From 1b355b08341c990f59b6e6e98c58d4e7357efd35 Mon Sep 17 00:00:00 2001
From: johnlevidy <jlevidy@directmatchx.com>
Date: Sat, 20 Apr 2024 13:30:42 -0400
Subject: [PATCH] feat: allow users to supply custom distance functions #66
 (#67)

* feat: allow users to supply custom distance functions #66

* docs:add the docs and read wise method

---------

Co-authored-by: mohsen <smoka7@hotmail.com>
---
 doc/hop.txt             | 10 ++++++++++
 lua/hop/defaults.lua    |  1 +
 lua/hop/hint.lua        | 19 +++++++++++++++++++
 lua/hop/jump_target.lua | 12 +-----------
 4 files changed, 31 insertions(+), 11 deletions(-)

diff --git a/doc/hop.txt b/doc/hop.txt
index 988bac9..4484724 100644
--- a/doc/hop.txt
+++ b/doc/hop.txt
@@ -720,6 +720,16 @@ below.
     
     Defaults:~
         `x_bias = 10`
+            
+    `distance_method`                                  *hop-config-distance_method*
+    This Determines the method which hops uses to evaluate the distance between 
+    jump target and the cursor.
+
+    We currently provide two `manh_distance` and `readwise_distance`
+     distance methods in `hint` module.
+
+    Defaults:~
+        `distance_method = require('hop.hint').manh_distance`
 
 `teasing`                                                     *hop-config-teasing*
     Boolean value stating whether Hop should tease you when you do something
diff --git a/lua/hop/defaults.lua b/lua/hop/defaults.lua
index e0bfc95..3666c75 100644
--- a/lua/hop/defaults.lua
+++ b/lua/hop/defaults.lua
@@ -10,6 +10,7 @@ M.quit_key = '<Esc>'
 M.perm_method = require('hop.perm').TrieBacktrackFilling
 M.reverse_distribution = false
 M.x_bias = 10
+M.distance_method = hint.manh_distance
 M.teasing = true
 M.virtual_cursor = false
 M.jump_on_sole_occurrence = true
diff --git a/lua/hop/hint.lua b/lua/hop/hint.lua
index 86b4dd0..b1d5d0f 100644
--- a/lua/hop/hint.lua
+++ b/lua/hop/hint.lua
@@ -49,6 +49,25 @@ M.HintPriority = {
   CURSOR = 65535,
 }
 
+-- Manhattan distance with column and row, weighted on x so that results are more packed on y.
+---@param a CursorPos
+---@param b CursorPos
+---@param x_bias number
+---@return number
+function M.manh_distance(a, b, x_bias)
+  return (x_bias * math.abs(b.row - a.row)) + math.abs(b.col - a.col)
+end
+
+--- Distance method that prioritises hints based on the
+--- left to right reading distance
+---@param a CursorPos Cursor Position
+---@param b CursorPos Jump target position
+---@param x_bias number
+---@return number 
+function M.readwise_distance(a, b, x_bias)
+  return (100 * math.abs(b.row - a.row)) + (b.col - a.col)
+end
+
 -- Reduce a hint.
 -- This function will remove hints not starting with the input key and will reduce the other ones
 -- with one level.
diff --git a/lua/hop/jump_target.lua b/lua/hop/jump_target.lua
index b0105b6..59ea051 100644
--- a/lua/hop/jump_target.lua
+++ b/lua/hop/jump_target.lua
@@ -32,15 +32,6 @@ local window = require('hop.window')
 ---@class JumpTargetModule
 local M = {}
 
--- Manhattan distance with column and row, weighted on x so that results are more packed on y.
----@param a CursorPos
----@param b CursorPos
----@param x_bias number
----@return number
-local function manh_dist(a, b, x_bias)
-  return (x_bias * math.abs(b.row - a.row)) + math.abs(b.col - a.col)
-end
-
 -- Create jump targets within line
 ---@param jump_ctx JumpContext
 ---@param opts Options
@@ -113,10 +104,9 @@ local function create_line_indirect_jump_targets(jump_ctx, locations, opts)
   local win_bias = math.abs(vim.api.nvim_get_current_win() - jump_ctx.win_ctx.win_handle) * 1000
   for _, jump_target in pairs(line_jump_targets) do
     locations.jump_targets[#locations.jump_targets + 1] = jump_target
-
     locations.indirect_jump_targets[#locations.indirect_jump_targets + 1] = {
       index = #locations.jump_targets,
-      score = manh_dist(jump_ctx.win_ctx.cursor, jump_target.cursor, opts.x_bias) + win_bias,
+      score = opts.distance_method(jump_ctx.win_ctx.cursor, jump_target.cursor, opts.x_bias) + win_bias,
     }
   end
 end