hello, Zig! Zig builds the C/C++ code and deps now

The build.sh was obviously bad because it referenced repos on my
computer without any versioning. CMake and Meson don't have any
kind of package management, so would require using submodules.

CMake and Meson are at least as hard to learn as the Zig build
system, but using the Zig build system enables using Zig, which
is a great fit for dropflow since there is so much generated code,
which could be addressed more elegantly with comptime.

Unfortunately the WASM is bigger, but perf-2 speeds up
significantly. I'm probably going to remove the language database
soon, so that will help reduce WASM size again.

Reflection: this took a lot of effort. Zig WASM targets don't
support a memory grow function (ziglang/zig#16429) so most of the
effort was bringing in binaryen and writing a bunch of code to
inject a function call next to memory.grow. Binaryen is needed
anyways for optimizations, but it took a while to get it to build.
I definitely would have been fine with emscripten and submodules
until I needed a reason to use Zig, but oh well, learned a lot.

.gitignore

@@ -1,6 +1,10 @@
 # yarn.
 node_modules/
 
+# zig.
+.zig-cache/
+zig-out/
+
 # dist. track wasm since it changes so infrequently and is complicated to build
 dist/
 !dist/dropflow.wasm

build.zig

@@ -0,0 +1,154 @@
+const std = @import("std");
+
+pub fn build(b: *std.Build) void {
+    const harfbuzz = b.dependency("harfbuzz", .{}).artifact("harfbuzz");
+    const sheenbidi = b.dependency("sheenbidi", .{}).artifact("sheenbidi");
+
+    const dropflow = b.addExecutable(.{
+      .name = "dropflow",
+      .target = b.resolveTargetQuery(.{
+        .cpu_arch = .wasm32,
+        .os_tag = .wasi,
+      }),
+      .optimize = .ReleaseSmall,
+      .single_threaded = true
+    });
+
+    dropflow.addCSourceFiles(.{
+      .files = &.{
+        "src/dropflow.cc",
+        "gen/lang-script-database.cc",
+        "gen/grapheme-break-trie.cc",
+        "gen/line-break-trie.cc",
+        "gen/emoji-trie.cc",
+        "gen/script-trie.cc",
+        "gen/system-fonts-trie.cc",
+        "gen/derived-core-properties-trie.cc",
+        "gen/emoji-scan.c"
+      },
+      .flags = &.{
+        "-fno-exceptions",
+        "-fno-rtti",
+        "-fvisibility-inlines-hidden",
+        "-flto",
+        "-Oz",
+      },
+    });
+
+    dropflow.linkLibrary(harfbuzz);
+    dropflow.linkLibrary(sheenbidi);
+    dropflow.linkLibCpp();
+    dropflow.linkLibC();
+
+    // these are values that emscripten was using. emscripten produced both a
+    // smaller binary and one that required way less memory. copying these
+    // brought the runtime memory down. don't remember if it affected binary size
+    dropflow.global_base = 1024;
+    dropflow.stack_size = 65536;
+    dropflow.initial_memory = 4 * 1024 * 1024;
+    dropflow.entry = .disabled;
+    dropflow.rdynamic = true;
+    dropflow.import_symbols = true;
+    dropflow.export_table = true;
+
+    dropflow.root_module.export_symbol_names = &.{
+      "hb_blob_create",
+      "hb_blob_destroy",
+      "hb_blob_get_data",
+      "hb_blob_get_length",
+      "hb_buffer_add_utf16",
+      "hb_buffer_add_utf8",
+      "hb_buffer_create",
+      "hb_buffer_destroy",
+      "hb_buffer_get_glyph_infos",
+      "hb_buffer_get_glyph_positions",
+      "hb_buffer_get_length",
+      "hb_buffer_set_length",
+      "hb_buffer_guess_segment_properties",
+      "hb_buffer_set_cluster_level",
+      "hb_buffer_set_direction",
+      "hb_buffer_set_flags",
+      "hb_buffer_set_language",
