Matteo Scandolo | a428586 | 2020-12-01 18:10:10 -0800 | [diff] [blame^] | 1 | package reflect2 |
| 2 | |
| 3 | import ( |
| 4 | "reflect" |
| 5 | "runtime" |
| 6 | "strings" |
| 7 | "sync" |
| 8 | "unsafe" |
| 9 | ) |
| 10 | |
| 11 | // typelinks1 for 1.5 ~ 1.6 |
| 12 | //go:linkname typelinks1 reflect.typelinks |
| 13 | func typelinks1() [][]unsafe.Pointer |
| 14 | |
| 15 | // typelinks2 for 1.7 ~ |
| 16 | //go:linkname typelinks2 reflect.typelinks |
| 17 | func typelinks2() (sections []unsafe.Pointer, offset [][]int32) |
| 18 | |
| 19 | // initOnce guards initialization of types and packages |
| 20 | var initOnce sync.Once |
| 21 | |
| 22 | var types map[string]reflect.Type |
| 23 | var packages map[string]map[string]reflect.Type |
| 24 | |
| 25 | // discoverTypes initializes types and packages |
| 26 | func discoverTypes() { |
| 27 | types = make(map[string]reflect.Type) |
| 28 | packages = make(map[string]map[string]reflect.Type) |
| 29 | |
| 30 | ver := runtime.Version() |
| 31 | if ver == "go1.5" || strings.HasPrefix(ver, "go1.5.") { |
| 32 | loadGo15Types() |
| 33 | } else if ver == "go1.6" || strings.HasPrefix(ver, "go1.6.") { |
| 34 | loadGo15Types() |
| 35 | } else { |
| 36 | loadGo17Types() |
| 37 | } |
| 38 | } |
| 39 | |
| 40 | func loadGo15Types() { |
| 41 | var obj interface{} = reflect.TypeOf(0) |
| 42 | typePtrss := typelinks1() |
| 43 | for _, typePtrs := range typePtrss { |
| 44 | for _, typePtr := range typePtrs { |
| 45 | (*emptyInterface)(unsafe.Pointer(&obj)).word = typePtr |
| 46 | typ := obj.(reflect.Type) |
| 47 | if typ.Kind() == reflect.Ptr && typ.Elem().Kind() == reflect.Struct { |
| 48 | loadedType := typ.Elem() |
| 49 | pkgTypes := packages[loadedType.PkgPath()] |
| 50 | if pkgTypes == nil { |
| 51 | pkgTypes = map[string]reflect.Type{} |
| 52 | packages[loadedType.PkgPath()] = pkgTypes |
| 53 | } |
| 54 | types[loadedType.String()] = loadedType |
| 55 | pkgTypes[loadedType.Name()] = loadedType |
| 56 | } |
| 57 | if typ.Kind() == reflect.Slice && typ.Elem().Kind() == reflect.Ptr && |
| 58 | typ.Elem().Elem().Kind() == reflect.Struct { |
| 59 | loadedType := typ.Elem().Elem() |
| 60 | pkgTypes := packages[loadedType.PkgPath()] |
| 61 | if pkgTypes == nil { |
| 62 | pkgTypes = map[string]reflect.Type{} |
| 63 | packages[loadedType.PkgPath()] = pkgTypes |
| 64 | } |
| 65 | types[loadedType.String()] = loadedType |
| 66 | pkgTypes[loadedType.Name()] = loadedType |
| 67 | } |
| 68 | } |
| 69 | } |
| 70 | } |
| 71 | |
| 72 | func loadGo17Types() { |
| 73 | var obj interface{} = reflect.TypeOf(0) |
| 74 | sections, offset := typelinks2() |
| 75 | for i, offs := range offset { |
| 76 | rodata := sections[i] |
| 77 | for _, off := range offs { |
| 78 | (*emptyInterface)(unsafe.Pointer(&obj)).word = resolveTypeOff(unsafe.Pointer(rodata), off) |
| 79 | typ := obj.(reflect.Type) |
| 80 | if typ.Kind() == reflect.Ptr && typ.Elem().Kind() == reflect.Struct { |
| 81 | loadedType := typ.Elem() |
| 82 | pkgTypes := packages[loadedType.PkgPath()] |
| 83 | if pkgTypes == nil { |
| 84 | pkgTypes = map[string]reflect.Type{} |
| 85 | packages[loadedType.PkgPath()] = pkgTypes |
| 86 | } |
| 87 | types[loadedType.String()] = loadedType |
| 88 | pkgTypes[loadedType.Name()] = loadedType |
| 89 | } |
| 90 | } |
| 91 | } |
| 92 | } |
| 93 | |
| 94 | type emptyInterface struct { |
| 95 | typ unsafe.Pointer |
| 96 | word unsafe.Pointer |
| 97 | } |
| 98 | |
| 99 | // TypeByName return the type by its name, just like Class.forName in java |
| 100 | func TypeByName(typeName string) Type { |
| 101 | initOnce.Do(discoverTypes) |
| 102 | return Type2(types[typeName]) |
| 103 | } |
| 104 | |
| 105 | // TypeByPackageName return the type by its package and name |
| 106 | func TypeByPackageName(pkgPath string, name string) Type { |
| 107 | initOnce.Do(discoverTypes) |
| 108 | pkgTypes := packages[pkgPath] |
| 109 | if pkgTypes == nil { |
| 110 | return nil |
| 111 | } |
| 112 | return Type2(pkgTypes[name]) |
| 113 | } |