<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta name="generator" content="Asciidoctor 2.0.16">
<meta name="author" content="René Ferdinand Rivera Morell, Isabella Muerte">
<meta name="copyright" content="Copyright 2021 René Ferdinand Rivera Morell">
<title>std::breakpoint</title>
<style>
@import url(https://fonts.googleapis.com/css2?family=Comfortaa&display=swap);
/*! normalize.css v2.1.2 | MIT License | git.io/normalize */
/* ========================================================================== HTML5 display definitions ========================================================================== */
/** Correct `block` display not defined in IE 8/9. */
@import url(https://fonts.googleapis.com/css2?family=IBM+Plex+Mono&display=swap);
article, aside, details, figcaption, figure, footer, header, hgroup, main, nav, section, summary { display: block; }

/** Correct `inline-block` display not defined in IE 8/9. */
audio, canvas, video { display: inline-block; }

/** Prevent modern browsers from displaying `audio` without controls. Remove excess height in iOS 5 devices. */
audio:not([controls]) { display: none; height: 0; }

/** Address `[hidden]` styling not present in IE 8/9. Hide the `template` element in IE, Safari, and Firefox < 22. */
[hidden], template { display: none; }

script { display: none !important; }

/* ========================================================================== Base ========================================================================== */
/** 1. Set default font family to sans-serif. 2. Prevent iOS text size adjust after orientation change, without disabling user zoom. */
html { font-family: sans-serif; /* 1 */ -ms-text-size-adjust: 100%; /* 2 */ -webkit-text-size-adjust: 100%; /* 2 */ }

/** Remove default margin. */
body { margin: 0; }

/* ========================================================================== Links ========================================================================== */
/** Remove the gray background color from active links in IE 10. */
a { background: transparent; }

/** Address `outline` inconsistency between Chrome and other browsers. */
a:focus { outline: thin dotted; }

/** Improve readability when focused and also mouse hovered in all browsers. */
a:active, a:hover { outline: 0; }

/* ========================================================================== Typography ========================================================================== */
/** Address variable `h1` font-size and margin within `section` and `article` contexts in Firefox 4+, Safari 5, and Chrome. */
h1 { font-size: 2em; margin: 0.67em 0; }

/** Address styling not present in IE 8/9, Safari 5, and Chrome. */
abbr[title] { border-bottom: 1px dotted; }

/** Address style set to `bolder` in Firefox 4+, Safari 5, and Chrome. */
b, strong { font-weight: bold; }

/** Address styling not present in Safari 5 and Chrome. */
dfn { font-style: italic; }

/** Address differences between Firefox and other browsers. */
hr { -moz-box-sizing: content-box; box-sizing: content-box; height: 0; }

/** Address styling not present in IE 8/9. */
mark { background: #ff0; color: #000; }

/** Correct font family set oddly in Safari 5 and Chrome. */
code, kbd, pre, samp { font-family: monospace, serif; font-size: 1em; }

/** Improve readability of pre-formatted text in all browsers. */
pre { white-space: pre-wrap; }

/** Set consistent quote types. */
q { quotes: "\201C" "\201D" "\2018" "\2019"; }

/** Address inconsistent and variable font size in all browsers. */
small { font-size: 80%; }

/** Prevent `sub` and `sup` affecting `line-height` in all browsers. */
sub, sup { font-size: 75%; line-height: 0; position: relative; vertical-align: baseline; }

sup { top: -0.5em; }

sub { bottom: -0.25em; }

/* ========================================================================== Embedded content ========================================================================== */
/** Remove border when inside `a` element in IE 8/9. */
img { border: 0; }

/** Correct overflow displayed oddly in IE 9. */
svg:not(:root) { overflow: hidden; }

/* ========================================================================== Figures ========================================================================== */
/** Address margin not present in IE 8/9 and Safari 5. */
figure { margin: 0; }

/* ========================================================================== Forms ========================================================================== */
/** Define consistent border, margin, and padding. */
fieldset { border: 1px solid #c0c0c0; margin: 0 2px; padding: 0.35em 0.625em 0.75em; }

/** 1. Correct `color` not being inherited in IE 8/9. 2. Remove padding so people aren't caught out if they zero out fieldsets. */
legend { border: 0; /* 1 */ padding: 0; /* 2 */ }

/** 1. Correct font family not being inherited in all browsers. 2. Correct font size not being inherited in all browsers. 3. Address margins set differently in Firefox 4+, Safari 5, and Chrome. */
button, input, select, textarea { font-family: inherit; /* 1 */ font-size: 100%; /* 2 */ margin: 0; /* 3 */ }

/** Address Firefox 4+ setting `line-height` on `input` using `!important` in the UA stylesheet. */
button, input { line-height: normal; }

/** Address inconsistent `text-transform` inheritance for `button` and `select`. All other form control elements do not inherit `text-transform` values. Correct `button` style inheritance in Chrome, Safari 5+, and IE 8+. Correct `select` style inheritance in Firefox 4+ and Opera. */
button, select { text-transform: none; }

/** 1. Avoid the WebKit bug in Android 4.0.* where (2) destroys native `audio` and `video` controls. 2. Correct inability to style clickable `input` types in iOS. 3. Improve usability and consistency of cursor style between image-type `input` and others. */
button, html input[type="button"], input[type="reset"], input[type="submit"] { -webkit-appearance: button; /* 2 */ cursor: pointer; /* 3 */ }

/** Re-set default cursor for disabled elements. */
button[disabled], html input[disabled] { cursor: default; }

/** 1. Address box sizing set to `content-box` in IE 8/9. 2. Remove excess padding in IE 8/9. */
input[type="checkbox"], input[type="radio"] { box-sizing: border-box; /* 1 */ padding: 0; /* 2 */ }

/** 1. Address `appearance` set to `searchfield` in Safari 5 and Chrome. 2. Address `box-sizing` set to `border-box` in Safari 5 and Chrome (include `-moz` to future-proof). */
input[type="search"] { -webkit-appearance: textfield; /* 1 */ -moz-box-sizing: content-box; -webkit-box-sizing: content-box; /* 2 */ box-sizing: content-box; }

/** Remove inner padding and search cancel button in Safari 5 and Chrome on OS X. */
input[type="search"]::-webkit-search-cancel-button, input[type="search"]::-webkit-search-decoration { -webkit-appearance: none; }

/** Remove inner padding and border in Firefox 4+. */
button::-moz-focus-inner, input::-moz-focus-inner { border: 0; padding: 0; }

/** 1. Remove default vertical scrollbar in IE 8/9. 2. Improve readability and alignment in all browsers. */
textarea { overflow: auto; /* 1 */ vertical-align: top; /* 2 */ }

/* ========================================================================== Tables ========================================================================== */
/** Remove most spacing between table cells. */
table { border-collapse: collapse; border-spacing: 0; }

meta.foundation-mq-small { font-family: "only screen and (min-width: 768px)"; width: 768px; }

meta.foundation-mq-medium { font-family: "only screen and (min-width:1280px)"; width: 1280px; }

meta.foundation-mq-large { font-family: "only screen and (min-width:1440px)"; width: 1440px; }

*, *:before, *:after { -moz-box-sizing: border-box; -webkit-box-sizing: border-box; box-sizing: border-box; }

html, body { font-size: 100%; }

body { background: #111; color: #aaa; padding: 0; margin: 0; font-family: "Comfortaa", "-apple-system", "BlinkMacSystemFont", "Segoe UI", "Roboto", "Helvetica Neue", "Arial", "sans-serif", "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-weight: normal; font-style: normal; line-height: 1; position: relative; cursor: auto; }

a:hover { cursor: pointer; }

img, object, embed { max-width: 100%; height: auto; }

object, embed { height: 100%; }

img { -ms-interpolation-mode: bicubic; }

#map_canvas img, #map_canvas embed, #map_canvas object, .map_canvas img, .map_canvas embed, .map_canvas object { max-width: none !important; }

