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| author | johannst <johannst@users.noreply.github.com> | 2022-08-23 19:48:10 +0000 |
|---|---|---|
| committer | johannst <johannst@users.noreply.github.com> | 2022-08-23 19:48:10 +0000 |
| commit | 25b609d0c70d49dd62479ce03578704e62712bd8 (patch) | |
| tree | f9c761f5c72ded4cf9c31bad9f15109cf810b55c /development/c++.html | |
| parent | f647a8c45dda58078c86a96c68ae00ea1c69a222 (diff) | |
| download | notes-25b609d0c70d49dd62479ce03578704e62712bd8.tar.gz notes-25b609d0c70d49dd62479ce03578704e62712bd8.zip | |
deploy: 6f6fef7bb61712038220a7607447d38689ad6978
Diffstat (limited to 'development/c++.html')
| -rw-r--r-- | development/c++.html | 249 |
1 files changed, 159 insertions, 90 deletions
diff --git a/development/c++.html b/development/c++.html index a478e7b..2ae657c 100644 --- a/development/c++.html +++ b/development/c++.html @@ -4,39 +4,33 @@ <!-- Book generated using mdBook --> <meta charset="UTF-8"> <title>c++ - Notes</title> - - + <!-- Custom HTML head --> <meta content="text/html; charset=utf-8" http-equiv="Content-Type"> <meta name="description" content=""> <meta name="viewport" content="width=device-width, initial-scale=1"> <meta name="theme-color" content="#ffffff" /> + <link rel="icon" href="../favicon.svg"> <link rel="shortcut icon" href="../favicon.png"> <link rel="stylesheet" href="../css/variables.css"> <link rel="stylesheet" href="../css/general.css"> <link rel="stylesheet" href="../css/chrome.css"> <link rel="stylesheet" href="../css/print.css" media="print"> - <!-- Fonts --> <link rel="stylesheet" href="../FontAwesome/css/font-awesome.css"> - <link href="https://fonts.googleapis.com/css?family=Open+Sans:300italic,400italic,600italic,700italic,800italic,400,300,600,700,800" rel="stylesheet" type="text/css"> - <link href="https://fonts.googleapis.com/css?family=Source+Code+Pro:500" rel="stylesheet" type="text/css"> - + <link rel="stylesheet" href="../fonts/fonts.css"> <!-- Highlight.js Stylesheets --> <link rel="stylesheet" href="../highlight.css"> <link rel="stylesheet" href="../tomorrow-night.css"> <link rel="stylesheet" href="../ayu-highlight.css"> <!-- Custom theme stylesheets --> - - - </head> <body> <!-- Provide site root to javascript --> <script type="text/javascript"> var path_to_root = "../"; - var default_theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? "light" : "light"; + var default_theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? "navy" : "light"; </script> <!-- Work around some values being stored in localStorage wrapped in quotes --> @@ -80,8 +74,8 @@ </script> <nav id="sidebar" class="sidebar" aria-label="Table of contents"> - <div id="sidebar-scrollbox" class="sidebar-scrollbox"> - <ol class="chapter"><li class="expanded affix "><a href="../intro.html">Introduction</a></li><li class="expanded "><a href="../tools/index.html"><strong aria-hidden="true">1.</strong> Tools</a></li><li><ol class="section"><li class="expanded "><a href="../tools/zsh.html"><strong aria-hidden="true">1.1.</strong> zsh</a></li><li class="expanded "><a href="../tools/bash.html"><strong aria-hidden="true">1.2.</strong> bash</a></li><li class="expanded "><a href="../tools/fish.html"><strong aria-hidden="true">1.3.</strong> fish</a></li><li class="expanded "><a href="../tools/tmux.html"><strong aria-hidden="true">1.4.</strong> tmux</a></li><li class="expanded "><a href="../tools/git.html"><strong aria-hidden="true">1.5.</strong> git</a></li><li class="expanded "><a href="../tools/awk.html"><strong aria-hidden="true">1.6.</strong> awk</a></li><li class="expanded "><a href="../tools/emacs.html"><strong aria-hidden="true">1.7.</strong> emacs</a></li><li class="expanded "><a href="../tools/gpg.html"><strong aria-hidden="true">1.8.</strong> gpg</a></li><li class="expanded "><a href="../tools/gdb.html"><strong aria-hidden="true">1.9.