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tag.go
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tag.go
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package googp
import (
"reflect"
"strings"
)
const (
structTagKey = "googp"
)
// tag is struct tag supported by googp
type tag struct {
// Array of OGP property names. (e.g. `og:title`)
names []string
}
// newTag is create a `*tag` from `reflect.StructField`
func newTag(f reflect.StructField) *tag {
value := f.Tag.Get(structTagKey)
var names []string
switch value {
case "-":
names = []string{}
case "":
if f.Anonymous {
names = []string{""}
} else {
// NOTE: If tag is not specified, it is same as being given `og:${field_name}`.
names = []string{"og:" + toSnake(f.Name)}
}
default:
names = strings.Split(value, ",")
}
return &tag{names: names}
}
// isContainsName returns true, when the tag contains the name.
// Otherwise, it returns false.
func (t *tag) isContainsName(name string) bool {
for _, n := range t.names {
if n == name {
return true
}
}
return false
}
// toSnake converts the string into a snake case.
func toSnake(str string) string {
runes := []rune(str)
var p int
for i := 0; i < len(runes); i++ {
c := runes[i]
if c >= 'A' && c <= 'Z' {
runes[i] = c - ('A' - 'a')
if p+1 < i {
tmp := append([]rune{'_'}, runes[i:]...)
runes = append(runes[0:i], tmp...)
}
p = i
}
}
return string(runes)
}