/lib/expand_variables.rb

 1module ExpandVariables
 2  class << self
 3    def expand(value, variables)
 4      # Convert hash array to variables
 5      if variables.is_a?(Array)
 6        variables = variables.reduce({}) do |hash, variable|
 7          hash[variable[:key]] = variable[:value]
 8          hash
 9        end
10      end
11
12      value.gsub(/\$([a-zA-Z_][a-zA-Z0-9_]*)|\${\g<1>}|%\g<1>%/) do
13        variables[$1 || $2]
14      end
15    end
16  end
17end