Add a grammar health checker for two HermitCrab admissibility preconditions - #475
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Add a grammar health checker for two HermitCrab admissibility preconditions#475johnml1135 wants to merge 1 commit into
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…itions HermitCrab imposes two requirements on a grammar that nothing reports today, so a grammar author only learns of a violation as a parse that silently returns nothing. Every segment used must be declared in a CharacterDefinitionTable: an undeclared segment makes the parser refuse every word containing it. And each segment needs a distinct phonological feature bundle within its table: when two share one, the parser cannot reliably determine which morphemes are involved. GrammarHealthChecker.Check(Language) reports both as findings with a severity, a stable code and the offending declarations named. It is diagnostic only -- a grammar the engine would load still loads, and nothing throws. Lives in the netstandard2.0 engine library rather than a tool, so FieldWorks and any other host can call it directly on a loaded Language. The duplicate-bundle check is skipped for a grammar that declares no PhonologicalFeatureSystem at all. Such a grammar distinguishes segments by their representation alone, so every bundle is the same empty struct by construction and reporting it would be a false positive on a correct grammar.
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HermitCrab imposes two requirements on a grammar that nothing currently reports. A grammar author only discovers a violation as a parse that silently returns nothing, which is a hard failure to diagnose from the outside.
Every segment used must be declared in a
CharacterDefinitionTable. An undeclared segment makes the parser refuse every word containing it — total, and silent-looking.Each segment needs a distinct phonological feature bundle within its table. When two segments share one, the parser cannot reliably determine which morphemes are involved.
GrammarHealthChecker.Check(Language)reports both as findings carrying a severity, a stable code, and the offending declarations named so a host can navigate to them.Design notes
Diagnostic only. It never throws and never changes parse behaviour — a grammar the engine would load still loads. It reports; the host decides what to do.
In the
netstandard2.0engine library, not a tool. So it ships in theSIL.Machine.Morphology.HermitCrabNuGet package and any host — FieldWorks, or anyone testing their own grammar — can call it directly on a loadedLanguage. Verified by packing:lib/netstandard2.0/SIL.Machine.Morphology.HermitCrab.dll.The duplicate-bundle check is skipped when a grammar declares no
PhonologicalFeatureSystemat all. Such a grammar distinguishes segments by their representation alone, so every bundle is the same empty struct by construction. Reporting that would be a false positive on a correct grammar, and grammars of exactly this shape exist.Tests
Five tests covering both checks, the clean case, and the feature-less-grammar case. They build the object model directly rather than loading XML, so they have no external fixture dependency. Full HermitCrab suite passes (73/73).
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