Module round_trip 

Mutation-guarded grammar interchange round trips.

A plain round trip (import, emit, re-import, compare) cannot tell a correct importer/emitter pair from two that are wrong in mutually cancelling ways, and it cannot tell an emitter that re-emits a cached source from one that prints the grammar it was given. The guard therefore changes the grammar before export, requires the change in the exported text and in the re-imported grammar, and checks both the imported and the re-imported grammar against independent accept and reject samples that do not come from the pair under test. It mirrors js/src/grammar-round-trip.js.

Structs

GrammarRoundTrip

The importer/emitter pair under test and the independent samples.

GrammarRoundTripFailure

One failed check.

GrammarRoundTripReport

The outcome of check_grammar_round_trip.

Enums

GrammarRoundTripError

Why the guard could not run.

GrammarRoundTripFailureKind

What a failed check found.

GrammarRoundTripStage

The grammar a failed check looked at.

GrammarRoundTripStatus

Whether the pair carried the grammar and the mutation.

Constants

GRAMMAR_ROUND_TRIP_MARKER

The literal alternative the guard adds to the start rule by default.

Functions

accepts_text

Whether text parses with grammar on the native executor, as the JavaScript acceptsText does.

canonical_rule_definition

The meaning-aware definition of a rule.

check_grammar_round_trip

Round trips source through a mutated export and reports every failure.

mutate_grammar_start_rule

Adds marker as a literal alternative of the start rule.

Type Aliases

GrammarEmitFn

Emits a grammar in one notation, with its fidelity report.

GrammarImportFn

Imports grammar source text of one notation.