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 // 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