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80 lines
2.1 KiB
80 lines
2.1 KiB
module.exports = sortByProcedure;
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/*
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sort the parts of the passed selector,
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as there is potential for optimization
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(some types of selectors are faster than others)
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*/
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var procedure = require("./procedure.json");
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var attributes = {
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__proto__: null,
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exists: 10,
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equals: 8,
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not: 7,
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start: 6,
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end: 6,
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any: 5,
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hyphen: 4,
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element: 4
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};
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function sortByProcedure(arr) {
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var procs = arr.map(getProcedure);
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for (var i = 1; i < arr.length; i++) {
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var procNew = procs[i];
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if (procNew < 0) continue;
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for (var j = i - 1; j >= 0 && procNew < procs[j]; j--) {
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var token = arr[j + 1];
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arr[j + 1] = arr[j];
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arr[j] = token;
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procs[j + 1] = procs[j];
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procs[j] = procNew;
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}
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}
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}
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function getProcedure(token) {
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var proc = procedure[token.type];
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if (proc === procedure.attribute) {
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proc = attributes[token.action];
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if (proc === attributes.equals && token.name === "id") {
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//prefer ID selectors (eg. #ID)
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proc = 9;
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}
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if (token.ignoreCase) {
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//ignoreCase adds some overhead, prefer "normal" token
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//this is a binary operation, to ensure it's still an int
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proc >>= 1;
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}
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} else if (proc === procedure.pseudo) {
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if (!token.data) {
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proc = 3;
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} else if (token.name === "has" || token.name === "contains") {
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proc = 0; //expensive in any case
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} else if (token.name === "matches" || token.name === "not") {
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proc = 0;
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for (var i = 0; i < token.data.length; i++) {
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//TODO better handling of complex selectors
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if (token.data[i].length !== 1) continue;
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var cur = getProcedure(token.data[i][0]);
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//avoid executing :has or :contains
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if (cur === 0) {
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proc = 0;
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break;
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}
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if (cur > proc) proc = cur;
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}
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if (token.data.length > 1 && proc > 0) proc -= 1;
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} else {
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proc = 1;
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}
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}
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return proc;
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}
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