Golang Dec.SetString方法代码示例

func TestDecGobEncoding(t *testing.T) {
	var medium bytes.Buffer
	enc := gob.NewEncoder(&medium)
	dec := gob.NewDecoder(&medium)
	for i, test := range decGobEncodingTests {
		for j := 0; j < 2; j++ {
			for k := inf.Scale(-5); k <= 5; k++ {
				medium.Reset() // empty buffer for each test case (in case of failures)
				stest := test
				if j != 0 {
					// negative numbers
					stest = "-" + test
				}
				var tx inf.Dec
				tx.SetString(stest)
				tx.SetScale(k) // test with positive, negative, and zero scale
				if err := enc.Encode(&tx); err != nil {
					t.Errorf("#%d%c: encoding failed: %s", i, 'a'+j, err)
				}
				var rx inf.Dec
				if err := dec.Decode(&rx); err != nil {
					t.Errorf("#%d%c: decoding failed: %s", i, 'a'+j, err)
				}
				if rx.Cmp(&tx) != 0 {
					t.Errorf("#%d%c: transmission failed: got %s want %s", i, 'a'+j, &rx, &tx)
				}
			}
		}
	}
}

// ParseQuantity turns str into a Quantity, or returns an error.
func ParseQuantity(str string) (*Quantity, error) {
	parts := splitRE.FindStringSubmatch(strings.TrimSpace(str))
	// regexp returns are entire match, followed by an entry for each () section.
	if len(parts) != 3 {
		return nil, ErrFormatWrong
	}

	amount := new(inf.Dec)
	if _, ok := amount.SetString(parts[1]); !ok {
		return nil, ErrNumeric
	}

	base, exponent, format, ok := quantitySuffixer.interpret(suffix(parts[2]))
	if !ok {
		return nil, ErrSuffix
	}

	// So that no one but us has to think about suffixes, remove it.
	if base == 10 {
		amount.SetScale(amount.Scale() + inf.Scale(-exponent))
	} else if base == 2 {
		// numericSuffix = 2 ** exponent
		numericSuffix := big.NewInt(1).Lsh(bigOne, uint(exponent))
		ub := amount.UnscaledBig()
		amount.SetUnscaledBig(ub.Mul(ub, numericSuffix))
	}

	// Cap at min/max bounds.
	sign := amount.Sign()
	if sign == -1 {
		amount.Neg(amount)
	}
	// This rounds non-zero values up to the minimum representable
	// value, under the theory that if you want some resources, you
	// should get some resources, even if you asked for way too small
	// of an amount.
	// Arguably, this should be inf.RoundHalfUp (normal rounding), but
	// that would have the side effect of rounding values < .5m to zero.
	if v, ok := amount.Unscaled(); v != int64(0) || !ok {
		amount.Round(amount, 3, inf.RoundUp)
	}

	// The max is just a simple cap.
	if amount.Cmp(maxAllowed) > 0 {
		amount.Set(maxAllowed)
	}
	if format == BinarySI && amount.Cmp(decOne) < 0 && amount.Cmp(decZero) > 0 {
		// This avoids rounding and hopefully confusion, too.
		format = DecimalSI
	}
	if sign == -1 {
		amount.Neg(amount)
	}

	return &Quantity{amount, format}, nil
}

func TestDecSetString(t *testing.T) {
	tmp := new(inf.Dec)
	for i, test := range decStringTests {
		if test.scale < 0 {
			// SetString only supports scale >= 0
			continue
		}
		// initialize to a non-zero value so that issues with parsing
		// 0 are detected
		tmp.Set(inf.NewDec(1234567890, 123))
		n1, ok1 := new(inf.Dec).SetString(test.in)
		n2, ok2 := tmp.SetString(test.in)
		expected := inf.NewDec(test.val, test.scale)
		if ok1 != test.ok || ok2 != test.ok {
			t.Errorf("#%d (input '%s') ok incorrect (should be %t)", i, test.in, test.ok)
			continue
		}
		if !ok1 {
			if n1 != nil {
				t.Errorf("#%d (input '%s') n1 != nil", i, test.in)
			}
			continue
		}
		if !ok2 {
			if n2 != nil {
				t.Errorf("#%d (input '%s') n2 != nil", i, test.in)
			}
			continue
		}

		if n1.Cmp(expected) != 0 {
			t.Errorf("#%d (input '%s') got: %s want: %d", i, test.in, n1, test.val)
		}
		if n2.Cmp(expected) != 0 {
			t.Errorf("#%d (input '%s') got: %s want: %d", i, test.in, n2, test.val)
		}
	}
}

func TestLowLevelAPIOnly(t *testing.T) {

	type CDR struct {
		Imsi      string
		Timestamp time.Time
		Duration  int64
		Carrier   string
		Cost      *inf.Dec
	}

	strat := func(c gocql.ColumnInfo) (reflect.StructField, bool) {
		st := reflect.TypeOf((*CDR)(nil)).Elem()
		switch c.Name {
		case "imsi":
			return st.FieldByName("Imsi")
		case "timestamp":
			return st.FieldByName("Timestamp")
		case "duration":
			return st.FieldByName("Duration")
		case "carrier":
			return st.FieldByName("Carrier")
		case "charge":
			return st.FieldByName("Cost")
		default:
			return reflect.StructField{}, false
		}
	}

	s := setup(t, "calls")

	measurements := 43

	start := time.Now()

	for i := 0; i < measurements; i++ {

		cost := new(inf.Dec)
		cost.SetString(fmt.Sprintf("1.0%d", i))

		cdr := CDR{
			Imsi:      "240080852000132",
			Timestamp: start.Add(time.Duration(i) * time.Millisecond),
			Duration:  int64(i) + 60,
			Carrier:   "TMOB",
			Cost:      cost,
		}

		if err := Bind(`INSERT INTO calls (imsi, timestamp, duration, carrier, charge) VALUES (?, ?, ?, ?, ?)`, cdr).Use(strat).Exec(s); err != nil {
			t.Fatal(err)
		}
	}

	q := s.Query(`SELECT imsi, timestamp, duration, carrier, charge FROM calls`)

	b := BindQuery(q).Use(strat)

	count := 0
	var r CDR

	for b.Scan(&r) {
		count++
		assert.Equal(t, "TMOB", r.Carrier)
	}

	err := b.Close()
	assert.Nil(t, err, "Could not close binding")
	assert.Equal(t, measurements, count)
}

func ExampleDec_SetString() {
	d := new(inf.Dec)
	d.SetString("012345.67890") // decimal; leading 0 ignored; trailing 0 kept
	fmt.Println(d)
	// Output: 12345.67890
}