Implement ImportMeta callback

The first time `import.meta` is called within a module, this callback is called
and we can populate it with whatever fields we want. For WebAPI, the important
field is `url`:
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/import.meta

Depends on: lightpanda-io/zig-v8-fork#80

Author: karlseguin

build.zig.zon

@@ -13,8 +13,8 @@
             .hash = "tigerbeetle_io-0.0.0-ViLgxpyRBAB5BMfIcj3KMXfbJzwARs9uSl8aRy2OXULd",
         },
         .v8 = .{
-            .url = "https://github.com/lightpanda-io/zig-v8-fork/archive/23718cdb99aaa45105d0a7e0ca22587bf77d3b5f.tar.gz",
-            .hash = "v8-0.0.0-xddH68m2AwDf42Qp2Udz4wTMVH8p71si7yLlUoZkPeEz",
+            .url = "https://github.com/lightpanda-io/zig-v8-fork/archive/46ddf8c0a2861a4e5717e6f8d0d81a17e42fa0c9.tar.gz",
+            .hash = "v8-0.0.0-xddH6865AwDiDnu-HjMsqm9wXvP9OZOh_4clh_67iQsq",
         },
         //.v8 = .{ .path = "../zig-v8-fork" },
         //.tigerbeetle_io = .{ .path = "../tigerbeetle-io" },

src/browser/page.zig

@@ -1001,7 +1001,11 @@ const Script = struct {
         try_catch.init(page.main_context);
         defer try_catch.deinit();
 
-        const src = self.src orelse page.url.raw;
+        const src: []const u8 = blk: {
+            const s = self.src orelse break :blk page.url.raw;
+            break :blk try URL.stitch(page.arena, s, page.url.raw, .{.alloc = .if_needed});
+        };
+
         // if self.src is null, then this is an inline script, and it should
         // not be cached.
         const cacheable = self.src != null;

src/main.zig

@@ -580,7 +580,7 @@ fn parseCommonArg(
         var it = std.mem.splitScalar(u8, str, ',');
         while (it.next()) |part| {
             try arr.append(allocator, std.meta.stringToEnum(log.Scope, part) orelse {
-                log.fatal(.app, "invalid option choice", .{ .arg = "--log_scope_filter", .value = part });
+                log.fatal(.app, "invalid option choice", .{ .arg = "--log_filter_scopes", .value = part });
                 return false;
             });
         }

src/runtime/js.zig

@@ -197,6 +197,16 @@ pub fn Env(comptime State: type, comptime WebApis: type) type {
             isolate.enter();
             errdefer isolate.exit();
 
+            isolate.setHostInitializeImportMetaObjectCallback(struct {
+                fn callback(c_context: ?*v8.C_Context, c_module: ?*v8.C_Module, c_meta: ?*v8.C_Value) callconv(.C) void {
+                    const v8_context = v8.Context{.handle = c_context.?};
+                    const js_context: *JsContext = @ptrFromInt(v8_context.getEmbedderData(1).castTo(v8.BigInt).getUint64());
+                    js_context.initializeImportMeta(v8.Module{.handle = c_module.?}, v8.Object{.handle = c_meta.?}) catch |err| {
+                        log.err(.js, "import meta", .{ .err = err });
+                    };
+                }
+            }.callback);
+
             var temp_scope: v8.HandleScope = undefined;
             v8.HandleScope.init(&temp_scope, isolate);
             defer temp_scope.deinit();
@@ -726,13 +736,15 @@ pub fn Env(comptime State: type, comptime WebApis: type) type {
 
             fn moduleNoCache(self: *JsContext, src: []const u8, url: []const u8) !void {
                 const m = try compileModule(self.isolate, src, url);
+
+                const arena = self.context_arena;
+                const owned_url = try arena.dupe(u8, url);
+                try self.module_identifier.putNoClobber(arena, m.getIdentityHash(), owned_url);
+
                 const v8_context = self.v8_context;
                 if (try m.instantiate(v8_context, resolveModuleCallback) == false) {
                     return error.ModuleInstantiationError;
                 }
-                const arena = self.context_arena;
-                const owned_url = try arena.dupe(u8, url);
-                try self.module_identifier.putNoClobber(arena, m.getIdentityHash(), owned_url);
                 _ = try m.evaluate(v8_context);
             }
 
@@ -1279,6 +1291,20 @@ pub fn Env(comptime State: type, comptime WebApis: type) type {
                 return self.createException(js_value);
             }
 
+            fn initializeImportMeta(self: *JsContext, m: v8.Module, meta: v8.Object) !void {
+                const url = self.module_identifier.get(m.getIdentityHash()) orelse {
+                    // Shouldn't be possible.
+                    return error.UnknownModuleReferrer;
+                };
+
+                const js_key = v8.String.initUtf8(self.isolate, "url");
+                const js_value = try self.zigValueToJs(url);
+                const res = meta.defineOwnProperty(self.v8_context, js_key.toName(), js_value, 0) orelse false;
+                if (!res) {
+                    return error.FailedToSet;
+                }
+            }
+
             // Callback from V8, asking us to load a module. The "specifier" is
             // the src of the module to load.
             fn resolveModuleCallback(
@@ -1335,7 +1361,7 @@ pub fn Env(comptime State: type, comptime WebApis: type) type {
                 try_catch.init(self);
                 defer try_catch.deinit();
 
-                const m = compileModule(self.isolate, source, specifier) catch |err| {
+                const m = compileModule(self.isolate, source, normalized_specifier) catch |err| {
                     log.warn(.js, "compile resolved module", .{
                         .specifier = specifier,
                         .stack = try_catch.stack(self.call_arena) catch null,

src/url.zig

@@ -111,7 +111,7 @@ pub const URL = struct {
             return src;
         }
 
-        var normalized_src = if (std.mem.startsWith(u8, src, "/")) src[1..] else src;
+        var normalized_src = src;
         while (std.mem.startsWith(u8, normalized_src, "./")) {
             normalized_src = normalized_src[2..];
         }
@@ -131,6 +131,13 @@ pub const URL = struct {
             }
         };
 
+        if (normalized_src[0] == '/') {
+            if (std.mem.indexOfScalarPos(u8, base, protocol_end, '/')) |pos| {
+                return std.fmt.allocPrint(allocator, "{s}{s}", .{ base[0..pos], normalized_src });
+            }
+            // not sure what to do here...error? Just let it fallthrough for now.
+        }
+
         if (std.mem.lastIndexOfScalar(u8, base[protocol_end..], '/')) |index| {
             const last_slash_pos = index + protocol_end;
             if (last_slash_pos == base.len - 1) {
@@ -257,6 +264,16 @@ test "URL: Stitching Base & Src URLs (No Ending Slash)" {
     try testing.expectString("https://lightpanda.io/something.js", result);
 }
 
+test "URL: Stitching Base with absolute src" {
+    const allocator = testing.allocator;
+
+    const base = "https://lightpanda.io/hello";
+    const src = "/abc/something.js";
+    const result = try URL.stitch(allocator, src, base, .{});
+    defer allocator.free(result);
+    try testing.expectString("https://lightpanda.io/abc/something.js", result);
+}
+
 test "URL: Stiching Base & Src URLs (Both Local)" {
     const allocator = testing.allocator;