</strong> gdb</a></li><li class="expanded "><a href="../tools/gdbserver.html"><strong aria-hidden="true">1.10.</strong> gdbserver</a></li><li class="expanded "><a href="../tools/radare2.html"><strong aria-hidden="true">1.11.</strong> radare2</a></li><li class="expanded "><a href="../tools/qemu.html"><strong aria-hidden="true">1.12.</strong> qemu</a></li><li class="expanded "><a href="../tools/pacman.html"><strong aria-hidden="true">1.13.</strong> pacman</a></li><li class="expanded "><a href="../tools/dot.html"><strong aria-hidden="true">1.14.</strong> dot</a></li></ol></li><li class="expanded "><a href="../monitor/index.html"><strong aria-hidden="true">2.</strong> Resource analysis & monitor</a></li><li><ol class="section"><li class="expanded "><a href="../monitor/lsof.html"><strong aria-hidden="true">2.1.</strong> lsof</a></li><li class="expanded "><a href="../monitor/ss.html"><strong aria-hidden="true">2.2.</strong> ss</a></li><li class="expanded "><a href="../monitor/pidstat.html"><strong aria-hidden="true">2.3.</strong> pidstat</a></li><li class="expanded "><a href="../monitor/pgrep.html"><strong aria-hidden="true">2.4.</strong> pgrep</a></li><li class="expanded "><a href="../monitor/pmap.html"><strong aria-hidden="true">2.5.</strong> pmap</a></li><li class="expanded "><a href="../monitor/pstack.html"><strong aria-hidden="true">2.6.</strong> pstack</a></li></ol></li><li class="expanded "><a href="../trace_profile/index.html"><strong aria-hidden="true">3.</strong> Trace and Profile</a></li><li><ol class="section"><li class="expanded "><a href="../trace_profile/strace.html"><strong aria-hidden="true">3.1.</strong> strace</a></li><li class="expanded "><a href="../trace_profile/ltrace.html"><strong aria-hidden="true">3.2.</strong> ltrace</a></li><li class="expanded "><a href="../trace_profile/perf.html"><strong aria-hidden="true">3.3.</strong> perf</a></li><li class="expanded "><a href="../trace_profile/oprofile.html"><strong aria-hidden="true">3.4.</strong> OProfile</a></li><li class="expanded "><a href="../trace_profile/time.html"><strong aria-hidden="true">3.5.</strong> time</a></li></ol></li><li class="expanded "><a href="../binary/index.html"><strong aria-hidden="true">4.</strong> Binary</a></li><li><ol class="section"><li class="expanded "><a href="../binary/od.html"><strong aria-hidden="true">4.1.</strong> od</a></li><li class="expanded "><a href="../binary/xxd.html"><strong aria-hidden="true">4.2.</strong> xxd</a></li><li class="expanded "><a href="../binary/readelf.html"><strong aria-hidden="true">4.3.</strong> readelf</a></li><li class="expanded "><a href="../binary/objdump.html"><strong aria-hidden="true">4.4.</strong> objdump</a></li><li class="expanded "><a href="../binary/nm.html"><strong aria-hidden="true">4.5.</strong> nm</a></li></ol></li><li class="expanded "><a href="../development/index.html"><strong aria-hidden="true">5.</strong> Development</a></li><li><ol class="section"><li class="expanded "><a href="../development/c++filt.html"><strong aria-hidden="true">5.1.</strong> c++filt</a></li><li class="expanded "><a href="../development/c++.html" class="active"><strong aria-hidden="true">5.2.</strong> c++</a></li><li class="expanded "><a href="../development/glibc.html"><strong aria-hidden="true">5.3.</strong> glibc</a></li><li class="expanded "><a href="../development/gcc.html"><strong aria-hidden="true">5.4.</strong> gcc</a></li><li class="expanded "><a href="../development/make.html"><strong aria-hidden="true">5.5.</strong> make</a></li><li class="expanded "><a href="../development/ld.so.html"><strong aria-hidden="true">5.6.</strong> ld.so</a></li><li class="expanded "><a href="../development/symbolver.html"><strong aria-hidden="true">5.7.</strong> symbol versioning</a></li><li class="expanded "><a href="../development/python.html"><strong aria-hidden="true">5.8.