stack_wallet/lib/utilities/amount/amount.dart

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import 'dart:convert';
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import 'package:decimal/decimal.dart';
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import 'package:intl/number_symbols.dart';
import 'package:intl/number_symbols_data.dart';
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class Amount {
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Amount({
required BigInt rawValue,
required this.fractionDigits,
}) : assert(fractionDigits >= 0),
_value = rawValue;
/// special zero case with [fractionDigits] set to 0
static Amount get zero => Amount(
rawValue: BigInt.zero,
fractionDigits: 0,
);
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/// truncate decimal value to [fractionDigits] places
Amount.fromDecimal(Decimal amount, {required this.fractionDigits})
: assert(fractionDigits >= 0),
_value = amount.shift(fractionDigits).toBigInt();
// ===========================================================================
// ======= Instance properties ===============================================
final int fractionDigits;
final BigInt _value;
// ===========================================================================
// ======= Getters ===========================================================
/// raw base value
BigInt get raw => _value;
/// actual decimal vale represented
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Decimal get decimal => Decimal.fromBigInt(raw).shift(-1 * fractionDigits);
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/// convenience getter
@Deprecated("provided for convenience only. Use fractionDigits instead.")
int get decimals => fractionDigits;
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// ===========================================================================
// ======= Serialization =====================================================
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Map<String, dynamic> toMap() {
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return {"raw": raw.toString(), "fractionDigits": fractionDigits};
}
String toJsonString() {
return jsonEncode(toMap());
}
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String localizedStringAsFixed({
required String locale,
int? decimalPlaces,
}) {
decimalPlaces ??= fractionDigits;
assert(decimalPlaces >= 0);
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final wholeNumber = decimal.truncate();
if (decimalPlaces == 0) {
return wholeNumber.toStringAsFixed(0);
}
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final String separator =
(numberFormatSymbols[locale] as NumberSymbols?)?.DECIMAL_SEP ??
(numberFormatSymbols[locale.substring(0, 2)] as NumberSymbols?)
?.DECIMAL_SEP ??
".";
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final fraction = decimal - wholeNumber;
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return "${wholeNumber.toStringAsFixed(0)}$separator${fraction.toStringAsFixed(decimalPlaces).substring(2)}";
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}
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// ===========================================================================
// ======= Deserialization ===================================================
static Amount fromSerializedJsonString(String json) {
final map = jsonDecode(json) as Map;
return Amount(
rawValue: BigInt.parse(map["raw"] as String),
fractionDigits: map["fractionDigits"] as int,
);
}
// ===========================================================================
// ======= operators =========================================================
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bool operator >(Amount other) => decimal > other.decimal;
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bool operator <(Amount other) => decimal < other.decimal;
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bool operator >=(Amount other) => decimal >= other.decimal;
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bool operator <=(Amount other) => decimal <= other.decimal;
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Amount operator +(Amount other) {
if (fractionDigits != other.fractionDigits) {
throw ArgumentError(
"fractionDigits do not match: this=$this, other=$other");
}
return Amount(
rawValue: raw + other.raw,
fractionDigits: fractionDigits,
);
}
Amount operator -(Amount other) {
if (fractionDigits != other.fractionDigits) {
throw ArgumentError(
"fractionDigits do not match: this=$this, other=$other");
}
return Amount(
rawValue: raw - other.raw,
fractionDigits: fractionDigits,
);
}
Amount operator *(Amount other) {
if (fractionDigits != other.fractionDigits) {
throw ArgumentError(
"fractionDigits do not match: this=$this, other=$other");
}
return Amount(
rawValue: raw * other.raw,
fractionDigits: fractionDigits,
);
}
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// ===========================================================================
// ======= Overrides =========================================================
@override
String toString() => "Amount($raw, $fractionDigits)";
@override
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bool operator ==(Object other) =>
identical(this, other) ||
other is Amount &&
runtimeType == other.runtimeType &&
raw == other.raw &&
fractionDigits == other.fractionDigits;
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@override
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int get hashCode => Object.hashAll([raw, fractionDigits]);
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}
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// =============================================================================
// =============================================================================
// ======= Extensions ==========================================================
extension DecimalAmountExt on Decimal {
Amount toAmount({required int fractionDigits}) {
return Amount.fromDecimal(
this,
fractionDigits: fractionDigits,
);
}
}
extension IntAmountExtension on int {
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Amount toAmountAsRaw({required int fractionDigits}) {
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return Amount(
rawValue: BigInt.from(this),
fractionDigits: fractionDigits,
);
}
}