70da367f6b
Review URL: http://codereview.chromium.org/9231009 git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10407 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
86 lines
4.3 KiB
C++
86 lines
4.3 KiB
C++
// Copyright 2011 the V8 project authors. All rights reserved.
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following
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// disclaimer in the documentation and/or other materials provided
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// with the distribution.
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// * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived
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// from this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#ifndef V8_DTOA_H_
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#define V8_DTOA_H_
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namespace v8 {
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namespace internal {
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enum DtoaMode {
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// Return the shortest correct representation.
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// For example the output of 0.299999999999999988897 is (the less accurate but
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// correct) 0.3.
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DTOA_SHORTEST,
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// Return a fixed number of digits after the decimal point.
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// For instance fixed(0.1, 4) becomes 0.1000
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// If the input number is big, the output will be big.
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DTOA_FIXED,
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// Return a fixed number of digits, no matter what the exponent is.
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DTOA_PRECISION
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};
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// The maximal length of digits a double can have in base 10.
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// Note that DoubleToAscii null-terminates its input. So the given buffer should
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// be at least kBase10MaximalLength + 1 characters long.
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const int kBase10MaximalLength = 17;
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// Converts the given double 'v' to ASCII.
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// The result should be interpreted as buffer * 10^(point-length).
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//
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// The output depends on the given mode:
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// - SHORTEST: produce the least amount of digits for which the internal
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// identity requirement is still satisfied. If the digits are printed
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// (together with the correct exponent) then reading this number will give
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// 'v' again. The buffer will choose the representation that is closest to
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// 'v'. If there are two at the same distance, than the one farther away
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// from 0 is chosen (halfway cases - ending with 5 - are rounded up).
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// In this mode the 'requested_digits' parameter is ignored.
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// - FIXED: produces digits necessary to print a given number with
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// 'requested_digits' digits after the decimal point. The produced digits
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// might be too short in which case the caller has to fill the gaps with '0's.
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// Example: toFixed(0.001, 5) is allowed to return buffer="1", point=-2.
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// Halfway cases are rounded towards +/-Infinity (away from 0). The call
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// toFixed(0.15, 2) thus returns buffer="2", point=0.
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// The returned buffer may contain digits that would be truncated from the
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// shortest representation of the input.
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// - PRECISION: produces 'requested_digits' where the first digit is not '0'.
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// Even though the length of produced digits usually equals
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// 'requested_digits', the function is allowed to return fewer digits, in
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// which case the caller has to fill the missing digits with '0's.
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// Halfway cases are again rounded away from 0.
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// 'DoubleToAscii' expects the given buffer to be big enough to hold all digits
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// and a terminating null-character. In SHORTEST-mode it expects a buffer of
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// at least kBase10MaximalLength + 1. Otherwise, the size of the output is
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// limited to requested_digits digits plus the null terminator.
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void DoubleToAscii(double v, DtoaMode mode, int requested_digits,
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Vector<char> buffer, int* sign, int* length, int* point);
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} } // namespace v8::internal
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#endif // V8_DTOA_H_
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