--- /dev/null
+/**
+ * @fileoverview The event generator for AST nodes.
+ * @author Toru Nagashima
+ */
+
+"use strict";
+
+//------------------------------------------------------------------------------
+// Requirements
+//------------------------------------------------------------------------------
+
+const esquery = require("esquery");
+const lodash = require("lodash");
+
+//------------------------------------------------------------------------------
+// Typedefs
+//------------------------------------------------------------------------------
+
+/**
+ * An object describing an AST selector
+ * @typedef {Object} ASTSelector
+ * @property {string} rawSelector The string that was parsed into this selector
+ * @property {boolean} isExit `true` if this should be emitted when exiting the node rather than when entering
+ * @property {Object} parsedSelector An object (from esquery) describing the matching behavior of the selector
+ * @property {string[]|null} listenerTypes A list of node types that could possibly cause the selector to match,
+ * or `null` if all node types could cause a match
+ * @property {number} attributeCount The total number of classes, pseudo-classes, and attribute queries in this selector
+ * @property {number} identifierCount The total number of identifier queries in this selector
+ */
+
+//------------------------------------------------------------------------------
+// Helpers
+//------------------------------------------------------------------------------
+
+/**
+ * Gets the possible types of a selector
+ * @param {Object} parsedSelector An object (from esquery) describing the matching behavior of the selector
+ * @returns {string[]|null} The node types that could possibly trigger this selector, or `null` if all node types could trigger it
+ */
+function getPossibleTypes(parsedSelector) {
+ switch (parsedSelector.type) {
+ case "identifier":
+ return [parsedSelector.value];
+
+ case "matches": {
+ const typesForComponents = parsedSelector.selectors.map(getPossibleTypes);
+
+ if (typesForComponents.every(Boolean)) {
+ return lodash.union(...typesForComponents);
+ }
+ return null;
+ }
+
+ case "compound": {
+ const typesForComponents = parsedSelector.selectors.map(getPossibleTypes).filter(typesForComponent => typesForComponent);
+
+ // If all of the components could match any type, then the compound could also match any type.
+ if (!typesForComponents.length) {
+ return null;
+ }
+
+ /*
+ * If at least one of the components could only match a particular type, the compound could only match
+ * the intersection of those types.
+ */
+ return lodash.intersection(...typesForComponents);
+ }
+
+ case "child":
+ case "descendant":
+ case "sibling":
+ case "adjacent":
+ return getPossibleTypes(parsedSelector.right);
+
+ default:
+ return null;
+
+ }
+}
+
+/**
+ * Counts the number of class, pseudo-class, and attribute queries in this selector
+ * @param {Object} parsedSelector An object (from esquery) describing the selector's matching behavior
+ * @returns {number} The number of class, pseudo-class, and attribute queries in this selector
+ */
+function countClassAttributes(parsedSelector) {
+ switch (parsedSelector.type) {
+ case "child":
+ case "descendant":
+ case "sibling":
+ case "adjacent":
+ return countClassAttributes(parsedSelector.left) + countClassAttributes(parsedSelector.right);
+
+ case "compound":
+ case "not":
+ case "matches":
+ return parsedSelector.selectors.reduce((sum, childSelector) => sum + countClassAttributes(childSelector), 0);
+
+ case "attribute":
+ case "field":
+ case "nth-child":
+ case "nth-last-child":
+ return 1;
+
+ default:
+ return 0;
+ }
+}
+
+/**
+ * Counts the number of identifier queries in this selector
+ * @param {Object} parsedSelector An object (from esquery) describing the selector's matching behavior
+ * @returns {number} The number of identifier queries
+ */
+function countIdentifiers(parsedSelector) {
+ switch (parsedSelector.type) {
+ case "child":
+ case "descendant":
+ case "sibling":
+ case "adjacent":
+ return countIdentifiers(parsedSelector.left) + countIdentifiers(parsedSelector.right);
+
+ case "compound":
+ case "not":
+ case "matches":
+ return parsedSelector.selectors.reduce((sum, childSelector) => sum + countIdentifiers(childSelector), 0);
+
+ case "identifier":
+ return 1;
+
+ default:
+ return 0;
+ }
+}
+
+/**
+ * Compares the specificity of two selector objects, with CSS-like rules.
+ * @param {ASTSelector} selectorA An AST selector descriptor
+ * @param {ASTSelector} selectorB Another AST selector descriptor
+ * @returns {number}
+ * a value less than 0 if selectorA is less specific than selectorB
+ * a value greater than 0 if selectorA is more specific than selectorB
+ * a value less than 0 if selectorA and selectorB have the same specificity, and selectorA <= selectorB alphabetically
+ * a value greater than 0 if selectorA and selectorB have the same specificity, and selectorA > selectorB alphabetically
+ */
+function compareSpecificity(selectorA, selectorB) {
+ return selectorA.attributeCount - selectorB.attributeCount ||
+ selectorA.identifierCount - selectorB.identifierCount ||
+ (selectorA.rawSelector <= selectorB.rawSelector ? -1 : 1);
+}
+
+/**
+ * Parses a raw selector string, and throws a useful error if parsing fails.
+ * @param {string} rawSelector A raw AST selector
+ * @returns {Object} An object (from esquery) describing the matching behavior of this selector
+ * @throws {Error} An error if the selector is invalid
+ */
+function tryParseSelector(rawSelector) {
+ try {
+ return esquery.parse(rawSelector.replace(/:exit$/u, ""));
+ } catch (err) {
+ if (typeof err.offset === "number") {
+ throw new SyntaxError(`Syntax error in selector "${rawSelector}" at position ${err.offset}: ${err.message}`);
+ }
+ throw err;
+ }
+}
+
+/**
+ * Parses a raw selector string, and returns the parsed selector along with specificity and type information.
