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dtool/src/interrogate/functionRemap.cxx

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// Filename: functionRemap.cxx
// Created by:  drose (19Sep01)
//
////////////////////////////////////////////////////////////////////
//
// PANDA 3D SOFTWARE
// Copyright (c) 2001, Disney Enterprises, Inc.  All rights reserved
//
// All use of this software is subject to the terms of the Panda 3d
// Software license.  You should have received a copy of this license
// along with this source code; you will also find a current copy of
// the license at http://www.panda3d.org/license.txt .
//
// To contact the maintainers of this program write to
// panda3d@yahoogroups.com .
//
////////////////////////////////////////////////////////////////////

#include "functionRemap.h"
#include "typeManager.h"
#include "interrogate.h"
#include "parameterRemap.h"
#include "parameterRemapThis.h"
#include "interfaceMaker.h"
#include "interrogateBuilder.h"

#include "interrogateDatabase.h"
#include "cppInstance.h"
#include "cppFunctionType.h"
#include "cppParameterList.h"
#include "cppReferenceType.h"
#include "interrogateType.h"
#include "notify.h"

////////////////////////////////////////////////////////////////////
//     Function: FunctionRemap::Constructor
//       Access: Public
//  Description:
////////////////////////////////////////////////////////////////////
FunctionRemap::
FunctionRemap(const InterrogateType &itype, const InterrogateFunction &ifunc,
              CPPInstance *cppfunc, int num_default_parameters,
              InterfaceMaker *interface) {
  _return_type = (ParameterRemap *)NULL;
  _void_return = true;
  _has_this = false;
  _first_true_parameter = 0;
  _num_default_parameters = num_default_parameters;
  _type = T_normal;
  _wrapper_index = 0;

  _return_value_needs_management = false;
  _return_value_destructor = 0;
  _manage_reference_count = false;

  _cppfunc = cppfunc;
  _ftype = _cppfunc->_type->as_function_type();
  _cpptype = itype._cpptype;
  _cppscope = itype._cppscope;

  _is_valid = setup_properties(ifunc, interface);
}

////////////////////////////////////////////////////////////////////
//     Function: FunctionRemap::Destructor
//       Access: Public
//  Description:
////////////////////////////////////////////////////////////////////
FunctionRemap::
~FunctionRemap() {
}

////////////////////////////////////////////////////////////////////
//     Function: FunctionRemap::get_parameter_name
//       Access: Public
//  Description: Returns a string that will be a suitable name for the
//               nth parameter in the generated code.  This may not
//               correspond to the name of the parameter in the
//               original code.
////////////////////////////////////////////////////////////////////
string FunctionRemap::
get_parameter_name(int n) const {
  ostringstream str;
  str << "param" << n;
  return str.str();
}

////////////////////////////////////////////////////////////////////
//     Function: FunctionRemap::call_function
//       Access: Public
//  Description: Writes a sequence of commands to the given output
//               stream to call the wrapped function.  The parameter
//               values are taken from pexprs, if it is nonempty, or
//               are assumed to be simply the names of the parameters,
//               if it is empty.
//
//               The return value is the expression to return, if we
//               are returning a value, or the empty string if we
//               return nothing.
////////////////////////////////////////////////////////////////////
string FunctionRemap::
call_function(ostream &out, int indent_level, bool convert_result,
              const string &container, const vector_string &pexprs) const {
  string return_expr;

  if (_type == T_destructor) {
    // A destructor wrapper is just a wrapper around the delete operator.
    assert(!container.empty());
    assert(_cpptype != (CPPType *)NULL);

    if (TypeManager::is_reference_count(_cpptype)) {
      // Except for a reference-count type object, in which case the
      // destructor is a wrapper around unref_delete().
      InterfaceMaker::indent(out, indent_level)
        << "unref_delete(" << container << ");\n";
    } else {
      InterfaceMaker::indent(out, indent_level)
        << "delete " << container << ";\n";
    }

