func lexText(l *lex.Lexer) lex.StateFn {
Loop:
for {
switch r := l.Next(); {
case r == leftCurl:
l.Backup()
l.Emit(itemText) // emit whatever we have so far.
l.Next() // advance one to get back to where we saw leftCurl.
l.Depth += 1 // one level down.
l.Emit(itemLeftCurl)
return lexInside // we're in.
case r == rightCurl:
return l.Errorf("Too many right characters")
case r == lex.EOF:
break Loop
case isNameBegin(r):
l.Backup()
l.Emit(itemText)
return lexOperationType
}
}
if l.Pos > l.Start {
l.Emit(itemText)
}
l.Emit(lex.ItemEOF)
return nil
}
// lexInsideMutation lexes the text inside a mutation block.
func lexInsideMutation(l *lex.Lexer) lex.StateFn {
for {
switch r := l.Next(); {
case r == rightCurl:
l.Depth--
l.Emit(itemRightCurl)
if l.Depth == 0 {
return lexText
}
case r == leftCurl:
l.Depth++
l.Emit(itemLeftCurl)
if l.Depth >= 2 {
return lexTextMutation
}
case r == lex.EOF:
return l.Errorf("Unclosed mutation action")
case isSpace(r) || isEndOfLine(r):
l.Ignore()
case isNameBegin(r):
return lexNameMutation
default:
return l.Errorf("Unrecognized character in lexInsideMutation: %#U", r)
}
}
}
// lexDirective is called right after we see a @.
func lexDirective(l *lex.Lexer) lex.StateFn {
r := l.Next()
if !isNameBegin(r) {
return l.Errorf("Unrecognized character in lexDirective: %#U", r)
}
l.Backup()
// This gives our buffer an initial capacity. Its length is zero though. The
// buffer can grow beyond this initial capacity.
buf := bytes.NewBuffer(make([]byte, 0, 15))
for {
// The caller already checked isNameBegin, and absorbed one rune.
r = l.Next()
buf.WriteRune(r)
if isNameSuffix(r) {
continue
}
l.Backup()
l.Emit(itemDirectiveName)
directive := buf.Bytes()[:buf.Len()-1]
// The lexer may behave differently for different directives. Hence, we need
// to check the directive here and go into the right state.
if string(directive) == "filter" {
return lexFilterInside
}
return l.Errorf("Unhandled directive %s", directive)
}
return lexInside
}
// Assumes '"' has already been encountered.
func lexLiteral(l *lex.Lexer) lex.StateFn {
for {
r := l.Next()
if r == '\u005c' { // backslash
r = l.Next()
continue // This would skip over the escaped rune.
}
if r == lex.EOF || isEndLiteral(r) {
break
}
}
l.Backup()
l.Emit(itemLiteral)
l.Next() // Move to end literal.
l.Ignore() // Ignore end literal.
l.Depth++
r := l.Peek()
if r == '@' {
return lexLanguage(l)
}
if r == '^' {
return lexObjectType(l)
}
return lexText
}
// lexTextMutation lexes and absorbs the text inside a mutation operation block.
func lexTextMutation(l *lex.Lexer) lex.StateFn {
for {
r := l.Next()
if r == lex.EOF {
return l.Errorf("Unclosed mutation text")
}
if r == quote {
return lexMutationValue
}
if r == leftCurl {
l.Depth++
}
if r == rightCurl {
if l.Depth > 2 {
l.Depth--
continue
}
}
if r != rightCurl {
// Absorb everything until we find '}'.
continue
}
l.Backup()
l.Emit(itemMutationContent)
break
}
return lexInsideMutation
}
func lexObject(l *lex.Lexer) lex.StateFn {
for {
switch r := l.Next(); {
case r == rightCurl:
return lexText
case isSpace(r) || isEndOfLine(r):
l.Ignore()
case isNameBegin(r):
{
for {
r := l.Next()
if isNameSuffix(r) {
continue // absorb
}
l.Backup()
l.Emit(itemObject)
break
}
return lexObjectBlock
}
default:
return l.Errorf("Invalid schema. Unexpected %s", l.Input[l.Start:l.Pos])
}
}
}
func lexFragmentSpread(l *lex.Lexer) lex.StateFn {
for {
r := l.Next()
if isNameSuffix(r) {
continue
}
l.Backup()
l.Emit(itemFragmentSpread)
break
}
return lexInside
}
// lexArgName lexes and emits the name part of an argument.
