Code

store: Added support for regex matchers.
[sysdb.git] / src / core / store_lookup.c
index 0bb157c76e7a49162e3832f5b9ae0e013372485a..a86743e7cedc4d2fff72c950f580bce0925dc00d 100644 (file)
@@ -55,6 +55,7 @@
 
 typedef struct {
        sdb_store_matcher_t *m;
+       sdb_store_matcher_t *filter;
        sdb_store_lookup_cb  cb;
        void *user_data;
 } scan_iter_data_t;
@@ -68,13 +69,13 @@ scan_iter(sdb_store_obj_t *obj, void *user_data)
 {
        scan_iter_data_t *d = user_data;
 
-       if (sdb_store_matcher_matches(d->m, obj))
+       if (sdb_store_matcher_matches(d->m, obj, d->filter))
                return d->cb(obj, d->user_data);
        return 0;
 } /* scan_iter */
 
 static sdb_attribute_t *
-attr_get(sdb_host_t *host, const char *name)
+attr_get(sdb_host_t *host, const char *name, sdb_store_matcher_t *filter)
 {
        sdb_avltree_iter_t *iter = NULL;
        sdb_attribute_t *attr = NULL;
@@ -91,6 +92,10 @@ attr_get(sdb_host_t *host, const char *name)
                break;
        }
        sdb_avltree_iter_destroy(iter);
+
+       if (filter && (! sdb_store_matcher_matches(filter, STORE_OBJ(attr),
+                                       NULL)))
+               return NULL;
        return attr;
 } /* attr_get */
 
@@ -99,18 +104,74 @@ attr_get(sdb_host_t *host, const char *name)
  */
 
 static int
-attr_cmp(sdb_host_t *host, sdb_store_cond_t *cond)
+attr_cmp(sdb_store_obj_t *obj, sdb_store_cond_t *cond,
+               sdb_store_matcher_t *filter)
 {
        sdb_attribute_t *attr;
+       sdb_data_t value = SDB_DATA_INIT;
+       int status;
 
-       attr = attr_get(host, ATTR_C(cond)->name);
-       if (! attr)
+       if (obj->type != SDB_HOST)
                return INT_MAX;
-       if (attr->value.type != ATTR_C(cond)->value.type)
+
+       if (sdb_store_expr_eval(ATTR_C(cond)->expr, obj, &value, filter))
                return INT_MAX;
-       return sdb_data_cmp(&attr->value, &ATTR_C(cond)->value);
+
+       attr = attr_get(HOST(obj), ATTR_C(cond)->name, filter);
+       if (! attr)
+               status = INT_MAX;
+       else if (attr->value.type != value.type)
+               status = sdb_data_strcmp(&attr->value, &value);
+       else
+               status = sdb_data_cmp(&attr->value, &value);
+       sdb_data_free_datum(&value);
+       return status;
 } /* attr_cmp */
 
+static int
+obj_cmp(sdb_store_obj_t *obj, sdb_store_cond_t *cond,
+               sdb_store_matcher_t *filter)
+{
+       sdb_data_t obj_value = SDB_DATA_INIT;
+       sdb_data_t value = SDB_DATA_INIT;
+       int status;
+
+       if (sdb_store_expr_eval(OBJ_C(cond)->expr, obj, &value, filter))
+               return INT_MAX;
+
+       if (OBJ_C(cond)->field == SDB_FIELD_BACKEND) {
+               /* this implementation is not actually a conditional but rather checks
+                * for equality (or rather, existence) only */
+               size_t i;
+
+               if (value.type != SDB_TYPE_STRING)
+                       return INT_MAX;
+
+               status = INT_MAX;
+               for (i = 0; i < obj->backends_num; ++i) {
+                       if (! strcasecmp(obj->backends[i], value.data.string)) {
+                               status = 0;
+                               break;
+                       }
+               }
+               sdb_data_free_datum(&value);
+               return status;
+       }
+
+       if (sdb_store_get_field(obj, OBJ_C(cond)->field, &obj_value))
+               return INT_MAX;
+       if (obj_value.type != value.type) {
+               sdb_data_free_datum(&obj_value);
+               sdb_data_free_datum(&value);
+               return INT_MAX;
+       }
+
+       status = sdb_data_cmp(&obj_value, &value);
+       sdb_data_free_datum(&obj_value);
+       sdb_data_free_datum(&value);
+       return status;
+} /* obj_cmp */
+
 /*
  * matcher implementations
  */
@@ -133,54 +194,66 @@ match_string(string_matcher_t *m, const char *name)
 } /* match_string */
 
 static int
-match_logical(sdb_store_matcher_t *m, sdb_host_t *host)
+match_logical(sdb_store_matcher_t *m, sdb_store_obj_t *obj,
+               sdb_store_matcher_t *filter)
 {
        int status;
 
        assert((m->type == MATCHER_AND) || (m->type == MATCHER_OR));
        assert(OP_M(m)->left && OP_M(m)->right);
 
-       status = sdb_store_matcher_matches(OP_M(m)->left, STORE_OBJ(host));
+       status = sdb_store_matcher_matches(OP_M(m)->left, obj, filter);
+
        /* lazy evaluation */
        if ((! status) && (m->type == MATCHER_AND))
                return status;
        else if (status && (m->type == MATCHER_OR))
                return status;
 