+      "hb_buffer_set_script",
+      "hb_face_create",
+      "hb_face_collect_unicodes",
+      "hb_face_destroy",
+      "hb_face_get_upem",
+      "hb_face_reference_table",
+      "hb_face_count",
+      "hb_font_create",
+      "hb_font_destroy",
+      "hb_font_get_extents_for_direction",
+      "hb_font_glyph_to_string",
+      "hb_font_set_scale",
+      "hb_font_set_variations",
+      "hb_font_get_nominal_glyph",
+      "hb_style_get_value",
+      "hb_ot_name_get_utf16",
+      "hb_glyph_info_get_glyph_flags",
+      "hb_language_from_string",
+      "hb_ot_var_get_axis_infos",
+      "hb_ot_metrics_get_position_with_fallback",
+      "hb_ot_layout_has_substitution",
+      "hb_ot_layout_has_positioning",
+      "hb_ot_layout_table_get_script_tags",
+      "hb_ot_layout_feature_get_lookups",
+      "hb_ot_layout_language_get_feature_indexes",
+      "hb_ot_layout_language_get_feature_tags",
+      "hb_ot_layout_script_get_language_tags",
+      "hb_ot_layout_lookup_collect_glyphs",
+      "hb_ot_layout_language_get_required_feature_index",
+      "hb_script_from_string",
+      "hb_set_create",
+      "hb_set_destroy",
+      "hb_set_get_population",
+      "hb_set_next_many",
+      "hb_set_add",
+      "hb_set_add_range",
+      "hb_set_union",
+      "hb_set_copy",
+      "hb_set_subtract",
+      "hb_set_clear",
+      "hb_set_next",
+      "hb_set_has",
+      "hb_shape",
+      "hbjs_glyph_draw",
+      "SBAlgorithmCreate",
+      "SBAlgorithmRelease",
+      "SBAlgorithmGetParagraphBoundary",
+      "SBAlgorithmCreateParagraph",
+      "SBParagraphRelease",
+      "SBParagraphGetLevelsPtr",
+      "malloc",
+      "free",
+      "free_ptr",
+      // TODO: why isn't __attribute__((used)) for variables working with zig build?
+      // too tired and too close to getting this working to care at the moment
+      "line_break_trie",
+      "emoji_trie",
+      "script_trie",
+      "grapheme_break_trie",
+      "derived_core_properties_trie",
+      "system_font_trie"
+    };
+
+    b.installArtifact(dropflow);
+
+    const binaryen = b.dependency("binaryen", .{});
+
+    const postprocess_wasm = b.addExecutable(.{
+        .name = "postprocess_wasm",
+        .root_source_file = b.path("tools/postprocess_wasm.zig"),
+        .target = b.resolveTargetQuery(.{}),
+        .optimize = .ReleaseFast,
+    });
+
+    postprocess_wasm.linkLibrary(binaryen.artifact("binaryen"));
+
+    const postprocess_wasm_step = b.addRunArtifact(postprocess_wasm);
+    postprocess_wasm_step.addFileArg(dropflow.getEmittedBin());
+    const postprocess_wasm_out = postprocess_wasm_step.addOutputFileArg("dropflow.wasm");
+    const postprocess_wasm_install = b.addInstallFileWithDir(postprocess_wasm_out, .{ .custom = "../dist" }, "dropflow.wasm");
+
+    b.getInstallStep().dependOn(&postprocess_wasm_install.step);
+}

build.zig.zon

@@ -0,0 +1,14 @@
+.{
+    .name = "dropflow",
+    .version = "0.0.0",
+    .paths = .{""},
+    .dependencies = .{
+        .harfbuzz = .{ .path = "./pkg/harfbuzz" },
+        .sheenbidi = .{ .path = "./pkg/sheenbidi" },
+        .binaryen = .{ .path = "./pkg/binaryen" },
+        .tracy = .{
+            .url = "https://github.com/wolfpld/tracy/archive/refs/tags/v0.11.1.tar.gz",
+            .hash = "122022a478dccaed1309fb5d022f4041eec45d40c93a855ed24fad970774c2426d91",
+        },
+    },
+}

gen.js

@@ -294,6 +294,7 @@ static void fill_set(
 `;
 
   for (const [lang] of orths) {
+    c += '__attribute__((visibility("default")))\n';
     c += `__attribute__((used)) hb_set_t* ${lang}_coverage;\n`;
   }