hexo/node_modules/css-select/lib/sort.js

module.exports = sortByProcedure;

/*
	sort the parts of the passed selector,
	as there is potential for optimization
	(some types of selectors are faster than others)
*/

var procedure = require("./procedure.json");

var attributes = {
	__proto__: null,
	exists: 10,
	equals: 8,
	not: 7,
	start: 6,
	end: 6,
	any: 5,
	hyphen: 4,
	element: 4
};

function sortByProcedure(arr){
	var procs = arr.map(getProcedure);
	for(var i = 1; i < arr.length; i++){
		var procNew = procs[i];

		if(procNew < 0) continue;

		for(var j = i - 1; j >= 0 && procNew < procs[j]; j--){
			var token = arr[j + 1];
			arr[j + 1] = arr[j];
			arr[j] = token;
			procs[j + 1] = procs[j];
			procs[j] = procNew;
		}
	}
}

function getProcedure(token){
	var proc = procedure[token.type];

	if(proc === procedure.attribute){
		proc = attributes[token.action];

		if(proc === attributes.equals && token.name === "id"){
			//prefer ID selectors (eg. #ID)
			proc = 9;
		}

		if(token.ignoreCase){
			//ignoreCase adds some overhead, prefer "normal" token
			//this is a binary operation, to ensure it's still an int
			proc >>= 1;
		}
	} else if(proc === procedure.pseudo){
		if(!token.data){
			proc = 3;
		} else if(token.name === "has" || token.name === "contains"){
			proc = 0; //expensive in any case
		} else if(token.name === "matches" || token.name === "not"){
			proc = 0;
			for(var i = 0; i < token.data.length; i++){
				//TODO better handling of complex selectors
				if(token.data[i].length !== 1) continue;
				var cur = getProcedure(token.data[i][0]);
				//avoid executing :has or :contains
				if(cur === 0){
					proc = 0;
					break;
				}
				if(cur > proc) proc = cur;
			}
			if(token.data.length > 1 && proc > 0) proc -= 1;
		} else {
			proc = 1;
		}
	}
	return proc;
}