cru_singleton - detect a graph of exactly one vertex
#include <cru/cru.h>
int cru_singleton ( cru_graph g , int *err )
This function detects whether the graph g has exactly one vertex. For memory management purposes, the graph is not consumed or modified.
On successful completion, this function returns zero if the graph g has no vertices or more than one vertex. If g has exactly one vertex, a non-zero value is returned.
The err parameter is used to report any events preventing successful completion of the requested operation to the caller. If *err is zero on entry and the operation does not succeed, then *err is assigned a non-zero number. Positive numbers are for POSIX or user-defined error codes, and negative numbers down to -CRU_MAX_ERR are specific to cru.
Values of *err listed below refer to errors that are detected and handled. Unlisted values in the range of -CRU_INT_ERR through -CRU_MAX_ERR likely indicate internal errors attributable to bugs in cru. Any other unlisted values may indicate memory corruption or invalid usage of the API.
CRU_BADGPH
The parameter g refers to an invalid or corrupted graph.
For a graph g, and integers s, t, and err, this code fragment demonstrates equivalent ways of detecting singleton graphs.
s = cru_singleton (g, &err);
t = (cru_vertex_count (g, CONCURRENTLY, &err) == 1);
if ((! s) == ! t)
printf ("results are as expected\n");
else
printf ("an error occurred\n");The cru_singleton function is faster and more efficient for this purpose than counting the vertices.
/usr/local/include/cru/cru.h
/usr/local/include/cru/data_types.h
/usr/local/include/cru/error_codes.h
cru, cru_bop, cru_bpred, cru_builder, cru_built, cru_cbop, cru_classifier, cru_class_of, cru_class_size, cru_composed, cru_composer, cru_connect, cru_connector, cru_cqop, cru_crossed, cru_crosser, cru_ctop, cru_ctop_pair, cru_ctop_quad, cru_data_types, cru_deduplicated, cru_destructor, cru_destructor_pair, cru_edge_count, cru_fabricated, cru_fabricator, cru_filter, cru_filtered, cru_fold, cru_free_kill_switch, cru_free_later, cru_free_now, cru_free_partition, cru_function_types, cru_get, cru_hash, cru_induced, cru_inducer, cru_kernel, cru_kill, cru_killed, cru_mapreduced, cru_mapreducer, cru_merged, cru_merger, cru_mutated, cru_mutator, cru_new_kill_switch, cru_nop, cru_order, cru_order_pair, cru_partition_of, cru_plan, cru_postponed, cru_postponer, cru_prop, cru_prop_pair, cru_pruner, cru_qop, cru_qpred, cru_set, cru_sig, cru_split, cru_splitter, cru_spread, cru_strerror, cru_stretch, cru_stretched, cru_stretcher, cru_subconnector, cru_terminus_count, cru_top, cru_tpred, cru_united, cru_uop, cru_vertex_count, cru_zone
Dennis Furey (milonga@delayinsensitive.com)
https://github.com/gueststar/cru