476 lines
14 KiB
JavaScript
476 lines
14 KiB
JavaScript
/*!
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* The reveal.js markdown plugin. Handles parsing of
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* markdown inside of presentations as well as loading
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* of external markdown documents.
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*/
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import marked from 'marked'
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const DEFAULT_SLIDE_SEPARATOR = '\r?\n---\r?\n',
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DEFAULT_NOTES_SEPARATOR = 'notes?:',
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DEFAULT_ELEMENT_ATTRIBUTES_SEPARATOR = '\\\.element\\\s*?(.+?)$',
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DEFAULT_SLIDE_ATTRIBUTES_SEPARATOR = '\\\.slide:\\\s*?(\\\S.+?)$';
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const SCRIPT_END_PLACEHOLDER = '__SCRIPT_END__';
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const CODE_LINE_NUMBER_REGEX = /\[([\s\d,|-]*)\]/;
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const HTML_ESCAPE_MAP = {
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'&': '&',
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'<': '<',
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'>': '>',
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'"': '"',
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"'": '''
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};
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const Plugin = () => {
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// The reveal.js instance this plugin is attached to
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let deck;
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/**
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* Retrieves the markdown contents of a slide section
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* element. Normalizes leading tabs/whitespace.
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*/
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function getMarkdownFromSlide( section ) {
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// look for a <script> or <textarea data-template> wrapper
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var template = section.querySelector( '[data-template]' ) || section.querySelector( 'script' );
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// strip leading whitespace so it isn't evaluated as code
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var text = ( template || section ).textContent;
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// restore script end tags
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text = text.replace( new RegExp( SCRIPT_END_PLACEHOLDER, 'g' ), '</script>' );
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var leadingWs = text.match( /^\n?(\s*)/ )[1].length,
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leadingTabs = text.match( /^\n?(\t*)/ )[1].length;
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if( leadingTabs > 0 ) {
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text = text.replace( new RegExp('\\n?\\t{' + leadingTabs + '}','g'), '\n' );
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}
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else if( leadingWs > 1 ) {
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text = text.replace( new RegExp('\\n? {' + leadingWs + '}', 'g'), '\n' );
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}
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return text;
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}
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/**
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* Given a markdown slide section element, this will
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* return all arguments that aren't related to markdown
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* parsing. Used to forward any other user-defined arguments
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* to the output markdown slide.
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*/
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function getForwardedAttributes( section ) {
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var attributes = section.attributes;
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var result = [];
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for( var i = 0, len = attributes.length; i < len; i++ ) {
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var name = attributes[i].name,
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value = attributes[i].value;
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// disregard attributes that are used for markdown loading/parsing
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if( /data\-(markdown|separator|vertical|notes)/gi.test( name ) ) continue;
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if( value ) {
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result.push( name + '="' + value + '"' );
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}
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else {
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result.push( name );
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}
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}
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return result.join( ' ' );
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}
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/**
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* Inspects the given options and fills out default
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* values for what's not defined.
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*/
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function getSlidifyOptions( options ) {
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options = options || {};
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options.separator = options.separator || DEFAULT_SLIDE_SEPARATOR;
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options.notesSeparator = options.notesSeparator || DEFAULT_NOTES_SEPARATOR;
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options.attributes = options.attributes || '';
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return options;
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}
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/**
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* Helper function for constructing a markdown slide.
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*/
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function createMarkdownSlide( content, options ) {
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options = getSlidifyOptions( options );
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var notesMatch = content.split( new RegExp( options.notesSeparator, 'mgi' ) );
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if( notesMatch.length === 2 ) {
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content = notesMatch[0] + '<aside class="notes">' + marked(notesMatch[1].trim()) + '</aside>';
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}
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// prevent script end tags in the content from interfering
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// with parsing
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content = content.replace( /<\/script>/g, SCRIPT_END_PLACEHOLDER );
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return '<script type="text/template">' + content + '</script>';
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}
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/**
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* Parses a data string into multiple slides based
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* on the passed in separator arguments.
