boost/spirit/core/primitives/impl/numerics.ipp
/*=============================================================================
Copyright (c) 1998-2003 Joel de Guzman
Copyright (c) 2001-2003 Hartmut Kaiser
http://spirit.sourceforge.net/
Use, modification and distribution is subject to the Boost Software
License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
http://www.boost.org/LICENSE_1_0.txt)
=============================================================================*/
#ifndef BOOST_SPIRIT_NUMERICS_IPP
#define BOOST_SPIRIT_NUMERICS_IPP
#include <cmath>
#if defined(BOOST_NO_STDC_NAMESPACE)
# define BOOST_SPIRIT_IMPL_STD_NS
#else
# define BOOST_SPIRIT_IMPL_STD_NS std
#endif
namespace boost { namespace spirit {
struct sign_parser; // forward declaration only
namespace impl
{
///////////////////////////////////////////////////////////////////////
//
// Extract the prefix sign (- or +)
//
///////////////////////////////////////////////////////////////////////
template <typename ScannerT>
bool
extract_sign(ScannerT const& scan, std::size_t& count)
{
// Extract the sign
count = 0;
bool neg = *scan == '-';
if (neg || (*scan == '+'))
{
++scan;
++count;
return neg;
}
return false;
}
///////////////////////////////////////////////////////////////////////
//
// Traits class for radix specific number conversion
//
// Test the validity of a single character:
//
// template<typename CharT> static bool is_valid(CharT ch);
//
// Convert a digit from character representation to binary
// representation:
//
// template<typename CharT> static int digit(CharT ch);
//
///////////////////////////////////////////////////////////////////////
template<const int Radix>
struct radix_traits;
////////////////////////////////// Binary
template<>
struct radix_traits<2>
{
template<typename CharT>
static bool is_valid(CharT ch)
{
return ('0' == ch || '1' == ch);
}
template<typename CharT>
static int digit(CharT ch)
{
return ch - '0';
}
};
////////////////////////////////// Octal
template<>
struct radix_traits<8>
{
template<typename CharT>
static bool is_valid(CharT ch)
{
return ('0' <= ch && ch <= '7');
}
template<typename CharT>
static int digit(CharT ch)
{
return ch - '0';
}
};
////////////////////////////////// Decimal
template<>
struct radix_traits<10>
{
template<typename CharT>
static bool is_valid(CharT ch)
{
return impl::isdigit_(ch);
}
template<typename CharT>
static int digit(CharT ch)
{
return ch - '0';
}
};
////////////////////////////////// Hexadecimal
template<>
struct radix_traits<16>
{
template<typename CharT>
static bool is_valid(CharT ch)
{
return impl::isxdigit_(ch);
}
template<typename CharT>
static int digit(CharT ch)
{
if (impl::isdigit_(ch))
return ch - '0';
return impl::tolower_(ch) - 'a' + 10;
}
};
///////////////////////////////////////////////////////////////////////
//
// Helper templates for encapsulation of radix specific
// conversion of an input string to an integral value.
//
// main entry point:
//
// extract_int<Radix, MinDigits, MaxDigits, Accumulate>
// ::f(first, last, n, count);
//
// The template parameter Radix represents the radix of the
// number contained in the parsed string. The template
// parameter MinDigits specifies the minimum digits to
// accept. The template parameter MaxDigits specifies the
// maximum digits to parse. A -1 value for MaxDigits will
// make it parse an arbitrarilly large number as long as the
// numeric type can hold it. Accumulate is either
// positive_accumulate<Radix> (default) for parsing positive
// numbers or negative_accumulate<Radix> otherwise.
//
// scan.first and scan.last are iterators as usual (i.e.
// first is mutable and is moved forward when a match is
// found), n is a variable that holds the number (passed by
// reference). The number of parsed characters is added to
// count (also passed by reference)
//
// NOTE:
// Returns a non-match, if the number to parse
// overflows (or underflows) the used integral type.
// Overflow (or underflow) is detected when an
// operation wraps a value from its maximum to its
// minimum (or vice-versa). For example, overflow
// occurs when the result of the expression n * x is
// less than n (assuming n is positive and x is
// greater than 1).
//
// BEWARE:
// the parameters 'n' and 'count' should be properly
// initialized before calling this function.