.left { float: left !important; }

.right { float: right !important; }

.text-left { text-align: left !important; }

.text-right { text-align: right !important; }

.text-center { text-align: center !important; }

.text-justify { text-align: justify !important; }

.hide { display: none; }

.antialiased { -webkit-font-smoothing: antialiased; }

img { display: inline-block; vertical-align: middle; }

textarea { height: auto; min-height: 50px; }

select { width: 100%; }

p.lead { font-size: 1.21875em; line-height: 1.6; }

.subheader, .admonitionblock td.content > .title, .audioblock > .title, .exampleblock > .title, .imageblock > .title, .listingblock > .title, .literalblock > .title, .stemblock > .title, .openblock > .title, .paragraph > .title, .quoteblock > .title, table.tableblock > .title, .verseblock > .title, .videoblock > .title, .dlist > .title, .olist > .title, .ulist > .title, .qlist > .title, .hdlist > .title { line-height: 1.45; color: #e18400; font-weight: normal; margin-top: 0; margin-bottom: 0.25em; }

/* Typography resets */
div, dl, dt, dd, ul, ol, li, h1, h2, h3, #toctitle, .sidebarblock > .content > .title, h4, h5, h6, pre, form, p, blockquote, th, td { margin: 0; padding: 0; direction: ltr; }

/* Default Link Styles */
a { color: #FA9300; text-decoration: underline; line-height: inherit; }
a:hover, a:focus { color: #e18400; }
a img { border: none; }

/* Default paragraph styles */
p { font-family: inherit; font-weight: normal; font-size: 1em; line-height: 1.6; margin-bottom: 1.25em; text-rendering: optimizeLegibility; }
p aside { font-size: 0.875em; line-height: 1.35; font-style: italic; }

/* Default header styles */
h1, h2, h3, #toctitle, .sidebarblock > .content > .title, h4, h5, h6 { font-family: "Comfortaa", "-apple-system", "BlinkMacSystemFont", "Segoe UI", "Roboto", "Helvetica Neue", "Arial", "sans-serif", "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-weight: 300; font-style: normal; color: #ffa92e; text-rendering: optimizeLegibility; margin-top: 1em; margin-bottom: 0.5em; line-height: 1.0125em; }
h1 small, h2 small, h3 small, #toctitle small, .sidebarblock > .content > .title small, h4 small, h5 small, h6 small { font-size: 60%; color: #ffe8c7; line-height: 0; }

h1 { font-size: 2.125em; }

h2 { font-size: 1.6875em; }

h3, #toctitle, .sidebarblock > .content > .title { font-size: 1.375em; }

h4 { font-size: 1.125em; }

h5 { font-size: 1.125em; }

h6 { font-size: 1em; }

hr { border: solid #2b2b2b; border-width: 1px 0 0; clear: both; margin: 1.25em 0 1.1875em; height: 0; }

/* Helpful Typography Defaults */
em, i { font-style: italic; line-height: inherit; }

strong, b { font-weight: bold; line-height: inherit; }

small { font-size: 60%; line-height: inherit; }

code { font-family: "IBM Plex Mono", "Droid Sans Mono", "DejaVu Sans Mono", "Monospace", monospace; font-weight: normal; color: #ffe8c7; }

/* Lists */
ul, ol, dl { font-size: 1em; line-height: 1.6; margin-bottom: 1.25em; list-style-position: outside; font-family: inherit; }

ul, ol { margin-left: 1.5em; }
ul.no-bullet, ol.no-bullet { margin-left: 1.5em; }

/* Unordered Lists */
ul li ul, ul li ol { margin-left: 1.25em; margin-bottom: 0; font-size: 1em; /* Override nested font-size change */ }
ul.square li ul, ul.circle li ul, ul.disc li ul { list-style: inherit; }
ul.square { list-style-type: square; }
ul.circle { list-style-type: circle; }
ul.disc { list-style-type: disc; }
ul.no-bullet { list-style: none; }

/* Ordered Lists */
ol li ul, ol li ol { margin-left: 1.25em; margin-bottom: 0; }

/* Definition Lists */
dl dt { margin-bottom: 0.3125em; font-weight: bold; }
dl dd { margin-bottom: 1.25em; }

/* Abbreviations */
abbr, acronym { text-transform: uppercase; font-size: 90%; color: #aaa; border-bottom: 1px dotted #ddd; cursor: help; }

abbr { text-transform: none; }

/* Blockquotes */
blockquote { margin: 0 0 1.25em; padding: 0.5625em 1.25em 0 1.1875em; border-left: 1px solid #ddd; }
blockquote cite { display: block; font-size: 0.9375em; color: #aaa; }
blockquote cite:before { content: "\2014 \0020"; }
blockquote cite a, blockquote cite a:visited { color: #aaa; }

blockquote, blockquote p { line-height: 1.6; color: #ffa92e; }

/* Microformats */
.vcard { display: inline-block; margin: 0 0 1.25em 0; border: 1px solid #ddd; padding: 0.625em 0.75em; }
.vcard li { margin: 0; display: block; }
.vcard .fn { font-weight: bold; font-size: 0.9375em; }

.vevent .summary { font-weight: bold; }
.vevent abbr { cursor: auto; text-decoration: none; font-weight: bold; border: none; padding: 0 0.0625em; }

@media only screen and (min-width: 768px) { h1, h2, h3, #toctitle, .sidebarblock > .content > .title, h4, h5, h6 { line-height: 1.2; }
  h1 { font-size: 2.75em; }
  h2 { font-size: 2.3125em; }
  h3, #toctitle, .sidebarblock > .content > .title { font-size: 1.6875em; }
  h4 { font-size: 1.4375em; } }
/* Tables */
table { background: #111; margin-bottom: 1.25em; border: solid 1px #613900; }
table thead, table tfoot { background: #2e1b00; font-weight: bold; }
table thead tr th, table thead tr td, table tfoot tr th, table tfoot tr td { padding: 0.5em 0.625em 0.625em; font-size: inherit; color: #aaa; text-align: left; }
table tr th, table tr td { padding: 0.5625em 0.625em; font-size: inherit; color: #aaa; }
table tr.even, table tr.alt, table tr:nth-of-type(even) { background: #040404; }
table thead tr th, table tfoot tr th, table tbody tr td, table tr td, table tfoot tr td { display: table-cell; line-height: 1.6; }

body { tab-size: 4; word-wrap: anywhere; -moz-osx-font-smoothing: grayscale; -webkit-font-smoothing: antialiased; }

table { word-wrap: normal; }

h1, h2, h3, #toctitle, .sidebarblock > .content > .title, h4, h5, h6 { line-height: 1.2; word-spacing: -0.05em; }
h1 strong, h2 strong, h3 strong, #toctitle strong, .sidebarblock > .content > .title strong, h4 strong, h5 strong, h6 strong { font-weight: 400; }

object, svg { display: inline-block; vertical-align: middle; }

.center { margin-left: auto; margin-right: auto; }

.stretch { width: 100%; }

.clearfix:before, .clearfix:after, .float-group:before, .float-group:after { content: " "; display: table; }
.clearfix:after, .float-group:after { clear: both; }

:not(pre).nobreak { word-wrap: normal; }
:not(pre).nowrap { white-space: nowrap; }
:not(pre).pre-wrap { white-space: pre-wrap; }

