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