interface/cpp.cc: cpp_generator::print_method_impl: drop unused variable

[isl.git] / interface / cpp.cc

/*
 * Copyright 2016, 2017 Tobias Grosser. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *    1. Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *
 *    2. Redistributions in binary form must reproduce the above
 *       copyright notice, this list of conditions and the following
 *       disclaimer in the documentation and/or other materials provided
 *       with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY TOBIAS GROSSER ''AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL SVEN VERDOOLAEGE OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
 * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * The views and conclusions contained in the software and documentation
 * are those of the authors and should not be interpreted as
 * representing official policies, either expressed or implied, of
 * Tobias Grosser.
 */

#include <cstdarg>
#include <cstdio>
#include <iostream>
#include <map>
#include <sstream>
#include <string>
#include <vector>

#include "cpp.h"
#include "isl_config.h"

/* Print string formatted according to "fmt" to ostream "os".
 *
 * This osprintf method allows us to use printf style formatting constructs when
 * writing to an ostream.
 */
static void osprintf(ostream &os, const char *format, ...)
{
        va_list arguments;
        char *string_pointer;
        size_t size;

        va_start(arguments, format);
        size = vsnprintf(NULL, 0, format, arguments);
        string_pointer = new char[size + 1];
        va_end(arguments);
        va_start(arguments, format);
        vsnprintf(string_pointer, size + 1, format, arguments);
        va_end(arguments);
        os << string_pointer;
        delete[] string_pointer;
}

/* Convert "l" to a string.
 */
static std::string to_string(long l)
{
        std::ostringstream strm;
        strm << l;
        return strm.str();
}

/* Generate a cpp interface based on the extracted types and functions.
 *
 * Print first a set of forward declarations for all isl wrapper
 * classes, then the declarations of the classes, and at the end all
 * implementations.
 */
void cpp_generator::generate()
{
        ostream &os = cout;

        osprintf(os, "\n");
        osprintf(os, "namespace isl {\n\n");
        osprintf(os, "inline namespace noexceptions {\n\n");

        print_forward_declarations(os);
        osprintf(os, "\n");
        print_declarations(os);
        osprintf(os, "\n");
        print_implementations(os);

        osprintf(os, "} // namespace noexceptions\n");
        osprintf(os, "} // namespace isl\n");
}

/* Print forward declarations for all classes to "os".
*/
void cpp_generator::print_forward_declarations(ostream &os)
{
        map<string, isl_class>::iterator ci;

        osprintf(os, "// forward declarations\n");

        for (ci = classes.begin(); ci != classes.end(); ++ci)
                print_class_forward_decl(os, ci->second);
}

/* Print all declarations to "os".
 */
void cpp_generator::print_declarations(ostream &os)
{
        map<string, isl_class>::iterator ci;
        bool first = true;

        for (ci = classes.begin(); ci != classes.end(); ++ci) {
                if (first)
                        first = false;
                else
                        osprintf(os, "\n");

                print_class(os, ci->second);
        }
}

/* Print all implementations to "os".
 */
void cpp_generator::print_implementations(ostream &os)
{
        map<string, isl_class>::iterator ci;
        bool first = true;

        for (ci = classes.begin(); ci != classes.end(); ++ci) {
                if (first)
                        first = false;
                else
                        osprintf(os, "\n");

                print_class_impl(os, ci->second);
        }
}

/* Print declarations for class "clazz" to "os".
 */
void cpp_generator::print_class(ostream &os, const isl_class &clazz)
{
        const char *name = clazz.name.c_str();
        std::string cppstring = type2cpp(clazz);
        const char *cppname = cppstring.c_str();

        osprintf(os, "// declarations for isl::%s\n", cppname);

        print_class_factory_decl(os, clazz);
        osprintf(os, "\n");
        osprintf(os, "class %s {\n", cppname);
        print_class_factory_decl(os, clazz, "  friend ");
        osprintf(os, "\n");
        osprintf(os, "  %s *ptr = nullptr;\n", name);
        osprintf(os, "\n");
        print_private_constructors_decl(os, clazz);
        osprintf(os, "\n");
        osprintf(os, "public:\n");
        print_public_constructors_decl(os, clazz);
        print_constructors_decl(os, clazz);
        print_copy_assignment_decl(os, clazz);
        print_destructor_decl(os, clazz);
        print_ptr_decl(os, clazz);
        print_get_ctx_decl(os);
        osprintf(os, "\n");
        print_methods_decl(os, clazz);