func lexArgName(l *lex.Lexer) lex.StateFn {
for {
r := l.Next()
if isNameSuffix(r) {
continue
}
l.Backup()
l.Emit(itemArgName)
break
}
return lexArgInside
}
// lexInside lexes the content inside a query block.
func lexInside(l *lex.Lexer) lex.StateFn {
for {
switch r := l.Next(); {
case r == period:
if l.Next() == period && l.Next() == period {
return lexFragmentSpread
}
// We do not expect a period at all. If you do, you may want to
// backup the two extra periods we try to read.
return l.Errorf("Unrecognized character in lexInside: %#U", r)
case r == rightCurl:
l.Depth--
l.Emit(itemRightCurl)
if l.Depth == 0 {
return lexText
}
case r == leftCurl:
l.Depth++
l.Emit(itemLeftCurl)
case r == lex.EOF:
return l.Errorf("Unclosed action")
case isSpace(r) || isEndOfLine(r) || r == comma:
l.Ignore()
case isNameBegin(r):
return lexName
case r == '#':
l.Backup()
return lexComment
case r == leftRound:
l.Emit(itemLeftRound)
l.AcceptRun(isSpace)
l.Ignore()
k := l.Next()
if k == '_' || l.Depth != 1 || l.Mode == fragmentMode {
l.Backup()
l.Emit(itemArgument)
return lexArgInside
}
// This is a generator function.
l.Backup()
l.Emit(itemGenerator)
l.FilterDepth++
return lexFilterInside
case r == ':':
return lexAlias
case r == '@':
return lexDirective
default:
return l.Errorf("Unrecognized character in lexInside: %#U", r)
}
}
}
// lexFilterFuncName expects input to look like equal("...", "...").
func lexFilterFuncName(l *lex.Lexer) lex.StateFn {
for {
// The caller already checked isNameBegin, and absorbed one rune.
r := l.Next()
if isNameSuffix(r) {
continue
}
l.Backup()
l.Emit(itemFilterFunc)
break
}
return lexFilterFuncInside
}
// lexNameMutation lexes the itemMutationOp, which could be set or delete.
func lexNameMutation(l *lex.Lexer) lex.StateFn {
for {
// The caller already checked isNameBegin, and absorbed one rune.
r := l.Next()
if isNameBegin(r) {
continue
}
l.Backup()
l.Emit(itemMutationOp)
break
}
return lexInsideMutation
}
func lexAlias(l *lex.Lexer) lex.StateFn {
l.AcceptRun(isSpace)
l.Ignore() // Any spaces encountered.
for {
r := l.Next()
if isNameSuffix(r) {
continue
}
l.Backup()
l.Emit(itemAlias)
break
}
return lexInside
}
func lexLanguage(l *lex.Lexer) lex.StateFn {
r := l.Next()
if r != '@' {
return l.Errorf("Expected @ prefix for lexLanguage")
}
l.Ignore()
r = l.Next()
if !isLangTagPrefix(r) {
return l.Errorf("Invalid language tag prefix: %v", r)
}
l.AcceptRun(isLangTag)
l.Emit(itemLanguage)
return lexText
}
func lexUntilClosing(l *lex.Lexer, styp lex.ItemType,
sfn lex.StateFn) lex.StateFn {
l.AcceptUntil(isClosingBracket)
r := l.Next()
if r == lex.EOF {
return l.Errorf("Unexpected end of subject")
}
if r == '>' {
l.Emit(styp)
return sfn
}
return l.Errorf("Invalid character %v found for itemType: %v", r, styp)
}
func lexOperationType(l *lex.Lexer) lex.StateFn {
for {
r := l.Next()
if isNameSuffix(r) {
continue // absorb
}
l.Backup()
word := l.Input[l.Start:l.Pos]
if word == "query" || word == "mutation" {
l.Emit(itemOpType)
}
break
}
return lexText
}
// lexArgVal lexes and emits the value part of an argument.
func lexArgVal(l *lex.Lexer) lex.StateFn {
l.AcceptRun(isSpace)
l.Ignore() // Any spaces encountered.
