RQL Grammar Specification¶

This document contains the formal grammar and structural definitions used by the Rule Query Language (RQL). It is primarily intended for implementers and advanced users that need a precise description of the language syntax.

Technical Specification¶

Statements¶

An RQL script consists of one or more statements, each terminated by a semicolon (;).

<statement> ::= <expression_statement> ;

Expression Statement¶

An expression statement is an expression followed by a semicolon.

<expression_statement> ::= <expression> ;

Expressions¶

Expressions are the building blocks of RQL and can be of several types.

<expression> ::=
    <match_expression>
    | <search_expression>
    | <assignment_expression>
    | <new_object_expression>
    | <new_array_expression>
    | <binary_expression>
    | <unary_expression>
    | <literal_expression>
    | <identifier_expression>
    | <placeholder_expression>

Literal Expressions¶

Literal values represent fixed data in the language. Supported literals include:

• String – quoted with double quotes ("text").
• Integer – whole numbers (123).
• Decimal – floating‑point numbers (1.23).
• Boolean – TRUE or FALSE.
• Date/Time – enclosed in dollar signs ($2024-01-01T12:00:00Z$).
• NOTHING – the absence of a value.

The grammar for a literal is:

<literal_expression> ::=
    <string_literal>
    | <integer_literal>
    | <decimal_literal>
    | <boolean_literal>
    | <date_literal>
    | NOTHING

MATCH Expression¶

The MATCH expression is used to retrieve rules.

Syntax

MATCH ( ONE RULE | ALL RULES )
FOR <ruleset_name>
ON <date>
[ WHEN { <conditions> } ]

Note: the ON <date> clause is required and specifies the evaluation date.

Arguments

• ONE RULE | ALL RULES (required) Specifies the cardinality of the match.

• FOR <ruleset_name> (required) Specifies the ruleset to match rules from. <ruleset_name> is a string literal.

• ON <date> (required) Specifies the evaluation date. <date> is a date/time literal.

• WHEN { <conditions> } (optional) A set of conditions to filter the rules. See Conditions for more details.

SEARCH Expression¶

The SEARCH expression is used to search for rules.

Syntax

SEARCH RULES
FOR <ruleset_name>
SINCE <date>
UNTIL <date>
[ WHEN { <conditions> } ]

Note: both SINCE and UNTIL clauses are required to define the evaluation range.

Arguments

• FOR <ruleset_name> (required) Specifies the ruleset to search in. <ruleset_name> is a string literal.

• SINCE <date> (required) The start of the date range for the search.

• UNTIL <date> (required) The end of the date range for the search.

• WHEN { <conditions> } (optional) A set of conditions to filter the rules. See Conditions for more details.

OBJECT Expression¶

The OBJECT expression is used to create a new object.

Syntax

OBJECT [ { <property_assignments> } ]

Arguments

• <property_assignments> (optional) A comma-separated list of property assignments. Each assignment has the following syntax: <property_name> = <value>
  • <property_name>: A string literal.
  • <value>: Any valid expression.

ARRAY Expression¶

The ARRAY expression is used to create a new array.

Syntax

ARRAY [ <size> ] | ARRAY { <elements> }

Arguments

• [ <size> ] Creates an array of a specific size, initialized with NOTHING values. <size> is an integer literal.

• { <elements> } Creates an array with a list of initial elements. <elements> is a comma-separated list of expressions.

Conditions¶

Conditions are used in the WHEN clause of a MATCH expression and a SEARCH expression.

Syntax

<condition> [, <condition>...]

Each condition has the following syntax:

@<condition_name> IS <value>

• @<condition_name> The name of the condition, prefixed with @.

• <value> A literal value or an expression.