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Copy pathnumeric.go
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285 lines (260 loc) · 6.11 KB
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package plush
import (
"fmt"
"math"
"reflect"
)
type numericKind int
const (
numericSigned numericKind = iota
numericUnsigned
numericFloat
)
type numericValue struct {
kind numericKind
i int64
u uint64
f float64
}
func isNumericOperator(op string) bool {
switch op {
case "+", "-", "*", "/", "<", ">", "<=", ">=", "==", "!=":
return true
default:
return false
}
}
func numericValueFromGo(value interface{}) (numericValue, bool) {
if value == nil {
return numericValue{}, false
}
rv := reflect.ValueOf(value)
for rv.Kind() == reflect.Interface {
if rv.IsNil() {
return numericValue{}, false
}
rv = rv.Elem()
}
switch rv.Kind() {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
return numericValue{kind: numericSigned, i: rv.Int()}, true
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
return numericValue{kind: numericUnsigned, u: rv.Uint()}, true
case reflect.Float32, reflect.Float64:
return numericValue{kind: numericFloat, f: rv.Convert(reflect.TypeOf(float64(0))).Float()}, true
default:
return numericValue{}, false
}
}
func evalNumericOperator(left, right numericValue, op string) (interface{}, error) {
switch op {
case "==":
return compareNumericEquality(left, right), nil
case "!=":
return !compareNumericEquality(left, right), nil
case "<", ">", "<=", ">=":
return compareNumericOrdered(op, left, right)
default:
return numericArithmetic(left, right, op)
}
}
func (n numericValue) float64() float64 {
switch n.kind {
case numericFloat:
return n.f
case numericUnsigned:
return float64(n.u)
default:
return float64(n.i)
}
}
func (n numericValue) int64() (int64, bool) {
switch n.kind {
case numericSigned:
return n.i, true
case numericUnsigned:
if n.u <= uint64(math.MaxInt64) {
return int64(n.u), true
}
}
return 0, false
}
func (n numericValue) uint64() (uint64, bool) {
switch n.kind {
case numericUnsigned:
return n.u, true
case numericSigned:
if n.i >= 0 {
return uint64(n.i), true
}
}
return 0, false
}
func compareNumericEquality(left, right numericValue) bool {
if left.kind == numericFloat || right.kind == numericFloat {
return left.float64() == right.float64()
}
if l, ok := left.int64(); ok {
if r, ok := right.int64(); ok {
return l == r
}
}
if left.kind == numericSigned && left.i < 0 {
return false
}
if right.kind == numericSigned && right.i < 0 {
return false
}
l, lok := left.uint64()
r, rok := right.uint64()
return lok && rok && l == r
}
func compareNumericOrdered(op string, left, right numericValue) (bool, error) {
if left.kind == numericFloat || right.kind == numericFloat {
l := left.float64()
r := right.float64()
switch op {
case "<":
return l < r, nil
case ">":
return l > r, nil
case "<=":
return l <= r, nil
case ">=":
return l >= r, nil
}
}
if left.kind == numericSigned && right.kind == numericSigned {
switch op {
case "<":
return left.i < right.i, nil
case ">":
return left.i > right.i, nil
case "<=":
return left.i <= right.i, nil
case ">=":
return left.i >= right.i, nil
}
}
if left.kind == numericUnsigned && right.kind == numericUnsigned {
return compareUintOrdered(op, left.u, right.u)
}
if left.kind == numericSigned {
if left.i < 0 {
switch op {
case "<":
return true, nil
case ">":
return false, nil
case "<=":
return true, nil
case ">=":
return false, nil
}
}
return compareUintOrdered(op, uint64(left.i), right.u)
}
if right.i < 0 {
switch op {
case "<":
return false, nil
case ">":
return true, nil
case "<=":
return false, nil
case ">=":
return true, nil
}
}
return compareUintOrdered(op, left.u, uint64(right.i))
}
func compareUintOrdered(op string, left, right uint64) (bool, error) {
switch op {
case "<":
return left < right, nil
case ">":
return left > right, nil
case "<=":
return left <= right, nil
case ">=":
return left >= right, nil
default:
return false, fmt.Errorf("unknown operator for numeric %s", op)
}
}
func numericArithmetic(left, right numericValue, op string) (interface{}, error) {
if left.kind == numericFloat || right.kind == numericFloat {
l := left.float64()
r := right.float64()
switch op {
case "+":
return l + r, nil
case "-":
return l - r, nil
case "*":
return l * r, nil
case "/":
if r == 0 {
return nil, fmt.Errorf("division by zero %v %s %v", l, op, r)
}
return l / r, nil
default:
return nil, fmt.Errorf("unknown operator for numeric %s", op)
}
}
lSigned, lok := left.int64()
rSigned, rok := right.int64()
if lok && rok {
switch op {
case "+":
return signedNumericResult(lSigned + rSigned), nil
case "-":
return signedNumericResult(lSigned - rSigned), nil
case "*":
return signedNumericResult(lSigned * rSigned), nil
case "/":
if rSigned == 0 {
return nil, fmt.Errorf("division by zero %v %s %v", lSigned, op, rSigned)
}
return signedNumericResult(lSigned / rSigned), nil
default:
return nil, fmt.Errorf("unknown operator for numeric %s", op)
}
}
lUnsigned, lok := left.uint64()
rUnsigned, rok := right.uint64()
if !lok || !rok {
return nil, fmt.Errorf("unsupported mixed signed/unsigned operation")
}
switch op {
case "+":
if math.MaxUint64-lUnsigned < rUnsigned {
return nil, fmt.Errorf("integer overflow %v + %v", lUnsigned, rUnsigned)
}
return lUnsigned + rUnsigned, nil
case "-":
if lUnsigned < rUnsigned {
return nil, fmt.Errorf("integer underflow %v - %v", lUnsigned, rUnsigned)
}
return lUnsigned - rUnsigned, nil
case "*":
if rUnsigned != 0 && lUnsigned > math.MaxUint64/rUnsigned {
return nil, fmt.Errorf("integer overflow %v * %v", lUnsigned, rUnsigned)
}
return lUnsigned * rUnsigned, nil
case "/":
if rUnsigned == 0 {
return nil, fmt.Errorf("division by zero %v / %v", lUnsigned, rUnsigned)
}
return lUnsigned / rUnsigned, nil
default:
return nil, fmt.Errorf("unknown operator for numeric %s", op)
}
}
func signedNumericResult(value int64) interface{} {
asInt := int(value)
if int64(asInt) == value {
return asInt
}
return value
}