root/decorate.c

DEFINITIONS

1. hash_obj
2. insert_decoration
3. grow_decoration
4. add_decoration
5. lookup_decoration

/*
 * decorate.c - decorate a git object with some arbitrary
 * data.
 */
#include "cache.h"
#include "object.h"
#include "decorate.h"

static unsigned int hash_obj(const struct object *obj, unsigned int n)
{
        return sha1hash(obj->sha1) % n;
}

static void *insert_decoration(struct decoration *n, const struct object *base, void *decoration)
{
        int size = n->size;
        struct object_decoration *hash = n->hash;
        unsigned int j = hash_obj(base, size);

        while (hash[j].base) {
                if (hash[j].base == base) {
                        void *old = hash[j].decoration;
                        hash[j].decoration = decoration;
                        return old;
                }
                if (++j >= size)
                        j = 0;
        }
        hash[j].base = base;
        hash[j].decoration = decoration;
        n->nr++;
        return NULL;
}

static void grow_decoration(struct decoration *n)
{
        int i;
        int old_size = n->size;
        struct object_decoration *old_hash = n->hash;

        n->size = (old_size + 1000) * 3 / 2;
        n->hash = xcalloc(n->size, sizeof(struct object_decoration));
        n->nr = 0;

        for (i = 0; i < old_size; i++) {
                const struct object *base = old_hash[i].base;
                void *decoration = old_hash[i].decoration;

                if (!decoration)
                        continue;
                insert_decoration(n, base, decoration);
        }
        free(old_hash);
}

/* Add a decoration pointer, return any old one */
void *add_decoration(struct decoration *n, const struct object *obj,
                void *decoration)
{
        int nr = n->nr + 1;

        if (nr > n->size * 2 / 3)
                grow_decoration(n);
        return insert_decoration(n, obj, decoration);
}

/* Lookup a decoration pointer */
void *lookup_decoration(struct decoration *n, const struct object *obj)
{
        unsigned int j;

        /* nothing to lookup */
        if (!n->size)
                return NULL;
        j = hash_obj(obj, n->size);
        for (;;) {
                struct object_decoration *ref = n->hash + j;
                if (ref->base == obj)
                        return ref->decoration;
                if (!ref->base)
                        return NULL;
                if (++j == n->size)
                        j = 0;
        }
}