blob: 18afd5e07d99d4b1c81e541398beb3869f78faf7 [file] [log] [blame]
// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/string_number_conversions.h"
#include <ctype.h>
#include <errno.h>
#include <stdlib.h>
#include <wctype.h>
#include <limits>
#include "base/compiler_specific.h"
#include "base/logging.h"
#include "base/third_party/dmg_fp/dmg_fp.h"
#include "base/utf_string_conversions.h"
namespace base {
namespace {
// The following template is used to convert a size in bytes value into an
// unsigned integral type. For example, if we want to use the unsigned type
// corresponding to int, we can use type MakeUnsigned<sizeof(int)>::Unsigned.
template <size_t size_in_bytes>
struct MakeUnsigned {};
template <>
struct MakeUnsigned<1> {
typedef uint8 Unsigned;
};
template <>
struct MakeUnsigned<2> {
typedef uint16 Unsigned;
};
template <>
struct MakeUnsigned<4> {
typedef uint32 Unsigned;
};
template <>
struct MakeUnsigned<8> {
typedef uint64 Unsigned;
};
template <typename STR, typename INT>
struct IntToStringT {
static STR IntToString(INT value) {
// log10(2) ~= 0.3 bytes needed per bit or per byte log10(2**8) ~= 2.4.
// So round up to allocate 3 output characters per byte, plus 1 for '-'.
const int kOutputBufSize = 3 * sizeof(INT) + 1;
// Allocate the whole string right away, we will right back to front, and
// then return the substr of what we ended up using.
STR outbuf(kOutputBufSize, 0);
// We cannot directly use 'value < 0' as it will generate a warning on
// unsigned types in certain compilers because such check is meaningless.
bool is_neg = value < 1 && value != 0;
// We cannot simply use '-value' as it will generate a warning on unsigned
// types in certain compilers which treats such operation as invalid.
typename MakeUnsigned<sizeof(value)>::Unsigned res =
is_neg ? 0 - value : value;
for (typename STR::iterator it = outbuf.end();;) {
DCHECK(it != outbuf.begin());
--it;
*it = static_cast<typename STR::value_type>((res % 10) + '0');
res /= 10;
// We're done..
if (res == 0) {
if (is_neg) {
DCHECK(it != outbuf.begin());
--it;
*it = static_cast<typename STR::value_type>('-');
}
return STR(it, outbuf.end());
}
}
NOTREACHED();
return STR();
}
};
// Utility to convert a character to a digit in a given base
template<typename CHAR, int BASE, bool BASE_LTE_10> class BaseCharToDigit {
};
// Faster specialization for bases <= 10
template<typename CHAR, int BASE> class BaseCharToDigit<CHAR, BASE, true> {
public:
static bool Convert(CHAR c, uint8* digit) {
if (c >= '0' && c < '0' + BASE) {
*digit = c - '0';
return true;
}
return false;
}
};
// Specialization for bases where 10 < base <= 36
template<typename CHAR, int BASE> class BaseCharToDigit<CHAR, BASE, false> {
public:
static bool Convert(CHAR c, uint8* digit) {
if (c >= '0' && c <= '9') {
*digit = c - '0';
} else if (c >= 'a' && c < 'a' + BASE - 10) {
*digit = c - 'a' + 10;
} else if (c >= 'A' && c < 'A' + BASE - 10) {
*digit = c - 'A' + 10;
} else {
return false;
}
return true;
}
};
template<int BASE, typename CHAR> bool CharToDigit(CHAR c, uint8* digit) {
return BaseCharToDigit<CHAR, BASE, BASE <= 10>::Convert(c, digit);
}
// There is an IsWhitespace for wchars defined in string_util.h, but it is
// locale independent, whereas the functions we are replacing were
// locale-dependent. TBD what is desired, but for the moment let's not introduce
// a change in behaviour.
template<typename CHAR> class WhitespaceHelper {
};
template<> class WhitespaceHelper<char> {
public:
static bool Invoke(char c) {
return 0 != isspace(static_cast<unsigned char>(c));
}
};
template<> class WhitespaceHelper<char16> {
public:
static bool Invoke(char16 c) {
return 0 != iswspace(c);
}
};
template<typename CHAR> bool LocalIsWhitespace(CHAR c) {
return WhitespaceHelper<CHAR>::Invoke(c);
}
// IteratorRangeToNumberTraits should provide:
// - a typedef for iterator_type, the iterator type used as input.
// - a typedef for value_type, the target numeric type.