for {
r := l.Next()
if isSpace(r) || isEndOfLine(r) || r == rightRound || r == comma {
l.Backup()
l.Emit(itemArgVal)
return lexArgInside
}
if r == lex.EOF {
return l.Errorf("Reached lex.EOF while reading var value: %v",
l.Input[l.Start:l.Pos])
}
}
}
func lexScalarBlock(l *lex.Lexer) lex.StateFn {
for {
switch r := l.Next(); {
case r == ')':
l.Emit(itemRightRound)
return lexText
case isNameBegin(r):
l.Backup()
return lexScalarPair1
case isSpace(r) || isEndOfLine(r):
l.Ignore()
default:
return l.Errorf("Invalid schema. Unexpected %s", l.Input[l.Start:l.Pos])
}
}
}
func lexObjectBlock(l *lex.Lexer) lex.StateFn {
for {
switch r := l.Next(); {
case r == leftCurl:
l.Emit(itemLeftCurl)
case isSpace(r) || isEndOfLine(r):
l.Ignore()
case r == rightCurl:
l.Emit(itemRightCurl)
return lexText
case isNameBegin(r):
return lexObjectPair
default:
return l.Errorf("Invalid schema. Unexpected %s", l.Input[l.Start:l.Pos])
}
}
}
func lexArgVal(l *lex.Lexer) lex.StateFn {
l.AcceptRun(isSpace)
l.Ignore() // Any spaces encountered.
for {
r := l.Next()
if isSpace(r) || isEndOfLine(r) || r == ')' || r == ',' {
l.Backup()
l.Emit(itemArgVal)
return lexArgInside
}
if r == lex.EOF {
return l.Errorf("Reached lex.EOF while reading var value: %v",
l.Input[l.Start:l.Pos])
}
}
glog.Fatal("This shouldn't be reached.")
return nil
}
// Assumes that the current rune is '_'.
func lexBlankNode(l *lex.Lexer, styp lex.ItemType,
sfn lex.StateFn) lex.StateFn {
// RDF Blank Node.
// TODO: At some point do checkings based on the guidelines. For now,
// just accept everything until space.
l.AcceptUntil(isSpace)
r := l.Peek()
if r == lex.EOF {
return l.Errorf("Unexpected end of subject")
}
if isSpace(r) {
l.Emit(styp)
return sfn
}
return l.Errorf("Invalid character %v found for itemType: %v", r, styp)
}
// lexArgInside is used to lex the arguments inside ().
func lexArgInside(l *lex.Lexer) lex.StateFn {
for {
switch r := l.Next(); {
case r == lex.EOF:
return l.Errorf("unclosed argument")
case isSpace(r) || isEndOfLine(r) || r == comma:
l.Ignore()
case isNameBegin(r):
return lexArgName
case r == ':':
l.Ignore()
return lexArgVal
case r == rightRound:
l.Emit(itemRightRound)
return lexInside
default:
return l.Errorf("argument list invalid")
}
}
}
// lexText lexes the input string and calls other lex functions.
func lexText(l *lex.Lexer) lex.StateFn {
Loop:
for {
switch r := l.Next(); {
case r == lex.EOF:
break Loop
case isNameBegin(r):
l.Backup()
return lexStart
case isSpace(r) || isEndOfLine(r):
l.Ignore()
default:
return l.Errorf("Invalid schema. Unexpected %s", l.Input[l.Start:l.Pos])
}
}
if l.Pos > l.Start {
l.Emit(itemText)
}
l.Emit(lex.ItemEOF)
return nil
}
func lexStart(l *lex.Lexer) lex.StateFn {
for {
r := l.Next()
if isNameSuffix(r) {
continue // absorb
}
l.Backup()
// l.Pos would be index of the end of operation type + 1.
word := l.Input[l.Start:l.Pos]
if word == "scalar" {
l.Emit(itemScalar)
return lexScalar
} else if word == "type" {
l.Emit(itemType)
return lexObject
} else {
return l.Errorf("Invalid schema")
}
}
}
func lexVarInside(l *lex.Lexer) lex.StateFn {
for {
switch r := l.Next(); {
case r == lex.EOF:
return l.Errorf("unclosed argument")
case isSpace(r) || isEndOfLine(r):
l.Ignore()
case isDollar(r):
return lexVarName
case r == ':':
l.Ignore()
return lexVarType
case r == equal:
l.Emit(itemEqual)
l.Ignore()
return lexVarDefault
case r == rightRound:
l.Emit(itemRightRound)
return lexText
case r == comma:
l.Emit(itemComma)
l.Ignore()
default:
return l.Errorf("variable list invalid")
}
}
}
// lexOperationType lexes a query or mutation operation type.
