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// Copyright (C) 2015 The Android Open Source Project
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
package path
import (
// Slice is a path that refers to a subset of the elements in an array.
type Slice struct {
Array Path // The path to the array.
Start uint64
End uint64
// String returns the string representation of the path.
func (n *Slice) String() string { return n.Path() }
// Path implements the Path interface.
func (n *Slice) Path() string {
return fmt.Sprintf("%v[%d:%d]", n.Array.Path(), n.Start, n.End)
// Base implements the Path interface, returning the path to the array.
func (n *Slice) Base() Path {
return n.Array
// Clone implements the Path interface, returning a deep-copy of this path.
func (n *Slice) Clone() Path {
return &Slice{Array: n.Array.Clone(), Start: n.Start, End: n.End}
// Validate implements the Path interface.
func (n *Slice) Validate() error {
switch {
case n == nil:
return fmt.Errorf("Slice is nil")
case n.Array == nil:
return fmt.Errorf("Slice.Array is nil")
case n.End < n.Start:
return fmt.Errorf("Slice.End (%d) is before Slice.Start (%d)", n.End, n.Start)
return n.Array.Validate()
// Index returns the path to the i'th element in the slice.
func (n *Slice) Index(i uint64) Path {
return &ArrayIndex{Array: n, Index: i}
// FindSlice returns the first Slice found traversing the path p.
// If no Slice was found, then nil is returned.
func FindSlice(p Path) *Slice {
for p != nil {
if p, ok := p.(*Slice); ok {
return p
p = p.Base()
return nil