mirror of
https://github.com/vbatts/go-mtree.git
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290 lines
9.6 KiB
Go
290 lines
9.6 KiB
Go
package cli
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import (
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"flag"
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"reflect"
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)
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type (
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// SliceFlag extends implementations like StringSliceFlag and IntSliceFlag with support for using slices directly,
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// as Value and/or Destination.
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// See also SliceFlagTarget, MultiStringFlag, MultiFloat64Flag, MultiInt64Flag, MultiIntFlag.
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SliceFlag[T SliceFlagTarget[E], S ~[]E, E any] struct {
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Target T
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Value S
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Destination *S
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}
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// SliceFlagTarget models a target implementation for use with SliceFlag.
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// The three methods, SetValue, SetDestination, and GetDestination, are necessary to propagate Value and
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// Destination, where Value is propagated inwards (initially), and Destination is propagated outwards (on every
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// update).
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SliceFlagTarget[E any] interface {
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Flag
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RequiredFlag
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DocGenerationFlag
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VisibleFlag
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CategorizableFlag
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// SetValue should propagate the given slice to the target, ideally as a new value.
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// Note that a nil slice should nil/clear any existing value (modelled as ~[]E).
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SetValue(slice []E)
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// SetDestination should propagate the given slice to the target, ideally as a new value.
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// Note that a nil slice should nil/clear any existing value (modelled as ~*[]E).
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SetDestination(slice []E)
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// GetDestination should return the current value referenced by any destination, or nil if nil/unset.
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GetDestination() []E
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}
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// MultiStringFlag extends StringSliceFlag with support for using slices directly, as Value and/or Destination.
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// See also SliceFlag.
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MultiStringFlag = SliceFlag[*StringSliceFlag, []string, string]
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// MultiFloat64Flag extends Float64SliceFlag with support for using slices directly, as Value and/or Destination.
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// See also SliceFlag.
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MultiFloat64Flag = SliceFlag[*Float64SliceFlag, []float64, float64]
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// MultiInt64Flag extends Int64SliceFlag with support for using slices directly, as Value and/or Destination.
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// See also SliceFlag.
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MultiInt64Flag = SliceFlag[*Int64SliceFlag, []int64, int64]
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// MultiIntFlag extends IntSliceFlag with support for using slices directly, as Value and/or Destination.
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// See also SliceFlag.
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MultiIntFlag = SliceFlag[*IntSliceFlag, []int, int]
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flagValueHook struct {
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value Generic
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hook func()
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}
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)
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var (
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// compile time assertions
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_ SliceFlagTarget[string] = (*StringSliceFlag)(nil)
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_ SliceFlagTarget[string] = (*SliceFlag[*StringSliceFlag, []string, string])(nil)
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_ SliceFlagTarget[string] = (*MultiStringFlag)(nil)
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_ SliceFlagTarget[float64] = (*MultiFloat64Flag)(nil)
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_ SliceFlagTarget[int64] = (*MultiInt64Flag)(nil)
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_ SliceFlagTarget[int] = (*MultiIntFlag)(nil)
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_ Generic = (*flagValueHook)(nil)
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_ Serializer = (*flagValueHook)(nil)
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)
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func (x *SliceFlag[T, S, E]) Apply(set *flag.FlagSet) error {
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x.Target.SetValue(x.convertSlice(x.Value))
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destination := x.Destination
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if destination == nil {
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x.Target.SetDestination(nil)
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return x.Target.Apply(set)
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}
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x.Target.SetDestination(x.convertSlice(*destination))
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return applyFlagValueHook(set, x.Target.Apply, func() {
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*destination = x.Target.GetDestination()
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})
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}
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func (x *SliceFlag[T, S, E]) convertSlice(slice S) []E {
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result := make([]E, len(slice))
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copy(result, slice)
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return result
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}
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func (x *SliceFlag[T, S, E]) SetValue(slice S) {
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x.Value = slice
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}
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func (x *SliceFlag[T, S, E]) SetDestination(slice S) {
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if slice != nil {
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x.Destination = &slice
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} else {
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x.Destination = nil
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}
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}
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func (x *SliceFlag[T, S, E]) GetDestination() S {
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if destination := x.Destination; destination != nil {
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return *destination
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}
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return nil
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}
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func (x *SliceFlag[T, S, E]) String() string { return x.Target.String() }
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func (x *SliceFlag[T, S, E]) Names() []string { return x.Target.Names() }
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func (x *SliceFlag[T, S, E]) IsSet() bool { return x.Target.IsSet() }
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func (x *SliceFlag[T, S, E]) IsRequired() bool { return x.Target.IsRequired() }
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func (x *SliceFlag[T, S, E]) TakesValue() bool { return x.Target.TakesValue() }
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func (x *SliceFlag[T, S, E]) GetUsage() string { return x.Target.GetUsage() }
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func (x *SliceFlag[T, S, E]) GetValue() string { return x.Target.GetValue() }
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func (x *SliceFlag[T, S, E]) GetDefaultText() string { return x.Target.GetDefaultText() }
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func (x *SliceFlag[T, S, E]) GetEnvVars() []string { return x.Target.GetEnvVars() }
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func (x *SliceFlag[T, S, E]) IsVisible() bool { return x.Target.IsVisible() }
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func (x *SliceFlag[T, S, E]) GetCategory() string { return x.Target.GetCategory() }
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func (x *flagValueHook) Set(value string) error {
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if err := x.value.Set(value); err != nil {
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return err
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}
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x.hook()
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return nil
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}
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func (x *flagValueHook) String() string {
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// note: this is necessary due to the way Go's flag package handles defaults
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isZeroValue := func(f flag.Value, v string) bool {
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/*
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https://cs.opensource.google/go/go/+/refs/tags/go1.18.3:src/flag/flag.go;drc=2580d0e08d5e9f979b943758d3c49877fb2324cb;l=453
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Copyright (c) 2009 The Go Authors. All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are
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met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above
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copyright notice, this list of conditions and the following disclaimer
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in the documentation and/or other materials provided with the
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distribution.
