Remove duplication in reference filters

lib/gitlab/markdown/abstract_reference_filter.rb

+require 'gitlab/markdown'
+
+module Gitlab
+  module Markdown
+    # Issues, Snippets and Merge Requests shares similar functionality in refernce filtering.
+    # All this functionality moved to this class
+    class AbstractReferenceFilter < ReferenceFilter
+      include CrossProjectReference
+
+      def self.object_class
+        # Implement in child class
+        # Example: MergeRequest
+      end
+
+      def self.object_name
+        object_class.name.underscore
+      end
+
+      def self.object_sym
+        object_name.to_sym
+      end
+
+      def self.data_reference
+        "data-#{object_name.dasherize}"
+      end
+
+      # Public: Find references in text (like `!123` for merge requests)
+      #
+      #   AnyReferenceFilter.references_in(text) do |match, object|
+      #     "<a href=...>PREFIX#{object}</a>"
+      #   end
+      #
+      # PREFIX - symbol that detects reference (like ! for merge requests)
+      # object - reference object (snippet, merget request etc)
+      # text - String text to search.
+      #
+      # Yields the String match, the Integer referenced object ID, and an optional String
+      # of the external project reference.
+      #
+      # Returns a String replaced with the return of the block.
+      def self.references_in(text)
+        text.gsub(object_class.reference_pattern) do |match|
+          yield match, $~[object_sym].to_i, $~[:project]
+        end
+      end
+
+      def self.referenced_by(node)
+        { object_sym => LazyReference.new(object_class, node.attr(data_reference)) }
+      end
+
+      delegate :object_class, :object_sym, :references_in, to: :class
+
+      def find_object(project, id)
+        # Implement in child class
+        # Example: project.merge_requests.find
+      end
+
+      def url_for_object(object, project)
+        # Implement in child class
+        # Example: project_merge_request_url
+      end
+
+      def call
+        replace_text_nodes_matching(object_class.reference_pattern) do |content|
+          object_link_filter(content)
+        end
+      end
+
+      # Replace references (like `!123` for merge requests) in text with links
+      # to the referenced object's details page.
+      #
+      # text - String text to replace references in.
+      #
+      # Returns a String with references replaced with links. All links
+      # have `gfm` and `gfm-OBJECT_NAME` class names attached for styling.
+      def object_link_filter(text)
+        references_in(text) do |match, id, project_ref|
+          project = project_from_ref(project_ref)
+
+          if project && object = find_object(project, id)
+            title = escape_once("#{object_title}: #{object.title}")
+            klass = reference_class(object_sym)
+            data  = data_attribute(project: project.id, object_sym => object.id)
+            url = url_for_object(object, project)
+
+            %(<a href="#{url}" #{data}
+                 title="#{title}"
+                 class="#{klass}">#{match}</a>)
+          else
+            match
+          end
+        end
+      end
+
+      def object_title
+        object_class.name.titleize
+      end
+    end
+  end
+end

lib/gitlab/markdown/issue_reference_filter.rb

@@ -6,66 +6,17 @@ module Gitlab
     # issues that do not exist are ignored.
     #
     # This filter supports cross-project references.
-    class IssueReferenceFilter < ReferenceFilter
-      include CrossProjectReference
-
-      # Public: Find `#123` issue references in text
-      #
-      #   IssueReferenceFilter.references_in(text) do |match, issue, project_ref|
-      #     "<a href=...>##{issue}</a>"
-      #   end
-      #
-      # text - String text to search.
-      #
-      # Yields the String match, the Integer issue ID, and an optional String of
-      # the external project reference.
-      #
-      # Returns a String replaced with the return of the block.
-      def self.references_in(text)
-        text.gsub(Issue.reference_pattern) do |match|
-          yield match, $~[:issue].to_i, $~[:project]
-        end
-      end
-
-      def self.referenced_by(node)
-        { issue: LazyReference.new(Issue, node.attr("data-issue")) }
-      end
-
-      def call
-        replace_text_nodes_matching(Issue.reference_pattern) do |content|
-          issue_link_filter(content)
-        end
+    class IssueReferenceFilter < AbstractReferenceFilter
+      def self.object_class
+        Issue
       end
 
-      # Replace `#123` issue references in text with links to the referenced
-      # issue's details page.
-      #
-      # text - String text to replace references in.
-      #
-      # Returns a String with `#123` references replaced with links. All links
-      # have `gfm` and `gfm-issue` class names attached for styling.
-      def issue_link_filter(text)
-        self.class.references_in(text) do |match, id, project_ref|
-          project = self.project_from_ref(project_ref)
-
-          if project && issue = project.get_issue(id)
-            url = url_for_issue(id, project, only_path: context[:only_path])
-
-            title = escape_once("Issue: #{issue.title}")
-            klass = reference_class(:issue)
-            data  = data_attribute(project: project.id, issue: issue.id)
-
-            %(<a href="#{url}" #{data}
-                 title="#{title}"
-                 class="#{klass}">#{match}</a>)
-          else
-            match
-          end
-        end
+      def find_object(project, id)
+        project.get_issue(id)
       end
 
