From 992b72de0214aeb30d58b3821edb748b1f451e90 Mon Sep 17 00:00:00 2001
From: Senghan Bright <senghan.bright@deltaprojects.com>
Date: Thu, 14 Jan 2021 20:56:56 +0100
Subject: [PATCH] switch to substring matcher (WIP)

---
 lua/telescope/_extensions/frecency.lua        |  5 +--
 lua/telescope/_extensions/frecency/sorter.lua | 33 ++++++++++++++-----
 2 files changed, 27 insertions(+), 11 deletions(-)

diff --git a/lua/telescope/_extensions/frecency.lua b/lua/telescope/_extensions/frecency.lua
index c143c05..68c2da2 100644
--- a/lua/telescope/_extensions/frecency.lua
+++ b/lua/telescope/_extensions/frecency.lua
@@ -71,8 +71,9 @@ local frecency = function(opts)
         }
       end,
     },
-    previewer = conf.file_previewer(opts),
-    sorter    = sorters.get_frecency_sorter(opts),
+    -- previewer = conf.file_previewer(opts),
+    sorter    = sorters.get_substr_matcher(opts),
+    -- sorter    = conf.file_sorter(opts)
   }):find()
 end
 
diff --git a/lua/telescope/_extensions/frecency/sorter.lua b/lua/telescope/_extensions/frecency/sorter.lua
index 1821cb0..39b38a3 100644
--- a/lua/telescope/_extensions/frecency/sorter.lua
+++ b/lua/telescope/_extensions/frecency/sorter.lua
@@ -2,16 +2,31 @@ local sorters = require "telescope.sorters"
 
 local my_sorters = {}
 
-my_sorters.get_frecency_sorter = function(opts)
+
+local substr_highlighter = function(_, prompt, display)
+  local highlights = {}
+  display = display:lower()
+
+  local hl_start, hl_end
+  hl_start, hl_end = display:find(prompt, 1, true)
+  if hl_start then
+    table.insert(highlights, {start = hl_start, finish = hl_end})
+  end
+
+  return highlights
+end
+
+my_sorters.get_substr_matcher = function(opts)
   opts = opts or {}
-  opts.ngram_len = 2
 
-  local fuzzy_sorter = sorters.get_generic_fuzzy_sorter(opts)
+  local substr = sorters:new()
+  substr.highlighter = substr_highlighter
+  substr.scoring_function = function(_, prompt, _, entry)
+    -- local base_score = frecency:score(prompt, entry)
+    local base_score
 
-  local frecency = sorters:new()
-  frecency.highlighter = fuzzy_sorter.highlighter
-  frecency.scoring_function = function(_, prompt, _, entry)
-    local base_score = fuzzy_sorter:score(prompt, entry)
+    -- TODO: split the prompt into components
+    base_score = entry.name:find(prompt, 1, true) and 1 or -1
 
     if base_score == -1 then
       return -1
@@ -20,11 +35,11 @@ my_sorters.get_frecency_sorter = function(opts)
     if base_score == 0 then
       return entry.index
     else
-      return math.min(math.pow(entry.index, 0.25), 2) * base_score
+      return entry.index
     end
   end
 
-  return frecency
+  return substr
 end
 
 return my_sorters