turned resolvePath into generic utility function

there's really no need for this to be an instance method

while technically, this constitutes a breaking change (due to
`lib/util/resolve.js`), we're pretty sure nobody else was using
`resolveModulePath`.

Author: FND

lib/index.js

@@ -1,6 +1,7 @@
 "use strict";
 
 let AssetManager = require("./manager");
+let resolvePath = require("./util/resolve");
 let { abort, repr } = require("./util");
 let browserslist = require("browserslist");
 let SerializedRunner = require("./util/runner");
@@ -61,7 +62,7 @@ module.exports = (referenceDir, config, { watch, fingerprint, sourcemaps, compac
 	runner.run();
 
 	if(watch) {
-		makeWatcher(config.watchDirs, referenceDir, assetManager.resolvePath).
+		makeWatcher(config.watchDirs, referenceDir).
 			on("edit", filepaths => {
 				runner.rerun(filepaths);
 			});
@@ -73,11 +74,12 @@ function buildStep(plugins) {
 		then(() => files);
 }
 
-function makeWatcher(watchDirs, referenceDir, resolvePath) {
+function makeWatcher(watchDirs, referenceDir) {
 	let niteOwl = require("nite-owl");
 
 	if(watchDirs) {
-		watchDirs = watchDirs.map(dir => resolvePath(dir, { enforceRelative: true }));
+		watchDirs = watchDirs.map(dir => resolvePath(dir, referenceDir,
+				{ enforceRelative: true }));
 	} else {
 		watchDirs = [referenceDir];
 		console.error(`you might consider setting ${repr("watchDirs", false)} ` +

lib/manager.js

@@ -1,9 +1,9 @@
 "use strict";
 
 let Manifest = require("./manifest");
-let resolveModulePath = require("./util/resolve");
 let createFile = require("./util/files");
-let { abort, generateFingerprint, repr } = require("./util");
+let resolvePath = require("./util/resolve");
+let { abort, generateFingerprint } = require("./util");
 let path = require("path");
 
 module.exports = class AssetManager {
@@ -12,11 +12,10 @@ module.exports = class AssetManager {
 		this.fingerprint = fingerprint;
 		this.exitOnError = exitOnError;
 
-		// bind methods for convenience
-		this.writeFile = this.writeFile.bind(this);
-		this.resolvePath = this.resolvePath.bind(this);
+		this.writeFile = this.writeFile.bind(this); // for convenience
+		this.resolvePath = filepath => resolvePath(filepath, referenceDir);
 
-		this.manifest = new Manifest(manifestConfig || {}, this.resolvePath);
+		this.manifest = new Manifest(referenceDir, manifestConfig || {});
 	}
 
 	// NB: `fingerprint` option takes precedence over corresponding instance property
@@ -44,20 +43,6 @@ module.exports = class AssetManager {
 			});
 	}
 
-	resolvePath(filepath, { enforceRelative } = {}) {
-		if(filepath.substr(0, 2) === "./") {
-			return path.resolve(this.referenceDir, filepath);
-		} else if(enforceRelative) {
-			abort(`ERROR: path must be relative: ${repr(filepath)}`);
-		} else { // attempt via Node resolution algorithm
-			try {
-				return resolveModulePath(filepath, this.referenceDir);
-			} catch(err) {
-				abort(`ERROR: could not resolve ${repr(filepath)}`);
-			}
-		}
-	}
-
 	get packagesDir() {
 		let memo = this._packagesDir;
 		if(!memo) {

lib/manifest.js

@@ -1,13 +1,14 @@
 "use strict";
 
-let path = require("path");
 let createFile = require("./util/files");
+let resolvePath = require("./util/resolve");
 let { abort } = require("./util");
+let path = require("path");
 
 module.exports = class Manifest {
-	constructor({ target, key, value, baseURI, webRoot }, resolvePath) {
+	constructor(referenceDir, { target, key, value, baseURI, webRoot }) {
 		if(target) {
-			this.filepath = resolvePath(target, {
+			this.filepath = resolvePath(target, referenceDir, {
 				enforceRelative: true
 			});
 		}
@@ -26,7 +27,8 @@ module.exports = class Manifest {
 			this.valueTransform = value;
 		} else {
 			baseURI = baseURI || "/";
-			webRoot = resolvePath(webRoot || "./", { enforceRelative: true });
+			webRoot = resolvePath(webRoot || "./", referenceDir,
+					{ enforceRelative: true });
 			this.valueTransform = filepath => baseURI + path.relative(webRoot, filepath);
 		}
 	}

lib/util/resolve.js

@@ -1,5 +1,8 @@
 "use strict";
 
+let { abort, repr } = require("./");
+let path = require("path");
+
 // older versions of Node do not support `require.resolve`'s `paths` option
 let legacy = !require.resolve.paths;
 if(!legacy) { // account for bug in Node v8.9.4 and below
@@ -10,7 +13,21 @@ if(!legacy) { // account for bug in Node v8.9.4 and below
 	}
 }
 
-module.exports = function resolveModulePath(filepath, rootDir) {
+module.exports = function resolvePath(filepath, referenceDir, { enforceRelative } = {}) {
+	if(filepath.substr(0, 2) === "./") {
+		return path.resolve(referenceDir, filepath);
+	} else if(enforceRelative) {
+		abort(`ERROR: path must be relative: ${repr(filepath)}`);
+	} else { // attempt via Node resolution algorithm
+		try {
+			return resolveModulePath(filepath, referenceDir);
+		} catch(err) {
+			abort(`ERROR: could not resolve ${repr(filepath)}`);
+		}
+	}
+};
+
+function resolveModulePath(filepath, rootDir) {
 	if(legacy) {
 		legacy = process.env.NODE_PATH; // cache previous value
 		rootDir = rootDir.replace(/\/{1,}$/, ""); // strip trailing slashes, to be safe
@@ -26,4 +43,4 @@ module.exports = function resolveModulePath(filepath, rootDir) {
 	}
 
 	return res;
-};
+}