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+// -*- C++ -*-
+//  Boost general library 'format'   ---------------------------
+//  See http://www.boost.org for updates, documentation, and revision history.
+
+//  (C) Samuel Krempp 2001
+//                  krempp@crans.ens-cachan.fr
+//  Permission to copy, use, modify, sell and
+//  distribute this software is granted provided this copyright notice appears
+//  in all copies. This software is provided "as is" without express or implied
+//  warranty, and with no claim as to its suitability for any purpose.
+
+// ideas taken from Rudiger Loos's format class
+// and Karl Nelson's ofstream (also took its parsing code as basis for printf parsing)
+
+// ------------------------------------------------------------------------------
+// parsing.hpp :  implementation of the parsing member functions
+//                      ( parse, parse_printf_directive)
+// ------------------------------------------------------------------------------
+
+
+#ifndef BOOST_FORMAT_PARSING_HPP
+#define BOOST_FORMAT_PARSING_HPP
+
+
+#include <boost/format.hpp>
+#include <boost/throw_exception.hpp>
+#include <boost/assert.hpp>
+
+
+namespace boost {
+namespace io {
+namespace detail {
+
+  template<class Stream> inline
+  bool wrap_isdigit(char c, Stream &os) 
+  {
+#ifndef BOOST_NO_LOCALE_ISIDIGIT
+    return std::isdigit(c, os.rdbuf()->getloc() );
+# else
+    using namespace std;
+    return isdigit(c); 
+#endif 
+  } //end- wrap_isdigit(..)
+
+  template<class Res> inline
+  Res str2int(const std::string& s, 
+              std::string::size_type start, 
+              BOOST_IO_STD ios &os,
+              const Res = Res(0)  ) 
+    // Input : char string, with starting index
+    //         a basic_ios& merely to call its widen/narrow member function in the desired locale.
+    // Effects : reads s[start:] and converts digits into an integral n, of type Res
+    // Returns : n
+  {
+    Res n = 0;
+    while(start<s.size() && wrap_isdigit(s[start], os) ) {
+      char cur_ch = s[start];
+      BOOST_ASSERT(cur_ch != 0 ); // since we called isdigit, this should not happen.
+      n *= 10;
+      n += cur_ch - '0'; // 22.2.1.1.2 of the C++ standard
+      ++start;
+    }
+    return n;
+  }
+
+  void skip_asterisk(const std::string & buf, 
+                     std::string::size_type * pos_p,
+                     BOOST_IO_STD ios &os)
+    // skip printf's "asterisk-fields" directives in the format-string buf
+    // Input : char string, with starting index *pos_p
+    //         a basic_ios& merely to call its widen/narrow member function in the desired locale.
+    // Effects : advance *pos_p by skipping printf's asterisk fields.
+    // Returns : nothing
+  {
+    using namespace std;
+    BOOST_ASSERT( pos_p != 0);
+    if(*pos_p >= buf.size() ) return;
+    if(buf[ *pos_p]=='*') {
+      ++ (*pos_p);
+      while (*pos_p < buf.size() && wrap_isdigit(buf[*pos_p],os)) ++(*pos_p);
+      if(buf[*pos_p]=='$') ++(*pos_p);
+    }
+  }
+
+
+  inline void maybe_throw_exception( unsigned char exceptions)
+    // auxiliary func called by parse_printf_directive
+    // for centralising error handling
+    // it either throws if user sets the corresponding flag, or does nothing.
+  {
+    if(exceptions & io::bad_format_string_bit)
+          boost::throw_exception(io::bad_format_string());
+  }
+    
+
+
+  bool parse_printf_directive(const std::string & buf,
+                              std::string::size_type * pos_p,
+                              detail::format_item * fpar,
+                              BOOST_IO_STD ios &os,
+                              unsigned char exceptions)
+    // Input   : a 'printf-directive' in the format-string, starting at buf[ *pos_p ]
+    //           a basic_ios& merely to call its widen/narrow member function in the desired locale.
+    //           a bitset'excpetions' telling whether to throw exceptions on errors.
+    // Returns : true if parse somehow succeeded (possibly ignoring errors if exceptions disabled) 
+    //           false if it failed so bad that the directive should be printed verbatim
+    // Effects : - *pos_p is incremented so that buf[*pos_p] is the first char after the directive
+    //           - *fpar is set with the parameters read in the directive
+  {
+    typedef format_item  format_item_t;
+    BOOST_ASSERT( pos_p != 0);
+    std::string::size_type       &i1 = *pos_p,      
+                                                        i0; 
+    fpar->argN_ = format_item_t::argN_no_posit;  // if no positional-directive
+
+    bool in_brackets=false;
+    if(buf[i1]=='|')
+      {
+        in_brackets=true;
+        if( ++i1 >= buf.size() ) {
+          maybe_throw_exception(exceptions);
+          return false;
+        }
+      }
+
+    // the flag '0' would be picked as a digit for argument order, but here it's a flag :
+    if(buf[i1]=='0') 
+      goto parse_flags;
+
+    // handle argument order (%2$d)  or possibly width specification: %2d
+    i0 = i1;  // save position before digits
+    while (i1 < buf.size() && wrap_isdigit(buf[i1], os))
+      ++i1;
+    if (i1!=i0) 
+      {
+        if( i1 >= buf.size() ) {
+          maybe_throw_exception(exceptions);
+          return false;
+        }
+        int n=str2int(buf,i0, os, int(0) );
+        
+        // %N% case : this is already the end of the directive
+        if( buf[i1] == '%' ) 
+          {
+            fpar->argN_ = n-1;
+            ++i1;
+            if( in_brackets) 
+              maybe_throw_exception(exceptions); 
+              // but don't return.  maybe "%" was used in lieu of '$', so we go on.
