58 lines
1.5 KiB
Go
58 lines
1.5 KiB
Go
// Package structs is for manipulating structures with reflection
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package structs
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import (
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"reflect"
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)
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// SetFrom sets the public members of a from b
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//
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// a and b should be pointers to structs
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//
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// a can be a different type from b
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//
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// Only the Fields which have the same name and assignable type on a
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// and b will be set.
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//
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// This is useful for copying between almost identical structures that
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// are frequently present in auto-generated code for cloud storage
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// interfaces.
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func SetFrom(a, b interface{}) {
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ta := reflect.TypeOf(a).Elem()
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tb := reflect.TypeOf(b).Elem()
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va := reflect.ValueOf(a).Elem()
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vb := reflect.ValueOf(b).Elem()
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for i := 0; i < tb.NumField(); i++ {
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bField := vb.Field(i)
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tbField := tb.Field(i)
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name := tbField.Name
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aField := va.FieldByName(name)
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taField, found := ta.FieldByName(name)
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if found && aField.IsValid() && bField.IsValid() && aField.CanSet() && tbField.Type.AssignableTo(taField.Type) {
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aField.Set(bField)
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}
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}
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}
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// SetDefaults for a from b
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//
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// a and b should be pointers to the same kind of struct
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//
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// This copies the public members only from b to a. This is useful if
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// you can't just use a struct copy because it contains a private
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// mutex, e.g. as http.Transport.
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func SetDefaults(a, b interface{}) {
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pt := reflect.TypeOf(a)
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t := pt.Elem()
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va := reflect.ValueOf(a).Elem()
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vb := reflect.ValueOf(b).Elem()
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for i := 0; i < t.NumField(); i++ {
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aField := va.Field(i)
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// Set a from b if it is public
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if aField.CanSet() {
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bField := vb.Field(i)
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aField.Set(bField)
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}
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}
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}
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