boost/format/parsing.hpp
// ----------------------------------------------------------------------------
// parsing.hpp : implementation of the parsing member functions
// ( parse, parse_printf_directive)
// ----------------------------------------------------------------------------
// Copyright Samuel Krempp 2003. Use, modification, and distribution are
// 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)
// see http://www.boost.org/libs/format for library home page
// ----------------------------------------------------------------------------
#ifndef BOOST_FORMAT_PARSING_HPP
#define BOOST_FORMAT_PARSING_HPP
#include <boost/format/format_class.hpp>
#include <boost/format/exceptions.hpp>
#include <boost/throw_exception.hpp>
#include <boost/assert.hpp>
namespace boost {
namespace io {
namespace detail {
#if defined(BOOST_NO_STD_LOCALE)
// streams will be used for narrow / widen. but these methods are not const
template<class T>
T& const_or_not(const T& x) {
return const_cast<T&> (x);
}
#else
template<class T>
const T& const_or_not(const T& x) {
return x;
}
#endif
template<class Ch, class Facet> inline
char wrap_narrow(const Facet& fac, Ch c, char deflt) {
return const_or_not(fac).narrow(c, deflt);
}
template<class Ch, class Facet> inline
bool wrap_isdigit(const Facet& fac, Ch c) {
#if ! defined( BOOST_NO_LOCALE_ISDIGIT )
return fac.is(std::ctype<Ch>::digit, c);
# else
using namespace std;
return isdigit(c);
#endif
}
template<class Iter, class Facet>
Iter wrap_scan_notdigit(const Facet & fac, Iter beg, Iter end) {
using namespace std;
for( ; beg!=end && wrap_isdigit(fac, *beg); ++beg) ;
return beg;
}
// Input : [start, last) iterators range and a
// a Facet to use its widen/narrow member function
// Effects : read sequence and convert digits into integral n, of type Res
// Returns : n
template<class Res, class Iter, class Facet>
Iter str2int (const Iter & start, const Iter & last, Res & res,
const Facet& fac)
{
using namespace std;
Iter it;
res=0;
for(it=start; it != last && wrap_isdigit(fac, *it); ++it ) {
char cur_ch = wrap_narrow(fac, *it, 0); // cant fail.
res *= 10;
res += cur_ch - '0'; // 22.2.1.1.2.13 of the C++ standard
}
return it;
}
// skip printf's "asterisk-fields" directives in the format-string buf
// Input : char string, with starting index *pos_p
// a Facet merely to use its widen/narrow member function
// Effects : advance *pos_p by skipping printf's asterisk fields.
// Returns : nothing
template<class Iter, class Facet>
Iter skip_asterisk(Iter start, Iter last, const Facet& fac)
{
using namespace std;
++ start;
start = wrap_scan_notdigit(fac, start, last);
if(start!=last && *start== const_or_not(fac).widen( '$') )
++start;
return start;
}
// auxiliary func called by parse_printf_directive
// for centralising error handling
// it either throws if user sets the corresponding flag, or does nothing.
inline void maybe_throw_exception(unsigned char exceptions,
std::size_t pos, std::size_t size)
{
if(exceptions & io::bad_format_string_bit)
boost::throw_exception(io::bad_format_string(pos, size) );
}
// Input: the position of a printf-directive in the format-string
// a basic_ios& merely to use its widen/narrow member function
// a bitset'exceptions' telling whether to throw exceptions on errors.
