Question

Given a hash that contains function names like “find_by_user”, “find_by_id”, …

I want to search in a directory of files, and return a object that has each file name, along with the line numbers of where the function name occurred.

I have this so far:

files = Dir.glob(@folder_path)

files.each do |file_name|
  content = File.read(file_name)

end

This will be scanning a few hundred files.

Answer 1

Here’s the basic functionality you need:

# Given a path to a file and a regex,
# return an array of paired filename+line number matches
def matching_lines( file_path, regex )
  name = File.basename(file_path)
  File.readlines(file_path)
    .map.with_index{ |line,i| [name,line,i] }
    .select{ |name,line,i| line =~ regex }
    .map{ |name,line,i| [name,i] }
end

You can choose to use this as you like, iterating over multiple files and/or patterns, or using Regexp.union to create a pattern matching any one of a set of strings.

---

However: this is what grep was made for:

C:\>grep --line-number Nokogiri *.rb
push_nav_to_docs.rb:13: nav_dom = Nokogiri.XML(IO.read(NAV))
push_nav_to_docs.rb:39:         landing = Nokogiri.XML(html)
push_nav_to_docs.rb:53: doc = Nokogiri.XML(IO.read(doc_path))
push_nav_to_docs.rb:73: if File.exists?(toc_path) && toc = Nokogiri.XML(IO.read(toc_path)).at('ul')
push_nav_to_docs.rb:104:        container << Nokogiri.make("<ul/>").tap do |ul|

In Ruby you could call this code and get the output you want via:

lookfor = "Nokogiri"
grepped = `grep --line-number #{lookfor} *.rb`
results = grepped.scan(/^(.+?):(\d+)/)
#=> [["push_nav_to_docs.rb", "13"], ["push_nav_to_docs.rb", "39"], ["push_nav_to_docs.rb", "53"], ["push_nav_to_docs.rb", "73"], ["push_nav_to_docs.rb", "104"]]

Grep can also recurse into directories, match only particular file names, take regular expressions as patterns, and more.