qobject/qdict.c

/*
 * QDict Module
 *
 * Copyright (C) 2009 Red Hat Inc.
 *
 * Authors:
 *  Luiz Capitulino <lcapitulino@redhat.com>
 *
 * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
 * See the COPYING.LIB file in the top-level directory.
 */

#include "qemu/osdep.h"
#include "qapi/qmp/qnum.h"
#include "qapi/qmp/qdict.h"
#include "qapi/qmp/qbool.h"
#include "qapi/qmp/qnull.h"
#include "qapi/qmp/qstring.h"
#include "qobject-internal.h"

/**
 * qdict_new(): Create a new QDict
 *
 * Return strong reference.
 */
QDict *qdict_new(void)
{
    QDict *qdict;

    qdict = g_malloc0(sizeof(*qdict));
    qobject_init(QOBJECT(qdict), QTYPE_QDICT);

    return qdict;
}

/**
 * tdb_hash(): based on the hash algorithm from gdbm, via tdb
 * (from module-init-tools)
 */
static unsigned int tdb_hash(const char *name)
{
    unsigned value;    /* Used to compute the hash value.  */
    unsigned   i;      /* Used to cycle through random values. */

    /* Set the initial value from the key size. */
    for (value = 0x238F13AF * strlen(name), i = 0; name[i]; i++) {
        value = (value + (((const unsigned char *)name)[i] << (i * 5 % 24)));
    }

    return (1103515243 * value + 12345);
}

/**
 * alloc_entry(): allocate a new QDictEntry
 */
static QDictEntry *alloc_entry(const char *key, QObject *value)
{
    QDictEntry *entry;

    entry = g_malloc0(sizeof(*entry));
    entry->key = g_strdup(key);
    entry->value = value;

    return entry;
}

/**
 * qdict_entry_value(): Return qdict entry value
 *
 * Return weak reference.
 */
QObject *qdict_entry_value(const QDictEntry *entry)
{
    return entry->value;
}

/**
 * qdict_entry_key(): Return qdict entry key
 *
 * Return a *pointer* to the string, it has to be duplicated before being
 * stored.
 */
const char *qdict_entry_key(const QDictEntry *entry)
{
    return entry->key;
}

/**
 * qdict_find(): List lookup function
 */
static QDictEntry *qdict_find(const QDict *qdict,
                              const char *key, unsigned int bucket)
{
    QDictEntry *entry;

    QLIST_FOREACH(entry, &qdict->table[bucket], next)
        if (!strcmp(entry->key, key)) {
            return entry;
        }

    return NULL;
}

/**
 * qdict_put_obj(): Put a new QObject into the dictionary
 *
 * Insert the pair 'key:value' into 'qdict', if 'key' already exists
 * its 'value' will be replaced.
 *
 * This is done by freeing the reference to the stored QObject and
 * storing the new one in the same entry.
 *
 * NOTE: ownership of 'value' is transferred to the QDict
 */
void qdict_put_obj(QDict *qdict, const char *key, QObject *value)
{
    unsigned int bucket;
    QDictEntry *entry;

    bucket = tdb_hash(key) % QDICT_BUCKET_MAX;
    entry = qdict_find(qdict, key, bucket);
    if (entry) {
        /* replace key's value */
        qobject_unref(entry->value);
        entry->value = value;
    } else {
        /* allocate a new entry */
        entry = alloc_entry(key, value);
        QLIST_INSERT_HEAD(&qdict->table[bucket], entry, next);
        qdict->size++;
    }
}

void qdict_put_int(QDict *qdict, const char *key, int64_t value)
{
    qdict_put(qdict, key, qnum_from_int(value));
}

void qdict_put_bool(QDict *qdict, const char *key, bool value)
{
    qdict_put(qdict, key, qbool_from_bool(value));
}

void qdict_put_str(QDict *qdict, const char *key, const char *value)
{
    qdict_put(qdict, key, qstring_from_str(value));
}

void qdict_put_null(QDict *qdict, const char *key)
{
    qdict_put(qdict, key, qnull());
}

