func lexPredicate(l *lex.Lexer) lex.StateFn {
r := l.Next()
if r != '<' {
return l.Errorf("Invalid character in lexPredicate: %v", r)
}
l.Depth += 1
return lexUntilClosing(l, itemPredicate, lexText)
}
func lexArgumentVal(l *lex.Lexer) lex.StateFn {
for {
switch r := l.Next(); {
case isSpace(r):
l.Ignore()
}
}
}
func lexPredicate(l *lex.Lexer) lex.StateFn {
r := l.Next()
// The predicate can only be an IRI according to the spec.
if r != '<' {
return l.Errorf("Invalid character in lexPredicate: %v", r)
}
l.Depth++
return lexUntilClosing(l, itemPredicate, lexText)
}
func lexObject(l *lex.Lexer) lex.StateFn {
r := l.Next()
// The object can be an IRI, blank node or a literal.
if r == '<' {
l.Depth++
return lexUntilClosing(l, itemObject, lexText)
}
if r == '_' {
l.Depth++
r = l.Next()
// TODO - Remove this, doesn't conform to the spec.
if r == 'u' {
return lexUidNode(l, itemObject, lexText)
}
if r == ':' {
return lexBlankNode(l, itemObject, lexText)
}
}
if r == '"' {
l.Ignore()
return lexLiteral(l)
}
return l.Errorf("Invalid char: %v at lexObject", r)
}
// 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 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 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 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])
}
}
}
// This function is used to absorb the object value.
func lexMutationValue(l *lex.Lexer) lex.StateFn {
for {
r := l.Next()
if r == '\\' {
// So that we don't count \" as end of value.
if l.Next() == quote {
continue
}
}
// This is an end of value so lets return.
if r == quote {
break
}
// We absorb everything else.
continue
}
return lexTextMutation
}
// 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)
}
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 == "mutation" {
l.Emit(itemOpType)
l.Mode = mutationMode
} else if word == "query" {
l.Emit(itemOpType)
l.Mode = queryMode
}
break
}
return lexText
}
func lexLabel(l *lex.Lexer) lex.StateFn {
r := l.Next()
// Graph label can either be an IRI or a blank node according to spec.
if r == '<' {
l.Depth++
return lexUntilClosing(l, itemLabel, lexText)
}
if r == '_' {
l.Depth++
r = l.Next()
if r != ':' {
return l.Errorf("Invalid char: %c at lexLabel", r)
}
l.Backup()
return lexBlankNode(l, itemLabel, lexText)
}
return l.Errorf("Invalid char: %v at lexLabel", r)
}
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 lexObject(l *lex.Lexer) lex.StateFn {
r := l.Next()
if r == '<' {
l.Depth += 1
return lexUntilClosing(l, itemObject, lexText)
}
if r == '_' {
l.Depth += 1
return lexBlankNode(l, itemObject, lexText)
}
if r == '"' {
l.Ignore()
return lexLiteral(l)
}
return l.Errorf("Invalid char: %v at lexObject", 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 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
}
func lexLabel(l *lex.Lexer) lex.StateFn {
r := l.Next()
if r == '<' {
l.Depth += 1
return lexUntilClosing(l, itemLabel, lexText)
}
if r == '_' {
l.Depth += 1
return lexBlankNode(l, itemLabel, lexText)
}
return l.Errorf("Invalid char: %v at lexLabel", 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 lexSubject(l *lex.Lexer) lex.StateFn {
r := l.Next()
if r == '<' {
l.Depth += 1
return lexUntilClosing(l, itemSubject, lexText)
}
if r == '_' {
l.Depth += 1
return lexBlankNode(l, itemSubject, lexText)
}
return l.Errorf("Invalid character during lexSubject: %v", r)
}
func lexSubject(l *lex.Lexer) lex.StateFn {
r := l.Next()
// The subject is an IRI, so we lex till we encounter '>'.
if r == '<' {
l.Depth++
return lexUntilClosing(l, itemSubject, lexText)
}
// The subject represents a blank node.
if r == '_' {
l.Depth++
r = l.Next()
// TODO - Remove this, doesn't conform to the spec.
if r == 'u' {
return lexUidNode(l, itemSubject, lexText)
}
if r == ':' {
return lexBlankNode(l, itemSubject, lexText)
}
}
// else go to error
return l.Errorf("Invalid character during lexSubject: %v", r)
}
// 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 == 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++ // one level down.
l.Emit(itemLeftCurl)
if l.Mode == mutationMode {
return lexInsideMutation
}
// Both queryMode and fragmentMode are handled by lexInside.
return lexInside
case r == rightCurl:
return l.Errorf("Too many right characters")
case r == lex.EOF:
break Loop
case r == leftRound:
l.Backup()
l.Emit(itemText)
l.Next()
l.Emit(itemLeftRound)
return lexVarInside
case isNameBegin(r):
l.Backup()
l.Emit(itemText)
return lexOperationType
}
}
if l.Pos > l.Start {
l.Emit(itemText)
}
l.Emit(lex.ItemEOF)
return nil
}
// 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])
}
}
}
// 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")
}
}
}
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
}
// 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
}
// 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)
}
}
}
