Class: Hone::Patterns::MapFlatten

Inherits:
Base
  • Object
show all
Defined in:
lib/hone/patterns/map_flatten.rb

Overview

Pattern: array.map { }.flatten -> array.flat_map { }

map.flatten creates an intermediate array from map, then flattens it. flat_map combines both operations avoiding the intermediate allocation.

Instance Attribute Summary

Attributes inherited from Base

#findings

Instance Method Summary collapse

Methods inherited from Base

#add_finding, inherited, #initialize, scan_file

Constructor Details

This class inherits a constructor from Hone::Patterns::Base

Instance Method Details

#visit_call_node(node) ⇒ Object 



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# File 'lib/hone/patterns/map_flatten.rb', line 13

def visit_call_node(node)
  super

  # Look for: .flatten where receiver is .map with a block
  return unless node.name == :flatten

  receiver = node.receiver
  return unless receiver.is_a?(Prism::CallNode)
  return unless receiver.name == :map && block_attached?(receiver)

  add_finding(
    node,
    message: "Use `.flat_map { }` instead of `.map { }.flatten` to avoid intermediate array",
    speedup: "Single pass, no intermediate allocation"
  )
end