        osprintf(os, "};\n");
}

/* Print forward declaration of class "clazz" to "os".
 */
void cpp_generator::print_class_forward_decl(ostream &os,
        const isl_class &clazz)
{
        std::string cppstring = type2cpp(clazz);
        const char *cppname = cppstring.c_str();

        osprintf(os, "class %s;\n", cppname);
}

/* Print global factory functions to "os".
 *
 * Each class has two global factory functions:
 *
 *      isl::set manage(__isl_take isl_set *ptr);
 *      isl::set manage_copy(__isl_keep isl_set *ptr);
 *
 * A user can construct isl C++ objects from a raw pointer and indicate whether
 * they intend to take the ownership of the object or not through these global
 * factory functions. This ensures isl object creation is very explicit and
 * pointers are not converted by accident. Thanks to overloading, manage() and
 * manage_copy() can be called on any isl raw pointer and the corresponding
 * object is automatically created, without the user having to choose the right
 * isl object type.
 */
void cpp_generator::print_class_factory_decl(ostream &os,
        const isl_class &clazz, const std::string &prefix)
{
        const char *name = clazz.name.c_str();
        std::string cppstring = type2cpp(clazz);
        const char *cppname = cppstring.c_str();

        os << prefix;
        osprintf(os, "inline isl::%s manage(__isl_take %s *ptr);\n", cppname,
                 name);
        os << prefix;
        osprintf(os, "inline isl::%s manage_copy(__isl_keep %s *ptr);\n",
                cppname, name);
}

/* Print declarations of private constructors for class "clazz" to "os".
 *
 * Each class has currently one private constructor:
 *
 *      1) Constructor from a plain isl_* C pointer
 *
 * Example:
 *
 *      set(__isl_take isl_set *ptr);
 *
 * The raw pointer constructor is kept private. Object creation is only
 * possible through isl::manage() or isl::manage_copy().
 */
void cpp_generator::print_private_constructors_decl(ostream &os,
        const isl_class &clazz)
{
        const char *name = clazz.name.c_str();
        std::string cppstring = type2cpp(clazz);
        const char *cppname = cppstring.c_str();

        osprintf(os, "  inline explicit %s(__isl_take %s *ptr);\n", cppname,
                 name);
}

/* Print declarations of public constructors for class "clazz" to "os".
 *
 * Each class currently has two public constructors:
 *
 *      1) A default constructor
 *      2) A copy constructor
 *
 * Example:
 *
 *      set();
 *      set(const isl::set &set);
 */
void cpp_generator::print_public_constructors_decl(ostream &os,
        const isl_class &clazz)
{
        std::string cppstring = type2cpp(clazz);
        const char *cppname = cppstring.c_str();
        osprintf(os, "  inline /* implicit */ %s();\n", cppname);

        osprintf(os, "  inline /* implicit */ %s(const isl::%s &obj);\n",
                 cppname, cppname);
}

/* Print declarations for constructors for class "class" to "os".
 *
 * For each isl function that is marked as __isl_constructor,
 * add a corresponding C++ constructor.
 *
 * Example:
 *
 *      inline /\* implicit *\/ union_set(isl::basic_set bset);
 *      inline /\* implicit *\/ union_set(isl::set set);
 *      inline explicit val(isl::ctx ctx, long i);
 *      inline explicit val(isl::ctx ctx, const std::string &str);
 */
void cpp_generator::print_constructors_decl(ostream &os,
       const isl_class &clazz)
{
        set<FunctionDecl *>::const_iterator in;
        const set<FunctionDecl *> &constructors = clazz.constructors;

        for (in = constructors.begin(); in != constructors.end(); ++in) {
                FunctionDecl *cons = *in;
                string fullname = cons->getName();
                function_kind kind = function_kind_constructor;

                print_method_decl(os, clazz, fullname, cons, kind);
        }
}

/* Print declarations of copy assignment operator for class "clazz"
 * to "os".
 *
 * Each class has one assignment operator.
 *
 *      isl:set &set::operator=(isl::set obj)
 *
 */
void cpp_generator::print_copy_assignment_decl(ostream &os,
        const isl_class &clazz)
{
        std::string cppstring = type2cpp(clazz);
        const char *cppname = cppstring.c_str();

        osprintf(os, "  inline isl::%s &operator=(isl::%s obj);\n", cppname,
                 cppname);
}

