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27
28#ifndef DOUBLE_CONVERSION_FAST_DTOA_H_
29#define DOUBLE_CONVERSION_FAST_DTOA_H_
30
31#include "utils.h"
32
33namespace WTF {
34
35namespace double_conversion {
36
37    enum FastDtoaMode {
38        // Computes the shortest representation of the given input. The returned
39        // result will be the most accurate number of this length. Longer
40        // representations might be more accurate.
41        FAST_DTOA_SHORTEST,
42        // Computes a representation where the precision (number of digits) is
43        // given as input. The precision is independent of the decimal point.
44        FAST_DTOA_PRECISION
45    };
46
47    // FastDtoa will produce at most kFastDtoaMaximalLength digits. This does not
48    // include the terminating '\0' character.
49    static const int kFastDtoaMaximalLength = 17;
50
51    // Provides a decimal representation of v.
52    // The result should be interpreted as buffer * 10^(point - length).
53    //
54    // Precondition:
55    //   * v must be a strictly positive finite double.
56    //
57    // Returns true if it succeeds, otherwise the result can not be trusted.
58    // There will be *length digits inside the buffer followed by a null terminator.
59    // If the function returns true and mode equals
60    //   - FAST_DTOA_SHORTEST, then
61    //     the parameter requested_digits is ignored.
62    //     The result satisfies
63    //         v == (double) (buffer * 10^(point - length)).
64    //     The digits in the buffer are the shortest representation possible. E.g.
65    //     if 0.099999999999 and 0.1 represent the same double then "1" is returned
66    //     with point = 0.
67    //     The last digit will be closest to the actual v. That is, even if several
68    //     digits might correctly yield 'v' when read again, the buffer will contain
69    //     the one closest to v.
70    //   - FAST_DTOA_PRECISION, then
71    //     the buffer contains requested_digits digits.
72    //     the difference v - (buffer * 10^(point-length)) is closest to zero for
73    //     all possible representations of requested_digits digits.
74    //     If there are two values that are equally close, then FastDtoa returns
75    //     false.
76    // For both modes the buffer must be large enough to hold the result.
77    bool FastDtoa(double d,
78                  FastDtoaMode mode,
79                  int requested_digits,
80                  Vector<char> buffer,
81                  int* length,
82                  int* decimal_point);
83
84}  // namespace double_conversion
85
86} // namespace WTF
87
88#endif  // DOUBLE_CONVERSION_FAST_DTOA_H_
89