Merge 86c2d2acf2 into a1bdfc355e

* Drop support for Go versions older than 1.10
* Remove 1.18 from test suite

.github/workflows/ci.yml

@@ -1,11 +1,15 @@
 name: ci
-on: [push]
+on:
+  push:
+    branches:
+      - master
+  pull_request:
 jobs:
   ci-job:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        go: [ '1.7.x', '1.18', '1.19', '1.20', '1.21', '1.x' ]
+        go: [ '1.10.x', '1.19', '1.20', '1.21', '1.22', '1.x' ]
     name: Go ${{ matrix.go }}
     steps:
       - uses: actions/checkout@v4

CHANGELOG.md

@@ -1,3 +1,30 @@
+## Decimal v1.4.0
+#### BREAKING
+- Drop support for Go version older than 1.10 [#361](https://github.com/shopspring/decimal/pull/361)
+
+#### FEATURES
+- Add implementation of natural logarithm [#339](https://github.com/shopspring/decimal/pull/339) [#357](https://github.com/shopspring/decimal/pull/357)
+- Add improved implementation of power operation [#358](https://github.com/shopspring/decimal/pull/358)
+- Add Compare method which forwards calls to Cmp [#346](https://github.com/shopspring/decimal/pull/346)
+- Add NewFromBigRat constructor [#288](https://github.com/shopspring/decimal/pull/288)
+- Add NewFromUint64 constructor [#352](https://github.com/shopspring/decimal/pull/352)
+
+#### ENHANCEMENTS
+- Migrate to Github Actions [#245](https://github.com/shopspring/decimal/pull/245) [#340](https://github.com/shopspring/decimal/pull/340)
+- Fix examples for RoundDown, RoundFloor, RoundUp, and RoundCeil [#285](https://github.com/shopspring/decimal/pull/285) [#328](https://github.com/shopspring/decimal/pull/328) [#341](https://github.com/shopspring/decimal/pull/341)
+- Use Godoc standard to mark deprecated Equals and StringScaled methods [#342](https://github.com/shopspring/decimal/pull/342)
+- Removed unnecessary min function for RescalePair method [#265](https://github.com/shopspring/decimal/pull/265)
+- Avoid reallocation of initial slice in MarshalBinary (GobEncode) [#355](https://github.com/shopspring/decimal/pull/355)
+- Optimize NumDigits method [#301](https://github.com/shopspring/decimal/pull/301) [#356](https://github.com/shopspring/decimal/pull/356)
+- Optimize BigInt method [#359](https://github.com/shopspring/decimal/pull/359)
+- Support scanning uint64 [#131](https://github.com/shopspring/decimal/pull/131) [#364](https://github.com/shopspring/decimal/pull/364)
+- Add docs section with alternative libraries [#363](https://github.com/shopspring/decimal/pull/363)
+
+#### BUGFIXES
+- Fix incorrect calculation of decimal modulo [#258](https://github.com/shopspring/decimal/pull/258) [#317](https://github.com/shopspring/decimal/pull/317)
+- Allocate new(big.Int) in Copy method to deeply clone it [#278](https://github.com/shopspring/decimal/pull/278)
+- Fix overflow edge case in QuoRem method [#322](https://github.com/shopspring/decimal/pull/322)
+
 ## Decimal v1.3.1
 
 #### ENHANCEMENTS

README.md

@@ -22,7 +22,12 @@ Run `go get github.com/shopspring/decimal`
 
 ## Requirements 
 
-Decimal library requires Go version `>=1.7`
+Decimal library requires Go version `>=1.10`
+
+## Documentation
+
+http://godoc.org/github.com/shopspring/decimal
+
 
