From 771726f7d6e7e96e9273e454b1c1f49168663a37 Mon Sep 17 00:00:00 2001
From: JINNOUCHI Yasushi <me@delphinus.dev>
Date: Sun, 25 Feb 2024 14:25:40 +0900
Subject: [PATCH] feat: match like 'smartcase' (#177)

* feat: match like 'smartcase'

Fix #36

* docs: add note for 'smartcase'

* docs: emphasize requirements
---
 README.md                | 16 +++++++++-
 lua/frecency/picker.lua  |  4 +--
 lua/frecency/sorters.lua | 63 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 80 insertions(+), 3 deletions(-)
 create mode 100644 lua/frecency/sorters.lua

diff --git a/README.md b/README.md
index 4b10ea0..836c0ba 100644
--- a/README.md
+++ b/README.md
@@ -77,7 +77,7 @@ directories provided by the language server.
 
 ## Requirements
 
-- [telescope.nvim](https://github.com/nvim-telescope/telescope.nvim) (required)
+- [telescope.nvim](https://github.com/nvim-telescope/telescope.nvim) **(required)**
 - [nvim-web-devicons](https://github.com/kyazdani42/nvim-web-devicons) (optional)
 - [ripgrep](https://github.com/BurntSushi/ripgrep) or [fd](https://github.com/sharkdp/fd) (optional)
 
@@ -142,6 +142,20 @@ Filter tags are applied by typing the `:tag:` name (adding surrounding colons)
 in the finder query. Entering `:<Tab>` will trigger omnicompletion for
 available tags.
 
+### Dealing with upper case letters
+
+In default, the sorter always ignores upper case letters in your input string.
+But when [`'smartcase'`][smartcase] is ON and input string includes one upper case letter at
+least, it matches against exact the same as you input.
+
+| input string | `'smartcase'` is ON          | `'smartcase'` is OFF        |
+|--------------|-----------------------------|-----------------------------|
+| `abc`        | matches `abc`, `ABC`, `aBc` | matches `abc`, `ABC`, `aBc` |
+| `aBc`        | matches `aBc`               | no match                    |
+| `ABC`        | matches `ABC`               | no match                    |
+
+[smartcase]: https://neovim.io/doc/user/options.html#'smartcase'
+
 ## Configuration
 
 See [default configuration](https://github.com/nvim-telescope/telescope.nvim#telescope-defaults) for full details on configuring Telescope.
diff --git a/lua/frecency/picker.lua b/lua/frecency/picker.lua
index edf3f9f..79bf216 100644
--- a/lua/frecency/picker.lua
+++ b/lua/frecency/picker.lua
@@ -1,11 +1,11 @@
 local State = require "frecency.state"
 local Finder = require "frecency.finder"
+local sorters = require "frecency.sorters"
 local log = require "plenary.log"
 local Path = require "plenary.path" --[[@as PlenaryPath]]
 local actions = require "telescope.actions"
 local config_values = require("telescope.config").values
 local pickers = require "telescope.pickers"
-local sorters = require "telescope.sorters"
 local utils = require "telescope.utils" --[[@as TelescopeUtils]]
 local uv = vim.loop or vim.uv
 
@@ -110,7 +110,7 @@ function Picker:start(opts)
     prompt_title = "Frecency",
     finder = finder,
     previewer = config_values.file_previewer(opts),
-    sorter = sorters.get_substr_matcher(),
+    sorter = sorters.get_frecency_matcher(),
     on_input_filter_cb = self:on_input_filter_cb(opts),
     attach_mappings = function(prompt_bufnr)
       return self:attach_mappings(prompt_bufnr)
diff --git a/lua/frecency/sorters.lua b/lua/frecency/sorters.lua
new file mode 100644
index 0000000..98b8b70
--- /dev/null
+++ b/lua/frecency/sorters.lua
@@ -0,0 +1,63 @@
+local sorters = require "telescope.sorters"
+local util = require "telescope.utils"
+
+local M = {}
+
+---@param prompt string
+---@return boolean
+local function has_upper_case(prompt)
+  return not not prompt:match "%u"
+end
+
+---@param prompt string
+---@param display string
+---@return { start: integer, finish: integer }[]
+local function highlighter(_, prompt, display)
+  ---@type { start: integer, finish: integer }[]
+  local highlights = {}
+  display = has_upper_case(prompt) and display or display:lower()
+
+  local search_terms = util.max_split(prompt, "%s")
+  local hl_start, hl_end
+
+  for _, word in ipairs(search_terms) do
+    hl_start, hl_end = display:find(word, 1, true)
+    if hl_start then
+      table.insert(highlights, { start = hl_start, finish = hl_end })
+    end
+  end
+
+  return highlights
+end
+
+---@param prompt string
+---@param entry FrecencyEntry
+---@return integer
+local function scoring_function(_, prompt, _, entry)
+  if #prompt == 0 then
+    return 1
+  end
+
+  local display = has_upper_case(prompt) and entry.ordinal or entry.ordinal:lower()
+
+  local search_terms = util.max_split(prompt, "%s")
+  for _, word in ipairs(search_terms) do
+    if not display:find(word, 1, true) then
+      return -1
+    end
+  end
+  return entry.index
+end
+
+---This is a sorter similar to telescope.sorters.get_substr_matcher. telescope's
+---one always ignore cases, but this sorter deal with them like 'smartcase' way.
+function M.get_frecency_matcher()
+  return vim.o.smartcase
+      and sorters.Sorter:new {
+        highlighter = highlighter,
+        scoring_function = scoring_function,
+      }
+    or sorters.get_substr_matcher()
+end
+
+return M