/* Print declaration of destructor for class "clazz" to "os".
 */
void cpp_generator::print_destructor_decl(ostream &os, const isl_class &clazz)
{
        std::string cppstring = type2cpp(clazz);
        const char *cppname = cppstring.c_str();

        osprintf(os, "  inline ~%s();\n", cppname);
}

/* Print declaration of pointer functions for class "clazz" to "os".
 *
 * To obtain a raw pointer three functions are provided:
 *
 *      1) __isl_give isl_set *copy()
 *
 *        Returns a pointer to a _copy_ of the internal object
 *
 *      2) __isl_keep isl_set *get()
 *
 *        Returns a pointer to the internal object
 *
 *      3) __isl_give isl_set *release()
 *
 *        Returns a pointer to the internal object and resets the
 *        internal pointer to nullptr.
 *
 * We also provide functionality to explicitly check if a pointer is
 * currently managed by this object.
 *
 *      4) bool is_null()
 *
 *        Check if the current object is a null pointer.
 *
 * The functions get() and release() model the value_ptr proposed in
 * http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2012/n3339.pdf.
 * The copy() function is an extension to allow the user to explicitly
 * copy the underlying object.
 *
 * Also generate a declaration to delete copy() for r-values, for
 * r-values release() should be used to avoid unnecessary copies.
 */
void cpp_generator::print_ptr_decl(ostream &os, const isl_class &clazz)
{
        const char *name = clazz.name.c_str();

        osprintf(os, "  inline __isl_give %s *copy() const &;\n", name);
        osprintf(os, "  inline __isl_give %s *copy() && = delete;\n", name);
        osprintf(os, "  inline __isl_keep %s *get() const;\n", name);
        osprintf(os, "  inline __isl_give %s *release();\n", name);
        osprintf(os, "  inline bool is_null() const;\n");
}

/* Print the declaration of the get_ctx method.
 */
void cpp_generator::print_get_ctx_decl(ostream &os)
{
        osprintf(os, "  inline isl::ctx get_ctx() const;\n");
}

/* Print declarations for methods in class "clazz" to "os".
 */
void cpp_generator::print_methods_decl(ostream &os, const isl_class &clazz)
{
        map<string, set<FunctionDecl *> >::const_iterator it;

        for (it = clazz.methods.begin(); it != clazz.methods.end(); ++it)
                print_method_group_decl(os, clazz, it->first, it->second);
}

/* Print declarations for methods "methods" of name "fullname" in class "clazz"
 * to "os".
 *
 * "fullname" is the name of the generated C++ method.  It commonly corresponds
 * to the isl name, with the object type prefix dropped.
 * In case of overloaded methods, the result type suffix has also been removed.
 */
void cpp_generator::print_method_group_decl(ostream &os, const isl_class &clazz,
        const string &fullname, const set<FunctionDecl *> &methods)
{
        set<FunctionDecl *>::const_iterator it;

        for (it = methods.begin(); it != methods.end(); ++it) {
                function_kind kind = get_method_kind(clazz, *it);
                print_method_decl(os, clazz, fullname, *it, kind);
        }
}

/* Print declarations for "method" in class "clazz" to "os".
 *
 * "fullname" is the name of the generated C++ method.  It commonly corresponds
 * to the isl name, with the object type prefix dropped.
 * In case of overloaded methods, the result type suffix has also been removed.
 *
 * "kind" specifies the kind of method that should be generated.
 */
void cpp_generator::print_method_decl(ostream &os, const isl_class &clazz,
        const string &fullname, FunctionDecl *method, function_kind kind)
{
        print_method_header(os, clazz, method, fullname, true, kind);
}

/* Print implementations for class "clazz" to "os".
 */
void cpp_generator::print_class_impl(ostream &os, const isl_class &clazz)
{
        std::string cppstring = type2cpp(clazz);
        const char *cppname = cppstring.c_str();

        osprintf(os, "// implementations for isl::%s\n", cppname);

        print_class_factory_impl(os, clazz);
        osprintf(os, "\n");
        print_public_constructors_impl(os, clazz);
        osprintf(os, "\n");
        print_private_constructors_impl(os, clazz);
        osprintf(os, "\n");
        print_constructors_impl(os, clazz);
        osprintf(os, "\n");
        print_copy_assignment_impl(os, clazz);
        osprintf(os, "\n");
        print_destructor_impl(os, clazz);
        osprintf(os, "\n");
        print_ptr_impl(os, clazz);
        osprintf(os, "\n");
        print_get_ctx_impl(os, clazz);
        osprintf(os, "\n");
        print_methods_impl(os, clazz);
}