//
///////////////////////////////////////////////////////////////////////
template <int Radix>
struct positive_accumulate
{
// Use this accumulator if number is positive
template <typename T>
static bool check(T const& n, T const& prev)
{
return n < prev;
}
template <typename T, typename CharT>
static void add(T& n, CharT ch)
{
n += radix_traits<Radix>::digit(ch);
}
};
template <int Radix>
struct negative_accumulate
{
// Use this accumulator if number is negative
template <typename T>
static bool check(T const& n, T const& prev)
{
return n > prev;
}
template <typename T, typename CharT>
static void add(T& n, CharT ch)
{
n -= radix_traits<Radix>::digit(ch);
}
};
template <int Radix, typename Accumulate>
struct extract_int_base
{
// Common code for extract_int specializations
template <typename ScannerT, typename T>
static bool
f(ScannerT& scan, T& n)
{
T prev = n;
n *= Radix;
if (Accumulate::check(n, prev))
return false; // over/underflow!
prev = n;
Accumulate::add(n, *scan);
if (Accumulate::check(n, prev))
return false; // over/underflow!
return true;
}
};
template <bool Bounded>
struct extract_int_
{
template <
int Radix,
unsigned MinDigits,
int MaxDigits,
typename Accumulate
>
struct apply
{
typedef extract_int_base<Radix, Accumulate> base;
typedef radix_traits<Radix> check;
template <typename ScannerT, typename T>
static bool
f(ScannerT& scan, T& n, std::size_t& count)
{
std::size_t i = 0;
for (; (i < MaxDigits) && !scan.at_end()
&& check::is_valid(*scan);
++i, ++scan, ++count)
{
if (!base::f(scan, n))
return false; // over/underflow!
}
return i >= MinDigits;
}
};
};
template <>
struct extract_int_<false>
{
template <
int Radix,
unsigned MinDigits,
int MaxDigits,
typename Accumulate
>
struct apply
{
typedef extract_int_base<Radix, Accumulate> base;
typedef radix_traits<Radix> check;
template <typename ScannerT, typename T>
static bool
f(ScannerT& scan, T& n, std::size_t& count)
{
std::size_t i = 0;
for (; !scan.at_end() && check::is_valid(*scan);
++i, ++scan, ++count)
{
if (!base::f(scan, n))
return false; // over/underflow!
}
return i >= MinDigits;
}
};
};
//////////////////////////////////
template <
int Radix, unsigned MinDigits, int MaxDigits,
typename Accumulate = positive_accumulate<Radix>
>
struct extract_int
{
template <typename ScannerT, typename T>
static bool
f(ScannerT& scan, T& n, std::size_t& count)
{
typedef typename extract_int_<(MaxDigits >= 0)>::template
apply<Radix, MinDigits, MaxDigits, Accumulate> extractor;
return extractor::f(scan, n, count);
}
};
///////////////////////////////////////////////////////////////////////
//
// uint_parser_impl class
//
///////////////////////////////////////////////////////////////////////
template <
typename T = unsigned,
int Radix = 10,
unsigned MinDigits = 1,
int MaxDigits = -1
>
struct uint_parser_impl
: parser<uint_parser_impl<T, Radix, MinDigits, MaxDigits> >
{
typedef uint_parser_impl<T, Radix, MinDigits, MaxDigits> self_t;
template <typename ScannerT>
struct result
{
typedef typename match_result<ScannerT, T>::type type;
};
template <typename ScannerT>
typename parser_result<self_t, ScannerT>::type
parse(ScannerT const& scan) const
{
if (!scan.at_end())
{
T n = 0;
std::size_t count = 0;
typename ScannerT::iterator_t save = scan.first;
if (extract_int<Radix, MinDigits, MaxDigits>::
f(scan, n, count))
{
return scan.create_match(count, n, save, scan.first);
}
// return no-match if number overflows
}
return scan.no_match();
}
};
///////////////////////////////////////////////////////////////////////
//
// int_parser_impl class
//
///////////////////////////////////////////////////////////////////////
template <
typename T = unsigned,
int Radix = 10,
unsigned MinDigits = 1,
int MaxDigits = -1
>
struct int_parser_impl
: parser<int_parser_impl<T, Radix, MinDigits, MaxDigits> >