 ## Usage
 
@@ -59,14 +64,16 @@ func main() {
 }
 ```
 
-## Documentation
+## Alternative libraries
 
-http://godoc.org/github.com/shopspring/decimal
+When working with decimal numbers, you might face problems this library is not perfectly suited for. 
+Fortunately, thanks to the wonderful community we have a dozen other libraries that you can choose from.  
+Explore other alternatives to find the one that best fits your needs :)  
 
-## Production Usage
-
-* [Spring](https://shopspring.com/), since August 14, 2014.
-* If you are using this in production, please let us know!
+* [cockroachdb/apd](https://github.com/cockroachdb/apd) - arbitrary precision, mutable and rich API similar to `big.Int`, more performant than this library 
+* [alpacahq/alpacadecimal](https://github.com/alpacahq/alpacadecimal) - high performance, low precision (12 digits), fully compatible API with this library 
+* [govalues/decimal](https://github.com/govalues/decimal) - high performance, zero-allocation, low precision (19 digits)
+* [greatcloak/decimal](https://github.com/greatcloak/decimal) - fork focusing on billing and e-commerce web application related use cases, includes out-of-the-box BSON marshaling support
 
 ## FAQ
 

decimal.go

@@ -130,6 +130,18 @@ func NewFromInt32(value int32) Decimal {
 	}
 }
 
+// NewFromUint64 converts an uint64 to Decimal.
+//
+// Example:
+//
+//	NewFromUint64(123).String() // output: "123"
+func NewFromUint64(value uint64) Decimal {
+	return Decimal{
+		value: new(big.Int).SetUint64(value),
+		exp:   0,
+	}
+}
+
 // NewFromBigInt returns a new Decimal from a big.Int, value * 10 ^ exp
 func NewFromBigInt(value *big.Int, exp int32) Decimal {
 	return Decimal{
@@ -1224,14 +1236,33 @@ func (d Decimal) Ln(precision int32) (Decimal, error) {
 }
 
 // NumDigits returns the number of digits of the decimal coefficient (d.Value)
-// Note: Current implementation is extremely slow for large decimals and/or decimals with large fractional part
 func (d Decimal) NumDigits() int {
-	d.ensureInitialized()
-	// Note(mwoss): It can be optimized, unnecessary cast of big.Int to string
-	if d.IsNegative() {
-		return len(d.value.String()) - 1
+	if d.value == nil {
+		return 1
 	}
-	return len(d.value.String())
+
+	if d.value.IsInt64() {
+		i64 := d.value.Int64()
+		// restrict fast path to integers with exact conversion to float64
+		if i64 <= (1<<53) && i64 >= -(1<<53) {
+			if i64 == 0 {
+				return 1
+			}
+			return int(math.Log10(math.Abs(float64(i64)))) + 1
+		}
+	}
+
+	estimatedNumDigits := int(float64(d.value.BitLen()) / math.Log2(10))
+
+	// estimatedNumDigits (lg10) may be off by 1, need to verify
+	digitsBigInt := big.NewInt(int64(estimatedNumDigits))
+	errorCorrectionUnit := digitsBigInt.Exp(tenInt, digitsBigInt, nil)
+
+	if d.value.CmpAbs(errorCorrectionUnit) >= 0 {
+		return estimatedNumDigits + 1
+	}
+
+	return estimatedNumDigits
 }
 
 // IsInteger returns true when decimal can be represented as an integer value, otherwise, it returns false.
@@ -1387,9 +1418,7 @@ func (d Decimal) IntPart() int64 {
 // BigInt returns integer component of the decimal as a BigInt.
 func (d Decimal) BigInt() *big.Int {
 	scaledD := d.rescale(0)
-	i := &big.Int{}
-	i.SetString(scaledD.String(), 10)
-	return i
+	return scaledD.value
 }
 
 // BigFloat returns decimal as BigFloat.
@@ -1818,6 +1847,11 @@ func (d *Decimal) Scan(value interface{}) error {
 		*d = New(v, 0)
 		return nil
 
+	case uint64:
+		// while clickhouse may send 0 in db as uint64
