b2/db.c: add (somewhat crude) parametric part selection

b2/db.c

@@ -296,4 +296,87 @@ struct provider *provider_add(const char *name)
 }
 
 
+/* ----- Part search (by characteristics) ---------------------------------- */
 
+
+struct sel_prm_data {
+	struct param *param;
+	const struct part **res;
+	int n_res;
+};
+
+
+static struct param *convert_vars(struct param *vars, const struct action *act)
+{
+	struct param *res = NULL, **last = &res;
+
+	convert_params(&vars, act->fields, &last);
+	convert_params(&vars, act->rules, &last);
+	free_vars(vars);
+	return res;
+}
+
+
+/*
+ * @@@ By matching fields (and not field names), we avoid having to check for
+ * field compatibility. However, this also means that only fields that appear
+ * in the same place in the hierarchy can be matched.
+ *
+ * For example, a tolerance TOL in T=R could thus never match the tolerance TOL
+ * in T=C. This seems reasonable, but may need some more pondering.
+ */
+
+/*
+ * @@@ We require all fields specified in the query to exist (and to match).
+ * Could there be cases where this doesn't make sense ?
+ */
+
+static int params_match(const struct param *query, const struct param *part)
+{
+	const struct param *q, *p;
+
+	for (q = query; q; q = q->next) {
+		for (p = part; p; p = p->next) {
+			if (q->u.field != p->u.field)
+				continue;
+			if (compare(q->u.field->fmt, &p->value, q->op,
+			   &q->value))
+				goto next;
+			return 0;
+		}
+		return 0;
+next:		;
+	}
+	return 1;
+}
+
+
+static gboolean sel_prm_traverse(gpointer key, gpointer value, gpointer data)
+{
+	struct part *p = key;
+	struct sel_prm_data *d = data;
+
+	if (!params_match(d->param, p->param))
+		return FALSE;
+	d->res = realloc(d->res, sizeof(const struct part *)*(d->n_res+1));
+	if (!d->res)
+		abort();
+	d->res[d->n_res++] = key;
+	return FALSE;
+}
+
+
+const struct part **select_parametric(struct param *vars,
+    const struct action *act)
+{
+	struct sel_prm_data data = {
+		.param = convert_vars(vars, act),
+		.res = NULL,
+		.n_res = 0,
+	};
+
+	g_tree_foreach(tree, sel_prm_traverse, (void *) &data);
+	if (data.n_res)
+		data.res[data.n_res] = NULL;
+	return data.res;
+}

b2/db.h

@@ -109,4 +109,7 @@ void currency_exchange(struct currency *from, const struct currency *to,
 struct provider *provider_lookup(const char *name);
 struct provider *provider_add(const char *name);
 
+const struct part **select_parametric(struct param *vars,
+    const struct action *act);
+
 #endif /* !DB_H */