trying a bunch of things to get performance to match

src/build/UnicodeTables.zig

@@ -24,14 +24,16 @@ pub fn init(b: *std.Build, uucode_tables_zig: std.Build.LazyPath) !UnicodeTables
     if (b.lazyDependency("uucode", .{
         .target = b.graph.host,
         .@"tables.zig" = uucode_tables_zig,
+        .build_config_path = b.path("src/build/uucode_config.zig"),
     })) |dep| {
         exe.root_module.addImport("uucode", dep.module("uucode"));
     }
 
     const run = b.addRunArtifact(exe);
+    const output = run.addOutputFileArg("tables.zig");
     return .{
         .exe = exe,
-        .output = run.captureStdOut(),
+        .output = output,
     };
 }
 

src/build/uucode_config.zig

@@ -3,6 +3,93 @@ const config_x = @import("config.x.zig");
 const d = config.default;
 const wcwidth = config_x.wcwidth;
 
+pub const log_level = .debug;
+
+fn computeWidth(cp: u21, data: anytype, backing: anytype, tracking: anytype) void {
+    _ = cp;
+    _ = backing;
+    _ = tracking;
+    if (data.wcwidth < 0) {
+        data.width = 0;
+    } else if (data.wcwidth > 2) {
+        data.width = 2;
+    } else {
+        data.width = @intCast(data.wcwidth);
+    }
+}
+
+const width = config.Extension{ .inputs = &.{"wcwidth"}, .compute = &computeWidth, .fields = &.{
+    .{ .name = "width", .type = u2 },
+} };
+
+pub const GraphemeBoundaryClass = enum(u4) {
+    invalid,
+    L,
+    V,
+    T,
+    LV,
+    LVT,
+    prepend,
+    extend,
+    zwj,
+    spacing_mark,
+    regional_indicator,
+    extended_pictographic,
+    extended_pictographic_base, // \p{Extended_Pictographic} & \p{Emoji_Modifier_Base}
+    emoji_modifier, // \p{Emoji_Modifier}
+};
+
+fn computeGraphemeBoundaryClass(cp: u21, data: anytype, backing: anytype, tracking: anytype) void {
+    _ = cp;
+    _ = backing;
+    _ = tracking;
+    if (data.is_emoji_modifier) {
+        data.grapheme_boundary_class = .emoji_modifier;
+    } else if (data.is_emoji_modifier_base) {
+        data.grapheme_boundary_class = .extended_pictographic_base;
+    } else {
+        data.grapheme_boundary_class = switch (data.grapheme_break) {
+            .extended_pictographic => .extended_pictographic,
+            .l => .L,
+            .v => .V,
+            .t => .T,
+            .lv => .LV,
+            .lvt => .LVT,
+            .prepend => .prepend,
+            .zwj => .zwj,
+            .spacing_mark => .spacing_mark,
+            .regional_indicator => .regional_indicator,
+
+            .zwnj,
+            .indic_conjunct_break_extend,
+            .indic_conjunct_break_linker,
+            => .extend,
+
+            // This is obviously not INVALID invalid, there is SOME grapheme
+            // boundary class for every codepoint. But we don't care about
+            // anything that doesn't fit into the above categories.
+            .other,
+            .indic_conjunct_break_consonant,
+            .cr,
+            .lf,
+            .control,
+            => .invalid,
+        };
+    }
+}
+
+const grapheme_boundary_class = config.Extension{
+    .inputs = &.{
+        "grapheme_break",
+        "is_emoji_modifier",
+        "is_emoji_modifier_base",
+    },
+    .compute = &computeGraphemeBoundaryClass,
+    .fields = &.{
+        .{ .name = "grapheme_boundary_class", .type = GraphemeBoundaryClass },
+    },
+};
+
 pub const tables = [_]config.Table{
     .{
         .extensions = &.{wcwidth},
@@ -14,9 +101,16 @@ pub const tables = [_]config.Table{
             d.field("case_folding_full"),
             // Alternative:
             // d.field("case_folding_simple"),
-            d.field("grapheme_break"),
             d.field("is_emoji_modifier"),
             d.field("is_emoji_modifier_base"),
+            d.field("grapheme_break"),
+        },
+    },
+    .{
+        .extensions = &.{ wcwidth, width, grapheme_boundary_class },
+        .fields = &.{
+            width.field("width"),
+            grapheme_boundary_class.field("grapheme_boundary_class"),
         },
     },
 };