538 lines
8.3 KiB
Go
538 lines
8.3 KiB
Go
package qcode
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import (
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"errors"
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"fmt"
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"sync"
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"unsafe"
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"github.com/dosco/super-graph/util"
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)
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var (
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errEOT = errors.New("end of tokens")
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)
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type parserType int32
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const (
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maxFields = 100
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maxArgs = 10
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)
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const (
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parserError parserType = iota
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parserEOF
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opQuery
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opMutate
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opSub
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NodeStr
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NodeInt
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NodeFloat
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NodeBool
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NodeObj
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NodeList
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NodeVar
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)
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type Operation struct {
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Type parserType
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Name string
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Args []Arg
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argsA [10]Arg
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Fields []Field
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fieldsA [10]Field
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}
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var zeroOperation = Operation{}
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func (o *Operation) Reset() {
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*o = zeroOperation
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}
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type Field struct {
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ID int32
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ParentID int32
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Name string
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Alias string
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Args []Arg
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argsA [5]Arg
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Children []int32
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childrenA [5]int32
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}
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type Arg struct {
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Name string
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Val *Node
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}
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type Node struct {
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Type parserType
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Name string
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Val string
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Parent *Node
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Children []*Node
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exp *Exp
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}
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var zeroNode = Node{}
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func (n *Node) Reset() {
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*n = zeroNode
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}
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type Parser struct {
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input []byte // the string being scanned
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pos int
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items []item
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err error
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}
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var nodePool = sync.Pool{
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New: func() interface{} { return new(Node) },
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}
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var opPool = sync.Pool{
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New: func() interface{} { return new(Operation) },
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}
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var lexPool = sync.Pool{
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New: func() interface{} { return new(lexer) },
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}
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func Parse(gql []byte) (*Operation, error) {
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return parseSelectionSet(gql)
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}
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func ParseArgValue(argVal string) (*Node, error) {
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l := lexPool.Get().(*lexer)
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l.Reset()
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if err := lex(l, []byte(argVal)); err != nil {
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return nil, err
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}
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p := &Parser{
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input: l.input,
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pos: -1,
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items: l.items,
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}
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op, err := p.parseValue()
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lexPool.Put(l)
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return op, err
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}
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func parseSelectionSet(gql []byte) (*Operation, error) {
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var err error
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if len(gql) == 0 {
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return nil, errors.New("blank query")
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}
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l := lexPool.Get().(*lexer)
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l.Reset()
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if err = lex(l, gql); err != nil {
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return nil, err
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}
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p := &Parser{
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input: l.input,
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pos: -1,
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items: l.items,
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}
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var op *Operation
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if p.peek(itemObjOpen) {
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p.ignore()
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op, err = p.parseQueryOp()
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} else {
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op, err = p.parseOp()
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}
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if err != nil {
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return nil, err
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}
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lexPool.Put(l)
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if err != nil {
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return nil, err
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}
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return op, err
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}
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func (p *Parser) next() item {
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n := p.pos + 1
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if n >= len(p.items) {
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p.err = errEOT
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return item{_type: itemEOF}
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}
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p.pos = n
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return p.items[p.pos]
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}
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func (p *Parser) ignore() {
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n := p.pos + 1
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if n >= len(p.items) {
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p.err = errEOT
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return
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}
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p.pos = n
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}
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func (p *Parser) peek(types ...itemType) bool {
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n := p.pos + 1
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if p.items[n]._type == itemEOF {
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return false
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}
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if n >= len(p.items) {
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return false
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}
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for i := 0; i < len(types); i++ {
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if p.items[n]._type == types[i] {
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return true
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}
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}
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return false
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}
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func (p *Parser) parseOp() (*Operation, error) {
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if !p.peek(itemQuery, itemMutation, itemSub) {
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err := errors.New("expecting a query, mutation or subscription")
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return nil, err
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}
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item := p.next()
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op := opPool.Get().(*Operation)
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op.Reset()
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switch item._type {
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case itemQuery:
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op.Type = opQuery
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case itemMutation:
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op.Type = opMutate
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case itemSub:
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op.Type = opSub
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}
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op.Fields = op.fieldsA[:0]
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op.Args = op.argsA[:0]
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var err error
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if p.peek(itemName) {
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op.Name = p.val(p.next())
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}
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if p.peek(itemArgsOpen) {
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p.ignore()
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op.Args, err = p.parseArgs(op.Args)
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if err != nil {
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return nil, err
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}
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}
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if p.peek(itemObjOpen) {
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p.ignore()
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for n := 0; n < 10; n++ {
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if !p.peek(itemName) {
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break
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}
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op.Fields, err = p.parseFields(op.Fields)
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if err != nil {
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return nil, err
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}
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}
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}
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return op, nil
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}
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func (p *Parser) parseQueryOp() (*Operation, error) {
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op := opPool.Get().(*Operation)
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op.Reset()
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op.Type = opQuery
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op.Fields = op.fieldsA[:0]
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op.Args = op.argsA[:0]
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var err error
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for n := 0; n < 10; n++ {
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if !p.peek(itemName) {
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break
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}
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op.Fields, err = p.parseFields(op.Fields)
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if err != nil {
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return nil, err
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}
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}
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return op, nil
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}
