add collapse support

Author: Christopher Baker

index.js

@@ -1,32 +1,60 @@
 var $ = require("jquery");
 
-var getConfig = function(lineString) {
+var getConfig = function(lineString, lineCount) {
 	var lines = lineString
 		.split(',')
 		.map(function(data) {
 			return data.trim();
-		});
+		})
+		.filter(function(data) {
+			return data;
+		})
+	;
 
-	var only = false;
+	var collapse = [];
 	var index = lines.indexOf('only');
 	if (index > -1) {
-		only = true;
 		lines.splice(index, 1);
+
+		var current = 1;
+		for (var i = 0; i < lines.length; i++) {
+			var range = lines[i]
+				.split('-')
+				.map(function(val) {
+					return parseInt(val);
+				})
+				.filter(function(val) {
+					return typeof val === 'number' && !isNaN(val);
+				})
+			;
+
+			if (range[0] > current + padding) {
+				collapse.push(current + '-' + (range[0] - 1 - padding));
+			}
+
+			current = (range[1] || range[0]) + padding + 1;
+		}
+
+		if (current < lineCount) {
+			collapse.push(current + '-' + lineCount);
+		}
 	}
 
 	return {
-		lines: lines.join(','),
-		collapse: false,
+		lines: lines.length ? lines.join(',') : false,
+		collapse: collapse.length ? collapse.join(',') : false,
 	};
 };
 
 module.exports = function() {
 	$('span[line-highlight]').each(function(i, el) {
 		var $el = $(el);
-		var config = getConfig($el.attr('line-highlight'));
 		var preBlock = $el.parent().prev('pre');
 		var codeBlock = preBlock.children('code');
 
+		var total = codeBlock.text().split('\n').length - 1;
+		var config = getConfig($el.attr('line-highlight'), total);
+
 		if (preBlock) {
 			preBlock.attr('data-line', config.lines);