url: add ToObject method to native URL class

Provides a factory method to convert a native URL class
into a JS URL object.

```c++
Environment* env = ...

URL url("http://example.org/a/b/c?query#fragment");

MaybeLocal<Value> val = url.ToObject(env);
```

PR-URL: #12056
Reviewed-By: Anna Henningsen <anna@addaleax.net>

lib/internal/bootstrap_node.js

@@ -54,6 +54,10 @@
 
     _process.setupRawDebug();
 
+    // Ensure setURLConstructor() is called before the native
+    // URL::ToObject() method is used.
+    NativeModule.require('internal/url');
+
     Object.defineProperty(process, 'argv0', {
       enumerable: true,
       configurable: false,

lib/internal/url.js

@@ -1400,6 +1400,31 @@ function getPathFromURL(path) {
   return isWindows ? getPathFromURLWin32(path) : getPathFromURLPosix(path);
 }
 
+function NativeURL(ctx) {
+  this[context] = ctx;
+}
+NativeURL.prototype = URL.prototype;
+
+function constructUrl(flags, protocol, username, password,
+                      host, port, path, query, fragment) {
+  var ctx = new URLContext();
+  ctx.flags = flags;
+  ctx.scheme = protocol;
+  ctx.username = username;
+  ctx.password = password;
+  ctx.port = port;
+  ctx.path = path;
+  ctx.query = query;
+  ctx.fragment = fragment;
+  ctx.host = host;
+  const url = new NativeURL(ctx);
+  url[searchParams] = new URLSearchParams();
+  url[searchParams][context] = url;
+  initSearchParams(url[searchParams], query);
+  return url;
+}
+binding.setURLConstructor(constructUrl);
+
 module.exports = {
   toUSVString,
   getPathFromURL,

src/env.h

@@ -273,6 +273,7 @@ namespace node {
   V(tls_wrap_constructor_template, v8::FunctionTemplate)                      \
   V(tty_constructor_template, v8::FunctionTemplate)                           \
   V(udp_constructor_function, v8::Function)                                   \
+  V(url_constructor_function, v8::Function)                                   \
   V(write_wrap_constructor_function, v8::Function)                            \
 
 class Environment;

src/node_url.cc

@@ -27,9 +27,11 @@ using v8::HandleScope;
 using v8::Integer;
 using v8::Isolate;
 using v8::Local;
+using v8::MaybeLocal;
 using v8::Null;
 using v8::Object;
 using v8::String;
+using v8::TryCatch;
 using v8::Undefined;
 using v8::Value;
 
@@ -1226,6 +1228,29 @@ namespace url {
     }
   }
 
+  static inline void SetArgs(Environment* env,
+                             Local<Value> argv[],
+                             const struct url_data* url) {
+    Isolate* isolate = env->isolate();
+    argv[ARG_FLAGS] = Integer::NewFromUnsigned(isolate, url->flags);
+    if (url->flags & URL_FLAGS_HAS_SCHEME)
+      argv[ARG_PROTOCOL] = OneByteString(isolate, url->scheme.c_str());
+    if (url->flags & URL_FLAGS_HAS_USERNAME)
+      argv[ARG_USERNAME] = UTF8STRING(isolate, url->username);
+    if (url->flags & URL_FLAGS_HAS_PASSWORD)
+      argv[ARG_PASSWORD] = UTF8STRING(isolate, url->password);
+    if (url->flags & URL_FLAGS_HAS_HOST)
+      argv[ARG_HOST] = UTF8STRING(isolate, url->host);
+    if (url->flags & URL_FLAGS_HAS_QUERY)
+      argv[ARG_QUERY] = UTF8STRING(isolate, url->query);
+    if (url->flags & URL_FLAGS_HAS_FRAGMENT)
+      argv[ARG_FRAGMENT] = UTF8STRING(isolate, url->fragment);
+    if (url->port > -1)
+      argv[ARG_PORT] = Integer::New(isolate, url->port);
+    if (url->flags & URL_FLAGS_HAS_PATH)
+      argv[ARG_PATH] = Copy(env, url->path);
+  }
+
   static void Parse(Environment* env,
                     Local<Value> recv,
                     const char* input,
@@ -1267,23 +1292,7 @@ namespace url {
         undef,
         undef,
       };
-      argv[ARG_FLAGS] = Integer::NewFromUnsigned(isolate, url.flags);
-      if (url.flags & URL_FLAGS_HAS_SCHEME)
-        argv[ARG_PROTOCOL] = OneByteString(isolate, url.scheme.c_str());
-      if (url.flags & URL_FLAGS_HAS_USERNAME)
-        argv[ARG_USERNAME] = UTF8STRING(isolate, url.username);
-      if (url.flags & URL_FLAGS_HAS_PASSWORD)
-        argv[ARG_PASSWORD] = UTF8STRING(isolate, url.password);
-      if (url.flags & URL_FLAGS_HAS_HOST)
-        argv[ARG_HOST] = UTF8STRING(isolate, url.host);
-      if (url.flags & URL_FLAGS_HAS_QUERY)
-        argv[ARG_QUERY] = UTF8STRING(isolate, url.query);
-      if (url.flags & URL_FLAGS_HAS_FRAGMENT)
-        argv[ARG_FRAGMENT] = UTF8STRING(isolate, url.fragment);
-      if (url.port > -1)
-        argv[ARG_PORT] = Integer::New(isolate, url.port);
-      if (url.flags & URL_FLAGS_HAS_PATH)
-        argv[ARG_PATH] = Copy(env, url.path);
+      SetArgs(env, argv, &url);
       (void)cb->Call(context, recv, arraysize(argv), argv);
     } else if (error_cb->IsFunction()) {
       Local<Value> argv[2] = { undef, undef };
@@ -1418,6 +1427,58 @@ namespace url {
                             v8::NewStringType::kNormal).ToLocalChecked());
   }
 