:not(pre):not([class^=L]) > code { font-size: 0.875em; font-style: normal !important; letter-spacing: 0; padding: 0.1em 0.5ex; word-spacing: -0.15em; background-color: black; border: 1px solid #111; -webkit-border-radius: 8px; border-radius: 8px; line-height: 1.45; text-rendering: optimizeSpeed; }

pre { color: #FA9300; font-family: "IBM Plex Mono", "Droid Sans Mono", "DejaVu Sans Mono", "Monospace", monospace; line-height: 1.45; text-rendering: optimizeSpeed; }
pre code, pre pre { color: inherit; font-size: inherit; line-height: inherit; }
pre > code { display: block; }

pre.nowrap, pre.nowrap pre { white-space: pre; word-wrap: normal; }

em em { font-style: normal; }

strong strong { font-weight: normal; }

.keyseq { color: #dddddd; }

kbd { font-family: "IBM Plex Mono", "Droid Sans Mono", "DejaVu Sans Mono", "Monospace", monospace; display: inline-block; color: #aaa; font-size: 0.65em; line-height: 1.45; background-color: #f7f7f7; border: 1px solid #ccc; -webkit-border-radius: 3px; border-radius: 3px; -moz-box-shadow: 0 1px 0 rgba(0, 0, 0, 0.2), 0 0 0 0.1em white inset; -webkit-box-shadow: 0 1px 0 rgba(0, 0, 0, 0.2), 0 0 0 0.1em white inset; box-shadow: 0 1px 0 rgba(0, 0, 0, 0.2), 0 0 0 0.1em white inset; margin: 0 0.15em; padding: 0.2em 0.5em; vertical-align: middle; position: relative; top: -0.1em; white-space: nowrap; }

.keyseq kbd:first-child { margin-left: 0; }

.keyseq kbd:last-child { margin-right: 0; }

.menuseq, .menuref { color: #000; }

.menuseq b:not(.caret), .menuref { font-weight: inherit; }

.menuseq { word-spacing: -0.02em; }
.menuseq b.caret { font-size: 1.25em; line-height: 0.8; }
.menuseq i.caret { font-weight: bold; text-align: center; width: 0.45em; }

b.button:before, b.button:after { position: relative; top: -1px; font-weight: normal; }

b.button:before { content: "["; padding: 0 3px 0 2px; }

b.button:after { content: "]"; padding: 0 2px 0 3px; }

p a > code:hover { color: #ffddae; }

#header, #content, #footnotes, #footer { width: 100%; margin-left: auto; margin-right: auto; margin-top: 0; margin-bottom: 0; max-width: 62.5em; *zoom: 1; position: relative; padding-left: 0.9375em; padding-right: 0.9375em; }
#header:before, #header:after, #content:before, #content:after, #footnotes:before, #footnotes:after, #footer:before, #footer:after { content: " "; display: table; }
#header:after, #content:after, #footnotes:after, #footer:after { clear: both; }

#content { margin-top: 1.25em; }

#content:before { content: none; }

#header > h1:first-child { color: #ffa92e; margin-top: 2.25rem; margin-bottom: 0; }
#header > h1:first-child + #toc { margin-top: 8px; border-top: 1px solid #2b2b2b; }
#header > h1:only-child, body.toc2 #header > h1:nth-last-child(2) { border-bottom: 1px solid #2b2b2b; padding-bottom: 8px; }
#header .details { border-bottom: 1px solid #2b2b2b; line-height: 1.45; padding-top: 0.25em; padding-bottom: 0.25em; padding-left: 0.25em; color: #aaa; display: -ms-flexbox; display: -webkit-flex; display: flex; -ms-flex-flow: row wrap; -webkit-flex-flow: row wrap; flex-flow: row wrap; }
#header .details span:first-child { margin-left: -0.125em; }
#header .details span.email a { color: #ffa92e; }
#header .details br { display: none; }
#header .details br + span:before { content: "\00a0\2013\00a0"; }
#header .details br + span.author:before { content: "\00a0\22c5\00a0"; color: #ffa92e; }
#header .details br + span#revremark:before { content: "\00a0|\00a0"; }
#header #revnumber { text-transform: capitalize; }
#header #revnumber:after { content: "\00a0"; }

#content > h1:first-child:not([class]) { color: #ffa92e; border-bottom: 1px solid #2b2b2b; padding-bottom: 8px; margin-top: 0; padding-top: 1rem; margin-bottom: 1.25rem; }

#toc { border-bottom: 1px solid #1e1e1e; padding-bottom: 0.5em; }
#toc > ul { margin-left: 0.125em; }
#toc ul.sectlevel0 > li > a { font-style: italic; }
#toc ul.sectlevel0 ul.sectlevel1 { margin: 0.5em 0; }
#toc ul { font-family: "Comfortaa", "-apple-system", "BlinkMacSystemFont", "Segoe UI", "Roboto", "Helvetica Neue", "Arial", "sans-serif", "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; list-style-type: none; }
#toc li { line-height: 1.3334; margin-top: 0.3334em; }
#toc a { text-decoration: none; }
#toc a:active { text-decoration: underline; }

#toctitle { color: #e18400; font-size: 1.2em; }

@media only screen and (min-width: 768px) { #toctitle { font-size: 1.375em; }
  body.toc2 { padding-left: 15em; padding-right: 0; }
  #toc.toc2 { margin-top: 0 !important; background: black; position: fixed; width: 15em; left: 0; top: 0; border-right: 1px solid #1e1e1e; border-top-width: 0 !important; border-bottom-width: 0 !important; z-index: 1000; padding: 1.25em 1em; height: 100%; overflow: auto; }
  #toc.toc2 #toctitle { margin-top: 0; margin-bottom: 0.8rem; font-size: 1.2em; }
  #toc.toc2 > ul { font-size: 0.9em; margin-bottom: 0; }
  #toc.toc2 ul ul { margin-left: 0; padding-left: 1em; }
  #toc.toc2 ul.sectlevel0 ul.sectlevel1 { padding-left: 0; margin-top: 0.5em; margin-bottom: 0.5em; }
  body.toc2.toc-right { padding-left: 0; padding-right: 15em; }
  body.toc2.toc-right #toc.toc2 { border-right-width: 0; border-left: 1px solid #1e1e1e; left: auto; right: 0; } }
@media only screen and (min-width: 1280px) { body.toc2 { padding-left: 20em; padding-right: 0; }
  #toc.toc2 { width: 20em; }
  #toc.toc2 #toctitle { font-size: 1.375em; }
  #toc.toc2 > ul { font-size: 0.95em; }
  #toc.toc2 ul ul { padding-left: 1.25em; }
  body.toc2.toc-right { padding-left: 0; padding-right: 20em; } }
#content #toc { border-style: solid; border-width: 1px; border-color: black; margin-bottom: 1.25em; padding: 1.25em; background: black; -webkit-border-radius: 8px; border-radius: 8px; }
#content #toc > :first-child { margin-top: 0; }
#content #toc > :last-child { margin-bottom: 0; }

#footer { max-width: none; background: #aaa; padding: 1.25em; }

#footer-text { color: #555555; line-height: 1.44; }

#content { margin-bottom: 0.625em; }

.sect1 { padding-bottom: 0.625em; }

@media only screen and (min-width: 768px) { #content { margin-bottom: 1.25em; }
  .sect1 { padding-bottom: 1.25em; } }
.sect1:last-child { padding-bottom: 0; }

