Support Flecs REST API

src/builtin/flecs.rest.zig

@@ -0,0 +1,6 @@
+//! The Flecs REST API enables clients to inspect the contents of the
+//! ECS database, by remotely running queries and requesting entities.
+
+const c = @import("../c.zig");
+
+pub const Rest = c.EcsRest;

src/builtin/flecs.zig

@@ -3,4 +3,5 @@
 pub const core = @import("./flecs.core.zig");
 pub const doc = @import("./flecs.doc.zig");
 pub const pipeline = @import("./flecs.pipeline.zig");
+pub const rest = @import("./flecs.rest.zig");
 pub const system = @import("./flecs.system.zig");

src/world.zig

@@ -49,6 +49,10 @@ pub fn World(comptime ctx: anytype) type {
             flecszigble.allocator.destroy(self);
         }
 
+        pub fn enableRest(self: *Self, options: struct { port: u16 = 0, addr: ?[:0]const u8 = null }) !void {
+            try self.set(flecs.rest.Rest, .{ .port = options.port, .ipaddr = @constCast(options.addr) });
+        }
+
         pub fn progress(self: *Self, delta_time: f32) bool {
             return c.ecs_progress(self.raw, delta_time);
         }
@@ -285,3 +289,32 @@ pub fn World(comptime ctx: anytype) type {
         }
     };
 }
+
+test "World REST API" {
+    const expect = @import("./test/expect.zig");
+    const alloc = std.testing.allocator;
+
+    flecszigble.init(alloc);
+    var world = try World(void).init();
+    defer world.deinit();
+    try world.enableRest(.{ .port = 42666 });
+
+    const Runner = struct {
+        pub fn run(w: *World(void)) void {
+            while (w.progress(0.0)) {}
+        }
+    };
+
+    var thread = try std.Thread.spawn(.{ .allocator = alloc }, Runner.run, .{world});
+    defer thread.join();
+
+    const url = "http://localhost:42666/entity/flecs/core/World";
+    var client = std.http.Client{ .allocator = alloc };
+    defer client.deinit();
+    var result = try client.fetch(alloc, .{ .location = .{ .url = url } });
+    defer result.deinit();
+
+    try expect.equalStrings("{\"path\":\"flecs.core.World\", \"ids\":[]}", result.body);
+
+    world.quit();
+}