lca20-bt/plugin/markdown/markdown.js

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/**
* The reveal.js markdown plugin. Handles parsing of
* markdown inside of presentations as well as loading
* of external markdown documents.
*/
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(function(){
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if( typeof marked === 'undefined' ) {
throw 'The reveal.js Markdown plugin requires marked to be loaded';
}
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if( typeof hljs !== 'undefined' ) {
marked.setOptions({
highlight: function( lang, code ) {
return hljs.highlightAuto( lang, code ).value;
}
});
}
/**
* Retrieves the markdown contents of a slide section
* element. Normalizes leading tabs/whitespace.
*/
function getMarkdownFromSlide( section ) {
var template = section.querySelector( 'script' );
// strip leading whitespace so it isn't evaluated as code
var text = ( template || section ).textContent;
var leadingWs = text.match( /^\n?(\s*)/ )[1].length,
leadingTabs = text.match( /^\n?(\t*)/ )[1].length;
if( leadingTabs > 0 ) {
text = text.replace( new RegExp('\\n?\\t{' + leadingTabs + '}','g'), '\n' );
}
else if( leadingWs > 1 ) {
text = text.replace( new RegExp('\\n? {' + leadingWs + '}','g'), '\n' );
}
return text;
}
/**
* Given a markdown slide section element, this will
* return all arguments that aren't related to markdown
* parsing. Used to forward any other user-defined arguments
* to the output markdown slide.
*/
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function getForwardedAttributes( section ) {
var attributes = section.attributes;
var result = [];
for( var i = 0, len = attributes.length; i < len; i++ ) {
var name = attributes[i].name,
value = attributes[i].value;
// disregard attributes that are used for markdown loading/parsing
if( /data\-(markdown|separator|vertical|notes)/gi.test( name ) ) continue;
if( value ) {
result.push( name + '=' + value );
}
else {
result.push( name );
}
}
return result.join( ' ' );
}
/**
* Helper function for constructing a markdown slide.
*/
function createMarkdownSlide( data ) {
var content = data.content || data;
if( data.notes ) {
content += '<aside class="notes" data-markdown>' + data.notes + '</aside>';
}
return '<script type="text/template">' + content + '</script>';
}
/**
* Parses a data string into multiple slides based
* on the passed in separator arguments.
*/
function slidifyMarkdown( markdown, options ) {
options = options || {};
options.separator = options.separator || '^\n---\n$';
options.notesSeparator = options.notesSeparator || 'note:';
options.attributes = options.attributes || '';
var separatorRegex = new RegExp( options.separator + ( options.verticalSeparator ? '|' + options.verticalSeparator : '' ), 'mg' ),
horizontalSeparatorRegex = new RegExp( options.separator ),
notesSeparatorRegex = new RegExp( options.notesSeparator, 'mgi' );
var matches,
noteMatch,
lastIndex = 0,
isHorizontal,
wasHorizontal = true,
content,
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notes,
slide,
sectionStack = [];
// iterate until all blocks between separators are stacked up
while( matches = separatorRegex.exec( markdown ) ) {
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notes = null;
// determine direction (horizontal by default)
isHorizontal = horizontalSeparatorRegex.test( matches[0] );
if( !isHorizontal && wasHorizontal ) {
// create vertical stack
sectionStack.push( [] );
}
// pluck slide content from markdown input
content = markdown.substring( lastIndex, matches.index );
noteMatch = content.split( notesSeparatorRegex );
if( noteMatch.length === 2 ) {
content = noteMatch[0];
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notes = noteMatch[1].trim();
}
slide = {
content: content,
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notes: notes || ''
};
if( isHorizontal && wasHorizontal ) {
// add to horizontal stack
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sectionStack.push( slide );
}
else {
// add to vertical stack
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sectionStack[sectionStack.length-1].push( slide );
}
lastIndex = separatorRegex.lastIndex;
wasHorizontal = isHorizontal;
}
// add the remaining slide
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( wasHorizontal ? sectionStack : sectionStack[sectionStack.length-1] ).push( markdown.substring( lastIndex ) );
var markdownSections = '';
// flatten the hierarchical stack, and insert <section data-markdown> tags
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for( var i = 0, len = sectionStack.length; i < len; i++ ) {
// vertical
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if( sectionStack[i].propertyIsEnumerable( length ) && typeof sectionStack[i].splice === 'function' ) {
markdownSections += '<section '+ options.attributes +'>' +
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'<section data-markdown>' + sectionStack[i].map( createMarkdownSlide ).join( '</section><section data-markdown>' ) + '</section>' +
'</section>';
}
else {
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markdownSections += '<section '+ options.attributes +' data-markdown>' + createMarkdownSlide( sectionStack[i] ) + '</section>';
}
}
return markdownSections;
}
function loadExternalMarkdown() {
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var sections = document.querySelectorAll( '[data-markdown]'),
section;
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for( var i = 0, len = sections.length; i < len; i++ ) {
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section = sections[i];
if( section.getAttribute( 'data-markdown' ).length ) {
var xhr = new XMLHttpRequest(),
url = section.getAttribute( 'data-markdown' );
datacharset = section.getAttribute( 'data-charset' );
// see https://developer.mozilla.org/en-US/docs/Web/API/element.getAttribute#Notes
if( datacharset != null && datacharset != '' ) {
xhr.overrideMimeType( 'text/html; charset=' + datacharset );
}
xhr.onreadystatechange = function() {
if( xhr.readyState === 4 ) {
if ( xhr.status >= 200 && xhr.status < 300 ) {
section.outerHTML = slidifyMarkdown( xhr.responseText, {
separator: section.getAttribute( 'data-separator' ),
verticalSeparator: section.getAttribute( 'data-vertical' ),
notesSeparator: section.getAttribute( 'data-notes' ),
attributes: getForwardedAttributes( section )
});
}
else {
section.outerHTML = '<section data-state="alert">' +
'ERROR: The attempt to fetch ' + url + ' failed with HTTP status ' + xhr.status + '.' +
'Check your browser\'s JavaScript console for more details.' +
'<p>Remember that you need to serve the presentation HTML from a HTTP server.</p>' +
'</section>';
}
}
};
xhr.open( 'GET', url, false );
try {
xhr.send();
}
catch ( e ) {
alert( '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 );
}
}
else if( section.getAttribute( 'data-separator' ) ) {
section.outerHTML = slidifyMarkdown( getMarkdownFromSlide( section ), {
separator: section.getAttribute( 'data-separator' ),
verticalSeparator: section.getAttribute( 'data-vertical' ),
notesSeparator: section.getAttribute( 'data-notes' ),
attributes: getForwardedAttributes( section )
});
}
}
}
function convertMarkdownToHTML() {
var sections = document.querySelectorAll( '[data-markdown]');
for( var i = 0, len = sections.length; i < len; i++ ) {
var section = sections[i];
var notes = section.querySelector( 'aside.notes' );
var markdown = getMarkdownFromSlide( section );
section.innerHTML = marked( markdown );
// If there were notes, we need to re-add them after
// having overwritten the section's HTML
if( notes ) {
section.appendChild( notes );
}
}
}
loadExternalMarkdown();
convertMarkdownToHTML();
})();