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op_shuffle.go
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op_shuffle.go
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package spruce
import (
"fmt"
"math/rand"
"time"
"github.com/starkandwayne/goutils/tree"
. "github.com/geofffranks/spruce/log"
)
// ShuffleOperator ...
type ShuffleOperator struct{}
// Setup ...
func (ShuffleOperator) Setup() error {
return nil
}
// Phase ...
func (ShuffleOperator) Phase() OperatorPhase {
return EvalPhase
}
// Dependencies ...
func (ShuffleOperator) Dependencies(_ *Evaluator, _ []*Expr, _ []*tree.Cursor, auto []*tree.Cursor) []*tree.Cursor {
return auto
}
// Run ...
func (ShuffleOperator) Run(ev *Evaluator, args []*Expr) (*Response, error) {
DEBUG("running (( shuffle ... )) operation at $.%s", ev.Here)
defer DEBUG("done with (( shuffle ... )) operation at $%s\n", ev.Here)
var vals []interface{}
for i, arg := range args {
v, err := arg.Resolve(ev.Tree)
if err != nil {
DEBUG(" [%d]: resolution failed\n error: %s", i, err)
return nil, err
}
switch v.Type {
case Literal:
DEBUG(" arg[%d]: found string literal '%s'", i, v.Literal)
vals = append(vals, v.Literal)
case Reference:
DEBUG(" arg[%d]: trying to resolve reference $.%s", i, v.Reference)
s, err := v.Reference.Resolve(ev.Tree)
if err != nil {
DEBUG(" [%d]: resolution failed\n error: %s", i, err)
return nil, fmt.Errorf("Unable to resolve `%s`: %s", v.Reference, err)
}
switch s.(type) {
case []interface{}:
for _, thing := range s.([]interface{}) {
vals = append(vals, thing)
}
case map[interface{}]interface{}:
DEBUG(" [%d]: resolved to a map; error!", i)
return nil, fmt.Errorf("shuffle only accepts arrays and string values")
default:
vals = append(vals, s.(interface{}))
}
default:
DEBUG(" arg[%d]: I don't know what to do with '%v'", i, arg)
return nil, fmt.Errorf("shuffle operator only accepts key reference arguments")
}
DEBUG("")
}
return &Response{
Type: Replace,
Value: shuffle(vals),
}, nil
}
func init() {
RegisterOp("shuffle", ShuffleOperator{})
}
func shuffle(l []interface{}) []interface{} {
rand.Seed(time.Now().UnixNano())
rand.Shuffle(len(l), func(i, j int) { l[i], l[j] = l[j], l[i] })
return l
}