63 lines
1.5 KiB
Go
63 lines
1.5 KiB
Go
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package sprig
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import (
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"reflect"
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)
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// dfault checks whether `given` is set, and returns default if not set.
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//
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// This returns `d` if `given` appears not to be set, and `given` otherwise.
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//
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// For numeric types 0 is unset.
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// For strings, maps, arrays, and slices, len() = 0 is considered unset.
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// For bool, false is unset.
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// Structs are never considered unset.
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//
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// For everything else, including pointers, a nil value is unset.
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func dfault(d interface{}, given ...interface{}) interface{} {
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if empty(given) || empty(given[0]) {
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return d
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}
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return given[0]
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}
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// empty returns true if the given value has the zero value for its type.
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func empty(given interface{}) bool {
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g := reflect.ValueOf(given)
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if !g.IsValid() {
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return true
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}
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// Basically adapted from text/template.isTrue
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switch g.Kind() {
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default:
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return g.IsNil()
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case reflect.Array, reflect.Slice, reflect.Map, reflect.String:
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return g.Len() == 0
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case reflect.Bool:
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return g.Bool() == false
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case reflect.Complex64, reflect.Complex128:
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return g.Complex() == 0
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case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
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return g.Int() == 0
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case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
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return g.Uint() == 0
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case reflect.Float32, reflect.Float64:
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return g.Float() == 0
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case reflect.Struct:
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return false
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}
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return true
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}
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// coalesce returns the first non-empty value.
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func coalesce(v ...interface{}) interface{} {
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for _, val := range v {
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if !empty(val) {
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return val
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}
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}
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return nil
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}
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