node has the
+ * 'data-line-numbers' attribute we also generate slide
+ * numbers.
+ *
+ * If the block contains multiple line highlight steps,
+ * we clone the block and create a fragment for each step.
+ */
+ highlightBlock: function( block ) {
+
+ hljs.highlightElement( block );
+
+ // Don't generate line numbers for empty code blocks
+ if( block.innerHTML.trim().length === 0 ) return;
+
+ if( block.hasAttribute( 'data-line-numbers' ) ) {
+ hljs.lineNumbersBlock( block, { singleLine: true } );
+
+ var scrollState = { currentBlock: block };
+
+ // If there is more than one highlight step, generate
+ // fragments
+ var highlightSteps = Plugin.deserializeHighlightSteps( block.getAttribute( 'data-line-numbers' ) );
+ if( highlightSteps.length > 1 ) {
+
+ // If the original code block has a fragment-index,
+ // each clone should follow in an incremental sequence
+ var fragmentIndex = parseInt( block.getAttribute( 'data-fragment-index' ), 10 );
+
+ if( typeof fragmentIndex !== 'number' || isNaN( fragmentIndex ) ) {
+ fragmentIndex = null;
+ }
+
+ // Generate fragments for all steps except the original block
+ highlightSteps.slice(1).forEach( function( highlight ) {
+
+ var fragmentBlock = block.cloneNode( true );
+ fragmentBlock.setAttribute( 'data-line-numbers', Plugin.serializeHighlightSteps( [ highlight ] ) );
+ fragmentBlock.classList.add( 'fragment' );
+ block.parentNode.appendChild( fragmentBlock );
+ Plugin.highlightLines( fragmentBlock );
+
+ if( typeof fragmentIndex === 'number' ) {
+ fragmentBlock.setAttribute( 'data-fragment-index', fragmentIndex );
+ fragmentIndex += 1;
+ }
+ else {
+ fragmentBlock.removeAttribute( 'data-fragment-index' );
+ }
+
+ // Scroll highlights into view as we step through them
+ fragmentBlock.addEventListener( 'visible', Plugin.scrollHighlightedLineIntoView.bind( Plugin, fragmentBlock, scrollState ) );
+ fragmentBlock.addEventListener( 'hidden', Plugin.scrollHighlightedLineIntoView.bind( Plugin, fragmentBlock.previousSibling, scrollState ) );
+
+ } );
+
+ block.removeAttribute( 'data-fragment-index' );
+ block.setAttribute( 'data-line-numbers', Plugin.serializeHighlightSteps( [ highlightSteps[0] ] ) );
+
+ }
+
+ // Scroll the first highlight into view when the slide
+ // becomes visible. Note supported in IE11 since it lacks
+ // support for Element.closest.
+ var slide = typeof block.closest === 'function' ? block.closest( 'section:not(.stack)' ) : null;
+ if( slide ) {
+ var scrollFirstHighlightIntoView = function() {
+ Plugin.scrollHighlightedLineIntoView( block, scrollState, true );
+ slide.removeEventListener( 'visible', scrollFirstHighlightIntoView );
+ }
+ slide.addEventListener( 'visible', scrollFirstHighlightIntoView );
+ }
+
+ Plugin.highlightLines( block );
+
+ }
+
+ },
+
+ /**
+ * Animates scrolling to the first highlighted line
+ * in the given code block.
