utilities.hxx

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/************************************************************************/
/*                                                                      */
/*               Copyright 1998-2002 by Ullrich Koethe                  */
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/*    This file is part of the VIGRA computer vision library.           */
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#ifndef VIGRA_BASICS_HXX
#define VIGRA_BASICS_HXX

#include "config.hxx"
#include "error.hxx"
#include "metaprogramming.hxx"
#include "tuple.hxx"
#include "diff2d.hxx"
#include "mathutil.hxx"
#include <string>
#include <sstream>
#include <cctype>
#include <tuple>

/*! \file */

namespace vigra {

/** Convert a value to a string. Available for integral and floating point types
    and void *.
*/
doxygen_overloaded_function(template <class T> std::string asString(T t))

#define VIGRA_AS_STRING(T) \
inline std::string asString(T t) \
{ \
    std::stringstream s; \
    s << t; \
    return s.str(); \
}

VIGRA_AS_STRING(bool)
VIGRA_AS_STRING(signed char)
VIGRA_AS_STRING(unsigned char)
VIGRA_AS_STRING(signed short)
VIGRA_AS_STRING(unsigned short)
VIGRA_AS_STRING(signed long)
VIGRA_AS_STRING(unsigned long)
VIGRA_AS_STRING(signed long long)
VIGRA_AS_STRING(unsigned long long)
VIGRA_AS_STRING(signed int)
VIGRA_AS_STRING(unsigned int)
VIGRA_AS_STRING(float)
VIGRA_AS_STRING(double)
VIGRA_AS_STRING(long double)
VIGRA_AS_STRING(void *)

#undef VIGRA_AS_STRING

template <class T>
std::string operator<<(std::string const & s, T const & t)
{
    std::stringstream ss;
    ss << t;
    return s + ss.str();
}

    /** Convert string to lower case.
    */
inline std::string tolower(std::string s)
{
    for(unsigned int k=0; k<s.size(); ++k)
        s[k] = (std::string::value_type)std::tolower(s[k]);
    return s;
}

inline std::string tolower(const char * s)
{
    return tolower(std::string(s));
}

    /** Convert string to lower case and remove any white space characters.
    */
inline std::string normalizeString(std::string const & s)
{
    std::string res;

    for(unsigned int k=0; k<s.size(); ++k)
    {
        if(std::isspace(s[k]))
            continue;
        res += (std::string::value_type)std::tolower(s[k]);
    }
    return res;
}

inline std::string normalizeString(const char * s)
{
    return normalizeString(std::string(s));
}

namespace detail {

template <class T>
struct FinallyImpl
{
    T & destructor_;

    FinallyImpl(T & destructor)
    : destructor_(destructor)
    {}

    ~FinallyImpl()
    {
        destructor_();
    }
};

} // namespace detail

} // namespace vigra

#define VIGRA_TOKEN_PASTE_IMPL(x, y) x##y
#define VIGRA_TOKEN_PASTE(x, y) VIGRA_TOKEN_PASTE_IMPL(x, y)

#define VIGRA_FINALLY_IMPL(destructor, counter) \
    auto VIGRA_TOKEN_PASTE(_vigra_finally_impl_, counter) = [&]() { destructor; }; \
    ::vigra::detail::FinallyImpl<decltype(VIGRA_TOKEN_PASTE(_vigra_finally_impl_, counter))> \
        VIGRA_TOKEN_PASTE(_vigra_finally_, counter)(VIGRA_TOKEN_PASTE(_vigra_finally_impl_, counter))

    /** Emulate the 'finally' keyword as known from Python and other languages.

        This macro improves upon the famous
        <a href="http://en.wikipedia.org/wiki/Resource_Acquisition_Is_Initialization">Resource Acquisition Is Initialization</a> idiom, where a resource (e.g. heap memory or a mutex) is automatically free'ed when program execution leaves the current scope. This is normally achieved by placing a call which  releases the resource into the destructor of a dedicated helper class (e.g. <tt>std::unique_ptr</tt> or <tt>std::lock_guard<std::mutex></tt>).

        Traditionally, a separate helper class is needed for every type of resource to be handled. In contrast, the macro <tt>VIGRA_FINALLY</tt> creates such a class on the fly by means of an embedded lambda expression.

        <b>Usage:</b>

        <b>\#include</b> <vigra/utilities.hxx><br/>

        \code
        std::mutex my_mutex;
        ...
        {
            // the following two lines are equivalent to
            //     std::unique_ptr<std::string> my_string = new std::string("foo");
            std::string * my_string = new std::string("foo");
            VIGRA_FINALLY(delete my_string);

            // the following two lines are equivalent to
            //     std::lock_guard<std::mutex> lock(my_mutex);
            my_mutex.lock();
            VIGRA_FINALLY(my_mutex.unlock());

            ...
        }
        // the string has been deallocated and the mutex is unlocked
        \endcode

        You can pass any code to this macro. Multiple statements must be enclosed in braces as usual. Arbitrary many calls to <tt>VIGRA_FINALLY</tt> can be placed in the same scope. Their actions will be executed in the reversed order of declaration:

