add uint support

decimal.go

@@ -25,6 +25,8 @@ import (
 	"regexp"
 	"strconv"
 	"strings"
+
+	"github.com/holiman/uint256"
 )
 
 // DivisionPrecision is the number of decimal places in the result when it
@@ -98,6 +100,29 @@ func NewFromInt(value int64) Decimal {
 	}
 }
 
+// NewFromUint converts a uint256.Int to Decimal.
+// Example:
+//
+//     NewFromInt(uint256.NewInt(123)).String() // output: "123"
+func NewFromUint(u *uint256.Int) Decimal {
+	return Decimal{
+		value: u.ToBig(),
+		exp:   0,
+	}
+}
+
+// NewFromUintExp converts a Uint to Decimal with given exponent
+//
+// Example:
+//
+//     NewFromInt(uint256.NewInt(1), 2).String() // output: "100"
+func NewFromUintExp(u *uint256.Int, exp int32) Decimal {
+	return Decimal{
+		value: u.ToBig(),
+		exp:   exp,
+	}
+}
+
 // NewFromInt32 converts a int32 to Decimal.
 //
 // Example:
@@ -797,6 +822,21 @@ func (d Decimal) Rat() *big.Rat {
 	return new(big.Rat).SetFrac(num, oneInt)
 }
 
+// Uint returns integer component of the decimal as a uint256.Int.
+func (d Decimal) Uint() (*uint256.Int, bool) {
+	i := &big.Int{}
+	i.SetString(d.rescale(0).String(), 10)
+	return uint256.FromBig(i)
+}
+
+// UintNO returns integer component of the decimal as a uint256.Int.
+// NO stands for No Overflow. Ignore the bool indicating whether or not
+// overflow occured.
+func (d Decimal) UintNO() *uint256.Int {
+	u, _ := d.Uint()
+	return u
+}
+
 // Float64 returns the nearest float64 value for d and a bool indicating
 // whether f represents d exactly.
 // For more details, see the documentation for big.Rat.Float64

decimal_test.go

@@ -15,6 +15,8 @@ import (
 	"testing"
 	"testing/quick"
 	"time"
+
+	"github.com/holiman/uint256"
 )
 
 type testEnt struct {
@@ -2241,6 +2243,43 @@ func TestBigInt(t *testing.T) {
 	}
 }
 
+func TestUint(t *testing.T) {
+	testCases := []struct {
+		Dec     string
+		UintRep string
+	}{
+		{"0.0", "0"},
+		{"0.00000", "0"},
+		{"0.01", "0"},
+		{"12.1", "12"},
+		{"9999.999", "9999"},
+		// {"-32768.01234", "-32768"},
+		// {"-572372.0000000001", "-572372"},
+	}
+	for _, testCase := range testCases {
+		d, err := NewFromString(testCase.Dec)
+		if err != nil {
+			t.Fatal(err)
+		}
+		bi := &big.Int{}
+		bi.SetString(testCase.UintRep, 10)
+		exp, ok := uint256.FromBig(bi)
+		got, ok2 := d.Uint()
+		if ok != ok2 {
+			t.Fatalf("overflow from string (%v) <> vs from decimal (%v)", ok, ok2)
+		}
+		if !exp.Eq(got) {
+			t.Fatalf("expected %s == %s", exp, got)
+		}
+		if !ok {
+			if got = d.UintNO(); !exp.Eq(got) {
+				t.Fatalf("UintNO: expected %s == %s", exp, got)
+			}
+
+		}
+	}
+}
+
 func TestBigFloat(t *testing.T) {
 	testCases := []struct {
 		Dec         string

go.mod

@@ -1,3 +1,5 @@
 module github.com/shopspring/decimal
 
 go 1.13
+
+require github.com/holiman/uint256 v1.2.0 // indirect