NodeMetaDataHandler (Groovy 6.0.0-alpha-1)

```
public interface NodeMetaDataHandler
```
An interface to mark a node being able to handle metadata.
The default newMetaDataMap() returns a ListHashMap wrapped in Collections.synchronizedMap, so concurrent compiles sharing an AST node (e.g. built-in annotation ClassNodes cached by ClassHelper) cannot trip an ArrayIndexOutOfBoundsException during the array-to-HashMap transition in ListHashMap.put. Implementers that store the map in a field should declare it volatile so the unsynchronized fast-path read in the default methods sees publish-time writes.
Since:
3.0.0

Methods Summary

Methods
Type Params	Return Type	Name and description
	`public void`	`copyNodeMetaData(NodeMetaDataHandler other)` Copies all node metadata from the other node to this one
	`public Map<?, ?>`	`getMetaDataMap()` Returns the underlying metadata map.
`<T>`	`public T`	`getNodeMetaData(Object key)` Gets the node metadata.
`<T>`	`public T`	`getNodeMetaData(Object key, Function<?, ? extends T> valFn)` Gets the node metadata.
	`public Map<?, ?>`	`getNodeMetaData()` Returns an unmodifiable snapshot of the current node metadata.
	`private public Map`	`getOrCreateMetaDataMap()` Returns the existing metadata map, creating one via newMetaDataMap() on first use.
	`public Map<?, ?>`	`newMetaDataMap()` Creates the backing metadata map.
	`public Object`	`putNodeMetaData(Object key, Object value)` Sets the node metadata but allows overwriting values.
	`public void`	`removeNodeMetaData(Object key)` Removes a node metadata entry.
	`public void`	`setMetaDataMap(Map<?, ?> metaDataMap)`
	`public void`	`setNodeMetaData(Object key, Object value)` Sets the node metadata.

- Method Detail
  - public void copyNodeMetaData(NodeMetaDataHandler other)
    
    Copies all node metadata from the other node to this one
    Parameters:
    other - the other node
  - public Map<?, ?> getMetaDataMap()
    
    Returns the underlying metadata map. The map returned by the default newMetaDataMap() is internally synchronized, so individual get/put/remove calls are thread-safe; however, per the Collections.synchronizedMap contract, iteration over the returned map (or any of its keySet, values, or entrySet views) must be done inside a synchronized (map) { ... } block to avoid ConcurrentModificationException.
  - <T> public T getNodeMetaData(Object key)
    
    Gets the node metadata.
    Parameters:
    key - the metadata key
    Returns:
    the node metadata value for this key
  - <T> public T getNodeMetaData(Object key, Function<?, ? extends T> valFn)
    
    Gets the node metadata.
    Parameters:
    key - the metadata key
    valFn - the metadata value supplier
    Returns:
    the node metadata value for this key
  - public Map<?, ?> getNodeMetaData()
    
    Returns an unmodifiable snapshot of the current node metadata.
    Returns:
    the node metadata. Always not null.
  - private public Map getOrCreateMetaDataMap()
    
    Returns the existing metadata map, creating one via newMetaDataMap() on first use. Lazy creation is guarded by a brief lock on this so concurrent first-callers agree on a single map; subsequent callers see the map via the (volatile) field read and skip the lock entirely.
  - public Map<?, ?> newMetaDataMap()
    
    Creates the backing metadata map. The default returns a ListHashMap wrapped in Collections.synchronizedMap for thread-safe per-entry access; subclasses may override to supply an alternative map (e.g. for different memory/concurrency trade-offs).
    Since:
    5.0.0
  - public Object putNodeMetaData(Object key, Object value)
    
    Sets the node metadata but allows overwriting values.
    throws:
    GroovyBugError if key is null
    
    Parameters:
    key - the metadata key
    value - the metadata value
    Returns:
    the old node metadata value for this key
  - public void removeNodeMetaData(Object key)
    
    Removes a node metadata entry.
    throws:
    GroovyBugError if the key is null
    
    Parameters:
    key - the metadata key
  - public void setMetaDataMap(Map<?, ?> metaDataMap)
  - public void setNodeMetaData(Object key, Object value)
    
    Sets the node metadata.
    throws:
    GroovyBugError if key is null or there is already metadata for key
    
    Parameters:
    key - the metadata key
    value - the metadata value

Summary:
Method

| Detail:
Method

[Java] Interface NodeMetaDataHandler

Methods Summary

Method Detail

public void copyNodeMetaData(NodeMetaDataHandler other)

public Map<?, ?> getMetaDataMap()

<T> public T getNodeMetaData(Object key)

<T> public T getNodeMetaData(Object key, Function<?, ? extends T> valFn)

public Map<?, ?> getNodeMetaData()

private public Map getOrCreateMetaDataMap()

public Map<?, ?> newMetaDataMap()

public Object putNodeMetaData(Object key, Object value)

public void removeNodeMetaData(Object key)

public void setMetaDataMap(Map<?, ?> metaDataMap)

public void setNodeMetaData(Object key, Object value)