Golang StructValue.FieldByIndex方法代码示例

// unmarshalPaths walks down an XML structure looking for
// wanted paths, and calls unmarshal on them.
func (p *Parser) unmarshalPaths(sv *reflect.StructValue, paths map[string]pathInfo, path string, start *StartElement) os.Error {
	if info, _ := paths[path]; info.complete {
		return p.unmarshal(sv.FieldByIndex(info.fieldIdx), start)
	}
	for {
		tok, err := p.Token()
		if err != nil {
			return err
		}
		switch t := tok.(type) {
		case StartElement:
			k := path + ">" + fieldName(t.Name.Local)
			if _, found := paths[k]; found {
				if err := p.unmarshalPaths(sv, paths, k, &t); err != nil {
					return err
				}
				continue
			}
			if err := p.Skip(); err != nil {
				return err
			}
		case EndElement:
			return nil
		}
	}
	panic("unreachable")
}

func (e *encodeState) writeStruct(v *reflect.StructValue) {
	offset := e.beginDoc()
	for name, f := range compileStruct(v.Type().(*reflect.StructType)) {
		e.encodeValue(name, v.FieldByIndex(f.Index))
	}
	e.WriteByte(0)
	e.endDoc(offset)
}

//.........这里部分代码省略.........
		if _, ok := v.Interface().(Name); ok {
			v.Set(reflect.NewValue(start.Name).(*reflect.StructValue))
			break
		}

		sv = v
		typ := sv.Type().(*reflect.StructType)
		styp = typ
		// Assign name.
		if f, ok := typ.FieldByName("XMLName"); ok {
			// Validate element name.
			if f.Tag != "" {
				tag := f.Tag
				ns := ""
				i := strings.LastIndex(tag, " ")
				if i >= 0 {
					ns, tag = tag[0:i], tag[i+1:]
				}
				if tag != start.Name.Local {
					return UnmarshalError("expected element type <" + tag + "> but have <" + start.Name.Local + ">")
				}
				if ns != "" && ns != start.Name.Space {
					e := "expected element <" + tag + "> in name space " + ns + " but have "
					if start.Name.Space == "" {
						e += "no name space"
					} else {
						e += start.Name.Space
					}
					return UnmarshalError(e)
				}
			}

			// Save
			v := sv.FieldByIndex(f.Index)
			if _, ok := v.Interface().(Name); !ok {
				return UnmarshalError(sv.Type().String() + " field XMLName does not have type xml.Name")
			}
			v.(*reflect.StructValue).Set(reflect.NewValue(start.Name).(*reflect.StructValue))
		}

		// Assign attributes.
		// Also, determine whether we need to save character data or comments.
		for i, n := 0, typ.NumField(); i < n; i++ {
			f := typ.Field(i)
			switch f.Tag {
			case "attr":
				strv, ok := sv.FieldByIndex(f.Index).(*reflect.StringValue)
				if !ok {
					return UnmarshalError(sv.Type().String() + " field " + f.Name + " has attr tag but is not type string")
				}
				// Look for attribute.
				val := ""
				k := strings.ToLower(f.Name)
				for _, a := range start.Attr {
					if fieldName(a.Name.Local) == k {
						val = a.Value
						break
					}
				}
				strv.Set(val)

			case "comment":
				if saveComment == nil {
					saveComment = sv.FieldByIndex(f.Index)
				}

//.........这里部分代码省略.........
			break
		}
		mv = v
		if mv.IsNil() {
			mv.SetValue(reflect.MakeMap(t))
		}
	case *reflect.StructValue:
		sv = v
	default:
		d.saveError(&UnmarshalTypeError{"object", v.Type()})
	}

	if mv == nil && sv == nil {
		d.off--
		d.next() // skip over { } in input
		return
	}

	for {
		// Read opening " of string key or closing }.
		op := d.scanWhile(scanSkipSpace)
		if op == scanEndObject {
			// closing } - can only happen on first iteration.
			break
		}
		if op != scanBeginLiteral {
			d.error(errPhase)
		}

