NAME

cru_stretcher - specification for intermediate vertex creation

SYNOPSIS

#include <cru/cru.h>

typedef struct cru_stretcher_s
{
   int st_fix;
   cru_tpred expander;
   struct cru_prop_s st_prop;
} *cru_stretcher;

DESCRIPTION

This structure parameterizes the cru_stretched library function with necessary information initialized by the application to expand a graph by interposing new vertices selectively along the edges between existing vertices.

• For each vertex in the graph, a property is computed according to the st_prop field by the usual cru_prop calling conventions.
• For each edge in the graph, the expander ternary predicate is passed the edge's label as its middle operand and the properties of the edge's origin and terminus as its left and right operands, respectively.
• For each call to the cru_stretch library function the predicate makes before returning, a new vertex is inserted between the origin and the terminus and connected to them by two new edges with labels given by the parameters passed to cru_stretch.
• If the predicate returns a non-zero value, the edge whose label it is passed is deleted.
• If the st_fix field is non-zero, then this process is iterated across the graph until the ternary predicate declines to create any new vertices or until the graph's designated vertex limit is reached.

The vertex reduction operator in the st_prop field is not needed and may be omitted or initialized to NULL.

ERRORS

These errors might be reported by the cru_stretched function for the reasons indicated.

CRU_UNDEXP

No function is defined in the expander field.

CRU_INTOVF

A vertex limit previously associated with the graph during its creation is reached or exceeded due to the creation of more vertices.

NOTES

The vertex limit in a graph is set according to the cru_sig structure used to build or modify it.

FILES

/usr/local/include/cru/data_types.h

/usr/local/include/cru/error_codes.h

SEE ALSO

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_singleton, cru_split, cru_splitter, cru_spread, cru_strerror, cru_stretch, cru_stretched, cru_subconnector, cru_terminus_count, cru_top, cru_tpred, cru_united, cru_uop, cru_vertex_count, cru_zone

AUTHOR

Dennis Furey (milonga@delayinsensitive.com)

PROJECT PAGE

https://github.com/gueststar/cru