Ruby find all Constants

Question

I am new to Ruby so sorry if it's a simple question. I want to open a ruby file and search all constants, but I don't know the right regular expression.

Here is my simplified code:

def findconst()
 filename = @path_main  
 k= {}
 akonstanten = []
 k[:konstanten] = akonstanten


 if (File.exists?(filename))
  file = open(filename, "r")
   while (line = file.gets)
    if (line =~  ????)
     k[:konstanten] << line
    end
   end
 end 
end

To do it reliably you need to parse the code into AST, and this is not something you can do with regexes. — Sergio Tulentsev
– Sergio Tulentsev, Commented Dec 5, 2012 at 10:43
does your file simply contain a known set of classes/modules ? — tomferon
– tomferon, Commented Dec 5, 2012 at 10:49
i want to parse several files, just to know which constants, functions ect they contain. — user1878703
– user1878703, Commented Dec 5, 2012 at 10:52
@user1878703: you get all words that are in caps, but what about this one MAGIC_STRING = "This is a word in CAPS"? How many constants do you see here? — Sergio Tulentsev
– Sergio Tulentsev, Commented Dec 5, 2012 at 10:55

user1790619 · Accepted Answer · 2012-12-05 12:27:40Z

2

You can use Ripper library to extract the tokens.

For example, this code will return you constants and methods names for the file

A = "String" # Comment
B = <<-STR
  Yet Another String
STR

class C
  class D
    def method_1
    end
    def method_2
    end
  end
end

require "ripper"

tokens = Ripper.lex(File.read("file.rb"))

pp tokens.group_by { |x| x[1] }[:on_ident].map(&:last)
pp tokens.group_by { |x| x[1] }[:on_const].map(&:last)

# => ["method_1", "method_2"]
# => ["A", "B", "C", "D"]

answered Dec 5, 2012 at 12:27

user1790619

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Comments

meesern · Accepted Answer · 2012-12-05 11:51:46Z

0

As Sergio Says searching for words with Caps won't just give you constants but if it's good enough it's good enough.

The regexpression you are looking for is something like

if (line =~ /[^a-z][A-Z]/)

Which says match any capital that is not preceded by a lower case letter. Of course this will only count one per line so you might like to consider tokenising the stream and working on tokens, not lines.

answered Dec 5, 2012 at 11:51

meesern

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3 Comments

user1878703 Over a year ago

this isnt working for me it still find words like Controller, i have to use ruby 1.8.7 if its important.

Jörg W Mittag Over a year ago

Controller is a constant (assuming that it is a variable identifier, of course), since it starts with a capital letter.

user1878703 Over a year ago

the word was maybe not the best example but it outputs me all words which start with a capital, i want only words like THIS or EXAMPLE

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