43 lines
1.2 KiB
Go
43 lines
1.2 KiB
Go
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package util
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import (
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"fmt"
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"reflect"
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"unsafe"
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)
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// Ptr returns the pointer to these things:
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// - First element of a slice or array, nil if it has zero length;
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// - The pointer itself if the parameter is a pointer, pointing to an scalar value.
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// It panics otherwise.
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func Ptr(d interface{}) (addr unsafe.Pointer) {
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if d == nil {
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return unsafe.Pointer(nil)
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}
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v := reflect.ValueOf(d)
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switch v.Type().Kind() {
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case reflect.Ptr:
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e := v.Elem()
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switch e.Kind() {
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case
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reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
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reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64,
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reflect.Float32, reflect.Float64:
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addr = unsafe.Pointer(e.UnsafeAddr())
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default:
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panic(fmt.Errorf("unsupported pointer to type %s; must be a slice or pointer to a singular scalar value or the first element of an array or slice", e.Kind()))
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}
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case reflect.Slice, reflect.Array:
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if v.Len() != 0 {
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addr = unsafe.Pointer(v.Index(0).UnsafeAddr())
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}
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case reflect.Uintptr:
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addr = unsafe.Pointer(d.(uintptr))
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default:
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panic(fmt.Errorf("unsupported type %s; must be a slice or pointer to a singular scalar value or the first element of an array or slice", v.Type()))
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}
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return
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}
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