From 99b5ffd688247f25295f3dd06e57c0d9ad85b072 Mon Sep 17 00:00:00 2001 From: Gregory Anders <greg@gpanders.com> Date: Tue, 26 Nov 2024 13:56:01 -0600 Subject: [PATCH] perf(vim.text): use lookup table implementation for hex encoding (#30080) Co-authored-by: glepnir <glephunter@gmail.com> --- runtime/lua/vim/text.lua | 24 ++++++++++++-- test/benchmark/text_spec.lua | 52 +++++++++++++++++++++++++++++++ test/functional/lua/text_spec.lua | 16 ++++++++++ 3 files changed, 89 insertions(+), 3 deletions(-) create mode 100644 test/benchmark/text_spec.lua diff --git a/runtime/lua/vim/text.lua b/runtime/lua/vim/text.lua index d45c8021c6..f910ab3a1d 100644 --- a/runtime/lua/vim/text.lua +++ b/runtime/lua/vim/text.lua @@ -2,6 +2,18 @@ local M = {} +local alphabet = '0123456789ABCDEF' +local atoi = {} ---@type table<string, integer> +local itoa = {} ---@type table<integer, string> +do + for i = 1, #alphabet do + local char = alphabet:sub(i, i) + itoa[i - 1] = char + atoi[char] = i - 1 + atoi[char:lower()] = i - 1 + end +end + --- Hex encode a string. --- --- @param str string String to encode @@ -9,7 +21,9 @@ local M = {} function M.hexencode(str) local enc = {} ---@type string[] for i = 1, #str do - enc[i] = string.format('%02X', str:byte(i, i + 1)) + local byte = str:byte(i) + enc[2 * i - 1] = itoa[math.floor(byte / 16)] + enc[2 * i] = itoa[byte % 16] end return table.concat(enc) end @@ -26,8 +40,12 @@ function M.hexdecode(enc) local str = {} ---@type string[] for i = 1, #enc, 2 do - local n = assert(tonumber(enc:sub(i, i + 1), 16)) - str[#str + 1] = string.char(n) + local u = atoi[enc:sub(i, i)] + local l = atoi[enc:sub(i + 1, i + 1)] + if not u or not l then + return nil, 'string must contain only hex characters' + end + str[(i + 1) / 2] = string.char(u * 16 + l) end return table.concat(str), nil end diff --git a/test/benchmark/text_spec.lua b/test/benchmark/text_spec.lua new file mode 100644 index 0000000000..9cfeaf765b --- /dev/null +++ b/test/benchmark/text_spec.lua @@ -0,0 +1,52 @@ +describe('vim.text', function() + --- @param t number[] + local function mean(t) + assert(#t > 0) + local sum = 0 + for _, v in ipairs(t) do + sum = sum + v + end + return sum / #t + end + + --- @param t number[] + local function median(t) + local len = #t + if len % 2 == 0 then + return t[len / 2] + end + return t[(len + 1) / 2] + end + + --- @param f fun(t: number[]): table<number, number|string|table> + local function measure(f, input, N) + local stats = {} ---@type number[] + for _ = 1, N do + local tic = vim.uv.hrtime() + f(input) + local toc = vim.uv.hrtime() + stats[#stats + 1] = (toc - tic) / 1000000 + end + table.sort(stats) + print( + string.format( + '\nN: %d, Min: %0.6f ms, Max: %0.6f ms, Median: %0.6f ms, Mean: %0.6f ms', + N, + math.min(unpack(stats)), + math.max(unpack(stats)), + median(stats), + mean(stats) + ) + ) + end + + local input, output = string.rep('😂', 2 ^ 16), string.rep('F09F9882', 2 ^ 16) + + it('hexencode', function() + measure(vim.text.hexencode, input, 100) + end) + + it('hexdecode', function() + measure(vim.text.hexdecode, output, 100) + end) +end) diff --git a/test/functional/lua/text_spec.lua b/test/functional/lua/text_spec.lua index be471bfd62..dd08a6ec04 100644 --- a/test/functional/lua/text_spec.lua +++ b/test/functional/lua/text_spec.lua @@ -26,5 +26,21 @@ describe('vim.text', function() eq(output, vim.text.hexencode(input)) eq(input, vim.text.hexdecode(output)) end) + + it('errors on invalid input', function() + -- Odd number of hex characters + do + local res, err = vim.text.hexdecode('ABC') + eq(nil, res) + eq('string must have an even number of hex characters', err) + end + + -- Non-hexadecimal input + do + local res, err = vim.text.hexdecode('nothex') + eq(nil, res) + eq('string must contain only hex characters', err) + end + end) end) end)