Add inputs discovery.

Gemfile

@@ -1,6 +1,6 @@
 source "http://rubygems.org"
 
-gem "rails", "~> 3.0.0"
+gem "rails", "~> 3.0.7"
 
 group :test do
   gem "mocha",      :require => false

Gemfile.lock

@@ -35,7 +35,7 @@ GEM
       abstract (>= 1.0.0)
     i18n (0.5.0)
     linecache (0.43)
-    mail (2.2.17)
+    mail (2.2.18)
       activesupport (>= 2.3.6)
       i18n (>= 0.4.0)
       mime-types (~> 1.16)
@@ -71,12 +71,12 @@ GEM
     thor (0.14.6)
     treetop (1.4.9)
       polyglot (>= 0.3.1)
-    tzinfo (0.3.26)
+    tzinfo (0.3.27)
 
 PLATFORMS
   ruby
 
 DEPENDENCIES
   mocha
-  rails (~> 3.0.0)
+  rails (~> 3.0.7)
   ruby-debug

lib/simple_form.rb

@@ -128,6 +128,14 @@ module SimpleForm
   mattr_accessor :translate
   @@translate = true
 
+  # Automatically discover new inputs in Rails' autoload path.
+  mattr_accessor :inputs_discovery
+  @@inputs_discovery = true
+
+  # Cache simple form inputs discovery
+  mattr_accessor :cache_discovery
+  @@cache_discovery = !Rails.env.development?
+
   # Default way to setup SimpleForm. Run rails generate simple_form:install
   # to create a fresh initializer with all configuration values.
   def self.setup

lib/simple_form/form_builder.rb

@@ -13,6 +13,10 @@ module SimpleForm
     map_type :country, :time_zone,                            :to => SimpleForm::Inputs::PriorityInput
     map_type :boolean,                                        :to => SimpleForm::Inputs::BooleanInput
 
+    def self.discovery_cache
+      @discovery_cache ||= {}
+    end
+
     # Basic input helper, combines all components in the stack to generate
     # input html based on options the user define and some guesses through
     # database column information. By default a call to input will generate
@@ -85,8 +89,7 @@ module SimpleForm
       if block_given?
         SimpleForm::Inputs::BlockInput.new(self, attribute_name, column, input_type, options, &block).render
       else
-        klass = self.class.mappings[input_type] || self.class.const_get("#{input_type.to_s.camelize}Input")
-        klass.new(self, attribute_name, column, input_type, options).render
+        find_mapping(input_type).new(self, attribute_name, column, input_type, options).render
       end
     end
     alias :attribute :input
@@ -314,5 +317,51 @@ module SimpleForm
         @object.class.reflect_on_association(association)
       end
     end
+
+    # Attempts to find a mapping. It follows the following rules:
+    #
+    # 1) It tries to find a registered mapping, if succeeds:
+    #    a) If a mapping is found, try to find an alternative as #{mapping}Input
+    #    b) Or use the found mapping
+    # 2) If not, fallbacks to #{input_type}Input
+    # 3) If not, fallbacks to SimpleForm::Inputs::#{input_type}
+    def find_mapping(input_type) #:nodoc:
+      discovery_cache[input_type] ||=
+        if mapping = self.class.mappings[input_type]
+          mapping_override(mapping) || mapping
+        else
+          camelized = "#{input_type.to_s.camelize}Input"
+          attempt_mapping(camelized, Object) || attempt_mapping(camelized, self.class) ||
+            raise("No input found for #{input_type}")
+        end
+    end
+
+    # If cache_discovery is enabled, use the class level cache that persists
+    # between requests, otherwise use the instance one.
+    def discovery_cache #:nodoc:
+      if SimpleForm.cache_discovery
+        self.class.discovery_cache
+      else
+        @discovery_cache ||= {}
+      end
+    end
+
+    def mapping_override(klass) #:nodoc:
+      name = klass.name
+      if name =~ /^SimpleForm::Inputs/
+        attempt = "#{name.split("::").last}Input"
+        attempt_mapping attempt, Object
+      end
+    end
+
+    def attempt_mapping(mapping, at) #:nodoc:
+      return if SimpleForm.inputs_discovery == false && at == Object
+
+      begin
+        at.const_get(mapping)
+      rescue NameError => e
+        e.message =~ /#{mapping}$/ ? nil : raise
+      end
+    end
   end
 end

test/test_helper.rb

@@ -13,6 +13,12 @@ require 'action_view/template'
 require 'active_support/core_ext/module/deprecation'
 require 'action_view/test_case'
 
+module Rails
+  def self.env
+    ActiveSupport::StringInquirer.new("test")
+  end
+end
+
 $:.unshift File.expand_path("../../lib", __FILE__)
 require 'simple_form'