Grammar¶

Query grammar definition.

class cumin.grammar.Backend(keyword, name, cls)¶

Bases: tuple

collections.namedtuple() that define a Backend object.

Keyword Arguments:
	keyword (str) -- The backend keyword to be used in the grammar. name (str) -- The backend name. cls (BaseQuery) -- The backend class object.

cls¶: See the Keyword Arguments description.

keyword¶: See the Keyword Arguments description.

name¶: See the Keyword Arguments description.

cumin.grammar.get_registered_backends(external=())[source]¶

Get a mapping of all the registered backends with their keyword.

Parameters:	external (list, tuple, optional) -- external backend modules to register.
Returns:	A dictionary with a `{keyword: Backend object}` mapping for each available backend.
Return type:	dict
Raises:	`cumin.CuminError` -- If unable to register a backend.

cumin.grammar.grammar(backend_keys)[source]¶

Define the main multi-query grammar.

Cumin provides a user-friendly generic query language that allows to combine the results of subqueries for multiple backends:

Each query part can be composed with the others using boolean operators and, or, and not, xor.
Multiple query parts can be grouped together with parentheses (, ).
Specific backend query I{backend-specific query syntax}, where I is an identifier for the specific backend.
Alias replacement, according to aliases defined in the configuration file A:group1.
The identifier A is reserved for the aliases replacement and cannot be used to identify a backend.
A complex query example: (D{host1 or host2} and (P{R:Class = Role::MyClass} and not A:group1)) or D{host3}

Backus-Naur form (BNF) of the grammar:

      <grammar> ::= <item> | <item> <boolean> <grammar>
         <item> ::= <backend_query> | <alias> | "(" <grammar> ")"
<backend_query> ::= <backend> "{" <query> "}"
        <alias> ::= A:<alias_name>
      <boolean> ::= "and not" | "and" | "xor" | "or"

Given that the pyparsing library defines the grammar in a BNF-like style, for the details of the tokens not specified above check directly the source code.

Parameters:	backend_keys (list) -- list of the GRAMMAR_PREFIX for each registered backend.
Returns:	the grammar parser.
Return type:	pyparsing.ParserElement