+		*d = NewFromUint64(v)
+		return nil
+
 	default:
 		// default is trying to interpret value stored as string
 		str, err := unquoteIfQuoted(v)

decimal_bench_test.go

@@ -121,6 +121,34 @@ func BenchmarkDecimal_RoundCash_Five(b *testing.B) {
 	}
 }
 
+func numDigits(b *testing.B, want int, val Decimal) {
+	b.Helper()
+	for i := 0; i < b.N; i++ {
+		if have := val.NumDigits(); have != want {
+			b.Fatalf("\nHave: %d\nWant: %d", have, want)
+		}
+	}
+}
+
+func BenchmarkDecimal_NumDigits10(b *testing.B) {
+	numDigits(b, 10, New(3478512345, -3))
+}
+
+func BenchmarkDecimal_NumDigits100(b *testing.B) {
+	s := make([]byte, 102)
+	for i := range s {
+		s[i] = byte('0' + i%10)
+	}
+	s[0] = '-'
+	s[100] = '.'
+	d, err := NewFromString(string(s))
+	if err != nil {
+		b.Log(d)
+		b.Error(err)
+	}
+	numDigits(b, 100, d)
+}
+
 func Benchmark_Cmp(b *testing.B) {
 	decimals := DecimalSlice([]Decimal{})
 	for i := 0; i < 1000000; i++ {
@@ -132,7 +160,7 @@ func Benchmark_Cmp(b *testing.B) {
 	}
 }
 
-func Benchmark_decimal_Decimal_Add_different_precision(b *testing.B) {
+func BenchmarkDecimal_Add_different_precision(b *testing.B) {
 	d1 := NewFromFloat(1000.123)
 	d2 := NewFromFloat(500).Mul(NewFromFloat(0.12))
 
@@ -143,7 +171,7 @@ func Benchmark_decimal_Decimal_Add_different_precision(b *testing.B) {
 	}
 }
 
-func Benchmark_decimal_Decimal_Sub_different_precision(b *testing.B) {
+func BenchmarkDecimal_Sub_different_precision(b *testing.B) {
 	d1 := NewFromFloat(1000.123)
 	d2 := NewFromFloat(500).Mul(NewFromFloat(0.12))
 
@@ -154,7 +182,7 @@ func Benchmark_decimal_Decimal_Sub_different_precision(b *testing.B) {
 	}
 }
 
-func Benchmark_decimal_Decimal_Add_same_precision(b *testing.B) {
+func BenchmarkDecimal_Add_same_precision(b *testing.B) {
 	d1 := NewFromFloat(1000.123)
 	d2 := NewFromFloat(500.123)
 
@@ -165,7 +193,7 @@ func Benchmark_decimal_Decimal_Add_same_precision(b *testing.B) {
 	}
 }
 
-func Benchmark_decimal_Decimal_Sub_same_precision(b *testing.B) {
+func BenchmarkDecimal_Sub_same_precision(b *testing.B) {
 	d1 := NewFromFloat(1000.123)
 	d2 := NewFromFloat(500.123)
 

decimal_test.go

@@ -481,6 +481,7 @@ func TestNewFromInt(t *testing.T) {
 		1:                    "1",
 		323412345:            "323412345",
 		9223372036854775807:  "9223372036854775807",
+		-9223372036854775808: "-9223372036854775808",
 	}
 
 	// add negatives
@@ -506,6 +507,7 @@ func TestNewFromInt32(t *testing.T) {
 		1:           "1",
 		323412345:   "323412345",
 		2147483647:  "2147483647",
+		-2147483648: "-2147483648",
 	}
 
 	// add negatives
@@ -525,6 +527,25 @@ func TestNewFromInt32(t *testing.T) {
 	}
 }
 
+func TestNewFromUint64(t *testing.T) {
+	tests := map[uint64]string{
+		0:                    "0",
+		1:                    "1",
+		323412345:            "323412345",
+		9223372036854775807:  "9223372036854775807",
+		18446744073709551615: "18446744073709551615",
+	}
+
+	for input, s := range tests {
+		d := NewFromUint64(input)
+		if d.String() != s {
+			t.Errorf("expected %s, got %s (%s, %d)",
+				s, d.String(),
+				d.value.String(), d.exp)
+		}
+	}
+}
+
 func TestNewFromBigIntWithExponent(t *testing.T) {
 	type Inp struct {
 		val *big.Int
@@ -2396,104 +2417,57 @@ func TestDecimal_Max(t *testing.T) {
 	}
 }
 
-func TestDecimal_Scan(t *testing.T) {
-	// test the Scan method that implements the
-	// sql.Scanner interface
-	// check for the for different type of values
-	// that are possible to be received from the database
-	// drivers
