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// Copyright 2017 The Hugo Authors. All rights reserved.
//
// 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 math
import (
"errors"
"math"
"reflect"
"github.com/spf13/cast"
)
// New returns a new instance of the math-namespaced template functions.
func New() *Namespace {
return &Namespace{}
}
// Namespace provides template functions for the "math" namespace.
type Namespace struct{}
// Add adds two numbers.
func (ns *Namespace) Add(a, b interface{}) (interface{}, error) {
return DoArithmetic(a, b, '+')
}
// Div divides two numbers.
func (ns *Namespace) Div(a, b interface{}) (interface{}, error) {
return DoArithmetic(a, b, '/')
}
// Log returns the natural logarithm of a number.
func (ns *Namespace) Log(a interface{}) (float64, error) {
af, err := cast.ToFloat64E(a)
if err != nil {
return 0, errors.New("Log operator can't be used with non integer or float value")
}
return math.Log(af), nil
}
// Mod returns a % b.
func (ns *Namespace) Mod(a, b interface{}) (int64, error) {
av := reflect.ValueOf(a)
bv := reflect.ValueOf(b)
var ai, bi int64
switch av.Kind() {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
ai = av.Int()
default:
return 0, errors.New("Modulo operator can't be used with non integer value")
}
switch bv.Kind() {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
bi = bv.Int()
default:
return 0, errors.New("Modulo operator can't be used with non integer value")
}
if bi == 0 {
return 0, errors.New("The number can't be divided by zero at modulo operation")
}
return ai % bi, nil
}
// ModBool returns the boolean of a % b. If a % b == 0, return true.
func (ns *Namespace) ModBool(a, b interface{}) (bool, error) {
res, err := ns.Mod(a, b)
if err != nil {
return false, err
}
return res == int64(0), nil
}
// Mul multiplies two numbers.
func (ns *Namespace) Mul(a, b interface{}) (interface{}, error) {
return DoArithmetic(a, b, '*')
}
// Sub substracts two numbers.
func (ns *Namespace) Sub(a, b interface{}) (interface{}, error) {
return DoArithmetic(a, b, '-')
}
// DoArithmetic performs arithmetic operations (+,-,*,/) using reflection to
// determine the type of the two terms.
func DoArithmetic(a, b interface{}, op rune) (interface{}, error) {
av := reflect.ValueOf(a)
bv := reflect.ValueOf(b)
var ai, bi int64
var af, bf float64
var au, bu uint64
switch av.Kind() {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
ai = av.Int()
switch bv.Kind() {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
bi = bv.Int()
case reflect.Float32, reflect.Float64:
af = float64(ai) // may overflow
ai = 0
bf = bv.Float()
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
bu = bv.Uint()
if ai >= 0 {
au = uint64(ai)
ai = 0
} else {
bi = int64(bu) // may overflow
bu = 0
}
default:
return nil, errors.New("Can't apply the operator to the values")
}
case reflect.Float32, reflect.Float64:
af = av.Float()
switch bv.Kind() {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
bf = float64(bv.Int()) // may overflow
case reflect.Float32, reflect.Float64:
bf = bv.Float()
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
bf = float64(bv.Uint()) // may overflow
default:
return nil, errors.New("Can't apply the operator to the values")
}
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
au = av.Uint()
switch bv.Kind() {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
bi = bv.Int()
if bi >= 0 {
bu = uint64(bi)
bi = 0
} else {
ai = int64(au) // may overflow
au = 0
}
case reflect.Float32, reflect.Float64:
af = float64(au) // may overflow
au = 0
bf = bv.Float()
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
bu = bv.Uint()
default:
return nil, errors.New("Can't apply the operator to the values")
}
case reflect.String:
as := av.String()
if bv.Kind() == reflect.String && op == '+' {
bs := bv.String()
return as + bs, nil
}
return nil, errors.New("Can't apply the operator to the values")
default:
return nil, errors.New("Can't apply the operator to the values")
}
switch op {
case '+':
if ai != 0 || bi != 0 {
return ai + bi, nil
} else if af != 0 || bf != 0 {
return af + bf, nil
} else if au != 0 || bu != 0 {
return au + bu, nil
}
return 0, nil
case '-':
if ai != 0 || bi != 0 {
return ai - bi, nil
} else if af != 0 || bf != 0 {
return af - bf, nil
} else if au != 0 || bu != 0 {
return au - bu, nil
}
return 0, nil
case '*':
if ai != 0 || bi != 0 {
return ai * bi, nil
} else if af != 0 || bf != 0 {
return af * bf, nil
} else if au != 0 || bu != 0 {
return au * bu, nil
}
return 0, nil
case '/':
if bi != 0 {
return ai / bi, nil
} else if bf != 0 {
return af / bf, nil
} else if bu != 0 {
return au / bu, nil
}
return nil, errors.New("Can't divide the value by 0")
default:
return nil, errors.New("There is no such an operation")
}
}
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