/external/chromium_org/base/strings/string_number_conversions.cc
C++ | 516 lines | 374 code | 82 blank | 60 comment | 64 complexity | b589e9bb2652db713879906d4c0eda8c MD5 | raw file
- // 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/strings/string_number_conversions.h"
- #include <ctype.h>
- #include <errno.h>
- #include <stdlib.h>
- #include <wctype.h>
- #include <limits>
- #include "base/logging.h"
- #include "base/scoped_clear_errno.h"
- #include "base/strings/utf_string_conversions.h"
- #include "base/third_party/dmg_fp/dmg_fp.h"
- namespace base {
- namespace {
- template <typename STR, typename INT, typename UINT, bool NEG>
- struct IntToStringT {
- // This is to avoid a compiler warning about unary minus on unsigned type.
- // For example, say you had the following code:
- // template <typename INT>
- // INT abs(INT value) { return value < 0 ? -value : value; }
- // Even though if INT is unsigned, it's impossible for value < 0, so the
- // unary minus will never be taken, the compiler will still generate a
- // warning. We do a little specialization dance...
- template <typename INT2, typename UINT2, bool NEG2>
- struct ToUnsignedT {};
- template <typename INT2, typename UINT2>
- struct ToUnsignedT<INT2, UINT2, false> {
- static UINT2 ToUnsigned(INT2 value) {
- return static_cast<UINT2>(value);
- }
- };
- template <typename INT2, typename UINT2>
- struct ToUnsignedT<INT2, UINT2, true> {
- static UINT2 ToUnsigned(INT2 value) {
- return static_cast<UINT2>(value < 0 ? -value : value);
- }
- };
- // This set of templates is very similar to the above templates, but
- // for testing whether an integer is negative.
- template <typename INT2, bool NEG2>
- struct TestNegT {};
- template <typename INT2>
- struct TestNegT<INT2, false> {
- static bool TestNeg(INT2 value) {
- // value is unsigned, and can never be negative.
- return false;
- }
- };
- template <typename INT2>
- struct TestNegT<INT2, true> {
- static bool TestNeg(INT2 value) {
- return value < 0;
- }
- };
- 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);
- bool is_neg = TestNegT<INT, NEG>::TestNeg(value);
- // Even though is_neg will never be true when INT is parameterized as
- // unsigned, even the presence of the unary operation causes a warning.
- UINT res = ToUnsignedT<INT, UINT, NEG>::ToUnsigned(value);
- for (typename STR::iterator it = outbuf.end();;) {
- --it;
- DCHECK(it != outbuf.begin());
- *it = static_cast<typename STR::value_type>((res % 10) + '0');
- res /= 10;
- // We're done..
- if (res == 0) {
- if (is_neg) {
- --it;
- DCHECK(it != outbuf.begin());
- *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 (!std::numeric_limits<value_type>::is_signed) {
- valid = false;
- } else if (!Negative::Invoke(begin + 1, end, output)) {
- valid = false;
- }
- } 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> {
- };
- template<typename ITERATOR>
- class BaseHexIteratorRangeToInt64Traits
- : public BaseIteratorRangeToNumberTraits<ITERATOR, int64, 16> {
- };
- template<typename ITERATOR>
- class BaseHexIteratorRangeToUInt64Traits
- : public BaseIteratorRangeToNumberTraits<ITERATOR, uint64, 16> {
- };
- typedef BaseHexIteratorRangeToIntTraits<StringPiece::const_iterator>
- HexIteratorRangeToIntTraits;
- typedef BaseHexIteratorRangeToInt64Traits<StringPiece::const_iterator>
- HexIteratorRangeToInt64Traits;
- typedef BaseHexIteratorRangeToUInt64Traits<StringPiece::const_iterator>
- HexIteratorRangeToUInt64Traits;
- 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
- std::string IntToString(int value) {
- return IntToStringT<std::string, int, unsigned int, true>::
- IntToString(value);
- }
- string16 IntToString16(int value) {
- return IntToStringT<string16, int, unsigned int, true>::
- IntToString(value);
- }
- std::string UintToString(unsigned int value) {
- return IntToStringT<std::string, unsigned int, unsigned int, false>::
- IntToString(value);
- }
- string16 UintToString16(unsigned int value) {
- return IntToStringT<string16, unsigned int, unsigned int, false>::
- IntToString(value);
- }
- std::string Int64ToString(int64 value) {
- return IntToStringT<std::string, int64, uint64, true>::
- IntToString(value);
- }
- string16 Int64ToString16(int64 value) {
- return IntToStringT<string16, int64, uint64, true>::IntToString(value);
- }
- std::string Uint64ToString(uint64 value) {
- return IntToStringT<std::string, uint64, uint64, false>::
- IntToString(value);
- }
- string16 Uint64ToString16(uint64 value) {
- return IntToStringT<string16, uint64, uint64, false>::
- IntToString(value);
- }
- 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);
- }
- bool StringToInt(const StringPiece& input, int* output) {
- return StringToIntImpl(input, output);
- }
- bool StringToInt(const StringPiece16& input, int* output) {
- return String16ToIntImpl(input, output);
- }
- bool StringToUint(const StringPiece& input, unsigned* output) {
- return StringToIntImpl(input, output);
- }
- bool StringToUint(const StringPiece16& input, unsigned* output) {
- return String16ToIntImpl(input, output);
- }
- bool StringToInt64(const StringPiece& input, int64* output) {
- return StringToIntImpl(input, output);
- }
- bool StringToInt64(const StringPiece16& input, int64* output) {
- return String16ToIntImpl(input, output);
- }
- bool StringToUint64(const StringPiece& input, uint64* output) {
- return StringToIntImpl(input, output);
- }
- bool StringToUint64(const StringPiece16& input, uint64* output) {
- return String16ToIntImpl(input, output);
- }
- bool StringToSizeT(const StringPiece& input, size_t* output) {
- return StringToIntImpl(input, output);
- }
- bool StringToSizeT(const StringPiece16& input, size_t* output) {
- return String16ToIntImpl(input, output);
- }
- bool StringToDouble(const std::string& input, double* output) {
- // Thread-safe? It is on at least Mac, Linux, and Windows.
- ScopedClearErrno clear_errno;
- 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 HexStringToInt64(const StringPiece& input, int64* output) {
- return IteratorRangeToNumber<HexIteratorRangeToInt64Traits>::Invoke(
- input.begin(), input.end(), output);
- }
- bool HexStringToUInt64(const StringPiece& input, uint64* output) {
- return IteratorRangeToNumber<HexIteratorRangeToUInt64Traits>::Invoke(
- input.begin(), input.end(), output);
- }
- bool HexStringToBytes(const std::string& input, std::vector<uint8>* output) {
- return HexStringToBytesT(input, output);
- }
- } // namespace base