| // Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file |
| // for details. All rights reserved. Use of this source code is governed by a |
| // BSD-style license that can be found in the LICENSE file. |
| // Dart core library. |
| |
| // VM implementation of double. |
| |
| patch class double { |
| |
| static double _nativeParse(String str, |
| int start, int end) native "Double_parse"; |
| |
| static double _tryParseDouble(var str, var start, var end) { |
| assert(start < end); |
| const int _DOT = 0x2e; // '.' |
| const int _ZERO = 0x30; // '0' |
| const int _MINUS = 0x2d; // '-' |
| const int _N = 0x4e; // 'N' |
| const int _a = 0x61; // 'a' |
| const int _I = 0x49; // 'I' |
| const int _e = 0x65; // 'e' |
| int exponent = 0; |
| // Set to non-zero if a digit is seen. Avoids accepting ".". |
| bool digitsSeen = false; |
| // Added to exponent for each digit. Set to -1 when seeing '.'. |
| int exponentDelta = 0; |
| double doubleValue = 0.0; |
| double sign = 1.0; |
| int firstChar = str.codeUnitAt(start); |
| if (firstChar == _MINUS) { |
| sign = -1.0; |
| start++; |
| if (start == end) return null; |
| firstChar = str.codeUnitAt(start); |
| } |
| if (firstChar == _I) { |
| if (end == start + 8 && str.startsWith("nfinity", start + 1)) { |
| return sign * double.INFINITY; |
| } |
| return null; |
| } |
| if (firstChar == _N) { |
| if (end == start + 3 && |
| str.codeUnitAt(start + 1) == _a && |
| str.codeUnitAt(start + 2) == _N) { |
| return double.NAN; |
| } |
| return null; |
| } |
| |
| int firstDigit = firstChar ^ _ZERO; |
| if (firstDigit <= 9) { |
| start++; |
| doubleValue = firstDigit.toDouble(); |
| digitsSeen = true; |
| } |
| for (int i = start; i < end; i++) { |
| int c = str.codeUnitAt(i); |
| int digit = c ^ _ZERO; // '0'-'9' characters are now 0-9 integers. |
| if (digit <= 9) { |
| doubleValue = 10.0 * doubleValue + digit; |
| // Doubles at or above this value (2**53) might have lost precission. |
| const double MAX_EXACT_DOUBLE = 9007199254740992.0; |
| if (doubleValue >= MAX_EXACT_DOUBLE) return null; |
| exponent += exponentDelta; |
| digitsSeen = true; |
| } else if (c == _DOT && exponentDelta == 0) { |
| exponentDelta = -1; |
| } else if ((c | 0x20) == _e) { |
| i++; |
| if (i == end) return null; |
| // int._tryParseSmi treats its end argument as inclusive. |
| int expPart = int._tryParseSmi(str, i, end - 1); |
| if (expPart == null) return null; |
| exponent += expPart; |
| break; |
| } else { |
| return null; |
| } |
| } |
| if (!digitsSeen) return null; // No digits. |
| if (exponent == 0) return sign * doubleValue; |
| const P10 = POWERS_OF_TEN; // From shared library |
| if (exponent < 0) { |
| int negExponent = -exponent; |
| if (negExponent >= P10.length) return null; |
| return sign * (doubleValue / P10[negExponent]); |
| } |
| if (exponent >= P10.length) return null; |
| return sign * (doubleValue * P10[exponent]); |
| } |
| |
| static double _parse(var str) { |
| int len = str.length; |
| int start = str._firstNonWhitespace(); |
| if (start == len) return null; // All whitespace. |
| int end = str._lastNonWhitespace() + 1; |
| assert(start < end); |
| var result = _tryParseDouble(str, start, end); |
| if (result != null) return result; |
| return _nativeParse(str, start, end); |
| } |
| |
| /* patch */ static double parse(String str, |
| [double onError(String str)]) { |
| var result = _parse(str); |
| if (result == null) { |
| if (onError == null) throw new FormatException("Invalid double", str); |
| return onError(str); |
| } |
| return result; |
| } |
| } |