src/rational/input/cl_RA_read.cc

   1 // read_rational().
   2 // This file contains a slimmed down version of read_real().
   3 // It does not pull in all the floating-point, complex and transcendental
   4 // function code.
   5
   6 // General includes.
   7 #include "base/cl_sysdep.h"
   8
   9 // Specification.
  10 #include "cln/rational_io.h"
  11
  12
  13 // Implementation.
  14
  15 #include <cstring>
  16 #include <sstream>
  17 #include "cln/input.h"
  18 #include "cln/integer.h"
  19 #include "cln/integer_io.h"
  20 #include "integer/cl_I.h"
  21 #include "cln/exception.h"
  22
  23 namespace cln {
  24
  25 // Step forward over all digits, to the end of string or to the next non-digit.
  26 static const char * skip_digits (const char * ptr, const char * string_limit, unsigned int base)
  27 {
  28         for ( ; ptr != string_limit; ptr++) {
  29                 var char ch = *ptr;
  30                 if ((ch >= '0') && (ch <= '9'))
  31                         if (ch < '0' + (int)base)
  32                                 continue;
  33                         else
  34                                 break;
  35                 else {
  36                         if (base <= 10)
  37                                 break;
  38                         if (((ch >= 'A') && (ch < 'A'-10+(int)base))
  39                             || ((ch >= 'a') && (ch < 'a'-10+(int)base))
  40                            )
  41                                 continue;
  42                         else
  43                                 break;
  44                 }
  45         }
  46         return ptr;
  47 }
  48
  49 #define at_end_of_parse(ptr)  \
  50   if (end_of_parse)                                                     \
  51     { *end_of_parse = (ptr); }                                          \
  52   else                                                                  \
  53     { if ((ptr) != string_limit) { throw read_number_junk_exception((ptr),string,string_limit); } }
  54
  55 const cl_RA read_rational (const cl_read_flags& flags, const char * string, const char * string_limit, const char * * end_of_parse)
  56 {
  57         ASSERT((flags.syntax & ~(syntax_rational|syntax_maybe_bad)) == 0);
  58         // If no string_limit is given, it defaults to the end of the string.
  59         if (!string_limit)
  60                 string_limit = string + ::strlen(string);
  61         if (flags.syntax & syntax_rational) {
  62                 // Check for rational number syntax.
  63                 var unsigned int rational_base = flags.rational_base;
  64                 var const char * ptr = string;
  65                 if (flags.lsyntax & lsyntax_commonlisp) {
  66                         if (ptr == string_limit) goto not_rational_syntax;
  67                         if (*ptr == '#') {
  68                                 // Check for #b, #o, #x, #nR syntax.
  69                                 ptr++;
  70                                 if (ptr == string_limit) goto not_rational_syntax;
  71                                 switch (*ptr) {
  72                                 case 'b': case 'B':
  73                                         rational_base = 2; break;
  74                                 case 'o': case 'O':
  75                                         rational_base = 8; break;
  76                                 case 'x': case 'X':
  77                                         rational_base = 16; break;
  78                                 default:
  79                                         var const char * base_end_ptr =
  80                                                 skip_digits(ptr,string_limit,10);
  81                                         if (base_end_ptr == ptr) goto not_rational_syntax;
  82                                         if (base_end_ptr == string_limit) goto not_rational_syntax;
  83                                         if (!((*base_end_ptr == 'r') || (*base_end_ptr == 'R')))
  84                                                 goto not_rational_syntax;
  85                                         var cl_I base = read_integer(10,0,ptr,0,base_end_ptr-ptr);
  86                                         if (!((base >= 2) && (base <= 36))) {
  87                                                 std::ostringstream buf;
  88                                                 fprint(buf, "Base must be an integer in the range from 2 to 36, not ");
  89                                                 fprint(buf, base);
  90                                                 throw runtime_exception(buf.str());
  91                                         }
  92                                         rational_base = FN_to_UV(base); ptr = base_end_ptr;
  93                                         break;
  94                                 }
  95                                 ptr++;
  96                         }
  97                 }
  98                 var const char * ptr_after_prefix = ptr;
  99                 var cl_signean sign = 0;
 100                 if (ptr == string_limit) goto not_rational_syntax;
 101                 switch (*ptr) {
 102                         case '-': sign = ~sign;
 103                         case '+': ptr++;
 104                         default: break;
 105                 }
 106                 var const char * ptr_after_sign = ptr;
 107                 if (flags.syntax & syntax_integer) {
 108                         // Check for integer syntax:  {'+'|'-'|} {digit}+ {'.'|}
 109                         // Allow final dot only in Common Lisp syntax if there was no #<base> prefix.
