src/float/input/cl_F_read_stream.cc

   1 // read_float().
   2 // This file contains a slimmed down version of read_real().
   3 // It does not pull in all the generic real number code.
   4
   5 // General includes.
   6 #include "base/cl_sysdep.h"
   7
   8 // Specification.
   9 #include "cln/float_io.h"
  10
  11
  12 // Implementation.
  13
  14 #include "cln/input.h"
  15 #include "cln/io.h"
  16 #include "base/string/cl_spushstring.h"
  17
  18 namespace cln {
  19
  20 // We read an entire token (or even more, if it begins with #C) into a
  21 // buffer and then call read_float() on the buffer.
  22
  23 class pushstring_hack : public cl_spushstring {
  24 public:
  25         char* start_pointer (void) { return buffer; }
  26         char* end_pointer (void) { return buffer+index; }
  27 };
  28
  29 static bool number_char_p (char c)
  30 {
  31         if ((c >= '0') && (c <= '9'))
  32                 return true;
  33         if (((c >= 'A') && (c <= 'Z')) || ((c >= 'a') && (c <= 'z')))
  34                 return true;
  35         switch (c) {
  36                 case '+': case '-': case '.': case '_': case '/':
  37                         return true;
  38                 default:
  39                         return false;
  40         }
  41 }
  42
  43 const cl_F read_float (std::istream& stream, const cl_read_flags& flags)
  44 {
  45         // One pre-allocated buffer. This reduces the allocation/free cost.
  46         static pushstring_hack buffer;
  47
  48         var int c;
  49         // Skip whitespace at the beginning.
  50         loop {
  51                 c = freadchar(stream);
  52                 if (c == cl_EOF) goto eof;
  53                 if ((c == ' ') || (c == '\t') || (c == '\n'))
  54                         continue;
  55                 else
  56                         break;
  57         }
  58         // Found first non-whitespace character.
  59         // Numbers cannot cross lines. We can treat EOF and '\n' the same way.
  60         buffer.reset();
  61         if (c == '#') {
  62                 if (!(flags.lsyntax & lsyntax_commonlisp))
  63                         goto syntax1;
  64                 buffer.push(c);
  65                 // Read some digits, then a letter, then a token.
  66                 loop {
  67                         c = freadchar(stream);
  68                         if (c == cl_EOF) goto eof;
  69                         buffer.push(c);
  70                         if ((c >= '0') && (c <= '9'))
  71                                 continue;
  72                         else
  73                                 break;
  74                 }
  75                 if (!(((c >= 'A') && (c <= 'Z')) || ((c >= 'a') && (c <= 'z'))))
  76                         goto syntax1;
  77                 c = freadchar(stream);
  78                 if (c == cl_EOF) goto eof;
  79         }
  80         // Read a number token.
  81         if (!number_char_p(c))
  82                 goto syntax1;
  83         loop {
  84                 buffer.push(c);
  85                 c = freadchar(stream);
  86                 if (c == cl_EOF)
  87                         break;
  88                 if (!number_char_p(c)) {
  89                         funreadchar(stream,c);
  90                         break;
  91                 }
  92         }
  93         // Parse the number.
  94         return read_float(flags,
  95                           buffer.start_pointer(), buffer.end_pointer(),
  96                           NULL
  97                          );
  98
  99         // Handle syntax error.
 100 syntax1:        buffer.push(c);
 101         throw read_number_bad_syntax_exception(buffer.start_pointer(),buffer.end_pointer());
 102
 103         // Handle premature EOF.
 104 eof:    throw read_number_eof_exception();
 105 }
 106
 107 }  // namespace cln