consul/vendor/github.com/mitchellh/pointerstructure/set.go

123 lines
3.1 KiB
Go

package pointerstructure
import (
"fmt"
"reflect"
)
// Set writes a value v to the pointer p in structure s.
//
// The structures s must have non-zero values set up to this pointer.
// For example, if setting "/bob/0/name", then "/bob/0" must be set already.
//
// The returned value is potentially a new value if this pointer represents
// the root document. Otherwise, the returned value will always be s.
func (p *Pointer) Set(s, v interface{}) (interface{}, error) {
// if we represent the root doc, return that
if len(p.Parts) == 0 {
return v, nil
}
// Save the original since this is going to be our return value
originalS := s
// Get the parent value
var err error
s, err = p.Parent().Get(s)
if err != nil {
return nil, err
}
// Map for lookup of getter to call for type
funcMap := map[reflect.Kind]setFunc{
reflect.Array: p.setSlice,
reflect.Map: p.setMap,
reflect.Slice: p.setSlice,
}
val := reflect.ValueOf(s)
for val.Kind() == reflect.Interface {
val = val.Elem()
}
for val.Kind() == reflect.Ptr {
val = reflect.Indirect(val)
}
f, ok := funcMap[val.Kind()]
if !ok {
return nil, fmt.Errorf("set %s: invalid value kind: %s", p, val.Kind())
}
result, err := f(originalS, val, reflect.ValueOf(v))
if err != nil {
return nil, fmt.Errorf("set %s: %s", p, err)
}
return result, nil
}
type setFunc func(interface{}, reflect.Value, reflect.Value) (interface{}, error)
func (p *Pointer) setMap(root interface{}, m, value reflect.Value) (interface{}, error) {
part := p.Parts[len(p.Parts)-1]
key, err := coerce(reflect.ValueOf(part), m.Type().Key())
if err != nil {
return root, err
}
elem, err := coerce(value, m.Type().Elem())
if err != nil {
return root, err
}
// Set the key
m.SetMapIndex(key, elem)
return root, nil
}
func (p *Pointer) setSlice(root interface{}, s, value reflect.Value) (interface{}, error) {
// Coerce the value, we'll need that no matter what
value, err := coerce(value, s.Type().Elem())
if err != nil {
return root, err
}
// If the part is the special "-", that means to append it (RFC6901 4.)
part := p.Parts[len(p.Parts)-1]
if part == "-" {
return p.setSliceAppend(root, s, value)
}
// Coerce the key to an int
idxVal, err := coerce(reflect.ValueOf(part), reflect.TypeOf(42))
if err != nil {
return root, err
}
idx := int(idxVal.Int())
// Verify we're within bounds
if idx < 0 || idx >= s.Len() {
return root, fmt.Errorf(
"index %d is out of range (length = %d)", idx, s.Len())
}
// Set the key
s.Index(idx).Set(value)
return root, nil
}
func (p *Pointer) setSliceAppend(root interface{}, s, value reflect.Value) (interface{}, error) {
// Coerce the value, we'll need that no matter what. This should
// be a no-op since we expect it to be done already, but there is
// a fast-path check for that in coerce so do it anyways.
value, err := coerce(value, s.Type().Elem())
if err != nil {
return root, err
}
// We can assume "s" is the parent of pointer value. We need to actually
// write s back because Append can return a new slice.
return p.Parent().Set(root, reflect.Append(s, value).Interface())
}