CODEWITHSUNDEEP
ruby
mareiou
mareiou

Reputation: 414

Ruby how to unroll a hash table and concatenate its values

I have the following table in a yaml format:

:first_directory:
 :component1:
  - component1.c
  - component1.h
 :component2:
  :component2_A:
   :src:
    - component2_A.c
   :inc:
    - component2_A.h

When I print the content of the hash I get:

{:first_directory=>{:component1=>["component1.c", "component1.h"], :component2=>{:component2_A=>{:src=>["component2_A.c"], :inc=>["component2_A.h"]}}}}

Now I want to be able to create strings to concatenate all the possible values of a hash hierarchy and split it using a character. What I would like to generate are strings that look like this:

first_directory/component1/component1.c
first_directory/component1/component1.h
first_directory/component2/component2_A/src/component2_A.c
first_directory/component2/component2_A/inc/component2_A.h

What would be the cleanest and best way to achieve this?

Upvotes: 3

Views: 146

Answers (2)

Ivan Olshansky
Ivan Olshansky

Reputation: 969

This method should work best way:

def print_hash(hash_node, prev_string=nil)
  if hash_node.class == Array
    hash_node.each {|element| puts "#{prev_string}#{element}"}
  else # it is an inner hash
    hash_node.each do |key, value|
      print_hash(value, "#{prev_string}#{key}/")
    end
  end
end

print_hash(content_as_a_hash)

Test run:

content_as_a_hash = {:first_directory=>{:component1=>["component1.c", "component1.h"], :component2=>{:component2_A=>{:src=>["component2_A.c"], :inc=>["component2_A.h"]}}}}

print_hash(content_as_a_hash)

Results:

first_directory/component1/component1.c
first_directory/component1/component1.h
first_directory/component2/component2_A/src/component2_A.c
first_directory/component2/component2_A/inc/component2_A.h

Upvotes: 5

Cary Swoveland
Cary Swoveland

Reputation: 110755

As the YAML string uses indentation to indicate structure, you could obtain the desired result by operating on the string directly, employing a stack.

arr=<<_.lines
:first_directory:
 :component1:
  - component1.c
  - component1.h
 :component2:
  :component2_A:
   :src:
    - component2_A.c
   :inc:
    - component2_A.h
_
  #=> [":first_directory:\n",
  #    " :component1:\n",
  #    "  - component1.c\n",
  #    "  - component1.h\n",
  #    " :component2:\n",
  #    "  :component2_A:\n",
  #    "   :src:\n",
  #    "    - component2_A.c\n",
  #    "   :inc:\n",
  #    "    - component2_A.h\n"] 


def rollup(stack)
  stack.transpose.last.join('/')
end

stack = []

arr.each_with_object([]) do |line,arr|
  indent = line =~ /\S/
  line.gsub!(/[:\s-]/, '')
  if stack.any? && indent <= stack.last.first
    arr << rollup(stack)
    stack.select! { |ind,_| ind < indent }
  end
  stack << [indent, line]
end << rollup(stack)
  #=> ["first_directory/component1/component1.c", 
  #    "first_directory/component1/component1.h", 
  #    "first_directory/component2/component2_A/src/component2_A.c", 
  #    "first_directory/component2/component2_A/inc/component2_A.h"]

Upvotes: 3

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