rails_upgrade/lib/gemfile_generator.rb

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module Rails
module Upgrading
class GemfileGenerator
def generate_new_gemfile
if has_environment?
generate_gemfile
else
raise FileNotFoundError, "Can't find environment.rb [config/environment.rb]!"
end
end
def has_environment?
File.exists?("config/environment.rb")
end
def environment_code
File.open("config/environment.rb").read
end
def generate_gemfile
environment_file = environment_code
# Get each line that starts with config.gem
gem_lines = environment_file.split("\n").select {|l| l =~ /^\s*config\.gem/}
# Toss those lines to a generator class; the lines are evaluated in the
# context of that instance.
config = GemfileGenerator.new
config.instance_eval(gem_lines.join("\n"))
config.output
end
end
class GemfileGenerator
# Creates a target for the config.gem calls
def config
self
end
def initialize
@gems = []
end
# Receive a call to add a gem to the list
def gem(name, options={})
data = {}
# Add new keys from old keys
data[:require] = options[:lib] if options[:lib]
data[:source] = options[:source] if options[:source]
version = options[:version]
@gems << [name, version, data]
end
# Generate the Gemfile output
def output
# Generic preamble, taken from Yehuda Katz's blog
preamble = <<STR
# Edit this Gemfile to bundle your application's dependencies.
# This preamble is the current preamble for Rails 3 apps; edit as needed.
source 'http://rubygems.org'
2011-04-07 22:05:17 +00:00
gem 'rails', '3.0.6'
STR
preamble + generate_upgraded_code
end
# Get Gemfile call for all the gems
def generate_upgraded_code
code = @gems.map do |name, version, data|
version_string = (version ? "'#{version}'" : nil)
source = data.delete(:source)
data_string = nil
unless data.empty?
data_string = data.to_a.map {|k, v| ":#{k} => '#{v}'"}.join(", ")
end
# If we have a source, generate a call to +source+ then output the
# gem call. Otherwise, just generate the gem requirement.
if source
str = ["'#{name}'", version_string, data_string].compact.join(", ")
"source '#{source}'\ngem #{str}"
else
str = ["'#{name}'", version_string, data_string].compact.join(", ")
"gem #{str}"
end
end.join("\n")
end
end
end
end