-       return sdb_store_matcher_matches(OP_M(m)->right, STORE_OBJ(host));
+       return sdb_store_matcher_matches(OP_M(m)->right, obj, filter);
 } /* match_logical */
 
 static int
-match_unary(sdb_store_matcher_t *m, sdb_host_t *host)
+match_unary(sdb_store_matcher_t *m, sdb_store_obj_t *obj,
+               sdb_store_matcher_t *filter)
 {
        assert(m->type == MATCHER_NOT);
        assert(UOP_M(m)->op);
 
-       return !sdb_store_matcher_matches(UOP_M(m)->op, STORE_OBJ(host));
+       return !sdb_store_matcher_matches(UOP_M(m)->op, obj, filter);
 } /* match_unary */
 
 static int
-match_name(sdb_store_matcher_t *m, sdb_host_t *host)
+match_name(sdb_store_matcher_t *m, sdb_store_obj_t *obj,
+               sdb_store_matcher_t *filter)
 {
        sdb_avltree_iter_t *iter = NULL;
        int status = 0;
 
        assert(m->type == MATCHER_NAME);
 
+       if (obj->type == NAME_M(m)->obj_type)
+               return match_string(&NAME_M(m)->name, SDB_OBJ(obj)->name);
+       else if (obj->type != SDB_HOST)
+               return 0;
+
        switch (NAME_M(m)->obj_type) {
-               case SDB_HOST:
-                       return match_string(&NAME_M(m)->name, SDB_OBJ(host)->name);
-                       break;
                case SDB_SERVICE:
-                       iter = sdb_avltree_get_iter(host->services);
+                       iter = sdb_avltree_get_iter(HOST(obj)->services);
+                       break;
+               case SDB_METRIC:
+                       iter = sdb_avltree_get_iter(HOST(obj)->metrics);
                        break;
                case SDB_ATTRIBUTE:
-                       iter = sdb_avltree_get_iter(host->attributes);
+                       iter = sdb_avltree_get_iter(HOST(obj)->attributes);
                        break;
        }
 
        while (sdb_avltree_iter_has_next(iter)) {
                sdb_object_t *child = sdb_avltree_iter_get_next(iter);
+               if (filter && (! sdb_store_matcher_matches(filter, STORE_OBJ(child),
+                                               NULL)))
+                       continue;
                if (match_string(&NAME_M(m)->name, child->name)) {
                        status = 1;
                        break;
@@ -191,14 +264,18 @@ match_name(sdb_store_matcher_t *m, sdb_host_t *host)
 } /* match_name */
 
 static int
-match_attr(sdb_store_matcher_t *m, sdb_host_t *host)
+match_attr(sdb_store_matcher_t *m, sdb_store_obj_t *obj,
+               sdb_store_matcher_t *filter)
 {
        sdb_attribute_t *attr;
 
        assert(m->type == MATCHER_ATTR);
        assert(ATTR_M(m)->name);
 
-       attr = attr_get(host, ATTR_M(m)->name);
+       if (obj->type != SDB_HOST)
+               return 0;
+
+       attr = attr_get(HOST(obj), ATTR_M(m)->name, filter);
        if (attr) {
                char buf[sdb_data_strlen(&attr->value) + 1];
                if (sdb_data_format(&attr->value, buf, sizeof(buf), SDB_UNQUOTED) <= 0)
@@ -210,58 +287,242 @@ match_attr(sdb_store_matcher_t *m, sdb_host_t *host)
 } /* match_attr */
 
 static int
-match_lt(sdb_store_matcher_t *m, sdb_host_t *host)
+match_child(sdb_store_matcher_t *m, sdb_store_obj_t *obj,
+               sdb_store_matcher_t *filter)
+{
+       sdb_avltree_iter_t *iter = NULL;
+       int status = 0;
+
+       assert((m->type == MATCHER_SERVICE)
+                       || (m->type == MATCHER_METRIC)
+                       || (m->type == MATCHER_ATTRIBUTE));
+
+       /* TODO: support all object types */
+       if (obj->type != SDB_HOST)
+               return 0;
+
+       if (m->type == MATCHER_SERVICE)
+               iter = sdb_avltree_get_iter(HOST(obj)->services);
+       else if (m->type == MATCHER_METRIC)
+               iter = sdb_avltree_get_iter(HOST(obj)->metrics);
+       else if (m->type == SDB_ATTRIBUTE)
+               iter = sdb_avltree_get_iter(HOST(obj)->attributes);
+
+       while (sdb_avltree_iter_has_next(iter)) {
+               sdb_object_t *child = sdb_avltree_iter_get_next(iter);
+               if (filter && (! sdb_store_matcher_matches(filter,
+                                               STORE_OBJ(child), NULL)))
+                       continue;
+
+               if (sdb_store_matcher_matches(CHILD_M(m)->m, obj, filter)) {
+                       status = 1;
+                       break;
+               }
+       }
+       sdb_avltree_iter_destroy(iter);
+       return status;
+} /* match_child */
+
+static int
+match_lt(sdb_store_matcher_t *m, sdb_store_obj_t *obj,
+               sdb_store_matcher_t *filter)
 {
        int status;
        assert(m->type == MATCHER_LT);
-       status = COND_M(m)->cond->cmp(host, COND_M(m)->cond);
+       status = COND_M(m)->cond->cmp(obj, COND_M(m)->cond, filter);
        return (status != INT_MAX) && (status < 0);
 } /* match_lt */
 
