From 8783bea06e1e0dfa8dfd4834058923088471d832 Mon Sep 17 00:00:00 2001
From: TJ DeVries <devries.timothyj@gmail.com>
Date: Mon, 11 Jan 2021 13:29:37 -0500
Subject: feat: quickfix (#293)

* feat: quickfix (not implemented)

* [WIP]: Wed 09 Dec 2020 11:11:30 PM EST

* somewhat working linked list impl

* getting closer

* might be working

* might be working for real

* works and implemented basic example

* dont forget to close prompt

* fix descending and add more tests

* test fixes

* fix test

* more logging

* Fix some more tests

* Fix logging messing up tests

* fix: lint

* fix: multi select stuffs
---
 lua/telescope/pickers/scroller.lua | 93 +++++++++++++++++++++++---------------
 1 file changed, 56 insertions(+), 37 deletions(-)

(limited to 'lua/telescope/pickers/scroller.lua')

diff --git a/lua/telescope/pickers/scroller.lua b/lua/telescope/pickers/scroller.lua
index 324627b..3169c4b 100644
--- a/lua/telescope/pickers/scroller.lua
+++ b/lua/telescope/pickers/scroller.lua
@@ -1,56 +1,75 @@
 local scroller = {}
 
-local calc_count_fn = function(sorting_strategy)
-  if sorting_strategy == 'ascending' then
-    return function(a, b) return math.min(a, b) end
-  else
-    return function(a, b, row)
-      if a == b or not row then
-        return math.max(a, b)
-      else
-        local x = a - b
-        if row < x then
-          return math.max(a, b) - 1, true
-        elseif row == a then
-          return x, true
-        else
-          return math.max(a, b)
-        end
-      end
-    end
-  end
-end
+local range_calculators = {
+  ascending = function(max_results, num_results)
+    return 0, math.min(max_results, num_results)
+  end,
 
-scroller.create = function(strategy, sorting_strategy)
-  local calc_count = calc_count_fn(sorting_strategy)
+  descending = function(max_results, num_results)
+    return math.max(max_results - num_results, 0), max_results
+  end,
+}
 
-  if strategy == 'cycle' then
+local scroll_calculators = {
+  cycle = function(range_fn)
     return function(max_results, num_results, row)
-      local count, b = calc_count(max_results, num_results, row)
-      if b then return count end
+      local start, finish = range_fn(max_results, num_results)
 
-      if row >= count then
-        return 0
-      elseif row < 0 then
-        return count - 1
+      if row >= finish then
+        return start
+      elseif row < start then
+        return finish - 1
       end
 
       return row
     end
-  elseif strategy == 'limit' or strategy == nil then
+  end,
+
+  limit = function(range_fn)
     return function(max_results, num_results, row)
-      local count = calc_count(max_results, num_results)
+      local start, finish = range_fn(max_results, num_results)
 
-      if row >= count then
-        return count - 1
-      elseif row < 0 then
-        return 0
+      if row >= finish then
+        return finish - 1
+      elseif row < start then
+        return start
       end
 
       return row
     end
-  else
-    error("Unsupported strategy: " .. strategy)
+  end,
+}
+
+scroller.create = function(scroll_strategy, sorting_strategy)
+  local range_fn = range_calculators[sorting_strategy]
+  if not range_fn then
+    error(debug.traceback("Unknown sorting strategy: " .. sorting_strategy))
+  end
+
+  local scroll_fn = scroll_calculators[scroll_strategy]
+  if not scroll_fn then
+    error(debug.traceback("Unknown scroll strategy: " .. (scroll_strategy or '')))
+  end
+
+  local calculator = scroll_fn(range_fn)
+  return function(max_results, num_results, row)
+    local result = calculator(max_results, num_results, row)
+
+    if result < 0 then
+      error(string.format(
+        "Must never return a negative row: { result = %s, args = { %s %s %s } }",
+        result, max_results, num_results, row
+      ))
+    end
+
+    if result >= max_results then
+      error(string.format(
+        "Must never exceed max results: { result = %s, args = { %s %s %s } }",
+        result, max_results, num_results, row
+      ))
+    end
+
+    return result
   end
 end
 
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