func LexForExpr(l *lex.Lexer) lex.StateFn {
if int(l.Pos) >= len(l.Input) {
l.Emit(lex.ItemEOF)
return nil
}
if strings.HasPrefix(l.Input[l.Pos:], "in") {
l.Pos += lex.Pos(2)
l.Emit(ItemIn)
return InsideAction
}
// any list of space separated identifiers
switch r := l.Next(); {
case lex.IsSpace(r):
for lex.IsSpace(l.Peek()) {
l.Next()
}
l.Emit(ItemSpace)
return LexForExpr
case unicode.IsLetter(r):
return LoopIdentifier
default:
return l.Errorf("Unexpected Character '%s'", string(r))
}
}
func Space(l *lex.Lexer) lex.StateFn {
for lex.IsSpace(l.Peek()) {
l.Next()
}
l.Emit(ItemSpace)
return InsideAction
}
func InsideAction(l *lex.Lexer) lex.StateFn {
if l.Name == "LexTextNode" && strings.HasPrefix(l.Input[l.Pos:], rightDelim) {
if l.IntState[ActionParenDepth] > 0 {
return l.Errorf("unmatched parentheses")
}
return RightDelim
}
switch r := l.Next(); {
case (r == lex.EOF || lex.IsEndOfLine(r)):
if l.Name == "LexIfExpr" {
return LexIfExpr
}
if l.Name == "LexForExpr" {
return LexForExpr
}
// if reach eof throw while still in action throw error
return l.Errorf("unclosed action")
case lex.IsSpace(r):
return Space
case unicode.IsLetter(r): //variable and function must begin with a letter
return Identifier
case r == '!':
if unicode.IsLetter(l.Peek()) {
return Identifier
}
return l.Errorf("invalid character in builtin")
case r == '#' || r == '+':
if unicode.IsLetter(l.Peek()) {
return EspraURI
}
return l.Errorf("invalid character in URI")
case r == '-' || unicode.IsDigit(r):
l.Backup()
return Number
case r == '\'' || r == '"':
l.Emit(ItemOpenQuote)
return String
case r == '(':
l.IntState[ActionParenDepth] += 1
l.Emit(ItemLeftParen)
case r == ')':
l.IntState[ActionParenDepth] -= 1
l.Emit(ItemRightParen)
case r == '|':
l.Emit(ItemPipe)
default:
return l.Errorf("Unexpected Character '%s'", string(r))
}
return InsideAction
}
func LexTextNode(l *lex.Lexer) lex.StateFn {
for {
r := l.Next()
if lex.IsAlphaNumeric(l.Peek()) {
if lex.IsSpace(r) || lex.IsEndOfLine(r) {
l.Emit(ItemText)
}
i := lex.Pos(strings.IndexAny(l.Input[l.Pos:], " \t\n\r"))
if i != -1 {
i = l.Pos + i
} else {
i = lex.Pos(len(l.Input) - 1)
}
if strings.Contains(l.Input[l.Pos:i], ":") {
l.Pos = i
return LexURI
}
}
l.Backup()
if strings.HasPrefix(l.Input[l.Pos:], leftDelim) {
if l.Pos > l.Start {
l.Emit(ItemText)
}
return LeftDelim
}
if l.Next() == lex.EOF {
break
}
}
// Correctly reached EOF.
if l.Pos > l.Start {
l.Emit(ItemText)
}
l.Emit(lex.ItemEOF)
return nil
}