func lexOperationType(l *lex.Lexer) lex.StateFn {
for {
r := l.Next()
if isNameSuffix(r) {
continue // absorb
}
l.Backup()
// l.Pos would be index of the end of operation type + 1.
word := l.Input[l.Start:l.Pos]
if word == "mutation" {
l.Emit(itemOpType)
l.Mode = mutationMode
} else if word == "fragment" {
l.Emit(itemOpType)
l.Mode = fragmentMode
} else if word == "query" {
l.Emit(itemOpType)
l.Mode = queryMode
} else {
if l.Mode == 0 {
l.Errorf("Invalid operation type")
}
}
break
}
return lexText
}
func lexInside(l *lex.Lexer) lex.StateFn {
for {
switch r := l.Next(); {
case r == rightCurl:
l.Depth -= 1
l.Emit(itemRightCurl)
if l.Depth == 0 {
return lexText
}
case r == leftCurl:
l.Depth += 1
l.Emit(itemLeftCurl)
case r == lex.EOF:
return l.Errorf("unclosed action")
case isSpace(r) || isEndOfLine(r) || r == ',':
l.Ignore()
case isNameBegin(r):
return lexName
case r == '#':
l.Backup()
return lexComment
case r == '(':
l.Emit(itemLeftRound)
return lexArgInside
default:
return l.Errorf("Unrecognized character in lexInside: %#U", r)
}
}
}
func lexUidNode(l *lex.Lexer, styp lex.ItemType, sfn lex.StateFn) lex.StateFn {
l.AcceptUntil(isSpace)
r := l.Peek()
if r == lex.EOF {
return l.Errorf("Unexpected end of uid subject")
}
in := l.Input[l.Start:l.Pos]
if !strings.HasPrefix(in, "_uid_:") {
return l.Errorf("Expected _uid_: Found: %v", l.Input[l.Start:l.Pos])
}
if _, err := strconv.ParseUint(in[6:], 0, 64); err != nil {
return l.Errorf("Unable to convert '%v' to UID", in[6:])
}
if isSpace(r) {
l.Emit(styp)
return sfn
}
return l.Errorf("Invalid character %v found for UID node itemType: %v", r,
styp)
}
// lexFilterInside expects input like ( (equal(...) && f(...)) || g(...) ).
func lexFilterInside(l *lex.Lexer) lex.StateFn {
for {
r := l.Next()
switch {
case r == leftRound:
l.Emit(itemLeftRound)
l.FilterDepth++
case r == rightRound:
if l.FilterDepth == 0 {
return l.Errorf("Unexpected right round bracket")
}
l.FilterDepth--
l.Emit(itemRightRound)
if l.FilterDepth == 0 {
return lexInside // Filter directive is done.
}
case r == lex.EOF:
return l.Errorf("Unclosed directive")
case isSpace(r) || isEndOfLine(r):
l.Ignore()
case isNameBegin(r):
return lexFilterFuncName
case r == '&':
r2 := l.Next()
if r2 == '&' {
l.Emit(itemFilterAnd)
return lexFilterInside
}
return l.Errorf("Expected & but got %v", r2)
case r == '|':
r2 := l.Next()
if r2 == '|' {
l.Emit(itemFilterOr)
return lexFilterInside
}
return l.Errorf("Expected | but got %v", r2)
default:
return l.Errorf("Unrecognized character in lexInside: %#U", r)
}
}
}
// lexComment lexes a comment text.
func lexComment(l *lex.Lexer) lex.StateFn {
for {
r := l.Next()
if isEndOfLine(r) {
l.Emit(itemComment)
return lexInside
}
if r == lex.EOF {
break
}
}
if l.Pos > l.Start {
l.Emit(itemComment)
}
l.Emit(lex.ItemEOF)
return nil // Stop the run loop.
}
func lexObjectPair(l *lex.Lexer) lex.StateFn {
for {
r := l.Next()
if isNameSuffix(r) {
continue // absorb
}
l.Backup()
l.Emit(itemObjectName)
break
}
L:
for {
switch r := l.Next(); {
case isSpace(r) || isEndOfLine(r):
l.Ignore()
case r == ':':
l.Emit(itemCollon)
break
case isNameBegin(r):
l.Backup()
break L
default:
return l.Errorf("Invalid schema. Unexpected %s", l.Input[l.Start:l.Pos])
}
}
for {
r := l.Next()
if isNameSuffix(r) {
continue // absorb
}
l.Backup()
l.Emit(itemObjectType)
break
}
return lexObjectBlock
}