strans/trie.c

131 lines
2.1 KiB
C

#include "dat.h"
#include "fn.h"
static int
newnode(Trie *t)
{
int i;
if(t->n >= t->cap){
t->cap *= 2;
t->nodes = erealloc(t->nodes, t->cap * sizeof(Tnode));
}
i = t->n++;
memset(&t->nodes[i], 0, sizeof(Tnode));
t->nodes[i].child = -1;
t->nodes[i].sibling = -1;
return i;
}
static int
find(Trie *t, int ni, char c)
{
int pi;
for(pi = t->nodes[ni].child; pi >= 0; pi = t->nodes[pi].sibling)
if(t->nodes[pi].c == c)
return pi;
return -1;
}
static int
add(Trie *t, int ni, char c)
{
int pi;
pi = newnode(t);
t->nodes[pi].c = c;
t->nodes[pi].sibling = t->nodes[ni].child;
t->nodes[ni].child = pi;
return pi;
}
static void
insert(Trie *t, char *key, int klen, char *val, int vlen)
{
int ni, ci;
int i;
ni = t->root;
for(i = 0; i < klen; i++){
ci = find(t, ni, key[i]);
if(ci < 0)
ci = add(t, ni, key[i]);
ni = ci;
}
t->nodes[ni].val = val;
t->nodes[ni].vlen = vlen;
}
Trie*
trieopen(char *path)
{
Trie *t;
Biobuf *b;
char *line, *tab, *key, *val;
int klen, vlen;
b = Bopen(path, OREAD);
if(b == nil)
die("can't open: %s", path);
t = emalloc(sizeof(*t));
t->cap = 1024;
t->nodes = emalloc(t->cap * sizeof(Tnode));
t->n = 0;
t->root = newnode(t);
while((line = Brdstr(b, '\n', 1)) != nil){
if(line[0] == '\0'){
free(line);
continue;
}
tab = strchr(line, '\t');
if(tab == nil || tab[1] == '\0')
die("malformed map: %s", path);
*tab = '\0';
key = line;
klen = tab - line;
val = tab + 1;
vlen = strlen(val);
insert(t, key, klen, val, vlen);
}
Bterm(b);
return t;
}
char*
trieget(Trie *t, char *key, int klen, int *vlen)
{
int ni;
int i;
ni = t->root;
for(i = 0; i < klen; i++){
ni = find(t, ni, key[i]);
if(ni < 0)
return nil;
}
if(t->nodes[ni].val == nil)
return nil;
*vlen = t->nodes[ni].vlen;
return t->nodes[ni].val;
}
int
trielookup(Trie *t, char *key, int klen, char **val, int *vlen)
{
int ni;
int i;
ni = t->root;
for(i = 0; i < klen; i++){
ni = find(t, ni, key[i]);
if(ni < 0)
return 0;
}
if(val != nil && t->nodes[ni].val != nil){
*val = t->nodes[ni].val;
*vlen = t->nodes[ni].vlen;
}
return 1;
}