+func scanHelper(t *testing.T, dbval interface{}, expected Decimal) {
+	t.Helper()
 
-	// in normal operations the db driver (sqlite at least)
-	// will return an int64 if you specified a numeric format
 	a := Decimal{}
-	dbvalue := 54.33
-	expected := NewFromFloat(dbvalue)
-
-	err := a.Scan(dbvalue)
-	if err != nil {
+	if err := a.Scan(dbval); err != nil {
 		// Scan failed... no need to test result value
-		t.Errorf("a.Scan(54.33) failed with message: %s", err)
-
-	} else {
+		t.Errorf("a.Scan(%v) failed with message: %s", dbval, err)
+	} else if !a.Equal(expected) {
 		// Scan succeeded... test resulting values
-		if !a.Equal(expected) {
 		t.Errorf("%s does not equal to %s", a, expected)
 	}
 }
 
+func TestDecimal_Scan(t *testing.T) {
+	// test the Scan method that implements the sql.Scanner interface
+	// check different types received from various database drivers
+
+	dbvalue := 54.33
+	expected := NewFromFloat(dbvalue)
+	scanHelper(t, dbvalue, expected)
+
 	// apparently MySQL 5.7.16 and returns these as float32 so we need
 	// to handle these as well
 	dbvalueFloat32 := float32(54.33)
 	expected = NewFromFloat(float64(dbvalueFloat32))
-
-	err = a.Scan(dbvalueFloat32)
-	if err != nil {
-		// Scan failed... no need to test result value
-		t.Errorf("a.Scan(54.33) failed with message: %s", err)
-
-	} else {
-		// Scan succeeded... test resulting values
-		if !a.Equal(expected) {
-			t.Errorf("%s does not equal to %s", a, expected)
-		}
-	}
+	scanHelper(t, dbvalueFloat32, expected)
 
 	// at least SQLite returns an int64 when 0 is stored in the db
 	// and you specified a numeric format on the schema
 	dbvalueInt := int64(0)
 	expected = New(dbvalueInt, 0)
+	scanHelper(t, dbvalueInt, expected)
 
-	err = a.Scan(dbvalueInt)
-	if err != nil {
-		// Scan failed... no need to test result value
-		t.Errorf("a.Scan(0) failed with message: %s", err)
-
-	} else {
-		// Scan succeeded... test resulting values
-		if !a.Equal(expected) {
-			t.Errorf("%s does not equal to %s", a, expected)
-		}
-	}
+	// also test uint64
+	dbvalueUint64 := uint64(2)
+	expected = New(2, 0)
+	scanHelper(t, dbvalueUint64, expected)
 
 	// in case you specified a varchar in your SQL schema,
-	// the database driver will return byte slice []byte
+	// the database driver may return either []byte or string
 	valueStr := "535.666"
 	dbvalueStr := []byte(valueStr)
-	expected, err = NewFromString(valueStr)
+	expected, err := NewFromString(valueStr)
 	if err != nil {
 		t.Fatal(err)
 	}
-
-	err = a.Scan(dbvalueStr)
-	if err != nil {
-		// Scan failed... no need to test result value
-		t.Errorf("a.Scan('535.666') failed with message: %s", err)
-
-	} else {
-		// Scan succeeded... test resulting values
-		if !a.Equal(expected) {
-			t.Errorf("%s does not equal to %s", a, expected)
-		}
-	}
-
-	// lib/pq can also return strings
-	expected, err = NewFromString(valueStr)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	err = a.Scan(valueStr)
-	if err != nil {
-		// Scan failed... no need to test result value
-		t.Errorf("a.Scan('535.666') failed with message: %s", err)
-	} else {
-		// Scan succeeded... test resulting values
-		if !a.Equal(expected) {
-			t.Errorf("%s does not equal to %s", a, expected)
-		}
-	}
+	scanHelper(t, dbvalueStr, expected)
+	scanHelper(t, valueStr, expected)
 
 	type foo struct{}
+	a := Decimal{}
 	err = a.Scan(foo{})
 	if err == nil {
 		t.Errorf("a.Scan(Foo{}) should have thrown an error but did not")

go.mod

@@ -1,3 +1,3 @@
 module github.com/piyongcai/decimal
 
-go 1.7
+go 1.10