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micropython/py/parsenum.c

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C
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/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2013, 2014 Damien P. George
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include <stdbool.h>
#include <stdlib.h>
#include "py/runtime.h"
#include "py/parsenumbase.h"
#include "py/parsenum.h"
#include "py/smallint.h"
#if MICROPY_PY_BUILTINS_FLOAT
#include <math.h>
#endif
STATIC NORETURN void raise_exc(mp_obj_t exc, mp_lexer_t *lex) {
// if lex!=NULL then the parser called us and we need to convert the
// exception's type from ValueError to SyntaxError and add traceback info
if (lex != NULL) {
((mp_obj_base_t*)MP_OBJ_TO_PTR(exc))->type = &mp_type_SyntaxError;
mp_obj_exception_add_traceback(exc, lex->source_name, lex->tok_line, MP_QSTR_NULL);
}
nlr_raise(exc);
}
mp_obj_t mp_parse_num_integer(const char *restrict str_, size_t len, int base, mp_lexer_t *lex) {
const byte *restrict str = (const byte *)str_;
const byte *restrict top = str + len;
bool neg = false;
mp_obj_t ret_val;
// check radix base
if ((base != 0 && base < 2) || base > 36) {
// this won't be reached if lex!=NULL
mp_raise_ValueError("int() arg 2 must be >= 2 and <= 36");
}
// skip leading space
for (; str < top && unichar_isspace(*str); str++) {
}
// parse optional sign
if (str < top) {
if (*str == '+') {
str++;
} else if (*str == '-') {
str++;
neg = true;
}
}
// parse optional base prefix
str += mp_parse_num_base((const char*)str, top - str, &base);
// string should be an integer number
mp_int_t int_val = 0;
const byte *restrict str_val_start = str;
for (; str < top; str++) {
// get next digit as a value
mp_uint_t dig = *str;
if ('0' <= dig && dig <= '9') {
dig -= '0';
} else if (dig == '_') {
continue;
} else {
dig |= 0x20; // make digit lower-case
if ('a' <= dig && dig <= 'z') {
dig -= 'a' - 10;
} else {
// unknown character
break;
}
}
if (dig >= (mp_uint_t)base) {
break;
}
// add next digi and check for overflow
if (mp_small_int_mul_overflow(int_val, base)) {
goto overflow;
}
int_val = int_val * base + dig;
if (!MP_SMALL_INT_FITS(int_val)) {
goto overflow;
}
}
// negate value if needed
if (neg) {
int_val = -int_val;
}
// create the small int
ret_val = MP_OBJ_NEW_SMALL_INT(int_val);
have_ret_val:
// check we parsed something
if (str == str_val_start) {
goto value_error;
}
// skip trailing space
for (; str < top && unichar_isspace(*str); str++) {
}
// check we reached the end of the string
if (str != top) {
goto value_error;
}
// return the object
return ret_val;
overflow:
// reparse using long int
{
const char *s2 = (const char*)str_val_start;
ret_val = mp_obj_new_int_from_str_len(&s2, top - str_val_start, neg, base);
str = (const byte*)s2;
goto have_ret_val;
}
value_error:
if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
mp_obj_t exc = mp_obj_new_exception_msg(&mp_type_ValueError,
"invalid syntax for integer");
raise_exc(exc, lex);
} else if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_NORMAL) {
mp_obj_t exc = mp_obj_new_exception_msg_varg(&mp_type_ValueError,
"invalid syntax for integer with base %d", base);
raise_exc(exc, lex);
} else {
vstr_t vstr;
mp_print_t print;
vstr_init_print(&vstr, 50, &print);
mp_printf(&print, "invalid syntax for integer with base %d: ", base);
mp_str_print_quoted(&print, str_val_start, top - str_val_start, true);
mp_obj_t exc = mp_obj_new_exception_arg1(&mp_type_ValueError,
mp_obj_new_str_from_vstr(&mp_type_str, &vstr));
raise_exc(exc, lex);
}
}
typedef enum {
PARSE_DEC_IN_INTG,
PARSE_DEC_IN_FRAC,
PARSE_DEC_IN_EXP,
} parse_dec_in_t;
mp_obj_t mp_parse_num_decimal(const char *str, size_t len, bool allow_imag, bool force_complex, mp_lexer_t *lex) {
#if MICROPY_PY_BUILTINS_FLOAT
// DEC_VAL_MAX only needs to be rough and is used to retain precision while not overflowing
// SMALL_NORMAL_VAL is the smallest power of 10 that is still a normal float
// EXACT_POWER_OF_10 is the largest value of x so that 10^x can be stored exactly in a float
// Note: EXACT_POWER_OF_10 is at least floor(log_5(2^mantissa_length)). Indeed, 10^n = 2^n * 5^n
// so we only have to store the 5^n part in the mantissa (the 2^n part will go into the float's
// exponent).
