479 lines
17 KiB
Plaintext
479 lines
17 KiB
Plaintext
/*=============================================================================
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Copyright (c) 1998-2003 Joel de Guzman
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Copyright (c) 2001-2003 Hartmut Kaiser
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http://spirit.sourceforge.net/
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Use, modification and distribution is subject to the Boost Software
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License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
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http://www.boost.org/LICENSE_1_0.txt)
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=============================================================================*/
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#ifndef BOOST_SPIRIT_NUMERICS_IPP
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#define BOOST_SPIRIT_NUMERICS_IPP
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#include <boost/config/no_tr1/cmath.hpp>
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#include <limits>
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namespace boost { namespace spirit {
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BOOST_SPIRIT_CLASSIC_NAMESPACE_BEGIN
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struct sign_parser; // forward declaration only
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namespace impl
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{
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///////////////////////////////////////////////////////////////////////
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//
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// Extract the prefix sign (- or +)
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//
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///////////////////////////////////////////////////////////////////////
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template <typename ScannerT>
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bool
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extract_sign(ScannerT const& scan, std::size_t& count)
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{
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// Extract the sign
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count = 0;
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bool neg = *scan == '-';
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if (neg || (*scan == '+'))
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{
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++scan;
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++count;
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return neg;
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}
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return false;
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}
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///////////////////////////////////////////////////////////////////////
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//
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// Traits class for radix specific number conversion
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//
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// Convert a digit from character representation, ch, to binary
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// representation, returned in val.
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// Returns whether the conversion was successful.
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//
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// template<typename CharT> static bool digit(CharT ch, T& val);
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//
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///////////////////////////////////////////////////////////////////////
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template<const int Radix>
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struct radix_traits;
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////////////////////////////////// Binary
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template<>
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struct radix_traits<2>
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{
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template<typename CharT, typename T>
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static bool digit(CharT ch, T& val)
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{
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val = ch - '0';
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return ('0' == ch || '1' == ch);
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}
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};
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////////////////////////////////// Octal
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template<>
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struct radix_traits<8>
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{
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template<typename CharT, typename T>
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static bool digit(CharT ch, T& val)
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{
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val = ch - '0';
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return ('0' <= ch && ch <= '7');
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}
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};
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////////////////////////////////// Decimal
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template<>
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struct radix_traits<10>
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{
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template<typename CharT, typename T>
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static bool digit(CharT ch, T& val)
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{
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val = ch - '0';
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return impl::isdigit_(ch);
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}
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};
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////////////////////////////////// Hexadecimal
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template<>
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struct radix_traits<16>
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{
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template<typename CharT, typename T>
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static bool digit(CharT ch, T& val)
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{
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if (radix_traits<10>::digit(ch, val))
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return true;
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CharT lc = impl::tolower_(ch);
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if ('a' <= lc && lc <= 'f')
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{
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val = lc - 'a' + 10;
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return true;
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}
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return false;
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}
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};
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///////////////////////////////////////////////////////////////////////
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//
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// Helper templates for encapsulation of radix specific
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// conversion of an input string to an integral value.
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//
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// main entry point:
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//
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// extract_int<Radix, MinDigits, MaxDigits, Accumulate>
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// ::f(first, last, n, count);
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//
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// The template parameter Radix represents the radix of the
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// number contained in the parsed string. The template
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// parameter MinDigits specifies the minimum digits to
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// accept. The template parameter MaxDigits specifies the
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// maximum digits to parse. A -1 value for MaxDigits will
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// make it parse an arbitrarilly large number as long as the
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// numeric type can hold it. Accumulate is either
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// positive_accumulate<Radix> (default) for parsing positive
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// numbers or negative_accumulate<Radix> otherwise.
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// Checking is only performed when std::numeric_limits<T>::
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// is_specialized is true. Otherwise, there's no way to
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// do the check.
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//
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// scan.first and scan.last are iterators as usual (i.e.
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// first is mutable and is moved forward when a match is
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// found), n is a variable that holds the number (passed by
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// reference). The number of parsed characters is added to
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// count (also passed by reference)
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//
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// NOTE:
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// Returns a non-match, if the number to parse
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// overflows (or underflows) the used type.
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//
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// BEWARE:
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// the parameters 'n' and 'count' should be properly
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// initialized before calling this function.