// Returns:
// true if parse succeeded (ignore some errors if exceptions disabled)
// false if it failed so bad that the directive should be printed verbatim
// Effects:
// start is incremented so that *start is the first char after
// this directive
// *fpar is set with the parameters read in the directive
template<class Ch, class Tr, class Alloc, class Iter, class Facet>
bool parse_printf_directive(Iter & start, const Iter& last,
detail::format_item<Ch, Tr, Alloc> * fpar,
const Facet& fac,
std::size_t offset, unsigned char exceptions)
{
typedef typename basic_format<Ch, Tr, Alloc>::format_item_t format_item_t;
fpar->argN_ = format_item_t::argN_no_posit; // if no positional-directive
bool precision_set = false;
bool in_brackets=false;
Iter start0 = start;
std::size_t fstring_size = last-start0+offset;
if(start>= last) { // empty directive : this is a trailing %
maybe_throw_exception(exceptions, start-start0 + offset, fstring_size);
return false;
}
if(*start== const_or_not(fac).widen( '|')) {
in_brackets=true;
if( ++start >= last ) {
maybe_throw_exception(exceptions, start-start0 + offset, fstring_size);
return false;
}
}
// the flag '0' would be picked as a digit for argument order, but here it's a flag :
if(*start== const_or_not(fac).widen( '0'))
goto parse_flags;
// handle argument order (%2$d) or possibly width specification: %2d
if(wrap_isdigit(fac, *start)) {
int n;
start = str2int(start, last, n, fac);
if( start >= last ) {
maybe_throw_exception(exceptions, start-start0+offset, fstring_size);
return false;
}
// %N% case : this is already the end of the directive
if( *start == const_or_not(fac).widen( '%') ) {
fpar->argN_ = n-1;
++start;
if( in_brackets)
maybe_throw_exception(exceptions, start-start0+offset, fstring_size);
// but don't return. maybe "%" was used in lieu of '$', so we go on.
else
return true;
}
if ( *start== const_or_not(fac).widen( '$') ) {
fpar->argN_ = n-1;
++start;
}
else {
// non-positionnal directive
fpar->fmtstate_.width_ = n;
fpar->argN_ = format_item_t::argN_no_posit;
goto parse_precision;
}
}
parse_flags:
// handle flags
while ( start != last) { // as long as char is one of + - = _ # 0 l h or ' '
// misc switches
switch ( wrap_narrow(fac, *start, 0)) {
case '\'' : break; // no effect yet. (painful to implement)
case 'l':
case 'h': // short/long modifier : for printf-comaptibility (no action needed)
break;
case '-':
fpar->fmtstate_.flags_ |= std::ios_base::left;
break;
case '=':
fpar->pad_scheme_ |= format_item_t::centered;
break;
case '_':
fpar->fmtstate_.flags_ |= std::ios_base::internal;
break;
case ' ':
fpar->pad_scheme_ |= format_item_t::spacepad;
break;
case '+':
fpar->fmtstate_.flags_ |= std::ios_base::showpos;
break;
case '0':
fpar->pad_scheme_ |= format_item_t::zeropad;
// need to know alignment before really setting flags,
// so just add 'zeropad' flag for now, it will be processed later.
break;
case '#':
fpar->fmtstate_.flags_ |= std::ios_base::showpoint | std::ios_base::showbase;
break;
default:
goto parse_width;
}
++start;
} // loop on flag.
if( start>=last) {
maybe_throw_exception(exceptions, start-start0+offset, fstring_size);
return true;
}
parse_width:
// handle width spec
// first skip 'asterisk fields' : *, or *N$
if(*start == const_or_not(fac).widen( '*') )
start = skip_asterisk(start, last, fac);
if(start!=last && wrap_isdigit(fac, *start))
start = str2int(start, last, fpar->fmtstate_.width_, fac);
parse_precision:
if( start>= last) {
maybe_throw_exception(exceptions, start-start0+offset, fstring_size);
return true;
}
// handle precision spec
if (*start== const_or_not(fac).widen( '.')) {
++start;
if(start != last && *start == const_or_not(fac).widen( '*') )
start = skip_asterisk(start, last, fac);
if(start != last && wrap_isdigit(fac, *start)) {
start = str2int(start, last, fpar->fmtstate_.precision_, fac);
precision_set = true;
}
else
fpar->fmtstate_.precision_ =0;
}
// handle formatting-type flags :
while( start != last && ( *start== const_or_not(fac).widen( 'l')
|| *start== const_or_not(fac).widen( 'L')
|| *start== const_or_not(fac).widen( 'h')) )
++start;
if( start>=last) {
maybe_throw_exception(exceptions, start-start0+offset, fstring_size);
return true;
}
if( in_brackets && *start== const_or_not(fac).widen( '|') ) {
++start;
return true;
}
switch ( wrap_narrow(fac, *start, 0) ) {
case 'X':
fpar->fmtstate_.flags_ |= std::ios_base::uppercase;
case 'p': // pointer => set hex.
