Move the number conversions from string_util to a new file....

base/string_number_conversions.cc

+// Copyright (c) 2010 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 <errno.h>
+#include <stdlib.h>
+
+#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();
+  }
+};
+
+// Generalized string-to-number conversion.
+//
+// StringToNumberTraits should provide:
+//  - a typedef for string_type, the STL string type used as input.
+//  - a typedef for value_type, the target numeric type.
+//  - a static function, convert_func, which dispatches to an appropriate
+//    strtol-like function and returns type value_type.
+//  - a static function, valid_func, which validates |input| and returns a bool
+//    indicating whether it is in proper form.  This is used to check for
+//    conditions that convert_func tolerates but should result in
+//    StringToNumber returning false.  For strtol-like funtions, valid_func
+//    should check for leading whitespace.
+template<typename StringToNumberTraits>
+bool StringToNumber(const typename StringToNumberTraits::string_type& input,
+                    typename StringToNumberTraits::value_type* output) {
+  typedef StringToNumberTraits traits;
+
+  errno = 0;  // Thread-safe?  It is on at least Mac, Linux, and Windows.
+  typename traits::string_type::value_type* endptr = NULL;
+  typename traits::value_type value = traits::convert_func(input.c_str(),
+                                                           &endptr);
+  *output = value;
+
+  // 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.
+  //  - valid_func determines that the input is not in preferred form.
+  return errno == 0 &&
+         !input.empty() &&
+         input.c_str() + input.length() == endptr &&
+         traits::valid_func(input);
+}
+
+static int strtoi(const char *nptr, char **endptr, int base) {
+  long res = strtol(nptr, endptr, base);
+#if __LP64__
+  // Long is 64-bits, we have to handle under/overflow ourselves.
+  if (res > kint32max) {
+    res = kint32max;
+    errno = ERANGE;
+  } else if (res < kint32min) {
+    res = kint32min;
+    errno = ERANGE;
+  }
+#endif
+  return static_cast<int>(res);
+}
+
+static unsigned int strtoui(const char *nptr, char **endptr, int base) {
+  unsigned long res = strtoul(nptr, endptr, base);
+#if __LP64__
+  // Long is 64-bits, we have to handle under/overflow ourselves.  Test to see
+  // if the result can fit into 32-bits (as signed or unsigned).
+  if (static_cast<int>(static_cast<long>(res)) != static_cast<long>(res) &&
+      static_cast<unsigned int>(res) != res) {
+    res = kuint32max;
+    errno = ERANGE;
+  }
+#endif
+  return static_cast<unsigned int>(res);
+}
+
+class StringToIntTraits {
+ public:
+  typedef std::string string_type;
+  typedef int value_type;
+  static const int kBase = 10;
+  static inline value_type convert_func(const string_type::value_type* str,
+                                        string_type::value_type** endptr) {
+    return strtoi(str, endptr, kBase);
+  }
+  static inline bool valid_func(const string_type& str) {
+    return !str.empty() && !isspace(str[0]);
+  }
+};
+
+class String16ToIntTraits {
+ public:
+  typedef string16 string_type;
+  typedef int value_type;
+  static const int kBase = 10;
+  static inline value_type convert_func(const string_type::value_type* str,
+                                        string_type::value_type** endptr) {
+#if defined(WCHAR_T_IS_UTF16)
+    return wcstol(str, endptr, kBase);
+#elif defined(WCHAR_T_IS_UTF32)
+    std::string ascii_string = UTF16ToUTF8(string16(str));
+    char* ascii_end = NULL;
+    value_type ret = strtoi(ascii_string.c_str(), &ascii_end, kBase);
+    if (ascii_string.c_str() + ascii_string.length() == ascii_end) {
+      *endptr =
+          const_cast<string_type::value_type*>(str) + ascii_string.length();
+    }
+    return ret;
+#endif
+  }
+  static inline bool valid_func(const string_type& str) {
+    return !str.empty() && !iswspace(str[0]);
