Implement automatic loading of dart:core_native_fields library

bin/process_script.cc

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // Handle dart scripts.
 
 #include <stdlib.h>
 #include <string.h>
 #include <stdio.h>
 
 #include "include/dart_api.h"
 
 #include "bin/builtin.h"
+#include "bin/dartutils.h"
 #include "bin/file.h"
 #include "bin/globals.h"
 #include "bin/process_script.h"
 
 static const char* CanonicalizeUrl(const char* reference_dir,
                                    const char* filename) {
   static const char* kDartScheme = "dart:";
   static const intptr_t kDartSchemeLen = strlen(kDartScheme);
   // If the URL starts with "dart:" then it is not modified as it will be
   // handled by the VM internally.
@@ skipping 55 matching lines @@
     return Dart_Error("Unable to fully read contents");
   }
   text_buffer[len] = '\0';
   delete file;
   Dart_Handle str = Dart_NewString(text_buffer);
   free(text_buffer);
   return str;
 }
 
 
-static Dart_Handle LibraryTagHandlerHelper(Dart_LibraryTag tag,
-                                           Dart_Handle library,
-                                           Dart_Handle url,
-                                           bool import_builtin_lib) {
+Dart_Handle LibraryTagHandlerHelper(Dart_LibraryTag tag,
+                                    Dart_Handle library,
+                                    Dart_Handle url,
+                                    bool import_builtin_lib) {
   if (!Dart_IsLibrary(library)) {
     return Dart_Error("not a library");
   }
   if (!Dart_IsString8(url)) {
     return Dart_Error("url is not a string");
   }
   const char* url_chars = NULL;
   Dart_Handle result = Dart_StringToCString(url, &url_chars);
   if (!Dart_IsValid(result)) {
     return Dart_Error("accessing url characters failed");
   }
-
+  bool is_native_flds_library = !strcmp(url_chars,

[Anton Muhin, 2011/11/13 16:19:32]

I am somewhat concerned that logic for dart:core_native_fields resolution belong
to library handler callback.  Now every embedder must remember to implement it
(because technically any loaded lib may do #import(dart:core_native_fields).

May we somehow hide this from embedders?  One option would be to implement this
logic in parser.cc (CallLibraryTagHandler).

Of course, processing of dart:core_native_fields adds some flexibility, but I am
not sure if complexity it adds worths the flexibility we gain.

WDYT?

[siva, 2011/11/15 02:16:52]

Moved this check to just before invoking the library tag handler so that every
embedder does not need to add this check.

On 2011/11/13 16:19:32, antonmuhin wrote:

+                                        DartUtils::kCoreNativeFieldsLibURL);
   if (tag == kCanonicalizeUrl) {
+    if (is_native_flds_library) {
+      return url;
+    }
     // Create the full path based on the including library and the current url.
 
     // Get the url of the calling library.
     Dart_Handle library_url = Dart_LibraryUrl(library);
     if (!Dart_IsValid(library_url)) {
       return Dart_Error("accessing library url failed");
     }
     if (!Dart_IsString8(library_url)) {
       return Dart_Error("library url is not a string");
     }
     const char* library_url_chars = NULL;
     result = Dart_StringToCString(library_url, &library_url_chars);
     if (!Dart_IsValid(result)) {
       return Dart_Error("accessing library url characters failed");
     }
 
     // Calculate the path.
     const char* canon_url_chars = CanonicalizeUrl(library_url_chars, url_chars);
     Dart_Handle canon_url = Dart_NewString(canon_url_chars);
     free(const_cast<char*>(canon_url_chars));
 
     return canon_url;
   }
 
+  if (is_native_flds_library) {
+    return Dart_LookupLibrary(url);
+  }
+
   // The tag is either an import or a source tag. Read the file based on the
   // url chars.
   Dart_Handle source = ReadStringFromFile(url_chars);
   if (!Dart_IsValid(source)) {
     return source;  // source contains the error string.
   }
   if (tag == kImportTag) {
     Dart_Handle new_lib = Dart_LoadLibrary(url, source);
     if (import_builtin_lib && Dart_IsValid(new_lib)) {
       Builtin_ImportLibrary(new_lib);
     }
     return new_lib;  // Return library object or an error string.
   } else if (tag == kSourceTag) {
     return Dart_LoadSource(library, url, source);
   }
   return Dart_Error("wrong tag");
 }
 
+
 static Dart_Handle MainLibraryTagHandler(Dart_LibraryTag tag,
                                          Dart_Handle library,
                                          Dart_Handle url) {
   const bool kImportBuiltinLib = true;  // Import builtin library.
   return LibraryTagHandlerHelper(tag, library, url, kImportBuiltinLib);
 }
 
 
-static Dart_Handle CreateSnapshotLibraryTagHandler(Dart_LibraryTag tag,
-                                                   Dart_Handle library,
-                                                   Dart_Handle url) {
-  const bool kDontImportBuiltinLib = false;  // Do not import builtin lib.
-  return LibraryTagHandlerHelper(tag, library, url, kDontImportBuiltinLib);
-}
-
-
 Dart_Handle LoadScript(const char* script_name) {
   Dart_Handle source = ReadStringFromFile(script_name);
   if (!Dart_IsValid(source)) {
     return source;
   }
   Dart_Handle url = Dart_NewString(script_name);
-
   return Dart_LoadScript(url, source, MainLibraryTagHandler);
 }
 
 
-Dart_Handle LoadSnapshotCreationScript(const char* script_name) {
+Dart_Handle LoadSnapshotCreationScript(const char* script_name,
+                                       Dart_LibraryTagHandler handler) {
   Dart_Handle source = ReadStringFromFile(script_name);
   if (!Dart_IsValid(source)) {
     return source;
   }
   Dart_Handle url = Dart_NewString(script_name);
-
-  return Dart_LoadScript(url, source, CreateSnapshotLibraryTagHandler);
+  return Dart_LoadScript(url, source, handler);
 }