update elements and fix some bugs

lib/src/prism/plugins/previewer-gradient/prism-previewer-gradient.js

Index: lib/src/prism/plugins/previewer-gradient/prism-previewer-gradient.js
diff --git a/lib/src/prism/plugins/previewer-gradient/prism-previewer-gradient.js b/lib/src/prism/plugins/previewer-gradient/prism-previewer-gradient.js
new file mode 100644
index 0000000000000000000000000000000000000000..11c2d0619e4ade3bde93ce094c81a8b4a0372f78
--- /dev/null
+++ b/lib/src/prism/plugins/previewer-gradient/prism-previewer-gradient.js
@@ -0,0 +1,216 @@
+(function() {
+
+	if (
+		typeof self !== 'undefined' && !self.Prism ||
+		typeof global !== 'undefined' && !global.Prism
+	) {
+		return;
+	}
+
+	var languages = {
+		'css': true,
+		'less': true,
+		'sass': [
+			{
+				lang: 'sass',
+				before: 'punctuation',
+				inside: 'inside',
+				root: Prism.languages.sass && Prism.languages.sass['variable-line']
+			},
+			{
+				lang: 'sass',
+				before: 'punctuation',
+				inside: 'inside',
+				root: Prism.languages.sass && Prism.languages.sass['property-line']
+			}
+		],
+		'scss': true,
+		'stylus': [
+			{
+				lang: 'stylus',
+				before: 'func',
+				inside: 'rest',
+				root: Prism.languages.stylus && Prism.languages.stylus['property-declaration'].inside
+			},
+			{
+				lang: 'stylus',
+				before: 'func',
+				inside: 'rest',
+				root: Prism.languages.stylus && Prism.languages.stylus['variable-declaration'].inside
+			}
+		]
+	};
+
+	Prism.hooks.add('before-highlight', function (env) {
+		if (env.language && languages[env.language] && !languages[env.language].initialized) {
+			var lang = languages[env.language];
+			if (Prism.util.type(lang) !== 'Array') {
+				lang = [lang];
+			}
+			lang.forEach(function(lang) {
+				var before, inside, root, skip;
+				if (lang === true) {
+					// Insert before color previewer if it exists
+					before = Prism.plugins.Previewer && Prism.plugins.Previewer.byType['color'] ? 'color' : 'important';
+					inside = env.language;
+					lang = env.language;
+				} else {
+					before = lang.before || 'important';
+					inside = lang.inside || lang.lang;
+					root = lang.root || Prism.languages;
+					skip = lang.skip;
+					lang = env.language;
+				}
+
+				if (!skip && Prism.languages[lang]) {
+					Prism.languages.insertBefore(inside, before, {
+						'gradient': {
+							pattern: /(?:\b|\B-[a-z]{1,10}-)(?:repeating-)?(?:linear|radial)-gradient\((?:(?:rgb|hsl)a?\(.+?\)|[^\)])+\)/gi,
+							inside: {
+								'function': /[\w-]+(?=\()/,
+								'punctuation': /[(),]/
+							}
+						}
+					}, root);
+					env.grammar = Prism.languages[lang];
+
+					languages[env.language] = {initialized: true};
+				}
+			});
+		}
+	});
+
+	// Stores already processed gradients so that we don't
+	// make the conversion every time the previewer is shown
+	var cache = {};
+
+	/**
+	 * Returns a W3C-valid linear gradient
+	 * @param {string} prefix Vendor prefix if any ("-moz-", "-webkit-", etc.)