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func (p *Parser) parseFields(fields []Field) ([]Field, error) {
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st := util.NewStack()
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for {
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if len(fields) >= maxFields {
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return nil, fmt.Errorf("too many fields (max %d)", maxFields)
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}
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if p.peek(itemObjClose) {
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p.ignore()
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st.Pop()
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if st.Len() == 0 {
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break
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}
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continue
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}
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if !p.peek(itemName) {
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return nil, errors.New("expecting an alias or field name")
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}
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fields = append(fields, Field{ID: int32(len(fields))})
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f := &fields[(len(fields) - 1)]
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f.Args = f.argsA[:0]
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f.Children = f.childrenA[:0]
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if err := p.parseField(f); err != nil {
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return nil, err
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}
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intf := st.Peek()
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if pid, ok := intf.(int32); ok {
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f.ParentID = pid
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fields[pid].Children = append(fields[pid].Children, f.ID)
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} else {
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f.ParentID = -1
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}
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if p.peek(itemObjOpen) {
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p.ignore()
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st.Push(f.ID)
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}
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}
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return fields, nil
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}
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func (p *Parser) parseField(f *Field) error {
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var err error
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f.Name = p.val(p.next())
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if p.peek(itemColon) {
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p.ignore()
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if p.peek(itemName) {
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f.Alias = f.Name
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f.Name = p.val(p.next())
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} else {
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return errors.New("expecting an aliased field name")
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}
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}
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if p.peek(itemArgsOpen) {
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p.ignore()
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if f.Args, err = p.parseArgs(f.Args); err != nil {
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return err
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}
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}
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return nil
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}
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func (p *Parser) parseArgs(args []Arg) ([]Arg, error) {
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var err error
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for {
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if len(args) >= maxArgs {
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return nil, fmt.Errorf("too many args (max %d)", maxArgs)
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}
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if p.peek(itemArgsClose) {
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p.ignore()
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break
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}
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if !p.peek(itemName) {
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return nil, errors.New("expecting an argument name")
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}
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args = append(args, Arg{Name: p.val(p.next())})
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arg := &args[(len(args) - 1)]
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if !p.peek(itemColon) {
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return nil, errors.New("missing ':' after argument name")
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}
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p.ignore()
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arg.Val, err = p.parseValue()
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if err != nil {
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return nil, err
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}
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}
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return args, nil
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}
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func (p *Parser) parseList() (*Node, error) {
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nodes := []*Node{}
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parent := nodePool.Get().(*Node)
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parent.Reset()
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var ty parserType
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for {
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if p.peek(itemListClose) {
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p.ignore()
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break
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}
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node, err := p.parseValue()
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if err != nil {
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return nil, err
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}
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if ty == 0 {
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ty = node.Type
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} else {
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if ty != node.Type {
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return nil, errors.New("All values in a list must be of the same type")
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}
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}
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node.Parent = parent
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nodes = append(nodes, node)
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}
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if len(nodes) == 0 {
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return nil, errors.New("List cannot be empty")
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}
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parent.Type = NodeList
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parent.Children = nodes
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return parent, nil
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}
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func (p *Parser) parseObj() (*Node, error) {
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nodes := []*Node{}
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parent := nodePool.Get().(*Node)
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parent.Reset()
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for {
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if p.peek(itemObjClose) {
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p.ignore()
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break
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}
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if !p.peek(itemName) {
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return nil, errors.New("expecting an argument name")
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}
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nodeName := p.val(p.next())
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if !p.peek(itemColon) {
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return nil, errors.New("missing ':' after Field argument name")
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}
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p.ignore()
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node, err := p.parseValue()
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if err != nil {
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return nil, err
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}
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node.Name = nodeName
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node.Parent = parent
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nodes = append(nodes, node)
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}
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parent.Type = NodeObj
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parent.Children = nodes
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return parent, nil
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}
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func (p *Parser) parseValue() (*Node, error) {
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if p.peek(itemListOpen) {
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p.ignore()
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return p.parseList()
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}
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if p.peek(itemObjOpen) {
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p.ignore()
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return p.parseObj()
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}
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item := p.next()
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node := nodePool.Get().(*Node)
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node.Reset()
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switch item._type {
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case itemIntVal:
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node.Type = NodeInt
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case itemFloatVal:
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node.Type = NodeFloat
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case itemStringVal:
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node.Type = NodeStr
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case itemBoolVal:
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node.Type = NodeBool
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case itemName:
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node.Type = NodeStr
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case itemVariable:
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node.Type = NodeVar
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default:
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return nil, fmt.Errorf("expecting a number, string, object, list or variable as an argument value (not %s)", p.val(p.next()))
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}
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node.Val = p.val(item)
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return node, nil
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}
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func (p *Parser) val(v item) string {
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return b2s(p.input[v.pos:v.end])
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}
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func b2s(b []byte) string {
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return *(*string)(unsafe.Pointer(&b))
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}
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func (t parserType) String() string {
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var v string
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switch t {
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case parserEOF:
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v = "EOF"
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case parserError:
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v = "error"
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case opQuery:
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v = "query"
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case opMutate:
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v = "mutation"
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case opSub:
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v = "subscription"
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case NodeStr:
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v = "node-string"
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case NodeInt:
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v = "node-int"
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case NodeFloat:
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v = "node-float"
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case NodeBool:
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v = "node-bool"
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case NodeVar:
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v = "node-var"
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case NodeObj:
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v = "node-obj"
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case NodeList:
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v = "node-list"
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}
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return fmt.Sprintf("<%s>", v)
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}
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func FreeNode(n *Node) {
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nodePool.Put(n)
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}
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