1 files changed, 123 insertions, 0 deletions
diff --git a/railties/lib/rails/command/behavior.rb b/railties/lib/rails/command/behavior.rb
new file mode 100644
index 0000000000..4a92f72f16
--- /dev/null
+++ b/railties/lib/rails/command/behavior.rb
@@ -0,0 +1,123 @@
+require "active_support"
+
+module Rails
+  module Command
+    module Behavior #:nodoc:
+      extend ActiveSupport::Concern
+
+      class_methods do
+        # Remove the color from output.
+        def no_color!
+          Thor::Base.shell = Thor::Shell::Basic
+        end
+
+        # Track all command subclasses.
+        def subclasses
+          @subclasses ||= []
+        end
+
+        private
+
+          # This code is based directly on the Text gem implementation.
+          # Copyright (c) 2006-2013 Paul Battley, Michael Neumann, Tim Fletcher.
+          #
+          # Returns a value representing the "cost" of transforming str1 into str2.
+          def levenshtein_distance(str1, str2) # :doc:
+            s = str1
+            t = str2
+            n = s.length
+            m = t.length
+
+            return m if (0 == n)
+            return n if (0 == m)
+
+            d = (0..m).to_a
+            x = nil
+
+            # avoid duplicating an enumerable object in the loop
+            str2_codepoint_enumerable = str2.each_codepoint
+
+            str1.each_codepoint.with_index do |char1, i|
+              e = i + 1
+
+              str2_codepoint_enumerable.with_index do |char2, j|
+                cost = (char1 == char2) ? 0 : 1
+                x = [
+                     d[j + 1] + 1, # insertion
+                     e + 1,      # deletion
+                     d[j] + cost # substitution
+                    ].min
+                d[j] = e
+                e = x
+              end
+
+              d[m] = x
+            end
+
+            x
+          end
+
+          # Prints a list of generators.
+          def print_list(base, namespaces)
+            return if namespaces.empty?
+            puts "#{base.camelize}:"
+
+            namespaces.each do |namespace|
+              puts("  #{namespace}")
+            end
+
+            puts
+          end
+
+          # Receives namespaces in an array and tries to find matching generators
+          # in the load path.
+          def lookup(namespaces)
+            paths = namespaces_to_paths(namespaces)
+
+            paths.each do |raw_path|
+              lookup_paths.each do |base|
+                path = "#{base}/#{raw_path}_#{command_type}"
+
+                begin
+                  require path
+                  return
+                rescue LoadError => e
+                  raise unless e.message =~ /#{Regexp.escape(path)}$/
+                rescue Exception => e
+                  warn "[WARNING] Could not load #{command_type} #{path.inspect}. Error: #{e.message}.\n#{e.backtrace.join("\n")}"
+                end
+              end
+            end
+          end
+
+          # This will try to load any command in the load path to show in help.
+          def lookup!
+            $LOAD_PATH.each do |base|
+              Dir[File.join(base, *file_lookup_paths)].each do |path|
+                begin
+                  path = path.sub("#{base}/", "")
+                  require path
+                rescue Exception
+                  # No problem
+                end
+              end
+            end
+          end
+
+          # Convert namespaces to paths by replacing ":" for "/" and adding
+          # an extra lookup. For example, "rails:model" should be searched
+          # in both: "rails/model/model_generator" and "rails/model_generator".
+          def namespaces_to_paths(namespaces)
+            paths = []
+            namespaces.each do |namespace|
+              pieces = namespace.split(":")
+              paths << pieces.dup.push(pieces.last).join("/")
+              paths << pieces.join("/")
+            end
+            paths.uniq!
+            paths
+          end
+      end
+    end
+  end
+end