cast/caste.go

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// Copyright © 2014 Steve Francia <spf@spf13.com>.
//
// Use of this source code is governed by an MIT-style
// license that can be found in the LICENSE file.
package cast
import (
"fmt"
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"html/template"
"reflect"
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"strconv"
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"strings"
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"time"
jww "github.com/spf13/jwalterweatherman"
)
// ToTimeE casts an empty interface to time.Time.
func ToTimeE(i interface{}) (tim time.Time, err error) {
i = indirect(i)
jww.DEBUG.Println("ToTimeE called on type:", reflect.TypeOf(i))
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switch s := i.(type) {
case time.Time:
return s, nil
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case string:
d, e := StringToDate(s)
if e == nil {
return d, nil
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}
return time.Time{}, fmt.Errorf("Could not parse Date/Time format: %v\n", e)
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default:
return time.Time{}, fmt.Errorf("Unable to Cast %#v to Time\n", i)
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}
}
// ToDurationE casts an empty interface to time.Duration.
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func ToDurationE(i interface{}) (d time.Duration, err error) {
i = indirect(i)
jww.DEBUG.Println("ToDurationE called on type:", reflect.TypeOf(i))
switch s := i.(type) {
case time.Duration:
return s, nil
case string:
d, err = time.ParseDuration(s)
return
default:
err = fmt.Errorf("Unable to Cast %#v to Duration\n", i)
return
}
}
// ToBoolE casts an empty interface to a bool.
func ToBoolE(i interface{}) (bool, error) {
i = indirect(i)
jww.DEBUG.Println("ToBoolE called on type:", reflect.TypeOf(i))
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switch b := i.(type) {
case bool:
return b, nil
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case nil:
return false, nil
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case int:
if i.(int) != 0 {
return true, nil
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}
return false, nil
case string:
return strconv.ParseBool(i.(string))
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default:
return false, fmt.Errorf("Unable to Cast %#v to bool", i)
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}
}
// ToFloat64E casts an empty interface to a float64.
func ToFloat64E(i interface{}) (float64, error) {
i = indirect(i)
jww.DEBUG.Println("ToFloat64E called on type:", reflect.TypeOf(i))
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switch s := i.(type) {
case float64:
return s, nil
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case float32:
return float64(s), nil
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case int64:
return float64(s), nil
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case int32:
return float64(s), nil
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case int16:
return float64(s), nil
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case int8:
return float64(s), nil
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case int:
return float64(s), nil
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case string:
v, err := strconv.ParseFloat(s, 64)
if err == nil {
return float64(v), nil
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}
return 0.0, fmt.Errorf("Unable to Cast %#v to float", i)
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default:
return 0.0, fmt.Errorf("Unable to Cast %#v to float", i)
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}
}
// ToIntE casts an empty interface to an int.
func ToIntE(i interface{}) (int, error) {
i = indirect(i)
jww.DEBUG.Println("ToIntE called on type:", reflect.TypeOf(i))
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switch s := i.(type) {
case int:
return s, nil
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case int64:
return int(s), nil
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case int32:
return int(s), nil
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case int16:
return int(s), nil
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case int8:
return int(s), nil
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case string:
v, err := strconv.ParseInt(s, 0, 0)
if err == nil {
return int(v), nil
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}
return 0, fmt.Errorf("Unable to Cast %#v to int", i)
case float64:
return int(s), nil
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case bool:
if bool(s) {
return 1, nil
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}
return 0, nil
case nil:
return 0, nil
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default:
return 0, fmt.Errorf("Unable to Cast %#v to int", i)
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}
}
// From html/template/content.go
// Copyright 2011 The Go Authors. All rights reserved.
// indirect returns the value, after dereferencing as many times
// as necessary to reach the base type (or nil).
func indirect(a interface{}) interface{} {
if a == nil {
return nil
}
if t := reflect.TypeOf(a); t.Kind() != reflect.Ptr {
// Avoid creating a reflect.Value if it's not a pointer.
return a
}
v := reflect.ValueOf(a)
for v.Kind() == reflect.Ptr && !v.IsNil() {
v = v.Elem()
}
return v.Interface()
}
// From html/template/content.go
// Copyright 2011 The Go Authors. All rights reserved.
