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Split SassNumber into separate subclasses based on units
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This allows us to use more efficient implementations in the common
case where numbers don't have complex units.

See #113
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@nex3
nex3 committed Feb 1, 2021
1 parent e664ea8 commit 3a23fb2
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4 changes: 4 additions & 0 deletions CHANGELOG.md
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@@ -1,3 +1,7 @@
## 1.32.7

* Improve the performance of unitless and single-unit numbers.

## 1.32.6

### Node JS API
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4 changes: 2 additions & 2 deletions lib/src/value/external/number.dart
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Expand Up @@ -61,8 +61,8 @@ abstract class SassNumber extends Value {

/// Creates a number with full [numeratorUnits] and [denominatorUnits].
factory SassNumber.withUnits(num value,
{Iterable<String> numeratorUnits,
Iterable<String> denominatorUnits}) = internal.SassNumber.withUnits;
{List<String> numeratorUnits,
List<String> denominatorUnits}) = internal.SassNumber.withUnits;

/// Returns [value] as an [int], if it's an integer value according to
/// [isInt].
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231 changes: 110 additions & 121 deletions lib/src/value/number.dart
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Expand Up @@ -13,6 +13,9 @@ import '../utils.dart';
import '../value.dart';
import '../visitor/interface/value.dart';
import 'external/value.dart' as ext;
import 'number/complex.dart';
import 'number/single_unit.dart';
import 'number/unitless.dart';

/// A nested map containing unit conversion rates.
///
Expand Down Expand Up @@ -157,25 +160,15 @@ final _typesByUnit = {
for (var unit in entry.value) unit: entry.key
};

// TODO(nweiz): If it's faster, add subclasses specifically for unitless numbers
// and numbers with only a single numerator unit. These should be opaque to
// users of SassNumber.

class SassNumber extends Value implements ext.SassNumber {
abstract class SassNumber extends Value implements ext.SassNumber {
static const precision = ext.SassNumber.precision;

final num value;

final List<String> numeratorUnits;

final List<String> denominatorUnits;

/// The representation of this number as two slash-separated numbers, if it
/// has one.
final Tuple2<SassNumber, SassNumber> asSlash;

bool get hasUnits => numeratorUnits.isNotEmpty || denominatorUnits.isNotEmpty;

bool get isInt => fuzzyIsInt(value);

int get asInt => fuzzyAsInt(value);
Expand All @@ -184,35 +177,42 @@ class SassNumber extends Value implements ext.SassNumber {
String get unitString =>
hasUnits ? _unitString(numeratorUnits, denominatorUnits) : '';

SassNumber(num value, [String unit])
: this.withUnits(value, numeratorUnits: unit == null ? null : [unit]);
factory SassNumber(num value, [String unit]) => unit == null
? UnitlessSassNumber(value)
: SingleUnitSassNumber(value, unit);

SassNumber.withUnits(this.value,
{Iterable<String> numeratorUnits, Iterable<String> denominatorUnits})
: numeratorUnits = numeratorUnits == null
? const []
: List.unmodifiable(numeratorUnits),
denominatorUnits = denominatorUnits == null
? const []
: List.unmodifiable(denominatorUnits),
asSlash = null;
factory SassNumber.withUnits(num value,
{List<String> numeratorUnits, List<String> denominatorUnits}) {
var emptyNumerator = numeratorUnits == null || numeratorUnits.isEmpty;
var emptyDenominator = denominatorUnits == null || denominatorUnits.isEmpty;
if (emptyNumerator && emptyDenominator) return UnitlessSassNumber(value);

if (emptyDenominator && numeratorUnits.length == 1) {
return SingleUnitSassNumber(value, numeratorUnits[0]);
} else {
return ComplexSassNumber(
value,
emptyNumerator ? const [] : List.unmodifiable(numeratorUnits),
emptyDenominator ? const [] : List.unmodifiable(denominatorUnits));
}
}

SassNumber._(this.value, this.numeratorUnits, this.denominatorUnits,
[this.asSlash]);
@protected
SassNumber.protected(this.value, this.asSlash);

