feat(zig): native Arboricx bundle parser and C ABI

ext/zig/src/ternary.zig

@@ -0,0 +1,27 @@
+const std = @import("std");
+const tree = @import("tree.zig");
+const Arena = @import("arena.zig").Arena;
+
+pub fn parseTernary(source: []const u8, arena: *Arena) !u32 {
+    var pos: usize = 0;
+    return try parseTernaryRec(source, &pos, arena);
+}
+
+fn parseTernaryRec(source: []const u8, pos: *usize, arena: *Arena) !u32 {
+    if (pos.* >= source.len) return error.UnexpectedEnd;
+    const ch = source[pos.*];
+    pos.* += 1;
+    return switch (ch) {
+        '0' => try arena.alloc(.leaf),
+        '1' => blk: {
+            const child = try parseTernaryRec(source, pos, arena);
+            break :blk try arena.alloc(.{ .stem = .{ .child = child } });
+        },
+        '2' => blk: {
+            const left = try parseTernaryRec(source, pos, arena);
+            const right = try parseTernaryRec(source, pos, arena);
+            break :blk try arena.alloc(.{ .fork = .{ .left = left, .right = right } });
+        },
+        else => error.InvalidChar,
+    };
+}