From 5d897901211330c16025aaf16eee0c2a1b715419 Mon Sep 17 00:00:00 2001
From: Joshua Reusch <jreusch4@gmail.com>
Date: Sat, 14 Sep 2024 20:53:13 +0200
Subject: [PATCH] ffi string_fold on js for performance

---
 bench/fstw.mjs           |  2 +-
 bench/sw.mjs             |  7 ++++---
 gleam.toml               |  2 +-
 src/string_width.gleam   | 20 +++++++++++++++-----
 src/string_width_ffi.mjs |  7 +++++++
 5 files changed, 28 insertions(+), 10 deletions(-)

diff --git a/bench/fstw.mjs b/bench/fstw.mjs
index b01ba46..dbe504e 100644
--- a/bench/fstw.mjs
+++ b/bench/fstw.mjs
@@ -1,4 +1,4 @@
-import _string_width from './node_modules/fast-string-truncated-width/dist/index.js'
+import _string_width from '../node_modules/fast-string-truncated-width/dist/index.js'
 const string_width = (input) => _string_width(input, {limit:Infinity, ellipsis:""}).width
 
 let sum = 0;
diff --git a/bench/sw.mjs b/bench/sw.mjs
index de3a454..0672867 100644
--- a/bench/sw.mjs
+++ b/bench/sw.mjs
@@ -1,8 +1,9 @@
-import { line as string_width } from './build/dev/javascript/string_width/string_width.mjs'
-import { toList } from './build/dev/javascript/string_width/gleam.mjs'
+import { line as string_width, HandleGraphemeClusters } from '../build/dev/javascript/string_width/string_width.mjs'
+import { toList } from '../build/dev/javascript/string_width/gleam.mjs'
 
 let sum = 0;
+let options = toList([new HandleGraphemeClusters()]);
 for(let i = 0; i < 10000; ++i) {
-  sum += string_width("\x1b[1;95m· \x1b[0m\x1b[K\x1b[33mdeno\x1b[0m\x1b[K, \x1b[33mtypescript\x1b[0m\x1b[K, \x1b[33mts\x1b[0m\x1b[K", toList([]))
+  sum += string_width("\x1b[1;95m· \x1b[0m\x1b[K\x1b[33mdeno\x1b[0m\x1b[K, \x1b[33mtypescript\x1b[0m\x1b[K, \x1b[33mts\x1b[0m\x1b[K", options)
 }
 console.log(sum)
diff --git a/gleam.toml b/gleam.toml
index bebb538..2579409 100644
--- a/gleam.toml
+++ b/gleam.toml
@@ -1,5 +1,5 @@
 name = "string_width"
-version = "2.0.2"
+version = "2.0.3"
 
 description = "Estimate the dimensions of a string when printed in the terminal."
 licences = ["BSD-3-Clause"]
diff --git a/src/string_width.gleam b/src/string_width.gleam
index 6d702ce..03f5fa8 100644
--- a/src/string_width.gleam
+++ b/src/string_width.gleam
@@ -121,12 +121,22 @@ pub fn dimensions(str: String, options: List(Option)) -> #(Int, Int) {
 }
 
 fn graphemes_width(options: Options, str: String, width: Int) {
+  use width, grapheme <- string_fold(str, width)
+  width + do_grapheme_cluster(options, grapheme)
+  // case string.pop_grapheme(str) {
+  //   Ok(#(grapheme, str)) -> {
+  //     let grapheme_width = do_grapheme_cluster(options, grapheme)
+  //     graphemes_width(options, str, width + grapheme_width)
+  //   }
+  //   Error(Nil) -> width
+  // }
+}
+
+@external(javascript, "./string_width_ffi.mjs", "string_fold")
+fn string_fold(str: String, state: a, fun: fn(a, String) -> a) -> a {
   case string.pop_grapheme(str) {
-    Ok(#(grapheme, str)) -> {
-      let grapheme_width = do_grapheme_cluster(options, grapheme)
-      graphemes_width(options, str, width + grapheme_width)
-    }
-    Error(Nil) -> width
+    Ok(#(grapheme, str)) -> string_fold(str, fun(state, grapheme), fun)
+    Error(Nil) -> state
   }
 }
 
diff --git a/src/string_width_ffi.mjs b/src/string_width_ffi.mjs
index e32acda..830aa86 100644
--- a/src/string_width_ffi.mjs
+++ b/src/string_width_ffi.mjs
@@ -9,3 +9,10 @@ export function table_lookup(table, value) {
   return ((table.byteAt(table.byteAt(hi) * 32 + md) >> lo) & 1) > 0;
 }
 
+const segmenter = new Intl.Segmenter();
+export function string_fold(str, state, fun) {
+  for(const { segment } of segmenter.segment(str)) {
+    state = fun(state, segment)
+  }
+  return state
+}
-- 
2.51.2