/* Print implementation of global factory functions to "os".
 */
void cpp_generator::print_class_factory_impl(ostream &os,
        const isl_class &clazz)
{
        const char *name = clazz.name.c_str();
        std::string cppstring = type2cpp(clazz);
        const char *cppname = cppstring.c_str();

        osprintf(os, "isl::%s manage(__isl_take %s *ptr) {\n", cppname, name);
        osprintf(os, "  return %s(ptr);\n", cppname);
        osprintf(os, "}\n");

        osprintf(os, "isl::%s manage_copy(__isl_keep %s *ptr) {\n", cppname,
                name);
        osprintf(os, "  return %s(%s_copy(ptr));\n", cppname, name);
        osprintf(os, "}\n");
}

/* Print implementations of private constructors for class "clazz" to "os".
 */
void cpp_generator::print_private_constructors_impl(ostream &os,
        const isl_class &clazz)
{
        const char *name = clazz.name.c_str();
        std::string cppstring = type2cpp(clazz);
        const char *cppname = cppstring.c_str();

        osprintf(os, "%s::%s(__isl_take %s *ptr)\n    : ptr(ptr) {}\n",
                 cppname, cppname, name);
}

/* Print implementations of public constructors for class "clazz" to "os".
 */
void cpp_generator::print_public_constructors_impl(ostream &os,
        const isl_class &clazz)
{
        std::string cppstring = type2cpp(clazz);
        const char *cppname = cppstring.c_str();

        osprintf(os, "%s::%s()\n    : ptr(nullptr) {}\n\n", cppname, cppname);
        osprintf(os, "%s::%s(const isl::%s &obj)\n    : ptr(obj.copy()) {}\n",
                 cppname, cppname, cppname);
}

/* Print implementations of constructors for class "clazz" to "os".
 */
void cpp_generator::print_constructors_impl(ostream &os,
       const isl_class &clazz)
{
        set<FunctionDecl *>::const_iterator in;
        const set<FunctionDecl *> constructors = clazz.constructors;

        for (in = constructors.begin(); in != constructors.end(); ++in) {
                FunctionDecl *cons = *in;
                string fullname = cons->getName();
                function_kind kind = function_kind_constructor;

                print_method_impl(os, clazz, fullname, cons, kind);
        }
}

/* Print implementation of copy assignment operator for class "clazz" to "os".
 */
void cpp_generator::print_copy_assignment_impl(ostream &os,
        const isl_class &clazz)
{
        const char *name = clazz.name.c_str();
        std::string cppstring = type2cpp(clazz);
        const char *cppname = cppstring.c_str();

        osprintf(os, "%s &%s::operator=(isl::%s obj) {\n", cppname,
                 cppname, cppname);
        osprintf(os, "  std::swap(this->ptr, obj.ptr);\n", name);
        osprintf(os, "  return *this;\n");
        osprintf(os, "}\n");
}

/* Print implementation of destructor for class "clazz" to "os".
 */
void cpp_generator::print_destructor_impl(ostream &os,
        const isl_class &clazz)
{
        const char *name = clazz.name.c_str();
        std::string cppstring = type2cpp(clazz);
        const char *cppname = cppstring.c_str();

        osprintf(os, "%s::~%s() {\n", cppname, cppname);
        osprintf(os, "  if (ptr)\n");
        osprintf(os, "    %s_free(ptr);\n", name);
        osprintf(os, "}\n");
}

/* Print implementation of ptr() functions for class "clazz" to "os".
 */
void cpp_generator::print_ptr_impl(ostream &os, const isl_class &clazz)
{
        const char *name = clazz.name.c_str();
        std::string cppstring = type2cpp(clazz);
        const char *cppname = cppstring.c_str();

        osprintf(os, "__isl_give %s *%s::copy() const & {\n", name, cppname);
        osprintf(os, "  return %s_copy(ptr);\n", name);
        osprintf(os, "}\n\n");
        osprintf(os, "__isl_keep %s *%s::get() const {\n", name, cppname);
        osprintf(os, "  return ptr;\n");
        osprintf(os, "}\n\n");
        osprintf(os, "__isl_give %s *%s::release() {\n", name, cppname);
        osprintf(os, "  %s *tmp = ptr;\n", name);
        osprintf(os, "  ptr = nullptr;\n");
        osprintf(os, "  return tmp;\n");
        osprintf(os, "}\n\n");
        osprintf(os, "bool %s::is_null() const {\n", cppname);
        osprintf(os, "  return ptr == nullptr;\n");
        osprintf(os, "}\n");
}

