Function method_implies_lambda_args

internal/cbm/lsp/java_lsp.c:2298–2345

Heuristic table mapping (receiver kind, method name) → lambda arg shape. * * Used when the registry's CBMRegisteredFunc lacks param-type metadata * (most stdlib registrations are return-only) but the receiver's template * args make the SAM-arg type unambiguous. * * Returns true and fills out_arity + out_param[0..1] when a heuristic * matches. The lambda binder then uses these directly witho

 * matches. The lambda binder then uses these directly without going
 * through the SAM-spec table. */
static bool method_implies_lambda_args(const char *recv_qn, const char *method_name,
                                       const CBMType *const *targs, int targ_count, int *out_arity,
                                       const CBMType **out_param0, const CBMType **out_param1) {
    *out_arity = 0;
    *out_param0 = NULL;
    *out_param1 = NULL;
    if (!recv_qn || !method_name || !targs || targ_count <= 0)
        return false;

    /* 1-param lambdas over T0 — Predicate / Consumer / Function shapes. */
    static const char *one_arg_methods[] = {
        "forEach",         "filter",   "map",       "flatMap",     "peek",      "removeIf",
        "anyMatch",        "allMatch", "noneMatch", "takeWhile",   "dropWhile", "ifPresent",
        "ifPresentOrElse", "mapToInt", "mapToLong", "mapToDouble", "filter",    NULL,
    };
    for (int i = 0; one_arg_methods[i]; i++) {
        if (strcmp(method_name, one_arg_methods[i]) == 0) {
            *out_arity = 1;
            *out_param0 = targs[0];
            return true;
        }
    }
    /* Map<K,V>.forEach takes BiConsumer<K, V> (2 params). */
    if (is_map_like(recv_qn) && targ_count >= 2) {
        if (strcmp(method_name, "forEach") == 0 || strcmp(method_name, "replaceAll") == 0 ||
            strcmp(method_name, "compute") == 0 || strcmp(method_name, "computeIfPresent") == 0 ||
            strcmp(method_name, "merge") == 0) {
            *out_arity = 2;
            *out_param0 = targs[0];
            *out_param1 = targs[1];
            return true;
        }
        if (strcmp(method_name, "computeIfAbsent") == 0) {
            /* Function<K, V> — 1-arg of K. */
            *out_arity = 1;
            *out_param0 = targs[0];
            return true;
        }
    }
    /* Comparator-typed args — keep simple: Comparator<T0>.compare(T0, T0). */
    if (strcmp(method_name, "sort") == 0 && targ_count >= 1) {
        *out_arity = 2;
        *out_param0 = targs[0];
        *out_param1 = targs[0];
        return true;
    }
    return false;
}

/* When a method on a TEMPLATE receiver returns a NAMED type that is itself
 * a parametric "carrier" (Stream, Iterator, Optional, …), preserve the