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number.dart
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number.dart
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// Copyright 2016 Google Inc. Use of this source code is governed by an
// MIT-style license that can be found in the LICENSE file or at
// https://opensource.org/licenses/MIT.
import 'dart:math' as math;
import '../value.dart';
/// The maximum distance two Sass numbers are allowed to be from one another
/// before they're considered different.
final epsilon = math.pow(10, -SassNumber.precision - 1);
/// Returns whether [number1] and [number2] are equal within [epsilon].
bool fuzzyEquals(num number1, num number2) =>
(number1 - number2).abs() < epsilon;
/// `1 / epsilon`, cached since [math.pow] may not be computed at compile-time
/// and thus this probably won't be constant-folded.
final _inverseEpsilon = 1 / epsilon;
/// Returns a hash code for [number] that matches [fuzzyEquals].
int fuzzyHashCode(num number) => (number * _inverseEpsilon).round().hashCode;
/// Returns whether [number1] is less than [number2], and not [fuzzyEquals].
bool fuzzyLessThan(num number1, num number2) =>
number1 < number2 && !fuzzyEquals(number1, number2);
/// Returns whether [number1] is less than [number2], or [fuzzyEquals].
bool fuzzyLessThanOrEquals(num number1, num number2) =>
number1 < number2 || fuzzyEquals(number1, number2);
/// Returns whether [number1] is greater than [number2], and not [fuzzyEquals].
bool fuzzyGreaterThan(num number1, num number2) =>
number1 > number2 && !fuzzyEquals(number1, number2);
/// Returns whether [number1] is greater than [number2], or [fuzzyEquals].
bool fuzzyGreaterThanOrEquals(num number1, num number2) =>
number1 > number2 || fuzzyEquals(number1, number2);
/// Returns whether [number] is [fuzzyEquals] to an integer.
bool fuzzyIsInt(num number) {
// Check this before is int to work around dart-lang/sdk#43325.
if (number.isInfinite || number.isNaN) return false;
if (number is int) return true;
// Check against 0.5 rather than 0.0 so that we catch numbers that are both
// very slightly above an integer, and very slightly below.
return fuzzyEquals((number - 0.5).abs() % 1, 0.5);
}
/// If [number] is an integer according to [fuzzyIsInt], returns it as an
/// [int].
///
/// Otherwise, returns `null`.
int fuzzyAsInt(num number) => fuzzyIsInt(number) ? number.round() : null;
/// Rounds [number] to the nearest integer.
///
/// This rounds up numbers that are [fuzzyEquals] to `X.5`.
int fuzzyRound(num number) {
// If the number is within epsilon of X.5, round up (or down for negative
// numbers).
if (number > 0) {
return fuzzyLessThan(number % 1, 0.5) ? number.floor() : number.ceil();
} else {
return fuzzyLessThanOrEquals(number % 1, 0.5)
? number.floor()
: number.ceil();
}
}
/// Returns [number] if it's within [min] and [max], or `null` if it's not.
///
/// If [number] is [fuzzyEquals] to [min] or [max], it's clamped to the
/// appropriate value.
num fuzzyCheckRange(num number, num min, num max) {
if (fuzzyEquals(number, min)) return min;
if (fuzzyEquals(number, max)) return max;
if (number > min && number < max) return number;
return null;
}
/// Throws a [RangeError] if [number] isn't within [min] and [max].
///
/// If [number] is [fuzzyEquals] to [min] or [max], it's clamped to the
/// appropriate value. [name] is used in error reporting.
num fuzzyAssertRange(num number, num min, num max, [String name]) {
var result = fuzzyCheckRange(number, min, max);
if (result != null) return result;
throw RangeError.value(number, name, "must be between $min and $max.");
}