T accept<T>(ValueVisitor<T> visitor) => visitor.visitNumber(this);

/// Returns a number with the same units as [this] but with [value] as its
/// value.
@protected
SassNumber withValue(num value);

/// Returns a copy of [this] without [asSlash] set.
SassNumber withoutSlash() {
if (asSlash == null) return this;
return SassNumber._(value, numeratorUnits, denominatorUnits);
}
SassNumber withoutSlash() => asSlash == null ? this : withValue(value);

/// Returns a copy of [this] with [this.asSlash] set to a tuple containing
/// [numerator] and [denominator].
SassNumber withSlash(SassNumber numerator, SassNumber denominator) =>
SassNumber._(value, numeratorUnits, denominatorUnits,
Tuple2(numerator, denominator));
SassNumber withSlash(SassNumber numerator, SassNumber denominator);

SassNumber assertNumber([String name]) => this;

Expand All @@ -239,7 +239,7 @@ class SassNumber extends Value implements ext.SassNumber {
if (denominatorUnits.isNotEmpty) return false;
if (numeratorUnits.isEmpty) return true;
return numeratorUnits.length == 1 &&
_conversionFactor(numeratorUnits.first, unit) != null;
conversionFactor(numeratorUnits.first, unit) != null;
}

void assertUnit(String unit, [String name]) {
Expand Down Expand Up @@ -363,7 +363,7 @@ class SassNumber extends Value implements ext.SassNumber {
var oldNumerators = numeratorUnits.toList();
for (var newNumerator in newNumerators) {
removeFirstWhere<String>(oldNumerators, (oldNumerator) {
var factor = _conversionFactor(newNumerator, oldNumerator);
var factor = conversionFactor(newNumerator, oldNumerator);
if (factor == null) return false;
value *= factor;
return true;
Expand All @@ -373,7 +373,7 @@ class SassNumber extends Value implements ext.SassNumber {
var oldDenominators = denominatorUnits.toList();
for (var newDenominator in newDenominators) {
removeFirstWhere<String>(oldDenominators, (oldDenominator) {
var factor = _conversionFactor(newDenominator, oldDenominator);
var factor = conversionFactor(newDenominator, oldDenominator);
if (factor == null) return false;
value /= factor;
return true;
Expand Down Expand Up @@ -431,129 +431,112 @@ class SassNumber extends Value implements ext.SassNumber {

Value modulo(Value other) {
if (other is SassNumber) {
return _coerceNumber(other, (num1, num2) {
if (num2 > 0) return num1 % num2;
if (num2 == 0) return double.nan;

// Dart has different mod-negative semantics than Ruby, and thus than
// Sass.
var result = num1 % num2;
return result == 0 ? 0 : result + num2;
});
return withValue(_coerceUnits(other, moduloLikeSass));
}
throw SassScriptException('Undefined operation "$this % $other".');
}

/// Return [num1] modulo [num2], using Sass's modulo semantics, which it
/// inherited from Ruby and which differ from Dart's.
num moduloLikeSass(num num1, num num2) {
if (num2 > 0) return num1 % num2;
if (num2 == 0) return double.nan;

// Dart has different mod-negative semantics than Ruby, and thus than
// Sass.
var result = num1 % num2;
return result == 0 ? 0 : result + num2;
}

Value plus(Value other) {
if (other is SassNumber) {
return _coerceNumber(other, (num1, num2) => num1 + num2);
return withValue(_coerceUnits(other, (num1, num2) => num1 + num2));
}
if (other is! SassColor) return super.plus(other);
throw SassScriptException('Undefined operation "$this + $other".');
}

Value minus(Value other) {
if (other is SassNumber) {
return _coerceNumber(other, (num1, num2) => num1 - num2);
return withValue(_coerceUnits(other, (num1, num2) => num1 - num2));
}
if (other is! SassColor) return super.minus(other);
throw SassScriptException('Undefined operation "$this - $other".');
}

