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parse.go
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parse.go
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//go:generate stringer -type=ParserType,FieldType -output=./gen_string.go
package graph
import (
"errors"
"fmt"
"sync"
"unsafe"
)
var (
errEOT = errors.New("end of tokens")
)
const (
maxFields = 1200
maxArgs = 25
)
type ParserType int8
const (
parserError ParserType = iota
parserEOF
OpQuery
OpMutate
OpSub
NodeStr
NodeNum
NodeBool
NodeObj
NodeList
NodeVar
)
type FieldType int8
const (
FieldUnion FieldType = iota + 1
FieldMember
FieldKeyword
)
type Operation struct {
Type ParserType
Name string
Args []Arg
argsA [10]Arg
Directives []Directive
Fields []Field
fieldsA [10]Field
}
type Fragment struct {
Name string
On string
Fields []Field
}
type Field struct {
ID int32
ParentID int32
Type FieldType
Name string
Alias string
Args []Arg
argsA [5]Arg
Directives []Directive
Children []int32
childrenA [5]int32
}
type Arg struct {
Name string
Val *Node
}
type Directive struct {
Name string
Args []Arg
}
type Node struct {
Type ParserType
Name string
Val string
Parent *Node
Children []*Node
}
var nodePool = sync.Pool{
New: func() interface{} { return new(Node) },
}
var zeroNode = Node{}
func (n *Node) Reset() {
*n = zeroNode
}
func (n *Node) Free() {
nodePool.Put(n)
}
type Parser struct {
frags map[string]Fragment
fetchFrag func(name string) (string, error)
input []byte // the string being scanned
pos int
items []item
json bool
err error
}
func Parse(gql []byte, fetchFrag func(name string) (string, error)) (Operation, error) {
var l lexer
var op Operation
var err error
if len(gql) == 0 {
return op, errors.New("empty query")
}
if l, err = lex(gql); err != nil {
return op, err
}
p := Parser{
fetchFrag: fetchFrag,
input: l.input,
pos: -1,
items: l.items,
}
op.Fields = op.fieldsA[:0]
s := -1
qf := false
for {
if p.peek(itemEOF) {
p.ignore()
break
}
if p.peek(itemFragment) && p.fetchFrag == nil {
p.ignore()
if _, err := p.parseFragment(); err != nil {
return op, err
}
} else {
if !qf && p.peek(itemQuery, itemMutation, itemSub, itemObjOpen) {
s = p.pos
qf = true
}
p.ignore()
}
}
p.reset(s)
if op, err = p.parseOp(); err != nil {
return op, err
}
for i, f := range op.Fields {
if f.ParentID == -1 && len(f.Args) == 0 && len(f.Children) == 0 {
op.Fields[i].Type = FieldKeyword
}
}
return op, nil
}
func (p *Parser) parseFragment() (Fragment, error) {
var err error
var frag Fragment
if p.peek(itemName) {
frag.Name = p.val(p.next())
} else {
return frag, errors.New("fragment: missing name")
}
if p.peek(itemOn) {
p.ignore()
} else {
return frag, errors.New("fragment: missing 'on' keyword")
}
if p.peek(itemName) {
frag.On = p.vall(p.next())
} else {
return frag, errors.New("fragment: missing table name after 'on' keyword")
}
if p.peek(itemObjOpen) {
p.ignore()
} else {
return frag, fmt.Errorf("fragment: expecting a '{', got: %s", p.next())
}
frag.Fields, err = p.parseFields(frag.Fields)
if err != nil {
return frag, fmt.Errorf("fragment: %v", err)
}
if p.frags == nil {
p.frags = make(map[string]Fragment)
}
p.frags[frag.Name] = frag
return frag, nil
}
func (p *Parser) parseOp() (Operation, error) {
var err error
var typeSet bool
var op Operation
if p.peek(itemQuery, itemMutation, itemSub) {
if err = p.parseOpTypeAndArgs(&op); err != nil {
return op, fmt.Errorf("%s: %v", op.Type, err)
}
typeSet = true
}
if p.peek(itemObjOpen) {
p.ignore()
if !typeSet {
op.Type = OpQuery
}
for {
if p.peek(itemEOF, itemFragment) {
p.ignore()
break
}
op.Fields, err = p.parseFields(op.Fields)
if err != nil {
return op, fmt.Errorf("%s: %v", op.Type, err)
}
}
} else {
return op, fmt.Errorf("expecting a query, mutation or subscription, got: %s", p.next())
}
return op, nil
}
func (p *Parser) parseOpTypeAndArgs(op *Operation) error {
item := p.next()
switch item._type {
case itemQuery:
op.Type = OpQuery
case itemMutation:
op.Type = OpMutate
case itemSub:
op.Type = OpSub
}
op.Args = op.argsA[:0]
var err error
if p.peek(itemName) {
op.Name = p.val(p.next())
}
for p.peek(itemDirective) {
