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<font color='#009900'>// Copyright (C) 2017 Davis E. King (davis@dlib.net)
</font><font color='#009900'>// License: Boost Software License See LICENSE.txt for the full license.
</font><font color='#0000FF'>#ifndef</font> DLIB_METApROGRAMMING_Hh_
<font color='#0000FF'>#define</font> DLIB_METApROGRAMMING_Hh_
<font color='#0000FF'>#include</font> "<a style='text-decoration:none' href='algs.h.html'>algs.h</a>"
<font color='#0000FF'>namespace</font> dlib
<b>{</b>
<font color='#009900'>// ----------------------------------------------------------------------------------------
</font>
<font color='#0000FF'>template</font> <font color='#5555FF'><</font><font color='#0000FF'><u>size_t</u></font>... n<font color='#5555FF'>></font>
<font color='#0000FF'>struct</font> <b><a name='compile_time_integer_list'></a>compile_time_integer_list</b>
<b>{</b>
<font color='#009900'>/*!
WHAT THIS OBJECT REPRESENTS
The point of this type is to, as the name suggests, hold a compile time list of integers.
As an example, here is something simple you could do with it:
template <size_t... ints>
void print_compile_time_ints (
compile_time_integer_list<ints...>
)
{
print(ints...);
}
int main()
{
print_compile_time_ints(compile_time_integer_list<0,4,9>());
}
Which just calls: print(0,4,9);
This is a simple example, but this kind of thing is useful in larger and
more complex template metaprogramming constructs.
!*/</font>
<font color='#0000FF'>template</font> <font color='#5555FF'><</font><font color='#0000FF'><u>size_t</u></font> m<font color='#5555FF'>></font>
<font color='#0000FF'>struct</font> <b><a name='push_back'></a>push_back</b>
<b>{</b>
<font color='#0000FF'>typedef</font> compile_time_integer_list<font color='#5555FF'><</font>n..., m<font color='#5555FF'>></font> type;
<b>}</b>;
<b>}</b>;
<font color='#009900'>// ----------------------------------------------------------------------------------------
</font>
<font color='#0000FF'>template</font> <font color='#5555FF'><</font><font color='#0000FF'><u>size_t</u></font> max<font color='#5555FF'>></font>
<font color='#0000FF'>struct</font> <b><a name='make_compile_time_integer_range'></a>make_compile_time_integer_range</b>
<b>{</b>
<font color='#009900'>/*!
WHAT THIS OBJECT REPRESENTS
This object makes a compile_time_integer_list containing the integers in the range [1,max] inclusive.
For example:
make_compile_time_integer_range<4>::type
evaluates to:
compile_time_integer_list<1,2,3,4>
!*/</font>
<font color='#0000FF'>typedef</font> <font color='#0000FF'>typename</font> make_compile_time_integer_range<font color='#5555FF'><</font>max<font color='#5555FF'>-</font><font color='#979000'>1</font><font color='#5555FF'>></font>::type::<font color='#0000FF'>template</font> push_back<font color='#5555FF'><</font>max<font color='#5555FF'>></font>::type type;
<b>}</b>;
<font color='#009900'>// base case
</font> <font color='#0000FF'>template</font> <font color='#5555FF'><</font><font color='#5555FF'>></font> <font color='#0000FF'>struct</font> <b><a name='make_compile_time_integer_range'></a>make_compile_time_integer_range</b><font color='#5555FF'><</font><font color='#979000'>0</font><font color='#5555FF'>></font> <b>{</b> <font color='#0000FF'>typedef</font> compile_time_integer_list<font color='#5555FF'><</font><font color='#5555FF'>></font> type; <b>}</b>;
<font color='#009900'>// ----------------------------------------------------------------------------------------
</font>
<font color='#0000FF'>namespace</font> civ_impl
<b>{</b>