// indirectToStringerOrError returns the value, after dereferencing as many times
// as necessary to reach the base type (or nil) or an implementation of fmt.Stringer
// or error,
func indirectToStringerOrError(a interface{}) interface{} {
if a == nil {
return nil
}
var errorType = reflect.TypeOf((*error)(nil)).Elem()
var fmtStringerType = reflect.TypeOf((*fmt.Stringer)(nil)).Elem()
v := reflect.ValueOf(a)
for !v.Type().Implements(fmtStringerType) && !v.Type().Implements(errorType) && v.Kind() == reflect.Ptr && !v.IsNil() {
v = v.Elem()
}
return v.Interface()
}
// ToStringE casts an empty interface to a string.
func ToStringE(i interface{}) (string, error) {
i = indirectToStringerOrError(i)
jww.DEBUG.Println("ToStringE called on type:", reflect.TypeOf(i))
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switch s := i.(type) {
case string:
return s, nil
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case float64:
return strconv.FormatFloat(i.(float64), 'f', -1, 64), nil
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case int:
return strconv.FormatInt(int64(i.(int)), 10), nil
case []byte:
return string(s), nil
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case template.HTML:
return string(s), nil
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case template.URL:
return string(s), nil
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case nil:
return "", nil
case fmt.Stringer:
return s.String(), nil
case error:
return s.Error(), nil
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default:
return "", fmt.Errorf("Unable to Cast %#v to string", i)
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}
}
// ToStringMapStringE casts an empty interface to a map[string]string.
func ToStringMapStringE(i interface{}) (map[string]string, error) {
jww.DEBUG.Println("ToStringMapStringE called on type:", reflect.TypeOf(i))
var m = map[string]string{}
switch v := i.(type) {
case map[string]string:
return v, nil
case map[string]interface{}:
for k, val := range v {
m[ToString(k)] = ToString(val)
}
return m, nil
case map[interface{}]string:
for k, val := range v {
m[ToString(k)] = ToString(val)
}
return m, nil
case map[interface{}]interface{}:
for k, val := range v {
m[ToString(k)] = ToString(val)
}
return m, nil
default:
return m, fmt.Errorf("Unable to Cast %#v to map[string]string", i)
}
}
// ToStringMapStringSliceE casts an empty interface to a map[string][]string.
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func ToStringMapStringSliceE(i interface{}) (map[string][]string, error) {
jww.DEBUG.Println("ToStringMapStringSliceE called on type:", reflect.TypeOf(i))
var m = map[string][]string{}
switch v := i.(type) {
case map[string][]string:
return v, nil
case map[string][]interface{}:
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for k, val := range v {
m[ToString(k)] = ToStringSlice(val)
}
return m, nil
case map[string]string:
for k, val := range v {
m[ToString(k)] = []string{val}
}
case map[string]interface{}:
for k, val := range v {
m[ToString(k)] = []string{ToString(val)}
}
return m, nil
case map[interface{}][]string:
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for k, val := range v {
m[ToString(k)] = ToStringSlice(val)
}
return m, nil
case map[interface{}]string:
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for k, val := range v {
m[ToString(k)] = ToStringSlice(val)
}
return m, nil
case map[interface{}][]interface{}:
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for k, val := range v {
m[ToString(k)] = ToStringSlice(val)
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}
return m, nil
case map[interface{}]interface{}:
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for k, val := range v {
key, err := ToStringE(k)
if err != nil {
return m, fmt.Errorf("Unable to Cast %#v to map[string][]string", i)
}
value, err := ToStringSliceE(val)
if err != nil {
return m, fmt.Errorf("Unable to Cast %#v to map[string][]string", i)
}
m[key] = value
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}
default:
return m, fmt.Errorf("Unable to Cast %#v to map[string][]string", i)
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}
return m, nil
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}
// ToStringMapBoolE casts an empty interface to a map[string]bool.