case 'x':
fpar->fmtstate_.flags_ &= ~std::ios_base::basefield;
fpar->fmtstate_.flags_ |= std::ios_base::hex;
break;
case 'o':
fpar->fmtstate_.flags_ &= ~std::ios_base::basefield;
fpar->fmtstate_.flags_ |= std::ios_base::oct;
break;
case 'E':
fpar->fmtstate_.flags_ |= std::ios_base::uppercase;
case 'e':
fpar->fmtstate_.flags_ &= ~std::ios_base::floatfield;
fpar->fmtstate_.flags_ |= std::ios_base::scientific;
fpar->fmtstate_.flags_ &= ~std::ios_base::basefield;
fpar->fmtstate_.flags_ |= std::ios_base::dec;
break;
case 'f':
fpar->fmtstate_.flags_ &= ~std::ios_base::floatfield;
fpar->fmtstate_.flags_ |= std::ios_base::fixed;
case 'u':
case 'd':
case 'i':
fpar->fmtstate_.flags_ &= ~std::ios_base::basefield;
fpar->fmtstate_.flags_ |= std::ios_base::dec;
break;
case 'T':
++start;
if( start >= last)
maybe_throw_exception(exceptions, start-start0+offset, fstring_size);
else
fpar->fmtstate_.fill_ = *start;
fpar->pad_scheme_ |= format_item_t::tabulation;
fpar->argN_ = format_item_t::argN_tabulation;
break;
case 't':
fpar->fmtstate_.fill_ = const_or_not(fac).widen( ' ');
fpar->pad_scheme_ |= format_item_t::tabulation;
fpar->argN_ = format_item_t::argN_tabulation;
break;
case 'G':
fpar->fmtstate_.flags_ |= std::ios_base::uppercase;
break;
case 'g': // 'g' conversion is default for floats.
fpar->fmtstate_.flags_ &= ~std::ios_base::basefield;
fpar->fmtstate_.flags_ |= std::ios_base::dec;
// CLEAR all floatield flags, so stream will CHOOSE
fpar->fmtstate_.flags_ &= ~std::ios_base::floatfield;
break;
case 'C':
case 'c':
fpar->truncate_ = 1;
break;
case 'S':
case 's':
if(precision_set) // handle truncation manually, with own parameter.
fpar->truncate_ = fpar->fmtstate_.precision_;
fpar->fmtstate_.precision_ = 6; // default stream precision.
break;
case 'n' :
fpar->argN_ = format_item_t::argN_ignored;
break;
default:
maybe_throw_exception(exceptions, start-start0+offset, fstring_size);
}
++start;
if( in_brackets ) {
if( start != last && *start== const_or_not(fac).widen( '|') ) {
++start;
return true;
}
else maybe_throw_exception(exceptions, start-start0+offset, fstring_size);
}
return true;
}
// -end parse_printf_directive()
template<class String, class Facet>
int upper_bound_from_fstring(const String& buf,
const typename String::value_type arg_mark,
const Facet& fac,
unsigned char exceptions)
{
// quick-parsing of the format-string to count arguments mark (arg_mark, '%')
// returns : upper bound on the number of format items in the format strings
using namespace boost::io;
typename String::size_type i1=0;
int num_items=0;
while( (i1=buf.find(arg_mark,i1)) != String::npos ) {
if( i1+1 >= buf.size() ) {
if(exceptions & bad_format_string_bit)
boost::throw_exception(bad_format_string(i1, buf.size() )); // must not end in ".. %"
else {
++num_items;
break;
}
}
if(buf[i1+1] == buf[i1] ) {// escaped "%%"
i1+=2; continue;
}
++i1;
// in case of %N% directives, dont count it double (wastes allocations..) :
i1 = detail::wrap_scan_notdigit(fac, buf.begin()+i1, buf.end()) - buf.begin();
if( i1 < buf.size() && buf[i1] == arg_mark )
++i1;
++num_items;
}
return num_items;
}
template<class String> inline
void append_string(String& dst, const String& src,
const typename String::size_type beg,
const typename String::size_type end) {
#if !defined(BOOST_NO_STRING_APPEND)
dst.append(src.begin()+beg, src.begin()+end);
#else
dst += src.substr(beg, end-beg);
#endif
}
} // detail namespace
} // io namespace
// -----------------------------------------------
// format :: parse(..)
