--- /dev/null
+"use strict";
+
+const _ = require("lodash");
+const isStandardSyntaxRule = require("../../utils/isStandardSyntaxRule");
+const isStandardSyntaxSelector = require("../../utils/isStandardSyntaxSelector");
+const keywordSets = require("../../reference/keywordSets");
+const optionsMatches = require("../../utils/optionsMatches");
+const parseSelector = require("../../utils/parseSelector");
+const postcss = require("postcss");
+const report = require("../../utils/report");
+const ruleMessages = require("../../utils/ruleMessages");
+const validateOptions = require("../../utils/validateOptions");
+
+const ruleName = "selector-pseudo-element-no-unknown";
+
+const messages = ruleMessages(ruleName, {
+ rejected: selector =>
+ `Unexpected unknown pseudo-element selector "${selector}"`
+});
+
+const rule = function(actual, options) {
+ return (root, result) => {
+ const validOptions = validateOptions(
+ result,
+ ruleName,
+ { actual },
+ {
+ actual: options,
+ possible: {
+ ignorePseudoElements: [_.isString]
+ },
+ optional: true
+ }
+ );
+ if (!validOptions) {
+ return;
+ }
+
+ root.walkRules(rule => {
+ if (!isStandardSyntaxRule(rule)) {
+ return;
+ }
+ const selector = rule.selector;
+
+ // Return early before parse if no pseudos for performance
+
+ if (selector.indexOf(":") === -1) {
+ return;
+ }
+
+ parseSelector(selector, result, rule, selectorTree => {
+ selectorTree.walkPseudos(pseudoNode => {
+ const value = pseudoNode.value;
+
+ if (!isStandardSyntaxSelector(value)) {
+ return;
+ }
+
+ // Ignore pseudo-classes
+ if (value.slice(0, 2) !== "::") {
+ return;
+ }
+
+ if (
+ optionsMatches(
+ options,
+ "ignorePseudoElements",
+ pseudoNode.value.slice(2)
+ )
+ ) {
+ return;
+ }
+
+ const name = value.slice(2);
+
+ if (
+ postcss.vendor.prefix(name) ||
+ keywordSets.pseudoElements.has(name.toLowerCase())
+ ) {
+ return;
+ }
+
+ report({
+ message: messages.rejected(value),
+ node: rule,
+ index: pseudoNode.sourceIndex,
+ ruleName,
+ result
+ });
+ });
+ });
+ });
+ };
+};
+
+rule.ruleName = ruleName;
+rule.messages = messages;
+module.exports = rule;