From 28b41de2f491ef598197823c04fc7e86ae76a625 Mon Sep 17 00:00:00 2001
From: Akianonymus <anonymus.aki@gmail.com>
Date: Sun, 28 Aug 2022 12:30:35 +0530
Subject: fragment | Implement better autocmd management | refactor

add a all_buffers option - colorizer will activate on all buffers, empty or not, still respect filetypes option

handle errors when detach is called multiple times from the same buffer

use bufdelete and bufdelete to remove the autocmds

use a more efficient compile parse_fn function

use custom ldoc template to generate vim help
---
 lua/colorizer/utils.lua | 106 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 106 insertions(+)
 create mode 100644 lua/colorizer/utils.lua

(limited to 'lua/colorizer/utils.lua')

diff --git a/lua/colorizer/utils.lua b/lua/colorizer/utils.lua
new file mode 100644
index 0000000..0cb09ee
--- /dev/null
+++ b/lua/colorizer/utils.lua
@@ -0,0 +1,106 @@
+---Helper utils
+--@module utils
+local bit, ffi = require "bit", require "ffi"
+local band, bor, rshift, lshift = bit.band, bit.bor, bit.rshift, bit.lshift
+
+-- -- TODO use rgb as the return value from the matcher functions
+-- -- instead of the rgb_hex. Can be the highlight key as well
+-- -- when you shift it left 8 bits. Use the lower 8 bits for
+-- -- indicating which highlight mode to use.
+-- ffi.cdef [[
+-- typedef struct { uint8_t r, g, b; } colorizer_rgb;
+-- ]]
+-- local rgb_t = ffi.typeof 'colorizer_rgb'
+
+-- Create a lookup table where the bottom 4 bits are used to indicate the
+-- category and the top 4 bits are the hex value of the ASCII byte.
+local BYTE_CATEGORY = ffi.new "uint8_t[256]"
+local CATEGORY_DIGIT = lshift(1, 0)
+local CATEGORY_ALPHA = lshift(1, 1)
+local CATEGORY_HEX = lshift(1, 2)
+local CATEGORY_ALPHANUM = bor(CATEGORY_ALPHA, CATEGORY_DIGIT)
+
+-- do not run the loop multiple times
+local b = string.byte
+for i = 0, 255 do
+  local v = 0
+  -- Digit is bit 1
+  if i >= b "0" and i <= b "9" then
+    v = bor(v, lshift(1, 0))
+    v = bor(v, lshift(1, 2))
+    v = bor(v, lshift(i - b "0", 4))
+  end
+  local lowercase = bor(i, 0x20)
+  -- Alpha is bit 2
+  if lowercase >= b "a" and lowercase <= b "z" then
+    v = bor(v, lshift(1, 1))
+    if lowercase <= b "f" then
+      v = bor(v, lshift(1, 2))
+      v = bor(v, lshift(lowercase - b "a" + 10, 4))
+    end
+  end
+  BYTE_CATEGORY[i] = v
+end
+
+---Obvious.
+---@param byte number
+---@return boolean
+local function byte_is_alphanumeric(byte)
+  local category = BYTE_CATEGORY[byte]
+  return band(category, CATEGORY_ALPHANUM) ~= 0
+end
+
+---Obvious.
+---@param byte number
+---@return boolean
+local function byte_is_hex(byte)
+  return band(BYTE_CATEGORY[byte], CATEGORY_HEX) ~= 0
+end
+
+---Merge two tables.
+--
+-- todo: Remove this and use `vim.tbl_deep_extend`
+---@return table
+local function merge(...)
+  local res = {}
+  for i = 1, select("#", ...) do
+    local o = select(i, ...)
+    if type(o) ~= "table" then
+      return {}
+    end
+    for k, v in pairs(o) do
+      res[k] = v
+    end
+  end
+  return res
+end
+
+--- Obvious.
+---@param byte number
+---@return number
+local function parse_hex(byte)
+  return rshift(BYTE_CATEGORY[byte], 4)
+end
+
+--- Obvious.
+---@param v string
+---@return number|nil
+local function percent_or_hex(v)
+  if v:sub(-1, -1) == "%" then
+    return tonumber(v:sub(1, -2)) / 100 * 255
+  end
+  local x = tonumber(v)
+  if x > 255 then
+    return
+  end
+  return x
+end
+
+--- @export
+return {
+  byte_is_alphanumeric = byte_is_alphanumeric,
+  byte_is_hex = byte_is_hex,
+  merge = merge,
+  parse_hex = parse_hex,
+  percent_or_hex = percent_or_hex,
+}
-- 
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