refactor storage of replacements for readability and performance

lib/ReplaceSource.js

@@ -10,24 +10,35 @@ var SourceListMap = require("source-list-map").SourceListMap;
 var fromStringWithSourceMap = require("source-list-map").fromStringWithSourceMap;
 var SourceMapConsumer = require("source-map").SourceMapConsumer;
 
+class Replacement {
+	constructor(start, end, content, insertIndex, name) {
+		this.start = start;
+		this.end = end;
+		this.content = content;
+		this.insertIndex = insertIndex;
+		this.name = name;
+	}
+}
+
 class ReplaceSource extends Source {
 	constructor(source, name) {
 		super();
 		this._source = source;
 		this._name = name;
+		/** @type {Replacement[]} */
 		this.replacements = [];
 	}
 
 	replace(start, end, newValue, name) {
 		if(typeof newValue !== "string")
 			throw new Error("insertion must be a string, but is a " + typeof newValue);
-		this.replacements.push([start, end, newValue, this.replacements.length, name]);
+		this.replacements.push(new Replacement(start, end, newValue, this.replacements.length, name));
 	}
 
 	insert(pos, newValue, name) {
 		if(typeof newValue !== "string")
 			throw new Error("insertion must be a string, but is a " + typeof newValue + ": " + newValue);
-		this.replacements.push([pos, pos - 1, newValue, this.replacements.length, name]);
+		this.replacements.push(new Replacement(pos, pos - 1, newValue, this.replacements.length, name));
 	}
 
 	source(options) {
@@ -40,13 +51,13 @@ class ReplaceSource extends Source {
 
 	_sortReplacements() {
 		this.replacements.sort(function(a, b) {
-			var diff = b[1] - a[1];
+			var diff = b.end - a.end;
 			if(diff !== 0)
 				return diff;
-			diff = b[0] - a[0];
+			diff = b.start - a.start;
 			if(diff !== 0)
 				return diff;
-			return b[3] - a[3];
+			return b.insertIndex - a.insertIndex;
 		});
 	}
 
@@ -57,9 +68,9 @@ class ReplaceSource extends Source {
 		var result = [str];
 		this.replacements.forEach(function(repl) {
 			var remSource = result.pop();
-			var splitted1 = this._splitString(remSource, Math.floor(repl[1] + 1));
-			var splitted2 = this._splitString(splitted1[0], Math.floor(repl[0]));
-			result.push(splitted1[1], repl[2], splitted2[0]);
+			var splitted1 = this._splitString(remSource, Math.floor(repl.end + 1));
+			var splitted2 = this._splitString(splitted1[0], Math.floor(repl.start));
+			result.push(splitted1[1], repl.content, splitted2[0]);
 		}, this);
 
 		// write out result array in reverse order
@@ -146,18 +157,18 @@ class ReplaceSource extends Source {
 					removeChars = 0;
 				}
 				var finalStr = "";
-				while(idxReplacement >= 0 && replacements[idxReplacement][0] < newCurrentIndex) {
+				while(idxReplacement >= 0 && replacements[idxReplacement].start < newCurrentIndex) {
 					var repl = replacements[idxReplacement];
-					var start = Math.floor(repl[0]);
-					var end = Math.floor(repl[1] + 1);
+					var start = Math.floor(repl.start);
+					var end = Math.floor(repl.end + 1);
 					var before = str.substr(0, Math.max(0, start - currentIndex));
 					if(end <= newCurrentIndex) {
 						var after = str.substr(Math.max(0, end - currentIndex));
-						finalStr += before + repl[2];
+						finalStr += before + repl.content;
 						str = after;
 						currentIndex = Math.max(currentIndex, end);
 					} else {
-						finalStr += before + repl[2];
+						finalStr += before + repl.content;
 						str = "";
 						removeChars = end - newCurrentIndex;
 					}
@@ -170,7 +181,7 @@ class ReplaceSource extends Source {
 		});
 		var extraCode = "";
 		while(idxReplacement >= 0) {
-			extraCode += replacements[idxReplacement][2];
+			extraCode += replacements[idxReplacement].content;
 			idxReplacement--;
 		}
 		if(extraCode) {
@@ -260,16 +271,19 @@ class ReplaceSource extends Source {
 }
 
 function sortReplacementsAscending(a, b) {
-	var diff = a[1] - b[1]; // end
+	var diff = a.end - b.end;
 	if(diff !== 0)
 		return diff;
-	diff = a[0] - b[0]; // start
+	diff = a.start - b.start;
 	if(diff !== 0)
 		return diff;
-	return a[3] - b[3]; // insert order
+	return a.insertIndex - b.insertIndex;
 }
 
 class ReplacementEnumerator {
+	/**
+	 * @param {Replacement[]} replacements list of replacements
+	 */
 	constructor(replacements) {
 		this.emit = true;
 		this.done = !replacements || replacements.length === 0;
@@ -278,7 +292,7 @@ class ReplacementEnumerator {
 		if(!this.done) {
 			// Set initial start position in case .header is not called
 			var repl = replacements[0];
-			this.position = Math.floor(repl[0]);
+			this.position = Math.floor(repl.start);
 			if(this.position < 0)
 				this.position = 0;
 		}
@@ -290,18 +304,18 @@ class ReplacementEnumerator {
 		if(this.emit) {
 			// Start point found. stop emitting. set position to find end
 			var repl = this.replacements[this.index];
-			var end = Math.floor(repl[1] + 1);
+			var end = Math.floor(repl.end + 1);
 			this.position = end;
-			this.value = repl[2];
-			this.name = repl[4];
+			this.value = repl.content;
+			this.name = repl.name;
 		} else {
 			// End point found. start emitting. set position to find next start
 			this.index++;
 			if(this.index >= this.replacements.length) {
 				this.done = true;
 			} else {
 				var nextRepl = this.replacements[this.index];
-				var start = Math.floor(nextRepl[0]);
+				var start = Math.floor(nextRepl.start);
 				this.position = start;
 			}
 		}
@@ -315,7 +329,9 @@ class ReplacementEnumerator {
 		if(!this.done && !this.emit)
 			this.next(); // If we finished _replaceInNode mid emit we advance to next entry
 		return this.done ? [] : this.replacements.slice(this.index).map(function(repl) {
-			return repl[2];
+			// this doesn't need to handle repl.name, because in SourceMaps generated code
+			// without pointer to original source can't have a name
+			return repl.content;
 		}).join("");
 	}
 }