// StructPtr generates pointers to a given struct type.
// rt has to be the reflect type of the struct, gens contains a map of field generators.
// Note that the result types of the generators in gen have to match the type of the correspoinding
// field in the struct. Also note that only public fields of a struct can be generated
func StructPtr(rt reflect.Type, gens map[string]gopter.Gen) gopter.Gen {
if rt.Kind() == reflect.Ptr {
rt = rt.Elem()
}
if rt.Kind() != reflect.Struct {
return Fail(rt)
}
return func(genParams *gopter.GenParameters) *gopter.GenResult {
result := reflect.New(rt)
for name, gen := range gens {
field, ok := rt.FieldByName(name)
if !ok {
continue
}
value, ok := gen(genParams).Retrieve()
if !ok {
return gopter.NewEmptyResult(rt)
}
result.Elem().FieldByIndex(field.Index).Set(reflect.ValueOf(value))
}
return gopter.NewGenResult(result.Interface(), gopter.NoShrinker)
}
}
// PtrOf generates a pointer to a generated element
func PtrOf(elementGen gopter.Gen) gopter.Gen {
return func(genParams *gopter.GenParameters) *gopter.GenResult {
element := elementGen(genParams)
elementShrinker := element.Shrinker
elementSieve := element.Sieve
value, ok := element.Retrieve()
if !ok || genParams.NextBool() {
result := gopter.NewEmptyResult(reflect.PtrTo(element.ResultType))
result.Sieve = func(v interface{}) bool {
return v == nil || elementSieve == nil || elementSieve(reflect.ValueOf(v).Elem().Interface())
}
return result
}
// To get the right pointer type we have to create a slice with one element
slice := reflect.MakeSlice(reflect.SliceOf(element.ResultType), 0, 1)
slice = reflect.Append(slice, reflect.ValueOf(value))
result := gopter.NewGenResult(slice.Index(0).Addr().Interface(), PtrShrinker(elementShrinker))
result.Sieve = func(v interface{}) bool {
return v == nil || elementSieve == nil || elementSieve(reflect.ValueOf(v).Elem().Interface())
}
return result
}
}
// Fail is a generator that always fails to generate a value
// Useful as fallback
func Fail(resultType reflect.Type) gopter.Gen {
return func(*gopter.GenParameters) *gopter.GenResult {
return gopter.NewEmptyResult(resultType)
}
}