ultraviolet/rewrite/parsel.js
2022-02-14 00:25:17 -05:00

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export default (function (exports) {
'use strict';
const TOKENS = {
attribute: /\[\s*(?:(?<namespace>\*|[-\w]*)\|)?(?<name>[-\w\u{0080}-\u{FFFF}]+)\s*(?:(?<operator>\W?=)\s*(?<value>.+?)\s*(?<caseSensitive>[iIsS])?\s*)?\]/gu,
id: /#(?<name>(?:[-\w\u{0080}-\u{FFFF}]|\\.)+)/gu,
class: /\.(?<name>(?:[-\w\u{0080}-\u{FFFF}]|\\.)+)/gu,
comma: /\s*,\s*/g, // must be before combinator
combinator: /\s*[\s>+~]\s*/g, // this must be after attribute
"pseudo-element": /::(?<name>[-\w\u{0080}-\u{FFFF}]+)(?:\((?<argument>¶+)\))?/gu, // this must be before pseudo-class
"pseudo-class": /:(?<name>[-\w\u{0080}-\u{FFFF}]+)(?:\((?<argument>¶+)\))?/gu,
type: /(?:(?<namespace>\*|[-\w]*)\|)?(?<name>[-\w\u{0080}-\u{FFFF}]+)|\*/gu // this must be last
};
const TOKENS_WITH_PARENS = new Set(["pseudo-class", "pseudo-element"]);
const TOKENS_WITH_STRINGS = new Set([...TOKENS_WITH_PARENS, "attribute"]);
const TRIM_TOKENS = new Set(["combinator", "comma"]);
const RECURSIVE_PSEUDO_CLASSES = new Set(["not", "is", "where", "has", "matches", "-moz-any", "-webkit-any", "nth-child", "nth-last-child"]);
const RECURSIVE_PSEUDO_CLASSES_ARGS = {
"nth-child": /(?<index>[\dn+-]+)\s+of\s+(?<subtree>.+)/
};
RECURSIVE_PSEUDO_CLASSES["nth-last-child"] = RECURSIVE_PSEUDO_CLASSES_ARGS["nth-child"];
const TOKENS_FOR_RESTORE = Object.assign({}, TOKENS);
TOKENS_FOR_RESTORE["pseudo-element"] = RegExp(TOKENS["pseudo-element"].source.replace("(?<argument>¶+)", "(?<argument>.+?)"), "gu");
TOKENS_FOR_RESTORE["pseudo-class"] = RegExp(TOKENS["pseudo-class"].source.replace("(?<argument>¶+)", "(?<argument>.+)"), "gu");
function gobbleParens(text, i) {
let str = "", stack = [];
for (; i < text.length; i++) {
let char = text[i];
if (char === "(") {
stack.push(char);
}
else if (char === ")") {
if (stack.length > 0) {
stack.pop();
}
else {
throw new Error("Closing paren without opening paren at " + i);
}
}
str += char;
if (stack.length === 0) {
return str;
}
}
throw new Error("Opening paren without closing paren");
}
function tokenizeBy (text, grammar) {
if (!text) {
return [];
}
var strarr = [text];
for (var token in grammar) {
let pattern = grammar[token];
for (var i=0; i < strarr.length; i++) { // Dont cache length as it changes during the loop
var str = strarr[i];
if (typeof str === "string") {
pattern.lastIndex = 0;
var match = pattern.exec(str);
if (match) {
let from = match.index - 1;
let args = [];
let content = match[0];
let before = str.slice(0, from + 1);
if (before) {
args.push(before);
}
args.push({
type: token,
content,
...match.groups
});
let after = str.slice(from + content.length + 1);
if (after) {
args.push(after);
}
strarr.splice(i, 1, ...args);
}
}
}
}
let offset = 0;
for (let i=0; i<strarr.length; i++) {
let token = strarr[i];
let length = token.length || token.content.length;
if (typeof token === "object") {
token.pos = [offset, offset + length];
if (TRIM_TOKENS.has(token.type)) {
token.content = token.content.trim() || " ";
}
}
offset += length;
}
return strarr;
}
function tokenize (selector) {
if (!selector) {
return null;
}
selector = selector.trim(); // prevent leading/trailing whitespace be interpreted as combinators
// Replace strings with whitespace strings (to preserve offsets)
let strings = [];
// FIXME Does not account for escaped backslashes before a quote
selector = selector.replace(/(['"])(\\\1|.)+?\1/g, (str, quote, content, start) => {
strings.push({str, start});
return quote + "§".repeat(content.length) + quote;
});
// Now that strings are out of the way, extract parens and replace them with parens with whitespace (to preserve offsets)
let parens = [], offset = 0, start;
while ((start = selector.indexOf("(", offset)) > -1) {
let str = gobbleParens(selector, start);
parens.push({str, start});
selector = selector.substring(0, start) + "(" + "¶".repeat(str.length - 2) + ")" + selector.substring(start + str.length);
offset = start + str.length;
}
// Now we have no nested structures and we can parse with regexes
let tokens = tokenizeBy(selector, TOKENS);
// Now restore parens and strings in reverse order
function restoreNested(strings, regex, types) {
for (let str of strings) {
for (let token of tokens) {
if (types.has(token.type) && token.pos[0] < str.start && str.start < token.pos[1]) {
let content = token.content;
token.content = token.content.replace(regex, str.str);
if (token.content !== content) { // actually changed?
