// Copyright 2017 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package number
import (
"fmt"
"math"
"strconv"
"strings"
"testing"
)
func mkfloat(num string) float64 {
u, _ := strconv.ParseUint(num, 10, 32)
return float64(u)
}
// mkdec creates a decimal from a string. All ASCII digits are converted to
// digits in the decimal. The dot is used to indicate the scale by which the
// digits are shifted. Numbers may have an additional exponent or be the special
// value NaN, Inf, or -Inf.
func mkdec(num string) (d Decimal) {
var r RoundingContext
d.Convert(r, dec(num))
return
}
type dec string
func (s dec) Convert(d *Decimal, _ RoundingContext) {
num := string(s)
if num[0] == '-' {
d.Neg = true
num = num[1:]
}
switch num {
case "NaN":
d.NaN = true
return
case "Inf":
d.Inf = true
return
}
if p := strings.IndexAny(num, "eE"); p != -1 {
i64, err := strconv.ParseInt(num[p+1:], 10, 32)
if err != nil {
panic(err)
}
d.Exp = int32(i64)
num = num[:p]
}
if p := strings.IndexByte(num, '.'); p != -1 {
d.Exp += int32(p)
num = num[:p] + num[p+1:]
} else {
d.Exp += int32(len(num))
}
d.Digits = []byte(num)
for i := range d.Digits {
d.Digits[i] -= '0'
}
*d = d.normalize()
}
func byteNum(s string) []byte {
b := make([]byte, len(s))
for i := 0; i < len(s); i++ {
if c := s[i]; '0' <= c && c <= '9' {
b[i] = s[i] - '0'
} else {
b[i] = s[i] - 'a' + 10
}
}
return b
}
func strNum(s string) string {
return string(byteNum(s))
}
func TestDecimalString(t *testing.T) {
for _, test := range []struct {
x Decimal
want string
}{
{want: "0"},
{Decimal{digits: digits{Digits: nil, Exp: 1000}}, "0"}, // exponent of 1000 is ignored
{Decimal{digits: digits{Digits: byteNum("12345"), Exp: 0}}, "0.12345"},
{Decimal{digits: digits{Digits: byteNum("12345"), Exp: -3}}, "0.00012345"},
{Decimal{digits: digits{Digits: byteNum("12345"), Exp: +3}}, "123.45"},
{Decimal{digits: digits{Digits: byteNum("12345"), Exp: +10}}, "1234500000"},
} {
if got := test.x.String(); got != test.want {
t.Errorf("%v == %q; want %q", test.x, got, test.want)
}
}
}
func TestRounding(t *testing.T) {
testCases := []struct {
x string
n int
// modes is the result for modes. Signs are left out of the result.
// The results are stored in the following order:
// zero, negInf
// nearZero, nearEven, nearAway
// away, posInf
modes [numModes]string
}{
{"0", 1, [numModes]string{
"0", "0",
"0", "0", "0",
"0", "0"}},
{"1", 1, [numModes]string{
"1", "1",
"1", "1", "1",
"1", "1"}},
{"5", 1, [numModes]string{
"5", "5",
"5", "5", "5",
"5", "5"}},
{"15", 1, [numModes]string{
"10", "10",
"10", "20", "20",
"20", "20"}},
{"45", 1, [numModes]string{
"40", "40",
"40", "40", "50",
"50", "50"}},
{"95", 1, [numModes]string{
"90", "90",
"90", "100", "100",
"100", "100"}},
{"12344999", 4, [numModes]string{
"12340000", "12340000",
"12340000", "12340000", "12340000",
"12350000", "12350000"}},
{"12345000", 4, [numModes]string{
"12340000", "12340000",
"12340000", "12340000", "12350000",
"12350000", "12350000"}},
{"12345001", 4, [numModes]string{
"12340000", "12340000",
"12350000", "12350000", "12350000",
"12350000", "12350000"}},
{"12345100", 4, [numModes]string{
"12340000", "12340000",
"12350000", "12350000", "12350000",
"12350000", "12350000"}},
{"23454999", 4, [numModes]string{
"23450000", "23450000",
"23450000", "23450000", "23450000",
"23460000", "23460000"}},
{"23455000", 4, [numModes]string{
"23450000", "23450000",
"23450000", "23460000", "23460000",
"23460000", "23460000"}},
{"23455001", 4, [numModes]string{
"23450000", "23450000",
"23460000", "23460000", "23460000",
"23460000", "23460000"}},
{"23455100", 4, [numModes]string{
"23450000", "23450000",
"23460000", "23460000", "23460000",
"23460000", "23460000"}},
{"99994999", 4, [numModes]string{
"99990000", "99990000",
"99990000", "99990000", "99990000",
"100000000", "100000000"}},
{"99995000", 4, [numModes]string{
"99990000", "99990000",
"99990000", "100000000", "100000000",
"100000000", "100000000"}},
{"99999999", 4, [numModes]string{
"99990000", "99990000",
"100000000", "100000000", "100000000",
"100000000", "100000000"}},
{"12994999", 4, [numModes]string{
"12990000", "12990000",
"12990000", "12990000", "12990000",
"13000000", "13000000"}},
{"12995000", 4, [numModes]string{
"12990000", "12990000",
"12990000", "13000000", "13000000",
"13000000", "13000000"}},
{"12999999", 4, [numModes]string{
"12990000", "12990000",
"13000000", "13000000", "13000000",
"13000000", "13000000"}},
}
modes := []RoundingMode{
ToZero, ToNegativeInf,
ToNearestZero, ToNearestEven, ToNearestAway,
AwayFromZero, ToPositiveInf,
}
for _, tc := range testCases {
// Create negative counterpart tests: the sign is reversed and
// ToPositiveInf and ToNegativeInf swapped.
