// 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.

#include "vm/resolver.h"

#include "vm/dart_entry.h"
#include "vm/flags.h"
#include "vm/isolate.h"
#include "vm/log.h"
#include "vm/object.h"
#include "vm/object_store.h"
#include "vm/symbols.h"

namespace dart {

DEFINE_FLAG(bool, trace_resolving, false, "Trace resolving.");

// The actual names of named arguments are not checked by the dynamic resolver,
// but by the method entry code. It is important that the dynamic resolver
// checks that no named arguments are passed to a method that does not accept
// them, since the entry code of such a method does not check for named
// arguments. The dynamic resolver actually checks that a valid number of named
// arguments is passed in.
FunctionPtr Resolver::ResolveDynamic(const Instance& receiver,
                                     const String& function_name,
                                     const ArgumentsDescriptor& args_desc) {
  // Figure out type of receiver first.
  const Class& cls = Class::Handle(receiver.clazz());
  return ResolveDynamicForReceiverClass(cls, function_name, args_desc);
}

FunctionPtr Resolver::ResolveDynamicForReceiverClass(
    const Class& receiver_class,
    const String& function_name,
    const ArgumentsDescriptor& args_desc,
    bool allow_add) {
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();

  Function& function = Function::Handle(
      zone,
      ResolveDynamicAnyArgs(zone, receiver_class, function_name, allow_add));

  if (function.IsNull() || !function.AreValidArguments(args_desc, NULL)) {
    // Return a null function to signal to the upper levels to dispatch to
    // "noSuchMethod" function.
    if (FLAG_trace_resolving) {
      String& error_message =
          String::Handle(zone, Symbols::New(thread, "function not found"));
      if (!function.IsNull()) {
        // Obtain more detailed error message.
        function.AreValidArguments(args_desc, &error_message);
      }
      THR_Print("ResolveDynamic error '%s': %s.\n", function_name.ToCString(),
                error_message.ToCString());
    }
    return Function::null();
  }
  return function.raw();
}

FunctionPtr Resolver::ResolveDynamicAnyArgs(Zone* zone,
                                            const Class& receiver_class,
                                            const String& function_name,
                                            bool allow_add) {
  Class& cls = Class::Handle(zone, receiver_class.raw());
  if (FLAG_trace_resolving) {
    THR_Print("ResolveDynamic '%s' for class %s\n", function_name.ToCString(),
              String::Handle(zone, cls.Name()).ToCString());
  }
  Function& function = Function::Handle(zone);

  String& demangled = String::Handle(zone);

  const bool is_getter = Field::IsGetterName(function_name);
  if (is_getter) {
    demangled = Field::NameFromGetter(function_name);
  }

  if (Function::IsDynamicInvocationForwarderName(function_name)) {
    demangled = Function::DemangleDynamicInvocationForwarderName(function_name);
#ifdef DART_PRECOMPILED_RUNTIME
    // In precompiled mode, the non-dynamic version of the function may be
    // tree-shaken away, so can't necessarily resolve the demanged name.
    while (!cls.IsNull()) {
      function = cls.GetInvocationDispatcher(
          function_name, Array::null_array(),
          FunctionLayout::kDynamicInvocationForwarder,
          /*create_if_absent=*/false);
      if (!function.IsNull()) break;
      cls = cls.SuperClass();
    }
    // Some functions don't require dynamic invocation forwarders, for example
    // if there are no parameters or all the parameters are marked
    // `generic-covariant` (meaning there's no work for the dynamic invocation
    // forwarder to do, see `kernel::DynamicInvocationForwarder`). For these
    // functions, we won't have built a `dyn:` version, but it's safe to just
    // return the original version directly.
    return !function.IsNull() ? function.raw()
                              : ResolveDynamicAnyArgs(zone, receiver_class,
                                                      demangled, allow_add);
#else
    function =
        ResolveDynamicAnyArgs(zone, receiver_class, demangled, allow_add);
    return function.IsNull() ? function.raw()
                             : function.GetDynamicInvocationForwarder(
                                   function_name, allow_add);
#endif
  }

