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parser.go
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parser.go
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package parser
import (
"bufio"
"bytes"
"fmt"
"github.com/rigglo/gql/pkg/language/ast"
"github.com/rigglo/gql/pkg/language/lexer"
)
// Parse parses a gql query
func Parse(query []byte) (lexer.Token, *ast.Document, error) {
tokens := make(chan lexer.Token)
src := bytes.NewReader(query)
readr := bufio.NewReader(src)
go lexer.Lex(readr, tokens)
t, doc, err := parseDocument(tokens)
if err != nil && t.Value == "" {
return t, nil, fmt.Errorf("unexpected EOF")
}
return t, doc, err
}
func parseDocument(tokens chan lexer.Token) (lexer.Token, *ast.Document, error) {
doc := ast.NewDocument()
var err error
token := <-tokens
for {
switch {
case token.Kind == lexer.NameToken && token.Value == "fragment":
f := new(ast.Fragment)
token, f, err = parseFragment(tokens)
if err != nil {
return token, nil, err
}
doc.Fragments = append(doc.Fragments, f)
break
case token.Kind == lexer.NameToken:
op := new(ast.Operation)
token, op, err = parseOperation(token, tokens)
if err != nil {
return token, nil, err
}
doc.Operations = append(doc.Operations, op)
break
case token.Kind == lexer.PunctuatorToken && token.Value == "{":
set := []ast.Selection{}
token, set, err = parseSelectionSet(tokens)
if err != nil {
return token, nil, err
}
doc.Operations = append(doc.Operations, &ast.Operation{
OperationType: ast.Query,
SelectionSet: set,
})
break
case token.Kind == lexer.BadToken && token.Err == nil:
return token, doc, nil
default:
return token, nil, fmt.Errorf("unexpected token: %s", token.Value)
}
}
}
func parseFragment(tokens chan lexer.Token) (lexer.Token, *ast.Fragment, error) {
f := new(ast.Fragment)
var err error
token := <-tokens
if token.Kind == lexer.NameToken && token.Value != "on" {
f.Name = token.Value
} else {
return token, nil, fmt.Errorf("unexpected token: %s", token.Value)
}
token = <-tokens
if token.Kind == lexer.NameToken && token.Value == "on" {
token = <-tokens
if token.Kind == lexer.NameToken {
f.TypeCondition = token.Value
} else {
return token, nil, fmt.Errorf("unexpected token: %s", token.Value)
}
} else {
return token, nil, fmt.Errorf("unexpected token: %s", token.Value)
}
token = <-tokens
if token.Kind == lexer.PunctuatorToken && token.Value == "@" {
ds := []*ast.Directive{}
token, ds, err = parseDirectives(tokens)
if err != nil {
return token, nil, err
}
f.Directives = ds
}
if token.Kind == lexer.PunctuatorToken && token.Value == "{" {
sSet := []ast.Selection{}
token, sSet, err = parseSelectionSet(tokens)
if err != nil {
return token, nil, err
}
f.SelectionSet = sSet
} else {
return token, nil, fmt.Errorf("unexpected token: %s", token.Value)
}
return token, f, nil
}
func parseOperation(token lexer.Token, tokens chan lexer.Token) (lexer.Token, *ast.Operation, error) {
var err error
if token.Kind != lexer.NameToken {
return token, nil, fmt.Errorf("unexpected token: %s", token.Value)
}
var ot ast.OperationType
if token.Value == "query" {
ot = ast.Query
} else if token.Value == "mutation" {
ot = ast.Mutation
} else if token.Value == "subscription" {
ot = ast.Subscription
} else {
return token, nil, fmt.Errorf("invalid token value: %s, wanted one of 'query', 'mutation' or 'subscription'", token.Value)
}
op := ast.NewOperation(ot)
token = <-tokens
for {
switch {
case token.Kind == lexer.NameToken:
op.Name = token.Value
token = <-tokens
break
case token.Kind == lexer.PunctuatorToken && token.Value == "(":
vs := []*ast.Variable{}
token, vs, err = parseVariables(tokens)
if err != nil {
return token, nil, err
}
op.Variables = vs
break
case token.Kind == lexer.PunctuatorToken && token.Value == "@":
