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#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include "graph.h"
// Hashtable
static unsigned int hash(char *s)
{
uint32_t hv = 0;
for( int i = 0; s[i] != '\0'; i++ ) {
// take MSB 6 bits of hv and xors with LSB of s[i]
uint32_t v = ( hv >> 26 ) ^ (s[i] & 0x3f);
// Push those back on hv
hv = (hv << 4) | v;
}
// Return appropriate size
return hv % HASHSIZE;
}
static void table_insert(graph_t *g, vertex_t *v, char *var)
{
unsigned int index = hash(var);
// Save old value
vertex_t *oldSym = g->hashtable[index];
// Make new
g->hashtable[index] = v;
// Link old one
g->hashtable[index]->next = oldSym;
}
static vertex_t *table_lookup(graph_t *g, char *var)
{
unsigned int index = hash(var);
vertex_t *n = g->hashtable[index];
// Look trough list
while (n != NULL && strcmp(n->ref, var) != 0) {
n = n->next;
}
return n;
}
static vertex_t *create_vertex(char *ref)
{
// Get some space TODO check for null
vertex_t *v = malloc(sizeof(vertex_t));
// Set values
v->ref = strdup(ref);
v->color = COLOR_WHITE;
v->next = NULL;
v->adj = NULL;
return v;
}
static edge_t *create_edge(vertex_t *from, vertex_t *to, int weight)
{
edge_t *old = from->adj;
// Create new list node
edge_t *e = malloc(sizeof(edge_t));
e->weight = weight;
e->from = from;
e->to = to;
// Do new link
e->next = old;
if ( old ) {
e->prev = old->prev;
old->prev = e;
} else {
e->prev = NULL;
}
if ( e->prev ) {
e->prev->next = e;
}
from->adj = e;
return e;
}
// For iterating edges
edge_t *edge_next(graph_t *g, edge_t *e)
{
if (e == NULL || e->next == NULL ) {
// Find next index
vertex_t *v = e ? e->from : NULL;
// Find next vertex
v = vertex_next(g, v);
while ( v ) {
// Check if found
if ( v->adj ) {
return v->adj;
}
v = vertex_next(g, v);
}
// No next vertex
return NULL;
}
// Not finished with this adj list
return e->next;
}
vertex_t *vertex_next(graph_t *g, vertex_t *v)
{
if ( v == NULL || v->next == NULL) {
// Go to next index in hashtable
int i = v ? hash(v->ref)+1 : 0;
for ( ; i < HASHSIZE; i++) {
if ( g->hashtable[i] ) {
return g->hashtable[i];
}
}
// No next
return NULL;
}
return v->next;
}
void graph_edge(graph_t *g, char *from, char *to, int weight)
{
vertex_t *fromv, *tov;
// Does a exists
if ( (fromv = table_lookup(g, from)) == NULL ) {
fromv = create_vertex(from);
table_insert(g, fromv, from);
}
// What about b
if ( (tov = table_lookup(g, to)) == NULL ) {
tov = create_vertex(to);
table_insert(g, tov, to);
}
// Add edge
create_edge(fromv, tov, weight);
}
int graph_print_adj(graph_t *g, char *ref)
{
vertex_t *v = table_lookup(g, ref);
if ( v == NULL ) {
return 1;
}
edge_t *e = v->adj;
printf("[ ");
while (e && e->from->ref == ref) {
printf("%s[%d] ", e->to->ref, e->weight);
e = e->next;
}
printf("]\n");
return 0;
}
int graph_to_dot(FILE *f, graph_t *g)
{
// print pre stuff
fprintf(f, "digraph coolgraph {\n");
// Label all nodes
vertex_t *v = vertex_next(g, NULL);
while ( v ) {
fprintf(f, "%s [label=\"%s\"];\n", v->ref, v->ref);
v = vertex_next(g, v);
}
// Print all the edges
edge_t *e = edge_next(g, NULL);
while ( e ) {
fprintf(f, "%s -> %s [label = %d];\n", e->from->ref, e->to->ref, e->weight);
e = edge_next(g, e);
}
// done
fprintf(f, "}\n");
}
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