p.ignore()
if op.Directives, err = p.parseDirective(op.Directives); err != nil {
return err
}
}
if p.peek(itemArgsOpen) {
p.ignore()
op.Args, err = p.parseOpParams(op.Args)
if err != nil {
return err
}
}
return nil
}
func ParseArgValue(argVal string, json bool) (*Node, error) {
if argVal == "" {
return nil, errors.New("empty value")
}
l, err := lex([]byte(argVal))
if err != nil {
return nil, err
}
p := Parser{
input: l.input,
pos: -1,
items: l.items,
json: json,
}
return p.parseValue()
}
func ParseFragment(fragment string, fetchFrag func(name string) (string, error)) (
Fragment, error) {
var f Fragment
var err error
l, err := lex([]byte(fragment))
if err != nil {
return f, err
}
p := Parser{
fetchFrag: fetchFrag,
input: l.input,
pos: -1,
items: l.items,
}
if p.peek(itemFragment) {
p.ignore()
f, err = p.parseFragment()
}
return f, err
}
func (p *Parser) parseFields(fields []Field) ([]Field, error) {
var err error
st := NewStack()
if !p.peek(itemName, itemSpread) {
return nil, fmt.Errorf("unexpected token: %s", p.peekNext())
}
for {
if p.peek(itemEOF) {
p.ignore()
return nil, errors.New("invalid query")
}
if p.peek(itemObjClose) {
p.ignore()
if st.Len() != 0 {
st.Pop()
continue
} else {
break
}
}
if len(fields) >= maxFields {
return nil, fmt.Errorf("too many fields (max %d)", maxFields)
}
isFrag := false
if p.peek(itemSpread) {
p.ignore()
isFrag = true
}
if isFrag {
fields, err = p.parseFragmentFields(st, fields)
} else {
fields, err = p.parseNormalFields(st, fields)
}
if err != nil {
return nil, err
}
}
return fields, nil
}
func (p *Parser) parseNormalFields(st *Stack, fields []Field) ([]Field, error) {
if !p.peek(itemName) {
return nil, fmt.Errorf("expecting an alias or field name, got: %s", p.next())
}
fields = append(fields, Field{ID: int32(len(fields))})
f := &fields[(len(fields) - 1)]
f.Args = f.argsA[:0]
f.Children = f.childrenA[:0]
// Parse the field
if err := p.parseField(f); err != nil {
return nil, err
}
if st.Len() == 0 {
f.ParentID = -1
} else {
pid := st.Peek()
f.ParentID = pid
fields[pid].Children = append(fields[pid].Children, f.ID)
}
// The first opening curley brackets after this
// comes the columns or child fields
if p.peek(itemObjOpen) {
p.ignore()
st.Push(f.ID)
}
return fields, nil
}
func (p *Parser) parseFragmentFields(st *Stack, fields []Field) ([]Field, error) {
var err error
var fr Fragment
var ok bool
pid := st.Peek()
if p.peek(itemOn) {
p.ignore()
fields[pid].Type = FieldUnion
if fields, err = p.parseNormalFields(st, fields); err != nil {
return nil, err
}
// If parent is a union selector than copy over args from the parent
// to the first child which is the root selector for each union type.
for i := pid + 1; i < int32(len(fields)); i++ {
f := &fields[i]
if f.ParentID == pid {
f.Args = fields[pid].Args
f.Type = FieldMember
}
}
} else {
if !p.peek(itemName) {
return nil, fmt.Errorf("expecting a fragment name, got: %s", p.next())
}
name := p.val(p.next())
fr, ok = p.frags[name]
if !ok {
if p.fetchFrag != nil {
fval, err := p.fetchFrag(name)
if err != nil {
return nil, fmt.Errorf("fragment not found: %s", name)
}
if fr, err = ParseFragment(fval, p.fetchFrag); err != nil {
return nil, err
}
} else {
return nil, fmt.Errorf("fragment not defined: %s", name)
}
}
ff := fr.Fields
n := int32(len(fields))
fields = append(fields, ff...)
for i := 0; i < len(ff); i++ {
k := (n + int32(i))
f := &fields[k]
f.ID = int32(k)
// Nothing to do here if fields was originally empty
if n != 0 {
// If this is the top-level, point the parent to the parent of the
// previous field.
if f.ParentID == -1 {
if pid != -1 {
f.ParentID = pid
fields[pid].Children = append(fields[pid].Children, f.ID)
}
// Update all the other parents id's by our new place in this new array
} else {
f.ParentID += n
}
}
// Copy over children since fields append is not a deep copy
f.Children = make([]int32, len(f.Children))
copy(f.Children, ff[i].Children)
// Copy over args since args append is not a deep copy
f.Args = make([]Arg, len(f.Args))
copy(f.Args, ff[i].Args)
// Update all the children which is needed.