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//
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///////////////////////////////////////////////////////////////////////
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#if defined(BOOST_MSVC)
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#pragma warning(push)
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#pragma warning(disable:4127) //conditional expression is constant
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#endif
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template <typename T, int Radix>
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struct positive_accumulate
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{
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// Use this accumulator if number is positive
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static bool add(T& n, T digit)
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{
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if (std::numeric_limits<T>::is_specialized)
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{
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static T const max = (std::numeric_limits<T>::max)();
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static T const max_div_radix = max/Radix;
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if (n > max_div_radix)
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return false;
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n *= Radix;
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if (n > max - digit)
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return false;
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n += digit;
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return true;
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}
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else
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{
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n *= Radix;
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n += digit;
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return true;
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}
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}
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};
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template <typename T, int Radix>
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struct negative_accumulate
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{
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// Use this accumulator if number is negative
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static bool add(T& n, T digit)
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{
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if (std::numeric_limits<T>::is_specialized)
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{
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typedef std::numeric_limits<T> num_limits;
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static T const min =
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(!num_limits::is_integer && num_limits::is_signed && num_limits::has_denorm) ?
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-(num_limits::max)() : (num_limits::min)();
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static T const min_div_radix = min/Radix;
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if (n < min_div_radix)
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return false;
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n *= Radix;
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if (n < min + digit)
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return false;
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n -= digit;
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return true;
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}
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else
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{
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n *= Radix;
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n -= digit;
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return true;
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}
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}
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};
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template <int MaxDigits>
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inline bool allow_more_digits(std::size_t i)
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{
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return i < MaxDigits;
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}
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template <>
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inline bool allow_more_digits<-1>(std::size_t)
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{
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return true;
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}
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//////////////////////////////////
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template <
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int Radix, unsigned MinDigits, int MaxDigits,
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typename Accumulate
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>
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struct extract_int
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{
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template <typename ScannerT, typename T>
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static bool
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f(ScannerT& scan, T& n, std::size_t& count)
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{
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std::size_t i = 0;
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T digit;
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while( allow_more_digits<MaxDigits>(i) && !scan.at_end() &&
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radix_traits<Radix>::digit(*scan, digit) )
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{
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if (!Accumulate::add(n, digit))
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return false; // Overflow
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++i, ++scan, ++count;
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}
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return i >= MinDigits;
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}
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};
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///////////////////////////////////////////////////////////////////////
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//
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// uint_parser_impl class
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//
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///////////////////////////////////////////////////////////////////////
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template <
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typename T = unsigned,
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int Radix = 10,
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unsigned MinDigits = 1,
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int MaxDigits = -1
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>
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struct uint_parser_impl
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: parser<uint_parser_impl<T, Radix, MinDigits, MaxDigits> >
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{
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typedef uint_parser_impl<T, Radix, MinDigits, MaxDigits> self_t;
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template <typename ScannerT>
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struct result
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{
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typedef typename match_result<ScannerT, T>::type type;
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};
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template <typename ScannerT>
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typename parser_result<self_t, ScannerT>::type
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parse(ScannerT const& scan) const
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{
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if (!scan.at_end())
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{
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T n = 0;
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std::size_t count = 0;
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typename ScannerT::iterator_t save = scan.first;
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if (extract_int<Radix, MinDigits, MaxDigits,
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positive_accumulate<T, Radix> >::f(scan, n, count))
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{
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return scan.create_match(count, n, save, scan.first);
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}
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// return no-match if number overflows
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}
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return scan.no_match();
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}
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};
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///////////////////////////////////////////////////////////////////////
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//
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// int_parser_impl class
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//
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///////////////////////////////////////////////////////////////////////
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template <
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typename T = unsigned,
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int Radix = 10,
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unsigned MinDigits = 1,
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int MaxDigits = -1
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>
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struct int_parser_impl
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: parser<int_parser_impl<T, Radix, MinDigits, MaxDigits> >
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{
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typedef int_parser_impl<T, Radix, MinDigits, MaxDigits> self_t;
