text: // Copyright 2010 the V8 project authors. All rights reserved.
  // Redistribution and use in source and binary forms, with or without
  // modification, are permitted provided that the following conditions are
  // met:
  //
  //     * Redistributions of source code must retain the above copyright
  //       notice, this list of conditions and the following disclaimer.
  //     * Redistributions in binary form must reproduce the above
  //       copyright notice, this list of conditions and the following
  //       disclaimer in the documentation and/or other materials provided
  //       with the distribution.
  //     * Neither the name of Google Inc. nor the names of its
  //       contributors may be used to endorse or promote products derived
  //       from this software without specific prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  #ifndef DOUBLE_CONVERSION_UTILS_H_
  #define DOUBLE_CONVERSION_UTILS_H_
  
  #include <stdlib.h>
  #include <string.h>
  
  #include <assert.h>
  #ifndef ASSERT
  #define ASSERT(condition)      (assert(condition))
  #endif
  #ifndef UNIMPLEMENTED
  #define UNIMPLEMENTED() (abort())
  #endif
  #ifndef UNREACHABLE
  #define UNREACHABLE()   (abort())
  #endif
  
  // Double operations detection based on target architecture.
  // Linux uses a 80bit wide floating point stack on x86. This induces double
  // rounding, which in turn leads to wrong results.
  // An easy way to test if the floating-point operations are correct is to
  // evaluate: 89255.0/1e22. If the floating-point stack is 64 bits wide then
  // the result is equal to 89255e-22.
  // The best way to test this, is to create a division-function and to compare
  // the output of the division with the expected result. (Inlining must be
  // disabled.)
  // On Linux,x86 89255e-22 != Div_double(89255.0/1e22)
  #if defined(_M_X64) || defined(__x86_64__) || \
      defined(__ARMEL__) || defined(__avr32__) || \
      defined(__hppa__) || defined(__ia64__) || \
      defined(__mips__) || defined(__powerpc__) || \
      defined(__sparc__) || defined(__sparc) || defined(__s390__) || \
      defined(__SH4__) || defined(__alpha__) || \
      defined(_MIPS_ARCH_MIPS32R2) || defined(__aarch64__)
  #define DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS 1
  #elif defined(_M_IX86) || defined(__i386__) || defined(__i386)
  #if defined(_WIN32)
  // Windows uses a 64bit wide floating point stack.
  #define DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS 1
  #else
  #undef DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS
  #endif  // _WIN32
  #else
  #error Target architecture was not detected as supported by Double-Conversion.
  #endif
  
  
  #if defined(_WIN32) && !defined(__MINGW32__)
  
  typedef signed char int8_t;
  typedef unsigned char uint8_t;
  typedef short int16_t;  // NOLINT
  typedef unsigned short uint16_t;  // NOLINT
  typedef int int32_t;
  typedef unsigned int uint32_t;
  typedef __int64 int64_t;
  typedef unsigned __int64 uint64_t;
  // intptr_t and friends are defined in crtdefs.h through stdio.h.
  
  #else
  
  #include <stdint.h>
  
  #endif
  
  // The following macro works on both 32 and 64-bit platforms.
  // Usage: instead of writing 0x1234567890123456
  //      write UINT64_2PART_C(0x12345678,90123456);
  #define UINT64_2PART_C(a, b) (((static_cast<uint64_t>(a) << 32) + 0x##b##u))
  
  
  // The expression ARRAY_SIZE(a) is a compile-time constant of type
  // size_t which represents the number of elements of the given
  // array. You should only use ARRAY_SIZE on statically allocated
  // arrays.
  #ifndef ARRAY_SIZE
  #define ARRAY_SIZE(a)                                   \
    ((sizeof(a) / sizeof(*(a))) /                         \
    static_cast<size_t>(!(sizeof(a) % sizeof(*(a)))))
  #endif
  
  // A macro to disallow the evil copy constructor and operator= functions
  // This should be used in the private: declarations for a class
  #ifndef DISALLOW_COPY_AND_ASSIGN
  #define DISALLOW_COPY_AND_ASSIGN(TypeName)      \
    TypeName(const TypeName&);                    \
    void operator=(const TypeName&)
  #endif
  
  // A macro to disallow all the implicit constructors, namely the
  // default constructor, copy constructor and operator= functions.
  //
  // This should be used in the private: declarations for a class
  // that wants to prevent anyone from instantiating it. This is
  // especially useful for classes containing only static methods.
  #ifndef DISALLOW_IMPLICIT_CONSTRUCTORS
  #define DISALLOW_IMPLICIT_CONSTRUCTORS(TypeName) \
    TypeName();                                    \
    DISALLOW_COPY_AND_ASSIGN(TypeName)
  #endif
  
  namespace double_conversion {
  
  static const int kCharSize = sizeof(char);
  
  // Returns the maximum of the two parameters.
  template <typename T>
  static T Max(T a, T b) {
    return a < b ? b : a;
  }
  
  
  // Returns the minimum of the two parameters.
  template <typename T>
  static T Min(T a, T b) {
    return a < b ? a : b;
  }
  
  
  inline int StrLength(const char* string) {
    size_t length = strlen(string);
    ASSERT(length == static_cast<size_t>(static_cast<int>(length)));
    return static_cast<int>(length);
  }
  
  // This is a simplified version of V8's Vector class.
  template <typename T>
  class Vector {
   public:
    Vector() : start_(NULL), length_(0) {}
    Vector(T* data, int length) : start_(data), length_(length) {
      ASSERT(length == 0 || (length > 0 && data != NULL));
    }
  