ds := []*ast.Directive{}
var err error
token, ds, err = parseDirectives(tokens)
if err != nil {
return token, nil, err
}
op.Directives = ds
break
case token.Kind == lexer.PunctuatorToken && token.Value == "{":
sSet := []ast.Selection{}
token, sSet, err = parseSelectionSet(tokens)
if err != nil {
return token, nil, err
}
op.SelectionSet = sSet
return token, op, nil
default:
return token, nil, fmt.Errorf("invalid token value: %s", token.Value)
}
}
}
func parseVariables(tokens chan lexer.Token) (lexer.Token, []*ast.Variable, error) {
token := <-tokens
vs := []*ast.Variable{}
var err error
for {
if token.Kind == lexer.PunctuatorToken && token.Value == ")" {
return <-tokens, vs, nil
}
v := new(ast.Variable)
v.Location.Column = token.Col
v.Location.Line = token.Line - 1
if token.Kind == lexer.PunctuatorToken && token.Value == "$" {
token = <-tokens
if token.Kind == lexer.NameToken {
v.Name = token.Value
} else {
return token, nil, fmt.Errorf("unexpected token: %s", token.Value)
}
} else {
return token, nil, fmt.Errorf("unexpected token: %s", token.Value)
}
token = <-tokens
if token.Kind == lexer.PunctuatorToken && token.Value == ":" {
token = <-tokens
} else {
return token, nil, fmt.Errorf("unexpected token: %s", token.Value)
}
var t ast.Type
token, t, err = parseType(token, tokens)
if err != nil {
return token, nil, err
}
v.Type = t
if token.Kind == lexer.PunctuatorToken && token.Value == "=" {
var dv ast.Value
token, dv, err = parseValue(<-tokens, tokens)
if err != nil {
return token, nil, err
}
v.DefaultValue = dv
}
if token.Kind == lexer.PunctuatorToken && token.Value == "$" {
vs = append(vs, v)
continue
} else if token.Kind == lexer.PunctuatorToken && token.Value == ")" {
vs = append(vs, v)
return <-tokens, vs, nil
}
}
}
func parseType(token lexer.Token, tokens chan lexer.Token) (lexer.Token, ast.Type, error) {
switch {
case token.Kind == lexer.NameToken:
nt := new(ast.NamedType)
nt.Name = token.Value
nt.Location.Column = token.Col
nt.Location.Line = token.Line - 1
token = <-tokens
if token.Kind == lexer.PunctuatorToken && token.Value == "!" {
nnt := new(ast.NonNullType)
nnt.Type = nt
nnt.Location.Column = token.Col
nnt.Location.Line = token.Line - 1
return <-tokens, nnt, nil
}
return token, nt, nil
case token.Kind == lexer.PunctuatorToken && token.Value == "[":
token = <-tokens
var (
t ast.Type
err error
)
loc := ast.Location{
Column: token.Col,
Line: token.Line,
}
token, t, err = parseType(token, tokens)
if err != nil {
return token, nil, err
}
if token.Kind == lexer.PunctuatorToken && token.Value == "]" {
token = <-tokens
} else {
return token, nil, fmt.Errorf("unexpected token: %s", token.Value)
}
lt := &ast.ListType{
Type: t,
Location: loc,
}
if token.Kind == lexer.PunctuatorToken && token.Value == "!" {
return <-tokens, &ast.NonNullType{
Type: lt,
}, nil
}
return token, lt, nil
default:
return token, nil, fmt.Errorf("unexpected token: %s", token.Value)
}
}
func parseSelectionSet(tokens chan lexer.Token) (token lexer.Token, set []ast.Selection, err error) {
end := false
token = <-tokens
for {
switch {
case token.Kind == lexer.PunctuatorToken && token.Value == "...":
var sel ast.Selection
token, sel, err = parseFragments(tokens)
if err != nil {
return token, nil, err
}
set = append(set, sel)
break
case token.Kind == lexer.NameToken:
f := new(ast.Field)
token, f, err = parseField(token, tokens)
if err != nil {
return token, nil, err
}
set = append(set, f)
break
case token.Kind == lexer.PunctuatorToken && token.Value == "}":
end = true
break
default:
return token, nil, fmt.Errorf("unexpected token: %s", token.Value)
}
if end {
break
}
}
return <-tokens, set, nil
}
