| // Copyright 2017 syzkaller project authors. All rights reserved. |
| // Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file. |
| |
| package serializer |
| |
| import ( |
| "reflect" |
| |
| "fmt" |
| "io" |
| ) |
| |
| // Write writes Go-syntax representation of v into w. |
| // This is similar to fmt.Fprintf(w, "%#v", v), but properly handles pointers, |
| // does not write package names before types, omits struct fields with default values, |
| // omits type names where possible, etc. On the other hand, it currently does not |
| // support all types (e.g. channels and maps). |
| func Write(ww io.Writer, i interface{}) { |
| w := writer{ww} |
| v := reflect.ValueOf(i) |
| if v.Kind() == reflect.Slice && (v.IsNil() || v.Len() == 0) { |
| w.typ(v.Type()) |
| w.string("(nil)") |
| return |
| } |
| w.do(v, false) |
| } |
| |
| type writer struct { |
| w io.Writer |
| } |
| |
| func (w *writer) do(v reflect.Value, sliceElem bool) { |
| switch v.Kind() { |
| case reflect.Ptr: |
| w.doPtr(v, sliceElem) |
| case reflect.Interface: |
| if v.IsNil() { |
| w.string("nil") |
| } else { |
| w.do(v.Elem(), false) |
| } |
| case reflect.Slice: |
| w.doSlice(v) |
| case reflect.Struct: |
| w.doStruct(v, sliceElem) |
| case reflect.Bool: |
| if v.Bool() { |
| w.string("true") |
| } else { |
| w.string("false") |
| } |
| case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64: |
| fmt.Fprintf(w.w, "%v", v.Int()) |
| case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr: |
| fmt.Fprintf(w.w, "%v", v.Uint()) |
| case reflect.String: |
| fmt.Fprintf(w.w, "%q", v.String()) |
| case reflect.Func: |
| // Skip, no way to serialize this. |
| default: |
| panic(fmt.Sprintf("unsupported type: %#v", v.Type().String())) |
| } |
| } |
| |
| func (w *writer) doPtr(v reflect.Value, sliceElem bool) { |
| if v.IsNil() { |
| w.string("nil") |
| return |
| } |
| if !sliceElem { |
| w.byte('&') |
| } |
| if v.Elem().Kind() != reflect.Struct { |
| panic(fmt.Sprintf("only pointers to structs are supported, got %v", |
| v.Type().Name())) |
| } |
| w.do(v.Elem(), sliceElem) |
| } |
| |
| func (w *writer) doSlice(v reflect.Value) { |
| if v.IsNil() || v.Len() == 0 { |
| w.string("nil") |
| return |
| } |
| w.typ(v.Type()) |
| sub := v.Type().Elem().Kind() |
| if sub == reflect.Ptr || sub == reflect.Interface || sub == reflect.Struct { |
| // Elem per-line. |
| w.string("{\n") |
| for i := 0; i < v.Len(); i++ { |
| w.do(v.Index(i), true) |
| w.string(",\n") |
| } |
| w.byte('}') |
| return |
| } |
| // All on one line. |
| w.byte('{') |
| for i := 0; i < v.Len(); i++ { |
| if i > 0 { |
| w.byte(',') |
| } |
| w.do(v.Index(i), true) |
| } |
| w.byte('}') |
| } |
| |
| func (w *writer) doStruct(v reflect.Value, sliceElem bool) { |
| if !sliceElem { |
| w.string(v.Type().Name()) |
| } |
| w.byte('{') |
| needComma := false |
| for i := 0; i < v.NumField(); i++ { |
| f := v.Field(i) |
| if isDefaultValue(f) { |
| continue |
| } |
| if needComma { |
| w.byte(',') |
| } |
| w.string(v.Type().Field(i).Name) |
| w.byte(':') |
| w.do(f, false) |
| needComma = true |
| } |
| w.byte('}') |
| } |
| |
| func (w *writer) typ(t reflect.Type) { |
| switch t.Kind() { |
| case reflect.Ptr: |
| w.byte('*') |
| w.typ(t.Elem()) |
| case reflect.Slice: |
| w.string("[]") |
| w.typ(t.Elem()) |
| default: |
| w.string(t.Name()) |
| } |
| } |
| |
| func (w *writer) string(v string) { |
| io.WriteString(w.w, v) |
| } |
| |
| func (w *writer) byte(v byte) { |
| if bw, ok := w.w.(io.ByteWriter); ok { |
| bw.WriteByte(v) |
| } else { |
| w.w.Write([]byte{v}) |
| } |
| } |
| |
| func isDefaultValue(v reflect.Value) bool { |
| switch v.Kind() { |
| case reflect.Ptr: |
| return v.IsNil() |
| case reflect.Interface: |
| return v.IsNil() |
| case reflect.Slice: |
| return v.IsNil() || v.Len() == 0 |
| case reflect.Struct: |
| for i := 0; i < v.NumField(); i++ { |
| if !isDefaultValue(v.Field(i)) { |
| return false |
| } |
| } |
| return true |
| case reflect.Bool: |
| return !v.Bool() |
| case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64: |
| return v.Int() == 0 |
| case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr: |
| return v.Uint() == 0 |
| case reflect.String: |
| return v.String() == "" |
| case reflect.Func: |
| return true |
| default: |
| return false |
| } |
| } |