/**
 * qdict_get(): Lookup for a given 'key'
 *
 * Return a weak reference to the QObject associated with 'key' if
 * 'key' is present in the dictionary, NULL otherwise.
 */
QObject *qdict_get(const QDict *qdict, const char *key)
{
    QDictEntry *entry;

    entry = qdict_find(qdict, key, tdb_hash(key) % QDICT_BUCKET_MAX);
    return (entry == NULL ? NULL : entry->value);
}

/**
 * qdict_haskey(): Check if 'key' exists
 *
 * Return 1 if 'key' exists in the dict, 0 otherwise
 */
int qdict_haskey(const QDict *qdict, const char *key)
{
    unsigned int bucket = tdb_hash(key) % QDICT_BUCKET_MAX;
    return (qdict_find(qdict, key, bucket) == NULL ? 0 : 1);
}

/**
 * qdict_size(): Return the size of the dictionary
 */
size_t qdict_size(const QDict *qdict)
{
    return qdict->size;
}

/**
 * qdict_get_double(): Get an number mapped by 'key'
 *
 * This function assumes that 'key' exists and it stores a QNum.
 *
 * Return number mapped by 'key'.
 */
double qdict_get_double(const QDict *qdict, const char *key)
{
    return qnum_get_double(qobject_to(QNum, qdict_get(qdict, key)));
}

/**
 * qdict_get_int(): Get an integer mapped by 'key'
 *
 * This function assumes that 'key' exists and it stores a
 * QNum representable as int.
 *
 * Return integer mapped by 'key'.
 */
int64_t qdict_get_int(const QDict *qdict, const char *key)
{
    return qnum_get_int(qobject_to(QNum, qdict_get(qdict, key)));
}

/**
 * qdict_get_bool(): Get a bool mapped by 'key'
 *
 * This function assumes that 'key' exists and it stores a
 * QBool object.
 *
 * Return bool mapped by 'key'.
 */
bool qdict_get_bool(const QDict *qdict, const char *key)
{
    return qbool_get_bool(qobject_to(QBool, qdict_get(qdict, key)));
}

/**
 * qdict_get_qlist(): If @qdict maps @key to a QList, return it, else NULL.
 */
QList *qdict_get_qlist(const QDict *qdict, const char *key)
{
    return qobject_to(QList, qdict_get(qdict, key));
}

/**
 * qdict_get_qdict(): If @qdict maps @key to a QDict, return it, else NULL.
 */
QDict *qdict_get_qdict(const QDict *qdict, const char *key)
{
    return qobject_to(QDict, qdict_get(qdict, key));
}

/**
 * qdict_get_str(): Get a pointer to the stored string mapped
 * by 'key'
 *
 * This function assumes that 'key' exists and it stores a
 * QString object.
 *
 * Return pointer to the string mapped by 'key'.
 */
const char *qdict_get_str(const QDict *qdict, const char *key)
{
    return qstring_get_str(qobject_to(QString, qdict_get(qdict, key)));
}

/**
 * qdict_get_try_int(): Try to get integer mapped by 'key'
 *
 * Return integer mapped by 'key', if it is not present in the
 * dictionary or if the stored object is not a QNum representing an
 * integer, 'def_value' will be returned.
 */
int64_t qdict_get_try_int(const QDict *qdict, const char *key,
                          int64_t def_value)
{
    QNum *qnum = qobject_to(QNum, qdict_get(qdict, key));
    int64_t val;

    if (!qnum || !qnum_get_try_int(qnum, &val)) {
        return def_value;
    }

    return val;
}

/**
 * qdict_get_try_bool(): Try to get a bool mapped by 'key'
 *
 * Return bool mapped by 'key', if it is not present in the
 * dictionary or if the stored object is not of QBool type
 * 'def_value' will be returned.
 */
bool qdict_get_try_bool(const QDict *qdict, const char *key, bool def_value)
{
    QBool *qbool = qobject_to(QBool, qdict_get(qdict, key));

    return qbool ? qbool_get_bool(qbool) : def_value;
}

/**
 * qdict_get_try_str(): Try to get a pointer to the stored string
 * mapped by 'key'
 *
 * Return a pointer to the string mapped by 'key', if it is not present
 * in the dictionary or if the stored object is not of QString type
 * NULL will be returned.
 */
const char *qdict_get_try_str(const QDict *qdict, const char *key)
{
    QString *qstr = qobject_to(QString, qdict_get(qdict, key));

