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Introduce utility class and refactor
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,156 @@ | ||
| /* | ||
| * Copyright (c) Facebook, Inc. and its affiliates. | ||
| * | ||
| * 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. | ||
| */ | ||
| #pragma once | ||
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| #include <string> | ||
| #include "velox/common/base/Status.h" | ||
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| namespace facebook::velox::encoding { | ||
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| /// Padding character used in encoding. | ||
| const static char kPadding = '='; | ||
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| // Checks if the input Base64 string is padded. | ||
| static inline bool isPadded(std::string_view input) { | ||
| size_t inputSize{input.size()}; | ||
| return (inputSize > 0 && input[inputSize - 1] == kPadding); | ||
| } | ||
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| // Counts the number of padding characters in encoded input. | ||
| static inline size_t numPadding(std::string_view input) { | ||
| size_t numPadding{0}; | ||
| size_t inputSize{input.size()}; | ||
| while (inputSize > 0 && input[inputSize - 1] == kPadding) { | ||
| numPadding++; | ||
| inputSize--; | ||
| } | ||
| return numPadding; | ||
| } | ||
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| // Validate the character in charset with ReverseIndex table | ||
| template <typename Charset, typename ReverseIndex> | ||
| constexpr bool checkForwardIndex( | ||
| uint8_t index, | ||
| const Charset& charset, | ||
| const ReverseIndex& reverseIndex) { | ||
| return (reverseIndex[static_cast<uint8_t>(charset[index])] == index) && | ||
| (index > 0 ? checkForwardIndex(index - 1, charset, reverseIndex) : true); | ||
| } | ||
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| // Searches for a character within a charset up to a certain index. | ||
| template <typename Charset> | ||
| constexpr bool findCharacterInCharset( | ||
| const Charset& charset, | ||
| uint8_t index, | ||
| const char targetChar) { | ||
| return index < charset.size() && | ||
| ((charset[index] == targetChar) || | ||
| findCharacterInCharset(charset, index + 1, targetChar)); | ||
| } | ||
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| // Checks the consistency of a reverse index mapping for a given character set. | ||
| template <typename Charset, typename ReverseIndex> | ||
| constexpr bool checkReverseIndex( | ||
| uint8_t index, | ||
| const Charset& charset, | ||
| const ReverseIndex& reverseIndex) { | ||
| return (reverseIndex[index] == 255 | ||
| ? !findCharacterInCharset(charset, 0, static_cast<char>(index)) | ||
| : (charset[reverseIndex[index]] == index)) && | ||
| (index > 0 ? checkReverseIndex(index - 1, charset, reverseIndex) : true); | ||
| } | ||
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| template <typename ReverseIndexType> | ||
| uint8_t reverseLookup( | ||
| char encodedChar, | ||
| const ReverseIndexType& reverseIndex, | ||
| Status& status, | ||
| uint8_t kBase) { | ||
| auto curr = reverseIndex[static_cast<uint8_t>(encodedChar)]; | ||
| if (curr >= kBase) { | ||
| status = | ||
| Status::UserError("invalid input string: contains invalid characters."); | ||
| return 0; // Return 0 or any other error code indicating failure | ||
| } | ||
| return curr; | ||
| } | ||
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| // Returns the actual size of the decoded data. Will also remove the padding | ||
| // length from the 'inputSize'. | ||
| static Status calculateDecodedSize( | ||
| std::string_view input, | ||
| size_t& inputSize, | ||
| size_t& decodedSize, | ||
| const int binaryBlockByteSize, | ||
| const int encodedBlockByteSize) { | ||
| if (inputSize == 0) { | ||
| decodedSize = 0; | ||
| return Status::OK(); | ||
| } | ||
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| // Check if the input string is padded | ||
| if (isPadded(input)) { | ||
| // If padded, ensure that the string length is a multiple of the encoded | ||
| // block size | ||
| if (inputSize % encodedBlockByteSize != 0) { | ||
| return Status::UserError( | ||
| "decode() - invalid input string: " | ||
| "string length is not a multiple of the encoded block size."); | ||
| } | ||
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| decodedSize = (inputSize * binaryBlockByteSize) / encodedBlockByteSize; | ||
| auto paddingCount = numPadding(input); | ||
| inputSize -= paddingCount; | ||
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| // Adjust the needed size by deducting the bytes corresponding to the | ||
| // padding from the calculated size. | ||
| decodedSize -= | ||
| ((paddingCount * binaryBlockByteSize) + (encodedBlockByteSize - 1)) / | ||
| encodedBlockByteSize; | ||
| } else { | ||
| decodedSize = (inputSize * binaryBlockByteSize) / encodedBlockByteSize; | ||
| } | ||
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| return Status::OK(); | ||
| } | ||
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| // Calculates the encoded size based on input size. | ||
| static size_t calculateEncodedSize( | ||
| size_t inputSize, | ||
| bool includePadding, | ||
| const int binaryBlockByteSize, | ||
| const int encodedBlockByteSize) { | ||
| if (inputSize == 0) { | ||
| return 0; | ||
| } | ||
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| // Calculate the output size assuming that we are including padding. | ||
| size_t encodedSize = | ||
| ((inputSize + binaryBlockByteSize - 1) / binaryBlockByteSize) * | ||
| encodedBlockByteSize; | ||
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| if (!includePadding) { | ||
| // If the padding was not requested, subtract the padding bytes. | ||
| size_t remainder = inputSize % binaryBlockByteSize; | ||
| if (remainder != 0) { | ||
| encodedSize -= (binaryBlockByteSize - remainder); | ||
| } | ||
| } | ||
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| return encodedSize; | ||
| } | ||
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| } // namespace facebook::velox::encoding |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,35 @@ | ||
| /* | ||
| * Copyright (c) Facebook, Inc. and its affiliates. | ||
| * | ||
| * 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. | ||
| */ | ||
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| #include <gtest/gtest.h> | ||
| #include "velox/common/base/tests/GTestUtils.h" | ||
| #include "velox/common/encode/EncoderUtils.h" | ||
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| namespace facebook::velox::encoding { | ||
| class EncoderUtilsTest : public ::testing::Test {}; | ||
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| TEST_F(EncoderUtilsTest, isPadded) { | ||
| EXPECT_TRUE(isPadded("ABC=")); | ||
| EXPECT_FALSE(isPadded("ABC")); | ||
| } | ||
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| TEST_F(EncoderUtilsTest, numPadding) { | ||
| EXPECT_EQ(0, numPadding("ABC")); | ||
| EXPECT_EQ(1, numPadding("ABC=")); | ||
| EXPECT_EQ(2, numPadding("AB==")); | ||
| } | ||
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| } // namespace facebook::velox::encoding |