negModes := tc.modes
negModes[1], negModes[6] = negModes[6], negModes[1]
for i, res := range negModes {
negModes[i] = "-" + res
}
for i, m := range modes {
t.Run(fmt.Sprintf("x:%s/n:%d/%s", tc.x, tc.n, m), func(t *testing.T) {
d := mkdec(tc.x)
d.round(m, tc.n)
if got := d.String(); got != tc.modes[i] {
t.Errorf("pos decimal: got %q; want %q", d.String(), tc.modes[i])
}
mult := math.Pow(10, float64(len(tc.x)-tc.n))
f := mkfloat(tc.x)
f = m.roundFloat(f/mult) * mult
if got := fmt.Sprintf("%.0f", f); got != tc.modes[i] {
t.Errorf("pos float: got %q; want %q", got, tc.modes[i])
}
// Test the negative case. This is the same as the positive
// case, but with ToPositiveInf and ToNegativeInf swapped.
d = mkdec(tc.x)
d.Neg = true
d.round(m, tc.n)
if got, want := d.String(), negModes[i]; got != want {
t.Errorf("neg decimal: got %q; want %q", d.String(), want)
}
f = -mkfloat(tc.x)
f = m.roundFloat(f/mult) * mult
if got := fmt.Sprintf("%.0f", f); got != negModes[i] {
t.Errorf("neg float: got %q; want %q", got, negModes[i])
}
})
}
}
}
func TestConvert(t *testing.T) {
scale2 := RoundingContext{}
scale2.SetScale(2)
scale2away := RoundingContext{Mode: AwayFromZero}
scale2away.SetScale(2)
inc0_05 := RoundingContext{Increment: 5, IncrementScale: 2}
inc0_05.SetScale(2)
inc50 := RoundingContext{Increment: 50}
prec3 := RoundingContext{}
prec3.SetPrecision(3)
roundShift := RoundingContext{DigitShift: 2, MaxFractionDigits: 2}
testCases := []struct {
x interface{}
rc RoundingContext
out string
}{
{-0.001, scale2, "-0.00"},
{0.1234, prec3, "0.123"},
{1234.0, prec3, "1230"},
{1.2345e10, prec3, "12300000000"},
{int8(-34), scale2, "-34"},
{int16(-234), scale2, "-234"},
{int32(-234), scale2, "-234"},
{int64(-234), scale2, "-234"},
{int(-234), scale2, "-234"},
{uint8(234), scale2, "234"},
{uint16(234), scale2, "234"},
{uint32(234), scale2, "234"},
{uint64(234), scale2, "234"},
{uint(234), scale2, "234"},
{-1e9, scale2, "-1000000000.00"},
// The following two causes this result to have a lot of digits:
// 1) 0.234 cannot be accurately represented as a float64, and
// 2) as strconv does not support the rounding AwayFromZero, Convert
// leaves the rounding to caller.
{0.234, scale2away,
"0.2340000000000000135447209004269097931683063507080078125"},
{0.0249, inc0_05, "0.00"},
{0.025, inc0_05, "0.00"},
{0.0251, inc0_05, "0.05"},
{0.03, inc0_05, "0.05"},
{0.049, inc0_05, "0.05"},
{0.05, inc0_05, "0.05"},
{0.051, inc0_05, "0.05"},
{0.0749, inc0_05, "0.05"},
{0.075, inc0_05, "0.10"},
{0.0751, inc0_05, "0.10"},
{324, inc50, "300"},
{325, inc50, "300"},
{326, inc50, "350"},
{349, inc50, "350"},
{350, inc50, "350"},
{351, inc50, "350"},
{374, inc50, "350"},
{375, inc50, "400"},
{376, inc50, "400"},
// Here the scale is 2, but the digits get shifted left. As we use
// AppendFloat to do the rounding an exta 0 gets added.
{0.123, roundShift, "0.1230"},
{converter(3), scale2, "100"},
{math.Inf(1), inc50, "Inf"},
{math.Inf(-1), inc50, "-Inf"},
{math.NaN(), inc50, "NaN"},
{"clearly not a number", scale2, "NaN"},
}
for _, tc := range testCases {
var d Decimal
t.Run(fmt.Sprintf("%T:%v-%v", tc.x, tc.x, tc.rc), func(t *testing.T) {
d.Convert(tc.rc, tc.x)
if got := d.String(); got != tc.out {
t.Errorf("got %q; want %q", got, tc.out)
}
})
}
}
type converter int
func (c converter) Convert(d *Decimal, r RoundingContext) {
d.Digits = append(d.Digits, 1, 0, 0)
d.Exp = 3
}
