This is a [x]QL generic lexer parser, that should be useful for constructing Dialect Specific Lexer/Parsers.
[x]QL languages are making a comeback. It is still an easy, approachable way of interrogating data. Also, we see more and more ql's that are xql'ish but un-apologetically non-standard. This matches our observation that data is stored in more and more formats in more tools, services that aren't traditional db's but querying that data should still be easy. Examples Influx, GitQL, Presto, Hive, CQL, yql, ql.io, etc
- Base Lex tools for parsing ql type languages, native GO lexer
- Common Dialects
- base script interpreter for execution of ql functions (ie, query csv data)
See example in exampledialect folder for a custom ql dialect, this
example creates a mythical SUBSCRIBETO query language...
// Tokens Specific to our PUBSUB
var TokenSubscribeTo ql.TokenType = 1000
// Custom lexer for our maybe hash function
func LexMaybe(l *ql.Lexer) ql.StateFn {
l.SkipWhiteSpaces()
keyWord := strings.ToLower(l.PeekWord())
switch keyWord {
case "maybe":
l.ConsumeWord("maybe")
l.Emit(ql.TokenIdentity)
return ql.LexExpressionOrIdentity
}
return ql.LexExpressionOrIdentity
}
func main() {
// We are going to inject new tokens into QLparser
ql.TokenNameMap[TokenSubscribeTo] = &ql.TokenInfo{Description: "subscribeto"}
// OverRide the Identity Characters in QLparser to allow a dash in identity
ql.IDENTITY_CHARS = "_./-"
ql.LoadTokenInfo()
ourDialect.Init()
// We are going to create our own Dialect that uses a "SUBSCRIBETO" keyword
pubsub = &ql.Statement{TokenSubscribeTo, []*ql.Clause{
{Token: TokenSubscribeTo, Lexer: ql.LexColumns},
{Token: ql.TokenFrom, Lexer: LexMaybe},
{Token: ql.TokenWhere, Lexer: ql.LexColumns, Optional: true},
}}
ourDialect = &ql.Dialect{
"Subscribe To", []*ql.Statement{pubsub},
}
l := ql.NewLexer(`
SUBSCRIBETO
count(x), Name
FROM ourstream
WHERE
k = REPLACE(LOWER(Name),'cde','xxx');
`, ourDialect)
}