Merge pull request #32 from webpack/performance/improvements

Performance improvements

lib/ConcatSource.js

@@ -11,27 +11,45 @@ const Source = require("./Source");
 class ConcatSource extends Source {
 	constructor() {
 		super();
-		this.children = Array.prototype.slice.call(arguments);
+		this.children = [];
+		for(var i = 0; i < arguments.length; i++) {
+			var item = arguments[i];
+			if(item instanceof ConcatSource) {
+				var children = item.children;
+				for(var j = 0; j < children.length; j++)
+					this.children.push(children[j]);
+			} else {
+				this.children.push(item);
+			}
+		}
 	}
 
 	add(item) {
-		this.children.push(item);
+		if(item instanceof ConcatSource) {
+			var children = item.children;
+			for(var j = 0; j < children.length; j++)
+				this.children.push(children[j]);
+		} else {
+			this.children.push(item);
+		}
 	}
 
 	source() {
 		let source = "";
-		for(let i = 0, len = this.children.length; i < len; ++i) {
-			const child = this.children[i];
-			source += (typeof child === "string") ? child : child.source();
+		const children = this.children;
+		for(let i = 0; i < children.length; i++) {
+			const child = children[i];
+			source += typeof child === "string" ? child : child.source();
 		}
 		return source;
 	}
 
 	size() {
 		let size = 0;
-		for(let i = 0, len = this.children.length; i < len; ++i) {
-			const child = this.children[i];
-			size += (typeof child === "string") ? child.length : child.size();
+		const children = this.children;
+		for(let i = 0; i < children.length; i++) {
+			const child = children[i];
+			size += typeof child === "string" ? child.length : child.size();
 		}
 		return size;
 	}
@@ -45,22 +63,26 @@ class ConcatSource extends Source {
 
 	listMap(options) {
 		const map = new SourceListMap();
-		this.children.forEach(function(item) {
+		var children = this.children;
+		for(var i = 0; i < children.length; i++) {
+			var item = children[i];
 			if(typeof item === "string")
 				map.add(item);
 			else
 				map.add(item.listMap(options));
-		});
+		}
 		return map;
 	}
 
 	updateHash(hash) {
-		this.children.forEach(function(item) {
+		var children = this.children;
+		for(var i = 0; i < children.length; i++) {
+			var item = children[i];
 			if(typeof item === "string")
 				hash.update(item);
 			else
 				item.updateHash(hash);
-		});
+		}
 	}
 }