// - static functions min, max (returning the minimum and maximum permitted
// values)
// - constant kBase, the base in which to interpret the input
template<typename IteratorRangeToNumberTraits>
class IteratorRangeToNumber {
public:
typedef IteratorRangeToNumberTraits traits;
typedef typename traits::iterator_type const_iterator;
typedef typename traits::value_type value_type;
// Generalized iterator-range-to-number conversion.
//
static bool Invoke(const_iterator begin,
const_iterator end,
value_type* output) {
bool valid = true;
while (begin != end && LocalIsWhitespace(*begin)) {
valid = false;
++begin;
}
if (begin != end && *begin == '-') {
if (!Negative::Invoke(begin + 1, end, output)) {
valid = false;
}
// For unsigned types, any negative value is invalid and will be set to 0.
if (traits::min() == 0) {
if (*output != 0) {
valid = false;
}
*output = 0;
}
} else {
if (begin != end && *begin == '+') {
++begin;
}
if (!Positive::Invoke(begin, end, output)) {
valid = false;
}
}
return valid;
}
private:
// Sign provides:
// - a static function, CheckBounds, that determines whether the next digit
// causes an overflow/underflow
// - a static function, Increment, that appends the next digit appropriately
// according to the sign of the number being parsed.
template<typename Sign>
class Base {
public:
static bool Invoke(const_iterator begin, const_iterator end,
typename traits::value_type* output) {
*output = 0;
if (begin == end) {
return false;
}
// Note: no performance difference was found when using template
// specialization to remove this check in bases other than 16
if (traits::kBase == 16 && end - begin > 2 && *begin == '0' &&
(*(begin + 1) == 'x' || *(begin + 1) == 'X')) {
begin += 2;
}
for (const_iterator current = begin; current != end; ++current) {
uint8 new_digit = 0;
if (!CharToDigit<traits::kBase>(*current, &new_digit)) {
return false;
}
if (current != begin) {
if (!Sign::CheckBounds(output, new_digit)) {
return false;
}
*output *= traits::kBase;
}
Sign::Increment(new_digit, output);
}
return true;
}
};
class Positive : public Base<Positive> {
public:
static bool CheckBounds(value_type* output, uint8 new_digit) {
if (*output > static_cast<value_type>(traits::max() / traits::kBase) ||
(*output == static_cast<value_type>(traits::max() / traits::kBase) &&
new_digit > traits::max() % traits::kBase)) {
*output = traits::max();
return false;
}
return true;
}
static void Increment(uint8 increment, value_type* output) {
*output += increment;
}
};
class Negative : public Base<Negative> {
public:
static bool CheckBounds(value_type* output, uint8 new_digit) {
if (*output < traits::min() / traits::kBase ||
(*output == traits::min() / traits::kBase &&
new_digit > 0 - traits::min() % traits::kBase)) {
*output = traits::min();
return false;
}
return true;
}
static void Increment(uint8 increment, value_type* output) {
*output -= increment;
}
};
};
template<typename ITERATOR, typename VALUE, int BASE>
class BaseIteratorRangeToNumberTraits {
public:
typedef ITERATOR iterator_type;
typedef VALUE value_type;
static value_type min() {
return std::numeric_limits<value_type>::min();
}
static value_type max() {
return std::numeric_limits<value_type>::max();
}
static const int kBase = BASE;
};
template<typename ITERATOR>
class BaseHexIteratorRangeToIntTraits
: public BaseIteratorRangeToNumberTraits<ITERATOR, int, 16> {
public:
// Allow parsing of 0xFFFFFFFF, which is technically an overflow
static unsigned int max() {
return std::numeric_limits<unsigned int>::max();
}
};
typedef BaseHexIteratorRangeToIntTraits<StringPiece::const_iterator>
HexIteratorRangeToIntTraits;
template <typename ITERATOR>
class BaseHexIteratorRangeToUIntTraits
: public BaseIteratorRangeToNumberTraits<ITERATOR, unsigned int, 16> {};
typedef BaseHexIteratorRangeToUIntTraits<StringPiece::const_iterator>
HexIteratorRangeToUIntTraits;
template<typename STR>
bool HexStringToBytesT(const STR& input, std::vector<uint8>* output) {
DCHECK_EQ(output->size(), 0u);
size_t count = input.size();
if (count == 0 || (count % 2) != 0)
return false;
for (uintptr_t i = 0; i < count / 2; ++i) {
uint8 msb = 0; // most significant 4 bits
