cobalt / cobalt / d091d43cec3c83208e5995c85db1fd212391cc45 / . / src / v8 / src / numbers / bignum-dtoa.h

// Copyright 2010 the V8 project authors. All rights reserved. | |

// Use of this source code is governed by a BSD-style license that can be | |

// found in the LICENSE file. | |

#ifndef V8_NUMBERS_BIGNUM_DTOA_H_ | |

#define V8_NUMBERS_BIGNUM_DTOA_H_ | |

#include "src/utils/vector.h" | |

namespace v8 { | |

namespace internal { | |

enum BignumDtoaMode { | |

// Return the shortest correct representation. | |

// For example the output of 0.299999999999999988897 is (the less accurate but | |

// correct) 0.3. | |

BIGNUM_DTOA_SHORTEST, | |

// Return a fixed number of digits after the decimal point. | |

// For instance fixed(0.1, 4) becomes 0.1000 | |

// If the input number is big, the output will be big. | |

BIGNUM_DTOA_FIXED, | |

// Return a fixed number of digits, no matter what the exponent is. | |

BIGNUM_DTOA_PRECISION | |

}; | |

// Converts the given double 'v' to ASCII. | |

// The result should be interpreted as buffer * 10^(point-length). | |

// The buffer will be null-terminated. | |

// | |

// The input v must be > 0 and different from NaN, and Infinity. | |

// | |

// The output depends on the given mode: | |

// - SHORTEST: produce the least amount of digits for which the internal | |

// identity requirement is still satisfied. If the digits are printed | |

// (together with the correct exponent) then reading this number will give | |

// 'v' again. The buffer will choose the representation that is closest to | |

// 'v'. If there are two at the same distance, than the number is round up. | |

// In this mode the 'requested_digits' parameter is ignored. | |

// - FIXED: produces digits necessary to print a given number with | |

// 'requested_digits' digits after the decimal point. The produced digits | |

// might be too short in which case the caller has to fill the gaps with '0's. | |

// Example: toFixed(0.001, 5) is allowed to return buffer="1", point=-2. | |

// Halfway cases are rounded up. The call toFixed(0.15, 2) thus returns | |

// buffer="2", point=0. | |

// Note: the length of the returned buffer has no meaning wrt the significance | |

// of its digits. That is, just because it contains '0's does not mean that | |

// any other digit would not satisfy the internal identity requirement. | |

// - PRECISION: produces 'requested_digits' where the first digit is not '0'. | |

// Even though the length of produced digits usually equals | |

// 'requested_digits', the function is allowed to return fewer digits, in | |

// which case the caller has to fill the missing digits with '0's. | |

// Halfway cases are again rounded up. | |

// 'BignumDtoa' expects the given buffer to be big enough to hold all digits | |

// and a terminating null-character. | |

V8_EXPORT_PRIVATE void BignumDtoa(double v, BignumDtoaMode mode, | |

int requested_digits, Vector<char> buffer, | |

int* length, int* point); | |

} // namespace internal | |

} // namespace v8 | |

#endif // V8_NUMBERS_BIGNUM_DTOA_H_ |