elvish/eval/opt.go

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package eval
import (
"errors"
"github.com/elves/elvish/parse"
)
type OptSpec struct {
Name string
Default Value
}
type OptSet struct {
optSpecs []OptSpec
indices map[string]int
}
func NewOptSet(optSpecs ...OptSpec) *OptSet {
indices := make(map[string]int)
for i, optSpec := range optSpecs {
indices[optSpec.Name] = i
}
return &OptSet{optSpecs, indices}
}
func (os *OptSet) Pick(opts map[string]Value) ([]Value, error) {
vs := make([]Value, len(os.optSpecs))
for k, v := range opts {
if i, ok := os.indices[k]; ok {
vs[i] = v
} else {
return nil, errors.New("unknown option " + parse.Quote(k))
}
}
for i, optSpec := range os.optSpecs {
if vs[i] == nil {
vs[i] = optSpec.Default
}
}
return vs, nil
}
func (os *OptSet) MustPick(opts map[string]Value) []Value {
vs, err := os.Pick(opts)
maybeThrow(err)
return vs
}