Support optional conditions on creating fans

This adds the functional infrastructure to optionally attach a condition
function to a fan definition. When a condition is defined on a fan, it
must be true for a fan's associated functional properties to be created.
When the given condition fails, that fan's functional properties will
not be created by fan monitor. A fan without a defined condition will
have all of its associated functional properties created.

Example of generated condition (generation commit to follow):

make_condition(condition::propertiesMatch(
    std::vector<PropertyState>{
        PropertyState{
            PropertyIdentity{
                "/xyz/openbmc_project/inventory/system/chassis",
                "xyz.openbmc_project.Inventory.Decorator.CoolingType",
                "WaterCooled"
            },
            static_cast<bool>(false)
        }
    }
)),

Tested:
    Fan functional properties are not created when a condition fails
    Fan functional properties are created when condition passes
    Fan functional properties are created when no condition exists

Change-Id: I9ced2e520d2f97e6655c9417970b3e976d78fef4
Signed-off-by: Matthew Barth <msbarth@us.ibm.com>

1 files changed, 43 insertions, 0 deletions

diff --git a/monitor/conditions.hpp b/monitor/conditions.hpp
new file mode 100644
index 0000000..76aa0de
--- /dev/null
+++ b/monitor/conditions.hpp
@@ -0,0 +1,43 @@
+#pragma once
+
+#include "types.hpp"
+
+namespace phosphor
+{
+namespace fan
+{
+namespace monitor
+{
+
+/**
+ * @brief Create a condition function object
+ *
+ * @param[in] condition - The condition being created
+ *
+ * @return - The created condition function object
+ */
+template <typename T>
+auto make_condition(T&& condition)
+{
+    return Condition(std::forward<T>(condition));
+}
+
+namespace condition
+{
+
+/**
+ * @brief A condition that checks all properties match the given values
+ * @details Checks each property entry against its given value where all
+ * property values must match their given value for the condition to pass
+ *
+ * @param[in] propStates - List of property identifiers and their value
+ *
+ * @return Condition lambda function
+ *     A Condition function that checks all properties match
+ */
+Condition propertiesMatch(std::vector<PropertyState>&& propStates);
+
+} // namespace condition
+} // namespace monitor
+} // namespace fan
+} // namespace phosphor