src/complex/input/cl_N_read_stream.cc

   1 // read_complex().
   2
   3 // General includes.
   4 #include "base/cl_sysdep.h"
   5
   6 // Specification.
   7 #include "cln/complex_io.h"
   8
   9
  10 // Implementation.
  11
  12 #include "cln/io.h"
  13 #include "base/string/cl_spushstring.h"
  14 #include "cln/input.h"
  15
  16 namespace cln {
  17
  18 // We read an entire token (or even more, if it begins with #C) into a
  19 // buffer and then call read_complex() on the buffer.
  20
  21 class pushstring_hack : public cl_spushstring {
  22 public:
  23         char* start_pointer (void) { return buffer; }
  24         char* end_pointer (void) { return buffer+index; }
  25 };
  26
  27 static bool number_char_p (char c)
  28 {
  29         if ((c >= '0') && (c <= '9'))
  30                 return true;
  31         if (((c >= 'A') && (c <= 'Z')) || ((c >= 'a') && (c <= 'z')))
  32                 return true;
  33         switch (c) {
  34                 case '+': case '-': case '.': case '_': case '/':
  35                         return true;
  36                 default:
  37                         return false;
  38         }
  39 }
  40
  41 const cl_N read_complex (std::istream& stream, const cl_read_flags& flags)
  42 {
  43         // One pre-allocated buffer. This reduces the allocation/free cost.
  44         static pushstring_hack buffer;
  45
  46         var int c;
  47         // Skip whitespace at the beginning.
  48         loop {
  49                 c = stream.get();
  50                 if (stream.eof() || stream.fail()) goto eof;
  51                 if ((c == ' ') || (c == '\t') || (c == '\n'))
  52                         continue;
  53                 else
  54                         break;
  55         }
  56         // Found first non-whitespace character.
  57         // Numbers cannot cross lines. We can treat EOF and '\n' the same way.
  58         buffer.reset();
  59         if (c == '#') {
  60                 if (!(flags.lsyntax & lsyntax_commonlisp))
  61                         goto syntax1;
  62                 buffer.push(c);
  63                 // Read some digits, then a letter, then a list or token.
  64                 loop {
  65                         c = stream.get();
  66                         if (stream.eof() || stream.fail()) goto eof;
  67                         buffer.push(c);
  68                         if ((c >= '0') && (c <= '9'))
  69                                 continue;
  70                         else
  71                                 break;
  72                 }
  73                 if (!(((c >= 'A') && (c <= 'Z')) || ((c >= 'a') && (c <= 'z'))))
  74                         goto syntax1;
  75                 c = stream.get();
  76                 if (stream.eof() || stream.fail()) goto eof;
  77                 if (c == '(') {
  78                         var uintL paren_level = 0;
  79                         loop {
  80                                 buffer.push(c);
  81                                 if (c == '(') paren_level++;
  82                                 else if (c == ')') paren_level--;
  83                                 if (paren_level == 0) goto done;
  84                                 c = stream.get();
  85                                 if (stream.eof() || stream.fail() || c == '\n') goto syntax;
  86                         }
  87                 }
  88         }
  89         // Read a number token.
  90         if (!number_char_p(c))
  91                 goto syntax1;
  92         loop {
  93                 buffer.push(c);
  94                 c = stream.peek();  // Avoid fail state on EOF.
  95                 if (stream.eof() || stream.fail() || !number_char_p(c))
  96                         break;
  97                 c = stream.get();
  98         }
  99 done:
 100         // Parse the number.
 101         return read_complex(flags,
 102                             buffer.start_pointer(), buffer.end_pointer(),
 103                             NULL
 104                            );
 105
 106         // Handle syntax error.
 107 syntax1:        buffer.push(c);
 108 syntax: throw read_number_bad_syntax_exception(buffer.start_pointer(),buffer.end_pointer());
 109
 110         // Handle premature EOF.
 111 eof:    throw read_number_eof_exception();
 112 }
 113
 114 }  // namespace cln