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// Copyright 2020 CUE Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package adt
import (
"math/big"
"github.com/cockroachdb/apd/v2"
)
var apdCtx apd.Context
func init() {
apdCtx = apd.BaseContext
apdCtx.Precision = 24
}
func (n *Num) Impl() *apd.Decimal {
return &n.X
}
func (n *Num) Negative() bool {
return n.X.Negative
}
func (a *Num) Cmp(b *Num) int {
return a.X.Cmp(&b.X)
}
func (c *OpContext) Add(a, b *Num) Value {
return numOp(c, apdCtx.Add, a, b)
}
func (c *OpContext) Sub(a, b *Num) Value {
return numOp(c, apdCtx.Sub, a, b)
}
func (c *OpContext) Mul(a, b *Num) Value {
return numOp(c, apdCtx.Mul, a, b)
}
func (c *OpContext) Quo(a, b *Num) Value {
v := numOp(c, apdCtx.Quo, a, b)
if n, ok := v.(*Num); ok {
n.K = FloatKind
}
return v
}
func (c *OpContext) Pow(a, b *Num) Value {
return numOp(c, apdCtx.Pow, a, b)
}
type numFunc func(z, x, y *apd.Decimal) (apd.Condition, error)
func numOp(c *OpContext, fn numFunc, x, y *Num) Value {
var d apd.Decimal
cond, err := fn(&d, &x.X, &y.X)
if err != nil {
return c.NewErrf("failed arithmetic: %v", err)
}
if cond.DivisionByZero() {
return c.NewErrf("division by zero")
}
k := x.Kind() & y.Kind()
if k == 0 {
k = FloatKind
}
return c.newNum(&d, k)
}
func (c *OpContext) IntDiv(a, b *Num) Value {
return intDivOp(c, (*big.Int).Div, a, b)
}
func (c *OpContext) IntMod(a, b *Num) Value {
return intDivOp(c, (*big.Int).Mod, a, b)
}
func (c *OpContext) IntQuo(a, b *Num) Value {
return intDivOp(c, (*big.Int).Quo, a, b)
}
func (c *OpContext) IntRem(a, b *Num) Value {
return intDivOp(c, (*big.Int).Rem, a, b)
}
type intFunc func(z, x, y *big.Int) *big.Int
func intDivOp(c *OpContext, fn intFunc, a, b *Num) Value {
if b.X.IsZero() {
return c.NewErrf("division by zero")
}
var x, y apd.Decimal
_, _ = apdCtx.RoundToIntegralValue(&x, &a.X)
if x.Negative {
x.Coeff.Neg(&x.Coeff)
}
_, _ = apdCtx.RoundToIntegralValue(&y, &b.X)
if y.Negative {
y.Coeff.Neg(&y.Coeff)
}
var d apd.Decimal
fn(&d.Coeff, &x.Coeff, &y.Coeff)
if d.Coeff.Sign() < 0 {
d.Coeff.Neg(&d.Coeff)
d.Negative = true
}
return c.newNum(&d, IntKind)
}