</strong> python</a></li></ol></li><li class="expanded "><a href="../linux/index.html"><strong aria-hidden="true">6.</strong> Linux</a></li><li><ol class="section"><li class="expanded "><a href="../linux/systemd.html"><strong aria-hidden="true">6.1.</strong> systemd</a></li><li class="expanded "><a href="../linux/coredump.html"><strong aria-hidden="true">6.2.</strong> coredump</a></li><li class="expanded "><a href="../linux/ptrace_scope.html"><strong aria-hidden="true">6.3.</strong> ptrace_scope</a></li></ol></li><li class="expanded "><a href="../network/index.html"><strong aria-hidden="true">7.</strong> Network</a></li><li><ol class="section"><li class="expanded "><a href="../network/tcpdump.html"><strong aria-hidden="true">7.1.</strong> tcpdump</a></li></ol></li><li class="expanded "><a href="../arch/index.html"><strong aria-hidden="true">8.</strong> Arch</a></li><li><ol class="section"><li class="expanded "><a href="../arch/x86_64.html"><strong aria-hidden="true">8.1.</strong> x86_64</a></li><li class="expanded "><a href="../arch/arm64.html"><strong aria-hidden="true">8.2.</strong> arm64</a></li><li class="expanded "><a href="../arch/armv7.html"><strong aria-hidden="true">8.3.</strong> armv7</a></li><li class="expanded "><a href="../arch/riscv.html"><strong aria-hidden="true">8.4.</strong> riscv</a></li></ol></li></ol> + <div class="sidebar-scrollbox"> + <ol class="chapter"><li class="chapter-item expanded affix "><a href="../intro.html">Introduction</a></li><li class="chapter-item expanded "><a href="../tools/index.html"><strong aria-hidden="true">1.</strong> Tools</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../tools/zsh.html"><strong aria-hidden="true">1.1.</strong> zsh</a></li><li class="chapter-item expanded "><a href="../tools/bash.html"><strong aria-hidden="true">1.2.</strong> bash</a></li><li class="chapter-item expanded "><a href="../tools/fish.html"><strong aria-hidden="true">1.3.</strong> fish</a></li><li class="chapter-item expanded "><a href="../tools/tmux.html"><strong aria-hidden="true">1.4.</strong> tmux</a></li><li class="chapter-item expanded "><a href="../tools/git.html"><strong aria-hidden="true">1.5.</strong> git</a></li><li class="chapter-item expanded "><a href="../tools/awk.html"><strong aria-hidden="true">1.6.</strong> awk</a></li><li class="chapter-item expanded "><a href="../tools/emacs.html"><strong aria-hidden="true">1.7.</strong> emacs</a></li><li class="chapter-item expanded "><a href="../tools/gpg.html"><strong aria-hidden="true">1.8.</strong> gpg</a></li><li class="chapter-item expanded "><a href="../tools/gdb.html"><strong aria-hidden="true">1.9.</strong> gdb</a></li><li class="chapter-item expanded "><a href="../tools/gdbserver.html"><strong aria-hidden="true">1.10.</strong> gdbserver</a></li><li class="chapter-item expanded "><a href="../tools/radare2.html"><strong aria-hidden="true">1.11.</strong> radare2</a></li><li class="chapter-item expanded "><a href="../tools/qemu.html"><strong aria-hidden="true">1.12.</strong> qemu</a></li><li class="chapter-item expanded "><a href="../tools/pacman.html"><strong aria-hidden="true">1.13.</strong> pacman</a></li><li class="chapter-item expanded "><a href="../tools/dot.html"><strong aria-hidden="true">1.14.</strong> dot</a></li></ol></li><li class="chapter-item expanded "><a href="../monitor/index.html"><strong aria-hidden="true">2.</strong> Resource analysis & monitor</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../monitor/lsof.html"><strong aria-hidden="true">2.1.</strong> lsof</a></li><li class="chapter-item expanded "><a href="../monitor/ss.html"><strong aria-hidden="true">2.2.</strong> ss</a></li><li class="chapter-item expanded "><a href="../monitor/pidstat.html"><strong aria-hidden="true">2.3.</strong> pidstat</a></li><li class="chapter-item expanded "><a href="../monitor/pgrep.html"><strong aria-hidden="true">2.4.