super-graph/qcode/parse.go

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package qcode
import (
"errors"
"fmt"
"sync"
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"unsafe"
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"github.com/dosco/super-graph/util"
)
var (
errEOT = errors.New("end of tokens")
)
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type parserType int32
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const (
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maxFields = 100
maxArgs = 10
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parserError parserType = iota
parserEOF
opQuery
opMutate
opSub
nodeStr
nodeInt
nodeFloat
nodeBool
nodeObj
nodeList
nodeVar
)
type Operation struct {
Type parserType
Name string
Args []Arg
argsA [10]Arg
Fields []Field
fieldsA [10]Field
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}
var zeroOperation = Operation{}
func (o *Operation) Reset() {
*o = zeroOperation
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}
type Field struct {
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ID int32
ParentID int32
Name string
Alias string
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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}
type Arg struct {
Name string
Val *Node
}
type Node struct {
Type parserType
Name string
Val string
Parent *Node
Children []*Node
exp *Exp
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}
var zeroNode = Node{}
func (n *Node) Reset() {
*n = zeroNode
}
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type Parser struct {
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input []byte // the string being scanned
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pos int
items []item
depth int
err error
}
var nodePool = sync.Pool{
New: func() interface{} { return new(Node) },
}
var opPool = sync.Pool{
New: func() interface{} { return new(Operation) },
}
var lexPool = sync.Pool{
New: func() interface{} { return new(lexer) },
}
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func Parse(gql []byte) (*Operation, error) {
return parseSelectionSet(nil, gql)
}
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func ParseQuery(gql []byte) (*Operation, error) {
op := opPool.Get().(*Operation)
op.Reset()
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op.Type = opQuery
op.Name = ""
op.Fields = op.fieldsA[:0]
op.Args = op.argsA[:0]
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return parseSelectionSet(op, gql)
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}
func ParseArgValue(argVal string) (*Node, error) {
l := lexPool.Get().(*lexer)
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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p := &Parser{
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input: l.input,
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pos: -1,
items: l.items,
}
op, err := p.parseValue()
lexPool.Put(l)
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return op, err
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}
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func parseSelectionSet(op *Operation, gql []byte) (*Operation, error) {
var err error
if len(gql) == 0 {
return nil, errors.New("blank query")
}
l := lexPool.Get().(*lexer)
l.Reset()
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if err = lex(l, gql); err != nil {
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return nil, err
}
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p := &Parser{
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input: l.input,
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pos: -1,
items: l.items,
}
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if op == nil {
op, err = p.parseOp()
} else {
if p.peek(itemObjOpen) {
p.ignore()
}
op.Fields, err = p.parseFields(op.Fields)
}
lexPool.Put(l)
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if err != nil {
return nil, err
}
return op, err
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}
func (p *Parser) next() item {
n := p.pos + 1
if n >= len(p.items) {
p.err = errEOT
return item{typ: itemEOF}
}
p.pos = n
return p.items[p.pos]
}
func (p *Parser) ignore() {
n := p.pos + 1
if n >= len(p.items) {
p.err = errEOT
return
}
p.pos = n
}
func (p *Parser) current() item {
return p.items[p.pos]
}
func (p *Parser) eof() bool {
n := p.pos + 1
return p.items[n].typ == itemEOF
}
func (p *Parser) peek(types ...itemType) bool {
n := p.pos + 1
if p.items[n].typ == itemEOF {
return false
}
if n >= len(p.items) {
return false
}
for i := 0; i < len(types); i++ {
if p.items[n].typ == types[i] {
return true
}
}
return false
}
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func (p *Parser) parseOp() (*Operation, error) {
if !p.peek(itemQuery, itemMutation, itemSub) {
err := errors.New("expecting a query, mutation or subscription")
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return nil, err
}
item := p.next()
op := opPool.Get().(*Operation)
op.Reset()
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switch item.typ {
case itemQuery:
op.Type = opQuery
case itemMutation:
op.Type = opMutate
case itemSub:
op.Type = opSub
}
op.Fields = op.fieldsA[:0]
op.Args = op.argsA[:0]
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var err error
if p.peek(itemName) {
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op.Name = p.val(p.next())
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}
if p.peek(itemArgsOpen) {
p.ignore()
op.Args, err = p.parseArgs(op.Args)
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if err != nil {
return nil, err
}
}
if p.peek(itemObjOpen) {
p.ignore()
op.Fields, err = p.parseFields(op.Fields)
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if err != nil {
return nil, err
}