    return qstr ? qstring_get_str(qstr) : NULL;
}

static QDictEntry *qdict_next_entry(const QDict *qdict, int first_bucket)
{
    int i;

    for (i = first_bucket; i < QDICT_BUCKET_MAX; i++) {
        if (!QLIST_EMPTY(&qdict->table[i])) {
            return QLIST_FIRST(&qdict->table[i]);
        }
    }

    return NULL;
}

/**
 * qdict_first(): Return first qdict entry for iteration.
 */
const QDictEntry *qdict_first(const QDict *qdict)
{
    return qdict_next_entry(qdict, 0);
}

/**
 * qdict_next(): Return next qdict entry in an iteration.
 */
const QDictEntry *qdict_next(const QDict *qdict, const QDictEntry *entry)
{
    QDictEntry *ret;

    ret = QLIST_NEXT(entry, next);
    if (!ret) {
        unsigned int bucket = tdb_hash(entry->key) % QDICT_BUCKET_MAX;
        ret = qdict_next_entry(qdict, bucket + 1);
    }

    return ret;
}

/**
 * qdict_clone_shallow(): Clones a given QDict. Its entries are not copied, but
 * another reference is added.
 */
QDict *qdict_clone_shallow(const QDict *src)
{
    QDict *dest;
    QDictEntry *entry;
    int i;

    dest = qdict_new();

    for (i = 0; i < QDICT_BUCKET_MAX; i++) {
        QLIST_FOREACH(entry, &src->table[i], next) {
            qdict_put_obj(dest, entry->key, qobject_ref(entry->value));
        }
    }

    return dest;
}

/**
 * qentry_destroy(): Free all the memory allocated by a QDictEntry
 */
static void qentry_destroy(QDictEntry *e)
{
    assert(e != NULL);
    assert(e->key != NULL);
    assert(e->value != NULL);

    qobject_unref(e->value);
    g_free(e->key);
    g_free(e);
}

/**
 * qdict_del(): Delete a 'key:value' pair from the dictionary
 *
 * This will destroy all data allocated by this entry.
 */
void qdict_del(QDict *qdict, const char *key)
{
    QDictEntry *entry;

    entry = qdict_find(qdict, key, tdb_hash(key) % QDICT_BUCKET_MAX);
    if (entry) {
        QLIST_REMOVE(entry, next);
        qentry_destroy(entry);
        qdict->size--;
    }
}

/**
 * qdict_is_equal(): Test whether the two QDicts are equal
 *
 * Here, equality means whether they contain the same keys and whether
 * the respective values are in turn equal (i.e. invoking
 * qobject_is_equal() on them yields true).
 */
bool qdict_is_equal(const QObject *x, const QObject *y)
{
    const QDict *dict_x = qobject_to(QDict, x);
    const QDict *dict_y = qobject_to(QDict, y);
    const QDictEntry *e;

    if (qdict_size(dict_x) != qdict_size(dict_y)) {
        return false;
    }

    for (e = qdict_first(dict_x); e; e = qdict_next(dict_x, e)) {
        const QObject *obj_x = qdict_entry_value(e);
        const QObject *obj_y = qdict_get(dict_y, qdict_entry_key(e));

        if (!qobject_is_equal(obj_x, obj_y)) {
            return false;
        }
    }

    return true;
}

/**
 * qdict_destroy_obj(): Free all the memory allocated by a QDict
 */
void qdict_destroy_obj(QObject *obj)
{
    int i;
    QDict *qdict;

    assert(obj != NULL);
    qdict = qobject_to(QDict, obj);

    for (i = 0; i < QDICT_BUCKET_MAX; i++) {
        QDictEntry *entry = QLIST_FIRST(&qdict->table[i]);
        while (entry) {
            QDictEntry *tmp = QLIST_NEXT(entry, next);
            QLIST_REMOVE(entry, next);
            qentry_destroy(entry);
            entry = tmp;
        }
    }

    g_free(qdict);
}