    // Returns a vector using the same backing storage as this one,
    // spanning from and including 'from', to but not including 'to'.
    Vector<T> SubVector(int from, int to) {
      ASSERT(to <= length_);
      ASSERT(from < to);
      ASSERT(0 <= from);
      return Vector<T>(start() + from, to - from);
    }
  
    // Returns the length of the vector.
    int length() const { return length_; }
  
    // Returns whether or not the vector is empty.
    bool is_empty() const { return length_ == 0; }
  
    // Returns the pointer to the start of the data in the vector.
    T* start() const { return start_; }
  
    // Access individual vector elements - checks bounds in debug mode.
    T& operator[](int index) const {
      ASSERT(0 <= index && index < length_);
      return start_[index];
    }
  
    T& first() { return start_[0]; }
  
    T& last() { return start_[length_ - 1]; }
  
   private:
    T* start_;
    int length_;
  };
  
  
  // Helper class for building result strings in a character buffer. The
  // purpose of the class is to use safe operations that checks the
  // buffer bounds on all operations in debug mode.
  class StringBuilder {
   public:
    StringBuilder(char* buffer, int size)
        : buffer_(buffer, size), position_(0) { }
  
    ~StringBuilder() { if (!is_finalized()) Finalize(); }
  
    int size() const { return buffer_.length(); }
  
    // Get the current position in the builder.
    int position() const {
      ASSERT(!is_finalized());
      return position_;
    }
  
    // Reset the position.
    void Reset() { position_ = 0; }
  
    // Add a single character to the builder. It is not allowed to add
    // 0-characters; use the Finalize() method to terminate the string
    // instead.
    void AddCharacter(char c) {
      // I just extract raw data not a cstr so null is fine.
      //ASSERT(c != '\0');
      ASSERT(!is_finalized() && position_ < buffer_.length());
      buffer_[position_++] = c;
    }
  
    // Add an entire string to the builder. Uses strlen() internally to
    // compute the length of the input string.
    void AddString(const char* s) {
      AddSubstring(s, StrLength(s));
    }
  
    // Add the first 'n' characters of the given string 's' to the
    // builder. The input string must have enough characters.
    void AddSubstring(const char* s, int n) {
      ASSERT(!is_finalized() && position_ + n < buffer_.length());
      // I just extract raw data not a cstr so null is fine.
      //ASSERT(static_cast<size_t>(n) <= strlen(s));
      memmove(&buffer_[position_], s, n * kCharSize);
      position_ += n;
    }
  
  
    // Add character padding to the builder. If count is non-positive,
    // nothing is added to the builder.
    void AddPadding(char c, int count) {
      for (int i = 0; i < count; i++) {
        AddCharacter(c);
      }
    }
  
    // Finalize the string by 0-terminating it and returning the buffer.
    char* Finalize() {
      ASSERT(!is_finalized() && position_ < buffer_.length());
      buffer_[position_] = '\0';
      // Make sure nobody managed to add a 0-character to the
      // buffer while building the string.
      // I just extract raw data not a cstr so null is fine.
      //ASSERT(strlen(buffer_.start()) == static_cast<size_t>(position_));
      position_ = -1;
      ASSERT(is_finalized());
      return buffer_.start();
    }
  
   private:
    Vector<char> buffer_;
    int position_;
  
    bool is_finalized() const { return position_ < 0; }
  
    DISALLOW_IMPLICIT_CONSTRUCTORS(StringBuilder);
  };
  
  // The type-based aliasing rule allows the compiler to assume that pointers of
  // different types (for some definition of different) never alias each other.
  // Thus the following code does not work:
  //
  // float f = foo();
  // int fbits = *(int*)(&f);
  //
  // The compiler 'knows' that the int pointer can't refer to f since the types
  // don't match, so the compiler may cache f in a register, leaving random data
  // in fbits.  Using C++ style casts makes no difference, however a pointer to
  // char data is assumed to alias any other pointer.  This is the 'memcpy
  // exception'.
  //
  // Bit_cast uses the memcpy exception to move the bits from a variable of one
  // type of a variable of another type.  Of course the end result is likely to
  // be implementation dependent.  Most compilers (gcc-4.2 and MSVC 2005)
  // will completely optimize BitCast away.
  //
  // There is an additional use for BitCast.
  // Recent gccs will warn when they see casts that may result in breakage due to
  // the type-based aliasing rule.  If you have checked that there is no breakage
  // you can use BitCast to cast one pointer type to another.  This confuses gcc
  // enough that it can no longer see that you have cast one pointer type to
  // another thus avoiding the warning.
  template <class Dest, class Source>
  inline Dest BitCast(const Source& source) {
    // Compile time assertion: sizeof(Dest) == sizeof(Source)
    // A compile error here means your Dest and Source have different sizes.
    typedef char VerifySizesAreEqual[sizeof(Dest) == sizeof(Source) ? 1 : -1]
  #if __GNUC__ > 4 || __GNUC__ == 4 && __GNUC_MINOR__ >= 8
        __attribute__((unused))
  #endif
        ;
  
    Dest dest;
    memmove(&dest, &source, sizeof(dest));
    return dest;
  }
  
  template <class Dest, class Source>
  inline Dest BitCast(Source* source) {
    return BitCast<Dest>(reinterpret_cast<uintptr_t>(source));
  }
  
  }  // namespace double_conversion
  
  #endif  // DOUBLE_CONVERSION_UTILS_H_
  