</strong> pgrep</a></li><li class="chapter-item expanded "><a href="../monitor/pmap.html"><strong aria-hidden="true">2.5.</strong> pmap</a></li><li class="chapter-item expanded "><a href="../monitor/pstack.html"><strong aria-hidden="true">2.6.</strong> pstack</a></li></ol></li><li class="chapter-item expanded "><a href="../trace_profile/index.html"><strong aria-hidden="true">3.</strong> Trace and Profile</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../trace_profile/strace.html"><strong aria-hidden="true">3.1.</strong> strace</a></li><li class="chapter-item expanded "><a href="../trace_profile/ltrace.html"><strong aria-hidden="true">3.2.</strong> ltrace</a></li><li class="chapter-item expanded "><a href="../trace_profile/perf.html"><strong aria-hidden="true">3.3.</strong> perf</a></li><li class="chapter-item expanded "><a href="../trace_profile/oprofile.html"><strong aria-hidden="true">3.4.</strong> OProfile</a></li><li class="chapter-item expanded "><a href="../trace_profile/time.html"><strong aria-hidden="true">3.5.</strong> time</a></li></ol></li><li class="chapter-item expanded "><a href="../binary/index.html"><strong aria-hidden="true">4.</strong> Binary</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../binary/od.html"><strong aria-hidden="true">4.1.</strong> od</a></li><li class="chapter-item expanded "><a href="../binary/xxd.html"><strong aria-hidden="true">4.2.</strong> xxd</a></li><li class="chapter-item expanded "><a href="../binary/readelf.html"><strong aria-hidden="true">4.3.</strong> readelf</a></li><li class="chapter-item expanded "><a href="../binary/objdump.html"><strong aria-hidden="true">4.4.</strong> objdump</a></li><li class="chapter-item expanded "><a href="../binary/nm.html"><strong aria-hidden="true">4.5.</strong> nm</a></li></ol></li><li class="chapter-item expanded "><a href="../development/index.html"><strong aria-hidden="true">5.</strong> Development</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../development/c++filt.html"><strong aria-hidden="true">5.1.</strong> c++filt</a></li><li class="chapter-item expanded "><a href="../development/c++.html" class="active"><strong aria-hidden="true">5.2.</strong> c++</a></li><li class="chapter-item expanded "><a href="../development/glibc.html"><strong aria-hidden="true">5.3.</strong> glibc</a></li><li class="chapter-item expanded "><a href="../development/gcc.html"><strong aria-hidden="true">5.4.</strong> gcc</a></li><li class="chapter-item expanded "><a href="../development/make.html"><strong aria-hidden="true">5.5.</strong> make</a></li><li class="chapter-item expanded "><a href="../development/ld.so.html"><strong aria-hidden="true">5.6.</strong> ld.so</a></li><li class="chapter-item expanded "><a href="../development/symbolver.html"><strong aria-hidden="true">5.7.</strong> symbol versioning</a></li><li class="chapter-item expanded "><a href="../development/python.html"><strong aria-hidden="true">5.8.</strong> python</a></li></ol></li><li class="chapter-item expanded "><a href="../linux/index.html"><strong aria-hidden="true">6.</strong> Linux</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../linux/systemd.html"><strong aria-hidden="true">6.1.</strong> systemd</a></li><li class="chapter-item expanded "><a href="../linux/coredump.html"><strong aria-hidden="true">6.2.</strong> coredump</a></li><li class="chapter-item expanded "><a href="../linux/ptrace_scope.html"><strong aria-hidden="true">6.3.</strong> ptrace_scope</a></li></ol></li><li class="chapter-item expanded "><a href="../network/index.html"><strong aria-hidden="true">7.</strong> Network</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../network/tcpdump.html"><strong aria-hidden="true">7.1.</strong> tcpdump</a></li></ol></li><li class="chapter-item expanded "><a href="../arch/index.html"><strong aria-hidden="true">8.