niki/vendor/github.com/go-ozzo/ozzo-validation/length.go

// Copyright 2016 Qiang Xue. All rights reserved.

// Use of this source code is governed by a MIT-style

// license that can be found in the LICENSE file.

package validation

import (
	"errors"
	"fmt"
	"unicode/utf8"
)

// Length returns a validation rule that checks if a value's length is within the specified range.

// If max is 0, it means there is no upper bound for the length.

// This rule should only be used for validating strings, slices, maps, and arrays.

// An empty value is considered valid. Use the Required rule to make sure a value is not empty.

func Length(min, max int) *LengthRule {

	message := "the value must be empty"

	if min == 0 && max > 0 {

		message = fmt.Sprintf("the length must be no more than %v", max)

	} else if min > 0 && max == 0 {

		message = fmt.Sprintf("the length must be no less than %v", min)

	} else if min > 0 && max > 0 {

		if min == max {

			message = fmt.Sprintf("the length must be exactly %v", min)

		} else {

			message = fmt.Sprintf("the length must be between %v and %v", min, max)

		}

	}

	return &LengthRule{

		min: min,

		max: max,

		message: message,
	}

}

// RuneLength returns a validation rule that checks if a string's rune length is within the specified range.

// If max is 0, it means there is no upper bound for the length.

// This rule should only be used for validating strings, slices, maps, and arrays.

// An empty value is considered valid. Use the Required rule to make sure a value is not empty.

// If the value being validated is not a string, the rule works the same as Length.

func RuneLength(min, max int) *LengthRule {

	r := Length(min, max)

	r.rune = true

	return r

}

type LengthRule struct {
	min, max int

	message string

	rune bool
}

// Validate checks if the given value is valid or not.

func (v *LengthRule) Validate(value interface{}) error {

	value, isNil := Indirect(value)

	if isNil || IsEmpty(value) {

		return nil

	}

	var (
		l int

		err error
	)

	if s, ok := value.(string); ok && v.rune {

		l = utf8.RuneCountInString(s)

	} else if l, err = LengthOfValue(value); err != nil {

		return err

	}

	if v.min > 0 && l < v.min || v.max > 0 && l > v.max {

		return errors.New(v.message)

	}

	return nil

}

// Error sets the error message for the rule.

func (v *LengthRule) Error(message string) *LengthRule {

	v.message = message

	return v

}