{
typedef int_parser_impl<T, Radix, MinDigits, MaxDigits> self_t;
template <typename ScannerT>
struct result
{
typedef typename match_result<ScannerT, T>::type type;
};
template <typename ScannerT>
typename parser_result<self_t, ScannerT>::type
parse(ScannerT const& scan) const
{
typedef extract_int<Radix, MinDigits, MaxDigits,
negative_accumulate<Radix> > extract_int_neg_t;
typedef extract_int<Radix, MinDigits, MaxDigits>
extract_int_pos_t;
if (!scan.at_end())
{
T n = 0;
std::size_t count = 0;
typename ScannerT::iterator_t save = scan.first;
bool hit = impl::extract_sign(scan, count);
if (hit)
hit = extract_int_neg_t::f(scan, n, count);
else
hit = extract_int_pos_t::f(scan, n, count);
if (hit)
return scan.create_match(count, n, save, scan.first);
else
scan.first = save;
// return no-match if number overflows or underflows
}
return scan.no_match();
}
};
///////////////////////////////////////////////////////////////////////
//
// real_parser_impl class
//
///////////////////////////////////////////////////////////////////////
#if (defined(BOOST_MSVC) && (BOOST_MSVC <= 1310))
#pragma warning(push)
#pragma warning(disable:4127)
#endif
template <typename RT, typename T, typename RealPoliciesT>
struct real_parser_impl
{
typedef real_parser_impl<RT, T, RealPoliciesT> self_t;
template <typename ScannerT>
RT parse_main(ScannerT const& scan) const
{
if (scan.at_end())
return scan.no_match();
typename ScannerT::iterator_t save = scan.first;
typedef typename parser_result<sign_parser, ScannerT>::type
sign_match_t;
typedef typename parser_result<chlit<>, ScannerT>::type
exp_match_t;
sign_match_t sign_match = RealPoliciesT::parse_sign(scan);
std::size_t count = sign_match ? sign_match.length() : 0;
bool neg = sign_match.has_valid_attribute() ?
sign_match.value() : false;
RT n_match = RealPoliciesT::parse_n(scan);
T n = n_match.has_valid_attribute() ?
n_match.value() : T(0);
bool got_a_number = n_match;
exp_match_t e_hit;
if (!got_a_number && !RealPoliciesT::allow_leading_dot)
return scan.no_match();
else
count += n_match.length();
if (neg)
n = -n;
if (RealPoliciesT::parse_dot(scan))
{
// We got the decimal point. Now we will try to parse
// the fraction if it is there. If not, it defaults
// to zero (0) only if we already got a number.
if (RT hit = RealPoliciesT::parse_frac_n(scan))
{
hit.value(hit.value()
* BOOST_SPIRIT_IMPL_STD_NS::
pow(T(10), T(-hit.length())));
if (neg)
n -= hit.value();
else
n += hit.value();
count += hit.length() + 1;
}
else if (!got_a_number ||
!RealPoliciesT::allow_trailing_dot)
return scan.no_match();
e_hit = RealPoliciesT::parse_exp(scan);
}
else
{
// We have reached a point where we
// still haven't seen a number at all.
// We return early with a no-match.
if (!got_a_number)
return scan.no_match();
// If we must expect a dot and we didn't see
// an exponent, return early with a no-match.
e_hit = RealPoliciesT::parse_exp(scan);
if (RealPoliciesT::expect_dot && !e_hit)
return scan.no_match();
}
if (e_hit)
{
// We got the exponent prefix. Now we will try to parse the
// actual exponent. It is an error if it is not there.
if (RT e_n_hit = RealPoliciesT::parse_exp_n(scan))
{
n *= BOOST_SPIRIT_IMPL_STD_NS::
pow(T(10), T(e_n_hit.value()));
count += e_n_hit.length() + e_hit.length();
}
else
{
// Oops, no exponent, return a no-match
return scan.no_match();
}
}
return scan.create_match(count, n, save, scan.first);
}
template <typename ScannerT>
static RT parse(ScannerT const& scan)
{
static self_t this_;
return impl::implicit_lexeme_parse<RT>(this_, scan, scan);
}
};
#if (defined(BOOST_MSVC) && (BOOST_MSVC <= 1310))
#pragma warning(pop)
#endif
} // namespace impl
///////////////////////////////////////////////////////////////////////////////
}} // namespace boost::spirit
#endif
#undef BOOST_SPIRIT_IMPL_STD_NS
