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// 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.
// part of "core_patch.dart";
// 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 source,
[@deprecated double onError(String source)]) {
var result = _parse(source);
if (result == null) {
if (onError == null) throw new FormatException("Invalid double", source);
return onError(source);
}
return result;
}
@patch
static double tryParse(String source) => _parse(source);
}