eclipse-aascw / aas-core-codegen / 35062787678

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Index the TypeScript enumeration tables instead of hashing (#693)

A generated TypeScript enumeration is numeric and dense: ``_generate_enum``
emits ``FirstLiteral = 0`` and lets the rest auto-increment, and
``_generate_model_type_enum`` spells out ``Literal = i``. The comment in
``_generate_enum`` has always said what follows from that::

    // We optimize for comparisons instead of stringification.
    // The stringification is delegated to a separate module, with efficient
    // array look-ups to get the actual string value of a literal.

There were no array look-ups. Every literal-to-text table was a ``Map`` keyed
by the literal -- a hash over an integer that is already the index we want::

    const KEY_TYPES_TO_STRING = new Map<AasTypes.KeyTypes, string>([
      [AasTypes.KeyTypes.AnnotatedRelationshipElement, "AnnotatedRelationshipElement"],
      ...
    ]);

Now it is what it claimed to be::

    const DATA_TYPE_DEF_XSD_TO_STRING: readonly string[] = [
      "xs:anyURI", // AnyUri
      "xs:base64Binary", // Base64Binary
      ...
    ];

The literal is named in a trailing comment only where the text does not
already give it away, so ``MODEL_TYPE_TO_STRING`` and ``KEY_TYPES_TO_STRING``
stay bare while ``DATA_TYPE_DEF_XSD_TO_STRING`` stays checkable. That follows
``_generate_over_enum``, which already writes ``yield <Name>0; // Literal``.

Measured on the generated ``aas_core_meta.v3`` code, best of five runs:

    mustKeyTypesToString    8.1 ns/op -> 3.4 ns/op   (2.40x)
    mustModelTypeToString   7.5 ns/op -> 3.4 ns/op   (2.23x)

Nothing public moves. The tables were already module-private, and
``xToString`` / ``mustXToString`` keep their signatures, their ``null``
contract and the same ``Invalid literal of X: ${value}`` message. An
out-of-range cast such as ``<KeyTypes>99`` yields ``undefined`` from the
array exactly as it did from ``Map.get``.

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