  } else if (_type == T_typecast_method) {
    // A typecast method can be invoked implicitly.
    string cast_expr =
      "(" + _return_type->get_orig_type()->get_local_name(&parser) +
      ")(*" + container + ")";

    if (!convert_result) {
      return_expr = cast_expr;
    } else {
      string new_str =
        _return_type->prepare_return_expr(out, indent_level, cast_expr);
      return_expr = _return_type->get_return_expr(new_str);
    }

  } else if (_type == T_typecast) {
    // A regular typecast converts from a pointer type to another
    // pointer type.  (This is different from the typecast method,
    // above, which converts from the concrete type to some other
    // type.)
    assert(!container.empty());
    string cast_expr =
      "(" + _return_type->get_orig_type()->get_local_name(&parser) +
      ")" + container;

    if (!convert_result) {
      return_expr = cast_expr;
    } else {
      string new_str =
        _return_type->prepare_return_expr(out, indent_level, cast_expr);
      return_expr = _return_type->get_return_expr(new_str);
    }

  } else if (_type == T_constructor) {
    // A special case for constructors.
    return_expr = "new " + get_call_str(container, pexprs);
    if (_void_return) {
      nout << "Error, constructor for " << *_cpptype << " returning void.\n";
      return_expr = "";
    }

  } else if (_type == T_assignment_method) {
    // Another special case for assignment operators.
    assert(!container.empty());
    InterfaceMaker::indent(out, indent_level)
      << get_call_str(container, pexprs) << ";\n";

    string this_expr = container;
    string ref_expr = "*" + this_expr;

    if (!convert_result) {
      return_expr = ref_expr;
    } else {
      string new_str =
        _return_type->prepare_return_expr(out, indent_level, ref_expr);
      return_expr = _return_type->get_return_expr(new_str);

      // Now a simple special-case test.  Often, we will have converted
      // the reference-returning assignment operator to a pointer.  In
      // this case, we might inadventent generate code like "return
      // &(*this)", when "return this" would do.  We check for this here
      // and undo it as a special case.

      // There's no real good reason to do this, other than that it
      // feels more satisfying to a casual perusal of the generated
      // code.  It *is* conceivable that some broken compilers wouldn't
      // like "&(*this)", though.

      if (return_expr == "&(" + ref_expr + ")" ||
          return_expr == "&" + ref_expr) {
        return_expr = this_expr;
      }
    }

  } else if (_void_return) {
    InterfaceMaker::indent(out, indent_level)
      << get_call_str(container, pexprs) << ";\n";

  } else {
    string call = get_call_str(container, pexprs);

    if (!convert_result) {
      return_expr = get_call_str(container, pexprs);

    } else {
      if (_return_type->return_value_should_be_simple()) {
        // We have to assign the result to a temporary first; this makes
        // it a bit easier on poor old VC++.
        InterfaceMaker::indent(out, indent_level);
        _return_type->get_orig_type()->output_instance(out, "result",
                                                           &parser);
        out << " = " << call << ";\n";

        string new_str =
          _return_type->prepare_return_expr(out, indent_level, "result");
        return_expr = _return_type->get_return_expr(new_str);

      } else {
        // This should be simple enough that we can return it directly.
        string new_str =
          _return_type->prepare_return_expr(out, indent_level, call);
        return_expr = _return_type->get_return_expr(new_str);
      }
    }
  }

  return return_expr;
}

////////////////////////////////////////////////////////////////////
//     Function: FunctionRemap::write_orig_prototype
//       Access: Public
//  Description: Writes a line describing the original C++ method or
//               function.  This is generally useful only within a
//               comment.
////////////////////////////////////////////////////////////////////
void FunctionRemap::
write_orig_prototype(ostream &out, int indent_level) const {
  _cppfunc->output(out, indent_level, &parser, false, _num_default_parameters);
}