 static int
-match_le(sdb_store_matcher_t *m, sdb_host_t *host)
+match_le(sdb_store_matcher_t *m, sdb_store_obj_t *obj,
+               sdb_store_matcher_t *filter)
 {
        int status;
        assert(m->type == MATCHER_LE);
-       status = COND_M(m)->cond->cmp(host, COND_M(m)->cond);
+       status = COND_M(m)->cond->cmp(obj, COND_M(m)->cond, filter);
        return (status != INT_MAX) && (status <= 0);
 } /* match_le */
 
 static int
-match_eq(sdb_store_matcher_t *m, sdb_host_t *host)
+match_eq(sdb_store_matcher_t *m, sdb_store_obj_t *obj,
+               sdb_store_matcher_t *filter)
 {
        int status;
        assert(m->type == MATCHER_EQ);
-       status = COND_M(m)->cond->cmp(host, COND_M(m)->cond);
+       status = COND_M(m)->cond->cmp(obj, COND_M(m)->cond, filter);
        return (status != INT_MAX) && (! status);
 } /* match_eq */
 
 static int
-match_ge(sdb_store_matcher_t *m, sdb_host_t *host)
+match_ge(sdb_store_matcher_t *m, sdb_store_obj_t *obj,
+               sdb_store_matcher_t *filter)
 {
        int status;
        assert(m->type == MATCHER_GE);
-       status = COND_M(m)->cond->cmp(host, COND_M(m)->cond);
+       status = COND_M(m)->cond->cmp(obj, COND_M(m)->cond, filter);
        return (status != INT_MAX) && (status >= 0);
 } /* match_ge */
 
 static int
-match_gt(sdb_store_matcher_t *m, sdb_host_t *host)
+match_gt(sdb_store_matcher_t *m, sdb_store_obj_t *obj,
+               sdb_store_matcher_t *filter)
 {
        int status;
        assert(m->type == MATCHER_GT);
-       status = COND_M(m)->cond->cmp(host, COND_M(m)->cond);
+       status = COND_M(m)->cond->cmp(obj, COND_M(m)->cond, filter);
        return (status != INT_MAX) && (status > 0);
 } /* match_gt */
 
+/*
+ * cmp_expr:
+ * Compare the values of two expressions when evaluating them using the
+ * specified stored object and filter. Returns a value less than, equal to, or
+ * greater than zero if the value of the first expression compares less than,
+ * equal to, or greater than the value of the second expression. Returns
+ * INT_MAX if any of the expressions could not be evaluated.
+ */
+static int
+cmp_expr(sdb_store_expr_t *e1, sdb_store_expr_t *e2,
+               sdb_store_obj_t *obj, sdb_store_matcher_t *filter)
+{
+       sdb_data_t v1 = SDB_DATA_INIT, v2 = SDB_DATA_INIT;
+       int status;
+
+       if (sdb_store_expr_eval(e1, obj, &v1, filter))
+               return INT_MAX;
+       if (sdb_store_expr_eval(e2, obj, &v2, filter)) {
+               sdb_data_free_datum(&v1);
+               return INT_MAX;
+       }
+
+       if (v1.type == v2.type)
+               status = sdb_data_cmp(&v1, &v2);
+       else
+               status = sdb_data_strcmp(&v1, &v2);
+
+       sdb_data_free_datum(&v1);
+       sdb_data_free_datum(&v2);
+       return status;
+} /* cmp_expr */
+
+static int
+match_cmp_lt(sdb_store_matcher_t *m, sdb_store_obj_t *obj,
+               sdb_store_matcher_t *filter)
+{
+       int status;
+       assert(m->type == MATCHER_CMP_LT);
+       status = cmp_expr(CMP_M(m)->left, CMP_M(m)->right, obj, filter);
+       return (status != INT_MAX) && (status < 0);
+} /* match_cmp_lt */
+
+static int
+match_cmp_le(sdb_store_matcher_t *m, sdb_store_obj_t *obj,
+               sdb_store_matcher_t *filter)
+{
+       int status;
+       assert(m->type == MATCHER_CMP_LE);
+       status = cmp_expr(CMP_M(m)->left, CMP_M(m)->right, obj, filter);
+       return (status != INT_MAX) && (status <= 0);
+} /* match_cmp_le */
+
+static int
+match_cmp_eq(sdb_store_matcher_t *m, sdb_store_obj_t *obj,
+               sdb_store_matcher_t *filter)
+{
+       int status;
+       assert(m->type == MATCHER_CMP_EQ);
+       status = cmp_expr(CMP_M(m)->left, CMP_M(m)->right, obj, filter);
+       return (status != INT_MAX) && (! status);
+} /* match_cmp_eq */
+
+static int
+match_cmp_ge(sdb_store_matcher_t *m, sdb_store_obj_t *obj,
+               sdb_store_matcher_t *filter)
+{
+       int status;
+       assert(m->type == MATCHER_CMP_GE);
+       status = cmp_expr(CMP_M(m)->left, CMP_M(m)->right, obj, filter);
+       return (status != INT_MAX) && (status >= 0);
+} /* match_cmp_ge */
+
+static int
+match_cmp_gt(sdb_store_matcher_t *m, sdb_store_obj_t *obj,
+               sdb_store_matcher_t *filter)
+{
+       int status;
+       assert(m->type == MATCHER_CMP_GT);
+       status = cmp_expr(CMP_M(m)->left, CMP_M(m)->right, obj, filter);
+       return (status != INT_MAX) && (status > 0);
+} /* match_cmp_gt */
+
+static int
+match_regex(sdb_store_matcher_t *m, sdb_store_obj_t *obj,
+               sdb_store_matcher_t *filter)
+{
+       sdb_data_t v = SDB_DATA_INIT;
+       int status = 0;
+
+       regex_t regex;
+       _Bool free_regex = 0;
+
+       assert(m->type == MATCHER_REGEX);
+
+       if (! CMP_M(m)->right->type) {
+               assert(CMP_M(m)->right->data.type == SDB_TYPE_REGEX);
+               regex = CMP_M(m)->right->data.data.re.regex;
+       }
+       else {
+               sdb_data_t tmp = SDB_DATA_INIT;
+               char *raw;
+
+               if (sdb_store_expr_eval(CMP_M(m)->right, obj, &tmp, filter))
+                       return 0;
+
+               if (tmp.type != SDB_TYPE_STRING) {
+                       sdb_data_free_datum(&tmp);
+                       return 0;
+               }
+
+               raw = tmp.data.string;
+               if (sdb_data_parse(raw, SDB_TYPE_REGEX, &tmp)) {
+                       free(raw);
+                       return 0;
+               }
+
+               regex = tmp.data.re.regex;
+               free_regex = 1;
+               free(tmp.data.re.raw);
+               free(raw);
+       }
+
+       if (sdb_store_expr_eval(CMP_M(m)->left, obj, &v, filter))
+               status = 0;
+       else {
+               char value[sdb_data_strlen(&v) + 1];
+               if (sdb_data_format(&v, value, sizeof(value), SDB_UNQUOTED) < 0)
+                       status = 0;
+               else if (! regexec(&regex, value, 0, NULL, 0))
+                       status = 1;
+       }
+
+       if (free_regex)
+               regfree(&regex);
+       sdb_data_free_datum(&v);
+       return status;
+} /* match_regex */
+
 static int
-match_isnull(sdb_store_matcher_t *m, sdb_host_t *host)
+match_isnull(sdb_store_matcher_t *m, sdb_store_obj_t *obj,
+               sdb_store_matcher_t *filter)
 {
        assert(m->type == MATCHER_ISNULL);
-       return attr_get(host, ISNULL_M(m)->attr_name) == NULL;
+       if (obj->type != SDB_HOST)
+               return 0;
+       return attr_get(HOST(obj), ISNULL_M(m)->attr_name, filter) == NULL;
 } /* match_isnull */
 