+            else return true;
+          }
+
+        if ( buf[i1]=='$' ) 
+          {
+            fpar->argN_ = n-1;
+            ++i1;
+          } 
+        else  
+          {
+            // non-positionnal directive
+            fpar->ref_state_.width_ = n;
+            fpar->argN_  = format_item_t::argN_no_posit;
+            goto parse_precision;
+          }
+      }
+    
+  parse_flags: 
+    // handle flags
+    while ( i1 <buf.size()) // as long as char is one of + - = # 0 l h   or ' '
+      {  
+        // misc switches
+        switch (buf[i1]) 
+          {
+          case '\'' : break; // no effect yet. (painful to implement)
+          case 'l':
+          case 'h':  // short/long modifier : for printf-comaptibility (no action needed)
+             break;
+          case '-':
+            fpar->ref_state_.flags_ |= std::ios::left;
+            break;
+          case '=':
+            fpar->pad_scheme_ |= format_item_t::centered;
+            break;
+          case ' ':
+            fpar->pad_scheme_ |= format_item_t::spacepad;
+            break;
+          case '+':
+            fpar->ref_state_.flags_ |= std::ios::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->ref_state_.flags_ |= std::ios::showpoint | std::ios::showbase;
+            break;
+          default:
+            goto parse_width;
+          }
+        ++i1;
+      } // loop on flag.
+    if( i1>=buf.size()) {
+      maybe_throw_exception(exceptions);
+      return true; 
+    }
+
+  parse_width:
+    // handle width spec
+    skip_asterisk(buf, &i1, os); // skips 'asterisk fields' :  *, or *N$
+    i0 = i1;  // save position before digits
+    while (i1<buf.size() && wrap_isdigit(buf[i1], os))
+      i1++;
+    
+    if (i1!=i0) 
+      { fpar->ref_state_.width_ = str2int( buf,i0, os, std::streamsize(0) ); }
+
+  parse_precision:
+    if( i1>=buf.size()) { 
+      maybe_throw_exception(exceptions);
+      return true;
+    }
+    // handle precision spec
+    if (buf[i1]=='.')  
+      {
+        ++i1;
+        skip_asterisk(buf, &i1, os);
+        i0 = i1;  // save position before digits
+        while (i1<buf.size() && wrap_isdigit(buf[i1], os))
+          ++i1;
+
+        if(i1==i0)
+          fpar->ref_state_.precision_ = 0;
+        else 
+          fpar->ref_state_.precision_ = str2int(buf,i0, os, std::streamsize(0) );
+      }
+    
+    // handle  formatting-type flags :
+    while( i1<buf.size() && 
+           ( buf[i1]=='l' || buf[i1]=='L' || buf[i1]=='h') )
+      ++i1;
+    if( i1>=buf.size()) {
+      maybe_throw_exception(exceptions);
+      return true;
+    }
+    
+    if( in_brackets && buf[i1]=='|' ) 
+      {
+        ++i1;
+        return true;
+      }
+    switch (buf[i1])  
+      {
+      case 'X':
+        fpar->ref_state_.flags_ |= std::ios::uppercase;
+      case 'p': // pointer => set hex.
+      case 'x':
+        fpar->ref_state_.flags_ &= ~std::ios::basefield;
+        fpar->ref_state_.flags_ |= std::ios::hex;
+        break;
+      
+      case 'o':
+        fpar->ref_state_.flags_ &= ~std::ios::basefield;
+        fpar->ref_state_.flags_ |=  std::ios::oct;
+        break;
+
+      case 'E':
+        fpar->ref_state_.flags_ |=  std::ios::uppercase;
+      case 'e':
+        fpar->ref_state_.flags_ &= ~std::ios::floatfield;
+        fpar->ref_state_.flags_ |=  std::ios::scientific;
+
+        fpar->ref_state_.flags_ &= ~std::ios::basefield;
+        fpar->ref_state_.flags_ |=  std::ios::dec;
+        break;
+      
+      case 'f':
+        fpar->ref_state_.flags_ &= ~std::ios::floatfield;
+        fpar->ref_state_.flags_ |=  std::ios::fixed;
+      case 'u':
+      case 'd':
+      case 'i':
+        fpar->ref_state_.flags_ &= ~std::ios::basefield;
+        fpar->ref_state_.flags_ |=  std::ios::dec;
+        break;
+
+      case 'T':
+        ++i1;
+        if( i1 >= buf.size())
+          maybe_throw_exception(exceptions);
+        else
+          fpar->ref_state_.fill_ = buf[i1];
+        fpar->pad_scheme_ |= format_item_t::tabulation;
+        fpar->argN_ = format_item_t::argN_tabulation; 
+        break;
+      case 't': 
+        fpar->ref_state_.fill_ = ' ';
+        fpar->pad_scheme_ |= format_item_t::tabulation;
+        fpar->argN_ = format_item_t::argN_tabulation; 
+        break;
+
+      case 'G':
+        fpar->ref_state_.flags_ |= std::ios::uppercase;
+        break;
+      case 'g': // 'g' conversion is default for floats.