////////////////////////////////////////////////////////////////////
//     Function: FunctionRemap::make_wrapper_entry
//       Access: Public
//  Description: Creates an InterrogateFunctionWrapper object
//               corresponding to this callable instance and stores it
//               in the database.
////////////////////////////////////////////////////////////////////
FunctionWrapperIndex FunctionRemap::
make_wrapper_entry(FunctionIndex function_index) {
  _wrapper_index =
    InterrogateDatabase::get_ptr()->get_next_index();

  InterrogateFunctionWrapper iwrapper;
  iwrapper._function = function_index;
  iwrapper._name = _wrapper_name;
  iwrapper._unique_name = _unique_name;

  if (true_wrapper_names) {
    // If we're reporting "true" names, it means we set the
    // wrapper's name to the name of the function it wraps.
    iwrapper._name = 
      InterrogateBuilder::clean_identifier(_cppfunc->get_local_name(&parser));
  }
  if (output_function_names) {
    // If we're keeping the function names, record that the wrapper is
    // callable.
    iwrapper._flags |= InterrogateFunctionWrapper::F_callable_by_name;
  }

  Parameters::const_iterator pi;
  for (pi = _parameters.begin();
       pi != _parameters.end();
       ++pi) {
    InterrogateFunctionWrapper::Parameter param;
    param._parameter_flags = 0;
    if ((*pi)._remap->new_type_is_atomic_string()) {
      param._type = builder.get_atomic_string_type();
    } else {
      param._type = builder.get_type((*pi)._remap->get_new_type(), false);
    }
    param._name = (*pi)._name;
    if ((*pi)._has_name) {
      param._parameter_flags |= InterrogateFunctionWrapper::PF_has_name;
    }
    iwrapper._parameters.push_back(param);
  }

  if (_has_this) {
    // If one of the parameters is "this", it must be the first one.
    assert(!iwrapper._parameters.empty());
    iwrapper._parameters.front()._parameter_flags |=
      InterrogateFunctionWrapper::PF_is_this;
  }

  if (!_void_return) {
    iwrapper._flags |= InterrogateFunctionWrapper::F_has_return;
  }

  if (_return_type->new_type_is_atomic_string()) {
    iwrapper._return_type = builder.get_atomic_string_type();
  } else {
    iwrapper._return_type =
      builder.get_type(_return_type->get_new_type(), false);
  }

  if (_return_value_needs_management) {
    iwrapper._flags |= InterrogateFunctionWrapper::F_caller_manages;
    FunctionIndex destructor = _return_value_destructor;
    
    if (destructor != 0) {
      iwrapper._return_value_destructor = destructor;
      
    } else {
      // We don't need to report this warning, since the FFI code
      // understands that if the destructor function is zero, it
      // should use the regular class destructor.
      
      //          nout << "Warning!  Destructor for " 
      //               << *_return_type->get_orig_type()
      //               << " is unavailable.\n"
      //               << "  Cannot manage return value for:\n  "
      //               << description << "\n";
    }
  }

  InterrogateDatabase::get_ptr()->add_wrapper(_wrapper_index, iwrapper);
  return _wrapper_index;
}

////////////////////////////////////////////////////////////////////
//     Function: FunctionRemap::get_call_str
//       Access: Private
//  Description: Returns a string suitable for calling the wrapped
//               function.  If pexprs is nonempty, it represents
//               the list of expressions that will evaluate to each
//               parameter value.
////////////////////////////////////////////////////////////////////
string FunctionRemap::
get_call_str(const string &container, const vector_string &pexprs) const {
  // Build up the call to the actual function.
  ostringstream call;

  // Getters and setters are a special case.
  if (_type == T_getter) {
    if (!container.empty()) {
      call << "(" << container << ")->" << _expression;
    } else {
      call << _expression;
    }

