AdaptableCustomExpressionFunction

A 3rd-party custom expression function: one flat object combining the aql evaluation properties (handler, returnType, operands, docs, …) with the Adaptable-specific enhancement properties (icon, label, isAvailable, rhs, …).

The handler is typed against the public so evaluator internals are not part of the authoring contract.

Registered via expressionOptions.customStandardFunctions (boolean predicates are custom standard functions with returnType: 'boolean').

returnType is mandatory so AdapTable can distinguish predicates from value-producing functions — prefer / EXPRESSION_RETURN_TYPES. string & {} keeps literal autocomplete while remaining assignable when TypeScript widens 'boolean' to string (common for object literals in a Record | callback union).

Boolean predicates with operands of arity 1 or 2 appear in Query Builder / ColumnFilter (optional for the operator picker). Arity 0 / 3+ or non-boolean stay Expression-Editor-only.

isAvailable is narrowed to (not Layout / Cell Summary — those are aggregation-only).

export type AdaptableCustomExpressionFunction = Omit<AqlExpressionFunction<AdaptableExpressionContext> & AdaptableExpressionFunctionEnhancement, 'isAvailable' | 'returnType'> & {
    returnType: ExpressionReturnType | (string & {});
    isAvailable?: AdaptableStandardExpressionModule[] | ((context: ExpressionFunctionAvailabilityContext) => boolean);
};

References

AdaptableStandardExpressionModule | ExpressionFunctionAvailabilityContext