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*/
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function slidify( markdown, options ) {
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options = getSlidifyOptions( options );
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var separatorRegex = new RegExp( options.separator + ( options.verticalSeparator ? '|' + options.verticalSeparator : '' ), 'mg' ),
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horizontalSeparatorRegex = new RegExp( options.separator );
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var matches,
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lastIndex = 0,
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isHorizontal,
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wasHorizontal = true,
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content,
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sectionStack = [];
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// iterate until all blocks between separators are stacked up
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while( matches = separatorRegex.exec( markdown ) ) {
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var notes = null;
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// determine direction (horizontal by default)
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isHorizontal = horizontalSeparatorRegex.test( matches[0] );
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if( !isHorizontal && wasHorizontal ) {
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// create vertical stack
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sectionStack.push( [] );
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}
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// pluck slide content from markdown input
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content = markdown.substring( lastIndex, matches.index );
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if( isHorizontal && wasHorizontal ) {
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// add to horizontal stack
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sectionStack.push( content );
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}
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else {
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// add to vertical stack
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sectionStack[sectionStack.length-1].push( content );
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}
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lastIndex = separatorRegex.lastIndex;
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wasHorizontal = isHorizontal;
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}
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// add the remaining slide
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( wasHorizontal ? sectionStack : sectionStack[sectionStack.length-1] ).push( markdown.substring( lastIndex ) );
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var markdownSections = '';
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// flatten the hierarchical stack, and insert <section data-markdown> tags
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for( var i = 0, len = sectionStack.length; i < len; i++ ) {
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// vertical
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if( sectionStack[i] instanceof Array ) {
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markdownSections += '<section '+ options.attributes +'>';
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sectionStack[i].forEach( function( child ) {
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markdownSections += '<section data-markdown>' + createMarkdownSlide( child, options ) + '</section>';
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} );
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markdownSections += '</section>';
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}
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else {
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markdownSections += '<section '+ options.attributes +' data-markdown>' + createMarkdownSlide( sectionStack[i], options ) + '</section>';
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}
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}
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return markdownSections;
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}
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/**
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* Parses any current data-markdown slides, splits
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* multi-slide markdown into separate sections and
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* handles loading of external markdown.
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*/
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function processSlides( scope ) {
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return new Promise( function( resolve ) {
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var externalPromises = [];
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[].slice.call( scope.querySelectorAll( 'section[data-markdown]:not([data-markdown-parsed])') ).forEach( function( section, i ) {
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if( section.getAttribute( 'data-markdown' ).length ) {
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externalPromises.push( loadExternalMarkdown( section ).then(
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// Finished loading external file
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function( xhr, url ) {
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section.outerHTML = slidify( xhr.responseText, {
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separator: section.getAttribute( 'data-separator' ),
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verticalSeparator: section.getAttribute( 'data-separator-vertical' ),
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notesSeparator: section.getAttribute( 'data-separator-notes' ),
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attributes: getForwardedAttributes( section )
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});
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},
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// Failed to load markdown
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function( xhr, url ) {
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section.outerHTML = '<section data-state="alert">' +
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'ERROR: The attempt to fetch ' + url + ' failed with HTTP status ' + xhr.status + '.' +
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'Check your browser\'s JavaScript console for more details.' +
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'<p>Remember that you need to serve the presentation HTML from a HTTP server.</p>' +
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'</section>';
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}
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) );
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}
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else {
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section.outerHTML = slidify( getMarkdownFromSlide( section ), {
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separator: section.getAttribute( 'data-separator' ),
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verticalSeparator: section.getAttribute( 'data-separator-vertical' ),
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notesSeparator: section.getAttribute( 'data-separator-notes' ),
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attributes: getForwardedAttributes( section )
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});
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}
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});
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Promise.all( externalPromises ).then( resolve );
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} );
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}
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function loadExternalMarkdown( section ) {
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return new Promise( function( resolve, reject ) {
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var xhr = new XMLHttpRequest(),
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url = section.getAttribute( 'data-markdown' );
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var datacharset = section.getAttribute( 'data-charset' );
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// see https://developer.mozilla.org/en-US/docs/Web/API/element.getAttribute#Notes
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if( datacharset != null && datacharset != '' ) {
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xhr.overrideMimeType( 'text/html; charset=' + datacharset );
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}
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xhr.onreadystatechange = function( section, xhr ) {
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if( xhr.readyState === 4 ) {
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// file protocol yields status code 0 (useful for local debug, mobile applications etc.)
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if ( ( xhr.status >= 200 && xhr.status < 300 ) || xhr.status === 0 ) {
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resolve( xhr, url );
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}
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else {
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reject( xhr, url );
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}
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}
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}.bind( this, section, xhr );
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xhr.open( 'GET', url, true );
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try {
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xhr.send();
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}
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catch ( e ) {
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console.warn( 'Failed to get the Markdown file ' + url + '. Make sure that the presentation and the file are served by a HTTP server and the file can be found there. ' + e );
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resolve( xhr, url );
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}
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} );
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}
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/**
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* Check if a node value has the attributes pattern.
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* If yes, extract it and add that value as one or several attributes
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* to the target element.
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*
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* You need Cache Killer on Chrome to see the effect on any FOM transformation
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* directly on refresh (F5)
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* http://stackoverflow.com/questions/5690269/disabling-chrome-cache-for-website-development/7000899#answer-11786277
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*/
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function addAttributeInElement( node, elementTarget, separator ) {
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var mardownClassesInElementsRegex = new RegExp( separator, 'mg' );
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var mardownClassRegex = new RegExp( "([^\"= ]+?)=\"([^\"]+?)\"|(data-[^\"= ]+?)(?=[\" ])", 'mg' );
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var nodeValue = node.nodeValue;
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var matches,
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matchesClass;
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if( matches = mardownClassesInElementsRegex.exec( nodeValue ) ) {
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var classes = matches[1];
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nodeValue = nodeValue.substring( 0, matches.index ) + nodeValue.substring( mardownClassesInElementsRegex.lastIndex );
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node.nodeValue = nodeValue;
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while( matchesClass = mardownClassRegex.exec( classes ) ) {
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if( matchesClass[2] ) {
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elementTarget.setAttribute( matchesClass[1], matchesClass[2] );
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} else {
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elementTarget.setAttribute( matchesClass[3], "" );
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}
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}
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return true;
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}
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return false;
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}
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/**
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* Add attributes to the parent element of a text node,
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* or the element of an attribute node.