+  // This function works by calling out to a JS function that creates and
+  // returns the JS URL object. Be mindful of the JS<->Native boundary
+  // crossing that is required.
+  const Local<Value> URL::ToObject(Environment* env) const {
+    Isolate* isolate = env->isolate();
+    Local<Context> context = env->context();
+    HandleScope handle_scope(isolate);
+    Context::Scope context_scope(context);
+
+    const Local<Value> undef = Undefined(isolate);
+
+    if (context_.flags & URL_FLAGS_FAILED)
+      return Local<Value>();
+
+    Local<Value> argv[9] = {
+      undef,
+      undef,
+      undef,
+      undef,
+      undef,
+      undef,
+      undef,
+      undef,
+      undef,
+    };
+    SetArgs(env, argv, &context_);
+
+    TryCatch try_catch(isolate);
+
+    // The SetURLConstructor method must have been called already to
+    // set the constructor function used below. SetURLConstructor is
+    // called automatically when the internal/url.js module is loaded
+    // during the internal/bootstrap_node.js processing.
+    MaybeLocal<Value> ret =
+        env->url_constructor_function()
+            ->Call(env->context(), undef, 9, argv);
+
+    if (ret.IsEmpty()) {
+      ClearFatalExceptionHandlers(env);
+      FatalException(isolate, try_catch);
+    }
+
+    return ret.ToLocalChecked();
+  }
+
+  static void SetURLConstructor(const FunctionCallbackInfo<Value>& args) {
+    Environment* env = Environment::GetCurrent(args);
+    CHECK_EQ(args.Length(), 1);
+    CHECK(args[0]->IsFunction());
+    env->set_url_constructor_function(args[0].As<Function>());
+  }
+
   static void Init(Local<Object> target,
                    Local<Value> unused,
                    Local<Context> context,
@@ -1428,6 +1489,7 @@ namespace url {
     env->SetMethod(target, "toUSVString", ToUSVString);
     env->SetMethod(target, "domainToASCII", DomainToASCII);
     env->SetMethod(target, "domainToUnicode", DomainToUnicode);
+    env->SetMethod(target, "setURLConstructor", SetURLConstructor);
 
 #define XX(name, _) NODE_DEFINE_CONSTANT(target, name);
     FLAGS(XX)

src/node_url.h

@@ -4,11 +4,18 @@
 #if defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS
 
 #include "node.h"
+#include "env.h"
+#include "env-inl.h"
+
 #include <string>
 
 namespace node {
 namespace url {
 
+using v8::Local;
+using v8::Value;
+
+
 #define BIT_AT(a, i)                                                          \
   (!!((unsigned int) (a)[(unsigned int) (i) >> 3] &                           \
   (1 << ((unsigned int) (i) & 7))))
@@ -619,6 +626,8 @@ class URL {
     return ret;
   }
 
+  const Local<Value> ToObject(Environment* env) const;
+
  private:
   struct url_data context_;
 };