Use node url api (#114)

* check if url is supported before using

* let instead of var

* use npm Url

* switch back to private member

* update unit tests

* test for relative path

package.json

@@ -58,6 +58,7 @@
   },
   "dependencies": {
     "@types/long": "~3.0.32",
-    "protobufjs": "~6.8.0"
+    "protobufjs": "~6.8.0",
+    "url": "^0.11.0"
   }
 }

src/executor/frozen_model.ts

@@ -21,6 +21,7 @@ import {NamedTensorMap, NamedTensorsMap, tensorflow} from '../data/index';
 import {OperationMapper} from '../operations/index';
 
 import {GraphExecutor} from './graph_executor';
+import * as Url from 'url';
 
 export class FrozenModel {
   private executor: GraphExecutor;
@@ -42,22 +43,18 @@ export class FrozenModel {
   constructor(
       private modelUrl: string, private weightManifestUrl: string,
       private requestOption?: RequestInit) {
-    this.getPathPrefix();
+    this.pathPrefix = this.getPathPrefix();
   }
 
-  private getPathPrefix() {
-    const isAbsolute = /^[a-z][a-z0-9+.-]*:/.test(this.weightManifestUrl);
-    if (isAbsolute) {
-      const url = new URL(this.weightManifestUrl);
-      const segments = url.pathname.split('/');
-      segments.splice(-1);
-      url.pathname = segments.join('/');
-      this.pathPrefix = url.toString();
-    } else {
-      const segments = this.weightManifestUrl.split('/');
-      segments.splice(-1);
-      this.pathPrefix = segments.join('/');
-    }
+  /**
+   * Returns the path prefix for this.weightManifestUrl.
+   */
+  getPathPrefix() {
+    const url = Url.parse(this.weightManifestUrl);
+    const segments = url.pathname.split('/');
+    segments.splice(-1);
+    url.pathname = segments.join('/');
+    return Url.format(url) + '/';
   }
 
   /**

src/executor/frozen_model_test.ts

@@ -81,6 +81,18 @@ describe('Model', () => {
     expect(loaded).toBe(true);
   });
 
+  describe('getPathPrefix', () => {
+    it('should set pathPrefix (absolute path)', async () => {
+      model = new FrozenModel(MODEL_URL, WEIGHT_MANIFEST_URL);
+      expect(model.getPathPrefix()).toEqual("http://example.org/");
+    });
+
+    it('should set pathPrefix (relative path)', async () => {
+      model = new FrozenModel(RELATIVE_MODEL_URL, RELATIVE_WEIGHT_MANIFEST_URL);
+      expect(model.getPathPrefix()).toEqual("/path/");
+    });
+  });
+
   describe('eval', () => {
     it('should generate the output', async () => {
       await model.load();