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Diffstat (limited to 'base/string_number_conversions.cc')
-rw-r--r-- | base/string_number_conversions.cc | 545 |
1 files changed, 545 insertions, 0 deletions
diff --git a/base/string_number_conversions.cc b/base/string_number_conversions.cc new file mode 100644 index 000000000000..54eca17511c1 --- /dev/null +++ b/base/string_number_conversions.cc @@ -0,0 +1,545 @@ +// Copyright (c) 2011 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/logging.h" +#include "base/third_party/dmg_fp/dmg_fp.h" +#include "base/utf_string_conversions.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 (!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; +}; + +typedef BaseIteratorRangeToNumberTraits<std::string::const_iterator, int, 10> + IteratorRangeToIntTraits; +typedef BaseIteratorRangeToNumberTraits<string16::const_iterator, int, 10> + WideIteratorRangeToIntTraits; +typedef BaseIteratorRangeToNumberTraits<std::string::const_iterator, int64, 10> + IteratorRangeToInt64Traits; +typedef BaseIteratorRangeToNumberTraits<string16::const_iterator, int64, 10> + WideIteratorRangeToInt64Traits; + +typedef BaseIteratorRangeToNumberTraits<const char*, int, 10> + CharBufferToIntTraits; +typedef BaseIteratorRangeToNumberTraits<const char16*, int, 10> + WideCharBufferToIntTraits; +typedef BaseIteratorRangeToNumberTraits<const char*, int64, 10> + CharBufferToInt64Traits; +typedef BaseIteratorRangeToNumberTraits<const char16*, int64, 10> + WideCharBufferToInt64Traits; + +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<std::string::const_iterator> + HexIteratorRangeToIntTraits; +typedef BaseHexIteratorRangeToIntTraits<const char*> + HexCharBufferToIntTraits; + +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; +} + +} // 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 std::string& input, int* output) { + return IteratorRangeToNumber<IteratorRangeToIntTraits>::Invoke(input.begin(), + input.end(), + output); +} + +bool StringToInt(std::string::const_iterator begin, + std::string::const_iterator end, + int* output) { + return IteratorRangeToNumber<IteratorRangeToIntTraits>::Invoke(begin, + end, + output); +} + +#if !defined(STD_STRING_ITERATOR_IS_CHAR_POINTER) +bool StringToInt(const char* begin, const char* end, int* output) { + return IteratorRangeToNumber<CharBufferToIntTraits>::Invoke(begin, + end, + output); +} +#endif + +bool StringToInt(const string16& input, int* output) { + return IteratorRangeToNumber<WideIteratorRangeToIntTraits>::Invoke( + input.begin(), input.end(), output); +} + +bool StringToInt(string16::const_iterator begin, + string16::const_iterator end, + int* output) { + return IteratorRangeToNumber<WideIteratorRangeToIntTraits>::Invoke(begin, + end, + output); +} + +#if !defined(BASE_STRING16_ITERATOR_IS_CHAR16_POINTER) +bool StringToInt(const char16* begin, const char16* end, int* output) { + return IteratorRangeToNumber<WideCharBufferToIntTraits>::Invoke(begin, + end, + output); +} +#endif + +bool StringToInt64(const std::string& input, int64* output) { + return IteratorRangeToNumber<IteratorRangeToInt64Traits>::Invoke( + input.begin(), input.end(), output); +} + +bool StringToInt64(std::string::const_iterator begin, + std::string::const_iterator end, + int64* output) { + return IteratorRangeToNumber<IteratorRangeToInt64Traits>::Invoke(begin, + end, + output); +} + +#if !defined(STD_STRING_ITERATOR_IS_CHAR_POINTER) +bool StringToInt64(const char* begin, const char* end, int64* output) { + return IteratorRangeToNumber<CharBufferToInt64Traits>::Invoke(begin, + end, + output); +} +#endif + +bool StringToInt64(const string16& input, int64* output) { + return IteratorRangeToNumber<WideIteratorRangeToInt64Traits>::Invoke( + input.begin(), input.end(), output); +} + +bool StringToInt64(string16::const_iterator begin, + string16::const_iterator end, + int64* output) { + return IteratorRangeToNumber<WideIteratorRangeToInt64Traits>::Invoke(begin, + end, + output); +} + +#if !defined(BASE_STRING16_ITERATOR_IS_CHAR16_POINTER) +bool StringToInt64(const char16* begin, const char16* end, int64* output) { + return IteratorRangeToNumber<WideCharBufferToInt64Traits>::Invoke(begin, + end, + output); +} +#endif + +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 std::string& input, int* output) { + return IteratorRangeToNumber<HexIteratorRangeToIntTraits>::Invoke( + input.begin(), input.end(), output); +} + +bool HexStringToInt(std::string::const_iterator begin, + std::string::const_iterator end, + int* output) { + return IteratorRangeToNumber<HexIteratorRangeToIntTraits>::Invoke(begin, + end, + output); +} + +#if !defined(STD_STRING_ITERATOR_IS_CHAR_POINTER) +bool HexStringToInt(const char* begin, const char* end, int* output) { + return IteratorRangeToNumber<HexCharBufferToIntTraits>::Invoke(begin, + end, + output); +} +#endif + +bool HexStringToBytes(const std::string& input, std::vector<uint8>* output) { + return HexStringToBytesT(input, output); +} + +} // namespace base |