-typedef int (*matcher_cb)(sdb_store_matcher_t *, sdb_host_t *);
+typedef int (*matcher_cb)(sdb_store_matcher_t *, sdb_store_obj_t *,
+               sdb_store_matcher_t *);
 
 /* this array needs to be indexable by the matcher types;
  * -> update the enum in store-private.h when updating this */
@@ -272,11 +533,20 @@ matchers[] = {
        match_unary,
        match_name,
        match_attr,
+       match_child,
+       match_child,
+       match_child,
        match_lt,
        match_le,
        match_eq,
        match_ge,
        match_gt,
+       match_cmp_lt,
+       match_cmp_le,
+       match_cmp_eq,
+       match_cmp_ge,
+       match_cmp_gt,
+       match_regex,
        match_isnull,
 };
 
@@ -288,7 +558,7 @@ static int
 attr_cond_init(sdb_object_t *obj, va_list ap)
 {
        const char *name = va_arg(ap, const char *);
-       const sdb_data_t *value = va_arg(ap, const sdb_data_t *);
+       sdb_store_expr_t *expr = va_arg(ap, sdb_store_expr_t *);
 
        if (! name)
                return -1;
@@ -298,8 +568,8 @@ attr_cond_init(sdb_object_t *obj, va_list ap)
        ATTR_C(obj)->name = strdup(name);
        if (! ATTR_C(obj)->name)
                return -1;
-       if (sdb_data_copy(&ATTR_C(obj)->value, value))
-               return -1;
+       ATTR_C(obj)->expr = expr;
+       sdb_object_ref(SDB_OBJ(expr));
        return 0;
 } /* attr_cond_init */
 
@@ -308,7 +578,7 @@ attr_cond_destroy(sdb_object_t *obj)
 {
        if (ATTR_C(obj)->name)
                free(ATTR_C(obj)->name);
-       sdb_data_free_datum(&ATTR_C(obj)->value);
+       sdb_object_deref(SDB_OBJ(ATTR_C(obj)->expr));
 } /* attr_cond_destroy */
 
 static sdb_type_t attr_cond_type = {
@@ -317,6 +587,32 @@ static sdb_type_t attr_cond_type = {
        /* destroy = */ attr_cond_destroy,
 };
 
