From 3945dc5d00c203cbd485f3868bab1cd649ce7464 Mon Sep 17 00:00:00 2001
From: hrsh7th <hrsh7th@gmail.com>
Date: Fri, 29 Oct 2021 18:46:51 +0900
Subject: [PATCH] Add basic recently_used comparator

---
 README.md                  |  5 +++++
 lua/cmp/config/compare.lua | 16 +++++++++++++++
 lua/cmp/config/default.lua | 40 ++++++++++----------------------------
 lua/cmp/init.lua           | 11 ++++++++++-
 4 files changed, 41 insertions(+), 31 deletions(-)

diff --git a/README.md b/README.md
index 0d36701..752f8cd 100644
--- a/README.md
+++ b/README.md
@@ -360,6 +360,7 @@ Default:
   cmp.config.compare.offset,
   cmp.config.compare.exact,
   cmp.config.compare.score,
+  cmp.config.compare.recently_used,
   cmp.config.compare.kind,
   cmp.config.compare.sort_text,
   cmp.config.compare.length,
@@ -478,6 +479,10 @@ Subscribe the following events.
 
 - `confirm_done`
 
+#### `cmp.get_config()`
+
+Return the current configuration.
+
 #### `cmp.visible()`
 
 Return the completion menu is visible or not.
diff --git a/lua/cmp/config/compare.lua b/lua/cmp/config/compare.lua
index 48eca2b..51bdcfe 100644
--- a/lua/cmp/config/compare.lua
+++ b/lua/cmp/config/compare.lua
@@ -30,6 +30,22 @@ compare.score = function(entry1, entry2)
   end
 end
 
+-- recently_used
+compare.recently_used = setmetatable({
+  records = {},
+  add_entry = function(self, e)
+    self.records[e.completion_item.label] = vim.loop.now()
+  end
+}, {
+  __call = function(self, entry1, entry2)
+    local t1 = self.records[entry1.completion_item.label] or -1
+    local t2 = self.records[entry2.completion_item.label] or -1
+    if t1 ~= t2 then
+      return t1 > t2
+    end
+  end
+})
+
 -- kind
 compare.kind = function(entry1, entry2)
   local kind1 = entry1:get_kind()
diff --git a/lua/cmp/config/default.lua b/lua/cmp/config/default.lua
index 5779a09..28bf42d 100644
--- a/lua/cmp/config/default.lua
+++ b/lua/cmp/config/default.lua
@@ -47,34 +47,14 @@ return function()
     sorting = {
       priority_weight = 2,
       comparators = {
-        function(e1, e2)
-          local diff
-          diff = compare.offset(e1, e2)
-          if diff ~= nil then
-            return diff
-          end
-          diff = compare.exact(e1, e2)
-          if diff ~= nil then
-            return diff
-          end
-          diff = compare.score(e1, e2)
-          if diff ~= nil then
-            return diff
-          end
-          diff = compare.kind(e1, e2)
-          if diff ~= nil then
-            return diff
-          end
-          diff = compare.sort_text(e1, e2)
-          if diff ~= nil then
-            return diff
-          end
-          diff = compare.length(e1, e2)
-          if diff ~= nil then
-            return diff
-          end
-          return compare.order(e1, e2)
-        end,
+        compare.offset,
+        compare.exact,
+        compare.score,
+        compare.recently_used,
+        compare.kind,
+        compare.sort_text,
+        compare.length,
+        compare.order,
       },
     },
 
@@ -102,7 +82,7 @@ return function()
       ['<Tab>'] = mapping({
         c = function(fallback)
           local cmp = require('cmp')
-          if #cmp.core:get_sources() > 0 and not require('cmp.config').get().experimental.native_menu then
+          if #cmp.core:get_sources() > 0 and not cmp.get_config().experimental.native_menu then
             if cmp.visible() then
               cmp.select_next_item()
             else
@@ -116,7 +96,7 @@ return function()
       ['<S-Tab>'] = mapping({
         c = function(fallback)
           local cmp = require('cmp')
-          if #cmp.core:get_sources() > 0 and not require('cmp.config').get().experimental.native_menu then
+          if #cmp.core:get_sources() > 0 and not cmp.get_config().experimental.native_menu then
             if cmp.visible() then
               cmp.select_prev_item()
             else
diff --git a/lua/cmp/init.lua b/lua/cmp/init.lua
index cd93c3a..fe5461f 100644
--- a/lua/cmp/init.lua
+++ b/lua/cmp/init.lua
@@ -44,6 +44,12 @@ cmp.unregister_source = function(id)
   cmp.core:unregister_source(id)
 end
 
+---Get current configuration.
+---@return cmp.ConfigSchema
+cmp.get_config = function()
+  return require('cmp.config').get()
+end
+
 ---Invoke completion manually
 cmp.complete = function()
   cmp.core:complete(cmp.core:get_context({ reason = cmp.ContextReason.Manual }))
@@ -262,7 +268,6 @@ cmp.setup = setmetatable({
   end,
 })
 
----Handle events
 autocmd.subscribe('InsertEnter', function()
   -- Avoid unexpected mode detection (mode() function will returns `normal mode` on the InsertEnter event.)
   vim.schedule(function()
@@ -290,4 +295,8 @@ autocmd.subscribe('InsertLeave', function()
   cmp.core.view:close()
 end)
 
+cmp.event:on('confirm_done', function(e)
+  cmp.config.compare.recently_used:add_entry(e)
+end)
+
 return cmp