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iterator.go
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/
iterator.go
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/*
* Copyright 2021 ByteDance Inc.
*
* 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
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package ast
import (
`fmt`
`github.com/bytedance/sonic/internal/native/types`
)
type Pair struct {
Key string
Value Node
}
// Values returns iterator for array's children traversal
func (self *Node) Values() (ListIterator, error) {
if err := self.should(types.V_ARRAY, "an array"); err != nil {
return ListIterator{}, err
}
return self.values(), nil
}
func (self *Node) values() ListIterator {
return ListIterator{Iterator{p: self}}
}
// Properties returns iterator for object's children traversal
func (self *Node) Properties() (ObjectIterator, error) {
if err := self.should(types.V_OBJECT, "an object"); err != nil {
return ObjectIterator{}, err
}
return self.properties(), nil
}
func (self *Node) properties() ObjectIterator {
return ObjectIterator{Iterator{p: self}}
}
type Iterator struct {
i int
p *Node
}
func (self *Iterator) Pos() int {
return self.i
}
func (self *Iterator) Len() int {
return self.p.len()
}
// HasNext reports if it is the end of iteration or has error.
func (self *Iterator) HasNext() bool {
if !self.p.isLazy() {
return self.p.Valid() && self.i < self.p.len()
} else if self.p.t == _V_ARRAY_LAZY {
return self.p.skipNextNode().Valid()
} else if self.p.t == _V_OBJECT_LAZY {
pair := self.p.skipNextPair()
if pair == nil {
return false
}
return pair.Value.Valid()
}
return false
}
// ListIterator is specialized iterator for V_ARRAY
type ListIterator struct {
Iterator
}
// ObjectIterator is specialized iterator for V_ARRAY
type ObjectIterator struct {
Iterator
}
func (self *ListIterator) next() *Node {
next_start:
if !self.HasNext() {
return nil
} else {
n := self.p.nodeAt(self.i)
self.i++
if !n.Exists() {
goto next_start
}
return n
}
}
// Next scans through children of underlying V_ARRAY,
// copies each child to v, and returns .HasNext().
func (self *ListIterator) Next(v *Node) bool {
n := self.next()
if n == nil {
return false
}
*v = *n
return true
}
func (self *ObjectIterator) next() *Pair {
next_start:
if !self.HasNext() {
return nil
} else {
n := self.p.pairAt(self.i)
self.i++
if n == nil || !n.Value.Exists() {
goto next_start
}
return n
}
}
// Next scans through children of underlying V_OBJECT,
// copies each child to v, and returns .HasNext().
func (self *ObjectIterator) Next(p *Pair) bool {
n := self.next()
if n == nil {
return false
}
*p = *n
return true
}
// Sequence represents scanning path of single-layer nodes.
// Index indicates the value's order in both V_ARRAY and V_OBJECT json.
// Key is the value's key (for V_OBJECT json only, otherwise it will be nil).
type Sequence struct {
Index int
Key *string
// Level int
}
// String is string representation of one Sequence
func (s Sequence) String() string {
k := ""
if s.Key != nil {
k = *s.Key
}
return fmt.Sprintf("Sequence(%d, %q)", s.Index, k)
}
type Scanner func(path Sequence, node *Node) bool
// ForEach scans one V_OBJECT node's children from JSON head to tail,
// and pass the Sequence and Node of corresponding JSON value.
//
// Especailly, if the node is not V_ARRAY or V_OBJECT,
// the node itself will be returned and Sequence.Index == -1.
//
// NOTICE: A unsetted node WON'T trigger sc, but its index still counts into Path.Index
func (self *Node) ForEach(sc Scanner) error {
switch self.itype() {
case types.V_ARRAY:
iter, err := self.Values()
if err != nil {
return err
}
v := iter.next()
for v != nil {
if !sc(Sequence{iter.i-1, nil}, v) {
return nil
}
v = iter.next()
}
case types.V_OBJECT:
iter, err := self.Properties()
if err != nil {
return err
}
v := iter.next()
for v != nil {
if !sc(Sequence{iter.i-1, &v.Key}, &v.Value) {
return nil
}
v = iter.next()
}
default:
if self.Check() != nil {
return self
}
sc(Sequence{-1, nil}, self)
}
return nil
}