Code Nav PoC: Extend LSIF API with definition urls

This will allow us to implement Go-To-Definition feature

app/services/projects/lsif_data_service.rb

@@ -2,7 +2,8 @@
 
 module Projects
   class LsifDataService
-    attr_reader :file, :project, :path, :commit_id
+    attr_reader :file, :project, :path, :commit_id,
+      :docs, :doc_ranges, :ranges, :def_refs
 
     CACHE_EXPIRE_IN = 1.hour
 
@@ -14,19 +15,18 @@ module Projects
     end
 
     def execute
-      docs, doc_ranges, ranges =
-        fetch_data.values_at('docs', 'doc_ranges', 'ranges')
-
-      doc_id = doc_id_from(docs)
+      fetch_data!
 
       doc_ranges[doc_id]&.map do |range_id|
-        line_data, column_data = ranges[range_id]['loc']
+        location, ref_id = ranges[range_id].values_at('loc', 'ref_id')
+        line_data, column_data = location
 
         {
           start_line: line_data.first,
           end_line: line_data.last,
           start_char: column_data.first,
-          end_char: column_data.last
+          end_char: column_data.last,
+          definition_url: definition_url_for(def_refs[ref_id])
         }
       end
     end
@@ -47,8 +47,17 @@ module Projects
       end
     end
 
-    def doc_id_from(docs)
-      docs.reduce(nil) do |doc_id, (id, doc_path)|
+    def fetch_data!
+      data = fetch_data
+
+      @docs = data['docs']
+      @doc_ranges = data['doc_ranges']
+      @ranges = data['ranges']
+      @def_refs = data['def_refs']
+    end
+
+    def doc_id
+      @doc_id ||= docs.reduce(nil) do |doc_id, (id, doc_path)|
         next doc_id unless doc_path =~ /#{path}$/
 
         if doc_id.nil? || docs[doc_id].size > doc_path.size
@@ -58,5 +67,24 @@ module Projects
         doc_id
       end
     end
+
+    def dir_absolute_path
+      @dir_absolute_path ||= docs[doc_id]&.delete_suffix(path)
+    end
+
+    def definition_url_for(ref_id)
+      return unless range = ranges[ref_id]
+
+      def_doc_id, location = range.values_at('doc_id', 'loc')
+      localized_doc_url = docs[def_doc_id].delete_prefix(dir_absolute_path)
+
+      # location is stored as [[start_line, end_line], [start_char, end_char]]
+      start_line = location.first.first
+
+      line_anchor = "L#{start_line + 1}"
+      definition_ref_path = [commit_id, localized_doc_url].join('/')
+
+      Gitlab::Routing.url_helpers.project_blob_path(project, definition_ref_path, anchor: line_anchor)
+    end
   end
 end

spec/requests/api/lsif_data_spec.rb

@@ -60,7 +60,8 @@ describe API::LsifData do
             'end_char' => 18,
             'end_line' => 8,
             'start_char' => 13,
-            'start_line' => 8
+            'start_line' => 8,
+            'definition_url' => project_blob_path(project, "#{commit.id}/morestrings/reverse.go", anchor: 'L5')
           })
         end
 

spec/services/projects/lsif_data_service_spec.rb

@@ -23,43 +23,51 @@ describe Projects::LsifDataService do
     end
 
     context 'for main.go' do
+      let(:path_prefix) { "/#{project.full_path}/-/blob/#{commit_id}" }
+
       it 'returns lsif ranges for the file' do
         expect(service.execute).to eq([
           {
             end_char: 9,
             end_line: 6,
             start_char: 5,
-            start_line: 6
+            start_line: 6,
+            definition_url: "#{path_prefix}/main.go#L7"
           },
           {
             end_char: 36,
             end_line: 3,
             start_char: 1,
-            start_line: 3
+            start_line: 3,
+            definition_url: "#{path_prefix}/main.go#L4"
           },
           {
             end_char: 12,
             end_line: 7,
             start_char: 1,
-            start_line: 7
+            start_line: 7,
+            definition_url: "#{path_prefix}/main.go#L4"
           },
           {
             end_char: 20,
             end_line: 7,
             start_char: 13,
-            start_line: 7
+            start_line: 7,
+            definition_url: "#{path_prefix}/morestrings/reverse.go#L11"
           },
           {
             end_char: 12,
             end_line: 8,
             start_char: 1,
-            start_line: 8
+            start_line: 8,
+            definition_url: "#{path_prefix}/main.go#L4"
           },
           {
             end_char: 18,
             end_line: 8,
             start_char: 13,
-            start_line: 8
+            start_line: 8,
+            definition_url: "#{path_prefix}/morestrings/reverse.go#L5"
           }
         ])
       end
@@ -73,7 +81,8 @@ describe Projects::LsifDataService do
           end_char: 2,
           end_line: 11,
           start_char: 1,
-          start_line: 11
+          start_line: 11,
+          definition_url: "/#{project.full_path}/-/blob/#{commit_id}/morestrings/reverse.go#L12"
         })
       end
     end
@@ -87,7 +96,7 @@ describe Projects::LsifDataService do
     end
   end
 
-  describe '#doc_id_from' do
+  describe '#doc_id' do
     context 'when the passed path matches multiple files' do
       let(:path) { 'check/main.go' }
       let(:docs) do
@@ -100,7 +109,9 @@ describe Projects::LsifDataService do
       end
 
       it 'fetches the document with the shortest absolute path' do
-        expect(service.__send__(:doc_id_from, docs)).to eq(3)
+        service.instance_variable_set(:@docs, docs)
+
+        expect(service.__send__(:doc_id)).to eq(3)
       end
     end
   end