 110                         if ((flags.lsyntax & lsyntax_commonlisp) && (ptr_after_prefix == string)) {
 111                                 ptr = skip_digits(ptr_after_sign,string_limit,10);
 112                                 if (ptr != ptr_after_sign)
 113                                   if (ptr != string_limit)
 114                                     if (*ptr == '.') {
 115                                         ptr++;
 116                                         if ((ptr == string_limit) || !(((*ptr >= '0') && (*ptr <= '9')) || ((*ptr >= 'A') && (*ptr <= 'Z') && (*ptr != 'I')) || ((*ptr >= 'a') && (*ptr <= 'z') && (*ptr != 'i')) || (*ptr == '.') || (*ptr == '_') || (*ptr == '/'))) {
 117                                                 at_end_of_parse(ptr);
 118                                                 return read_integer(10,sign,ptr_after_sign,0,ptr-ptr_after_sign);
 119                                         }
 120                                 }
 121                         }
 122                         ptr = skip_digits(ptr_after_sign,string_limit,rational_base);
 123                         if ((ptr == string_limit) || !(((*ptr >= '0') && (*ptr <= '9')) || ((*ptr >= 'A') && (*ptr <= 'Z') && (*ptr != 'I')) || ((*ptr >= 'a') && (*ptr <= 'z') && (*ptr != 'i')) || (*ptr == '.') || (*ptr == '_') || (*ptr == '/'))) {
 124                                 at_end_of_parse(ptr);
 125                                 return read_integer(rational_base,sign,ptr_after_sign,0,ptr-ptr_after_sign);
 126                         }
 127                 }
 128                 if (flags.syntax & syntax_ratio) {
 129                         // Check for ratio syntax: {'+'|'-'|} {digit}+ '/' {digit}+
 130                         ptr = skip_digits(ptr_after_sign,string_limit,rational_base);
 131                         if (ptr != ptr_after_sign)
 132                           if (ptr != string_limit)
 133                             if (*ptr == '/') {
 134                                 var const char * ptr_at_slash = ptr;
 135                                 ptr = skip_digits(ptr_at_slash+1,string_limit,rational_base);
 136                                 if (ptr != ptr_at_slash+1)
 137                                   if ((ptr == string_limit) || !(((*ptr >= '0') && (*ptr <= '9')) || ((*ptr >= 'A') && (*ptr <= 'Z') && (*ptr != 'I')) || ((*ptr >= 'a') && (*ptr <= 'z') && (*ptr != 'i')) || (*ptr == '.') || (*ptr == '_') || (*ptr == '/'))) {
 138                                         at_end_of_parse(ptr);
 139                                         return read_rational(rational_base,sign,ptr_after_sign,0,ptr_at_slash-ptr_after_sign,ptr-ptr_after_sign);
 140                                 }
 141                         }
 142                 }
 143         }
 144 not_rational_syntax:
 145         if (flags.syntax & syntax_maybe_bad) {
 146                 ASSERT(end_of_parse);
 147                 *end_of_parse = string;
 148                 return 0; // dummy return
 149         }
 150         throw read_number_bad_syntax_exception(string,string_limit);
 151 }
 152
 153 }  // namespace cln