func parseField(token lexer.Token, tokens chan lexer.Token) (lexer.Token, *ast.Field, error) {
var err error
f := new(ast.Field)
f.Alias = token.Value
f.Location.Column = token.Col
f.Location.Line = token.Line - 1
defer func() {
if f.Name == "" {
f.Name = f.Alias
}
}()
end := false
token = <-tokens
for {
switch {
case token.Kind == lexer.PunctuatorToken && token.Value == ":" && f.Name == "":
token = <-tokens
if token.Kind == lexer.NameToken {
f.Name = token.Value
} else {
return token, nil, fmt.Errorf("unexpected token, expected name token, got: %s", token.Value)
}
token = <-tokens
break
case token.Kind == lexer.PunctuatorToken && token.Value == "(":
args, err := parseArguments(tokens)
if err != nil {
return <-tokens, nil, err
}
f.Arguments = args
token = <-tokens
break
case token.Kind == lexer.PunctuatorToken && token.Value == "@":
ds := []*ast.Directive{}
var err error
token, ds, err = parseDirectives(tokens)
if err != nil {
return token, nil, err
}
f.Directives = ds
case token.Kind == lexer.PunctuatorToken && token.Value == "{":
sSet := []ast.Selection{}
token, sSet, err = parseSelectionSet(tokens)
if err != nil {
return token, nil, err
}
f.SelectionSet = sSet
return token, f, nil
case token.Kind == lexer.NameToken:
return token, f, nil
case token.Kind == lexer.PunctuatorToken && token.Value == "}":
return token, f, nil
default:
if f.Alias != "" {
return token, f, nil
}
return token, nil, fmt.Errorf("invalid token: '%s'", token.Value)
}
if end {
break
}
}
return token, f, nil
}
func parseArguments(tokens chan lexer.Token) (args []*ast.Argument, err error) {
token := <-tokens
for {
arg := new(ast.Argument)
if token.Kind == lexer.NameToken {
arg.Name = token.Value
} else {
return nil, fmt.Errorf("unexpected token args: %+v", token.Value)
}
token = <-tokens
if token.Kind != lexer.PunctuatorToken && token.Value != ":" {
return nil, fmt.Errorf("unexpected token, expected ':'")
}
token = <-tokens
var val ast.Value
token, val, err = parseValue(token, tokens)
if err != nil {
return nil, err
}
arg.Value = val
args = append(args, arg)
if token.Kind == lexer.PunctuatorToken && token.Value == ")" {
return args, nil
}
}
}
func parseValue(token lexer.Token, tokens chan lexer.Token) (lexer.Token, ast.Value, error) {
switch {
case token.Kind == lexer.PunctuatorToken && token.Value == "$":
v := new(ast.VariableValue)
v.Location.Column = token.Col
v.Location.Line = token.Line - 1
token = <-tokens
if token.Kind != lexer.NameToken {
return token, nil, fmt.Errorf("invalid token")
}
v.Name = token.Value
return <-tokens, v, nil
case token.Kind == lexer.IntValueToken:
v := new(ast.IntValue)
v.Value = token.Value
v.Location.Column = token.Col
v.Location.Line = token.Line - 1
return <-tokens, v, nil
case token.Kind == lexer.FloatValueToken:
v := new(ast.FloatValue)
v.Value = token.Value
v.Location.Column = token.Col
v.Location.Line = token.Line - 1
return <-tokens, v, nil
case token.Kind == lexer.StringValueToken:
v := new(ast.StringValue)
v.Value = token.Value
v.Location.Column = token.Col
v.Location.Line = token.Line - 1
return <-tokens, v, nil
case token.Kind == lexer.NameToken && (token.Value == "false" || token.Value == "true"):
v := new(ast.BooleanValue)
v.Value = token.Value
v.Location.Column = token.Col
v.Location.Line = token.Line - 1
return <-tokens, v, nil
case token.Kind == lexer.NameToken && token.Value == "null":
v := new(ast.NullValue)
v.Value = token.Value
v.Location.Column = token.Col
v.Location.Line = token.Line - 1
return <-tokens, v, nil
case token.Kind == lexer.NameToken:
v := new(ast.EnumValue)
v.Value = token.Value
v.Location.Column = token.Col
v.Location.Line = token.Line - 1
return <-tokens, v, nil
case token.Kind == lexer.PunctuatorToken && token.Value == "[":