+        fpar->ref_state_.flags_ &= ~std::ios::basefield;
+        fpar->ref_state_.flags_ |=  std::ios::dec;
+
+        // CLEAR all floatield flags, so stream will CHOOSE
+        fpar->ref_state_.flags_ &= ~std::ios::floatfield; 
+        break;
+
+      case 'C':
+      case 'c': 
+        fpar->truncate_ = 1;
+        break;
+      case 'S':
+      case 's': 
+        fpar->truncate_ = fpar->ref_state_.precision_;
+        fpar->ref_state_.precision_ = -1;
+        break;
+      case 'n' :  
+        fpar->argN_ = format_item_t::argN_ignored;
+        break;
+      default: 
+        maybe_throw_exception(exceptions);
+      }
+    ++i1;
+
+    if( in_brackets )
+      {
+        if( i1<buf.size() && buf[i1]=='|' ) 
+          {
+            ++i1;
+            return true;
+          }
+        else  maybe_throw_exception(exceptions);
+      }
+    return true;
+  }
+
+} // detail namespace
+} // io namespace
+
+
+// -----------------------------------------------
+//  format :: parse(..)
+
+void basic_format::parse(const string_t & buf) 
+  // parse the format-string
+{
+    using namespace std;
+    const char arg_mark = '%';
+    bool ordered_args=true; 
+    int max_argN=-1;
+    string_t::size_type i1=0;
+    int num_items=0;
+    
+    // A: find upper_bound on num_items and allocates arrays
+    i1=0; 
+    while( (i1=buf.find(arg_mark,i1)) != string::npos ) 
+    {
+      if( i1+1 >= buf.size() ) {
+        if(exceptions() & io::bad_format_string_bit)
+          boost::throw_exception(io::bad_format_string()); // must not end in "bla bla %"
+        else break; // stop there, ignore last '%'
+      }
+      if(buf[i1+1] == buf[i1] ) { i1+=2; continue; } // escaped "%%" / "##"
+      ++i1;
+      
+      // in case of %N% directives, dont count it double (wastes allocations..) :
+      while(i1 < buf.size() && io::detail::wrap_isdigit(buf[i1],oss_)) ++i1;
+      if( i1 < buf.size() && buf[i1] == arg_mark ) ++ i1;
+
+      ++num_items;
+    }
+    items_.assign( num_items, format_item_t() );
+    
+    // B: Now the real parsing of the format string :
+    num_items=0;
+    i1 = 0;
+    string_t::size_type i0 = i1;
+    bool special_things=false;
+    int cur_it=0;
+    while( (i1=buf.find(arg_mark,i1)) != string::npos ) 
+    {
+      string_t & piece = (cur_it==0) ? prefix_ : items_[cur_it-1].appendix_;
+
+      if( buf[i1+1] == buf[i1] ) // escaped mark, '%%'
+      {
+        piece += buf.substr(i0, i1-i0) + buf[i1]; 
+        i1+=2; i0=i1;
+        continue; 
+      }
+      BOOST_ASSERT(  static_cast<unsigned int>(cur_it) < items_.size() || cur_it==0);
+
+      if(i1!=i0) piece += buf.substr(i0, i1-i0);
+      ++i1;
+      
+      bool parse_ok;
+      parse_ok = io::detail::parse_printf_directive(buf, &i1, &items_[cur_it], oss_, exceptions());
+      if( ! parse_ok ) continue; // the directive will be printed verbatim
+
+      i0=i1;
+      items_[cur_it].compute_states(); // process complex options, like zeropad, into stream params.
+
+      int argN=items_[cur_it].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_it;
+    } // loop on %'s
+    BOOST_ASSERT(cur_it == num_items);
+    
+    // store the final piece of string
+    string_t & piece = (cur_it==0) ? prefix_ : items_[cur_it-1].appendix_;
+    piece += buf.substr(i0);
+    
+    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());
+          // 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);
+
+    if(special_things) style_ |= special_needs;
+    num_args_ = max_argN + 1;
+    if(ordered_args) style_ |=  ordered;
+    else style_ &= ~ordered;
+}
+
+} // namespace boost
+
+
+#endif //  BOOST_FORMAT_PARSING_HPP