[tfjs-core] backend for encodeBase64, decodeBase64

Author: vabarbosa

tfjs-core/src/backends/backend.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
@@ -17,7 +17,7 @@
 
 import {Conv2DInfo, Conv3DInfo} from '../ops/conv_util';
 import {FusedBatchMatMulConfig, FusedConv2DConfig} from '../ops/fused_util';
-import {Backend, DataId, Scalar, Tensor, Tensor1D, Tensor2D, Tensor3D, Tensor4D, Tensor5D} from '../tensor';
+import {Backend, DataId, Scalar, StringTensor, Tensor, Tensor1D, Tensor2D, Tensor3D, Tensor4D, Tensor5D} from '../tensor';
 import {BackendValues, DataType, PixelData, Rank, ShapeMap} from '../types';
 
 export const EPSILON_FLOAT32 = 1e-7;
@@ -650,4 +650,13 @@ export class KernelBackend implements TensorStorage, Backend, BackendTimer {
   dispose(): void {
     throw new Error('Not yet implemented');
   }
+
+  encodeBase64<T extends StringTensor>(str: StringTensor|Tensor, pad = false):
+      T {
+    throw new Error('Not yet implemented');
+  }
+
+  decodeBase64<T extends StringTensor>(str: StringTensor|Tensor): T {
+    throw new Error('Not yet implemented');
+  }
 }

tfjs-core/src/backends/cpu/backend_cpu.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
@@ -34,7 +34,7 @@ import {buffer, scalar, tensor, tensor3d, tensor4d} from '../../ops/ops';
 import * as scatter_nd_util from '../../ops/scatter_nd_util';
 import * as selu_util from '../../ops/selu_util';
 import {computeFlatOffset, computeOutShape, isSliceContinous} from '../../ops/slice_util';
-import {DataId, Scalar, Tensor, Tensor1D, Tensor2D, Tensor3D, Tensor4D, Tensor5D, TensorBuffer} from '../../tensor';
+import {DataId, Scalar, StringTensor, Tensor, Tensor1D, Tensor2D, Tensor3D, Tensor4D, Tensor5D, TensorBuffer} from '../../tensor';
 import {BackendValues, DataType, DataValues, NumericDataType, PixelData, Rank, ShapeMap, TypedArray, upcastType} from '../../types';
 import * as util from '../../util';
 import {getArrayFromDType, inferDtype, now, sizeFromShape} from '../../util';
@@ -43,6 +43,7 @@ import * as backend_util from '../backend_util';
 import * as complex_util from '../complex_util';
 import {nonMaxSuppressionImpl} from '../non_max_suppression_impl';
 import {split} from '../split_shared';
+import {decodeBase64Impl, encodeBase64Impl} from '../string_shared';
 import {tile} from '../tile_impl';
 import {topkImpl} from '../topk_impl';
 import {whereImpl} from '../where_impl';
@@ -3624,6 +3625,17 @@ export class MathBackendCPU implements KernelBackend {
 
   dispose() {}
 
+  encodeBase64<T extends StringTensor>(str: StringTensor|Tensor, pad = false):
+      T {
+    const sVals = this.readSync(str.dataId) as Uint8Array[];
+    return encodeBase64Impl(sVals, str.shape, pad);
+  }
+
+  decodeBase64<T extends StringTensor>(str: StringTensor|Tensor): T {
+    const sVals = this.readSync(str.dataId) as Uint8Array[];
+    return decodeBase64Impl(sVals, str.shape);
+  }
+
   floatPrecision(): 16|32 {
     return 32;
   }

tfjs-core/src/backends/string_shared.ts

@@ -0,0 +1,57 @@
+/**
+ * @license
+ * 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
+ *
+ * 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 {arrayBufferToBase64String, base64StringToArrayBuffer, urlSafeBase64, urlUnsafeBase64} from '../io/io_utils';
+import {StringTensor, Tensor} from '../tensor';
+import {decodeString} from '../util';
+
+/** Shared implementation of the encodeBase64 kernel across WebGL and CPU. */
+export function encodeBase64Impl<T extends StringTensor>(
+    values: Uint8Array[], shape: number[], pad = false): T {
+  const resultValues = new Array(values.length);
+
+  for (let i = 0; i < values.length; ++i) {
+    const bStr = arrayBufferToBase64String(values[i].buffer);
+    const bStrUrl = urlSafeBase64(bStr);
+
+    if (pad) {
+      resultValues[i] = bStrUrl;
+    } else {
+      // Remove padding
+      resultValues[i] = bStrUrl.replace(/=/g, '');
+    }
+  }
+
+  return Tensor.make(shape, {values: resultValues}, 'string');
+}
+
+/** Shared implementation of the decodeBase64 kernel across WebGL and CPU. */
+export function decodeBase64Impl<T extends StringTensor>(
+    values: Uint8Array[], shape: number[]): T {
+  const resultValues = new Array(values.length);
+
+  for (let i = 0; i < values.length; ++i) {
+    // Undo URL safe and decode from Base64 to ArrayBuffer
+    const bStrUrl = decodeString(values[i]);
+    const bStr = urlUnsafeBase64(bStrUrl);
+    const aBuff = base64StringToArrayBuffer(bStr);
+
+    resultValues[i] = decodeString(new Uint8Array(aBuff));
+  }
+
+  return Tensor.make(shape, {values: resultValues}, 'string');
+}

tfjs-core/src/backends/webgl/backend_webgl.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
@@ -37,7 +37,7 @@ import * as segment_util from '../../ops/segment_util';
 import * as slice_util from '../../ops/slice_util';
 import {softmax} from '../../ops/softmax';
 import {range, scalar, tensor} from '../../ops/tensor_ops';
-import {DataId, Scalar, Tensor, Tensor1D, Tensor2D, Tensor3D, Tensor4D, Tensor5D} from '../../tensor';
+import {DataId, Scalar, StringTensor, Tensor, Tensor1D, Tensor2D, Tensor3D, Tensor4D, Tensor5D} from '../../tensor';
 import {BackendValues, DataType, DataTypeMap, NumericDataType, PixelData, Rank, RecursiveArray, ShapeMap, sumOutType, TypedArray, upcastType} from '../../types';
 import * as util from '../../util';
 import {getArrayFromDType, getTypedArrayFromDType, inferDtype, sizeFromShape} from '../../util';
@@ -46,6 +46,7 @@ import * as backend_util from '../backend_util';
 import {mergeRealAndImagArrays} from '../complex_util';
 import {nonMaxSuppressionImpl} from '../non_max_suppression_impl';
 import {split} from '../split_shared';
+import {decodeBase64Impl, encodeBase64Impl} from '../string_shared';
 import {tile} from '../tile_impl';
 import {topkImpl} from '../topk_impl';
 import {whereImpl} from '../where_impl';
@@ -2412,6 +2413,17 @@ export class MathBackendWebGL implements KernelBackend {
     return split(x, sizeSplits, axis);
   }
 
+  encodeBase64<T extends StringTensor>(str: StringTensor|Tensor, pad = false):
+      T {
+    const sVals = this.readSync(str.dataId) as Uint8Array[];
+    return encodeBase64Impl(sVals, str.shape, pad);
+  }
+
+  decodeBase64<T extends StringTensor>(str: StringTensor|Tensor): T {
+    const sVals = this.readSync(str.dataId) as Uint8Array[];
+    return decodeBase64Impl(sVals, str.shape);
+  }
+
   scatterND<R extends Rank>(
       indices: Tensor, updates: Tensor, shape: ShapeMap[R]): Tensor<R> {
     const {sliceRank, numUpdates, sliceSize, strides, outputSize} =