From 6c1a88471fc6444ee93d6ca0c64d0953a0d857ac Mon Sep 17 00:00:00 2001
From: Jose Colon Rodriguez
Date: Sat, 17 Feb 2024 09:50:50 -0400
Subject: GraphemeIterator ASCII optimization 3x faster

---
 src/Grapheme.zig | 79 ++++++++++++++++++++++++++++++--------------------------
 1 file changed, 42 insertions(+), 37 deletions(-)

(limited to 'src/Grapheme.zig')

diff --git a/src/Grapheme.zig b/src/Grapheme.zig
index 888fcd4..6892a2a 100644
--- a/src/Grapheme.zig
+++ b/src/Grapheme.zig
@@ -45,9 +45,14 @@ pub const GraphemeIterator = struct {
     pub fn next(self: *Self) ?Grapheme {
         self.advance();
 
-        // If at end
+        // If no more
         if (self.buf[0] == null) return null;
+        // If last one
         if (self.buf[1] == null) return Grapheme{ .len = self.buf[0].?.len, .offset = self.buf[0].?.offset };
+        // If ASCII
+        if (self.buf[0].?.code != '\r' and self.buf[0].?.code < 128 and self.buf[1].?.code < 128) {
+            return Grapheme{ .len = self.buf[0].?.len, .offset = self.buf[0].?.offset };
+        }
 
         const gc_start = self.buf[0].?.offset;
         var gc_len: usize = self.buf[0].?.len;
@@ -89,42 +94,6 @@ fn isIgnorable(cp: u21) bool {
     return cp_gbp_prop == .extend or cp_gbp_prop == .spacing or cp == '\u{200d}';
 }
 
-test "Segmentation comptime GraphemeIterator" {
-    const want = [_][]const u8{ "H", "é", "l", "l", "o" };
-
-    comptime {
-        const src = "Héllo";
-        var ct_iter = GraphemeIterator.init(src);
-        var i = 0;
-        while (ct_iter.next()) |grapheme| : (i += 1) {
-            try std.testing.expect(grapheme.eql(src, want[i]));
-        }
-    }
-}
-
-test "Segmentation ZWJ and ZWSP emoji sequences" {
-    const seq_1 = "\u{1F43B}\u{200D}\u{2744}\u{FE0F}";
-    const seq_2 = "\u{1F43B}\u{200D}\u{2744}\u{FE0F}";
-    const with_zwj = seq_1 ++ "\u{200D}" ++ seq_2;
-    const with_zwsp = seq_1 ++ "\u{200B}" ++ seq_2;
-    const no_joiner = seq_1 ++ seq_2;
-
-    var ct_iter = GraphemeIterator.init(with_zwj);
-    var i: usize = 0;
-    while (ct_iter.next()) |_| : (i += 1) {}
-    try std.testing.expectEqual(@as(usize, 1), i);
-
-    ct_iter = GraphemeIterator.init(with_zwsp);
-    i = 0;
-    while (ct_iter.next()) |_| : (i += 1) {}
-    try std.testing.expectEqual(@as(usize, 3), i);
-
-    ct_iter = GraphemeIterator.init(no_joiner);
-    i = 0;
-    while (ct_iter.next()) |_| : (i += 1) {}
-    try std.testing.expectEqual(@as(usize, 2), i);
-}
-
 // Grapheme break state.
 // Extended Pictographic (emoji)
 fn hasXpic(state: *const u3) bool {
@@ -322,3 +291,39 @@ test "Segmentation GraphemeIterator" {
         }
     }
 }
+
+test "Segmentation comptime GraphemeIterator" {
+    const want = [_][]const u8{ "H", "é", "l", "l", "o" };
+
+    comptime {
+        const src = "Héllo";
+        var ct_iter = GraphemeIterator.init(src);
+        var i = 0;
+        while (ct_iter.next()) |grapheme| : (i += 1) {
+            try std.testing.expect(grapheme.eql(src, want[i]));
+        }
+    }
+}
+
+test "Segmentation ZWJ and ZWSP emoji sequences" {
+    const seq_1 = "\u{1F43B}\u{200D}\u{2744}\u{FE0F}";
+    const seq_2 = "\u{1F43B}\u{200D}\u{2744}\u{FE0F}";
+    const with_zwj = seq_1 ++ "\u{200D}" ++ seq_2;
+    const with_zwsp = seq_1 ++ "\u{200B}" ++ seq_2;
+    const no_joiner = seq_1 ++ seq_2;
+
+    var ct_iter = GraphemeIterator.init(with_zwj);
+    var i: usize = 0;
+    while (ct_iter.next()) |_| : (i += 1) {}
+    try std.testing.expectEqual(@as(usize, 1), i);
+
+    ct_iter = GraphemeIterator.init(with_zwsp);
+    i = 0;
+    while (ct_iter.next()) |_| : (i += 1) {}
+    try std.testing.expectEqual(@as(usize, 3), i);
+
+    ct_iter = GraphemeIterator.init(no_joiner);
+    i = 0;
+    while (ct_iter.next()) |_| : (i += 1) {}
+    try std.testing.expectEqual(@as(usize, 2), i);
+}
-- 
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