141 lines
3.8 KiB
Go
141 lines
3.8 KiB
Go
package structs
|
|
|
|
import (
|
|
"errors"
|
|
"fmt"
|
|
"reflect"
|
|
)
|
|
|
|
var (
|
|
errNotExported = errors.New("field is not exported")
|
|
errNotSettable = errors.New("field is not settable")
|
|
)
|
|
|
|
// Field represents a single struct field that encapsulates high level
|
|
// functions around the field.
|
|
type Field struct {
|
|
value reflect.Value
|
|
field reflect.StructField
|
|
defaultTag string
|
|
}
|
|
|
|
// Tag returns the value associated with key in the tag string. If there is no
|
|
// such key in the tag, Tag returns the empty string.
|
|
func (f *Field) Tag(key string) string {
|
|
return f.field.Tag.Get(key)
|
|
}
|
|
|
|
// Value returns the underlying value of the field. It panics if the field
|
|
// is not exported.
|
|
func (f *Field) Value() interface{} {
|
|
return f.value.Interface()
|
|
}
|
|
|
|
// IsEmbedded returns true if the given field is an anonymous field (embedded)
|
|
func (f *Field) IsEmbedded() bool {
|
|
return f.field.Anonymous
|
|
}
|
|
|
|
// IsExported returns true if the given field is exported.
|
|
func (f *Field) IsExported() bool {
|
|
return f.field.PkgPath == ""
|
|
}
|
|
|
|
// IsZero returns true if the given field is not initialized (has a zero value).
|
|
// It panics if the field is not exported.
|
|
func (f *Field) IsZero() bool {
|
|
zero := reflect.Zero(f.value.Type()).Interface()
|
|
current := f.Value()
|
|
|
|
return reflect.DeepEqual(current, zero)
|
|
}
|
|
|
|
// Name returns the name of the given field
|
|
func (f *Field) Name() string {
|
|
return f.field.Name
|
|
}
|
|
|
|
// Kind returns the fields kind, such as "string", "map", "bool", etc ..
|
|
func (f *Field) Kind() reflect.Kind {
|
|
return f.value.Kind()
|
|
}
|
|
|
|
// Set sets the field to given value v. It returns an error if the field is not
|
|
// settable (not addressable or not exported) or if the given value's type
|
|
// doesn't match the fields type.
|
|
func (f *Field) Set(val interface{}) error {
|
|
// we can't set unexported fields, so be sure this field is exported
|
|
if !f.IsExported() {
|
|
return errNotExported
|
|
}
|
|
|
|
// do we get here? not sure...
|
|
if !f.value.CanSet() {
|
|
return errNotSettable
|
|
}
|
|
|
|
given := reflect.ValueOf(val)
|
|
|
|
if f.value.Kind() != given.Kind() {
|
|
return fmt.Errorf("wrong kind. got: %s want: %s", given.Kind(), f.value.Kind())
|
|
}
|
|
|
|
f.value.Set(given)
|
|
return nil
|
|
}
|
|
|
|
// Zero sets the field to its zero value. It returns an error if the field is not
|
|
// settable (not addressable or not exported).
|
|
func (f *Field) Zero() error {
|
|
zero := reflect.Zero(f.value.Type()).Interface()
|
|
return f.Set(zero)
|
|
}
|
|
|
|
// Fields returns a slice of Fields. This is particular handy to get the fields
|
|
// of a nested struct . A struct tag with the content of "-" ignores the
|
|
// checking of that particular field. Example:
|
|
//
|
|
// // Field is ignored by this package.
|
|
// Field *http.Request `structs:"-"`
|
|
//
|
|
// It panics if field is not exported or if field's kind is not struct
|
|
func (f *Field) Fields() []*Field {
|
|
return getFields(f.value, f.defaultTag)
|
|
}
|
|
|
|
// Field returns the field from a nested struct. It panics if the nested struct
|
|
// is not exported or if the field was not found.
|
|
func (f *Field) Field(name string) *Field {
|
|
field, ok := f.FieldOk(name)
|
|
if !ok {
|
|
panic("field not found")
|
|
}
|
|
|
|
return field
|
|
}
|
|
|
|
// FieldOk returns the field from a nested struct. The boolean returns whether
|
|
// the field was found (true) or not (false).
|
|
func (f *Field) FieldOk(name string) (*Field, bool) {
|
|
value := &f.value
|
|
// value must be settable so we need to make sure it holds the address of the
|
|
// variable and not a copy, so we can pass the pointer to strctVal instead of a
|
|
// copy (which is not assigned to any variable, hence not settable).
|
|
// see "https://blog.golang.org/laws-of-reflection#TOC_8."
|
|
if f.value.Kind() != reflect.Ptr {
|
|
a := f.value.Addr()
|
|
value = &a
|
|
}
|
|
v := strctVal(value.Interface())
|
|
t := v.Type()
|
|
|
|
field, ok := t.FieldByName(name)
|
|
if !ok {
|
|
return nil, false
|
|
}
|
|
|
|
return &Field{
|
|
field: field,
|
|
value: v.FieldByName(name),
|
|
}, true
|
|
}
|