[OAK-1110] Make NodeStateDiff composable

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Won't Fix
• Component/s: core
• Assignee: Michael Dürig
• Reporter: Michael Dürig
• Created: 23/Oct/13 14:00
• Updated: 16/Apr/14 19:42
• Resolved: 24/Oct/13 09:07

Description

Currently it is not possible to warp a NodeStateDiff instance into another one for delegation. The problem is that recursion is done by the consumer of the childNodeChanged() call back which causes wrapped NodeStateDiff "to escape". To fix that I propose to separate the concerns of change notification from recursing into a subtree. For this we need an extra method createChildDiff on the NodeStateDiff interface:

    /**
     * Create a {@code NodeStateDiff} for diffing the passed {@code before} and
     * {@code after} states. Returning {@code null} skips comparison for the sub
     * trees rooted at the passed states.
     *
     * @param name  name of the child node
     * @param before  before state of the child node
     * @param after   after state of the child node
     * @return  {@code NodeStateDiff} for the child node
     */
    @CheckForNull
    NodeStateDiff createChildDiff(String name, NodeState before, NodeState after);

Issue Links

• blocks: OAK-783 Reflect Move and Rename upon Root#commit