// 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 "wtf/Assertions.h"
#include <string.h>
#define UNIMPLEMENTED ASSERT_NOT_REACHED
#define UNREACHABLE ASSERT_NOT_REACHED
// 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(__aarch64__) || \
defined(__MIPSEL__)
#define DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS 1
#elif defined(_M_IX86) || 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.
#define ARRAY_SIZE(a) \
((sizeof(a) / sizeof(*(a))) / \
static_cast<size_t>(!(sizeof(a) % sizeof(*(a)))))
// A macro to disallow the evil copy constructor and operator= functions
// This should be used in the private: declarations for a class
#define DISALLOW_COPY_AND_ASSIGN(TypeName) \
TypeName(const TypeName&); \
void operator=(const TypeName&)
// 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.
#define DISALLOW_IMPLICIT_CONSTRUCTORS(TypeName) \
TypeName(); \
DISALLOW_COPY_AND_ASSIGN(TypeName)
namespace WTF {
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_;
}
// Set the current position in the builder.
void SetPosition(int position)
{
ASSERT(!is_finalized());
ASSERT_WITH_SECURITY_IMPLICATION(position < size());
position_ = 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) {
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());
ASSERT_WITH_SECURITY_IMPLICATION(static_cast<size_t>(n) <= strlen(s));
memcpy(&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.
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];
Dest dest;
memcpy(&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
} // namespace WTF
#endif // DOUBLE_CONVERSION_UTILS_H_