for j := range f.Children {
f.Children[j] += n
}
}
}
return fields, nil
}
func (p *Parser) parseField(f *Field) error {
var err error
v := p.next()
if p.peek(itemColon) {
p.ignore()
if p.peek(itemName) {
f.Alias = p.val(v)
f.Name = p.val(p.next())
} else {
return errors.New("expecting an aliased field name")
}
} else {
f.Name = p.val(v)
}
if p.peek(itemArgsOpen) {
p.ignore()
if f.Args, err = p.parseArgs(f.Args); err != nil {
return err
}
}
for p.peek(itemDirective) {
p.ignore()
if f.Directives, err = p.parseDirective(f.Directives); err != nil {
return err
}
}
return nil
}
func (p *Parser) parseOpParams(args []Arg) ([]Arg, error) {
for {
if len(args) >= maxArgs {
return nil, fmt.Errorf("too many args (max %d)", maxArgs)
}
if p.peek(itemEOF, itemArgsClose) {
p.ignore()
break
}
p.next()
}
return args, nil
}
func (p *Parser) parseArgs(args []Arg) ([]Arg, error) {
var err error
var argNameTypes []MType
if p.json {
argNameTypes = []MType{itemName, itemStringVal}
} else {
argNameTypes = []MType{itemName}
}
for {
if len(args) >= maxArgs {
return nil, fmt.Errorf("too many args (max %d)", maxArgs)
}
if p.peek(itemEOF, itemArgsClose) {
p.ignore()
break
}
if !p.peek(argNameTypes...) {
return nil, fmt.Errorf("expecting an argument name got: %s", p.peekNext())
}
args = append(args, Arg{Name: p.val(p.next())})
arg := &args[(len(args) - 1)]
if !p.peek(itemColon) {
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) parseDirective(dirs []Directive) ([]Directive, error) {
var err error
var d Directive
if p.peek(itemName) {
d.Name = p.vall(p.next())
} else {
return nil, fmt.Errorf("expecting directive name after @ symbol got: %s", p.peekNext())
}
if p.peek(itemArgsOpen) {
p.ignore()
if d.Args, err = p.parseArgs(d.Args); err != nil {
return nil, err
}
}
return append(dirs, d), nil
}
func (p *Parser) parseList() (*Node, error) {
nodes := []*Node{}
parent := nodePool.Get().(*Node)
parent.Reset()
var ty ParserType
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
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
}
func (p *Parser) parseObj() (*Node, error) {
nodes := []*Node{}
parent := nodePool.Get().(*Node)
parent.Reset()
var argNameTypes []MType
if p.json {
argNameTypes = []MType{itemName, itemStringVal}
} else {
argNameTypes = []MType{itemName}
}
for {
if p.peek(itemEOF, itemObjClose) {
p.ignore()
break
}
if !p.peek(argNameTypes...) {
return nil, errors.New("expecting an argument name")
}
nodeName := p.val(p.next())
if !p.peek(itemColon) {
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
}
func (p *Parser) parseValue() (*Node, error) {
if p.peek(itemListOpen) {
p.ignore()
return p.parseList()
}
if p.peek(itemObjOpen) {
p.ignore()
return p.parseObj()
}
item := p.next()
node := nodePool.Get().(*Node)
node.Reset()
switch item._type {
case itemNumberVal:
node.Type = NodeNum
case itemStringVal:
node.Type = NodeStr
case itemBoolVal:
node.Type = NodeBool
case itemName:
node.Type = NodeStr
case itemVariable:
node.Type = NodeVar
default:
return nil, fmt.Errorf("expecting a number, string, object, list or variable as an argument value (not %s)", p.val(p.next()))
}
node.Val = p.val(item)
return node, nil
}
func (p *Parser) val(v item) string {
return b2s(v.val)
}
func (p *Parser) vall(v item) string {
lowercase(v.val)
return b2s(v.val)
}
func (p *Parser) peek(types ...MType) bool {
n := p.pos + 1
l := len(types)
// if p.items[n]._type == itemEOF {
// return false
// }
if n >= len(p.items) {
return types[0] == itemEOF
}
if l == 1 {
return p.items[n]._type == types[0]
}
for i := 0; i < l; i++ {
if p.items[n]._type == types[i] {
return true
}
}
return false
}
func (p *Parser) next() item {
n := p.pos + 1
if n >= len(p.items) {
p.err = errEOT
return item{_type: 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) peekNext() string {
item := p.items[p.pos+1]
return b2s(item.val)
}
func (p *Parser) reset(to int) {
p.pos = to
}
func b2s(b []byte) string {
return *(*string)(unsafe.Pointer(&b))
}
func FreeNode(n *Node) {
nodePool.Put(n)
}