Add basic state interface for libpod

Signed-off-by: Matthew Heon <mheon@redhat.com>

libpod/state.go

@@ -0,0 +1,37 @@
+package libpod
+
+// State is a storage backend for libpod's current state
+type State interface {
+	// Accepts full ID of container
+	GetContainer(id string) (*Container, error)
+	// Accepts full or partial IDs (as long as they are unique) and names
+	LookupContainer(idOrName string) (*Container, error)
+	// Checks if a container with the given ID is present in the state
+	HasContainer(id string) (bool, error)
+	// Adds container to state
+	// If the container belongs to a pod, that pod must already be present
+	// in the state when the container is added
+	AddContainer(ctr *Container) error
+	// Removes container from state
+	// If the container belongs to a pod, it will be removed from the pod
+	// as well
+	RemoveContainer(ctr *Container) error
+	// Retrieves all containers presently in state
+	GetAllContainers() ([]*Container, error)
+
+	// Accepts full ID of pod
+	GetPod(id string) (*Pod, error)
+	// Accepts full or partial IDs (as long as they are unique) and names
+	LookupPod(idOrName string) (*Pod, error)
+	// Checks if a pod with the given ID is present in the state
+	HasPod(id string) (bool, error)
+	// Adds pod to state
+	// Any containers within the pod not already in the state will be added
+	// with it
+	AddPod(pod *Pod) error
+	// Removes pod from state
+	// All containers within the pod will also be removed
+	RemovePod(pod *Pod) error
+	// Retrieves all pods presently in state
+	GetAllPods() ([]*Pod, error)
+}