perf(parser): binary search for comments in range

Signed-off-by: Peter Somogyvari <peter.metz@unarin.com>

lib/javascript/JavascriptParser.js

@@ -10,6 +10,7 @@ const { SyncBailHook, HookMap } = require("tapable");
 const vm = require("vm");
 const Parser = require("../Parser");
 const StackedMap = require("../util/StackedMap");
+const binarySearchBounds = require("../util/binarySearchBounds");
 const memorize = require("../util/memorize");
 const BasicEvaluatedExpression = require("./BasicEvaluatedExpression");
 
@@ -3327,9 +3328,16 @@ class JavascriptParser extends Parser {
 	}
 
 	getComments(range) {
-		return this.comments.filter(
-			comment => comment.range[0] >= range[0] && comment.range[1] <= range[1]
-		);
+		const [rangeStart, rangeEnd] = range;
+		const compare = (comment, needle) => comment.range[0] - needle;
+		let idx = binarySearchBounds.ge(this.comments, rangeStart, compare);
+		let commentsInRange = [];
+		while (this.comments[idx] && this.comments[idx].range[1] <= rangeEnd) {
+			commentsInRange.push(this.comments[idx]);
+			idx++;
+		}
+
+		return commentsInRange;
 	}
 
 	/**

lib/util/binarySearchBounds.js

@@ -0,0 +1,86 @@
+/*
+	MIT License http://www.opensource.org/licenses/mit-license.php
+	Author Mikola Lysenko @mikolalysenko
+*/
+
+"use strict";
+
+/* cspell:disable-next-line */
+// Refactor: Peter Somogyvari @petermetz
+
+const compileSearch = (funcName, predicate, reversed, extraArgs, earlyOut) => {
+	const code = [
+		"function ",
+		funcName,
+		"(a,l,h,",
+		extraArgs.join(","),
+		"){",
+		earlyOut ? "" : "var i=",
+		reversed ? "l-1" : "h+1",
+		";while(l<=h){var m=(l+h)>>>1,x=a[m]"
+	];
+
+	if (earlyOut) {
+		if (predicate.indexOf("c") < 0) {
+			code.push(";if(x===y){return m}else if(x<=y){");
+		} else {
+			code.push(";var p=c(x,y);if(p===0){return m}else if(p<=0){");
+		}
+	} else {
+		code.push(";if(", predicate, "){i=m;");
+	}
+	if (reversed) {
+		code.push("l=m+1}else{h=m-1}");
+	} else {
+		code.push("h=m-1}else{l=m+1}");
+	}
+	code.push("}");
+	if (earlyOut) {
+		code.push("return -1};");
+	} else {
+		code.push("return i};");
+	}
+	return code.join("");
+};
+
+const compileBoundsSearch = (predicate, reversed, suffix, earlyOut) => {
+	const arg1 = compileSearch(
+		"A",
+		"x" + predicate + "y",
+		reversed,
+		["y"],
+		earlyOut
+	);
+
+	const arg2 = compileSearch(
+		"P",
+		"c(x,y)" + predicate + "0",
+		reversed,
+		["y", "c"],
+		earlyOut
+	);
+
+	const fnHeader = "function dispatchBinarySearch";
+
+	const fnBody =
+		"(a,y,c,l,h){\
+if(typeof(c)==='function'){\
+return P(a,(l===void 0)?0:l|0,(h===void 0)?a.length-1:h|0,y,c)\
+}else{\
+return A(a,(c===void 0)?0:c|0,(l===void 0)?a.length-1:l|0,y)\
+}}\
+return dispatchBinarySearch";
+
+	const fnArgList = [arg1, arg2, fnHeader, suffix, fnBody, suffix];
+	const fnSource = fnArgList.join("");
+	const result = new Function(fnSource);
+	return result();
+};
+
+module.exports = {
+	ge: compileBoundsSearch(">=", false, "GE"),
+	gt: compileBoundsSearch(">", false, "GT"),
+	lt: compileBoundsSearch("<", true, "LT"),
+	le: compileBoundsSearch("<=", true, "LE"),
+	eq: compileBoundsSearch("-", true, "EQ", true)
+};

types.d.ts

@@ -4319,7 +4319,7 @@ declare class JavascriptParser extends Parser {
 		commentsStartPos: number,
 		args?: any
 	): boolean;
-	getComments(range?: any): any;
+	getComments(range?: any): any[];
 	isAsiPosition(pos: number): boolean;
 	isStatementLevelExpression(expr?: any): boolean;
 	getTagData(name?: any, tag?: any): any;