.sect1 + .sect1 { border-top: 1px solid #1e1e1e; }

#content h1 > a.anchor, h2 > a.anchor, h3 > a.anchor, #toctitle > a.anchor, .sidebarblock > .content > .title > a.anchor, h4 > a.anchor, h5 > a.anchor, h6 > a.anchor { position: absolute; z-index: 1001; width: 1.5ex; margin-left: -1.5ex; display: block; text-decoration: none !important; visibility: hidden; text-align: center; font-weight: normal; }
#content h1 > a.anchor:before, h2 > a.anchor:before, h3 > a.anchor:before, #toctitle > a.anchor:before, .sidebarblock > .content > .title > a.anchor:before, h4 > a.anchor:before, h5 > a.anchor:before, h6 > a.anchor:before { content: "\00A7"; font-size: 0.85em; display: block; padding-top: 0.1em; }
#content h1:hover > a.anchor, #content h1 > a.anchor:hover, h2:hover > a.anchor, h2 > a.anchor:hover, h3:hover > a.anchor, #toctitle:hover > a.anchor, .sidebarblock > .content > .title:hover > a.anchor, h3 > a.anchor:hover, #toctitle > a.anchor:hover, .sidebarblock > .content > .title > a.anchor:hover, h4:hover > a.anchor, h4 > a.anchor:hover, h5:hover > a.anchor, h5 > a.anchor:hover, h6:hover > a.anchor, h6 > a.anchor:hover { visibility: visible; }
#content h1 > a.link, h2 > a.link, h3 > a.link, #toctitle > a.link, .sidebarblock > .content > .title > a.link, h4 > a.link, h5 > a.link, h6 > a.link { color: #ffa92e; text-decoration: none; }
#content h1 > a.link:hover, h2 > a.link:hover, h3 > a.link:hover, #toctitle > a.link:hover, .sidebarblock > .content > .title > a.link:hover, h4 > a.link:hover, h5 > a.link:hover, h6 > a.link:hover { color: #ff9e15; }

details, .audioblock, .imageblock, .literalblock, .listingblock, .stemblock, .videoblock { margin-bottom: 1.25em; }

details > summary:first-of-type { cursor: pointer; display: list-item; outline: none; margin-bottom: 0.75em; }

.admonitionblock td.content > .title, .audioblock > .title, .exampleblock > .title, .imageblock > .title, .listingblock > .title, .literalblock > .title, .stemblock > .title, .openblock > .title, .paragraph > .title, .quoteblock > .title, table.tableblock > .title, .verseblock > .title, .videoblock > .title, .dlist > .title, .olist > .title, .ulist > .title, .qlist > .title, .hdlist > .title { text-rendering: optimizeLegibility; text-align: left; font-family: "Comfortaa", "-apple-system", "BlinkMacSystemFont", "Segoe UI", "Roboto", "Helvetica Neue", "Arial", "sans-serif", "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 1rem; font-style: italic; }

table.tableblock.fit-content > caption.title { white-space: nowrap; width: 0; }

.paragraph.lead > p, #preamble > .sectionbody > [class="paragraph"]:first-of-type p { font-size: 1.21875em; line-height: 1.6; color: #ffa92e; }

table.tableblock #preamble > .sectionbody > [class="paragraph"]:first-of-type p { font-size: inherit; }

.admonitionblock > table { border-collapse: separate; border: 0; background: none; width: 100%; }
.admonitionblock > table td.icon { text-align: center; width: 80px; }
.admonitionblock > table td.icon img { max-width: none; }
.admonitionblock > table td.icon .title { font-weight: bold; font-family: "Comfortaa", "-apple-system", "BlinkMacSystemFont", "Segoe UI", "Roboto", "Helvetica Neue", "Arial", "sans-serif", "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; text-transform: uppercase; }
.admonitionblock > table td.content { padding-left: 1.125em; padding-right: 1.25em; border-left: 1px solid #2b2b2b; color: #aaa; word-wrap: anywhere; }
.admonitionblock > table td.content > :last-child > :last-child { margin-bottom: 0; }

.exampleblock > .content { border-style: solid; border-width: 1px; border-color: black; margin-bottom: 1.25em; padding: 1.25em; background: #111; -webkit-border-radius: 8px; border-radius: 8px; }
.exampleblock > .content > :first-child { margin-top: 0; }
.exampleblock > .content > :last-child { margin-bottom: 0; }

.sidebarblock { border-style: solid; border-width: 1px; border-color: black; margin-bottom: 1.25em; padding: 1.25em; background: black; -webkit-border-radius: 8px; border-radius: 8px; }
.sidebarblock > :first-child { margin-top: 0; }
.sidebarblock > :last-child { margin-bottom: 0; }
.sidebarblock > .content > .title { color: #e18400; margin-top: 0; text-align: center; }

.exampleblock > .content > :last-child > :last-child, .exampleblock > .content .olist > ol > li:last-child > :last-child, .exampleblock > .content .ulist > ul > li:last-child > :last-child, .exampleblock > .content .qlist > ol > li:last-child > :last-child, .sidebarblock > .content > :last-child > :last-child, .sidebarblock > .content .olist > ol > li:last-child > :last-child, .sidebarblock > .content .ulist > ul > li:last-child > :last-child, .sidebarblock > .content .qlist > ol > li:last-child > :last-child { margin-bottom: 0; }

.literalblock pre, .listingblock > .content > pre { border: 1px solid #2e1b00; -webkit-border-radius: 8px; border-radius: 8px; overflow-x: auto; padding: 1em; font-size: 0.8125em; }
@media only screen and (min-width: 768px) { .literalblock pre, .listingblock > .content > pre { font-size: 0.90625em; } }
@media only screen and (min-width: 1280px) { .literalblock pre, .listingblock > .content > pre { font-size: 1em; } }

.literalblock pre, .listingblock > .content > pre:not(.highlight), .listingblock > .content > pre[class="highlight"], .listingblock > .content > pre[class^="highlight "] { background: black; }

.literalblock.output pre { color: black; background-color: #FA9300; }

.listingblock > .content { position: relative; }

.listingblock code[data-lang]:before { display: none; content: attr(data-lang); position: absolute; font-size: 0.75em; top: 0.425rem; right: 0.5rem; line-height: 1; text-transform: uppercase; color: inherit; opacity: 0.5; }

.listingblock:hover code[data-lang]:before { display: block; }

.listingblock.terminal pre .command:before { content: attr(data-prompt); padding-right: 0.5em; color: inherit; opacity: 0.5; }

.listingblock.terminal pre .command:not([data-prompt]):before { content: "$"; }

.listingblock pre.highlightjs { padding: 0; }
.listingblock pre.highlightjs > code { padding: 1em; -webkit-border-radius: 8px; border-radius: 8px; }

.prettyprint { background: black; }

pre.prettyprint .linenums { line-height: 1.45; margin-left: 2em; }

pre.prettyprint li { background: none; list-style-type: inherit; padding-left: 0; }

pre.prettyprint li code[data-lang]:before { opacity: 1; }

pre.prettyprint li:not(:first-child) code[data-lang]:before { display: none; }

table.linenotable { border-collapse: separate; border: 0; margin-bottom: 0; background: none; }
table.linenotable td[class] { color: inherit; vertical-align: top; padding: 0; line-height: inherit; white-space: normal; }
table.linenotable td.code { padding-left: 0.75em; }
table.linenotable td.linenos { border-right: 1px solid currentColor; opacity: 0.35; padding-right: 0.5em; }

pre.pygments .lineno { border-right: 1px solid currentColor; opacity: 0.35; display: inline-block; margin-right: 0.75em; }
pre.pygments .lineno:before { content: ""; margin-right: -0.125em; }

.quoteblock { margin: 0 1em 1.25em 1.5em; display: table; }
.quoteblock:not(.excerpt) > .title { margin-left: -1.5em; margin-bottom: 0.75em; }
.quoteblock blockquote, .quoteblock p { color: #ffa92e; font-size: 1.15rem; line-height: 1.75; word-spacing: 0.1em; letter-spacing: 0; font-style: italic; text-align: justify; }
.quoteblock blockquote { margin: 0; padding: 0; border: 0; }
.quoteblock blockquote:before { content: "\201c"; float: left; font-size: 2.75em; font-weight: bold; line-height: 0.6em; margin-left: -0.6em; color: #e18400; text-shadow: 0 1px 2px rgba(0, 0, 0, 0.1); }
.quoteblock blockquote > .paragraph:last-child p { margin-bottom: 0; }
.quoteblock .attribution { margin-top: 0.75em; margin-right: 0.5ex; text-align: right; }