/* Print the implementation of the get_ctx method.
 */
void cpp_generator::print_get_ctx_impl(ostream &os, const isl_class &clazz)
{
        const char *name = clazz.name.c_str();
        std::string cppstring = type2cpp(clazz);
        const char *cppname = cppstring.c_str();

        osprintf(os, "isl::ctx %s::get_ctx() const {\n", cppname);
        osprintf(os, "  return isl::ctx(%s_get_ctx(ptr));\n", name);
        osprintf(os, "}\n");
}

/* Print definitions for methods of class "clazz" to "os".
 */
void cpp_generator::print_methods_impl(ostream &os, const isl_class &clazz)
{
        map<string, set<FunctionDecl *> >::const_iterator it;
        bool first = true;

        for (it = clazz.methods.begin(); it != clazz.methods.end(); ++it) {
                if (first)
                        first = false;
                else
                        osprintf(os, "\n");
                print_method_group_impl(os, clazz, it->first, it->second);
        }
}

/* Print definitions for methods "methods" of name "fullname" in class "clazz"
 * to "os".
 *
 * "fullname" is the name of the generated C++ method.  It commonly corresponds
 * to the isl name, with the object type prefix dropped.
 * In case of overloaded methods, the result type suffix has also been removed.
 *
 * "kind" specifies the kind of method that should be generated.
 */
void cpp_generator::print_method_group_impl(ostream &os, const isl_class &clazz,
        const string &fullname, const set<FunctionDecl *> &methods)
{
        set<FunctionDecl *>::const_iterator it;
        bool first = true;

        for (it = methods.begin(); it != methods.end(); ++it) {
                function_kind kind;
                if (first)
                        first = false;
                else
                        osprintf(os, "\n");
                kind = get_method_kind(clazz, *it);
                print_method_impl(os, clazz, fullname, *it, kind);
        }
}

/* Print the use of "param" to "os".
 *
 * "load_from_this_ptr" specifies whether the parameter should be loaded from
 * the this-ptr.  In case a value is loaded from a this pointer, the original
 * value must be preserved and must consequently be copied.  Values that are
 * loaded from parameters do not need to be preserved, as such values will
 * already be copies of the actual parameters.  It is consequently possible
 * to directly take the pointer from these values, which saves
 * an unnecessary copy.
 *
 * In case the parameter is a callback function, two parameters get printed,
 * a wrapper for the callback function and a pointer to the actual
 * callback function.  The wrapper is expected to be available
 * in a previously declared variable <name>_lambda, while
 * the actual callback function is expected in <name>_p.
 * The caller of this function must ensure that these variables exist.
 */
void cpp_generator::print_method_param_use(ostream &os, ParmVarDecl *param,
        bool load_from_this_ptr)
{
        string name = param->getName().str();
        const char *name_str = name.c_str();
        QualType type = param->getOriginalType();

        if (type->isIntegerType()) {
                osprintf(os, "%s", name_str);
                return;
        }

        if (is_string(type)) {
                osprintf(os, "%s.c_str()", name_str);
                return;
        }

        if (is_callback(type)) {
                osprintf(os, "%s_lambda, ", name_str);
                osprintf(os, "&%s_p", name_str);
                return;
        }

        if (!load_from_this_ptr && !is_callback(type))
                osprintf(os, "%s.", name_str);

        if (keeps(param)) {
                osprintf(os, "get()");
        } else {
                if (load_from_this_ptr)
                        osprintf(os, "copy()");
                else
                        osprintf(os, "release()");
        }
}

/* Print definition for "method" in class "clazz" to "os".
 *
 * "fullname" is the name of the generated C++ method.  It commonly corresponds
 * to the isl name, with the object type prefix dropped.
 * In case of overloaded methods, the result type suffix has also been removed.
 *
 * "kind" specifies the kind of method that should be generated.
 *
 * This method distinguishes three kinds of methods: member methods, static
 * methods, and constructors.
 *
 * Member methods call "method" by passing to the underlying isl function the
 * isl object belonging to "this" as first argument and the remaining arguments
 * as subsequent arguments. The result of the isl function is returned as a new
 * object if the underlying isl function returns an isl_* ptr or an isl_bool
 * value, as std::string if the isl function returns 'const char *', and as
 * unmodified return value otherwise.
 *
 * Static methods call "method" by passing all arguments to the underlying isl
 * function, as no this-pointer is available. The result is a newly managed
 * isl C++ object.
 *
 * Constructors create a new object from a given set of input parameters. They
 * do not return a value, but instead update the pointer stored inside the
 * newly created object.
 *
 * If the method has a callback argument, we reduce the number of parameters
 * that are exposed by one to hide the user pointer from the interface. On
 * the C++ side no user pointer is needed, as arguments can be forwarded
 * as part of the std::function argument which specifies the callback function.
 */
void cpp_generator::print_method_impl(ostream &os, const isl_class &clazz,
        const string &fullname, FunctionDecl *method, function_kind kind)
{
        string methodname = method->getName();
        int num_params = method->getNumParams();
        QualType return_type = method->getReturnType();
        string rettype_str = type2cpp(return_type);
        bool has_callback = false;