template<class Ch, class Tr, class Alloc>
basic_format<Ch, Tr, Alloc>& basic_format<Ch, Tr, Alloc>::
parse (const string_type& buf) {
// parse the format-string
using namespace std;
#if !defined(BOOST_NO_STD_LOCALE)
const std::ctype<Ch> & fac = BOOST_USE_FACET( std::ctype<Ch>, getloc());
#else
io::basic_oaltstringstream<Ch, Tr, Alloc> fac;
//has widen and narrow even on compilers without locale
#endif
const Ch arg_mark = io::detail::const_or_not(fac).widen( '%');
bool ordered_args=true;
int max_argN=-1;
// A: find upper_bound on num_items and allocates arrays
int num_items = io::detail::upper_bound_from_fstring(buf, arg_mark, fac, exceptions());
make_or_reuse_data(num_items);
// B: Now the real parsing of the format string :
num_items=0;
typename string_type::size_type i0=0, i1=0;
typename string_type::const_iterator it;
bool special_things=false;
int cur_item=0;
while( (i1=buf.find(arg_mark,i1)) != string_type::npos ) {
string_type & piece = (cur_item==0) ? prefix_ : items_[cur_item-1].appendix_;
if( buf[i1+1] == buf[i1] ) { // escaped mark, '%%'
io::detail::append_string(piece, buf, i0, i1+1);
i1+=2; i0=i1;
continue;
}
BOOST_ASSERT( static_cast<unsigned int>(cur_item) < items_.size() || cur_item==0);
if(i1!=i0) {
io::detail::append_string(piece, buf, i0, i1);
i0=i1;
}
++i1;
it = buf.begin()+i1;
bool parse_ok = io::detail::parse_printf_directive(
it, buf.end(), &items_[cur_item], fac, i1, exceptions());
i1 = it - buf.begin();
if( ! parse_ok ) // the directive will be printed verbatim
continue;
i0=i1;
items_[cur_item].compute_states(); // process complex options, like zeropad, into params
int argN=items_[cur_item].argN_;
if(argN == format_item_t::argN_ignored)
continue;
if(argN ==format_item_t::argN_no_posit)
ordered_args=false;
else if(argN == format_item_t::argN_tabulation) special_things=true;
else if(argN > max_argN) max_argN = argN;
++num_items;
++cur_item;
} // loop on %'s
BOOST_ASSERT(cur_item == num_items);
// store the final piece of string
{
string_type & piece = (cur_item==0) ? prefix_ : items_[cur_item-1].appendix_;
io::detail::append_string(piece, buf, i0, buf.size());
}
if( !ordered_args) {
if(max_argN >= 0 ) { // dont mix positional with non-positionnal directives
if(exceptions() & io::bad_format_string_bit)
boost::throw_exception(io::bad_format_string(max_argN, 0));
// else do nothing. => positionnal arguments are processed as non-positionnal
}
// set things like it would have been with positional directives :
int non_ordered_items = 0;
for(int i=0; i< num_items; ++i)
if(items_[i].argN_ == format_item_t::argN_no_posit) {
items_[i].argN_ = non_ordered_items;
++non_ordered_items;
}
max_argN = non_ordered_items-1;
}
// C: set some member data :
items_.resize(num_items, format_item_t(io::detail::const_or_not(fac).widen( ' ')) );
if(special_things) style_ |= special_needs;
num_args_ = max_argN + 1;
if(ordered_args) style_ |= ordered;
else style_ &= ~ordered;
return *this;
}
} // namespace boost
#endif // BOOST_FORMAT_PARSING_HPP