  } else if (_type == T_setter) {
    if (!container.empty()) {
      call << "(" << container << ")->" << _expression;
    } else {
      call << _expression;
    }

    call << " = ";
    _parameters[0]._remap->pass_parameter(call, get_parameter_expr(_first_true_parameter, pexprs));

  } else {
    if (_type == T_constructor) {
      // Constructors are called differently.
      call << _cpptype->get_local_name(&parser);

    } else if (_has_this && !container.empty()) {
      // If we have a "this" parameter, the calling convention is also
      // a bit different.
      call << "(" << container << ")->" << _cppfunc->get_local_name();
      
    } else {
      call << _cppfunc->get_local_name(&parser);
    }

    call << "(";
    int pn = _first_true_parameter;
    if (pn < (int)_parameters.size()) {
      _parameters[pn]._remap->pass_parameter(call, get_parameter_expr(pn, pexprs));
      pn++;
      while (pn < (int)_parameters.size()) {
        call << ", ";
        _parameters[pn]._remap->pass_parameter(call, get_parameter_expr(pn, pexprs));
        pn++;
      }
    }
    call << ")";
  }

  return call.str();
}

////////////////////////////////////////////////////////////////////
//     Function: FunctionRemap::get_parameter_expr
//       Access: Private
//  Description: Returns a string that represents the expression
//               associated with the nth parameter.  This is just the
//               nth element of pexprs if it is nonempty, or the name
//               of the nth parameter is it is empty.
////////////////////////////////////////////////////////////////////
string FunctionRemap::
get_parameter_expr(int n, const vector_string &pexprs) const {
  if (n < (int)pexprs.size()) {
    return pexprs[n];
  }
  return get_parameter_name(n);
}

////////////////////////////////////////////////////////////////////
//     Function: FunctionRemap::setup_properties
//       Access: Private
//  Description: Sets up the properties of the function appropriately.
//               Returns true if successful, or false if there is
//               something unacceptable about the function.
////////////////////////////////////////////////////////////////////
bool FunctionRemap::
setup_properties(const InterrogateFunction &ifunc, InterfaceMaker *interface) {
  _function_signature = 
    TypeManager::get_function_signature(_cppfunc, _num_default_parameters);
  _expression = ifunc._expression;

  if ((_ftype->_flags & CPPFunctionType::F_constructor) != 0) {
    _type = T_constructor;

  } else if ((_ftype->_flags & CPPFunctionType::F_destructor) != 0) {
    _type = T_destructor;

  } else if ((_ftype->_flags & CPPFunctionType::F_operator_typecast) != 0) {
    _type = T_typecast_method;

  } else if ((ifunc._flags & InterrogateFunction::F_typecast) != 0) {
    _type = T_typecast;

  } else if ((ifunc._flags & InterrogateFunction::F_getter) != 0) {
    _type = T_getter;

  } else if ((ifunc._flags & InterrogateFunction::F_setter) != 0) {
    _type = T_setter;
  }

  if (_cpptype != (CPPType *)NULL &&
      ((_cppfunc->_storage_class & CPPInstance::SC_static) == 0) &&
      _type != T_constructor) {

    // If this is a method, but not a static method, and not a
    // constructor, then we need a "this" parameter.
    _has_this = true;

    if (interface->synthesize_this_parameter()) {
      // If the interface demands it, the "this" parameter is treated
      // as any other parameter, and inserted at the beginning of the
      // parameter list.
      Parameter param;
      param._name = "this";
      param._has_name = true;
      bool is_const = (_ftype->_flags & CPPFunctionType::F_const_method) != 0;
      param._remap = new ParameterRemapThis(_cpptype, is_const);
      _parameters.push_back(param);
      _first_true_parameter = 1;
    }
      
