js/src/jsdtoa.h

   1 /* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
   2  *
   3  * ***** BEGIN LICENSE BLOCK *****
   4  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
   5  *
   6  * The contents of this file are subject to the Mozilla Public License Version
   7  * 1.1 (the "License"); you may not use this file except in compliance with
   8  * the License. You may obtain a copy of the License at
   9  * http://www.mozilla.org/MPL/
  10  *
  11  * Software distributed under the License is distributed on an "AS IS" basis,
  12  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
  13  * for the specific language governing rights and limitations under the
  14  * License.
  15  *
  16  * The Original Code is Mozilla Communicator client code, released
  17  * March 31, 1998.
  18  *
  19  * The Initial Developer of the Original Code is
  20  * Netscape Communications Corporation.
  21  * Portions created by the Initial Developer are Copyright (C) 1998
  22  * the Initial Developer. All Rights Reserved.
  23  *
  24  * Contributor(s):
  25  *
  26  * Alternatively, the contents of this file may be used under the terms of
  27  * either of the GNU General Public License Version 2 or later (the "GPL"),
  28  * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
  29  * in which case the provisions of the GPL or the LGPL are applicable instead
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  36  * the terms of any one of the MPL, the GPL or the LGPL.
  37  *
  38  * ***** END LICENSE BLOCK ***** */
  39
  40 #ifndef jsdtoa_h___
  41 #define jsdtoa_h___
  42 /*
  43  * Public interface to portable double-precision floating point to string
  44  * and back conversion package.
  45  */
  46
  47 #include "jscompat.h"
  48
  49 JS_BEGIN_EXTERN_C
  50
  51 struct DtoaState;
  52
  53 DtoaState *
  54 js_NewDtoaState();
  55
  56 void
  57 js_DestroyDtoaState(DtoaState *state);
  58
  59 /*
  60  * js_strtod_harder() returns as a double-precision floating-point number the
  61  * value represented by the character string pointed to by s00. The string is
  62  * scanned up to the first unrecognized character.
  63  *
  64  * If se is not NULL, *se receives a pointer to the character terminating the
  65  * scan. If no number can be formed, *se receives a pointer to the first
  66  * unparseable character in s00, and zero is returned.
  67  *
  68  * *err is set to zero on success; it's set to JS_DTOA_ERANGE on range
  69  * errors and JS_DTOA_ENOMEM on memory failure.
  70  */
  71 #define JS_DTOA_ERANGE 1
  72 #define JS_DTOA_ENOMEM 2
  73 double
  74 js_strtod_harder(DtoaState *state, const char *s00, char **se, int *err);
  75
  76 /*
  77  * Modes for converting floating-point numbers to strings.
  78  *
  79  * Some of the modes can round-trip; this means that if the number is converted to
  80  * a string using one of these mode and then converted back to a number, the result
  81  * will be identical to the original number (except that, due to ECMA, -0 will get converted
  82  * to +0).  These round-trip modes return the minimum number of significand digits that
  83  * permit the round trip.
  84  *
  85  * Some of the modes take an integer parameter <precision>.
  86  */
  87 /* NB: Keep this in sync with number_constants[]. */
  88 typedef enum JSDToStrMode {
  89     DTOSTR_STANDARD,              /* Either fixed or exponential format; round-trip */
  90     DTOSTR_STANDARD_EXPONENTIAL,  /* Always exponential format; round-trip */
  91     DTOSTR_FIXED,                 /* Round to <precision> digits after the decimal point; exponential if number is large */
  92     DTOSTR_EXPONENTIAL,           /* Always exponential format; <precision> significant digits */
  93     DTOSTR_PRECISION              /* Either fixed or exponential format; <precision> significant digits */
  94 } JSDToStrMode;
  95
  96
  97 /* Maximum number of characters (including trailing null) that a DTOSTR_STANDARD or DTOSTR_STANDARD_EXPONENTIAL
  98  * conversion can produce.  This maximum is reached for a number like -0.0000012345678901234567. */
  99 #define DTOSTR_STANDARD_BUFFER_SIZE 26
 100
 101 /* Maximum number of characters (including trailing null) that one of the other conversions
 102  * can produce.  This maximum is reached for TO_FIXED, which can generate up to 21 digits before the decimal point. */
 103 #define DTOSTR_VARIABLE_BUFFER_SIZE(precision) ((precision)+24 > DTOSTR_STANDARD_BUFFER_SIZE ? (precision)+24 : DTOSTR_STANDARD_BUFFER_SIZE)
 104
 105 /*
 106  * DO NOT USE THIS FUNCTION IF YOU CAN AVOID IT.  js::NumberToCString() is a
 107  * better function to use.
 108  *
 109  * Convert dval according to the given mode and return a pointer to the
 110  * resulting ASCII string.  If mode == DTOSTR_STANDARD and precision == 0 it's
 111  * equivalent to ToString() as specified by ECMA-262-5 section 9.8.1, but it
 112  * doesn't handle integers specially so should be avoided in that case (that's
 113  * why js::NumberToCString() is better).
 114  *
 115  * The result is held somewhere in buffer, but not necessarily at the
 116  * beginning.  The size of buffer is given in bufferSize, and must be at least
 117  * as large as given by the above macros.
 118  *
 119  * Return NULL if out of memory.
 120  */
 121 char *
 122 js_dtostr(DtoaState *state, char *buffer, size_t bufferSize, JSDToStrMode mode, int precision,
 123           double dval);
 124
 125 /*
 126  * DO NOT USE THIS FUNCTION IF YOU CAN AVOID IT.  js::NumberToCString() is a
 127  * better function to use.
 128  *
 129  * Convert d to a string in the given base.  The integral part of d will be
 130  * printed exactly in that base, regardless of how large it is, because there
 131  * is no exponential notation for non-base-ten numbers.  The fractional part
 132  * will be rounded to as few digits as possible while still preserving the
 133  * round-trip property (analogous to that of printing decimal numbers).  In
 134  * other words, if one were to read the resulting string in via a hypothetical
 135  * base-number-reading routine that rounds to the nearest IEEE double (and to
 136  * an even significand if there are two equally near doubles), then the result
 137  * would equal d (except for -0.0, which converts to "0", and NaN, which is
 138  * not equal to itself).
 139  *
 140  * Return NULL if out of memory.  If the result is not NULL, it must be
 141  * released via js_free().
 142  */
 143 char *
 144 js_dtobasestr(DtoaState *state, int base, double d);
 145
 146 JS_END_EXTERN_C
 147
 148 #endif /* jsdtoa_h___ */