4 files changed, 87 insertions, 1 deletions

diff --git a/runtime/lua/vim/lsp.lua b/runtime/lua/vim/lsp.lua
index dacdbcfa17..92f56b2ddf 100644
--- a/runtime/lua/vim/lsp.lua
+++ b/runtime/lua/vim/lsp.lua
@@ -597,7 +597,10 @@ function lsp.start_client(config)
       --  -- workspace folder in the user interface.
       --  name
       -- }
-      workspaceFolders = nil;
+      workspaceFolders = {{
+        uri = vim.uri_from_fname(config.root_dir);
+        name = string.format("%s", config.root_dir);
+      }};
     }
     if config.before_init then
       -- TODO(ashkan) handle errors here.
@@ -610,6 +613,7 @@ function lsp.start_client(config)
       rpc.notify('initialized', {[vim.type_idx]=vim.types.dictionary})
       client.initialized = true
       uninitialized_clients[client_id] = nil
+      client.workspaceFolders = initialize_params.workspaceFolders
       client.server_capabilities = assert(result.capabilities, "initialize result doesn't contain capabilities")
       -- These are the cleaned up capabilities we use for dynamically deciding
       -- when to send certain events to clients.
diff --git a/runtime/lua/vim/lsp/buf.lua b/runtime/lua/vim/lsp/buf.lua
index fa62905c0a..a70581478b 100644
--- a/runtime/lua/vim/lsp/buf.lua
+++ b/runtime/lua/vim/lsp/buf.lua
@@ -238,6 +238,61 @@ function M.outgoing_calls()
   end)
 end
 
+--- List workspace folders.
+function M.list_workspace_folders()
+  local workspace_folders = {}
+  for _, client in ipairs(vim.lsp.buf_get_clients()) do
+    for _, folder in ipairs(client.workspaceFolders) do
+      table.insert(workspace_folders, folder.name)
+    end
+  end
+  return workspace_folders
+end
+
+--- Add a workspace folder.
+function M.add_workspace_folder(workspace_folder)
+  workspace_folder = workspace_folder or npcall(vfn.input, "Workspace Folder: ", vfn.expand('%:p:h'))
+  vim.api.nvim_command("redraw")
+  if not (workspace_folder and #workspace_folder > 0) then return end
+  if vim.fn.isdirectory(workspace_folder) == 0 then
+    print(workspace_folder, " is not a valid directory")
+    return
+  end
+  local params = util.make_workspace_params({{uri = vim.uri_from_fname(workspace_folder); name = workspace_folder}}, {{}})
+  for _, client in ipairs(vim.lsp.buf_get_clients()) do
+    local found = false
+    for _, folder in ipairs(client.workspaceFolders) do
+      if folder.name == workspace_folder then
+        found = true
+        print(workspace_folder, "is already part of this workspace")
+        break
+      end
+    end
+    if not found then
+      vim.lsp.buf_notify(0, 'workspace/didChangeWorkspaceFolders', params)
+      table.insert(client.workspaceFolders, params.event.added[1])
+    end
+  end
+end
+
+--- Remove a workspace folder.
+function M.remove_workspace_folder(workspace_folder)
+  workspace_folder = workspace_folder or npcall(vfn.input, "Workspace Folder: ", vfn.expand('%:p:h'))
+  vim.api.nvim_command("redraw")
+  if not (workspace_folder and #workspace_folder > 0) then return end
+  local params = util.make_workspace_params({{}}, {{uri = vim.uri_from_fname(workspace_folder); name = workspace_folder}})
+  for _, client in ipairs(vim.lsp.buf_get_clients()) do
+    for idx, folder in ipairs(client.workspaceFolders) do
+      if folder.name == workspace_folder then
+        vim.lsp.buf_notify(0, 'workspace/didChangeWorkspaceFolders', params)
+        client.workspaceFolders[idx] = nil
+        return
+      end
+    end
+  end
+  print(workspace_folder,  "is not currently part of the workspace")
+end
+
 --- Lists all symbols in the current workspace in the quickfix window.
 ---
 --- The list is filtered against {query}; if the argument is omitted from the
diff --git a/runtime/lua/vim/lsp/protocol.lua b/runtime/lua/vim/lsp/protocol.lua
index 07b4e8b926..1f21bd7eb0 100644
--- a/runtime/lua/vim/lsp/protocol.lua
+++ b/runtime/lua/vim/lsp/protocol.lua
@@ -716,6 +716,7 @@ function protocol.make_client_capabilities()
         };
         hierarchicalWorkspaceSymbolSupport = true;
       };
+      workspaceFolders = true;
       applyEdit = true;
     };
     callHierarchy = {
@@ -974,6 +975,28 @@ function protocol.resolve_capabilities(server_capabilities)
     error("The server sent invalid implementationProvider")
   end
 
+  local workspace = server_capabilities.workspace
+  local workspace_properties = {}
+  if workspace == nil or workspace.workspaceFolders == nil then
+    -- Defaults if omitted.
+    workspace_properties = {
+      workspace_folder_properties =  {
+        supported = false;
+        changeNotifications=false;
+      }
+    }
+  elseif type(workspace.workspaceFolders) == 'table' then
+    workspace_properties = {
+      workspace_folder_properties = {
+        supported = vim.F.ifnil(workspace.workspaceFolders.supported, false);
+        changeNotifications = vim.F.ifnil(workspace.workspaceFolders.changeNotifications, false);
+
+      }
+    }
+  else
+    error("The server sent invalid workspace")
+  end
+
   local signature_help_properties
   if server_capabilities.signatureHelpProvider == nil then
     signature_help_properties = {
@@ -993,6 +1016,7 @@ function protocol.resolve_capabilities(server_capabilities)
   return vim.tbl_extend("error"
       , text_document_sync_properties
       , signature_help_properties
+      , workspace_properties
       , general_properties
       )
 end
diff --git a/runtime/lua/vim/lsp/util.lua b/runtime/lua/vim/lsp/util.lua
index 3deec6d74e..f78a36fda2 100644
--- a/runtime/lua/vim/lsp/util.lua
+++ b/runtime/lua/vim/lsp/util.lua
@@ -1314,6 +1314,9 @@ function M.make_text_document_params()
   return { uri = vim.uri_from_bufnr(0) }
 end
 
+function M.make_workspace_params(added, removed)
+  return { event = { added = added; removed = removed; } }
+end
 --- Returns visual width of tabstop.
 ---
 --@see |softtabstop|