#if MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_FLOAT
#define DEC_VAL_MAX 1e20F
#define SMALL_NORMAL_VAL (1e-37F)
#define SMALL_NORMAL_EXP (-37)
#define EXACT_POWER_OF_10 (9)
#elif MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_DOUBLE
#define DEC_VAL_MAX 1e200
#define SMALL_NORMAL_VAL (1e-307)
#define SMALL_NORMAL_EXP (-307)
#define EXACT_POWER_OF_10 (22)
#endif
const char *top = str + len;
mp_float_t dec_val = 0;
bool dec_neg = false;
bool imag = false;
// skip leading space
for (; str < top && unichar_isspace(*str); str++) {
}
// parse optional sign
if (str < top) {
if (*str == '+') {
str++;
} else if (*str == '-') {
str++;
dec_neg = true;
}
}
const char *str_val_start = str;
// determine what the string is
if (str < top && (str[0] | 0x20) == 'i') {
// string starts with 'i', should be 'inf' or 'infinity' (case insensitive)
if (str + 2 < top && (str[1] | 0x20) == 'n' && (str[2] | 0x20) == 'f') {
// inf
str += 3;
dec_val = INFINITY;
if (str + 4 < top && (str[0] | 0x20) == 'i' && (str[1] | 0x20) == 'n' && (str[2] | 0x20) == 'i' && (str[3] | 0x20) == 't' && (str[4] | 0x20) == 'y') {
// infinity
str += 5;
}
}
} else if (str < top && (str[0] | 0x20) == 'n') {
// string starts with 'n', should be 'nan' (case insensitive)
if (str + 2 < top && (str[1] | 0x20) == 'a' && (str[2] | 0x20) == 'n') {
// NaN
str += 3;
dec_val = MICROPY_FLOAT_C_FUN(nan)("");
}
} else {
// string should be a decimal number
parse_dec_in_t in = PARSE_DEC_IN_INTG;
bool exp_neg = false;
int exp_val = 0;
int exp_extra = 0;
while (str < top) {
unsigned int dig = *str++;
if ('0' <= dig && dig <= '9') {
dig -= '0';
if (in == PARSE_DEC_IN_EXP) {
// don't overflow exp_val when adding next digit, instead just truncate
// it and the resulting float will still be correct, either inf or 0.0
// (use INT_MAX/2 to allow adding exp_extra at the end without overflow)
if (exp_val < (INT_MAX / 2 - 9) / 10) {
exp_val = 10 * exp_val + dig;
}
} else {
if (dec_val < DEC_VAL_MAX) {
// dec_val won't overflow so keep accumulating
dec_val = 10 * dec_val + dig;
if (in == PARSE_DEC_IN_FRAC) {
--exp_extra;
}
} else {
// dec_val might overflow and we anyway can't represent more digits
// of precision, so ignore the digit and just adjust the exponent
if (in == PARSE_DEC_IN_INTG) {
++exp_extra;
}
}
}
} else if (in == PARSE_DEC_IN_INTG && dig == '.') {
in = PARSE_DEC_IN_FRAC;
} else if (in != PARSE_DEC_IN_EXP && ((dig | 0x20) == 'e')) {
in = PARSE_DEC_IN_EXP;
if (str < top) {
if (str[0] == '+') {
str++;
} else if (str[0] == '-') {
str++;
exp_neg = true;
}
}
if (str == top) {
goto value_error;
}
} else if (allow_imag && (dig | 0x20) == 'j') {
imag = true;
break;
} else if (dig == '_') {
continue;
} else {
// unknown character
str--;
break;
}
}
// work out the exponent
if (exp_neg) {
exp_val = -exp_val;
}
// apply the exponent, making sure it's not a subnormal value
exp_val += exp_extra;
if (exp_val < SMALL_NORMAL_EXP) {
exp_val -= SMALL_NORMAL_EXP;
dec_val *= SMALL_NORMAL_VAL;
}
// At this point, we need to multiply the mantissa by its base 10 exponent. If possible,
// we would rather manipulate numbers that have an exact representation in IEEE754. It
// turns out small positive powers of 10 do, whereas small negative powers of 10 don't.
// So in that case, we'll yield a division of exact values rather than a multiplication
// of slightly erroneous values.
if (exp_val < 0 && exp_val >= -EXACT_POWER_OF_10) {
dec_val /= MICROPY_FLOAT_C_FUN(pow)(10, -exp_val);
} else {
dec_val *= MICROPY_FLOAT_C_FUN(pow)(10, exp_val);
}
}
// negate value if needed
if (dec_neg) {
dec_val = -dec_val;
}
// check we parsed something
if (str == str_val_start) {
goto value_error;
}
// skip trailing space
for (; str < top && unichar_isspace(*str); str++) {
}
// check we reached the end of the string
if (str != top) {
goto value_error;
}
// return the object
#if MICROPY_PY_BUILTINS_COMPLEX
if (imag) {
return mp_obj_new_complex(0, dec_val);
} else if (force_complex) {
return mp_obj_new_complex(dec_val, 0);
}
#else
if (imag || force_complex) {
raise_exc(mp_obj_new_exception_msg(&mp_type_ValueError, "complex values not supported"), lex);
}
#endif
else {
return mp_obj_new_float(dec_val);
}
value_error:
raise_exc(mp_obj_new_exception_msg(&mp_type_ValueError, "invalid syntax for number"), lex);
#else
raise_exc(mp_obj_new_exception_msg(&mp_type_ValueError, "decimal numbers not supported"), lex);
#endif
}
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