    // Also check the name of the function.  If it's one of the
    // assignment-style operators, flag it as such.
    string fname = _cppfunc->get_simple_name();
    if (fname == "operator =" ||
        fname == "operator *=" ||
        fname == "operator /=" ||
        fname == "operator %=" ||
        fname == "operator +=" ||
        fname == "operator -=" ||
        fname == "operator |=" ||
        fname == "operator &=" ||
        fname == "operator ^=" ||
        fname == "operator <<=" ||
        fname == "operator >>=") {
      _type = T_assignment_method;
    }
  }

  const CPPParameterList::Parameters &params =
    _ftype->_parameters->_parameters;
  for (int i = 0; i < (int)params.size() - _num_default_parameters; i++) {
    CPPType *type = params[i]->_type->resolve_type(&parser, _cppscope);
    Parameter param;
    param._has_name = true;
    param._name = params[i]->get_simple_name();

    if (param._name.empty()) {
      // If the parameter has no name, record it as being nameless,
      // but also synthesize one in case someone asks anyway.
      param._has_name = false;
      ostringstream param_name;
      param_name << "param" << i;
      param._name = param_name.str();
    }

    param._remap = interface->remap_parameter(_cpptype, type);
    if (param._remap == (ParameterRemap *)NULL) {
      // If we can't handle one of the parameter types, we can't call
      // the function.
      return false;
    }
    param._remap->set_default_value(params[i]->_initializer);

    if (!param._remap->is_valid()) {
      return false;
    }

    _parameters.push_back(param);
  }

  if (_type == T_constructor) {
    // Constructors are a special case.  These appear to return void
    // as seen by the parser, but we know they actually return a new
    // concrete instance.

    if (_cpptype == (CPPType *)NULL) {
      nout << "Method " << *_cppfunc << " has no struct type\n";
      return false;
    }

    _return_type = interface->remap_parameter(_cpptype, _cpptype);
    if (_return_type != (ParameterRemap *)NULL) {
      _void_return = false;
    }

  } else if (_type == T_assignment_method) {
    // Assignment-type methods are also a special case.  We munge
    // these to return *this, which is a semi-standard C++ convention
    // anyway.  We just enforce it.

    if (_cpptype == (CPPType *)NULL) {
      nout << "Method " << *_cppfunc << " has no struct type\n";
      return false;
    } else {
      CPPType *ref_type = CPPType::new_type(new CPPReferenceType(_cpptype));
      _return_type = interface->remap_parameter(_cpptype, ref_type);
      if (_return_type != (ParameterRemap *)NULL) {
        _void_return = false;
      }
    }

  } else {
    // The normal case.
    CPPType *rtype = _ftype->_return_type->resolve_type(&parser, _cppscope);
    _return_type = interface->remap_parameter(_cpptype, rtype);
    if (_return_type != (ParameterRemap *)NULL) {
      _void_return = TypeManager::is_void(rtype);
    }
  }

  if (_return_type == (ParameterRemap *)NULL || 
      !_return_type->is_valid()) {
    // If our return type isn't something we can deal with, treat the
    // function as if it returns NULL.
    _void_return = true;
    CPPType *void_type = TypeManager::get_void_type();
    _return_type = interface->remap_parameter(_cpptype, void_type);
    assert(_return_type != (ParameterRemap *)NULL);
  }
  
  // Do we need to manage the return value?
  _return_value_needs_management = 
    _return_type->return_value_needs_management();
  _return_value_destructor = 
    _return_type->get_return_value_destructor();
  
  // Should we manage a reference count?
  CPPType *return_type = _return_type->get_new_type();
  CPPType *return_meat_type = TypeManager::unwrap_pointer(return_type);
  
  if (manage_reference_counts &&
      TypeManager::is_reference_count_pointer(return_type) &&
      !TypeManager::has_protected_destructor(return_meat_type)) {
    // Yes!
    _manage_reference_count = true;
    _return_value_needs_management = true;
    
    // This is problematic, because we might not have the class in
    // question fully defined here, particularly if the class is
    // defined in some other library.
    _return_value_destructor = builder.get_destructor_for(return_meat_type);
  }

  return true;
}

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