065e07da4b
for convenience. Signed-off-by: Izuru Yakumo <yakumo.izuru@chaotic.ninja> git-svn-id: file:///srv/svn/repo/suika/trunk@822 f0ae65fe-ee39-954e-97ec-027ff2717ef4
77 lines
1.9 KiB
Go
77 lines
1.9 KiB
Go
package bare
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import (
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"fmt"
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"reflect"
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)
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// Any type which is a union member must implement this interface. You must
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// also call RegisterUnion for go-bare to marshal or unmarshal messages which
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// utilize your union type.
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type Union interface {
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IsUnion()
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}
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type UnionTags struct {
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iface reflect.Type
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tags map[reflect.Type]uint64
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types map[uint64]reflect.Type
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}
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var unionInterface = reflect.TypeOf((*Union)(nil)).Elem()
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var unionRegistry map[reflect.Type]*UnionTags
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func init() {
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unionRegistry = make(map[reflect.Type]*UnionTags)
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}
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// Registers a union type in this context. Pass the union interface and the
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// list of types associated with it, sorted ascending by their union tag.
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func RegisterUnion(iface interface{}) *UnionTags {
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ity := reflect.TypeOf(iface).Elem()
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if _, ok := unionRegistry[ity]; ok {
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panic(fmt.Errorf("Type %s has already been registered", ity.Name()))
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}
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if !ity.Implements(reflect.TypeOf((*Union)(nil)).Elem()) {
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panic(fmt.Errorf("Type %s does not implement bare.Union", ity.Name()))
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}
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utypes := &UnionTags{
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iface: ity,
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tags: make(map[reflect.Type]uint64),
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types: make(map[uint64]reflect.Type),
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}
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unionRegistry[ity] = utypes
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return utypes
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}
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func (ut *UnionTags) Member(t interface{}, tag uint64) *UnionTags {
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ty := reflect.TypeOf(t)
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if !ty.AssignableTo(ut.iface) {
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panic(fmt.Errorf("Type %s does not implement interface %s",
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ty.Name(), ut.iface.Name()))
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}
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if _, ok := ut.tags[ty]; ok {
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panic(fmt.Errorf("Type %s is already registered for union %s",
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ty.Name(), ut.iface.Name()))
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}
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if _, ok := ut.types[tag]; ok {
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panic(fmt.Errorf("Tag %d is already registered for union %s",
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tag, ut.iface.Name()))
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}
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ut.tags[ty] = tag
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ut.types[tag] = ty
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return ut
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}
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func (ut *UnionTags) TagFor(v interface{}) (uint64, bool) {
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tag, ok := ut.tags[reflect.TypeOf(v)]
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return tag, ok
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}
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func (ut *UnionTags) TypeFor(tag uint64) (reflect.Type, bool) {
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t, ok := ut.types[tag]
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return t, ok
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}
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