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//This package is copied from Go library text/template.
//The original private functions eq, ge, gt, le, lt, and ne
//are exported as public functions.
package template
import (
"errors"
"reflect"
)
var (
errBadComparisonType = errors.New("invalid type for comparison")
errBadComparison = errors.New("incompatible types for comparison")
errNoComparison = errors.New("missing argument for comparison")
)
type kind int
const (
invalidKind kind = iota
boolKind
complexKind
intKind
floatKind
integerKind
stringKind
uintKind
)
func basicKind(v reflect.Value) (kind, error) {
switch v.Kind() {
case reflect.Bool:
return boolKind, nil
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
return intKind, nil
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
return uintKind, nil
case reflect.Float32, reflect.Float64:
return floatKind, nil
case reflect.Complex64, reflect.Complex128:
return complexKind, nil
case reflect.String:
return stringKind, nil
}
return invalidKind, errBadComparisonType
}
// Equal evaluates the comparison a == b || a == c || ...
func Equal(arg1 interface{}, arg2 ...interface{}) (bool, error) {
v1 := reflect.ValueOf(arg1)
k1, err := basicKind(v1)
if err != nil {
return false, err
}
if len(arg2) == 0 {
return false, errNoComparison
}
for _, arg := range arg2 {
v2 := reflect.ValueOf(arg)
k2, err := basicKind(v2)
if err != nil {
return false, err
}
truth := false
if k1 != k2 {
// Special case: Can compare integer values regardless of type's sign.
switch {
case k1 == intKind && k2 == uintKind:
truth = v1.Int() >= 0 && uint64(v1.Int()) == v2.Uint()
case k1 == uintKind && k2 == intKind:
truth = v2.Int() >= 0 && v1.Uint() == uint64(v2.Int())
default:
return false, errBadComparison
}
} else {
switch k1 {
case boolKind:
truth = v1.Bool() == v2.Bool()
case complexKind:
truth = v1.Complex() == v2.Complex()
case floatKind:
truth = v1.Float() == v2.Float()
case intKind:
truth = v1.Int() == v2.Int()
case stringKind:
truth = v1.String() == v2.String()
case uintKind:
truth = v1.Uint() == v2.Uint()
default:
panic("invalid kind")
}
}
if truth {
return true, nil
}
}
return false, nil
}
// NotEqual evaluates the comparison a != b.
func NotEqual(arg1, arg2 interface{}) (bool, error) {
// != is the inverse of ==.
equal, err := Equal(arg1, arg2)
return !equal, err
}
// Less evaluates the comparison a < b.
func Less(arg1, arg2 interface{}) (bool, error) {
v1 := reflect.ValueOf(arg1)
k1, err := basicKind(v1)
if err != nil {
return false, err
}
v2 := reflect.ValueOf(arg2)
k2, err := basicKind(v2)
if err != nil {
return false, err
}
truth := false
if k1 != k2 {
// Special case: Can compare integer values regardless of type's sign.
switch {
case k1 == intKind && k2 == uintKind:
truth = v1.Int() < 0 || uint64(v1.Int()) < v2.Uint()
case k1 == uintKind && k2 == intKind:
truth = v2.Int() >= 0 && v1.Uint() < uint64(v2.Int())
default:
return false, errBadComparison
}
} else {
switch k1 {
case boolKind, complexKind:
return false, errBadComparisonType
case floatKind:
truth = v1.Float() < v2.Float()
case intKind:
truth = v1.Int() < v2.Int()
case stringKind:
truth = v1.String() < v2.String()
case uintKind:
truth = v1.Uint() < v2.Uint()
default:
panic("invalid kind")
}
}
return truth, nil
}
// LessEqual evaluates the comparison <= b.
func LessEqual(arg1, arg2 interface{}) (bool, error) {
// <= is < or ==.
lessThan, err := Less(arg1, arg2)
if lessThan || err != nil {
return lessThan, err
}
return Equal(arg1, arg2)
}
// Greater evaluates the comparison a > b.
func Greater(arg1, arg2 interface{}) (bool, error) {
// > is the inverse of <=.
lessOrEqual, err := LessEqual(arg1, arg2)
if err != nil {
return false, err
}
return !lessOrEqual, nil
}
// GreaterEqual evaluates the comparison a >= b.
func GreaterEqual(arg1, arg2 interface{}) (bool, error) {
// >= is the inverse of <.
lessThan, err := Less(arg1, arg2)
if err != nil {
return false, err
}
return !lessThan, nil
}
|