uint8 lsb = 0; // least significant 4 bits
if (!CharToDigit<16>(input[i * 2], &msb) ||
!CharToDigit<16>(input[i * 2 + 1], &lsb))
return false;
output->push_back((msb << 4) | lsb);
}
return true;
}
template <typename VALUE, int BASE>
class StringPieceToNumberTraits
: public BaseIteratorRangeToNumberTraits<StringPiece::const_iterator,
VALUE,
BASE> {};
template <typename VALUE>
bool StringToIntImpl(const StringPiece& input, VALUE* output) {
return IteratorRangeToNumber<StringPieceToNumberTraits<VALUE, 10> >::Invoke(
input.begin(), input.end(), output);
}
template <typename VALUE, int BASE>
class StringPiece16ToNumberTraits
: public BaseIteratorRangeToNumberTraits<StringPiece16::const_iterator,
VALUE,
BASE> {};
template <typename VALUE>
bool String16ToIntImpl(const StringPiece16& input, VALUE* output) {
return IteratorRangeToNumber<StringPiece16ToNumberTraits<VALUE, 10> >::Invoke(
input.begin(), input.end(), output);
}
} // namespace
#define DEFINE_INTEGRAL_TO_STRING_CONVERSIONS(Name, CppType) \
std::string Name##ToString(CppType value) { \
return IntToStringT<std::string, CppType>::IntToString(value); \
} \
string16 Name##ToString16(CppType value) { \
return IntToStringT<string16, CppType>::IntToString(value); \
}
INTEGRAL_STRING_CONVERSIONS_FOR_EACH(DEFINE_INTEGRAL_TO_STRING_CONVERSIONS)
#undef DEFINE_INTEGRAL_TO_STRING_CONVERSIONS
std::string DoubleToString(double value) {
// According to g_fmt.cc, it is sufficient to declare a buffer of size 32.
char buffer[32];
dmg_fp::g_fmt(buffer, value);
return std::string(buffer);
}
#define DEFINE_STRING_TO_INTEGRAL_CONVERSIONS(Name, CppType) \
bool StringTo##Name(const StringPiece& input, CppType* output) { \
return StringToIntImpl(input, output); \
} \
bool StringTo##Name(const StringPiece16& input, CppType* output) { \
return String16ToIntImpl(input, output); \
}
INTEGRAL_STRING_CONVERSIONS_FOR_EACH(DEFINE_STRING_TO_INTEGRAL_CONVERSIONS)
#undef DEFINE_STRING_TO_INTEGRAL_CONVERSIONS
bool StringToDouble(const std::string& input, double* output) {
errno = 0; // Thread-safe? It is on at least Mac, Linux, and Windows.
char* endptr = NULL;
*output = dmg_fp::strtod(input.c_str(), &endptr);
// Cases to return false:
// - If errno is ERANGE, there was an overflow or underflow.
// - If the input string is empty, there was nothing to parse.
// - If endptr does not point to the end of the string, there are either
// characters remaining in the string after a parsed number, or the string
// does not begin with a parseable number. endptr is compared to the
// expected end given the string's stated length to correctly catch cases
// where the string contains embedded NUL characters.
// - If the first character is a space, there was leading whitespace
return errno == 0 &&
!input.empty() &&
input.c_str() + input.length() == endptr &&
!isspace(input[0]);
}
// Note: if you need to add String16ToDouble, first ask yourself if it's
// really necessary. If it is, probably the best implementation here is to
// convert to 8-bit and then use the 8-bit version.
// Note: if you need to add an iterator range version of StringToDouble, first
// ask yourself if it's really necessary. If it is, probably the best
// implementation here is to instantiate a string and use the string version.
std::string HexEncode(const void* bytes, size_t size) {
static const char kHexChars[] = "0123456789ABCDEF";
// Each input byte creates two output hex characters.
std::string ret(size * 2, '\0');
for (size_t i = 0; i < size; ++i) {
char b = reinterpret_cast<const char*>(bytes)[i];
ret[(i * 2)] = kHexChars[(b >> 4) & 0xf];
ret[(i * 2) + 1] = kHexChars[b & 0xf];
}
return ret;
}
bool HexStringToInt(const StringPiece& input, int* output) {
return IteratorRangeToNumber<HexIteratorRangeToIntTraits>::Invoke(
input.begin(), input.end(), output);
}
bool HexStringToUInt(const StringPiece& input, unsigned int* output) {
return IteratorRangeToNumber<HexIteratorRangeToUIntTraits>::Invoke(
input.begin(), input.end(), output);
}
bool HexStringToBytes(const std::string& input, std::vector<uint8>* output) {
return HexStringToBytesT(input, output);
}
} // namespace base