.verseblock { margin: 0 1em 1.25em 1em; }
.verseblock pre { font-family: "Open Sans", "DejaVu Sans", sans; font-size: 1.15rem; color: #ffa92e; font-weight: 300; text-rendering: optimizeLegibility; }
.verseblock pre strong { font-weight: 400; }
.verseblock .attribution { margin-top: 1.25rem; margin-left: 0.5ex; }

.quoteblock .attribution, .verseblock .attribution { font-size: 0.9375em; line-height: 1.45; font-style: italic; }
.quoteblock .attribution br, .verseblock .attribution br { display: none; }
.quoteblock .attribution cite, .verseblock .attribution cite { display: block; letter-spacing: -0.025em; color: #aaa; }

.quoteblock.abstract blockquote:before, .quoteblock.excerpt blockquote:before, .quoteblock .quoteblock blockquote:before { display: none; }
.quoteblock.abstract blockquote, .quoteblock.abstract p, .quoteblock.excerpt blockquote, .quoteblock.excerpt p, .quoteblock .quoteblock blockquote, .quoteblock .quoteblock p { line-height: 1.6; word-spacing: 0; }
.quoteblock.abstract { margin: 0 1em 1.25em 1em; display: block; }
.quoteblock.abstract > .title { margin: 0 0 0.375em 0; font-size: 1.15em; text-align: center; }
.quoteblock.excerpt > blockquote, .quoteblock .quoteblock { padding: 0 0 0.25em 1em; border-left: 0.25em solid #2b2b2b; }
.quoteblock.excerpt, .quoteblock .quoteblock { margin-left: 0; }
.quoteblock.excerpt blockquote, .quoteblock.excerpt p, .quoteblock .quoteblock blockquote, .quoteblock .quoteblock p { color: inherit; font-size: 1.0625rem; }
.quoteblock.excerpt .attribution, .quoteblock .quoteblock .attribution { color: inherit; text-align: left; margin-right: 0; }

p.tableblock:last-child { margin-bottom: 0; }

td.tableblock > .content { margin-bottom: 1.25em; word-wrap: anywhere; }
td.tableblock > .content > :last-child { margin-bottom: -1.25em; }

table.tableblock, th.tableblock, td.tableblock { border: 0 solid #613900; }

table.grid-all > * > tr > * { border-width: 1px; }

table.grid-cols > * > tr > * { border-width: 0 1px; }

table.grid-rows > * > tr > * { border-width: 1px 0; }

table.frame-all { border-width: 1px; }

table.frame-ends { border-width: 1px 0; }

table.frame-sides { border-width: 0 1px; }

table.frame-none > colgroup + * > :first-child > *, table.frame-sides > colgroup + * > :first-child > * { border-top-width: 0; }

table.frame-none > :last-child > :last-child > *, table.frame-sides > :last-child > :last-child > * { border-bottom-width: 0; }

table.frame-none > * > tr > :first-child, table.frame-ends > * > tr > :first-child { border-left-width: 0; }

table.frame-none > * > tr > :last-child, table.frame-ends > * > tr > :last-child { border-right-width: 0; }

table.stripes-all tr, table.stripes-odd tr:nth-of-type(odd), table.stripes-even tr:nth-of-type(even), table.stripes-hover tr:hover { background: #040404; }

th.halign-left, td.halign-left { text-align: left; }

th.halign-right, td.halign-right { text-align: right; }

th.halign-center, td.halign-center { text-align: center; }

th.valign-top, td.valign-top { vertical-align: top; }

th.valign-bottom, td.valign-bottom { vertical-align: bottom; }

th.valign-middle, td.valign-middle { vertical-align: middle; }

table thead th, table tfoot th { font-weight: bold; }

tbody tr th { display: table-cell; line-height: 1.6; background: #2e1b00; }

tbody tr th, tbody tr th p, tfoot tr th, tfoot tr th p { color: #aaa; font-weight: bold; }

p.tableblock > code:only-child { background: none; padding: 0; }

p.tableblock { font-size: 1em; }

ol { margin-left: 1.75em; }

ul li ol { margin-left: 1.5em; }

dl dd { margin-left: 1.125em; }

dl dd:last-child, dl dd:last-child > :last-child { margin-bottom: 0; }

ol > li p, ul > li p, ul dd, ol dd, .olist .olist, .ulist .ulist, .ulist .olist, .olist .ulist { margin-bottom: 0.625em; }

ul.checklist, ul.none, ol.none, ul.no-bullet, ol.no-bullet, ol.unnumbered, ul.unstyled, ol.unstyled { list-style-type: none; }

ul.no-bullet, ol.no-bullet, ol.unnumbered { margin-left: 0.625em; }

ul.unstyled, ol.unstyled { margin-left: 0; }

ul.checklist { margin-left: 0.625em; }

ul.checklist li > p:first-child > .fa-square-o:first-child, ul.checklist li > p:first-child > .fa-check-square-o:first-child { width: 1.25em; font-size: 0.8em; position: relative; bottom: 0.125em; }

ul.checklist li > p:first-child > input[type="checkbox"]:first-child { margin-right: 0.25em; }

ul.inline { display: -ms-flexbox; display: -webkit-box; display: flex; -ms-flex-flow: row wrap; -webkit-flex-flow: row wrap; flex-flow: row wrap; list-style: none; margin: 0 0 0.625em -1.25em; }

ul.inline > li { margin-left: 1.25em; }

.unstyled dl dt { font-weight: normal; font-style: normal; }

ol.arabic { list-style-type: decimal; }

ol.decimal { list-style-type: decimal-leading-zero; }

ol.loweralpha { list-style-type: lower-alpha; }

ol.upperalpha { list-style-type: upper-alpha; }

ol.lowerroman { list-style-type: lower-roman; }

ol.upperroman { list-style-type: upper-roman; }

ol.lowergreek { list-style-type: lower-greek; }

.hdlist > table, .colist > table { border: 0; background: none; }
.hdlist > table > tbody > tr, .colist > table > tbody > tr { background: none; }

td.hdlist1, td.hdlist2 { vertical-align: top; padding: 0 0.625em; }

td.hdlist1 { font-weight: bold; padding-bottom: 1.25em; }

td.hdlist2 { word-wrap: anywhere; }

.literalblock + .colist, .listingblock + .colist { margin-top: -0.5em; }

.colist td:not([class]):first-child { padding: 0.4em 0.75em 0 0.75em; line-height: 1; vertical-align: top; }
.colist td:not([class]):first-child img { max-width: none; }
.colist td:not([class]):last-child { padding: 0.25em 0; }

.thumb, .th { line-height: 0; display: inline-block; border: solid 4px #fff; -webkit-box-shadow: 0 0 0 1px #ddd; box-shadow: 0 0 0 1px #ddd; }

.imageblock.left { margin: 0.25em 0.625em 1.25em 0; }
.imageblock.right { margin: 0.25em 0 1.25em 0.625em; }
.imageblock > .title { margin-bottom: 0; }
.imageblock.thumb, .imageblock.th { border-width: 6px; }
.imageblock.thumb > .title, .imageblock.th > .title { padding: 0 0.125em; }

.image.left, .image.right { margin-top: 0.25em; margin-bottom: 0.25em; display: inline-block; line-height: 0; }
.image.left { margin-right: 0.625em; }
.image.right { margin-left: 0.625em; }

a.image { text-decoration: none; display: inline-block; }
a.image object { pointer-events: none; }

sup.footnote, sup.footnoteref { font-size: 0.875em; position: static; vertical-align: super; }
sup.footnote a, sup.footnoteref a { text-decoration: none; }
sup.footnote a:active, sup.footnoteref a:active { text-decoration: underline; }

