crustimoney.string-grammar — nl.functionalbytes/crustimoney 0.0.0-165-0x9388

Create a parser based on a string grammar. The grammar is translated into combinators.

create-parser clj

(create-parser text)

(create-parser text other-parsers)

Create a parser based on a string-based grammar definition. If the definition contains multiple rules, a map of parsers is returned. The following definition describes the string grammar syntax in itself:

space            <- [\s]*

non-terminal=    <- [a-zA-Z_-]+
literal          <- '\'' > (:literal #'(\\\'|[^\'])*') '\''
character-class= <- '[' > #'(\\]|[^]])*' ']' [?*+]?
regex=           <- '#' > literal
ref              <- (non-terminal !'=' space !'<-')
end-of-file=     <- '$'

group-name       <- ':' > (:group-name [a-zA-Z_-]+)
group=           <- '(' > group-name? space choice space ')'

expr             <- ref / group / literal / character-class / end-of-file / regex

quantified       <- (:quantified expr (:operand [?+*])) / expr
lookahead        <- (:lookahead (:operand [&!]) > quantified) / quantified

cut=             <- '>>' / '>'

chain            <- (:chain lookahead (space (cut / lookahead))+) / lookahead
choice           <- (:choice chain (space '/' space chain)+) / chain

rule=            <- (:rule-name non-terminal '='?) space '<-' >> space choice
root=            <- (:rules (space rule space)+) / (:no-rules space choice space) $

To capture nodes in the parse result, you need to use named groups. If you postfix a rule name with =, the expression is automatically captured using the rule's name (without the postfix). Please read up on this at crustimoney.combinators/grammar.

A map of existing parsers can be supplied, which can be used by the string grammar. For example:

(create-parser "root <- 'Hello ' email"
               {:email (regex "...")})

vector-tree clj

(vector-tree text)

Low-level function which translates the string grammar into an intermediary vector-based representation. See crustimoney.vector-grammar for more on this format. This can be useful for debugging.