Value times(Value other) {
if (other is SassNumber) {
return _multiplyUnits(value * other.value, numeratorUnits,
denominatorUnits, other.numeratorUnits, other.denominatorUnits);
if (!other.hasUnits) return withValue(value * other.value);
return multiplyUnits(
value * other.value, other.numeratorUnits, other.denominatorUnits);
}
throw SassScriptException('Undefined operation "$this * $other".');
}

Value dividedBy(Value other) {
if (other is SassNumber) {
return _multiplyUnits(value / other.value, numeratorUnits,
denominatorUnits, other.denominatorUnits, other.numeratorUnits);
if (!other.hasUnits) return withValue(value / other.value);
return multiplyUnits(
value / other.value, other.denominatorUnits, other.numeratorUnits);
}
return super.dividedBy(other);
}

Value unaryPlus() => this;

Value unaryMinus() => SassNumber.withUnits(-value,
numeratorUnits: numeratorUnits, denominatorUnits: denominatorUnits);

/// Converts [other]'s value to be compatible with this number's, calls
/// [operation] with the resulting numbers, and wraps the result in a
/// [SassNumber].
///
/// Throws a [SassScriptException] if the two numbers' units are incompatible.
SassNumber _coerceNumber(
SassNumber other, num operation(num num1, num num2)) {
var result = _coerceUnits(other, operation);
return SassNumber.withUnits(result,
numeratorUnits: hasUnits ? numeratorUnits : other.numeratorUnits,
denominatorUnits: hasUnits ? denominatorUnits : other.denominatorUnits);
}

/// Converts [other]'s value to be compatible with this number's, and calls
/// [operation] with the resulting numbers.
///
/// Throws a [SassScriptException] if the two numbers' units are incompatible.
@protected
T _coerceUnits<T>(SassNumber other, T operation(num num1, num num2)) {
num num1;
num num2;
if (hasUnits) {
num1 = value;
try {
num2 = other.coerceValueToMatch(this);
} on SassScriptException {
// If the conversion fails, re-run it in the other direction. This will
// generate an error message that prints [this] before [other], which is
// more readable.
coerceValueToMatch(other);
rethrow; // This should be unreachable.
}
} else {
num1 = coerceValueToMatch(other);
num2 = other.value;
try {
return operation(value, other.coerceValueToMatch(this));
} on SassScriptException {
// If the conversion fails, re-run it in the other direction. This will
// generate an error message that prints [this] before [other], which is
// more readable.
coerceValueToMatch(other);
rethrow; // This should be unreachable.
}

return operation(num1, num2);
}

/// Returns a new number that's equivalent to `value numerators1/denominators1
/// * 1 numerators2/denominators2`.
SassNumber _multiplyUnits(
num value,
List<String> numerators1,
List<String> denominators1,
List<String> numerators2,
List<String> denominators2) {
/// Returns a new number that's equivalent to `value
/// this.numeratorUnits/this.denominatorUnits * 1
/// otherNumerators/otherDenominators`.
@protected
SassNumber multiplyUnits(
num value, List<String> otherNumerators, List<String> otherDenominators) {
// Short-circuit without allocating any new unit lists if possible.
if (numerators1.isEmpty) {
if (denominators2.isEmpty &&
!_areAnyConvertible(denominators1, numerators2)) {
if (numeratorUnits.isEmpty) {
if (otherDenominators.isEmpty &&
!_areAnyConvertible(denominatorUnits, otherNumerators)) {
return SassNumber.withUnits(value,
numeratorUnits: numerators2, denominatorUnits: denominators1);
} else if (denominators1.isEmpty) {
numeratorUnits: otherNumerators,
denominatorUnits: denominatorUnits);
} else if (denominatorUnits.isEmpty) {
return SassNumber.withUnits(value,
numeratorUnits: numerators2, denominatorUnits: denominators2);
numeratorUnits: otherNumerators,
denominatorUnits: otherDenominators);
}
} else if (numerators2.isEmpty) {
if (denominators2.isEmpty) {
} else if (otherNumerators.isEmpty) {
if (otherDenominators.isEmpty) {
return SassNumber.withUnits(value,
numeratorUnits: numerators1, denominatorUnits: denominators2);
} else if (denominators1.isEmpty &&
!_areAnyConvertible(numerators1, denominators2)) {
numeratorUnits: numeratorUnits,
denominatorUnits: otherDenominators);
} else if (denominatorUnits.isEmpty &&
!_areAnyConvertible(numeratorUnits, otherDenominators)) {
return SassNumber.withUnits(value,
numeratorUnits: numerators1, denominatorUnits: denominators2);
numeratorUnits: numeratorUnits,
denominatorUnits: otherDenominators);
}
}

