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/* * Mode: C++; tabwidth: 8; indenttabsmode: nil; cbasicoffset: 4 *
* vim: set ts=8 sts=4 et sw=4 tw=99:
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef jsdtoa_h
#define jsdtoa_h
/*
* Public interface to portable doubleprecision floating point to string
* and back conversion package.
*/
#include <stddef.h>
struct DtoaState;
namespace js {
extern DtoaState*
NewDtoaState();
extern void
DestroyDtoaState(DtoaState* state);
} // namespace js
/*
* js_strtod_harder() returns as a doubleprecision floatingpoint number the
* value represented by the character string pointed to by s00. The string is
* scanned up to the first unrecognized character.
*
* If se is not nullptr, *se receives a pointer to the character terminating
* the scan. If no number can be formed, *se receives a pointer to the first
* unparseable character in s00, and zero is returned.
*
* On overflow, this function returns infinity and does not indicate an error.
*
* *err is set to zero on success; it's set to JS_DTOA_ENOMEM on memory failure.
*/
#define JS_DTOA_ENOMEM 2
double
js_strtod_harder(DtoaState* state, const char* s00, char** se, int* err);
/*
* Modes for converting floatingpoint numbers to strings.
*
* Some of the modes can roundtrip; this means that if the number is converted to
* a string using one of these mode and then converted back to a number, the result
* will be identical to the original number (except that, due to ECMA, 0 will get converted
* to +0). These roundtrip modes return the minimum number of significand digits that
* permit the round trip.
*
* Some of the modes take an integer parameter <precision>.
*/
/* NB: Keep this in sync with number_constants[]. */
typedef enum JSDToStrMode {
DTOSTR_STANDARD, /* Either fixed or exponential format; roundtrip */
DTOSTR_STANDARD_EXPONENTIAL, /* Always exponential format; roundtrip */
DTOSTR_FIXED, /* Round to <precision> digits after the decimal point; exponential if number is large */
DTOSTR_EXPONENTIAL, /* Always exponential format; <precision> significant digits */
DTOSTR_PRECISION /* Either fixed or exponential format; <precision> significant digits */
} JSDToStrMode;
/* Maximum number of characters (including trailing null) that a DTOSTR_STANDARD or DTOSTR_STANDARD_EXPONENTIAL
* conversion can produce. This maximum is reached for a number like 0.0000012345678901234567. */
#define DTOSTR_STANDARD_BUFFER_SIZE 26
/* Maximum number of characters (including trailing null) that one of the other conversions
* can produce. This maximum is reached for TO_FIXED, which can generate up to 21 digits before the decimal point. */
#define DTOSTR_VARIABLE_BUFFER_SIZE(precision) ((precision)+24 > DTOSTR_STANDARD_BUFFER_SIZE ? (precision)+24 : DTOSTR_STANDARD_BUFFER_SIZE)
/*
* DO NOT USE THIS FUNCTION IF YOU CAN AVOID IT. js::NumberToCString() is a
* better function to use.
*
* Convert dval according to the given mode and return a pointer to the
* resulting ASCII string. If mode == DTOSTR_STANDARD and precision == 0 it's
* equivalent to ToString() as specified by ECMA2625 section 9.8.1, but it
* doesn't handle integers specially so should be avoided in that case (that's
* why js::NumberToCString() is better).
*
* The result is held somewhere in buffer, but not necessarily at the
* beginning. The size of buffer is given in bufferSize, and must be at least
* as large as given by the above macros.
*
* Return nullptr if out of memory.
*/
char*
js_dtostr(DtoaState* state, char* buffer, size_t bufferSize, JSDToStrMode mode, int precision,
double dval);
/*
* DO NOT USE THIS FUNCTION IF YOU CAN AVOID IT. js::NumberToCString() is a
* better function to use.
*
* Convert d to a string in the given base. The integral part of d will be
* printed exactly in that base, regardless of how large it is, because there
* is no exponential notation for nonbaseten numbers. The fractional part
* will be rounded to as few digits as possible while still preserving the
* roundtrip property (analogous to that of printing decimal numbers). In
* other words, if one were to read the resulting string in via a hypothetical
* basenumberreading routine that rounds to the nearest IEEE double (and to
* an even significand if there are two equally near doubles), then the result
* would equal d (except for 0.0, which converts to "0", and NaN, which is
* not equal to itself).
*
* Return nullptr if out of memory. If the result is not nullptr, it must be
* released via js_free().
*/
char*
js_dtobasestr(DtoaState* state, int base, double d);
#endif /* jsdtoa_h */