        \code
        int i = 0;
        ...
        {
            VIGRA_FINALLY({           // execute multiple statements
                i = i*i;
                ++i;
            });

            VIGRA_FINALLY( i += 2 );  // this executes first

            assert(i == 0);           // as yet, nothing happend
        }
        assert(i == 5);               // 'finally' code was executed in reversed order at end-of-scope
        \endcode

        This idea was popularized by Marko Tintor in <a href="http://blog.memsql.com/c-error-handling-with-auto/">The Auto Macro: A Clean Approach to C++ Error Handling</a>.
    */
#define VIGRA_FINALLY(destructor) \
    VIGRA_FINALLY_IMPL(destructor, __COUNTER__)

namespace std {

template <class T1, class T2>
ostream & operator<<(ostream & s, std::pair<T1, T2> const & p)
{
    s << "(" << p.first << ", " << p.second << ")";
    return s;
}

}

namespace vigra
{
namespace detail
{
    template <typename TPL, size_t N, typename FUNCTOR>
    struct for_each_in_tuple_impl
    {
        typedef for_each_in_tuple_impl<TPL, N-1, FUNCTOR> ForEachRecursion;
        
        void operator()(TPL && t, FUNCTOR && f) const
        {
            ForEachRecursion()(std::forward<TPL>(t), std::forward<FUNCTOR>(f));
            f(std::get<N-1>(std::forward<TPL>(t)));
        }
    };
    
    template <typename TPL, typename FUNCTOR>
    struct for_each_in_tuple_impl<TPL, 0, FUNCTOR>
    {
        void operator()(TPL && t, FUNCTOR && f) const
        {}
    };
} // namespace detail

/**
 * The for_each_in_tuple function calls the functor f on all elements of the tuple t.
 * For each element type in the tuple, the functor must have an appropriate overload of operator().
 * 
 * Example:
 * \code
 * #include <iostream>
 * #include <tuple>
 * #include <vigra/utilities.hxx>
 * 
 * struct print
 * {
 *     template <typename T>
 *     void operator()(T const & t) const
 *     {
 *         std::cout << t << std::endl;
 *     }
 * };
 * 
 * struct add_one
 * {
 *     template <typename T>
 *     void operator()(T & t) const
 *     {
 *         t += 1;
 *     }
 * };
 * 
 * int main()
 * {
 *     std::tuple<int, double, size_t> tpl(-5, 0.4, 10);
 *     vigra::for_each_in_tuple(tpl, add_one());
 *     vigra::for_each_in_tuple(tpl, print());
 * }
 * \endcode
 */
template <typename TPL, typename FUNCTOR>
void for_each_in_tuple(TPL && t, FUNCTOR && f)
{
    typedef typename std::decay<TPL>::type UNQUALIFIED_TPL;
    typedef detail::for_each_in_tuple_impl<TPL, std::tuple_size<UNQUALIFIED_TPL>::value, FUNCTOR> ForEachImpl;
    
    ForEachImpl()(std::forward<TPL>(t), std::forward<FUNCTOR>(f));
}

} // namespace vigra

/** \page Utilities Utilities
    Basic helper functionality needed throughout.

    <UL style="list-style-image:url(documents/bullet.gif)">
    <LI> \ref vigra::ArrayVector
         <BR>&nbsp;&nbsp;&nbsp;<em>replacement for std::vector (always uses consecutive memory)</em>
    <LI> \ref vigra::Any
         <BR>&nbsp;&nbsp;&nbsp;<em>typesafe storage of arbitrary values</em>
    <LI> \ref vigra::BucketQueue and \ref vigra::MappedBucketQueue
         <BR>&nbsp;&nbsp;&nbsp;<em>efficient priority queues for integer priorities</em>
    <LI> \ref RangesAndPoints
         <BR>&nbsp;&nbsp;&nbsp;<em>2-D and N-D positions, extents, and boxes</em>
    <LI> \ref PixelNeighborhood
         <BR>&nbsp;&nbsp;&nbsp;<em>4- and 8-neighborhood definitions and circulators</em>
    <LI> \ref VoxelNeighborhood
         <BR>&nbsp;&nbsp;&nbsp;<em>6- and 26-neighborhood definitions and circulators</em>
    <LI> \ref vigra::IteratorAdaptor
         <BR>&nbsp;&nbsp;&nbsp;<em>Quickly create STL-compatible 1D iterator adaptors</em>
    <LI> \ref TupleTypes
         <BR>&nbsp;&nbsp;&nbsp;<em>pair, triple, tuple4, tuple5</em>
    <LI> \ref MathConstants
         <BR>&nbsp;&nbsp;&nbsp;<em>M_PI, M_SQRT2</em>
    <LI> \ref TimingMacros
         <BR>&nbsp;&nbsp;&nbsp;<em>Macros for taking execution speed measurements</em>
    <LI> \ref VIGRA_FINALLY
         <BR>&nbsp;&nbsp;&nbsp;<em>Emulation of the 'finally' keyword from Python</em>
    </UL>
*/

#endif // VIGRA_BASICS_HXX