+  }
+};
+
+class StringToInt64Traits {
+ public:
+  typedef std::string string_type;
+  typedef int64 value_type;
+  static const int kBase = 10;
+  static inline value_type convert_func(const string_type::value_type* str,
+                                        string_type::value_type** endptr) {
+#ifdef OS_WIN
+    return _strtoi64(str, endptr, kBase);
+#else  // assume OS_POSIX
+    return strtoll(str, endptr, kBase);
+#endif
+  }
+  static inline bool valid_func(const string_type& str) {
+    return !str.empty() && !isspace(str[0]);
+  }
+};
+
+class String16ToInt64Traits {
+ public:
+  typedef string16 string_type;
+  typedef int64 value_type;
+  static const int kBase = 10;
+  static inline value_type convert_func(const string_type::value_type* str,
+                                        string_type::value_type** endptr) {
+#ifdef OS_WIN
+    return _wcstoi64(str, endptr, kBase);
+#else  // assume OS_POSIX
+    std::string ascii_string = UTF16ToUTF8(string16(str));
+    char* ascii_end = NULL;
+    value_type ret = strtoll(ascii_string.c_str(), &ascii_end, kBase);
+    if (ascii_string.c_str() + ascii_string.length() == ascii_end) {
+      *endptr =
+          const_cast<string_type::value_type*>(str) + ascii_string.length();
+    }
+    return ret;
+#endif
+  }
+  static inline bool valid_func(const string_type& str) {
+    return !str.empty() && !iswspace(str[0]);
+  }
+};
+
+// For the HexString variants, use the unsigned variants like strtoul for
+// convert_func so that input like "0x80000000" doesn't result in an overflow.
+
+class HexStringToIntTraits {
+ public:
+  typedef std::string string_type;
+  typedef int value_type;
+  static const int kBase = 16;
+  static inline value_type convert_func(const string_type::value_type* str,
+                                        string_type::value_type** endptr) {
+    return strtoui(str, endptr, kBase);
+  }
+  static inline bool valid_func(const string_type& str) {
+    return !str.empty() && !isspace(str[0]);
+  }
+};
+
+class StringToDoubleTraits {
+ public:
+  typedef std::string string_type;
+  typedef double value_type;
+  static inline value_type convert_func(const string_type::value_type* str,
+                                        string_type::value_type** endptr) {
+    return dmg_fp::strtod(str, endptr);
+  }
+  static inline bool valid_func(const string_type& str) {
+    return !str.empty() && !isspace(str[0]);
+  }
+};
+
+template<class CHAR>
+bool HexDigitToIntT(const CHAR digit, uint8* val) {
+  if (digit >= '0' && digit <= '9')
+    *val = digit - '0';
+  else if (digit >= 'a' && digit <= 'f')
+    *val = 10 + digit - 'a';
+  else if (digit >= 'A' && digit <= 'F')
+    *val = 10 + digit - 'A';
+  else
+    return false;
+  return true;
+}
+
+template<typename STR>
+bool HexStringToBytesT(const STR& input, std::vector<uint8>* output) {
+  DCHECK(output->size() == 0);
+  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 (!HexDigitToIntT(input[i * 2], &msb) ||
+        !HexDigitToIntT(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 StringToNumber<StringToIntTraits>(input, output);
+}
+
+bool StringToInt(const string16& input, int* output) {
+  return StringToNumber<String16ToIntTraits>(input, output);
+}
+
+bool StringToInt64(const std::string& input, int64* output) {
+  return StringToNumber<StringToInt64Traits>(input, output);
+}
+
+bool StringToInt64(const string16& input, int64* output) {
+  return StringToNumber<String16ToInt64Traits>(input, output);
+}
+
+bool StringToDouble(const std::string& input, double* output) {
+  return StringToNumber<StringToDoubleTraits>(input, output);
+}
+
+// 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.
+
+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 StringToNumber<HexStringToIntTraits>(input, output);
+}
+
+bool HexStringToBytes(const std::string& input, std::vector<uint8>* output) {
+  return HexStringToBytesT(input, output);
+}
+
+}  // namespace base