gotosocial/vendor/codeberg.org/gruf/go-mangler/load.go
kim 51c156cca1
pull in latest go-kv, go-cache (#1530)
Signed-off-by: kim <grufwub@gmail.com>
2023-02-19 10:36:38 +01:00

333 lines
7.3 KiB
Go

package mangler
import (
"reflect"
)
// loadMangler is the top-most Mangler load function. It guarantees that a Mangler
// function will be returned for given value interface{} and reflected type. Else panics.
func loadMangler(a any, t reflect.Type) Mangler {
// Load mangler function
mng, rmng := load(a, t)
if mng != nil {
// Use preferred mangler.
return mng
}
if rmng != nil {
// Wrap reflect mangler to handle iface
return func(buf []byte, a any) []byte {
return rmng(buf, reflect.ValueOf(a))
}
}
// No mangler function could be determined
panic("cannot mangle type: " + t.String())
}
// load will load a Mangler or reflect Mangler for given type and iface 'a'.
// Note: allocates new interface value if nil provided, i.e. if coming via reflection.
func load(a any, t reflect.Type) (Mangler, rMangler) {
if t == nil {
// There is no reflect type to search by
panic("cannot mangle nil interface{} type")
}
if a == nil {
// Alloc new iface instance
v := reflect.New(t).Elem()
a = v.Interface()
}
// Check for Mangled implementation.
if _, ok := a.(Mangled); ok {
return mangle_mangled, nil
}
// Search mangler by reflection.
mng, rmng := loadReflect(t)
if mng != nil {
return mng, nil
}
// Prefer iface mangler, else, reflected.
return loadIface(a), rmng
}
// loadIface is used as a near-last-resort interface{} type switch
// loader for types implementating other known (slower) functions.
func loadIface(a any) Mangler {
switch a.(type) {
case binarymarshaler:
return mangle_binary
case stringer:
return mangle_stringer
case textmarshaler:
return mangle_text
case jsonmarshaler:
return mangle_json
default:
return nil
}
}
// loadReflect will load a Mangler (or rMangler) function for the given reflected type info.
// NOTE: this is used as the top level load function for nested reflective searches.
func loadReflect(t reflect.Type) (Mangler, rMangler) {
switch t.Kind() {
case reflect.Pointer:
return loadReflectPtr(t.Elem())
case reflect.String:
return mangle_string, nil
case reflect.Array:
return nil, loadReflectArray(t.Elem())
case reflect.Slice:
// Element type
et := t.Elem()
// Preferably look for known slice mangler func
if mng := loadReflectKnownSlice(et); mng != nil {
return mng, nil
}
// Else handle as array elements
return nil, loadReflectArray(et)
case reflect.Map:
return nil, loadReflectMap(t.Key(), t.Elem())
case reflect.Bool:
return mangle_bool, nil
case reflect.Int,
reflect.Uint,
reflect.Uintptr:
return mangle_platform_int, nil
case reflect.Int8, reflect.Uint8:
return mangle_8bit, nil
case reflect.Int16, reflect.Uint16:
return mangle_16bit, nil
case reflect.Int32, reflect.Uint32:
return mangle_32bit, nil
case reflect.Int64, reflect.Uint64:
return mangle_64bit, nil
case reflect.Float32:
return mangle_32bit, nil
case reflect.Float64:
return mangle_64bit, nil
case reflect.Complex64:
return mangle_64bit, nil
case reflect.Complex128:
return mangle_128bit, nil
default:
return nil, nil
}
}
// loadReflectPtr loads a Mangler (or rMangler) function for a ptr's element type.