        print_method_header(os, clazz, method, fullname, false, kind);

        for (int i = 0; i < num_params; ++i) {
                ParmVarDecl *param = method->getParamDecl(i);
                if (is_callback(param->getType())) {
                        has_callback = true;
                        num_params -= 1;
                        print_callback_local(os, param);
                }
        }

        osprintf(os, "  auto res = %s(", methodname.c_str());

        for (int i = 0; i < num_params; ++i) {
                ParmVarDecl *param = method->getParamDecl(i);
                bool load_from_this_ptr = false;

                if (i == 0 && kind == function_kind_member_method)
                        load_from_this_ptr = true;

                print_method_param_use(os, param, load_from_this_ptr);

                if (i != num_params - 1)
                        osprintf(os, ", ");
        }
        osprintf(os, ");\n");

        if (kind == function_kind_constructor) {
                osprintf(os, "  ptr = res;\n");
        } else if (is_isl_type(return_type) || is_isl_bool(return_type)) {
                osprintf(os, "  return manage(res);\n");
        } else if (has_callback) {
                osprintf(os, "  return %s(res);\n", rettype_str.c_str());
        } else if (is_string(return_type)) {
                osprintf(os, "  std::string tmp(res);\n");
                if (gives(method))
                        osprintf(os, "  free(res);\n");
                osprintf(os, "  return tmp;\n");
        } else {
                osprintf(os, "  return res;\n");
        }

        osprintf(os, "}\n");
}

/* Print the header for "method" in class "clazz" to "os".
 *
 * Print the header of a declaration if "is_declaration" is set, otherwise print
 * the header of a method definition.
 *
 * "fullname" is the name of the generated C++ method.  It commonly corresponds
 * to the isl name, with the object type prefix dropped.
 * In case of overloaded methods, the result type suffix has also been removed.
 *
 * "kind" specifies the kind of method that should be generated.
 *
 * This function prints headers for member methods, static methods, and
 * constructors, either for their declaration or definition.
 *
 * Member functions are declared as "const", as they do not change the current
 * object, but instead create a new object. They always retrieve the first
 * parameter of the original isl function from the this-pointer of the object,
 * such that only starting at the second parameter the parameters of the
 * original function become part of the method's interface.
 *
 * A function
 *
 *      __isl_give isl_set *isl_set_intersect(__isl_take isl_set *s1,
 *              __isl_take isl_set *s2);
 *
 * is translated into:
 *
 *      inline isl::set intersect(isl::set set2) const;
 *
 * For static functions and constructors all parameters of the original isl
 * function are exposed.
 *
 * Parameters that are defined as __isl_keep or are of type string, are passed
 * as const reference, which allows the compiler to optimize the parameter
 * transfer.
 *
 * Constructors are marked as explicit using the C++ keyword 'explicit' or as
 * implicit using a comment in place of the explicit keyword. By annotating
 * implicit constructors with a comment, users of the interface are made
 * aware of the potential danger that implicit construction is possible
 * for these constructors, whereas without a comment not every user would
 * know that implicit construction is allowed in absence of an explicit keyword.
 */
void cpp_generator::print_method_header(ostream &os, const isl_class &clazz,
        FunctionDecl *method, const string &fullname, bool is_declaration,
        function_kind kind)
{
        string cname = fullname.substr(clazz.name.length() + 1);
        string rettype_str = type2cpp(method->getReturnType());
        string classname = type2cpp(clazz);
        int num_params = method->getNumParams();
        int first_param = 0;

        cname = rename_method(cname);
        if (kind == function_kind_member_method)
                first_param = 1;

        if (is_declaration) {
                osprintf(os, "  ");

                if (kind == function_kind_static_method)
                        osprintf(os, "static ");

                osprintf(os, "inline ");