</strong> Arch</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../arch/x86_64.html"><strong aria-hidden="true">8.1.</strong> x86_64</a></li><li class="chapter-item expanded "><a href="../arch/arm64.html"><strong aria-hidden="true">8.2.</strong> arm64</a></li><li class="chapter-item expanded "><a href="../arch/armv7.html"><strong aria-hidden="true">8.3.</strong> armv7</a></li><li class="chapter-item expanded "><a href="../arch/riscv.html"><strong aria-hidden="true">8.4.</strong> riscv</a></li></ol></li></ol> </div> <div id="sidebar-resize-handle" class="sidebar-resize-handle"></div> </nav> @@ -89,49 +83,42 @@ <div id="page-wrapper" class="page-wrapper"> <div class="page"> - - <div id="menu-bar" class="menu-bar"> - <div id="menu-bar-sticky-container"> - <div class="left-buttons"> - <button id="sidebar-toggle" class="icon-button" type="button" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="sidebar"> - <i class="fa fa-bars"></i> - </button> - <button id="theme-toggle" class="icon-button" type="button" title="Change theme" aria-label="Change theme" aria-haspopup="true" aria-expanded="false" aria-controls="theme-list"> - <i class="fa fa-paint-brush"></i> - </button> - <ul id="theme-list" class="theme-popup" aria-label="Themes" role="menu"> - <li role="none"><button role="menuitem" class="theme" id="light">Light (default)</button></li> - <li role="none"><button role="menuitem" class="theme" id="rust">Rust</button></li> - <li role="none"><button role="menuitem" class="theme" id="coal">Coal</button></li> - <li role="none"><button role="menuitem" class="theme" id="navy">Navy</button></li> - <li 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(Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar"> - <i class="fa fa-search"></i> - </button> - - </div> - - <h1 class="menu-title">Notes</h1> - - <div class="right-buttons"> - <a href="../print.html" title="Print this book" aria-label="Print this book"> - <i id="print-button" class="fa fa-print"></i> - </a> - - <a href="https://github.com/johannst/notes" title="Git repository" aria-label="Git repository"> - <i id="git-repository-button" class="fa fa-github"></i> - </a> - - </div> + <div id="menu-bar-hover-placeholder"></div> + <div id="menu-bar" class="menu-bar sticky bordered"> + <div class="left-buttons"> + <button id="sidebar-toggle" class="icon-button" type="button" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="sidebar"> + <i class="fa fa-bars"></i> + </button> + <button id="theme-toggle" class="icon-button" type="button" title="Change theme" aria-label="Change theme" aria-haspopup="true" aria-expanded="false" aria-controls="theme-list"> + <i class="fa fa-paint-brush"></i> + </button> + <ul id="theme-list" class="theme-popup" aria-label="Themes" role="menu"> + <li role="none"><button role="menuitem" class="theme" id="light">Light (default)</button></li> + <li role="none"><button role="menuitem" class="theme" id="rust">Rust</button></li> + <li role="none"><button role="menuitem" class="theme" id="coal">Coal</button></li> + <li role="none"><button role="menuitem" class="theme" id="navy">Navy</button></li> + <li role="none"><button role="menuitem" class="theme" id="ayu">Ayu</button></li> + </ul> + <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar"> + <i class="fa fa-search"></i> + </button> + </div> + + <h1 class="menu-title">Notes</h1> + + <div class="right-buttons"> + <a href="../print.html" title="Print this book" aria-label="Print this book"> + <i id="print-button" class="fa fa-print"></i> + </a> + <a href="https://github.com/johannst/notes" title="Git repository" aria-label="Git repository"> + <i id="git-repository-button" class="fa fa-github"></i> + </a> </div> </div> - <div id="search-wrapper" class="hidden"> <form id="searchbar-outer" class="searchbar-outer"> - <input type="search" name="search" id="searchbar" name="searchbar" placeholder="Search this book ..." aria-controls="searchresults-outer" aria-describedby="searchresults-header"> + <input type="search" id="searchbar" name="searchbar" placeholder="Search this book ..." aria-controls="searchresults-outer" aria-describedby="searchresults-header"> </form> <div id="searchresults-outer" class="searchresults-outer hidden"> <div id="searchresults-header" class="searchresults-header"></div> @@ -139,8 +126,6 @@ </ul> </div> </div> - - <!