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* Neither the name of Google Inc. nor the names of its
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contributors may be used to endorse or promote products derived from
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this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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// Build a zero value of the flag's Value type, and see if the
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// result of calling its String method equals the value passed in.
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// This works unless the Value type is itself an interface type.
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typ := reflect.TypeOf(f)
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var z reflect.Value
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if typ.Kind() == reflect.Pointer {
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z = reflect.New(typ.Elem())
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} else {
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z = reflect.Zero(typ)
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}
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return v == z.Interface().(flag.Value).String()
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}
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if x.value != nil {
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// only return non-empty if not the same string as returned by the zero value
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if s := x.value.String(); !isZeroValue(x.value, s) {
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return s
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}
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}
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return ``
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}
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func (x *flagValueHook) Serialize() string {
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if value, ok := x.value.(Serializer); ok {
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return value.Serialize()
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}
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return x.String()
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}
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// applyFlagValueHook wraps calls apply then wraps flags to call a hook function on update and after initial apply.
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func applyFlagValueHook(set *flag.FlagSet, apply func(set *flag.FlagSet) error, hook func()) error {
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if apply == nil || set == nil || hook == nil {
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panic(`invalid input`)
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}
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var tmp flag.FlagSet
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if err := apply(&tmp); err != nil {
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return err
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}
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tmp.VisitAll(func(f *flag.Flag) { set.Var(&flagValueHook{value: f.Value, hook: hook}, f.Name, f.Usage) })
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hook()
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return nil
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}
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// newSliceFlagValue is for implementing SliceFlagTarget.SetValue and SliceFlagTarget.SetDestination.
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// It's e.g. as part of StringSliceFlag.SetValue, using the factory NewStringSlice.
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func newSliceFlagValue[R any, S ~[]E, E any](factory func(defaults ...E) *R, defaults S) *R {
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if defaults == nil {
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return nil
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}
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return factory(defaults...)
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}
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// unwrapFlagValue strips any/all *flagValueHook wrappers.
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func unwrapFlagValue(v flag.Value) flag.Value {
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for {
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h, ok := v.(*flagValueHook)
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if !ok {
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return v
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}
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v = h.value
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}
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}
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// NOTE: the methods below are in this file to make use of the build constraint
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func (f *Float64SliceFlag) SetValue(slice []float64) {
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f.Value = newSliceFlagValue(NewFloat64Slice, slice)
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}
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func (f *Float64SliceFlag) SetDestination(slice []float64) {
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f.Destination = newSliceFlagValue(NewFloat64Slice, slice)
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}
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func (f *Float64SliceFlag) GetDestination() []float64 {
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if destination := f.Destination; destination != nil {
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return destination.Value()
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}
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return nil
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}
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func (f *Int64SliceFlag) SetValue(slice []int64) {
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f.Value = newSliceFlagValue(NewInt64Slice, slice)
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}
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func (f *Int64SliceFlag) SetDestination(slice []int64) {
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f.Destination = newSliceFlagValue(NewInt64Slice, slice)
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}
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func (f *Int64SliceFlag) GetDestination() []int64 {
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if destination := f.Destination; destination != nil {
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return destination.Value()
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}
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return nil
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}
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func (f *IntSliceFlag) SetValue(slice []int) {
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f.Value = newSliceFlagValue(NewIntSlice, slice)
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}
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func (f *IntSliceFlag) SetDestination(slice []int) {
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f.Destination = newSliceFlagValue(NewIntSlice, slice)
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}
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func (f *IntSliceFlag) GetDestination() []int {
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if destination := f.Destination; destination != nil {
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return destination.Value()
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}
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return nil
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}
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func (f *StringSliceFlag) SetValue(slice []string) {
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f.Value = newSliceFlagValue(NewStringSlice, slice)
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}
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func (f *StringSliceFlag) SetDestination(slice []string) {
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f.Destination = newSliceFlagValue(NewStringSlice, slice)
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}
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func (f *StringSliceFlag) GetDestination() []string {
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if destination := f.Destination; destination != nil {
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return destination.Value()
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}
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return nil
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}
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