Support named arguments for dynamic calls.

frog/leg/emitter.dart

Index: frog/leg/emitter.dart
===================================================================
--- frog/leg/emitter.dart	(revision 3781)
+++ frog/leg/emitter.dart	(working copy)
@@ -41,26 +41,91 @@
                         String prototype,
                         StringBuffer buffer,
                         Invocation invocation) {
-    // TODO(ngeoffray): also support invocation with names.
+    FunctionParameters parameters = member.computeParameters(compiler);
+    int positionalArgumentCount = invocation.positionalArgumentCount;
+    if (positionalArgumentCount == parameters.parameterCount) return;

[floitsch, 2012/02/01 12:19:17]

assert that invocation.namedArgumentCount == 0 before returning?

[ngeoffray, 2012/02/01 13:02:40]

Done.

+    List<SourceString> names = invocation.orderedNamedArguments;
+    assert(names.length == invocation.namedArguments.length);
+
     String invocationName =
-        namer.instanceMethodName(member.name, invocation.argumentCount);
-    int allParameters = member.parameterCount(compiler);
-    int missingParameters = allParameters - invocation.argumentCount;
-    if (missingParameters == 0) return;
-    assert(missingParameters > 0);
+        namer.instanceMethodInvocationName(member.name, invocation);
     buffer.add('$prototype.$invocationName = function(');
-    StringBuffer parameters = new StringBuffer();
-    for (int i = 0; i < invocation.argumentCount; i++) {
-      if (i != 0) parameters.add(', ');
-      parameters.add('param$i');
+
+    // The parameters that this stub takes.
+    StringBuffer parametersBuffer = new StringBuffer();
+    // The missing and named arguments that will be passed to the real
+    // method.
+    StringBuffer missingAndNamedArgumentsBuffer = new StringBuffer();
+    // The positional arguments that will be passed to the real
+    // method.
+    StringBuffer positionalArgumentsBuffer = new StringBuffer();
+
+    // We fullfil the string buffers depending on the selector. For

[floitsch, 2012/02/01 12:19:17]

s/fullfil/fill?

[ngeoffray, 2012/02/01 13:02:40]

Done.

+    // example, take method foo:
+    //    foo(a, b, [c, d]);
+    //
+    // We may have multiple ways of calling foo:
+    // (1) foo(1, 2, 3, 4)
+    // (2) foo(1, 2);
+    // (3) foo(1, 2, c: 3);
+    // (4) foo(1, 2, d: 4);
+    // (5) foo(1, 2, c: 3, d: 4);
+    // (6) foo(1, 2, d: 4, c: 3);
+    //
+    // What we generate at the call sites are:
+    // (1) foo$4(1, 2, 3, 4)
+    // (2) foo$2(1, 2);
+    // (3) foo$3$c(1, 2, c: 3);

[floitsch, 2012/02/01 12:19:17]

remove c:

[ngeoffray, 2012/02/01 13:02:40]

Done.

+    // (4) foo$3$d(1, 2, d: 4);
+    // (5) foo$4$c$d(1, 2, c: 3, d: 4);
+    // (6) foo$4$c$d(1, 2, d: 4, c: 3);

[floitsch, 2012/02/01 12:19:17]

remove d: and c: and reorder 4 and 3.

[ngeoffray, 2012/02/01 13:02:40]

Done.

+    //
+    // The stubs we generate are (expressed in Dart):
+    // (1) No stub generated, call is direct.
+    // (2) foo$2(a, b) => foo$4(a, b, null, null)
+    // (3) foo$3$c(a, b, c) => foo$4(a, b, c, null);
+    // (4) foo$3$d(a, b, d) => foo$4(a, b, null, d);
+    // (5) foo$4$c$d(a, b, c, d) => foo$4(a, b, c, d);
+    // (6) Same as (5).
+    //
+    // We need to generate a stub for (5) because the order of the
+    // stub arguments and the real method may be different.
+
+    int count = 0;
+    parameters.forEachParameter((Element element) {
+      if (count < positionalArgumentCount) {
+        if (count != 0) parametersBuffer.add(', ');

[floitsch, 2012/02/01 12:19:17]

Given these annoyances with the string-buffer, maybe switch to a list<string>
and finish with join(', '). 

[ngeoffray, 2012/02/01 13:02:40]

Done.

+        parametersBuffer.add('${element.name}');

[floitsch, 2012/02/01 12:19:17]

parameter names might need to be mangled (eg. 'with'):
JsNames.getValid(...).
At the same time please add a comment to getValid to make clear that it is an
injection/bijection. Maybe even change the name. Alternatively it would probably
be a good idea to go through to the namer.

[ngeoffray, 2012/02/01 13:02:40]

Done.

+        positionalArgumentsBuffer.add('${element.name}');
+      } else {
+        if (count != positionalArgumentCount || positionalArgumentCount != 0) {
+          missingAndNamedArgumentsBuffer.add(', ');
+        }
+        int index = names.indexOf(element.name);
+        if (index != -1) {
+          // The order of the named arguments is not the same as the
+          // one in the real method (which is in Dart source order).
+          // Therefore, we don't add the argument to the
+          // [parametersBuffer] just yet.
+          missingAndNamedArgumentsBuffer.add('${element.name}');
+        } else {
+          // TODO(ngeoffray): Get the default value.
+          missingAndNamedArgumentsBuffer.add('(void 0)');
+        }
+      }
+      count++;
+    });
+
+    // Add the named arguments to the parametersBuffer.
+    for (SourceString name in names) {
+      if (positionalArgumentCount != 0) parametersBuffer.add(', ');

[floitsch, 2012/02/01 12:19:17]

Only the first name in names should not have a ','.

[ngeoffray, 2012/02/01 13:02:40]

Gone with Strings.join.

+      parametersBuffer.add(name);
     }
-    buffer.add('$parameters) {\n');
-    buffer.add('  this.${namer.getName(member)}($parameters');
-    for (int i = 0; i < missingParameters; i++) {
-      if (i != 0 || invocation.argumentCount != 0) buffer.add(', ');
-      buffer.add('(void 0)');
-    }
-    buffer.add(')\n}\n');
+
+    buffer.add('$parametersBuffer) {\n');
+    buffer.add('  return this.${namer.getName(member)}');
+    buffer.add('($positionalArgumentsBuffer$missingAndNamedArgumentsBuffer)');
+    buffer.add('\n}\n');
   }
 
   void addParameterStubs(FunctionElement member,