-- Apply ARIA attributes after the sidebar and the sidebar toggle button are added to the DOM --> <script type="text/javascript"> document.getElementById('sidebar-toggle').setAttribute('aria-expanded', sidebar === 'visible'); @@ -152,19 +137,132 @@ <div id="content" class="content"> <main> - <h1><a class="header" href="#c" id="c">c++</a></h1> -<h2><a class="header" href="#type-deduction" id="type-deduction">Type deduction</a></h2> + <h1 id="c"><a class="header" href="#c">c++</a></h1> +<h2 id="type-deduction"><a class="header" href="#type-deduction">Type deduction</a></h2> <p>Force compile error to see what <code>auto</code> is deduced to.</p> <pre><code class="language-cpp">auto foo = bar(); // force compile error typename decltype(foo)::_; </code></pre> -<h2><a class="header" href="#variadic-templates-a-hrefhttpsencppreferencecomwcpplanguageparameter_packparameter-packa" id="variadic-templates-a-hrefhttpsencppreferencecomwcpplanguageparameter_packparameter-packa">Variadic templates (<a href="https://en.cppreference.com/w/cpp/language/parameter_pack">parameter pack</a>)</a></h2> -<pre><code class="language-cpp">{{#include c++/meta.cc:3:}} +<h2 id="variadic-templates-parameter-pack"><a class="header" href="#variadic-templates-parameter-pack">Variadic templates (<a href="https://en.cppreference.com/w/cpp/language/parameter_pack">parameter pack</a>)</a></h2> +<pre><code class="language-cpp">#include <iostream> + +// Base case with one parameter. +template<int P> +void show_int() { + printf("%d\n", P); +} + +// General case with at least two parameters, to disambiguate from base case. +template<int P0, int P1, int... Params> +void show_int() { + printf("%d, ", P0); + show_int<P1, Params...>(); +} + +// Base case with one parameter. +template<typename T> +void show(const T& t) { + std::cout << t << '\n'; +} + +// General case with at least two parameters, to disambiguate from base case. +template<typename T0, typename T1, typename... Types> +void show(const T0& t0, const T1& t1, const Types&... types) { + std::cout << t0 << ", "; + show(t1, types...); +} + +int main() { + show_int<1, 2, 3, 4, 5>(); + show(1, 1.0, "foo", 'a'); +} </code></pre> -<h2><a class="header" href="#a-hrefhttpsencppreferencecomwcpplanguagesfinaesfinaea-example-a-hrefhttpsencppreferencecomwcpptypesenable_ifenable_ifa" id="a-hrefhttpsencppreferencecomwcpplanguagesfinaesfinaea-example-a-hrefhttpsencppreferencecomwcpptypesenable_ifenable_ifa"><a href="https://en.cppreference.com/w/cpp/language/sfinae">SFINAE</a> example (<a href="https://en.cppreference.com/w/cpp/types/enable_if">enable_if</a>)</a></h2> -<pre><code class="language-cpp">{{#include c++/meta2.cc:3:}} +<h2 id="sfinae-example-enable_if"><a class="header" href="#sfinae-example-enable_if"><a href="https://en.cppreference.com/w/cpp/language/sfinae">SFINAE</a> example (<a href="https://en.cppreference.com/w/cpp/types/enable_if">enable_if</a>)</a></h2> +<pre><code class="language-cpp">#include <iostream> +#include <type_traits> + +// Helper meta fns. + +template<typename T> +using enable_if_bool = std::enable_if_t<T::value, bool>; + +template<typename T> +using disable_if_bool = std::enable_if_t<!T::value, bool>; + +template<typename T> +using has_dst = std::integral_constant<bool, !std::is_same<typename T::Return, void>::value>; + +// Template meta programming