// This also handles further dereferencing of any further ptr indrections (e.g. ***int).
func loadReflectPtr(et reflect.Type) (Mangler, rMangler) {
count := 1
// Iteratively dereference ptrs
for et.Kind() == reflect.Pointer {
et = et.Elem()
count++
}
if et.Kind() == reflect.Array {
// Array elem type
at := et.Elem()
// Special case of addressable (sliceable) array
if mng := loadReflectKnownSlice(at); mng != nil {
rmng := array_to_slice_mangler(mng)
return nil, deref_ptr_rmangler(rmng, count)
}
// Look for an array mangler function, this will
// access elements by index using reflect.Value and
// pass each one to a separate mangler function.
if rmng := loadReflectArray(at); rmng != nil {
return nil, deref_ptr_rmangler(rmng, count)
}
return nil, nil
}
// Try remove a layer of derefs by loading a mangler
// for a known ptr kind. The less reflection the better!
if mng := loadReflectKnownPtr(et); mng != nil {
if count == 1 {
return mng, nil
}
return nil, deref_ptr_mangler(mng, count-1)
}
// Search for ptr elemn type mangler
if mng, rmng := load(nil, et); mng != nil {
return nil, deref_ptr_mangler(mng, count)
} else if rmng != nil {
return nil, deref_ptr_rmangler(rmng, count)
}
return nil, nil
}
// loadReflectKnownPtr loads a Mangler function for a known ptr-of-element type (in this case, primtive ptrs).
func loadReflectKnownPtr(et reflect.Type) Mangler {
switch et.Kind() {
case reflect.String:
return mangle_string_ptr
case reflect.Bool:
return mangle_bool_ptr
case reflect.Int,
reflect.Uint,
reflect.Uintptr:
return mangle_platform_int_ptr
case reflect.Int8, reflect.Uint8:
return mangle_8bit_ptr
case reflect.Int16, reflect.Uint16:
return mangle_16bit_ptr
case reflect.Int32, reflect.Uint32:
return mangle_32bit_ptr
case reflect.Int64, reflect.Uint64:
return mangle_64bit_ptr
case reflect.Float32:
return mangle_32bit_ptr
case reflect.Float64:
return mangle_64bit_ptr
case reflect.Complex64:
return mangle_64bit_ptr
case reflect.Complex128:
return mangle_128bit_ptr
default:
return nil
}
}
// loadReflectKnownSlice loads a Mangler function for a known slice-of-element type (in this case, primtives).
func loadReflectKnownSlice(et reflect.Type) Mangler {
switch et.Kind() {
case reflect.String:
return mangle_string_slice
case reflect.Bool:
return mangle_bool_slice
case reflect.Int,
reflect.Uint,
reflect.Uintptr:
return mangle_platform_int_slice
case reflect.Int8, reflect.Uint8:
return mangle_8bit_slice
case reflect.Int16, reflect.Uint16:
return mangle_16bit_slice
case reflect.Int32, reflect.Uint32:
return mangle_32bit_slice
case reflect.Int64, reflect.Uint64:
return mangle_64bit_slice
case reflect.Float32:
return mangle_32bit_slice
case reflect.Float64:
return mangle_64bit_slice
case reflect.Complex64:
return mangle_64bit_slice
case reflect.Complex128:
return mangle_128bit_slice
default:
return nil
}
}
// loadReflectArray loads an rMangler function for an array (or slice) or given element type.
func loadReflectArray(et reflect.Type) rMangler {
// Search via reflected array element type
if mng, rmng := load(nil, et); mng != nil {
return iter_array_mangler(mng)
} else if rmng != nil {
return iter_array_rmangler(rmng)
}
return nil
}
// loadReflectMap loads an rMangler function for a map of given key and value types.
func loadReflectMap(kt, vt reflect.Type) rMangler {
var kmng, vmng rMangler
// Search for mangler for key type
mng, rmng := load(nil, kt)
switch {
// Wrap key mangler to reflect
case mng != nil:
mng := mng // take our own ptr
kmng = func(buf []byte, v reflect.Value) []byte {
return mng(buf, v.Interface())
}
// Use reflect key mangler as-is
case rmng != nil:
kmng = rmng
// No mangler found
default:
return nil
}
// Search for mangler for value type
mng, rmng = load(nil, vt)
switch {
// Wrap value mangler to reflect
case mng != nil:
mng := mng // take our own ptr
vmng = func(buf []byte, v reflect.Value) []byte {
return mng(buf, v.Interface())
}
// Use reflect value mangler as-is
case rmng != nil:
vmng = rmng
// No mangler found
default:
return nil
}
// Wrap key/value manglers in map iter
return iter_map_rmangler(kmng, vmng)
}