+static int
+obj_cond_init(sdb_object_t *obj, va_list ap)
+{
+       int field = va_arg(ap, int);
+       sdb_store_expr_t *expr = va_arg(ap, sdb_store_expr_t *);
+
+       SDB_STORE_COND(obj)->cmp = obj_cmp;
+
+       OBJ_C(obj)->field = field;
+       OBJ_C(obj)->expr = expr;
+       sdb_object_ref(SDB_OBJ(expr));
+       return 0;
+} /* obj_cond_init */
+
+static void
+obj_cond_destroy(sdb_object_t *obj)
+{
+       sdb_object_deref(SDB_OBJ(OBJ_C(obj)->expr));
+} /* obj_cond_destroy */
+
+static sdb_type_t obj_cond_type = {
+       /* size = */ sizeof(obj_cond_t),
+       /* init = */ obj_cond_init,
+       /* destroy = */ obj_cond_destroy,
+};
+
 /*
  * private matcher types
  */
@@ -456,14 +752,34 @@ cond_matcher_destroy(sdb_object_t *obj)
 static char *
 cond_tostring(sdb_store_matcher_t *m, char *buf, size_t buflen)
 {
+       const char *type, *id;
+       sdb_data_t value = SDB_DATA_INIT;
+       char value_str[buflen];
+       sdb_store_expr_t *expr;
+
        if (COND_M(m)->cond->cmp == attr_cmp) {
-               char value[buflen];
-               if (sdb_data_format(&ATTR_C(COND_M(m)->cond)->value,
-                                       value, sizeof(value), SDB_SINGLE_QUOTED) < 0)
-                       snprintf(value, sizeof(value), "ERR");
-               snprintf(buf, buflen, "ATTR[%s]{ %s %s }",
-                               ATTR_C(COND_M(m)->cond)->name, MATCHER_SYM(m->type), value);
+               type = "ATTR";
+               id = ATTR_C(COND_M(m)->cond)->name;
+               expr = ATTR_C(COND_M(m)->cond)->expr;
+       }
+       else if (COND_M(m)->cond->cmp == obj_cmp) {
+               type = "OBJ";
+               id = SDB_FIELD_TO_NAME(OBJ_C(COND_M(m)->cond)->field);
+               expr = OBJ_C(COND_M(m)->cond)->expr;
        }
+       else {
+               snprintf(buf, buflen, "<unknown>");
+               return buf;
+       }
+
+       if (sdb_store_expr_eval(expr, /* obj */ NULL, &value, /* filter */ NULL))
+               snprintf(value_str, sizeof(value_str), "ERR");
+       else if (sdb_data_format(&value, value_str, sizeof(value_str),
+                               SDB_SINGLE_QUOTED) < 0)
+               snprintf(value_str, sizeof(value_str), "ERR");
+       snprintf(buf, buflen, "%s[%s]{ %s %s }", type, id,
+                       MATCHER_SYM(m->type), value_str);
+       sdb_data_free_datum(&value);
        return buf;
 } /* cond_tostring */
 
@@ -512,6 +828,71 @@ op_tostring(sdb_store_matcher_t *m, char *buf, size_t buflen)
        return buf;
 } /* op_tostring */
 
+static int
+child_matcher_init(sdb_object_t *obj, va_list ap)
+{
+       M(obj)->type = va_arg(ap, int);
+       CHILD_M(obj)->m = va_arg(ap, sdb_store_matcher_t *);
+
+       if (! CHILD_M(obj)->m)
+               return -1;
+
+       sdb_object_ref(SDB_OBJ(CHILD_M(obj)->m));
+       return 0;
+} /* child_matcher_init */
+
+static void
+child_matcher_destroy(sdb_object_t *obj)
+{
+       sdb_object_deref(SDB_OBJ(CHILD_M(obj)->m));
+} /* child_matcher_destroy */
+
+static char *
+child_tostring(sdb_store_matcher_t *m, char *buf, size_t buflen)
+{
+       snprintf(buf, buflen, "%s:", MATCHER_SYM(m->type));
+       buf[buflen - 1] = '\0';
+       sdb_store_matcher_tostring(CHILD_M(m)->m,
+                       buf + strlen(buf), buflen - strlen(buf));
+       return buf;
+} /* child_tostring */
+
+static int
+cmp_matcher_init(sdb_object_t *obj, va_list ap)
+{
+       M(obj)->type = va_arg(ap, int);
+
+       CMP_M(obj)->left = va_arg(ap, sdb_store_expr_t *);
+       sdb_object_ref(SDB_OBJ(CMP_M(obj)->left));
+       CMP_M(obj)->right = va_arg(ap, sdb_store_expr_t *);
+       sdb_object_ref(SDB_OBJ(CMP_M(obj)->right));
+
+       if ((! CMP_M(obj)->left) || (! CMP_M(obj)->right))
+               return -1;
+       return 0;
+} /* cmp_matcher_init */
+
+static void
+cmp_matcher_destroy(sdb_object_t *obj)
+{
+       sdb_object_deref(SDB_OBJ(CMP_M(obj)->left));
+       sdb_object_deref(SDB_OBJ(CMP_M(obj)->right));
+} /* cmp_matcher_destroy */
+
+static char *
+cmp_tostring(sdb_store_matcher_t *m, char *buf, size_t buflen)
+{
+       if (! m) {
+               /* this should not happen */
+               snprintf(buf, buflen, "()");
+               return buf;
+       }
+
+       /* TODO */
+       snprintf(buf, buflen, "CMP_MATCHER(%d)", m->type);
+       return buf;
+} /* cmp_tostring */
+
 static int
 uop_matcher_init(sdb_object_t *obj, va_list ap)
 {
@@ -614,6 +995,18 @@ static sdb_type_t uop_type = {
        /* destroy = */ uop_matcher_destroy,
 };
 
