roll-parser - v3.4.0
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    Function isNotationError

    • Type guard for the failures the input is answerable for: a roll-parser error whose code is one of NOTATION_ERROR_CODES. This is the test to hang a user-facing message on — isRollParserError only establishes origin, and answers true for a bad options object and a broken library invariant too, both of which should page you instead.

      Pair the two: the outer filter rethrows what is not ours, and this one splits what is left into "tell the user" and "report a bug".

      Unlike isRollParserError, this one has to read the code against the list this build carries — attribution is not something a brand can express. So where the outer filter accepts a code it has never heard of, this one rejects it: an error from a newer minor carrying a notation code added after this build reads as false and is misfiled as internal. That is the safe direction — it pages a developer rather than blaming a user — but keep the library and its consumers on one version when the distinction drives more than a message.

      Parameters

      • value: unknown

        The caught value, of unknown type

      Returns value is RollParserError & {
          code:
              | "UNEXPECTED_CHARACTER"
              | "UNEXPECTED_IDENTIFIER"
              | "UNEXPECTED_TOKEN"
              | "UNEXPECTED_END"
              | "EXPECTED_TOKEN"
              | "INVALID_DICE_COUNT"
              | "INVALID_DICE_SIDES"
              | "DICE_LIMIT_EXCEEDED"
              | "DIVISION_BY_ZERO"
              | "MODULO_BY_ZERO"
              | "INVALID_KEEP_DROP_COUNT"
              | "INVALID_KEEP_DROP_TARGET"
              | "EXPLODE_LIMIT_EXCEEDED"
              | "INVALID_EXPLODE_TARGET"
              | "REROLL_LIMIT_EXCEEDED"
              | "INVALID_REROLL_TARGET"
              | "INVALID_SUCCESS_COUNT_TARGET"
              | "INVALID_SORT_TARGET"
              | "INVALID_CRIT_THRESHOLD_TARGET"
              | "INVALID_DIE_BOUND_TARGET"
              | "INVALID_THRESHOLD"
              | "NESTED_VERSUS"
              | "INVALID_FUNCTION_ARITY"
              | "UNDEFINED_VARIABLE"
              | "AMBIGUOUS_DICE_CHAIN"
              | "MAX_DEPTH_EXCEEDED"
              | "NON_FINITE_RESULT"
              | "INVALID_NOTATION_TYPE";
      }

      true when value is a roll-parser error the input caused

      import { isNotationError, isRollParserError, roll } from 'roll-parser';

      try {
        roll(userInput);
      } catch (error) {
        if (!isRollParserError(error)) throw error;
        if (isNotationError(error)) reply(`Bad notation: ${error.message}`);
        else report(error); // our bug or yours — never the user's
      }

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