+	 * @param {string} func Gradient function name ("linear-gradient")
+	 * @param {string[]} values Array of the gradient function parameters (["0deg", "red 0%", "blue 100%"])
+	 */
+	var convertToW3CLinearGradient = function(prefix, func, values) {
+		// Default value for angle
+		var angle = '180deg';
+
+		if (/^(?:-?\d*\.?\d+(?:deg|rad)|to\b|top|right|bottom|left)/.test(values[0])) {
+			angle = values.shift();
+			if (angle.indexOf('to ') < 0) {
+				// Angle uses old keywords
+				// W3C syntax uses "to" + opposite keywords
+				if (angle.indexOf('top') >= 0) {
+					if (angle.indexOf('left') >= 0) {
+						angle = 'to bottom right';
+					} else if (angle.indexOf('right') >= 0) {
+						angle = 'to bottom left';
+					} else {
+						angle = 'to bottom';
+					}
+				} else if (angle.indexOf('bottom') >= 0) {
+					if (angle.indexOf('left') >= 0) {
+						angle = 'to top right';
+					} else if (angle.indexOf('right') >= 0) {
+						angle = 'to top left';
+					} else {
+						angle = 'to top';
+					}
+				} else if (angle.indexOf('left') >= 0) {
+					angle = 'to right';
+				} else if (angle.indexOf('right') >= 0) {
+					angle = 'to left';
+				} else if (prefix) {
+					// Angle is shifted by 90deg in prefixed gradients
+					if (angle.indexOf('deg') >= 0) {
+						angle = (90 - parseFloat(angle)) + 'deg';
+					} else if (angle.indexOf('rad') >= 0) {
+						angle = (Math.PI / 2 - parseFloat(angle)) + 'rad';
+					}
+				}
+			}
+		}
+
+		return func + '(' + angle + ',' + values.join(',') + ')';
+	};
+
+	/**
+	 * Returns a W3C-valid radial gradient
+	 * @param {string} prefix Vendor prefix if any ("-moz-", "-webkit-", etc.)
+	 * @param {string} func Gradient function name ("linear-gradient")
+	 * @param {string[]} values Array of the gradient function parameters (["0deg", "red 0%", "blue 100%"])
+	 */
+	var convertToW3CRadialGradient = function(prefix, func, values) {
+		if (values[0].indexOf('at') < 0) {
+			// Looks like old syntax
+
+			// Default values
+			var position = 'center';
+			var shape = 'ellipse';
+			var size = 'farthest-corner';
+
+			if (/\bcenter|top|right|bottom|left\b|^\d+/.test(values[0])) {
+				// Found a position
+				// Remove angle value, if any
+				position = values.shift().replace(/\s*-?\d+(?:rad|deg)\s*/, '');
+			}
+			if (/\bcircle|ellipse|closest|farthest|contain|cover\b/.test(values[0])) {
+				// Found a shape and/or size
+				var shapeSizeParts = values.shift().split(/\s+/);
+				if (shapeSizeParts[0] && (shapeSizeParts[0] === 'circle' || shapeSizeParts[0] === 'ellipse')) {
+					shape = shapeSizeParts.shift();
+				}
+				if (shapeSizeParts[0]) {
+					size = shapeSizeParts.shift();
+				}
+
+				// Old keywords are converted to their synonyms
+				if (size === 'cover') {
+					size = 'farthest-corner';
+				} else if (size === 'contain') {
+					size = 'clothest-side';
+				}
+			}
+
+			return func + '(' + shape + ' ' + size + ' at ' + position + ',' + values.join(',') + ')';
+		}
+		return func + '(' + values.join(',') + ')';
+	};
+
+	/**
+	 * Converts a gradient to a W3C-valid one
+	 * Does not support old webkit syntax (-webkit-gradient(linear...) and -webkit-gradient(radial...))
+	 * @param {string} gradient The CSS gradient
+	 */
+	var convertToW3CGradient = function(gradient) {
+		if (cache[gradient]) {
+			return cache[gradient];
+		}
+		var parts = gradient.match(/^(\b|\B-[a-z]{1,10}-)((?:repeating-)?(?:linear|radial)-gradient)/);
+		// "", "-moz-", etc.
+		var prefix = parts && parts[1];
+		// "linear-gradient", "radial-gradient", etc.
+		var func = parts && parts[2];
+
+		var values = gradient.replace(/^(?:\b|\B-[a-z]{1,10}-)(?:repeating-)?(?:linear|radial)-gradient\(|\)$/g, '').split(/\s*,\s*/);
+
+		if (func.indexOf('linear') >= 0) {
+			return cache[gradient] = convertToW3CLinearGradient(prefix, func, values);
+		} else if (func.indexOf('radial') >= 0) {
+			return cache[gradient] = convertToW3CRadialGradient(prefix, func, values);
+		}
+		return cache[gradient] = func + '(' + values.join(',') + ')';
+	};
+
+
+
+	if (Prism.plugins.Previewer) {
+		new Prism.plugins.Previewer('gradient', function(value) {
+			this.firstChild.style.backgroundImage = '';
+			this.firstChild.style.backgroundImage = convertToW3CGradient(value);
+			return !!this.firstChild.style.backgroundImage;
+		}, '*', function () {
+			this._elt.innerHTML = '<div></div>';
+		});
+	}
+
+}());