+ * @param {string} rawSelector A raw AST selector
+ * @returns {ASTSelector} A selector descriptor
+ */
+const parseSelector = lodash.memoize(rawSelector => {
+ const parsedSelector = tryParseSelector(rawSelector);
+
+ return {
+ rawSelector,
+ isExit: rawSelector.endsWith(":exit"),
+ parsedSelector,
+ listenerTypes: getPossibleTypes(parsedSelector),
+ attributeCount: countClassAttributes(parsedSelector),
+ identifierCount: countIdentifiers(parsedSelector)
+ };
+});
+
+//------------------------------------------------------------------------------
+// Public Interface
+//------------------------------------------------------------------------------
+
+/**
+ * The event generator for AST nodes.
+ * This implements below interface.
+ *
+ * ```ts
+ * interface EventGenerator {
+ * emitter: SafeEmitter;
+ * enterNode(node: ASTNode): void;
+ * leaveNode(node: ASTNode): void;
+ * }
+ * ```
+ */
+class NodeEventGenerator {
+
+ // eslint-disable-next-line jsdoc/require-description
+ /**
+ * @param {SafeEmitter} emitter
+ * An SafeEmitter which is the destination of events. This emitter must already
+ * have registered listeners for all of the events that it needs to listen for.
+ * (See lib/linter/safe-emitter.js for more details on `SafeEmitter`.)
+ * @returns {NodeEventGenerator} new instance
+ */
+ constructor(emitter) {
+ this.emitter = emitter;
+ this.currentAncestry = [];
+ this.enterSelectorsByNodeType = new Map();
+ this.exitSelectorsByNodeType = new Map();
+ this.anyTypeEnterSelectors = [];
+ this.anyTypeExitSelectors = [];
+
+ emitter.eventNames().forEach(rawSelector => {
+ const selector = parseSelector(rawSelector);
+
+ if (selector.listenerTypes) {
+ const typeMap = selector.isExit ? this.exitSelectorsByNodeType : this.enterSelectorsByNodeType;
+
+ selector.listenerTypes.forEach(nodeType => {
+ if (!typeMap.has(nodeType)) {
+ typeMap.set(nodeType, []);
+ }
+ typeMap.get(nodeType).push(selector);
+ });
+ return;
+ }
+ const selectors = selector.isExit ? this.anyTypeExitSelectors : this.anyTypeEnterSelectors;
+
+ selectors.push(selector);
+ });
+
+ this.anyTypeEnterSelectors.sort(compareSpecificity);
+ this.anyTypeExitSelectors.sort(compareSpecificity);
+ this.enterSelectorsByNodeType.forEach(selectorList => selectorList.sort(compareSpecificity));
+ this.exitSelectorsByNodeType.forEach(selectorList => selectorList.sort(compareSpecificity));
+ }
+
+ /**
+ * Checks a selector against a node, and emits it if it matches
+ * @param {ASTNode} node The node to check
+ * @param {ASTSelector} selector An AST selector descriptor
+ * @returns {void}
+ */
+ applySelector(node, selector) {
+ if (esquery.matches(node, selector.parsedSelector, this.currentAncestry)) {
+ this.emitter.emit(selector.rawSelector, node);
+ }
+ }
+
+ /**
+ * Applies all appropriate selectors to a node, in specificity order
+ * @param {ASTNode} node The node to check
+ * @param {boolean} isExit `false` if the node is currently being entered, `true` if it's currently being exited
+ * @returns {void}
+ */
+ applySelectors(node, isExit) {
+ const selectorsByNodeType = (isExit ? this.exitSelectorsByNodeType : this.enterSelectorsByNodeType).get(node.type) || [];
+ const anyTypeSelectors = isExit ? this.anyTypeExitSelectors : this.anyTypeEnterSelectors;
+
+ /*
+ * selectorsByNodeType and anyTypeSelectors were already sorted by specificity in the constructor.
+ * Iterate through each of them, applying selectors in the right order.
+ */
+ let selectorsByTypeIndex = 0;
+ let anyTypeSelectorsIndex = 0;
+
+ while (selectorsByTypeIndex < selectorsByNodeType.length || anyTypeSelectorsIndex < anyTypeSelectors.length) {
+ if (
+ selectorsByTypeIndex >= selectorsByNodeType.length ||
+ anyTypeSelectorsIndex < anyTypeSelectors.length &&
+ compareSpecificity(anyTypeSelectors[anyTypeSelectorsIndex], selectorsByNodeType[selectorsByTypeIndex]) < 0
+ ) {
+ this.applySelector(node, anyTypeSelectors[anyTypeSelectorsIndex++]);
+ } else {
+ this.applySelector(node, selectorsByNodeType[selectorsByTypeIndex++]);
+ }
+ }
+ }
+
+ /**
+ * Emits an event of entering AST node.
+ * @param {ASTNode} node A node which was entered.
+ * @returns {void}
+ */
+ enterNode(node) {
+ if (node.parent) {
+ this.currentAncestry.unshift(node.parent);
+ }
+ this.applySelectors(node, false);
+ }
+
+ /**
+ * Emits an event of leaving AST node.
+ * @param {ASTNode} node A node which was left.
+ * @returns {void}
+ */
+ leaveNode(node) {
+ this.applySelectors(node, true);
+ this.currentAncestry.shift();
+ }
+}
+
+module.exports = NodeEventGenerator;
projects / dotfiles / .git / blobdiff