From 6e0a12c06ad3eb315a4f1599364b4ac3fa2384a0 Mon Sep 17 00:00:00 2001
From: Denis Defreyne <denis.defreyne@stoneship.org>
Date: Sat, 16 Apr 2016 21:27:32 +0200
Subject: [PATCH] Add Filter.define

---
 lib/nanoc/base/compilation/filter.rb |  7 +++++++
 spec/nanoc/base/filter_spec.rb       | 17 +++++++++++++++++
 2 files changed, 24 insertions(+)
 create mode 100644 spec/nanoc/base/filter_spec.rb

diff --git a/lib/nanoc/base/compilation/filter.rb b/lib/nanoc/base/compilation/filter.rb
index c42ef0d08a..cbbc9c17f9 100644
--- a/lib/nanoc/base/compilation/filter.rb
+++ b/lib/nanoc/base/compilation/filter.rb
@@ -38,6 +38,13 @@ class Filter < Nanoc::Int::Context
     extend Nanoc::Int::PluginRegistry::PluginMethods
 
     class << self
+      def define(ident)
+        filter_class = Class.new(::Nanoc::Filter) { identifier(ident) }
+        filter_class.send(:define_method, :run) do |content, params|
+          yield(content, params)
+        end
+      end
+
       # Sets the new type for the filter. The type can be `:binary` (default)
       # or `:text`. The given argument can either be a symbol indicating both
       # “from” and “to” types, or a hash where the only key is the “from” type
diff --git a/spec/nanoc/base/filter_spec.rb b/spec/nanoc/base/filter_spec.rb
new file mode 100644
index 0000000000..824c77b669
--- /dev/null
+++ b/spec/nanoc/base/filter_spec.rb
@@ -0,0 +1,17 @@
+describe Nanoc::Filter do
+  describe '.define' do
+    before do
+      Nanoc::Filter.define(:nanoc_filter_define_sample) do |content, params|
+        content.upcase
+      end
+    end
+
+    it 'defines a filter' do
+      expect(Nanoc::Filter.named(:nanoc_filter_define_sample)).not_to be_nil
+    end
+
+    it 'defines a callable filter' do
+      expect(Nanoc::Filter.named(:nanoc_filter_define_sample).new.run('foo', {})).to eql('FOO')
+    end
+  end
+end