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*/
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function addAttributes( section, element, previousElement, separatorElementAttributes, separatorSectionAttributes ) {
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if ( element != null && element.childNodes != undefined && element.childNodes.length > 0 ) {
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var previousParentElement = element;
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for( var i = 0; i < element.childNodes.length; i++ ) {
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var childElement = element.childNodes[i];
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if ( i > 0 ) {
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var j = i - 1;
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while ( j >= 0 ) {
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var aPreviousChildElement = element.childNodes[j];
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if ( typeof aPreviousChildElement.setAttribute == 'function' && aPreviousChildElement.tagName != "BR" ) {
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previousParentElement = aPreviousChildElement;
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break;
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}
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j = j - 1;
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}
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}
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var parentSection = section;
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if( childElement.nodeName == "section" ) {
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parentSection = childElement ;
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previousParentElement = childElement ;
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}
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if ( typeof childElement.setAttribute == 'function' || childElement.nodeType == Node.COMMENT_NODE ) {
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addAttributes( parentSection, childElement, previousParentElement, separatorElementAttributes, separatorSectionAttributes );
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}
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}
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}
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if ( element.nodeType == Node.COMMENT_NODE ) {
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if ( addAttributeInElement( element, previousElement, separatorElementAttributes ) == false ) {
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addAttributeInElement( element, section, separatorSectionAttributes );
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}
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}
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}
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/**
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* Converts any current data-markdown slides in the
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* DOM to HTML.
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*/
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function convertSlides() {
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var sections = deck.getRevealElement().querySelectorAll( '[data-markdown]:not([data-markdown-parsed])');
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[].slice.call( sections ).forEach( function( section ) {
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section.setAttribute( 'data-markdown-parsed', true )
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var notes = section.querySelector( 'aside.notes' );
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var markdown = getMarkdownFromSlide( section );
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section.innerHTML = marked( markdown );
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addAttributes( section, section, null, section.getAttribute( 'data-element-attributes' ) ||
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section.parentNode.getAttribute( 'data-element-attributes' ) ||
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DEFAULT_ELEMENT_ATTRIBUTES_SEPARATOR,
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section.getAttribute( 'data-attributes' ) ||
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section.parentNode.getAttribute( 'data-attributes' ) ||
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DEFAULT_SLIDE_ATTRIBUTES_SEPARATOR);
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// If there were notes, we need to re-add them after
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// having overwritten the section's HTML
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if( notes ) {
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section.appendChild( notes );
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}
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} );
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return Promise.resolve();
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}
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function escapeForHTML( input ) {
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return input.replace( /([&<>'"])/g, char => HTML_ESCAPE_MAP[char] );
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}
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return {
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id: 'markdown',
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/**
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* Starts processing and converting Markdown within the
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* current reveal.js deck.
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*/
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init: function( reveal ) {
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deck = reveal;
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let { renderer, animateLists, ...markedOptions } = deck.getConfig().markdown || {};
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if( !renderer ) {
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renderer = new marked.Renderer();
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renderer.code = ( code, language ) => {
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// Off by default
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let lineNumbers = '';
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// Users can opt in to show line numbers and highlight
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// specific lines.
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// ```javascript [] show line numbers
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// ```javascript [1,4-8] highlights lines 1 and 4-8
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if( CODE_LINE_NUMBER_REGEX.test( language ) ) {
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lineNumbers = language.match( CODE_LINE_NUMBER_REGEX )[1].trim();
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lineNumbers = `data-line-numbers="${lineNumbers}"`;
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language = language.replace( CODE_LINE_NUMBER_REGEX, '' ).trim();
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}
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// Escape before this gets injected into the DOM to
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// avoid having the HTML parser alter our code before
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// highlight.js is able to read it
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code = escapeForHTML( code );
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return `<pre><code ${lineNumbers} class="${language}">${code}</code></pre>`;
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};
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}
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if( animateLists === true ) {
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renderer.listitem = text => `<li class="fragment">${text}</li>`;
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}
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marked.setOptions( {
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renderer,
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...markedOptions
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} );
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return processSlides( deck.getRevealElement() ).then( convertSlides );
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},
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// TODO: Do these belong in the API?
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processSlides: processSlides,
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convertSlides: convertSlides,
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slidify: slidify,
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marked: marked
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}
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};
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export default Plugin;
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