+static sdb_type_t child_type = {
+       /* size = */ sizeof(child_matcher_t),
+       /* init = */ child_matcher_init,
+       /* destroy = */ child_matcher_destroy,
+};
+
+static sdb_type_t cmp_type = {
+       /* size = */ sizeof(cmp_matcher_t),
+       /* init = */ cmp_matcher_init,
+       /* destroy = */ cmp_matcher_destroy,
+};
+
 static sdb_type_t isnull_type = {
        /* size = */ sizeof(isnull_matcher_t),
        /* init = */ isnull_matcher_init,
@@ -631,11 +1024,20 @@ matchers_tostring[] = {
        uop_tostring,
        name_tostring,
        attr_tostring,
+       child_tostring,
+       child_tostring,
+       child_tostring,
        cond_tostring,
        cond_tostring,
        cond_tostring,
        cond_tostring,
        cond_tostring,
+       cmp_tostring,
+       cmp_tostring,
+       cmp_tostring,
+       cmp_tostring,
+       cmp_tostring,
+       cmp_tostring,
        isnull_tostring,
 };
 
@@ -644,23 +1046,28 @@ matchers_tostring[] = {
  */
 
 sdb_store_cond_t *
-sdb_store_attr_cond(const char *name, const sdb_data_t *value)
+sdb_store_attr_cond(const char *name, sdb_store_expr_t *expr)
 {
        return SDB_STORE_COND(sdb_object_create("attr-cond", attr_cond_type,
-                               name, value));
+                               name, expr));
 } /* sdb_store_attr_cond */
 
+sdb_store_cond_t *
+sdb_store_obj_cond(int field, sdb_store_expr_t *expr)
+{
+       return SDB_STORE_COND(sdb_object_create("obj-cond", obj_cond_type,
+                               field, expr));
+} /* sdb_store_obj_cond */
+
 sdb_store_matcher_t *
 sdb_store_name_matcher(int type, const char *name, _Bool re)
 {
        sdb_store_matcher_t *m;
 
        if (re)
-               m = M(sdb_object_create("name-matcher", name_type,
-                                       NULL, name));
+               m = M(sdb_object_create("name-matcher", name_type, NULL, name));
        else
-               m = M(sdb_object_create("name-matcher", name_type,
-                                       name, NULL));
+               m = M(sdb_object_create("name-matcher", name_type, name, NULL));
 
        if (! m)
                return NULL;
@@ -672,16 +1079,34 @@ sdb_store_name_matcher(int type, const char *name, _Bool re)
 sdb_store_matcher_t *
 sdb_store_attr_matcher(const char *name, const char *value, _Bool re)
 {
+       sdb_store_matcher_t *m;
+
        if (! name)
                return NULL;
 
        if (re)
-               return M(sdb_object_create("attr-matcher", attr_type,
+               m = M(sdb_object_create("attr-matcher", attr_type,
                                        name, NULL, value));
-       return M(sdb_object_create("attr-matcher", attr_type,
-                               name, value, NULL));
+       else
+               m = M(sdb_object_create("attr-matcher", attr_type,
+                                       name, value, NULL));
+       return m;
 } /* sdb_store_attr_matcher */
 
+sdb_store_matcher_t *
+sdb_store_child_matcher(int type, sdb_store_matcher_t *m)
+{
+       if (type == SDB_SERVICE)
+               type = MATCHER_SERVICE;
+       else if (type == SDB_METRIC)
+               type = MATCHER_METRIC;
+       else if (type == SDB_ATTRIBUTE)
+               type = MATCHER_ATTRIBUTE;
+       else
+               return NULL;
+       return M(sdb_object_create("any-matcher", child_type, type, m));
+} /* sdb_store_child_matcher */
+
 sdb_store_matcher_t *
 sdb_store_lt_matcher(sdb_store_cond_t *cond)
 {
@@ -717,6 +1142,65 @@ sdb_store_gt_matcher(sdb_store_cond_t *cond)
                                MATCHER_GT, cond));
 } /* sdb_store_gt_matcher */
 
+/*
+ * TODO: Rename sdb_store_cmp_* to sdb_store_* once the old code is unused and
+ * has been removed.
+ */
+
+sdb_store_matcher_t *
+sdb_store_cmp_lt(sdb_store_expr_t *left, sdb_store_expr_t *right)
+{
+       return M(sdb_object_create("lt-matcher", cmp_type,
+                               MATCHER_CMP_LT, left, right));
+} /* sdb_store_cmp_lt */
+
+sdb_store_matcher_t *
+sdb_store_cmp_le(sdb_store_expr_t *left, sdb_store_expr_t *right)
+{
+       return M(sdb_object_create("le-matcher", cmp_type,
+                               MATCHER_CMP_LE, left, right));
+} /* sdb_store_cmp_le */
+
+sdb_store_matcher_t *
+sdb_store_cmp_eq(sdb_store_expr_t *left, sdb_store_expr_t *right)
+{
+       return M(sdb_object_create("eq-matcher", cmp_type,
+                               MATCHER_CMP_EQ, left, right));
+} /* sdb_store_cmp_eq */
+
+sdb_store_matcher_t *
+sdb_store_cmp_ge(sdb_store_expr_t *left, sdb_store_expr_t *right)
+{
+       return M(sdb_object_create("ge-matcher", cmp_type,
+                               MATCHER_CMP_GE, left, right));
+} /* sdb_store_cmp_ge */
+
+sdb_store_matcher_t *
+sdb_store_cmp_gt(sdb_store_expr_t *left, sdb_store_expr_t *right)
+{
+       return M(sdb_object_create("gt-matcher", cmp_type,
+                               MATCHER_CMP_GT, left, right));
+} /* sdb_store_cmp_gt */
+
+sdb_store_matcher_t *
+sdb_store_regex_matcher(sdb_store_expr_t *left, sdb_store_expr_t *right)
+{
+       if (! right->type) {
+               if ((right->data.type != SDB_TYPE_STRING)
+                               && (right->data.type != SDB_TYPE_REGEX))
+                       return NULL;
+
+               if (right->data.type == SDB_TYPE_STRING) {
+                       char *raw = right->data.data.string;
+                       if (sdb_data_parse(raw, SDB_TYPE_REGEX, &right->data))
+                               return NULL;
+                       free(raw);
+               }
+       }
+       return M(sdb_object_create("regex-matcher", cmp_type,
+                               MATCHER_REGEX, left, right));
+} /* sdb_store_regex_matcher */
+
 sdb_store_matcher_t *
 sdb_store_isnull_matcher(const char *attr_name)
 {
@@ -724,8 +1208,74 @@ sdb_store_isnull_matcher(const char *attr_name)
                                MATCHER_ISNULL, attr_name));
 } /* sdb_store_isnull_matcher */
 
