1 files changed, 48 insertions, 0 deletions
diff --git a/lib/nickserver/handler_chain.rb b/lib/nickserver/handler_chain.rb
new file mode 100644
index 0000000..afc24a5
--- /dev/null
+++ b/lib/nickserver/handler_chain.rb
@@ -0,0 +1,48 @@
+#
+# Handler Chain
+#
+# A chain of handlers that respond to call. Invoking handle(*args) on the chain
+# will call the handlers with the given args until one of them returns a result
+# that is truethy (i.e. not false or nil).
+#
+# You can specify exception classes to rescue with
+#   handler_chain.continue_on ErrorClass1, ErrorClass2
+# These exceptions will be rescued and tracked. The chain will proceed even if
+# one handler raised the given exception. Afterwards you can inspect them with
+#   handler_chain.rescued_exceptions
+#
+
+module Nickserver
+  class HandlerChain
+
+    def initialize(*handlers)
+      @handlers = handlers
+      @exceptions_to_rescue = []
+      @rescued_exceptions = []
+    end
+
+    def continue_on(*exceptions)
+      self.exceptions_to_rescue += exceptions
+    end
+
+    def handle(*args)
+      result = nil
+      _handled_by = @handlers.find{|h| result = try_handler(h, *args)}
+      result
+    end
+
+    attr_reader :rescued_exceptions
+
+    protected
+
+    attr_writer :rescued_exceptions
+    attr_accessor :exceptions_to_rescue
+
+    def try_handler(handler, *args)
+      result = handler.call(*args)
+    rescue *exceptions_to_rescue
+      self.rescued_exceptions << $!
+      result = false
+    end
+  end
+end