feat(lua): add noref to deepcopy

Problem:

Currently `deepcopy` hashes every single tables it copies so it can be
reused. For tables of mostly unique items that are non recursive, this
hashing is unnecessarily expensive

Solution:

Port the `noref` argument from Vimscripts `deepcopy()`.

The below benchmark demonstrates the results for two extreme cases of
tables of different sizes. One table that uses the same table lots of
times and one with all unique tables.

| test                 | `noref=false` (ms) | `noref=true` (ms) |
| -------------------- | ------------------ | ----------------- |
| unique tables (50)   | 6.59               | 2.62              |
| shared tables (50)   | 3.24               | 6.40              |
| unique tables (2000) | 23381.48           | 2884.53           |
| shared tables (2000) | 3505.54            | 14038.80          |

The results are basically the inverse of each other where `noref` is
much more performance on tables with unique fields, and `not noref` is
more performant on tables that reuse fields.

1 files changed, 6 insertions, 6 deletions

diff --git a/runtime/lua/vim/diagnostic.lua b/runtime/lua/vim/diagnostic.lua
index a447463dff..897837a5ce 100644
--- a/runtime/lua/vim/diagnostic.lua
+++ b/runtime/lua/vim/diagnostic.lua
@@ -134,7 +134,7 @@ local function prefix_source(diagnostics)
       return d
     end
 
-    local t = vim.deepcopy(d)
+    local t = vim.deepcopy(d, true)
     t.message = string.format('%s: %s', d.source, d.message)
     return t
   end, diagnostics)
@@ -146,7 +146,7 @@ local function reformat_diagnostics(format, diagnostics)
     diagnostics = { diagnostics, 't' },
   })
 
-  local formatted = vim.deepcopy(diagnostics)
+  local formatted = vim.deepcopy(diagnostics, true)
   for _, diagnostic in ipairs(formatted) do
     diagnostic.message = format(diagnostic)
   end
@@ -373,7 +373,7 @@ local function get_diagnostics(bufnr, opts, clamp)
           or d.col < 0
           or d.end_col < 0
         then
-          d = vim.deepcopy(d)
+          d = vim.deepcopy(d, true)
           d.lnum = math.max(math.min(d.lnum, line_count), 0)
           d.end_lnum = math.max(math.min(d.end_lnum, line_count), 0)
           d.col = math.max(d.col, 0)
@@ -636,7 +636,7 @@ function M.config(opts, namespace)
 
   if not opts then
     -- Return current config
-    return vim.deepcopy(t)
+    return vim.deepcopy(t, true)
   end
 
   for k, v in pairs(opts) do
@@ -723,7 +723,7 @@ end
 ---
 ---@return table A list of active diagnostic namespaces |vim.diagnostic|.
 function M.get_namespaces()
-  return vim.deepcopy(all_namespaces)
+  return vim.deepcopy(all_namespaces, true)
 end
 
 ---@class Diagnostic
@@ -756,7 +756,7 @@ function M.get(bufnr, opts)
     opts = { opts, 't', true },
   })
 
-  return vim.deepcopy(get_diagnostics(bufnr, opts, false))
+  return vim.deepcopy(get_diagnostics(bufnr, opts, false), true)
 end
 
 --- Get current diagnostics count.