+int
+sdb_store_parse_object_type_plural(const char *name)
+{
+       if (! strcasecmp(name, "hosts"))
+               return SDB_HOST;
+       else if (! strcasecmp(name, "services"))
+               return SDB_SERVICE;
+       else if (! strcasecmp(name, "metrics"))
+               return SDB_METRIC;
+       return -1;
+} /* sdb_store_parse_object_type_plural */
+
+int
+sdb_store_parse_field_name(const char *name)
+{
+       if (! strcasecmp(name, "name"))
+               return SDB_FIELD_NAME;
+       else if (! strcasecmp(name, "last_update"))
+               return SDB_FIELD_LAST_UPDATE;
+       else if (! strcasecmp(name, "age"))
+               return SDB_FIELD_AGE;
+       else if (! strcasecmp(name, "interval"))
+               return SDB_FIELD_INTERVAL;
+       else if (! strcasecmp(name, "backend"))
+               return SDB_FIELD_BACKEND;
+       return -1;
+} /* sdb_store_parse_field_name */
+
 static sdb_store_matcher_t *
-parse_attr_cmp(const char *attr, const char *op, const sdb_data_t *value)
+maybe_inv_matcher(sdb_store_matcher_t *m, _Bool inv)
+{
+       sdb_store_matcher_t *tmp;
+
+       if ((! m) || (! inv))
+               return m;
+
+       tmp = sdb_store_inv_matcher(m);
+       /* pass ownership to the inverse matcher */
+       sdb_object_deref(SDB_OBJ(m));
+       return tmp;
+} /* maybe_inv_matcher */
+
+static int
+parse_cond_op(const char *op,
+               sdb_store_matcher_t *(**matcher)(sdb_store_cond_t *), _Bool *inv)
+{
+       *inv = 0;
+       if (! strcasecmp(op, "<"))
+               *matcher = sdb_store_lt_matcher;
+       else if (! strcasecmp(op, "<="))
+               *matcher = sdb_store_le_matcher;
+       else if (! strcasecmp(op, "="))
+               *matcher = sdb_store_eq_matcher;
+       else if (! strcasecmp(op, ">="))
+               *matcher = sdb_store_ge_matcher;
+       else if (! strcasecmp(op, ">"))
+               *matcher = sdb_store_gt_matcher;
+       else if (! strcasecmp(op, "!=")) {
+               *matcher = sdb_store_eq_matcher;
+               *inv = 1;
+       }
+       else
+               return -1;
+       return 0;
+} /* parse_cond_op */
+
+static sdb_store_matcher_t *
+parse_attr_cmp(const char *attr, const char *op, sdb_store_expr_t *expr)
 {
        sdb_store_matcher_t *(*matcher)(sdb_store_cond_t *) = NULL;
        sdb_store_matcher_t *m;
@@ -736,64 +1286,43 @@ parse_attr_cmp(const char *attr, const char *op, const sdb_data_t *value)
                return NULL;
 
        if (! strcasecmp(op, "IS")) {
-               if (! value)
+               if (! expr)
                        return sdb_store_isnull_matcher(attr);
                else
                        return NULL;
        }
-       else if (! value)
+       else if (! expr)
                return NULL;
-       else if (! strcasecmp(op, "<"))
-               matcher = sdb_store_lt_matcher;
-       else if (! strcasecmp(op, "<="))
-               matcher = sdb_store_le_matcher;
-       else if (! strcasecmp(op, "="))
-               matcher = sdb_store_eq_matcher;
-       else if (! strcasecmp(op, ">="))
-               matcher = sdb_store_ge_matcher;
-       else if (! strcasecmp(op, ">"))
-               matcher = sdb_store_gt_matcher;
-       else if (! strcasecmp(op, "!=")) {
-               matcher = sdb_store_eq_matcher;
-               inv = 1;
-       }
-       else
+       else if (parse_cond_op(op, &matcher, &inv))
                return NULL;
 
-       cond = sdb_store_attr_cond(attr, value);
+       cond = sdb_store_attr_cond(attr, expr);
        if (! cond)
                return NULL;
 
        m = matcher(cond);
        /* pass ownership to 'm' or destroy in case of an error */
        sdb_object_deref(SDB_OBJ(cond));
-       if (! m)
-               return NULL;
-
-       if (inv) {
-               sdb_store_matcher_t *tmp;
-               tmp = sdb_store_inv_matcher(m);
-               /* pass ownership to the inverse matcher */
-               sdb_object_deref(SDB_OBJ(m));
-               m = tmp;
-       }
-       return m;
+       return maybe_inv_matcher(m, inv);
 } /* parse_attr_cmp */
 
 sdb_store_matcher_t *
 sdb_store_matcher_parse_cmp(const char *obj_type, const char *attr,
-               const char *op, const sdb_data_t *value)
+               const char *op, sdb_store_expr_t *expr)
 {
        int type = -1;
        _Bool inv = 0;
        _Bool re = 0;
 