#footnotes { padding-top: 0.75em; padding-bottom: 0.75em; margin-bottom: 0.625em; }
#footnotes hr { width: 20%; min-width: 6.25em; margin: -0.25em 0 0.75em 0; border-width: 1px 0 0 0; }
#footnotes .footnote { padding: 0 0.375em 0 0.225em; line-height: 1.3334; font-size: 0.875em; margin-left: 1.2em; margin-bottom: 0.2em; }
#footnotes .footnote a:first-of-type { font-weight: bold; text-decoration: none; margin-left: -1.05em; }
#footnotes .footnote:last-of-type { margin-bottom: 0; }
#content #footnotes { margin-top: -0.625em; margin-bottom: 0; padding: 0.75em 0; }

.gist .file-data > table { border: 0; background: #fff; width: 100%; margin-bottom: 0; }
.gist .file-data > table td.line-data { width: 99%; }

div.unbreakable { page-break-inside: avoid; }

.big { font-size: larger; }

.small { font-size: smaller; }

.underline { text-decoration: underline; }

.overline { text-decoration: overline; }

.line-through { text-decoration: line-through; }

.aqua { color: #00bfbf; }

.aqua-background { background-color: #00fafa; }

.black { color: black; }

.black-background { background-color: black; }

.blue { color: #0000bf; }

.blue-background { background-color: #0000fa; }

.fuchsia { color: #bf00bf; }

.fuchsia-background { background-color: #fa00fa; }

.gray { color: #606060; }

.gray-background { background-color: #7d7d7d; }

.green { color: #006000; }

.green-background { background-color: #007d00; }

.lime { color: #00bf00; }

.lime-background { background-color: #00fa00; }

.maroon { color: #600000; }

.maroon-background { background-color: #7d0000; }

.navy { color: #000060; }

.navy-background { background-color: #00007d; }

.olive { color: #606000; }

.olive-background { background-color: #7d7d00; }

.purple { color: #600060; }

.purple-background { background-color: #7d007d; }

.red { color: #bf0000; }

.red-background { background-color: #fa0000; }

.silver { color: #909090; }

.silver-background { background-color: #bcbcbc; }

.teal { color: #006060; }

.teal-background { background-color: #007d7d; }

.white { color: #bfbfbf; }

.white-background { background-color: #fafafa; }

.yellow { color: #bfbf00; }

.yellow-background { background-color: #fafa00; }

span.icon > .fa { cursor: default; }
a span.icon > .fa { cursor: inherit; }

.admonitionblock td.icon [class^="fa icon-"] { font-size: 2.5em; text-shadow: 0px 0px 5px #c77500; cursor: default; }
.admonitionblock td.icon .icon-note:before { content: "\f05a"; color: #bc6e00; }
.admonitionblock td.icon .icon-tip:before { content: "\f0eb"; text-shadow: 1px 1px 2px rgba(155, 155, 0, 0.8); color: #111; }
.admonitionblock td.icon .icon-warning:before { content: "\f071"; color: #bf6900; }
.admonitionblock td.icon .icon-caution:before { content: "\f06d"; color: #bf3400; }
.admonitionblock td.icon .icon-important:before { content: "\f06a"; color: #bf0000; }

.conum[data-value] { display: inline-block; color: #fff !important; background-color: #aaa; -webkit-border-radius: 50%; border-radius: 50%; text-align: center; font-size: 0.75em; width: 1.67em; height: 1.67em; line-height: 1.67em; font-family: "Open Sans", "DejaVu Sans", sans-serif; font-style: normal; font-weight: bold; }
.conum[data-value] * { color: #fff !important; }
.conum[data-value] + b { display: none; }
.conum[data-value]:after { content: attr(data-value); }
pre .conum[data-value] { position: relative; top: -0.125em; }

b.conum * { color: inherit !important; }

.conum:not([data-value]):empty { display: none; }

dt, th.tableblock, td.content, div.footnote { text-rendering: optimizeLegibility; }

h1, h2, p, td.content, span.alt { letter-spacing: -0.01em; }

p strong, td.content strong, div.footnote strong { letter-spacing: -0.005em; }

strong { text-shadow: 0px 0px 2px; }

p, blockquote, dt, td.content, span.alt { font-size: 1.0625rem; }

p { margin-bottom: 1.25rem; }

.sidebarblock p, .sidebarblock dt, .sidebarblock td.content, p.tableblock { font-size: 1em; }

.exampleblock > .content { border-color: #2e1b00; -moz-box-shadow: 0 1px 4px #2e1b00; -webkit-box-shadow: 0 1px 4px #2e1b00; box-shadow: 0 1px 4px #2e1b00; }

.admonitionblock .icon .title { font-size: 2.5em; text-shadow: 0px 0px 5px #c77500; }

.caution .icon .title { color: #6610f2; }

.important .icon .title { color: #e74c3c; }

.note .icon .title { color: #3498db; }

.tip .icon .title { color: #00bc8c; }

.warning .icon .title { color: #f39c12; }

pre.pygments { background: #000 !important; }

.literalblock pre, .listingblock > .content > pre { font-size: 0.875em; }
@media only screen and (min-width: 768px) { .literalblock pre, .listingblock > .content > pre { font-size: 0.875em; } }
@media only screen and (min-width: 1280px) { .literalblock pre, .listingblock > .content > pre { font-size: 0.875em; } }

.literalblock pre, .listingblock > .content > pre { background: black !important; }