-      def url_for_issue(*args)
-        IssuesHelper.url_for_issue(*args)
+      def url_for_object(issue, project)
+        IssuesHelper.url_for_issue(issue.iid, project, only_path: context[:only_path])
       end
     end
   end

lib/gitlab/markdown/merge_request_reference_filter.rb

@@ -6,65 +6,16 @@ module Gitlab
     # to merge requests that do not exist are ignored.
     #
     # This filter supports cross-project references.
-    class MergeRequestReferenceFilter < ReferenceFilter
-      include CrossProjectReference
-
-      # Public: Find `!123` merge request references in text
-      #
-      #   MergeRequestReferenceFilter.references_in(text) do |match, merge_request, project_ref|
-      #     "<a href=...>##{merge_request}</a>"
-      #   end
-      #
-      # text - String text to search.
-      #
-      # Yields the String match, the Integer merge request ID, and an optional
-      # String of the external project reference.
-      #
-      # Returns a String replaced with the return of the block.
-      def self.references_in(text)
-        text.gsub(MergeRequest.reference_pattern) do |match|
-          yield match, $~[:merge_request].to_i, $~[:project]
-        end
-      end
-
-      def self.referenced_by(node)
-        { merge_request: LazyReference.new(MergeRequest, node.attr("data-merge-request")) }
-      end
-
-      def call
-        replace_text_nodes_matching(MergeRequest.reference_pattern) do |content|
-          merge_request_link_filter(content)
-        end
+    class MergeRequestReferenceFilter < AbstractReferenceFilter
+      def self.object_class
+        MergeRequest
       end
 
-      # Replace `!123` merge request references in text with links to the
-      # referenced merge request's details page.
-      #
-      # text - String text to replace references in.
-      #
-      # Returns a String with `!123` references replaced with links. All links
-      # have `gfm` and `gfm-merge_request` class names attached for styling.
-      def merge_request_link_filter(text)
-        self.class.references_in(text) do |match, id, project_ref|
-          project = self.project_from_ref(project_ref)
-
-          if project && merge_request = project.merge_requests.find_by(iid: id)
-            title = escape_once("Merge Request: #{merge_request.title}")
-            klass = reference_class(:merge_request)
-            data  = data_attribute(project: project.id, merge_request: merge_request.id)
-
-            url = url_for_merge_request(merge_request, project)
-
-            %(<a href="#{url}" #{data}
-                 title="#{title}"
-                 class="#{klass}">#{match}</a>)
-          else
-            match
-          end
-        end
+      def find_object(project, id)
+        project.merge_requests.find_by(iid: id)
       end
 
-      def url_for_merge_request(mr, project)
+      def url_for_object(mr, project)
         h = Gitlab::Application.routes.url_helpers
         h.namespace_project_merge_request_url(project.namespace, project, mr,
                                             only_path: context[:only_path])

lib/gitlab/markdown/snippet_reference_filter.rb

@@ -6,65 +6,16 @@ module Gitlab
     # snippets that do not exist are ignored.
     #
     # This filter supports cross-project references.
-    class SnippetReferenceFilter < ReferenceFilter
-      include CrossProjectReference
-
-      # Public: Find `$123` snippet references in text
-      #
-      #   SnippetReferenceFilter.references_in(text) do |match, snippet|
-      #     "<a href=...>$#{snippet}</a>"
-      #   end
-      #
-      # text - String text to search.
-      #
-      # Yields the String match, the Integer snippet ID, and an optional String
-      # of the external project reference.
-      #
-      # Returns a String replaced with the return of the block.
-      def self.references_in(text)
-        text.gsub(Snippet.reference_pattern) do |match|
-          yield match, $~[:snippet].to_i, $~[:project]
-        end
-      end
-
-      def self.referenced_by(node)
-        { snippet: LazyReference.new(Snippet, node.attr("data-snippet")) }
-      end
-
-      def call
-        replace_text_nodes_matching(Snippet.reference_pattern) do |content|
-          snippet_link_filter(content)
-        end
+    class SnippetReferenceFilter < AbstractReferenceFilter
+      def self.object_class
+        Snippet
       end
 
-      # Replace `$123` snippet references in text with links to the referenced
-      # snippets's details page.
-      #
-      # text - String text to replace references in.
-      #
-      # Returns a String with `$123` references replaced with links. All links
-      # have `gfm` and `gfm-snippet` class names attached for styling.
-      def snippet_link_filter(text)
-        self.class.references_in(text) do |match, id, project_ref|
-          project = self.project_from_ref(project_ref)
-
-          if project && snippet = project.snippets.find_by(id: id)
-            title = escape_once("Snippet: #{snippet.title}")
-            klass = reference_class(:snippet)
-            data  = data_attribute(project: project.id, snippet: snippet.id)
-
-            url = url_for_snippet(snippet, project)
-
-            %(<a href="#{url}" #{data}
-                 title="#{title}"
-                 class="#{klass}">#{match}</a>)
-          else
-            match
-          end
-        end
+      def find_object(project, id)
+        project.snippets.find_by(id: id)
       end
 
-      def url_for_snippet(snippet, project)
+      def url_for_object(snippet, project)
         h = Gitlab::Application.routes.url_helpers
         h.namespace_project_snippet_url(project.namespace, project, snippet,
                                         only_path: context[:only_path])