137 lines
3.5 KiB
Go
137 lines
3.5 KiB
Go
// Package math provides helper functions for doing mathematical calculations and parsing for the ecocredit module.
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package math
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import (
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"fmt"
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"github.com/cockroachdb/apd/v2"
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sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
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"github.com/cosmos/cosmos-sdk/x/group/errors"
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)
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// Dec is a wrapper struct around apd.Decimal that does no mutation of apd.Decimal's when performing
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// arithmetic, instead creating a new apd.Decimal for every operation ensuring usage is safe.
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//
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// Using apd.Decimal directly can be unsafe because apd operations mutate the underlying Decimal,
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// but when copying the big.Int structure can be shared between Decimal instances causing corruption.
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// This was originally discovered in regen0-network/mainnet#15.
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type Dec struct {
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dec apd.Decimal
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}
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func NewPositiveDecFromString(s string) (Dec, error) {
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d, err := NewDecFromString(s)
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if err != nil {
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return Dec{}, errors.ErrInvalidDecString.Wrap(err.Error())
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}
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if !d.IsPositive() {
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return Dec{}, errors.ErrInvalidDecString.Wrapf("expected a positive decimal, got %s", s)
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}
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return d, nil
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}
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func NewNonNegativeDecFromString(s string) (Dec, error) {
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d, err := NewDecFromString(s)
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if err != nil {
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return Dec{}, errors.ErrInvalidDecString.Wrap(err.Error())
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}
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if d.IsNegative() {
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return Dec{}, errors.ErrInvalidDecString.Wrapf("expected a non-negative decimal, got %s", s)
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}
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return d, nil
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}
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func (x Dec) IsPositive() bool {
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return !x.dec.Negative && !x.dec.IsZero()
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}
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func NewDecFromString(s string) (Dec, error) {
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d, _, err := apd.NewFromString(s)
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if err != nil {
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return Dec{}, errors.ErrInvalidDecString.Wrap(err.Error())
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}
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return Dec{*d}, nil
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}
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func (x Dec) String() string {
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return x.dec.Text('f')
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}
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func NewDecFromInt64(x int64) Dec {
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var res Dec
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res.dec.SetInt64(x)
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return res
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}
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// Add returns a new Dec with value `x+y` without mutating any argument and error if
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// there is an overflow.
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func (x Dec) Add(y Dec) (Dec, error) {
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var z Dec
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_, err := apd.BaseContext.Add(&z.dec, &x.dec, &y.dec)
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return z, sdkerrors.Wrap(err, "decimal addition error")
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}
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// Sub returns a new Dec with value `x-y` without mutating any argument and error if
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// there is an overflow.
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func (x Dec) Sub(y Dec) (Dec, error) {
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var z Dec
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_, err := apd.BaseContext.Sub(&z.dec, &x.dec, &y.dec)
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return z, sdkerrors.Wrap(err, "decimal subtraction error")
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}
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func (x Dec) Int64() (int64, error) {
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return x.dec.Int64()
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}
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func (x Dec) Cmp(y Dec) int {
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return x.dec.Cmp(&y.dec)
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}
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func (x Dec) IsEqual(y Dec) bool {
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return x.dec.Cmp(&y.dec) == 0
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}
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func (x Dec) IsNegative() bool {
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return x.dec.Negative && !x.dec.IsZero()
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}
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// Add adds x and y
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func Add(x Dec, y Dec) (Dec, error) {
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return x.Add(y)
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}
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var dec128Context = apd.Context{
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Precision: 34,
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MaxExponent: apd.MaxExponent,
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MinExponent: apd.MinExponent,
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Traps: apd.DefaultTraps,
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}
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// Quo returns a new Dec with value `x/y` (formatted as decimal128, 34 digit precision) without mutating any
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// argument and error if there is an overflow.
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func (x Dec) Quo(y Dec) (Dec, error) {
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var z Dec
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_, err := dec128Context.Quo(&z.dec, &x.dec, &y.dec)
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return z, sdkerrors.Wrap(err, "decimal quotient error")
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}
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func (x Dec) IsZero() bool {
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return x.dec.IsZero()
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}
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// SubNonNegative subtracts the value of y from x and returns the result with
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// arbitrary precision. Returns an error if the result is negative.
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func SubNonNegative(x Dec, y Dec) (Dec, error) {
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z, err := x.Sub(y)
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if err != nil {
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return Dec{}, err
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}
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if z.IsNegative() {
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return z, fmt.Errorf("result negative during non-negative subtraction")
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}
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return z, nil
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}
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