                if (kind == function_kind_constructor) {
                        if (is_implicit_conversion(clazz, method))
                                osprintf(os, "/* implicit */ ");
                        else
                                osprintf(os, "explicit ");
                }
        }

        if (kind != function_kind_constructor)
                osprintf(os, "%s ", rettype_str.c_str());

        if (!is_declaration)
                osprintf(os, "%s::", classname.c_str());

        if (kind != function_kind_constructor)
                osprintf(os, "%s", cname.c_str());
        else
                osprintf(os, "%s", classname.c_str());

        osprintf(os, "(");

        for (int i = first_param; i < num_params; ++i) {
                ParmVarDecl *param = method->getParamDecl(i);
                QualType type = param->getOriginalType();
                string cpptype = type2cpp(type);

                if (is_callback(type))
                        num_params--;

                if (keeps(param) || is_string(type) || is_callback(type))
                        osprintf(os, "const %s &%s", cpptype.c_str(),
                                 param->getName().str().c_str());
                else
                        osprintf(os, "%s %s", cpptype.c_str(),
                                 param->getName().str().c_str());

                if (i != num_params - 1)
                        osprintf(os, ", ");
        }

        osprintf(os, ")");

        if (kind == function_kind_member_method)
                osprintf(os, " const");

        if (is_declaration)
                osprintf(os, ";\n");
        else
                osprintf(os, " {\n");
}

/* Generate the list of argument types for a callback function of
 * type "type".  If "cpp" is set, then generate the C++ type list, otherwise
 * the C type list.
 *
 * For a callback of type
 *
 *      isl_stat (*)(__isl_take isl_map *map, void *user)
 *
 * the following C++ argument list is generated:
 *
 *      isl::map
 */
string cpp_generator::generate_callback_args(QualType type, bool cpp)
{
        std::string type_str;
        const FunctionProtoType *callback;
        int num_params;

        callback = type->getPointeeType()->getAs<FunctionProtoType>();
        num_params = callback->getNumArgs();
        if (cpp)
                num_params--;

        for (long i = 0; i < num_params; i++) {
                QualType type = callback->getArgType(i);

                if (cpp)
                        type_str += type2cpp(type);
                else
                        type_str += type.getAsString();

                if (!cpp)
                        type_str += "arg_" + ::to_string(i);

                if (i != num_params - 1)
                        type_str += ", ";
        }

        return type_str;
}

/* Generate the full cpp type of a callback function of type "type".
 *
 * For a callback of type
 *
 *      isl_stat (*)(__isl_take isl_map *map, void *user)
 *
 * the following type is generated:
 *
 *      std::function<isl::stat(isl::map)>
 */
string cpp_generator::generate_callback_type(QualType type)
{
        std::string type_str;
        const FunctionProtoType *callback = type->getPointeeType()->getAs<FunctionProtoType>();
        QualType return_type = callback->getReturnType();
        string rettype_str = type2cpp(return_type);

        type_str = "std::function<";
        type_str += rettype_str;
        type_str += "(";
        type_str += generate_callback_args(type, true);
        type_str += ")>";

        return type_str;
}

/* Print the local variables that are needed for a callback argument,
 * in particular, print a lambda function that wraps the callback and
 * a pointer to the actual C++ callback function.
 *
 * For a callback of the form
 *
 *      isl_stat (*fn)(__isl_take isl_map *map, void *user)
 *
 * the following lambda function is generated:
 *
 *      auto fn_lambda = [](isl_map *arg_0, void *arg_1) -> isl_stat {
 *        auto *func = *static_cast<const std::function<stat(map)> **>(arg_1);
 *        stat ret = (*func)(isl::manage(arg_0));
 *        return isl_stat(ret);
 *      };
 *
 * The pointer to the std::function C++ callback function is stored in fn_p.
 * This std::function object represents the actual user
 * callback function together with the locally captured state at the caller.
 *
 * The lambda function is expected to be used as a C callback function
 * where the lambda itself is provided as the function pointer and
 * where the user void pointer is a pointer to fn_p.
 * The std::function object is extracted from the pointer to fn_p
 * inside the lambda function.
 * The double indirection is used to avoid having to worry about
 * const casting.
 */
void cpp_generator::print_callback_local(ostream &os, ParmVarDecl *param)
{
        string pname;
        QualType ptype;
        string call_args, c_args, cpp_args, rettype, last_idx;
        const FunctionProtoType *callback;
        int num_params;

        pname = param->getName().str();
        ptype = param->getType();

        c_args = generate_callback_args(ptype, false);
        cpp_args = generate_callback_type(ptype);

