Class: Hone::Patterns::HashMergeBang

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

Overview

Pattern: hash = hash.merge(other) -> hash.merge!(other)

Reassigning to the same variable after merge creates a new hash. merge! mutates in place, avoiding 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_local_variable_write_node(node) ⇒ Object 



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

def visit_local_variable_write_node(node)
  super

  # Look for: x = x.merge(...)
  value = node.value
  return unless value.is_a?(Prism::CallNode)
  return unless value.name == :merge

  receiver = value.receiver
  return unless receiver.is_a?(Prism::LocalVariableReadNode)
  return unless receiver.name == node.name

  add_finding(
    node,
    message: "Use `.merge!` instead of `#{node.name} = #{node.name}.merge(...)` to avoid creating new hash",
    speedup: "Avoids creating new hash, mutates in place"
  )
end