Module sample_selector 

DDS-WEB Sample Selector BNF Parser — Spec §7.4.8.

Implements §7.4.8 fully.

Spec source: OMG DDS-WEB 1.0 §7.4.8 (pp. 51-53) — DataReader::read with the SampleSelector BNF grammar:

SampleSelector  ::= FilterExpression ( ',' MetadataExpression )?
FilterExpression ::= Term ( ('AND' | 'OR') Term )*
Term            ::= Atom | '(' FilterExpression ')'
Atom            ::= FieldRef CompOp Literal
MetadataExpression ::= 'sample_state=' SampleState
                     | 'view_state='   ViewState
                     | 'instance_state='InstanceState

The parser returns an AST SampleSelector that the caller can translate into a DDS [QueryCondition] (crates/dcps/src/query_condition.rs).

Structs

SampleSelector

Top-level AST of the sample-selector expression.

Enums

BoolOp

Boolean operator.

CompareOp

Comparison operator (Spec §7.4.8).

FilterExpression

Filter expression — boolean expression over field references.

InstanceStateMatch

Spec §7.4.8 — instance-state match.

Literal

Literal value on the right-hand side of a comparison.

MetadataExpression

Metadata expression from Spec §7.4.8.

ParseError

Parser error.

SampleStateMatch

Spec §7.4.8 — sample-state match (DDS DCPS §2.2.2.5).

ViewStateMatch

Spec §7.4.8 — view-state match.

Functions

parse_sample_selector

Parses a sample-selector string per Spec §7.4.8 BNF.