datalog.parser.pull — org.clojars.timokramer/datalog-parser 0.1.27

IPullSpecComponent clj/s protocol

-as-spec clj/s

(-as-spec this)

parse-pattern clj/s

(parse-pattern pattern)

Parse an EDN pull pattern into a tree of records using the following grammar:

pattern            = [attr-spec+]
attr-spec          = attr-name | wildcard | map-spec | attr-expr
attr-name          = an edn keyword that names an attr
wildcard           = "*" or '*'
map-spec           = { ((attr-name | limit-expr) (pattern | recursion-limit))+ }
attr-with-opts     = [attr-name attr-options+]
attr-options       = :as any-value | :limit (positive-number | nil) | :default any-value
attr-expr          = limit-expr | default-expr
limit-expr         = ["limit" attr-name (positive-number | nil)]
default-expr       = ["default" attr-name any-value]
recursion-limit    = positive-number | '...'

parse-pull clj/s

(parse-pull pattern)

Parse EDN pull pattern specification (see parse-pattern), and convert the resulting tree into a PullSpec instance (see pattern->spec). Throws an error if the supplied pattern cannot be parsed.

pattern->spec clj/s

(pattern->spec pattern)

Convert a parsed tree of pull pattern records into a PullSpec instance, a record type containing two keys:

• :wildcard? - a boolean indicating if the pattern contains a wildcard.
• :attrs - a map of attribute specifications.

The attribute specification map consists of keys which will become the keys in the result map, and values which are themselves maps describing the attribute:

• :attr (required) - The attr name to pull; for reverse attributes this will be the normalized attribute name.
• :as (optional) - Alias, any
• :limit (optional) - If present, specifies a custom limit for this attribute; Either nil, indicating no limit, or a positive integer.
• :default (optional) - If present, specifies a default value for this attribute
• :recursion (optional) - If present, specifies a recursion limit for this attribute; Either nil, indicating no limit, or a positive integer.
• :subpattern (optional) - If present, specifies a sub PullSpec instance to be applied to entities matched by this attribute.