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template <typename ScannerT>
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struct result
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{
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typedef typename match_result<ScannerT, T>::type type;
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};
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template <typename ScannerT>
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typename parser_result<self_t, ScannerT>::type
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parse(ScannerT const& scan) const
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{
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typedef extract_int<Radix, MinDigits, MaxDigits,
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negative_accumulate<T, Radix> > extract_int_neg_t;
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typedef extract_int<Radix, MinDigits, MaxDigits,
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positive_accumulate<T, Radix> > extract_int_pos_t;
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if (!scan.at_end())
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{
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T n = 0;
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std::size_t count = 0;
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typename ScannerT::iterator_t save = scan.first;
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bool hit = impl::extract_sign(scan, count);
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if (hit)
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hit = extract_int_neg_t::f(scan, n, count);
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else
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hit = extract_int_pos_t::f(scan, n, count);
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if (hit)
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return scan.create_match(count, n, save, scan.first);
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else
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scan.first = save;
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// return no-match if number overflows or underflows
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}
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return scan.no_match();
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}
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};
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///////////////////////////////////////////////////////////////////////
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//
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// real_parser_impl class
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//
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///////////////////////////////////////////////////////////////////////
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template <typename RT, typename T, typename RealPoliciesT>
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struct real_parser_impl
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{
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typedef real_parser_impl<RT, T, RealPoliciesT> self_t;
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template <typename ScannerT>
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RT parse_main(ScannerT const& scan) const
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{
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if (scan.at_end())
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return scan.no_match();
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typename ScannerT::iterator_t save = scan.first;
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typedef typename parser_result<sign_parser, ScannerT>::type
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sign_match_t;
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typedef typename parser_result<chlit<>, ScannerT>::type
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exp_match_t;
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sign_match_t sign_match = RealPoliciesT::parse_sign(scan);
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std::size_t count = sign_match ? sign_match.length() : 0;
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bool neg = sign_match.has_valid_attribute() ?
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sign_match.value() : false;
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RT n_match = RealPoliciesT::parse_n(scan);
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T n = n_match.has_valid_attribute() ?
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n_match.value() : T(0);
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bool got_a_number = n_match;
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exp_match_t e_hit;
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if (!got_a_number && !RealPoliciesT::allow_leading_dot)
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return scan.no_match();
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else
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count += n_match.length();
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if (neg)
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n = -n;
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if (RealPoliciesT::parse_dot(scan))
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{
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// We got the decimal point. Now we will try to parse
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// the fraction if it is there. If not, it defaults
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// to zero (0) only if we already got a number.
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if (RT hit = RealPoliciesT::parse_frac_n(scan))
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{
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#if !defined(BOOST_NO_STDC_NAMESPACE)
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using namespace std; // allow for ADL to find pow()
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#endif
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hit.value(hit.value()
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* pow(T(10), T(-hit.length())));
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if (neg)
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n -= hit.value();
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else
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n += hit.value();
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count += hit.length() + 1;
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}
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else if (!got_a_number ||
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!RealPoliciesT::allow_trailing_dot)
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return scan.no_match();
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e_hit = RealPoliciesT::parse_exp(scan);
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}
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else
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{
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// We have reached a point where we
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// still haven't seen a number at all.
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// We return early with a no-match.
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if (!got_a_number)
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return scan.no_match();
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// If we must expect a dot and we didn't see
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// an exponent, return early with a no-match.
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e_hit = RealPoliciesT::parse_exp(scan);
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if (RealPoliciesT::expect_dot && !e_hit)
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return scan.no_match();
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}
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if (e_hit)
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{
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// We got the exponent prefix. Now we will try to parse the
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// actual exponent. It is an error if it is not there.
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if (RT e_n_hit = RealPoliciesT::parse_exp_n(scan))
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{
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#if !defined(BOOST_NO_STDC_NAMESPACE)
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using namespace std; // allow for ADL to find pow()
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#endif
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n *= pow(T(10), T(e_n_hit.value()));
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count += e_n_hit.length() + e_hit.length();
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}
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else
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{
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// Oops, no exponent, return a no-match
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return scan.no_match();
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}
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}
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return scan.create_match(count, n, save, scan.first);
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}
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template <typename ScannerT>
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static RT parse(ScannerT const& scan)
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{
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static self_t this_;
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return impl::implicit_lexeme_parse<RT>(this_, scan, scan);
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}
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};
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#if defined(BOOST_MSVC)
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#pragma warning(pop)
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#endif
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} // namespace impl
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///////////////////////////////////////////////////////////////////////////////
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BOOST_SPIRIT_CLASSIC_NAMESPACE_END
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}} // namespace boost::spirit
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#endif
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