.sidebarblock { border-color: #2e1b00; }

a { color: inherit; }

#header .details { color: #c77500; }

#toc { scrollbar-width: none; scrollbar-color: #613900 transparent; }

#toc:hover { scrollbar-width: thin; scrollbar-color: #c77500 #2e1b00; }

#toc::-webkit-scrollbar { width: 0px; }

#toc::-webkit-scrollbar-thumb { background: #613900; }

#toc::-webkit-scrollbar-track { background: transparent; }

#toc:hover::-webkit-scrollbar { width: 6px; }

#toc:hover::-webkit-scrollbar-thumb { background: #c77500; }

#toc:hover::-webkit-scrollbar-track { background: #2e1b00; }

.print-only { display: none !important; }

@page { margin: 1.25cm 0.75cm; }
@media print { * { -moz-box-shadow: none !important; -webkit-box-shadow: none !important; box-shadow: none !important; text-shadow: none !important; }
  html { font-size: 80%; }
  a { color: inherit !important; text-decoration: underline !important; }
  a.bare, a[href^="#"], a[href^="mailto:"] { text-decoration: none !important; }
  a[href^="http:"]:not(.bare):after, a[href^="https:"]:not(.bare):after { content: "(" attr(href) ")"; display: inline-block; font-size: 0.875em; padding-left: 0.25em; }
  abbr[title]:after { content: " (" attr(title) ")"; }
  pre, blockquote, tr, img, object, svg { page-break-inside: avoid; }
  thead { display: table-header-group; }
  svg { max-width: 100%; }
  p, blockquote, dt, td.content { font-size: 1em; orphans: 3; widows: 3; }
  h2, h3, #toctitle, .sidebarblock > .content > .title, #toctitle, .sidebarblock > .content > .title { page-break-after: avoid; }
  #header, #content, #footnotes, #footer { max-width: none; }
  #toc, .sidebarblock, .exampleblock > .content { background: none !important; }
  #toc { border-bottom: 1px solid #2b2b2b !important; padding-bottom: 0 !important; }
  body.book #header { text-align: center; }
  body.book #header > h1:first-child { border: 0 !important; margin: 2.5em 0 1em 0; }
  body.book #header .details { border: 0 !important; display: block; padding: 0 !important; }
  body.book #header .details span:first-child { margin-left: 0 !important; }
  body.book #header .details br { display: block; }
  body.book #header .details br + span:before { content: none !important; }
  body.book #toc { border: 0 !important; text-align: left !important; padding: 0 !important; margin: 0 !important; }
  body.book #toc, body.book #preamble, body.book h1.sect0, body.book .sect1 > h2 { page-break-before: always; }
  .literalblock pre, .literalblock pre[class], .listingblock pre, .listingblock pre[class] { border: 0 !important; }
  .listingblock code[data-lang]:before { display: block; }
  #footer { padding: 0 0.9375em; }
  .hide-on-print { display: none !important; }
  .print-only { display: block !important; }
  .hide-for-print { display: none !important; }
  .show-for-print { display: inherit !important; } }
@media print, amzn-kf8 { #header > h1:first-child { margin-top: 1.25rem; }
  .sect1 { padding: 0 !important; }
  .sect1 + .sect1 { border: 0; }
  #footer { background: none; }
  #footer-text { color: #aaa; font-size: 0.9em; } }
@media amzn-kf8 { #header, #content, #footnotes, #footer { padding: 0; } }
.menubar { position: fixed; display: block; top: 0px; left: 0px; right: 0px; z-index: 99; background-color: black; border-bottom: 1px solid #2e1b00; padding: 10px; text-align: center; }