}
return op, nil
}
func (p *Parser) parseFields(fields []Field) ([]Field, error) {
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st := util.NewStack()
for {
if len(fields) >= maxFields {
return nil, fmt.Errorf("too many fields (max %d)", maxFields)
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}
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if p.peek(itemObjClose) {
p.ignore()
st.Pop()
if st.Len() == 0 {
break
}
continue
}
if p.peek(itemName) == false {
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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)]
f.Args = f.argsA[:0]
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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if f.ID != 0 {
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intf := st.Peek()
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pid, ok := intf.(int32)
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if !ok {
return nil, fmt.Errorf("14: unexpected value %v (%t)", intf, intf)
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}
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f.ParentID = pid
fields[pid].Children = append(fields[pid].Children, f.ID)
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}
if p.peek(itemObjOpen) {
p.ignore()
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st.Push(f.ID)
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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) {
p.ignore()
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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}
}
if p.peek(itemArgsOpen) {
p.ignore()
if f.Args, err = p.parseArgs(f.Args); err != nil {
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return err
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}
}
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return nil
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}
func (p *Parser) parseArgs(args []Arg) ([]Arg, error) {
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var err error
for {
if len(args) >= maxArgs {
return nil, fmt.Errorf("too many args (max %d)", maxArgs)
}
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if p.peek(itemArgsClose) {
p.ignore()
break
}
if p.peek(itemName) == false {
return nil, errors.New("expecting an argument name")
}
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args = append(args, Arg{Name: p.val(p.next())})
arg := &args[(len(args) - 1)]
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if p.peek(itemColon) == false {
return nil, errors.New("missing ':' after argument name")
}
p.ignore()
arg.Val, err = p.parseValue()
if err != nil {
return nil, err
}
}
return args, nil
}
func (p *Parser) parseList() (*Node, error) {
nodes := []*Node{}
parent := nodePool.Get().(*Node)
parent.Reset()
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var ty parserType
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for {
if p.peek(itemListClose) {
p.ignore()
break
}
node, err := p.parseValue()
if err != nil {
return nil, err
}
if ty == 0 {
ty = node.Type
} else {
if ty != node.Type {
return nil, errors.New("All values in a list must be of the same type")
}
}
node.Parent = parent
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nodes = append(nodes, node)
}
if len(nodes) == 0 {
return nil, errors.New("List cannot be empty")
}
parent.Type = nodeList
parent.Children = nodes
return parent, nil
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}
func (p *Parser) parseObj() (*Node, error) {
nodes := []*Node{}
parent := nodePool.Get().(*Node)
parent.Reset()
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for {
if p.peek(itemObjClose) {
p.ignore()
break
}
if p.peek(itemName) == false {
return nil, errors.New("expecting an argument name")
}
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nodeName := p.val(p.next())
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if p.peek(itemColon) == false {
return nil, errors.New("missing ':' after Field argument name")
}
p.ignore()
node, err := p.parseValue()
if err != nil {
return nil, err
}
node.Name = nodeName
node.Parent = parent
nodes = append(nodes, node)
}
parent.Type = nodeObj
parent.Children = nodes
return parent, nil
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}
func (p *Parser) parseValue() (*Node, error) {
if p.peek(itemListOpen) {
p.ignore()
return p.parseList()
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}
if p.peek(itemObjOpen) {
p.ignore()
return p.parseObj()
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}
item := p.next()
node := nodePool.Get().(*Node)
node.Reset()
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switch item.typ {
case itemIntVal:
node.Type = nodeInt
case itemFloatVal:
node.Type = nodeFloat
case itemStringVal:
node.Type = nodeStr
case itemBoolVal:
node.Type = nodeBool
case itemName:
node.Type = nodeStr
case itemVariable:
node.Type = nodeVar
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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node.Val = p.val(item)
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return node, nil
}
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func (p *Parser) val(v item) string {
return b2s(p.input[v.pos:v.end])
}
func b2s(b []byte) string {
return *(*string)(unsafe.Pointer(&b))
}
func (t parserType) String() string {
var v string
switch t {
case parserEOF:
v = "EOF"
case parserError:
v = "error"
case opQuery:
v = "query"
case opMutate:
v = "mutation"
case opSub:
v = "subscription"
case nodeStr:
v = "node-string"
case nodeInt:
v = "node-int"
case nodeFloat:
v = "node-float"
case nodeBool:
v = "node-bool"
case nodeVar:
v = "node-var"
case nodeObj:
v = "node-obj"
case nodeList:
v = "node-list"
}
return fmt.Sprintf("<%s>", v)
}
func FreeNode(n *Node) {
nodePool.Put(n)
}