// Re-evaluate groups
TOKENS_FOR_RESTORE[token.type].lastIndex = 0;
let match = TOKENS_FOR_RESTORE[token.type].exec(token.content);
let groups = match.groups;
Object.assign(token, groups);
}
}
}
}
}
restoreNested(parens, /\(¶+\)/, TOKENS_WITH_PARENS);
restoreNested(strings, /(['"])§+?\1/, TOKENS_WITH_STRINGS);
return tokens;
}
// Convert a flat list of tokens into a tree of complex & compound selectors
function nestTokens(tokens, {list = true} = {}) {
if (list && tokens.find(t => t.type === "comma")) {
let selectors = [], temp = [];
for (let i=0; i<tokens.length; i++) {
if (tokens[i].type === "comma") {
if (temp.length === 0) {
throw new Error("Incorrect comma at " + i);
}
selectors.push(nestTokens(temp, {list: false}));
temp.length = 0;
}
else {
temp.push(tokens[i]);
}
}
if (temp.length === 0) {
throw new Error("Trailing comma");
}
else {
selectors.push(nestTokens(temp, {list: false}));
}
return { type: "list", list: selectors };
}
for (let i=tokens.length - 1; i>=0; i--) {
let token = tokens[i];
if (token.type === "combinator") {
let left = tokens.slice(0, i);
let right = tokens.slice(i + 1);
return {
type: "complex",
combinator: token.content,
left: nestTokens(left),
right: nestTokens(right)
};
}
}
if (tokens.length === 0) {
return null;
}
// If we're here, there are no combinators, so it's just a list
return tokens.length === 1? tokens[0] : {
type: "compound",
list: [...tokens] // clone to avoid pointers messing up the AST
};
}
// Traverse an AST (or part thereof), in depth-first order
function walk(node, callback, o, parent) {
if (!node) {
return;
}
if (node.type === "complex") {
walk(node.left, callback, o, node);
walk(node.right, callback, o, node);
}
else if (node.type === "compound") {
for (let n of node.list) {
walk(n, callback, o, node);
}
}
else if (node.subtree && o && o.subtree) {
walk(node.subtree, callback, o, node);
}
callback(node, parent);
}
/**
* Parse a CSS selector
* @param selector {String} The selector to parse
* @param options.recursive {Boolean} Whether to parse the arguments of pseudo-classes like :is(), :has() etc. Defaults to true.
* @param options.list {Boolean} Whether this can be a selector list (A, B, C etc). Defaults to true.
*/
function parse(selector, {recursive = true, list = true} = {}) {
let tokens = tokenize(selector);
if (!tokens) {
return null;
}
let ast = nestTokens(tokens, {list});
if (recursive) {
walk(ast, node => {
if (node.type === "pseudo-class" && node.argument) {
if (RECURSIVE_PSEUDO_CLASSES.has(node.name)) {
let argument = node.argument;
const childArg = RECURSIVE_PSEUDO_CLASSES_ARGS[node.name];
if (childArg) {
const match = childArg.exec(argument);
if (!match) {
return;
}
Object.assign(node, match.groups);
argument = match.groups.subtree;
}
if (argument) {
node.subtree = parse(argument, {recursive: true, list: true});
}
}
}
});
}
return ast;
}
function specificityToNumber(specificity, base) {
base = base || Math.max(...specificity) + 1;
return specificity[0] * base ** 2 + specificity[1] * base + specificity[2];
}
function maxIndexOf(arr) {
let max = arr[0], ret = 0;
for (let i=0; i<arr.length; i++) {
if (arr[i] > max) {
ret = i;
max = arr[i];
}
}
return arr.length === 0? -1 : ret;
}
/**
* Calculate specificity of a selector.
* If the selector is a list, the max specificity is returned.
*/
function specificity(selector, {format = "array"} = {}) {
let ast = typeof selector === "object"? selector : parse(selector, {recursive: true});
if (!ast) {
return null;
}
if (ast.type === "list") {
// Return max specificity
let base = 10;
let specificities = ast.list.map(s => {
let sp = specificity(s);
base = Math.max(base, ...sp);
return sp;
});
let numbers = specificities.map(s => specificityToNumber(s, base));
let i = maxIndexOf(numbers);
return specificities[i];
}
let ret = [0, 0, 0];
walk(ast, node => {
if (node.type === "id") {
ret[0]++;
}
else if (node.type === "class" || node.type === "attribute") {
ret[1]++;
}
else if ((node.type === "type" && node.content !== "*") || node.type === "pseudo-element") {
ret[2]++;
}
else if (node.type === "pseudo-class" && node.name !== "where") {
if (RECURSIVE_PSEUDO_CLASSES.has(node.name) && node.subtree) {
// Max of argument list
let sub = specificity(node.subtree);
sub.forEach((s, i) => ret[i] += s);
}
else {
ret[1]++;
}
}
});
return ret;
}
exports.RECURSIVE_PSEUDO_CLASSES = RECURSIVE_PSEUDO_CLASSES;
exports.RECURSIVE_PSEUDO_CLASSES_ARGS = RECURSIVE_PSEUDO_CLASSES_ARGS;
exports.TOKENS = TOKENS;
exports.TRIM_TOKENS = TRIM_TOKENS;
exports.gobbleParens = gobbleParens;
exports.nestTokens = nestTokens;
exports.parse = parse;
exports.specificity = specificity;
exports.specificityToNumber = specificityToNumber;
exports.tokenize = tokenize;
exports.tokenizeBy = tokenizeBy;
exports.walk = walk;
Object.defineProperty(exports, '__esModule', { value: true });
return exports;
}({}));