invoke machinery. + +namespace impl { + // Invoke an OPERATION which *USES* a context. + template<typename Ctx, template<typename> class Op, typename... P, + enable_if_bool<typename Op<Ctx>::HasCtx> = true> + typename Op<Ctx>::Return Invoke(const Ctx& C, P... params) { + return Op<Ctx>()(C, params...); + } + + // Invoke an OPERATION which uses *NO* context. + template<typename Ctx, template<typename> class Op, typename... P, + disable_if_bool<typename Op<Ctx>::HasCtx> = true> + typename Op<Ctx>::Return Invoke(const Ctx&, P... params) { + return Op<Ctx>()(params...); + } +} // namespace impl + +// Invoke an OPERATION which *HAS* a DESTINATION with arbitrary number of arguments. +template<typename Ctx, template<typename> class Op, typename... P, + enable_if_bool<has_dst<Op<Ctx>>> = true> +void Invoke(const Ctx& C, P... params) { + std::cout << "Invoke " << Op<Ctx>::Name << '\n'; + typename Op<Ctx>::Return R = impl::Invoke<Ctx, Op>(C, params...); + std::cout << "returned -> " << R << '\n'; +} + +// Invoke an OPERATION which has *NOT* a DESTINATION with arbitrary number of arguments. +template<typename Ctx, template<typename> class Op, typename... P, + disable_if_bool<has_dst<Op<Ctx>>> = true> +void Invoke(const Ctx& C, P... params) { + std::cout << "Invoke " << Op<Ctx>::Name << " without destination." << '\n'; + impl::Invoke<Ctx, Op>(C, params...); +} + +// Custom context. + +struct Ctx { + void out(const char* s, unsigned v) const { printf("%s%x\n", s, v); } +}; + +// Operations to invoke. + +template<typename Ctx> +struct OpA { + using HasCtx = std::false_type; + using Return = int; + static constexpr const char* const Name = "OpA"; + + constexpr Return operator()(int a, int b) const { return a + b; } +}; + +template<typename Ctx> +struct OpB { + using HasCtx = std::true_type; + using Return = void; + static constexpr const char* const Name = "OpB"; + + Return operator()(const Ctx& C, unsigned a) const { C.out("a = ", a); } +}; + +int main() { + Ctx C; + + Invoke<Ctx, OpA>(C, 1, 2); + Invoke<Ctx, OpB>(C, 0xf00du); + + return 0; +} </code></pre> @@ -172,67 +270,38 @@ typename decltype(foo)::_; <nav class="nav-wrapper" aria-label="Page navigation"> <!-- Mobile navigation buttons --> - <a rel="prev" href="../development/c++filt.html" class="mobile-nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left"> <i class="fa fa-angle-left"></i> </a> - - - <a rel="next" href="../development/glibc.html" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right"> <i class="fa fa-angle-right"></i> </a> - - <div style="clear: both"></div> </nav> </div> </div> <nav class="nav-wide-wrapper" aria-label="Page navigation"> - - <a href="../development/c++filt.html" class="nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left"> + <a rel="prev" href="../development/c++filt.html" class="nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left"> <i class="fa fa-angle-left"></i> </a> - - - - <a href="../development/glibc.html" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right"> + <a rel="next" href="../development/glibc.html" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right"> <i class="fa fa-angle-right"></i> </a> - </nav> </div> - - - - - - - <script type="text/javascript"> - window.playpen_copyable = true; + window.playground_copyable = true; </script> - - - - - <script src="../elasticlunr.min.js" type="text/javascript" charset="utf-8"></script> <script src="../mark.min.js" type="text/javascript" charset="utf-8"></script> <script src="../searcher.js" type="text/javascript" charset="utf-8"></script> - - <script src="../clipboard.min.js" type="text/javascript" charset="utf-8"></script> <script src="../highlight.js" type="text/javascript" charset="utf-8"></script> <script src="../book.js" type="text/javascript" charset="utf-8"></script> <!-- Custom JS scripts --> - - - - </body> </html> |