Elm simple elastic query

Parse and serialize ElasticSearch search query strings.

This package allows to parse an elastic simple query string into an AST, and serialize string search queries out of it.

Notes:

• Serialization will enforce classic boolean operator precedence by using parenthesis groups everywhere applicable.

Demo

Alphabet

( ) Group
[WORD] Char+
| OR
\+ AND
-- Exclude
"" Exact
~n Fuzzy
\* Prefix

Specific case : Spaces (signifying in some contexts and not in others)

AST

type Expr
    = And (List Expr)
    | Exact String
    | Exclude Expr
    | Fuzzy Int String
    | Or (List Expr)
    | Prefix String
    | Word String

Production rules

Unless explicitly indicated, spaces are ignored.

Query => ORExpr EOF
ORExpr => ANDExpr | ANDExpr "|" ORExpr
ANDExpr => EXCExpr | EXCExpr ("+"|\s+) ANDExpr
EXCExpr => "-" GRPExpr | GRPExpr
GRPExpr => WORD~"\*" | WORD~"\~2" | WORD | \" EXACTExpr \" | "(" ORExpr ")"
EXACTExpr => [^"]+

Example

Source query string:

big* (potatoes | "french fries") -salad

Parsing:

$ elm repl
---- Elm 0.19.0 ----------------------------------------------------------------
Read <https://elm-lang.org/0.19.0/repl> to learn more: exit, help, imports, etc.
--------------------------------------------------------------------------------
> import Elastic exposing (Expr(..))   
> Elastic.parse "big* (potatoes | \"french fries\") -salad"
Ok (And [Prefix "big",Or [Word "potatoes",Exact ("french fries")],Exclude (Word "salad")])
  : Result (List Parser.DeadEnd) Elastic.Expr

Serialization:

> Elastic.serialize (And [Prefix "big",Or [Word "potatoes",Exact ("french fries")],Exclude (Word "salad")])
"big* (potatoes | \"french fries\") -salad" : String

License

MIT