  // Now look for an instance function whose name matches function_name
  // in the class.
  while (!cls.IsNull()) {
    function = cls.LookupDynamicFunction(function_name);
    if (!function.IsNull()) {
      return function.raw();
    }
    // Getter invocation might actually be a method extraction.
    if (is_getter && function.IsNull()) {
      function = cls.LookupDynamicFunction(demangled);
      if (!function.IsNull()) {
        if (allow_add && FLAG_lazy_dispatchers) {
          // We were looking for the getter but found a method with the same
          // name. Create a method extractor and return it.
          // The extractor does not exist yet, so using GetMethodExtractor is
          // not necessary here.
          function = function.CreateMethodExtractor(function_name);
          return function.raw();
        } else {
          return Function::null();
        }
      }
    }
    cls = cls.SuperClass();
  }
  return function.raw();
}

FunctionPtr Resolver::ResolveStatic(const Library& library,
                                    const String& class_name,
                                    const String& function_name,
                                    intptr_t type_args_len,
                                    intptr_t num_arguments,
                                    const Array& argument_names) {
  ASSERT(!library.IsNull());
  Function& function = Function::Handle();
  if (class_name.IsNull() || (class_name.Length() == 0)) {
    // Check if we are referring to a top level function.
    const Object& object = Object::Handle(library.ResolveName(function_name));
    if (!object.IsNull() && object.IsFunction()) {
      function ^= object.raw();
      if (!function.AreValidArguments(type_args_len, num_arguments,
                                      argument_names, NULL)) {
        if (FLAG_trace_resolving) {
          String& error_message = String::Handle();
          // Obtain more detailed error message.
          function.AreValidArguments(type_args_len, num_arguments,
                                     argument_names, &error_message);
          THR_Print("ResolveStatic error '%s': %s.\n",
                    function_name.ToCString(), error_message.ToCString());
        }
        function = Function::null();
      }
    } else {
      if (FLAG_trace_resolving) {
        THR_Print("ResolveStatic error: function '%s' not found.\n",
                  function_name.ToCString());
      }
    }
  } else {
    // Lookup class_name in the library's class dictionary to get at
    // the dart class object. If class_name is not found in the dictionary
    // ResolveStatic will return a NULL function object.
    const Class& cls = Class::Handle(library.LookupClass(class_name));
    if (!cls.IsNull()) {
      function = ResolveStatic(cls, function_name, type_args_len, num_arguments,
                               argument_names);
    }
    if (FLAG_trace_resolving && function.IsNull()) {
      THR_Print("ResolveStatic error: function '%s.%s' not found.\n",
                class_name.ToCString(), function_name.ToCString());
    }
  }
  return function.raw();
}

FunctionPtr Resolver::ResolveStatic(const Class& cls,
                                    const String& function_name,
                                    intptr_t type_args_len,
                                    intptr_t num_arguments,
                                    const Array& argument_names) {
  ASSERT(!cls.IsNull());
  if (FLAG_trace_resolving) {
    THR_Print("ResolveStatic '%s'\n", function_name.ToCString());
  }
  const Function& function =
      Function::Handle(cls.LookupStaticFunction(function_name));
  if (function.IsNull() ||
      !function.AreValidArguments(type_args_len, num_arguments, argument_names,
                                  NULL)) {
    // Return a null function to signal to the upper levels to throw a
    // resolution error or maybe throw the error right here.
    if (FLAG_trace_resolving) {
      String& error_message = String::Handle(String::New("function not found"));
      if (!function.IsNull()) {
        // Obtain more detailed error message.
        function.AreValidArguments(type_args_len, num_arguments, argument_names,
                                   &error_message);
      }
      THR_Print("ResolveStatic error '%s': %s.\n", function_name.ToCString(),
                error_message.ToCString());
    }
    return Function::null();
  }
  return function.raw();
}

}  // namespace dart