1 files changed, 47 insertions, 5 deletions

diff --git a/lib/gitlab/slash_commands/dsl.rb b/lib/gitlab/slash_commands/dsl.rb
index 50b0937d267..614bafbe1b2 100644
--- a/lib/gitlab/slash_commands/dsl.rb
+++ b/lib/gitlab/slash_commands/dsl.rb
@@ -44,6 +44,22 @@ module Gitlab
           @params = params
         end
 
+        # Allows to give an explanation of what the command will do when
+        # executed. This explanation is shown when rendering the Markdown
+        # preview.
+        #
+        # Example:
+        #
+        #   explanation do |arguments|
+        #     "Adds label(s) #{arguments.join(' ')}"
+        #   end
+        #   command :command_key do |arguments|
+        #     # Awesome code block
+        #   end
+        def explanation(text = '', &block)
+          @explanation = block_given? ? block : text
+        end
+
         # Allows to define conditions that must be met in order for the command
         # to be returned by `.command_names` & `.command_definitions`.
         # It accepts a block that will be evaluated with the context given to
@@ -61,6 +77,24 @@ module Gitlab
           @condition_block = block
         end
 
+        # Allows to perform initial parsing of parameters. The result is passed
+        # both to `command` and `explanation` blocks, instead of the raw
+        # parameters.
+        # It accepts a block that will be evaluated with the context given to
+        # `CommandDefintion#to_h`.
+        #
+        # Example:
+        #
+        #   parse_params do |raw|
+        #     raw.strip
+        #   end
+        #   command :command_key do |parsed|
+        #     # Awesome code block
+        #   end
+        def parse_params(&block)
+          @parse_params_block = block
+        end
+
         # Registers a new command which is recognizeable from body of email or
         # comment.
         # It accepts aliases and takes a block.
@@ -75,11 +109,13 @@ module Gitlab
 
           definition = CommandDefinition.new(
             name,
-            aliases:          aliases,
-            description:      @description,
-            params:           @params,
-            condition_block:  @condition_block,
-            action_block:     block
+            aliases: aliases,
+            description: @description,
+            explanation: @explanation,
+            params: @params,
+            condition_block: @condition_block,
+            parse_params_block: @parse_params_block,
+            action_block: block
           )
 
           self.command_definitions << definition
@@ -89,8 +125,14 @@ module Gitlab
           end
 
           @description = nil
+          @explanation = nil
           @params = nil
           @condition_block = nil
+          @parse_params_block = nil
+        end
+
+        def definition_by_name(name)
+          command_definitions_by_name[name.to_sym]
         end
       end
     end