+ */
+ scrollHighlightedLineIntoView: function( block, scrollState, skipAnimation ) {
+
+ cancelAnimationFrame( scrollState.animationFrameID );
+
+ // Match the scroll position of the currently visible
+ // code block
+ if( scrollState.currentBlock ) {
+ block.scrollTop = scrollState.currentBlock.scrollTop;
+ }
+
+ // Remember the current code block so that we can match
+ // its scroll position when showing/hiding fragments
+ scrollState.currentBlock = block;
+
+ var highlightBounds = this.getHighlightedLineBounds( block )
+ var viewportHeight = block.offsetHeight;
+
+ // Subtract padding from the viewport height
+ var blockStyles = getComputedStyle( block );
+ viewportHeight -= parseInt( blockStyles.paddingTop ) + parseInt( blockStyles.paddingBottom );
+
+ // Scroll position which centers all highlights
+ var startTop = block.scrollTop;
+ var targetTop = highlightBounds.top + ( Math.min( highlightBounds.bottom - highlightBounds.top, viewportHeight ) - viewportHeight ) / 2;
+
+ // Account for offsets in position applied to the
+ // that holds our lines of code
+ var lineTable = block.querySelector( '.hljs-ln' );
+ if( lineTable ) targetTop += lineTable.offsetTop - parseInt( blockStyles.paddingTop );
+
+ // Make sure the scroll target is within bounds
+ targetTop = Math.max( Math.min( targetTop, block.scrollHeight - viewportHeight ), 0 );
+
+ if( skipAnimation === true || startTop === targetTop ) {
+ block.scrollTop = targetTop;
+ }
+ else {
+
+ // Don't attempt to scroll if there is no overflow
+ if( block.scrollHeight <= viewportHeight ) return;
+
+ var time = 0;
+ var animate = function() {
+ time = Math.min( time + 0.02, 1 );
+
+ // Update our eased scroll position
+ block.scrollTop = startTop + ( targetTop - startTop ) * Plugin.easeInOutQuart( time );
+
+ // Keep animating unless we've reached the end
+ if( time < 1 ) {
+ scrollState.animationFrameID = requestAnimationFrame( animate );
+ }
+ };
+
+ animate();
+
+ }
+
+ },
+
+ /**
+ * The easing function used when scrolling.
+ */
+ easeInOutQuart: function( t ) {
+
+ // easeInOutQuart
+ return t<.5 ? 8*t*t*t*t : 1-8*(--t)*t*t*t;
+
+ },
+
+ getHighlightedLineBounds: function( block ) {
+
+ var highlightedLines = block.querySelectorAll( '.highlight-line' );
+ if( highlightedLines.length === 0 ) {
+ return { top: 0, bottom: 0 };
+ }
+ else {
+ var firstHighlight = highlightedLines[0];
+ var lastHighlight = highlightedLines[ highlightedLines.length -1 ];
+
+ return {
+ top: firstHighlight.offsetTop,
+ bottom: lastHighlight.offsetTop + lastHighlight.offsetHeight
+ }
+ }
+
+ },
+
+ /**
+ * Visually emphasize specific lines within a code block.
+ * This only works on blocks with line numbering turned on.
+ *
+ * @param {HTMLElement} block a block
+ * @param {String} [linesToHighlight] The lines that should be
+ * highlighted in this format:
+ * "1" = highlights line 1
+ * "2,5" = highlights lines 2 & 5
+ * "2,5-7" = highlights lines 2, 5, 6 & 7
+ */
+ highlightLines: function( block, linesToHighlight ) {
+
+ var highlightSteps = Plugin.deserializeHighlightSteps( linesToHighlight || block.getAttribute( 'data-line-numbers' ) );
+
+ if( highlightSteps.length ) {
+
+ highlightSteps[0].forEach( function( highlight ) {
+
+ var elementsToHighlight = [];
+
+ // Highlight a range
+ if( typeof highlight.end === 'number' ) {
+ elementsToHighlight = [].slice.call( block.querySelectorAll( 'table tr:nth-child(n+'+highlight.start+'):nth-child(-n+'+highlight.end+')' ) );
+ }
+ // Highlight a single line
+ else if( typeof highlight.start === 'number' ) {
+ elementsToHighlight = [].slice.call( block.querySelectorAll( 'table tr:nth-child('+highlight.start+')' ) );
+ }
+
+ if( elementsToHighlight.length ) {
+ elementsToHighlight.forEach( function( lineElement ) {
+ lineElement.classList.add( 'highlight-line' );
+ } );
+
+ block.classList.add( 'has-highlights' );
+ }
+
+ } );
+
+ }
+
+ },
+
+ /**
+ * Parses and formats a user-defined string of line
+ * numbers to highlight.