var newNumerators = <String>[];
var mutableDenominators2 = denominators2.toList();
for (var numerator in numerators1) {
removeFirstWhere<String>(mutableDenominators2, (denominator) {
var factor = _conversionFactor(numerator, denominator);
var mutableOtherDenominators = otherDenominators.toList();
for (var numerator in numeratorUnits) {
removeFirstWhere<String>(mutableOtherDenominators, (denominator) {
var factor = conversionFactor(numerator, denominator);
if (factor == null) return false;
value /= factor;
return true;
Expand All @@ -563,10 +546,10 @@ class SassNumber extends Value implements ext.SassNumber {
});
}

var mutableDenominators1 = denominators1.toList();
for (var numerator in numerators2) {
removeFirstWhere<String>(mutableDenominators1, (denominator) {
var factor = _conversionFactor(numerator, denominator);
var mutableDenominatorUnits = denominatorUnits.toList();
for (var numerator in otherNumerators) {
removeFirstWhere<String>(mutableDenominatorUnits, (denominator) {
var factor = conversionFactor(numerator, denominator);
if (factor == null) return false;
value /= factor;
return true;
Expand All @@ -578,7 +561,8 @@ class SassNumber extends Value implements ext.SassNumber {

return SassNumber.withUnits(value,
numeratorUnits: newNumerators,
denominatorUnits: mutableDenominators1..addAll(mutableDenominators2));
denominatorUnits: mutableDenominatorUnits
..addAll(mutableOtherDenominators));
}

/// Returns whether there exists a unit in [units1] that can be converted to a
Expand All @@ -596,8 +580,9 @@ class SassNumber extends Value implements ext.SassNumber {

/// Returns the number of [unit1]s per [unit2].
///
/// Equivalently, `1unit1 * _conversionFactor(unit1, unit2) = 1unit2`.
num _conversionFactor(String unit1, String unit2) {
/// Equivalently, `1unit1 * conversionFactor(unit1, unit2) = 1unit2`.
@protected
num conversionFactor(String unit1, String unit2) {
if (unit1 == unit2) return 1;
var innerMap = _conversions[unit1];
if (innerMap == null) return null;
Expand Down Expand Up @@ -670,13 +655,17 @@ class SassNumber extends Value implements ext.SassNumber {
///
/// That is, if `X units1 == Y units2`, `X * _canonicalMultiplier(units1) == Y
/// * _canonicalMultiplier(units2)`.
num _canonicalMultiplier(List<String> units) =>
units.fold(1, (multiplier, unit) {
var innerMap = _conversions[unit];
return innerMap == null
? multiplier
: multiplier / innerMap.values.first;
});
num _canonicalMultiplier(List<String> units) => units.fold(
1, (multiplier, unit) => multiplier * canonicalMultiplierForUnit(unit));

/// Returns a multiplier that encapsulates unit equivalence with [unit].
///
/// That is, if `X unit1 == Y unit2`, `X * canonicalMultiplierForUnit(unit1)
/// == Y * canonicalMultiplierForUnit(unit2)`.
num canonicalMultiplierForUnit(String unit) {
var innerMap = _conversions[unit];
return innerMap == null ? 1 : 1 / innerMap.values.first;
}

/// Throws a [SassScriptException] with the given [message].
SassScriptException _exception(String message, [String name]) =>
Expand Down
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