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Unified Diff: dart/sdk/lib/_internal/compiler/implementation/lib/async_patch.dart

Issue 12033003: Deferred (aka lazy) loading of static functions. (Closed) Base URL: https://dart.googlecode.com/svn/branches/bleeding_edge
Patch Set: Rebased Created 7 years, 10 months ago
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Index: dart/sdk/lib/_internal/compiler/implementation/lib/async_patch.dart
diff --git a/dart/sdk/lib/_internal/compiler/implementation/lib/async_patch.dart b/dart/sdk/lib/_internal/compiler/implementation/lib/async_patch.dart
index 0fccce2a432b6eb93bf2af79f0d317545e165f69..8c186458c37ab084c7a22da211e95273b9561649 100644
--- a/dart/sdk/lib/_internal/compiler/implementation/lib/async_patch.dart
+++ b/dart/sdk/lib/_internal/compiler/implementation/lib/async_patch.dart
@@ -5,6 +5,7 @@
// Patch file for the dart:async library.
import 'dart:_isolate_helper' show TimerImpl;
+import 'dart:_foreign_helper' show JS;
patch class Timer {
patch factory Timer(int milliseconds, void callback(Timer timer)) {
@@ -19,3 +20,93 @@ patch class Timer {
return new TimerImpl.repeating(milliseconds, callback);
}
}
+
+// TODO(ahe): This should not only apply to this isolate.
+final _loadedLibraries = <String, Completer<bool>>{};
+
+patch Future<bool> load(String libraryName, {String uri}) {
+ // TODO(ahe): Validate libraryName. Kasper points out that you want
+ // to be able to experiment with the effect of toggling @DeferLoad,
+ // so perhaps we should silently ignore "bad" library names.
+ Completer completer = new Completer<bool>();
+ Future<bool> future = _loadedLibraries[libraryName];
+ if (future != null) {
+ future.then((_) { completer.complete(false); });
+ return completer.future;
+ }
+ _loadedLibraries[libraryName] = completer.future;
+
+ if (uri == null) {
+ uri = _currentScriptUri;
+ int index = JS('int', '#.lastIndexOf("/")', uri);
+ uri = JS('String', '#.substring(0, # + 1) + #', uri, index, "part.js");
+ }
+
+ if (_hasDocument) {
+ // Inject a script tag.
+ var script = JS('', 'document.createElement("script")');
+ JS('', '#.type = "text/javascript"', script);
+ JS('', '#.async = "async"', script);
+ JS('', '#.src = #', script, uri);
+ var onLoad = JS('', '#.bind(null, #)',
+ DART_CLOSURE_TO_JS(_onDeferredLibraryLoad), completer);
+ JS('', '#.addEventListener("load", #, false)', script, onLoad);
+ JS('', 'document.body.appendChild(#)', script);
+ } else if (JS('String', 'typeof load') == 'function') {
+ new Timer(0, (_) {
+ JS('void', 'load(#)', uri);
+ completer.complete(true);
+ });
+ } else {
+ throw new UnsupportedError('load not supported');
+ }
+ return completer.future;
+}
+
+/// Used to implement deferred loading. Used as callback on "load"
+/// event above in [load].
+_onDeferredLibraryLoad(Completer<bool> completer, event) {
+ completer.complete(true);
+}
+
+bool get _hasDocument => JS('String', 'typeof document') == 'object';
+
+/// Returns the URI of the current script (as a string).
+// TODO(ahe): Share with IsolateNatives.computeThisScript.
+String get _currentScriptUri() {
+ // TODO(ahe): The following works in Firefox during loading of the
+ // script, and is being considered for the standard.
+ // if (_hasDocument) {
+ // var currentScript = JS('', 'document.currentScript');
+ // if (JS('String', 'typeof #', currentScript) == 'object') {
+ // return JS('String', '#.src', currentScript);
+ // }
+ // }
+
+ var stack = JS('String|Null', 'new Error().stack');
+ if (stack == null) {
+ // According to Internet Explorer documentation, the stack
+ // property is not set until the exception is thrown.
+ stack = JS('String',
+ 'function() {try{throw new Error()}catch(e){return e.stack}}');
+ }
+ var pattern, matches;
+
+ // This pattern matches V8, Chrome, and Internet Explorer stack
+ // traces that look like this:
+ // Error
+ // at methodName (URI:LINE:COLUMN)
+ pattern = JS('', r'new RegExp("^ *at (.*):[0-9]*:[0-9]*$", "m")');
+
+ matches = JS('', '#.match(#)', stack, pattern);
+ if (matches != null) return matches[1];
+
+ // This pattern matches Firefox stack traces that look like this:
+ // methodName@URI:LINE
+ pattern = JS('', r'new RegExp("^[^@]*@(.*):[0-9]*$", "m")');
+
+ matches = JS('', '#.match(#)', stack, pattern);
+ if (matches != null) return matches[1];
+
+ throw new UnsupportedError('Cannot extract URI from "$stack"');
+}

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