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/* Copyright 2012 10gen Inc.
*
* 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.
*/
#include "mongo/base/parse_number.h"
#include <limits>
#include "mongo/platform/cstdint.h"
namespace mongo {
/**
* Returns the value of the digit "c", with the same conversion behavior as strtol.
*
* Assumes "c" is an ASCII character or UTF-8 octet.
*/
static uint8_t _digitValue(char c) {
if (c >= '0' && c <= '9')
return uint8_t(c - '0');
if (c >= 'a' && c <= 'z')
return uint8_t(c - 'a' + 10);
if (c >= 'A' && c <= 'Z')
return uint8_t(c - 'A' + 10);
return 36; // Illegal digit value for all supported bases.
}
/**
* Assuming "stringValue" represents a parseable number, extracts the sign and returns a
* substring with any sign characters stripped away. "*isNegative" is set to true if the
* number is negative, and false otherwise.
*/
static inline StringData _extractSign(const StringData& stringValue, bool* isNegative) {
if (stringValue.empty()) {
*isNegative = false;
return stringValue;
}
bool foundSignMarker;
switch (stringValue[0]) {
case '-':
foundSignMarker = true;
*isNegative = true;
break;
case '+':
foundSignMarker = true;
*isNegative = false;
break;
default:
foundSignMarker = false;
*isNegative = false;
break;
}
if (foundSignMarker)
return stringValue.substr(1);
return stringValue;
}
/**
* Assuming "stringValue" represents a parseable number, determines what base to use given
* "inputBase". Stores the correct base into "*outputBase". Follows strtol rules. If
* "inputBase" is not 0, *outputBase is set to "inputBase". Otherwise, if "stringValue" starts
* with "0x" or "0X", sets outputBase to 16, or if it starts with 0, sets outputBase to 8.
*
* Returns the substring of "stringValue" with the base-indicating prefix stripped off.
*/
static inline StringData _extractBase(
const StringData& stringValue, int inputBase, int* outputBase) {
if (inputBase == 0) {
if (stringValue.size() == 0) {
*outputBase = inputBase;
return stringValue;
}
if (stringValue[0] == '0') {
if (stringValue.size() > 1 && (stringValue[1] == 'x' || stringValue[1] == 'X')) {
*outputBase = 16;
return stringValue.substr(2);
}
*outputBase = 8;
return stringValue.substr(1);
}
*outputBase = 10;
return stringValue;
}
else {
*outputBase = inputBase;
if (inputBase == 16) {
StringData prefix = stringValue.substr(0, 2);
if (prefix == "0x" || prefix == "0X")
return stringValue.substr(2);
}
return stringValue;
}
}
template <typename NumberType>
Status parseNumberFromStringWithBase(
const StringData& stringValue, int base, NumberType* result) {
typedef ::std::numeric_limits<NumberType> limits;
if (base == 1 || base < 0 || base > 36)
return Status(ErrorCodes::BadValue, "Invalid base", 0);
if (stringValue.size() == 0)
return Status(ErrorCodes::FailedToParse, "Empty string");
bool isNegative = false;
StringData str = _extractBase(_extractSign(stringValue, &isNegative), base, &base);
NumberType n(0);
if (isNegative) {
if (limits::is_signed) {
for (size_t i = 0; i < str.size(); ++i) {
NumberType digitValue = NumberType(_digitValue(str[i]));
if (int(digitValue) >= base)
return Status(ErrorCodes::FailedToParse, "Bad digit");
if ((NumberType(limits::min() / base) > n) ||
((limits::min() - NumberType(n * base)) > -digitValue)) {
return Status(ErrorCodes::FailedToParse, "Underflow");
}
n *= NumberType(base);
n -= NumberType(digitValue);
}
}
else {
return Status(ErrorCodes::FailedToParse, "Negative value");
}
}
else {
for (size_t i = 0; i < str.size(); ++i) {
NumberType digitValue = NumberType(_digitValue(str[i]));
if (int(digitValue) >= base)
return Status(ErrorCodes::FailedToParse, "Bad digit");
if ((NumberType(limits::max() / base) < n) ||
(NumberType(limits::max() - n * base) < digitValue)) {
return Status(ErrorCodes::FailedToParse, "Overflow");
}
n *= NumberType(base);
n += NumberType(digitValue);
}
}
*result = n;
return Status::OK();
}
// Definition of the various supported implementations of parseNumberFromStringWithBase.
#define DEFINE_PARSE_NUMBER_FROM_STRING_WITH_BASE(NUMBER_TYPE) \
template Status parseNumberFromStringWithBase<NUMBER_TYPE>(const StringData&, int, NUMBER_TYPE*);
DEFINE_PARSE_NUMBER_FROM_STRING_WITH_BASE(long)
DEFINE_PARSE_NUMBER_FROM_STRING_WITH_BASE(long long)
DEFINE_PARSE_NUMBER_FROM_STRING_WITH_BASE(unsigned long)
DEFINE_PARSE_NUMBER_FROM_STRING_WITH_BASE(unsigned long long)
DEFINE_PARSE_NUMBER_FROM_STRING_WITH_BASE(short)
DEFINE_PARSE_NUMBER_FROM_STRING_WITH_BASE(unsigned short)
DEFINE_PARSE_NUMBER_FROM_STRING_WITH_BASE(int)
DEFINE_PARSE_NUMBER_FROM_STRING_WITH_BASE(unsigned int)
DEFINE_PARSE_NUMBER_FROM_STRING_WITH_BASE(int8_t);
DEFINE_PARSE_NUMBER_FROM_STRING_WITH_BASE(uint8_t);
} // namespace mongo
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