//This package is copied from Go library text/template.
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//The original private functions indirect and printableValue
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//are exported as public functions.
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package template
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import (
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"fmt"
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"reflect"
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)
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var Indirect = indirect
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var PrintableValue = printableValue
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var (
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errorType = reflect.TypeOf((*error)(nil)).Elem()
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fmtStringerType = reflect.TypeOf((*fmt.Stringer)(nil)).Elem()
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)
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// indirect returns the item at the end of indirection, and a bool to indicate if it's nil.
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// We indirect through pointers and empty interfaces (only) because
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// non-empty interfaces have methods we might need.
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func indirect(v reflect.Value) (rv reflect.Value, isNil bool) {
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for ; v.Kind() == reflect.Ptr || v.Kind() == reflect.Interface; v = v.Elem() {
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if v.IsNil() {
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return v, true
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}
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if v.Kind() == reflect.Interface && v.NumMethod() > 0 {
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break
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}
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}
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return v, false
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}
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// printableValue returns the, possibly indirected, interface value inside v that
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// is best for a call to formatted printer.
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func printableValue(v reflect.Value) (interface{}, bool) {
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if v.Kind() == reflect.Ptr {
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v, _ = indirect(v) // fmt.Fprint handles nil.
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}
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if !v.IsValid() {
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return "<no value>", true
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}
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if !v.Type().Implements(errorType) && !v.Type().Implements(fmtStringerType) {
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if v.CanAddr() && (reflect.PtrTo(v.Type()).Implements(errorType) || reflect.PtrTo(v.Type()).Implements(fmtStringerType)) {
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v = v.Addr()
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} else {
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switch v.Kind() {
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case reflect.Chan, reflect.Func:
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return nil, false
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}
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}
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}
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return v.Interface(), true
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}
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// canBeNil reports whether an untyped nil can be assigned to the type. See reflect.Zero.
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func canBeNil(typ reflect.Type) bool {
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switch typ.Kind() {
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case reflect.Chan, reflect.Func, reflect.Interface, reflect.Map, reflect.Ptr, reflect.Slice:
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return true
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}
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return false
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}
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// isTrue reports whether the value is 'true', in the sense of not the zero of its type,
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// and whether the value has a meaningful truth value.
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func isTrue(val reflect.Value) (truth, ok bool) {
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if !val.IsValid() {
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// Something like var x interface{}, never set. It's a form of nil.
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return false, true
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}
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switch val.Kind() {
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case reflect.Array, reflect.Map, reflect.Slice, reflect.String:
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truth = val.Len() > 0
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case reflect.Bool:
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truth = val.Bool()
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case reflect.Complex64, reflect.Complex128:
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truth = val.Complex() != 0
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case reflect.Chan, reflect.Func, reflect.Ptr, reflect.Interface:
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truth = !val.IsNil()
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case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
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truth = val.Int() != 0
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case reflect.Float32, reflect.Float64:
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truth = val.Float() != 0
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case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
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truth = val.Uint() != 0
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case reflect.Struct:
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truth = true // Struct values are always true.
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default:
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return
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}
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return truth, true
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}
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