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Use C++11 features to simplify QIntC

This commit is contained in:
Jay Berkenbilt 2020-04-03 12:05:50 -04:00
parent a6f1f829db
commit 8a87a2fbee
1 changed files with 7 additions and 49 deletions
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56
include/qpdf/QIntC.hh
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@ -29,60 +29,20 @@
#include <limits>
#include <sstream>
#include <cassert>
#include <type_traits>
// This namespace provides safe integer conversion that detects
// overflows. It uses short, cryptic names for brevity.
namespace QIntC // QIntC = qpdf Integer Conversion
{
// Create templates to get the unsigned version of integer types.
// With C++11, we could use std::make_unsigned, but qpdf, at least
// for now, supports pre-c++11 compilers.
// to_u is here for backward-compatibility from before we required
// C++-11.
template <typename T>
class to_u
{
};
template <>
class to_u<char>
{
public:
typedef unsigned char type;
};
template <>
class to_u<signed char>
{
public:
typedef unsigned char type;
};
template <>
class to_u<short>
{
public:
typedef unsigned short type;
};
template <>
class to_u<int>
{
public:
typedef unsigned int type;
};
template <>
class to_u<long>
{
public:
typedef unsigned long type;
};
template <>
class to_u<long long>
{
public:
typedef unsigned long long type;
typedef typename std::make_unsigned<T>::type type;
};
// Basic IntConverter class, which converts an integer from the
@ -147,8 +107,7 @@ namespace QIntC // QIntC = qpdf Integer Conversion
// From is signed, and To is unsigned. If i > 0, it's safe to
// convert it to the corresponding unsigned type and to
// compare with To's max.
typename to_u<From>::type ii =
static_cast<typename to_u<From>::type>(i);
auto ii = static_cast<typename to_u<From>::type>(i);
if ((i < 0) || (ii > std::numeric_limits<To>::max()))
{
std::ostringstream msg;
@ -170,9 +129,8 @@ namespace QIntC // QIntC = qpdf Integer Conversion
{
// From is unsigned, and to is signed. Convert To's max to the
// unsigned version of To and compare i against that.
typename to_u<To>::type maxval =
static_cast<typename to_u<To>::type>(
std::numeric_limits<To>::max());
auto maxval = static_cast<typename to_u<To>::type>(
std::numeric_limits<To>::max());
if (i > maxval)
{
std::ostringstream msg;