Add a limited version of ParameterMirrors that can only tell whether they are

runtime/vm/dart_api_impl.cc

 // Copyright (c) 2012, 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.
 
 #include "include/dart_api.h"
 
 #include "vm/bigint_operations.h"
 #include "vm/class_finalizer.h"
 #include "vm/compiler.h"
 #include "vm/dart.h"
@@ skipping 2839 matching lines @@
   // to check for a setter function here, but unfortunately the only
   // way to distinguish abstract setter functions is to use the name
   // itself.  Consider adding a RawFunction::kAbstractSetter type.
   const String& func_name = String::Handle(isolate, func.name());
   *is_setter = Field::IsSetterName(func_name);
 
   return Api::Success(isolate);
 }
 
 
+DART_EXPORT Dart_Handle Dart_FunctionParameterCounts(
+    Dart_Handle function,
+    int64_t* fixed_param_count,
+    int64_t* opt_param_count) {
+  Isolate* isolate = Isolate::Current();
+  DARTSCOPE(isolate);
+  if (fixed_param_count == NULL) {
+    RETURN_NULL_ERROR(fixed_param_count);
+  }
+  if (opt_param_count == NULL) {
+    RETURN_NULL_ERROR(opt_param_count);
+  }
+  const Function& func = Api::UnwrapFunctionHandle(isolate, function);
+  if (func.IsNull()) {
+    RETURN_TYPE_ERROR(isolate, function, Function);
+  }
+
+  // We hide implicit parameters, such as a method's receiver. This is
+  // consistent with Invoke or New, which don't expect their callers to
+  // provide them in the argument lists they are handed.
+  *fixed_param_count = (func.num_fixed_parameters() -
+                        func.NumberOfImplicitParameters());
+  *opt_param_count = func.num_optional_parameters();
+
+  return Api::Success(isolate);
+}
+
+
 DART_EXPORT Dart_Handle Dart_GetVariableNames(Dart_Handle target) {
   Isolate* isolate = Isolate::Current();
   DARTSCOPE(isolate);
   const Object& obj = Object::Handle(isolate, Api::UnwrapHandle(target));
   if (obj.IsError()) {
     return target;
   }
 
   const GrowableObjectArray& names =
       GrowableObjectArray::Handle(isolate, GrowableObjectArray::New());
@@ skipping 1250 matching lines @@
     *buffer_size = 0;
   }
 }
 
 
 DART_EXPORT void Dart_InitFlowGraphPrinting(FileWriterFunction function) {
   Dart::set_flow_graph_writer(function);
 }
 
 }  // namespace dart