        callback = ptype->getPointeeType()->getAs<FunctionProtoType>();
        rettype = callback->getReturnType().getAsString();
        num_params = callback->getNumArgs();

        last_idx = ::to_string(num_params - 1);

        for (long i = 0; i < num_params - 1; i++) {
                call_args += "isl::manage(arg_" + ::to_string(i) + ")";
                if (i != num_params - 2)
                        call_args += ", ";
        }

        osprintf(os, "  auto %s_p = &%s;\n", pname.c_str(), pname.c_str());
        osprintf(os,
                 "  auto %s_lambda = [](%s) -> %s {\n"
                 "    auto *func = *static_cast<const %s **>(arg_%s);\n"
                 "    stat ret = (*func)(%s);\n"
                 "    return isl_stat(ret);\n"
                 "  };\n",
                 pname.c_str(), c_args.c_str(), rettype.c_str(),
                 cpp_args.c_str(), last_idx.c_str(), call_args.c_str());
}

/* An array listing functions that must be renamed and the function name they
 * should be renamed to. We currently rename functions in case their name would
 * match a reserved C++ keyword, which is not allowed in C++.
 */
static const char *rename_map[][2] = {
        { "union", "unite" },
};

/* Rename method "name" in case the method name in the C++ bindings should not
 * match the name in the C bindings. We do this for example to avoid
 * C++ keywords.
 */
std::string cpp_generator::rename_method(std::string name)
{
        for (size_t i = 0; i < sizeof(rename_map) / sizeof(rename_map[0]); i++)
                if (name.compare(rename_map[i][0]) == 0)
                        return rename_map[i][1];

        return name;
}

/* Translate isl class "clazz" to its corresponding C++ type.
 */
string cpp_generator::type2cpp(const isl_class &clazz)
{
        return type2cpp(clazz.name);
}

/* Translate type string "type_str" to its C++ name counterpart.
*/
string cpp_generator::type2cpp(string type_str)
{
        return type_str.substr(4);
}

/* Translate QualType "type" to its C++ name counterpart.
 */
string cpp_generator::type2cpp(QualType type)
{
        if (is_isl_type(type))
                return "isl::" + type2cpp(type->getPointeeType().getAsString());

        if (is_isl_bool(type))
                return "isl::boolean";

        if (is_isl_stat(type))
                return "isl::stat";

        if (type->isIntegerType())
                return type.getAsString();

        if (is_string(type))
                return "std::string";

        if (is_callback(type))
                return generate_callback_type(type);

        die("Cannot convert type to C++ type");
}

/* Check if "subclass_type" is a subclass of "class_type".
 */
bool cpp_generator::is_subclass(QualType subclass_type,
        const isl_class &class_type)
{
        std::string type_str = subclass_type->getPointeeType().getAsString();
        std::vector<std::string> superclasses;
        std::vector<const isl_class *> parents;
        std::vector<std::string>::iterator ci;

        superclasses = generator::find_superclasses(classes[type_str].type);

        for (ci = superclasses.begin(); ci < superclasses.end(); ci++)
                parents.push_back(&classes[*ci]);

        while (!parents.empty()) {
                const isl_class *candidate = parents.back();

                parents.pop_back();

                if (&class_type == candidate)
                        return true;

                superclasses = generator::find_superclasses(candidate->type);

                for (ci = superclasses.begin(); ci < superclasses.end(); ci++)
                        parents.push_back(&classes[*ci]);
        }

        return false;
}

/* Check if "cons" is an implicit conversion constructor of class "clazz".
 *
 * An implicit conversion constructor is generated in case "cons" has a single
 * parameter, where the parameter type is a subclass of the class that is
 * currently being generated.
 */
bool cpp_generator::is_implicit_conversion(const isl_class &clazz,
        FunctionDecl *cons)
{
        ParmVarDecl *param = cons->getParamDecl(0);
        QualType type = param->getOriginalType();

        int num_params = cons->getNumParams();
        if (num_params != 1)
                return false;

        if (is_isl_type(type) && !is_isl_ctx(type) && is_subclass(type, clazz))
                return true;

        return false;
}

/* Get kind of "method" in "clazz".
 *
 * Given the declaration of a static or member method, returns its kind.
 */
cpp_generator::function_kind cpp_generator::get_method_kind(
        const isl_class &clazz, FunctionDecl *method)
{
        if (is_static(clazz, method))
                return function_kind_static_method;
        else
                return function_kind_member_method;
}