[tfjs-core] encodeBase64, decodeBase64 ops

Author: vabarbosa

tfjs-core/src/ops/ops.ts

@@ -1,6 +1,6 @@
 /**
  * @license
- * Copyright 2018 Google Inc. All Rights Reserved.
+ * Copyright 2019 Google Inc. All Rights Reserved.
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
@@ -49,6 +49,7 @@ export * from './gather_nd';
 export * from './diag';
 export * from './dropout';
 export * from './signal_ops';
+export * from './string_ops';
 export * from './in_top_k';
 
 export {op} from './operation';

tfjs-core/src/ops/string_ops.ts

@@ -0,0 +1,78 @@
+/**
+ * @license
+ * Copyright 2019 Google LLC. All Rights Reserved.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * =============================================================================
+ */
+import {ENGINE} from '../engine';
+import {StringTensor, Tensor} from '../tensor';
+import {convertToTensor} from '../tensor_util_env';
+
+import {op} from './operation';
+
+/**
+ * Encodes the values of a `tf.Tensor` (of dtype `string`) to Base64.
+ *
+ * Given a String tensor, returns a new tensor with the values encoded into
+ * web-safe base64 format.
+ *
+ * Web-safe means that the encoder uses `-` and `_` instead of `+` and `/`:
+ *
+ * en.wikipedia.org/wiki/Base64
+ *
+ * ```js
+ * const x = tf.tensor1d(['Hello world!'], 'string');
+ *
+ * x.encodeBase64().print();
+ * ```
+ * @param str The input `tf.Tensor` of dtype `string` to encode.
+ * @param pad Whether to add padding (`=`) to the end of the encoded string.
+ */
+/** @doc {heading: 'Operations', subheading: 'String'} */
+function encodeBase64_<T extends StringTensor>(
+    str: StringTensor|Tensor, pad = false): T {
+  const $str = convertToTensor(str, 'str', 'encodeBase64', 'string');
+
+  const backwardsFunc = (dy: T) => ({$str: () => decodeBase64(dy)});
+
+  return ENGINE.runKernel(
+      backend => backend.encodeBase64($str, pad), {$str}, backwardsFunc);
+}
+
+/**
+ * Decodes the values of a `tf.Tensor` (of dtype `string`) from Base64.
+ *
+ * Given a String tensor of Base64 encoded values, returns a new tensor with the
+ * decoded values.
+ *
+ * en.wikipedia.org/wiki/Base64
+ *
+ * ```js
+ * const y = tf.scalar('SGVsbG8gd29ybGQh', 'string');
+ *
+ * y.decodeBase64().print();
+ * ```
+ * @param str The input `tf.Tensor` of dtype `string` to decode.
+ */
+/** @doc {heading: 'Operations', subheading: 'String'} */
+function decodeBase64_<T extends StringTensor>(str: StringTensor|Tensor): T {
+  const $str = convertToTensor(str, 'str', 'decodeBase64', 'string');
+
+  const backwardsFunc = (dy: T) => ({$str: () => encodeBase64(dy)});
+
+  return ENGINE.runKernel(
+      backend => backend.decodeBase64($str), {$str}, backwardsFunc);
+}
+
+export const encodeBase64 = op({encodeBase64_});
+export const decodeBase64 = op({decodeBase64_});

tfjs-core/src/tensor.ts

@@ -1,6 +1,6 @@
 /**
  * @license
- * Copyright 2017 Google Inc. All Rights Reserved.
+ * Copyright 2019 Google Inc. All Rights Reserved.
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
@@ -367,6 +367,8 @@ export interface OpHandler {
     fft(x: Tensor): Tensor; ifft(x: Tensor): Tensor; rfft(x: Tensor): Tensor;
     irfft(x: Tensor): Tensor
   };
+  encodeBase64<T extends StringTensor>(x: T, pad: boolean): T;
+  decodeBase64<T extends StringTensor>(x: T): T;
 }
 
 // For tracking tensor creation and disposal.
@@ -1426,6 +1428,16 @@ export class Tensor<R extends Rank = Rank> {
     this.throwIfDisposed();
     return opHandler.spectral.irfft(this);
   }
+
+  encodeBase64<T extends StringTensor>(this: T, pad = false): T {
+    this.throwIfDisposed();
+    return opHandler.encodeBase64(this, pad);
+  }
+
+  decodeBase64<T extends StringTensor>(this: T): T {
+    this.throwIfDisposed();
+    return opHandler.decodeBase64(this);
+  }
 }
 Object.defineProperty(Tensor, Symbol.hasInstance, {
   value: (instance: Tensor) => {