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82 строки
2.2 KiB
82 строки
2.2 KiB
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file. See the AUTHORS file for names of contributors.
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#include "util/logging.h"
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#include <cstdarg>
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#include <cstdio>
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#include <cstdlib>
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#include <limits>
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#include "leveldb/env.h"
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#include "leveldb/slice.h"
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namespace leveldb {
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void AppendNumberTo(std::string* str, uint64_t num) {
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char buf[30];
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std::snprintf(buf, sizeof(buf), "%llu", static_cast<unsigned long long>(num));
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str->append(buf);
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}
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void AppendEscapedStringTo(std::string* str, const Slice& value) {
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for (size_t i = 0; i < value.size(); i++) {
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char c = value[i];
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if (c >= ' ' && c <= '~') {
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str->push_back(c);
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} else {
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char buf[10];
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std::snprintf(buf, sizeof(buf), "\\x%02x",
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static_cast<unsigned int>(c) & 0xff);
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str->append(buf);
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}
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}
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}
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std::string NumberToString(uint64_t num) {
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std::string r;
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AppendNumberTo(&r, num);
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return r;
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}
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std::string EscapeString(const Slice& value) {
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std::string r;
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AppendEscapedStringTo(&r, value);
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return r;
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}
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bool ConsumeDecimalNumber(Slice* in, uint64_t* val) {
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// Constants that will be optimized away.
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constexpr const uint64_t kMaxUint64 = std::numeric_limits<uint64_t>::max();
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constexpr const char kLastDigitOfMaxUint64 =
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'0' + static_cast<char>(kMaxUint64 % 10);
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uint64_t value = 0;
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// reinterpret_cast-ing from char* to uint8_t* to avoid signedness.
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const uint8_t* start = reinterpret_cast<const uint8_t*>(in->data());
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const uint8_t* end = start + in->size();
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const uint8_t* current = start;
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for (; current != end; ++current) {
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const uint8_t ch = *current;
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if (ch < '0' || ch > '9') break;
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// Overflow check.
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// kMaxUint64 / 10 is also constant and will be optimized away.
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if (value > kMaxUint64 / 10 ||
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(value == kMaxUint64 / 10 && ch > kLastDigitOfMaxUint64)) {
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return false;
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}
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value = (value * 10) + (ch - '0');
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}
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*val = value;
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const size_t digits_consumed = current - start;
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in->remove_prefix(digits_consumed);
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return digits_consumed != 0;
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}
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} // namespace leveldb
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