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