.menubar p { margin: 0px; }

.menubar image { padding-right: 1em; }

.menubar-item { padding-left: 1em; }

@media print { .menubar { display: none; } }

</style>
<style>
pre.rouge table td { padding: 5px; }
pre.rouge table pre { margin: 0; }
pre.rouge, pre.rouge .w {
  color: #586e75;
}
pre.rouge .err {
  color: #002b36;
  background-color: #dc322f;
}
pre.rouge .c, pre.rouge .ch, pre.rouge .cd, pre.rouge .cm, pre.rouge .cpf, pre.rouge .c1, pre.rouge .cs {
  color: #657b83;
}
pre.rouge .cp {
  color: #b58900;
}
pre.rouge .nt {
  color: #b58900;
}
pre.rouge .o, pre.rouge .ow {
  color: #93a1a1;
}
pre.rouge .p, pre.rouge .pi {
  color: #93a1a1;
}
pre.rouge .gi {
  color: #859900;
}
pre.rouge .gd {
  color: #dc322f;
}
pre.rouge .gh {
  color: #268bd2;
  background-color: #002b36;
  font-weight: bold;
}
pre.rouge .k, pre.rouge .kn, pre.rouge .kp, pre.rouge .kr, pre.rouge .kv {
  color: #6c71c4;
}
pre.rouge .kc {
  color: #cb4b16;
}
pre.rouge .kt {
  color: #cb4b16;
}
pre.rouge .kd {
  color: #cb4b16;
}
pre.rouge .s, pre.rouge .sb, pre.rouge .sc, pre.rouge .dl, pre.rouge .sd, pre.rouge .s2, pre.rouge .sh, pre.rouge .sx, pre.rouge .s1 {
  color: #859900;
}
pre.rouge .sa {
  color: #6c71c4;
}
pre.rouge .sr {
  color: #2aa198;
}
pre.rouge .si {
  color: #d33682;
}
pre.rouge .se {
  color: #d33682;
}
pre.rouge .nn {
  color: #b58900;
}
pre.rouge .nc {
  color: #b58900;
}
pre.rouge .no {
  color: #b58900;
}
pre.rouge .na {
  color: #268bd2;
}
pre.rouge .m, pre.rouge .mb, pre.rouge .mf, pre.rouge .mh, pre.rouge .mi, pre.rouge .il, pre.rouge .mo, pre.rouge .mx {
  color: #859900;
}
pre.rouge .ss {
  color: #859900;
}
</style>
</head>
<body class="article toc2 toc-left">
<div id="header">
<h1><code>std::breakpoint</code></h1>
<div class="details">
<span id="author" class="author">René Ferdinand Rivera Morell, Isabella Muerte</span><br>
<span id="email" class="email"><a href="mailto:grafikrobot@gmail.com">grafikrobot@gmail.com</a></span><br>
<span id="revnumber"> P2514R0,</span>
<span id="revdate">2021-12-30</span>
</div>
<div id="toc" class="toc2">
<div id="toctitle">Table of Contents</div>
<ul class="sectlevel1">
<li><a href="#_abstract">1. Abstract</a></li>
<li><a href="#_revision_history">2. Revision History</a></li>
<li><a href="#_motivation">3. Motivation</a></li>
<li><a href="#_design_decisions">4. Design Decisions</a></li>
<li><a href="#_implementation_experience">5. Implementation Experience</a></li>
<li><a href="#_wording">6. Wording</a></li>
<li><a href="#_acknowledgements">7. Acknowledgements</a></li>
</ul>
</div>
</div>
<div id="content">
<div id="preamble">
<div class="sectionbody">
<style>
.ins {
	border-left: solid 0.4em green;
	padding-left: 1em;
	text-decoration: underline solid green;
}
</style>
<div class="dlist">
<dl>
<dt class="hdlist1">Document number: </dt>
<dd>
<p>ISO/IEC/JTC1/SC22/WG21/P2514R0</p>
</dd>
<dt class="hdlist1">Date: </dt>
<dd>
<p>2021-12-30</p>
</dd>
<dt class="hdlist1">Audience: </dt>
<dd>
<p>SG15, LEWG</p>
</dd>
<dt class="hdlist1">Reply-to: </dt>
<dd>
<p>René Ferdinand Rivera Morell, Isabella Muerte, <a href="mailto:grafikrobot@gmail.com">grafikrobot@gmail.com</a></p>
</dd>
<dt class="hdlist1">Project: </dt>
<dd>
<p>ISO/IEC JTC1/SC22/WG21 14882: Programming Language — C&#43;&#43;</p>
</dd>
</dl>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_abstract"><a class="anchor" href="#_abstract"></a>1. Abstract</h2>
<div class="sectionbody">
<div class="paragraph">
<p>This paper proposes a new function, <code>std::breakpoint</code>, that causes a program to
stop or "break" execution when it is being debugged to aid in software
development.</p>
</div>
<div class="paragraph">
<p>This is a successor paper to P1279.
<sup class="footnote" id="_footnote_P1279">[<a id="_footnoteref_1" class="footnote" href="#_footnotedef_1" title="View footnote.">1</a>]</sup></p>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_revision_history"><a class="anchor" href="#_revision_history"></a>2. Revision History</h2>
<div class="sectionbody">
<div class="sect2">
<h3 id="_revision_0_january_2022"><a class="anchor" href="#_revision_0_january_2022"></a>2.1. Revision 0 (January 2022)</h3>
<div class="paragraph">
<p>Initial text based on P1279.
<sup class="footnoteref">[<a class="footnote" href="#_footnotedef_1" title="View footnote.">1</a>]</sup></p>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_motivation"><a class="anchor" href="#_motivation"></a>3. Motivation</h2>
<div class="sectionbody">
<div class="paragraph">
<p>Setting breakpoints inside of a debugger can be difficult and confusing for
newcomers to C&#43;&#43;. Rather than having to learn C&#43;&#43;, they have to learn a special
syntax just to place a breakpoint in the exact spot they want, or rely on the
interface of an IDE. At the end of the day, an average programmer just wants to
place a breakpoint so that their program stops when under the watchful eye of a
debugger.</p>
</div>
<div class="paragraph">
<p>Having this facility also helps in advanced software development environments
as it allows for runtime control of breakpoints beyond what might be available
from a debugger. In particular to allow programmatic control on what runtime
sensitive conditions to break into the debugger.</p>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_design_decisions"><a class="anchor" href="#_design_decisions"></a>4. Design Decisions</h2>
<div class="sectionbody">
<div class="paragraph">
<p>The goal of the <code>std::breakpoint</code> function is to "break" when being debugged
but to act as though it is a no-op when it is executing normally. This might
seem difficult in practice, but nearly every platform and various debuggers
supports something to this effect. However, some platforms have caveats that
make implementing this "break when being debugged" behavior hard to implement
correctly.</p>
</div>
<div class="paragraph">
<p>The <code>std::breakpoint</code> function is intended to go into a <code>&lt;debugging&gt;</code> header.</p>
</div>
<div class="sect2">
<h3 id="_impact_on_the_standard"><a class="anchor" href="#_impact_on_the_standard"></a>4.1. Impact On the Standard</h3>
<div class="paragraph">
<p>This proposal adds a utility header and a single function the implementation
of which is widely available across compilers and platforms.</p>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_implementation_experience"><a class="anchor" href="#_implementation_experience"></a>5. Implementation Experience</h2>
<div class="sectionbody">
<div class="paragraph">
<p>In addition to the prototype implementation
<sup class="footnote">[<a id="_footnoteref_2" class="footnote" href="#_footnotedef_2" title="View footnote.">2</a>]</sup>
there are the following, full or partial, equivalent implementations:</p>
</div>
<div class="ulist">
<ul>
<li>
<p>The Microsoft Visual compiler provides a <code>__debugbreak</code> function that
implements an unconditional break.
<sup class="footnote">[<a id="_footnoteref_3" class="footnote" href="#_footnotedef_3" title="View footnote.">3</a>]</sup></p>
</li>
<li>
<p>GNU Compiler Collection provides a <code>__builtin_trap</code> function that
implements an unconditional break.
<sup class="footnote">[<a id="_footnoteref_4" class="footnote" href="#_footnotedef_4" title="View footnote.">4</a>]</sup></p>
</li>
<li>
<p>Clang provides a <code>__builtin_debugtrap</code> function that implements an
unconditional break.</p>
</li>
<li>
<p>The arm Keil armcc compiler provides a <code>__breakpoint</code> function that
implements an unconditional break.
<sup class="footnote">[<a id="_footnoteref_5" class="footnote" href="#_footnotedef_5" title="View footnote.">5</a>]</sup></p>
</li>
<li>
<p>Unreal Engine 4 implements a similar facility as a macro.</p>
</li>
</ul>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_wording"><a class="anchor" href="#_wording"></a>6. Wording</h2>
<div class="sectionbody">
<div class="paragraph">
<p>Wording is relative to <a href="https://wg21.link/N4868">N4868</a>.
<sup class="footnote">[<a id="_footnoteref_6" class="footnote" href="#_footnotedef_6" title="View footnote.">6</a>]</sup></p>
</div>
<div class="sect2">
<h3 id="_library"><a class="anchor" href="#_library"></a>6.1. Library</h3>
<div class="paragraph">
<p>Add a new entry to General utilities library summary [utilities.summary] table.</p>
</div>
<div class="openblock ins text-justify">
<div class="content">
<table class="tableblock frame-all grid-all stretch">
<colgroup>
<col style="width: 33.3333%;">
<col style="width: 33.3333%;">
<col style="width: 33.3334%;">
</colgroup>
<tbody>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">[debugging]</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Debugging</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>&lt;debugging&gt;</code></p></td>
</tr>
</tbody>
</table>
</div>
</div>
<div class="paragraph">
<p>Add section to General utilities library [utilities].</p>
</div>
<div class="sect3 ins text-justify][">
<h4 id="dbg"><a class="anchor" href="#dbg"></a>6.1.1. Debugging <span class="right">[<a href="#dbg">debugging</a>]</span></h4>
<div class="sect4">
<h5 id="dbg-gen"><a class="anchor" href="#dbg-gen"></a>6.1.1.1. In general <span class="right">[<a href="#dbg-gen">debugging.general</a>]</span></h5>
<div class="paragraph">
<p>Subclause [debugging] describes the debugging library that provides functionality
to introspect and interact with a debugger that is executing and monitoring the
running program.</p>
</div>
</div>
<div class="sect4">
<h5 id="dbg-syn"><a class="anchor" href="#dbg-syn"></a>6.1.1.2. Header <code>&lt;debugging&gt;</code> synopsis <span class="right">[<a href="#dbg-syn">debugging.syn</a>]</span></h5>
<div class="listingblock">
<div class="content">
<pre class="rouge highlight"><code data-lang="c++"><span class="k">namespace</span> <span class="n">std</span> <span class="p">{</span>
	<span class="c1">// [debugging.utility], utility</span>
	<span class="kt">void</span> <span class="n">breakpoint</span><span class="p">()</span> <span class="k">noexcept</span><span class="p">;</span>
<span class="p">}</span></code></pre>
</div>
</div>
</div>
<div class="sect4">
<h5 id="dbg-util"><a class="anchor" href="#dbg-util"></a>6.1.1.3. Utility <span class="right">[<a href="#dbg-util">debugging.utility</a>]</span></h5>
<div class="paragraph">
<p><code>void breakpoint() noexcept;</code></p>
</div>
<div class="paragraph">
<p><em>Remarks</em>: When this function is executed, it first must perform an
implementation defined check to see if the program is currently running under a
debugger. If it is, the program&#8217;s execution is temporarily halted and execution
is handed to the debugger until such a time as: the program is terminated by
the debugger or, the debugger hands execution back to the program.</p>
</div>
</div>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_acknowledgements"><a class="anchor" href="#_acknowledgements"></a>7. Acknowledgements</h2>
<div class="sectionbody">
<div class="paragraph">
<p>Thank you Isabella Muerte for the initial proposal from which this paper steals
a good amount of the text.</p>
</div>
</div>
</div>
</div>
<div id="footnotes">
<hr>
<div class="footnote" id="_footnotedef_1">
<a href="#_footnoteref_1">1</a>. P1279 std::breakpoint, <em>Isabella Muerte</em> 2018-10-05 (<a href="https://wg21.link/P1279" class="bare">https://wg21.link/P1279</a>)
</div>
<div class="footnote" id="_footnotedef_2">
<a href="#_footnoteref_2">2</a>. Debugging prototype implementation (<a href="https://github.com/grafikrobot/debugging" class="bare">https://github.com/grafikrobot/debugging</a>)
</div>
<div class="footnote" id="_footnotedef_3">
<a href="#_footnoteref_3">3</a>. Microsoft compiler <code>__debugbreak</code> intrinsic (<a href="https://docs.microsoft.com/en-us/cpp/intrinsics/debugbreak" class="bare">https://docs.microsoft.com/en-us/cpp/intrinsics/debugbreak</a>)
</div>
<div class="footnote" id="_footnotedef_4">
<a href="#_footnoteref_4">4</a>. GNU GCC Other Built-in Functions Provided by GCC (<a href="https://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html" class="bare">https://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html</a>)
</div>
<div class="footnote" id="_footnotedef_5">
<a href="#_footnoteref_5">5</a>. armKEIL <code>__breakpoint</code> intrinsic (<a href="https://www.keil.com/support/man/docs/armcc/armcc_chr1359124993371.htm" class="bare">https://www.keil.com/support/man/docs/armcc/armcc_chr1359124993371.htm</a>)
</div>
<div class="footnote" id="_footnotedef_6">
<a href="#_footnoteref_6">6</a>. N4868 Working Draft, Standard for Programming Language C++ 2020-10-18 (<a href="https://wg21.link/N4868" class="bare">https://wg21.link/N4868</a>)
</div>
</div>
</body>
</html>