+ *
+ * @example
+ * Plugin.deserializeHighlightSteps( '1,2|3,5-10' )
+ * // [
+ * // [ { start: 1 }, { start: 2 } ],
+ * // [ { start: 3 }, { start: 5, end: 10 } ]
+ * // ]
+ */
+ deserializeHighlightSteps: function( highlightSteps ) {
+
+ // Remove whitespace
+ highlightSteps = highlightSteps.replace( /\s/g, '' );
+
+ // Divide up our line number groups
+ highlightSteps = highlightSteps.split( Plugin.HIGHLIGHT_STEP_DELIMITER );
+
+ return highlightSteps.map( function( highlights ) {
+
+ return highlights.split( Plugin.HIGHLIGHT_LINE_DELIMITER ).map( function( highlight ) {
+
+ // Parse valid line numbers
+ if( /^[\d-]+$/.test( highlight ) ) {
+
+ highlight = highlight.split( Plugin.HIGHLIGHT_LINE_RANGE_DELIMITER );
+
+ var lineStart = parseInt( highlight[0], 10 ),
+ lineEnd = parseInt( highlight[1], 10 );
+
+ if( isNaN( lineEnd ) ) {
+ return {
+ start: lineStart
+ };
+ }
+ else {
+ return {
+ start: lineStart,
+ end: lineEnd
+ };
+ }
+
+ }
+ // If no line numbers are provided, no code will be highlighted
+ else {
+
+ return {};
+
+ }
+
+ } );
+
+ } );
+
+ },
+
+ /**
+ * Serializes parsed line number data into a string so
+ * that we can store it in the DOM.
+ */
+ serializeHighlightSteps: function( highlightSteps ) {
+
+ return highlightSteps.map( function( highlights ) {
+
+ return highlights.map( function( highlight ) {
+
+ // Line range
+ if( typeof highlight.end === 'number' ) {
+ return highlight.start + Plugin.HIGHLIGHT_LINE_RANGE_DELIMITER + highlight.end;
+ }
+ // Single line
+ else if( typeof highlight.start === 'number' ) {
+ return highlight.start;
+ }
+ // All lines
+ else {
+ return '';
+ }
+
+ } ).join( Plugin.HIGHLIGHT_LINE_DELIMITER );
+
+ } ).join( Plugin.HIGHLIGHT_STEP_DELIMITER );
+
+ }
+
+}
+
+// Function to perform a better "data-trim" on code snippets
+// Will slice an indentation amount on each line of the snippet (amount based on the line having the lowest indentation length)
+function betterTrim(snippetEl) {
+ // Helper functions
+ function trimLeft(val) {
+ // Adapted from https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/Trim#Polyfill
+ return val.replace(/^[\s\uFEFF\xA0]+/g, '');
+ }
+ function trimLineBreaks(input) {
+ var lines = input.split('\n');
+
+ // Trim line-breaks from the beginning
+ for (var i = 0; i < lines.length; i++) {
+ if (lines[i].trim() === '') {
+ lines.splice(i--, 1);
+ } else break;
+ }
+
+ // Trim line-breaks from the end
+ for (var i = lines.length-1; i >= 0; i--) {
+ if (lines[i].trim() === '') {
+ lines.splice(i, 1);
+ } else break;
+ }
+
+ return lines.join('\n');
+ }
+
+ // Main function for betterTrim()
+ return (function(snippetEl) {
+ var content = trimLineBreaks(snippetEl.innerHTML);
+ var lines = content.split('\n');
+ // Calculate the minimum amount to remove on each line start of the snippet (can be 0)
+ var pad = lines.reduce(function(acc, line) {
+ if (line.length > 0 && trimLeft(line).length > 0 && acc > line.length - trimLeft(line).length) {
+ return line.length - trimLeft(line).length;
+ }
+ return acc;
+ }, Number.POSITIVE_INFINITY);
+ // Slice each line with this amount
+ return lines.map(function(line, index) {
+ return line.slice(pad);
+ })
+ .join('\n');
+ })(snippetEl);
+}
+
+export default () => Plugin;