1 files changed, 84 insertions, 0 deletions
diff --git a/runtime/lua/vim/lsp/buf.lua b/runtime/lua/vim/lsp/buf.lua
index 17cc698b76..fa0cbab138 100644
--- a/runtime/lua/vim/lsp/buf.lua
+++ b/runtime/lua/vim/lsp/buf.lua
@@ -495,6 +495,90 @@ function M.outgoing_calls()
   call_hierarchy(ms.callHierarchy_outgoingCalls)
 end
 
+--- @param method string
+local function type_hierarchy(method)
+  --- Merge results from multiple clients into a single table. Client-ID is preserved.
+  ---
+  --- @param results table<integer, {error: lsp.ResponseError, result: lsp.TypeHierarchyItem[]?}>
+  local function merge_results(results)
+    local merged_results = {}
+    for client_id, client_result in pairs(results) do
+      if client_result.error then
+        vim.notify(client_result.error.message, vim.log.levels.WARN)
+      elseif client_result.result then
+        for _, item in pairs(client_result.result) do
+          table.insert(merged_results, { client_id, item })
+        end
+      end
+    end
+    return merged_results
+  end
+
+  local bufnr = api.nvim_get_current_buf()
+  local params = util.make_position_params()
+  --- @param results table<integer, {error: lsp.ResponseError, result: lsp.TypeHierarchyItem[]?}>
+  vim.lsp.buf_request_all(bufnr, ms.textDocument_prepareTypeHierarchy, params, function(results)
+    local merged_results = merge_results(results)
+    if #merged_results == 0 then
+      vim.notify('No items resolved', vim.log.levels.INFO)
+      return
+    end
+
+    if #merged_results == 1 then
+      --- @type {integer, lsp.TypeHierarchyItem}
+      local item = merged_results[1]
+      local client = vim.lsp.get_client_by_id(item[1])
+      if client then
+        --- @type lsp.TypeHierarchyItem
+        client.request(method, { item = item[2] }, nil, bufnr)
+      else
+        vim.notify(
+          string.format('Client with id=%d disappeared during call hierarchy request', item[1]),
+          vim.log.levels.WARN
+        )
+      end
+    else
+      local opts = {
+        prompt = 'Select a type hierarchy item:',
+        kind = 'typehierarchy',
+        format_item = function(item)
+          if not item[2].detail or #item[2].detail == 0 then
+            return item[2].name
+          end
+          return string.format('%s %s', item[2].name, item[2].detail)
+        end,
+      }
+
+      vim.ui.select(merged_results, opts, function(item)
+        local client = vim.lsp.get_client_by_id(item[1])
+        if client then
+          --- @type lsp.TypeHierarchyItem
+          client.request(method, { item = item[2] }, nil, bufnr)
+        else
+          vim.notify(
+            string.format('Client with id=%d disappeared during call hierarchy request', item[1]),
+            vim.log.levels.WARN
+          )
+        end
+      end)
+    end
+  end)
+end
+
+--- Lists all the subtypes of the symbol under the
+--- cursor in the |quickfix| window. If the symbol can resolve to
+--- multiple items, the user can pick one using |vim.ui.select()|.
+function M.subtypes()
+  type_hierarchy(ms.typeHierarchy_subtypes)
+end
+
+--- Lists all the supertypes of the symbol under the
+--- cursor in the |quickfix| window. If the symbol can resolve to
+--- multiple items, the user can pick one using |vim.ui.select()|.
+function M.supertypes()
+  type_hierarchy(ms.typeHierarchy_supertypes)
+end
+
 --- List workspace folders.
 ---
 function M.list_workspace_folders()