/cln-1.3.2/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
 23namespace cln {
 24
 25// Step forward over all digits, to the end of string or to the next non-digit.
 26static 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
 55const 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	}
144not_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