func ToStringMapBoolE(i interface{}) (map[string]bool, error) {
jww.DEBUG.Println("ToStringMapBoolE called on type:", reflect.TypeOf(i))
var m = map[string]bool{}
switch v := i.(type) {
case map[interface{}]interface{}:
for k, val := range v {
m[ToString(k)] = ToBool(val)
}
return m, nil
case map[string]interface{}:
for k, val := range v {
m[ToString(k)] = ToBool(val)
}
return m, nil
case map[string]bool:
return v, nil
default:
return m, fmt.Errorf("Unable to Cast %#v to map[string]bool", i)
}
}
// ToStringMapE casts an empty interface to a map[string]interface{}.
func ToStringMapE(i interface{}) (map[string]interface{}, error) {
jww.DEBUG.Println("ToStringMapE called on type:", reflect.TypeOf(i))
var m = map[string]interface{}{}
switch v := i.(type) {
case map[interface{}]interface{}:
for k, val := range v {
m[ToString(k)] = val
}
return m, nil
case map[string]interface{}:
return v, nil
default:
return m, fmt.Errorf("Unable to Cast %#v to map[string]interface{}", i)
}
}
// ToSliceE casts an empty interface to a []interface{}.
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func ToSliceE(i interface{}) ([]interface{}, error) {
jww.DEBUG.Println("ToSliceE called on type:", reflect.TypeOf(i))
var s []interface{}
switch v := i.(type) {
case []interface{}:
for _, u := range v {
s = append(s, u)
}
return s, nil
case []map[string]interface{}:
for _, u := range v {
s = append(s, u)
}
return s, nil
default:
return s, fmt.Errorf("Unable to Cast %#v of type %v to []interface{}", i, reflect.TypeOf(i))
}
}
// ToStringSliceE casts an empty interface to a []string.
func ToStringSliceE(i interface{}) ([]string, error) {
jww.DEBUG.Println("ToStringSliceE called on type:", reflect.TypeOf(i))
var a []string
switch v := i.(type) {
case []interface{}:
for _, u := range v {
a = append(a, ToString(u))
}
return a, nil
case []string:
return v, nil
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case string:
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return strings.Fields(v), nil
case interface{}:
str, err := ToStringE(v)
if err != nil {
return a, fmt.Errorf("Unable to Cast %#v to []string", i)
}
return []string{str}, nil
default:
return a, fmt.Errorf("Unable to Cast %#v to []string", i)
}
}
// ToIntSliceE casts an empty interface to a []int.
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func ToIntSliceE(i interface{}) ([]int, error) {
jww.DEBUG.Println("ToIntSliceE called on type:", reflect.TypeOf(i))
if i == nil {
return []int{}, fmt.Errorf("Unable to Cast %#v to []int", i)
}
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switch v := i.(type) {
case []int:
return v, nil
}
kind := reflect.TypeOf(i).Kind()
switch kind {
case reflect.Slice, reflect.Array:
s := reflect.ValueOf(i)
a := make([]int, s.Len())
for j := 0; j < s.Len(); j++ {
val, err := ToIntE(s.Index(j).Interface())
if err != nil {
return []int{}, fmt.Errorf("Unable to Cast %#v to []int", i)
}
a[j] = val
}
return a, nil
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default:
return []int{}, fmt.Errorf("Unable to Cast %#v to []int", i)
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}
}
// StringToDate casts an empty interface to a time.Time.
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func StringToDate(s string) (time.Time, error) {
return parseDateWith(s, []string{
time.RFC3339,
"2006-01-02T15:04:05", // iso8601 without timezone
time.RFC1123Z,
time.RFC1123,
time.RFC822Z,
time.RFC822,
time.ANSIC,
time.UnixDate,
time.RubyDate,
"2006-01-02 15:04:05Z07:00",
"02 Jan 06 15:04 MST",
"2006-01-02",
"02 Jan 2006",
"2006-01-02 15:04:05 -07:00",
"2006-01-02 15:04:05 -0700",
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})
}
func parseDateWith(s string, dates []string) (d time.Time, e error) {
for _, dateType := range dates {
if d, e = time.Parse(dateType, s); e == nil {
return
}
}
return d, fmt.Errorf("Unable to parse date: %s", s)
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}