) &&
     # foo.map {}
     node[0, 0, 0].type_match?(%i[array vcall], :@period, :@ident) &&
     # foo.flatten
     node[0, 0, 0, 2].body == 'map' &&
     # the inner call is a call to map
     node[0, 2].body == 'flatten' &&
     # the outer call is a call to flatten
     node[1].is?(:arg_paren) &&
     # flatten has a param
     node[1, 0, 0].type_match?(:args_new, :@int) &&
     # there is only one argument to flatten and it is an integer
     node[1, 0, 0, 1].body == '1'
     # the value of the argument to flatten is 1

    node[0, 0, 0, 2].update(:@ident, 'flat_map')
    node.update(:method_add_block, node[0, 0].body)
  end
end