perf(vim.text): use lookup table implementation for hex encoding (#30080)

Co-authored-by: glepnir <glephunter@gmail.com>

1 files changed, 52 insertions, 0 deletions

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)