Merge branch 'shopspring:master' into master

CHANGELOG.md

@@ -1,3 +1,11 @@
+## Decimal v1.3.1
+
+#### ENHANCEMENTS
+- Reduce memory allocation in case of initialization from big.Int [#252](https://github.com/shopspring/decimal/pull/252)
+
+#### BUGFIXES
+- Fix binary marshalling of decimal zero value  [#253](https://github.com/shopspring/decimal/pull/253)
+
 ## Decimal v1.3.0
 
 #### FEATURES

decimal.go

@@ -120,7 +120,7 @@ func NewFromInt32(value int32) Decimal {
 // NewFromBigInt returns a new Decimal from a big.Int, value * 10 ^ exp
 func NewFromBigInt(value *big.Int, exp int32) Decimal {
 	return Decimal{
-		value: big.NewInt(0).Set(value),
+		value: new(big.Int).Set(value),
 		exp:   exp,
 	}
 }
@@ -552,7 +552,7 @@ func (d Decimal) Div(d2 Decimal) Decimal {
 	return d.DivRound(d2, int32(DivisionPrecision))
 }
 
-// QuoRem does divsion with remainder
+// QuoRem does division with remainder
 // d.QuoRem(d2,precision) returns quotient q and remainder r such that
 //   d = d2 * q + r, q an integer multiple of 10^(-precision)
 //   0 <= r < abs(d2) * 10 ^(-precision) if d>=0
@@ -628,7 +628,7 @@ func (d Decimal) DivRound(d2 Decimal, precision int32) Decimal {
 
 // Mod returns d % d2.
 func (d Decimal) Mod(d2 Decimal) Decimal {
-	quo := d.Div(d2).Truncate(0)
+	quo := d.DivRound(d2, -d.exp+1).Truncate(0)
 	return d.Sub(d2.Mul(quo))
 }
 
@@ -831,7 +831,7 @@ func (d Decimal) IsInteger() bool {
 	// When the exponent is negative we have to check every number after the decimal place
 	// If all of them are zeroes, we are sure that given decimal can be represented as an integer
 	var r big.Int
-	q := big.NewInt(0).Set(d.value)
+	q := new(big.Int).Set(d.value)
 	for z := abs(d.exp); z > 0; z-- {
 		q.QuoRem(q, tenInt, &r)
 		if r.Cmp(zeroInt) != 0 {
@@ -949,7 +949,7 @@ func (d Decimal) Exponent() int32 {
 func (d Decimal) Coefficient() *big.Int {
 	d.ensureInitialized()
 	// we copy the coefficient so that mutating the result does not mutate the Decimal.
-	return big.NewInt(0).Set(d.value)
+	return new(big.Int).Set(d.value)
 }
 
 // CoefficientInt64 returns the coefficient of the decimal as int64. It is scaled by 10^Exponent()
@@ -1353,10 +1353,10 @@ func (d Decimal) MarshalJSON() ([]byte, error) {
 // UnmarshalBinary implements the encoding.BinaryUnmarshaler interface. As a string representation
 // is already used when encoding to text, this method stores that string as []byte
 func (d *Decimal) UnmarshalBinary(data []byte) error {
-	// Verify we have at least 5 bytes, 4 for the exponent and at least 1 more
-	// for the GOB encoded value.
-	if len(data) < 5 {
-		return fmt.Errorf("error decoding binary %v: expected at least 5 bytes, got %d", data, len(data))
+	// Verify we have at least 4 bytes for the exponent. The GOB encoded value
+	// may be empty.
+	if len(data) < 4 {
+		return fmt.Errorf("error decoding binary %v: expected at least 4 bytes, got %d", data, len(data))
 	}
 
 	// Extract the exponent

decimal_test.go

@@ -2134,8 +2134,12 @@ func TestDecimal_Mod(t *testing.T) {
 	inputs := map[Inp]string{
 		Inp{"3", "2"}:                           "1",
 		Inp{"3451204593", "2454495034"}:         "996709559",
-		Inp{"24544.95034", ".3451204593"}: "0.3283950433",
-		Inp{".1", ".1"}:                   "0",
+		Inp{"9999999999", "1275"}:               "324",
+		Inp{"9999999999.9999998", "1275.49"}:    "239.2399998",
+		Inp{"24544.95034", "0.3451204593"}:      "0.3283950433",
+		Inp{"0.499999999999999999", "0.25"}:     "0.249999999999999999",
+		Inp{"0.989512958912895912", "0.000001"}: "0.000000958912895912",
+		Inp{"0.1", "0.1"}:                       "0",
 		Inp{"0", "1.001"}:                       "0",
 		Inp{"-7.5", "2"}:                        "-1.5",
 		Inp{"7.5", "-2"}:                        "1.5",
@@ -3003,6 +3007,25 @@ func TestBinary(t *testing.T) {
 	}
 }
 
+func TestBinary_Zero(t *testing.T) {
+	var d1 Decimal
+
+	b, err := d1.MarshalBinary()
+	if err != nil {
+		t.Fatalf("error marshalling %v to binary: %v", d1, err)
+	}
+
+	var d2 Decimal
+	err = (&d2).UnmarshalBinary(b)
+	if err != nil {
+		t.Errorf("error unmarshalling from binary: %v", err)
+	}
+
+	if !d1.Equals(d2) {
+		t.Errorf("expected %v when restoring, got %v", d1, d2)
+	}
+}
+
 func TestBinary_DataTooShort(t *testing.T) {
 	var d Decimal