Add fuzzy git file finderZ

lua/telescope/sorters.lua

@@ -1,3 +1,5 @@
+local ceil = math.ceil
+
 local log = require('telescope.log')
 local util = require('telescope.utils')
 
@@ -70,4 +72,80 @@ sorters.get_levenshtein_sorter = function()
   }
 end
 
+sorters.get_norcalli_sorter = function()
+  local ngramlen = 2
+
+  local cached_ngrams = {}
+
+  local function overlapping_ngrams(s, n)
+    if cached_ngrams[s] and cached_ngrams[s][n] then
+      return cached_ngrams[s][n]
+    end
+
+    local R = {}
+    for i = 1, s:len() - n + 1 do
+      R[#R+1] = s:sub(i, i+n-1)
+    end
+
+    if not cached_ngrams[s] then
+      cached_ngrams[s] = {}
+    end
+
+    cached_ngrams[s][n] = R
+
+    return R
+  end
+
+  return Sorter:new {
+    scoring_function = function(_, prompt, line)
+      if prompt == 0 or #prompt < ngramlen then
+        return 0
+      end
+
+      local prompt_ngrams = overlapping_ngrams(prompt, ngramlen)
+
+      local prompt_lower = prompt:lower()
+      local line_lower = line:lower()
+
+      local N = #prompt
+
+      local contains_string = line_lower:find(prompt_lower, 1, true)
+
+      local consecutive_matches = 0
+      local previous_match_index = 0
+      local match_count = 0
+
+      for i = 1, #prompt_ngrams do
+        local match_start = line_lower:find(prompt_ngrams[i], 1, true)
+        if match_start then
+          match_count = match_count + 1
+          if match_start > previous_match_index then
+            consecutive_matches = consecutive_matches + 1
+          end
+
+          previous_match_index = match_start
+        end
+      end
+
+      -- TODO: Copied from ashkan.
+      local denominator = (
+        (10 * match_count / #prompt_ngrams)
+        -- biases for shorter strings
+        -- TODO(ashkan): this can bias towards repeated finds of the same
+        -- subpattern with overlapping_ngrams
+        + 3 * match_count * ngramlen / #line
+        + consecutive_matches
+        + N / (contains_string or (2 * #line))
+        -- + 30/(c1 or 2*N)
+      )
+
+      if denominator == 0 or denominator ~= denominator then
+        return -1
+      end
+
+      return 1 / denominator
+    end
+  }
+end
+
 return sorters