return parseListValue(tokens)
case token.Kind == lexer.PunctuatorToken && token.Value == "{":
return parseObjectValue(tokens)
}
return token, nil, fmt.Errorf("unexpected token: %s", token.Value)
}
func parseListValue(tokens chan lexer.Token) (lexer.Token, *ast.ListValue, error) {
list := new(ast.ListValue)
token := <-tokens
for {
if token.Kind == lexer.PunctuatorToken && token.Value == "]" {
return <-tokens, list, nil
}
var (
err error
v ast.Value
)
token, v, err = parseValue(token, tokens)
if err != nil {
return token, nil, err
}
list.Values = append(list.Values, v)
}
}
func parseObjectValue(tokens chan lexer.Token) (lexer.Token, *ast.ObjectValue, error) {
token := <-tokens
var err error
o := new(ast.ObjectValue)
o.Fields = []*ast.ObjectFieldValue{}
for {
field := new(ast.ObjectFieldValue)
field.Location.Column = token.Col
field.Location.Line = token.Line - 1
if token.Kind == lexer.NameToken {
field.Name = token.Value
} else {
return token, nil, fmt.Errorf("unexpected token: %s", token.Value)
}
token = <-tokens
if token.Kind != lexer.PunctuatorToken && token.Value != ":" {
return token, nil, fmt.Errorf("unexpected token: %s", token.Value)
}
token = <-tokens
var val ast.Value
token, val, err = parseValue(token, tokens)
if err != nil {
return token, nil, err
}
field.Value = val
o.Fields = append(o.Fields, field)
if token.Kind == lexer.PunctuatorToken && token.Value == "}" {
return <-tokens, o, nil
}
}
}
func parseFragments(tokens chan lexer.Token) (token lexer.Token, sel ast.Selection, err error) {
token = <-tokens
if token.Kind == lexer.NameToken && token.Value == "on" {
inf := new(ast.InlineFragment)
token = <-tokens
if token.Kind == lexer.NameToken {
inf.TypeCondition = token.Value
token = <-tokens
}
if token.Kind == lexer.PunctuatorToken && token.Value == "@" {
ds := []*ast.Directive{}
token, ds, err = parseDirectives(tokens)
if err != nil {
return token, nil, err
}
inf.Directives = ds
}
if token.Kind == lexer.PunctuatorToken && token.Value == "{" {
sSet := []ast.Selection{}
token, sSet, err = parseSelectionSet(tokens)
if err != nil {
return token, nil, err
}
inf.SelectionSet = sSet
} else {
return token, nil, fmt.Errorf("unexpected token: %s", token.Value)
}
return token, inf, nil
} else if token.Kind == lexer.PunctuatorToken && token.Value == "{" {
sSet := []ast.Selection{}
loc := ast.Location{
Line: token.Line,
Column: token.Col,
}
token, sSet, err = parseSelectionSet(tokens)
if err != nil {
return token, nil, err
}
inf := &ast.InlineFragment{
SelectionSet: sSet,
Location: loc,
}
return token, inf, nil
} else if token.Kind == lexer.NameToken && token.Value != "on" {
fs := new(ast.FragmentSpread)
fs.Name = token.Value
fs.Location.Column = token.Col
fs.Location.Line = token.Line - 1
token = <-tokens
if token.Kind == lexer.PunctuatorToken && token.Value == "@" {
ds := []*ast.Directive{}
token, ds, err = parseDirectives(tokens)
if err != nil {
return token, nil, err
}
fs.Directives = ds
}
return token, fs, nil
}
return token, nil, fmt.Errorf("unexpected token: %s", token.Value)
}
func parseDirectives(tokens chan lexer.Token) (lexer.Token, []*ast.Directive, error) {
token := <-tokens
ds := []*ast.Directive{}
for {
if token.Kind == lexer.NameToken {
d := new(ast.Directive)
d.Name = token.Value
d.Location.Column = token.Col
d.Location.Line = token.Line - 1
token = <-tokens
if token.Kind == lexer.PunctuatorToken && token.Value == "(" {
args, err := parseArguments(tokens)
if err != nil {
return token, nil, err
}
d.Arguments = args
token = <-tokens
}
ds = append(ds, d)
if token.Kind == lexer.PunctuatorToken && token.Value == "@" {
token = <-tokens
} else {
return token, ds, nil
}
} else {
return token, ds, nil
}
}
}