08-27-周三_17-09-29

node_modules/css-select/lib/sort.js

@@ -0,0 +1,80 @@
+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;
+}