+       sdb_data_t value = SDB_DATA_INIT;
        sdb_store_matcher_t *m = NULL;
 
        if (! strcasecmp(obj_type, "host"))
                type = SDB_HOST;
        else if (! strcasecmp(obj_type, "service"))
                type = SDB_SERVICE;
+       else if (! strcasecmp(obj_type, "metric"))
+               type = SDB_METRIC;
        else if (! strcasecmp(obj_type, "attribute"))
                type = SDB_ATTRIBUTE;
        else
@@ -814,33 +1343,60 @@ sdb_store_matcher_parse_cmp(const char *obj_type, const char *attr,
                re = 1;
        }
        else if (type == SDB_ATTRIBUTE)
-               return parse_attr_cmp(attr, op, value);
+               return parse_attr_cmp(attr, op, expr);
        else
                return NULL;
 
-       if (value->type != SDB_TYPE_STRING) {
-               if (type == SDB_ATTRIBUTE)
-                       return parse_attr_cmp(attr, op, value);
+       if (! expr)
                return NULL;
+
+       if (sdb_store_expr_eval(expr, /* obj */ NULL, &value, /* filter */ NULL)
+                       || (value.type != SDB_TYPE_STRING)) {
+               sdb_data_free_datum(&value);
+               if (type != SDB_ATTRIBUTE)
+                       return NULL;
+               return parse_attr_cmp(attr, op, expr);
        }
 
        if (! attr)
-               m = sdb_store_name_matcher(type, value->data.string, re);
+               m = sdb_store_name_matcher(type, value.data.string, re);
        else if (type == SDB_ATTRIBUTE)
-               m = sdb_store_attr_matcher(attr, value->data.string, re);
+               m = sdb_store_attr_matcher(attr, value.data.string, re);
 
-       if (! m)
+       sdb_data_free_datum(&value);
+       return maybe_inv_matcher(m, inv);
+} /* sdb_store_matcher_parse_cmp */
+
+sdb_store_matcher_t *
+sdb_store_matcher_parse_field_cmp(const char *name, const char *op,
+               sdb_store_expr_t *expr)
+{
+       sdb_store_matcher_t *(*matcher)(sdb_store_cond_t *) = NULL;
+       sdb_store_matcher_t *m;
+       sdb_store_cond_t *cond;
+       _Bool inv = 0;
+
+       int field;
+
+       if (! expr)
                return NULL;
 
-       if (inv) {
-               sdb_store_matcher_t *tmp;
-               tmp = sdb_store_inv_matcher(m);
-               /* pass ownership to the inverse matcher */
-               sdb_object_deref(SDB_OBJ(m));
-               m = tmp;
-       }
-       return m;
-} /* sdb_store_matcher_parse_cmp */
+       field = sdb_store_parse_field_name(name);
+       if (field < 0)
+               return NULL;
+
+       if (parse_cond_op(op, &matcher, &inv))
+               return NULL;
+       cond = sdb_store_obj_cond(field, expr);
+       if (! cond)
+               return NULL;
+
+       assert(matcher);
+       m = matcher(cond);
+       /* pass ownership to 'm' or destroy in case of an error */
+       sdb_object_deref(SDB_OBJ(cond));
+       return maybe_inv_matcher(m, inv);
+} /* sdb_store_matcher_parse_field_cmp */
 
 sdb_store_matcher_t *
 sdb_store_dis_matcher(sdb_store_matcher_t *left, sdb_store_matcher_t *right)
@@ -863,9 +1419,10 @@ sdb_store_inv_matcher(sdb_store_matcher_t *m)
 } /* sdb_store_inv_matcher */
 
 int
-sdb_store_matcher_matches(sdb_store_matcher_t *m, sdb_store_obj_t *obj)
+sdb_store_matcher_matches(sdb_store_matcher_t *m, sdb_store_obj_t *obj,
+               sdb_store_matcher_t *filter)
 {
-       if (obj->type != SDB_HOST)
+       if (filter && (! sdb_store_matcher_matches(filter, obj, NULL)))
                return 0;
 
        /* "NULL" always matches */
@@ -875,7 +1432,7 @@ sdb_store_matcher_matches(sdb_store_matcher_t *m, sdb_store_obj_t *obj)
        if ((m->type < 0) || ((size_t)m->type >= SDB_STATIC_ARRAY_LEN(matchers)))
                return 0;
 
-       return matchers[m->type](m, HOST(obj));
+       return matchers[m->type](m, obj, filter);
 } /* sdb_store_matcher_matches */
 
 char *
@@ -891,10 +1448,10 @@ sdb_store_matcher_tostring(sdb_store_matcher_t *m, char *buf, size_t buflen)
 } /* sdb_store_matcher_tostring */
 
 int
-sdb_store_scan(sdb_store_matcher_t *m, sdb_store_lookup_cb cb,
-               void *user_data)
+sdb_store_scan(sdb_store_matcher_t *m, sdb_store_matcher_t *filter,
+               sdb_store_lookup_cb cb, void *user_data)
 {
-       scan_iter_data_t data = { m, cb, user_data };
+       scan_iter_data_t data = { m, filter, cb, user_data };
 
        if (! cb)
                return -1;