<font color='#0000FF'>template</font> <font color='#5555FF'><</font>
<font color='#0000FF'>typename</font> Funct,
<font color='#0000FF'>typename</font>... Args,
<font color='#0000FF'>typename</font> int_<font color='#5555FF'><</font><b><a name='decltype'></a>decltype</b><font face='Lucida Console'>(</font>std::declval<font color='#5555FF'><</font>Funct<font color='#5555FF'>></font><font face='Lucida Console'>(</font><font face='Lucida Console'>)</font><font face='Lucida Console'>(</font>std::declval<font color='#5555FF'><</font>Args<font color='#5555FF'>></font><font face='Lucida Console'>(</font><font face='Lucida Console'>)</font>...<font face='Lucida Console'>)</font><font face='Lucida Console'>)</font><font color='#5555FF'>></font>::type <font color='#5555FF'>=</font> <font color='#979000'>0</font>
<font color='#5555FF'>></font>
<font color='#0000FF'><u>bool</u></font> <b><a name='call_if_valid'></a>call_if_valid</b> <font face='Lucida Console'>(</font>
special_,
Funct<font color='#5555FF'>&</font><font color='#5555FF'>&</font> f, Args<font color='#5555FF'>&</font><font color='#5555FF'>&</font>... args
<font face='Lucida Console'>)</font>
<b>{</b>
<font color='#BB00BB'>f</font><font face='Lucida Console'>(</font>std::forward<font color='#5555FF'><</font>Args<font color='#5555FF'>></font><font face='Lucida Console'>(</font>args<font face='Lucida Console'>)</font>...<font face='Lucida Console'>)</font>;
<font color='#0000FF'>return</font> <font color='#979000'>true</font>;
<b>}</b>
<font color='#0000FF'>template</font> <font color='#5555FF'><</font>
<font color='#0000FF'>typename</font> Funct,
<font color='#0000FF'>typename</font>... Args
<font color='#5555FF'>></font>
<font color='#0000FF'><u>bool</u></font> <b><a name='call_if_valid'></a>call_if_valid</b> <font face='Lucida Console'>(</font>
general_,
Funct<font color='#5555FF'>&</font><font color='#5555FF'>&</font> <font color='#009900'>/*f*/</font>, Args<font color='#5555FF'>&</font><font color='#5555FF'>&</font>... <font color='#009900'>/*args*/</font>
<font face='Lucida Console'>)</font> <b>{</b> <font color='#0000FF'>return</font> <font color='#979000'>false</font>; <b>}</b>
<b>}</b>
<font color='#0000FF'>template</font> <font color='#5555FF'><</font><font color='#0000FF'>typename</font> Funct, <font color='#0000FF'>typename</font>... Args<font color='#5555FF'>></font>
<font color='#0000FF'><u>bool</u></font> <b><a name='call_if_valid'></a>call_if_valid</b><font face='Lucida Console'>(</font>Funct<font color='#5555FF'>&</font><font color='#5555FF'>&</font> f, Args<font color='#5555FF'>&</font><font color='#5555FF'>&</font>... args<font face='Lucida Console'>)</font>
<font color='#009900'>/*!
ensures
- if f(std::forward<Args>(args)...) is a valid expression then we evaluate it and return
true. Otherwise we do nothing and return false.
!*/</font>
<b>{</b>
<font color='#0000FF'>return</font> civ_impl::<font color='#BB00BB'>call_if_valid</font><font face='Lucida Console'>(</font><font color='#BB00BB'>special_</font><font face='Lucida Console'>(</font><font face='Lucida Console'>)</font>, f, std::forward<font color='#5555FF'><</font>Args<font color='#5555FF'>></font><font face='Lucida Console'>(</font>args<font face='Lucida Console'>)</font>...<font face='Lucida Console'>)</font>;
<b>}</b>
<font color='#009900'>// ----------------------------------------------------------------------------------------
</font>
<b>}</b>
<font color='#0000FF'>#endif</font> <font color='#009900'>// DLIB_METApROGRAMMING_Hh_
</font>
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