		// Read string key.
		start := d.off - 1
		op = d.scanWhile(scanContinue)
		item := d.data[start : d.off-1]
		key, ok := unquote(item)
		if !ok {
			d.error(errPhase)
		}

		// Figure out field corresponding to key.
		var subv reflect.Value
		if mv != nil {
			subv = reflect.MakeZero(mv.Type().(*reflect.MapType).Elem())
		} else {
			var f reflect.StructField
			var ok bool
			// First try for field with that tag.
			st := sv.Type().(*reflect.StructType)
			for i := 0; i < sv.NumField(); i++ {
				f = st.Field(i)
				if f.Tag == key {
					ok = true
					break
				}
			}
			if !ok {
				// Second, exact match.
				f, ok = st.FieldByName(key)
			}
			if !ok {
				// Third, case-insensitive match.
				f, ok = st.FieldByNameFunc(func(s string) bool { return matchName(key, s) })
			}

			// Extract value; name must be exported.
			if ok {
				if f.PkgPath != "" {
					d.saveError(&UnmarshalFieldError{key, st, f})
				} else {
					subv = sv.FieldByIndex(f.Index)
				}
			}
		}

		// Read : before value.
		if op == scanSkipSpace {
			op = d.scanWhile(scanSkipSpace)
		}
		if op != scanObjectKey {
			d.error(errPhase)
		}

		// Read value.
		d.value(subv)

		// Write value back to map;
		// if using struct, subv points into struct already.
		if mv != nil {
			mv.SetElem(reflect.NewValue(key), subv)
		}

		// Next token must be , or }.
		op = d.scanWhile(scanSkipSpace)
		if op == scanEndObject {
			break
		}
		if op != scanObjectValue {
			d.error(errPhase)
		}
	}
}

//.........这里部分代码省略.........
		if _, ok := v.Interface().(Name); ok {
			v.Set(reflect.NewValue(start.Name).(*reflect.StructValue))
			break
		}

		sv = v
		typ := sv.Type().(*reflect.StructType)
		styp = typ
		// Assign name.
		if f, ok := typ.FieldByName("XMLName"); ok {
			// Validate element name.
			if f.Tag != "" {
				tag := f.Tag
				ns := ""
				i := strings.LastIndex(tag, " ")
				if i >= 0 {
					ns, tag = tag[0:i], tag[i+1:]
				}
				if tag != start.Name.Local {
					return UnmarshalError("expected element type <" + tag + "> but have <" + start.Name.Local + ">")
				}
				if ns != "" && ns != start.Name.Space {
					e := "expected element <" + tag + "> in name space " + ns + " but have "
					if start.Name.Space == "" {
						e += "no name space"
					} else {
						e += start.Name.Space
					}
					return UnmarshalError(e)
				}
			}

			// Save
			v := sv.FieldByIndex(f.Index)
			if _, ok := v.Interface().(Name); !ok {
				return UnmarshalError(sv.Type().String() + " field XMLName does not have type xml.Name")
			}
			v.(*reflect.StructValue).Set(reflect.NewValue(start.Name).(*reflect.StructValue))
		}

		// Assign attributes.
		// Also, determine whether we need to save character data or comments.
		for i, n := 0, typ.NumField(); i < n; i++ {
			f := typ.Field(i)
			switch f.Tag {
			case "attr":
				strv, ok := sv.FieldByIndex(f.Index).(*reflect.StringValue)
				if !ok {
					return UnmarshalError(sv.Type().String() + " field " + f.Name + " has attr tag but is not type string")
				}
				// Look for attribute.
				val := ""
				k := strings.ToLower(f.Name)
				for _, a := range start.Attr {
					if fieldName(a.Name.Local) == k {
						val = a.Value
						break
					}
				}
				strv.Set(val)

			case "comment":
				if saveComment == nil {
					saveComment = sv.FieldByIndex(f.Index)
				}