Module dictionary 

Dictionary — string interning (§85 Phase 1).

Implements xmlDict, libxml2’s string interning mechanism for efficient string comparison and memory sharing.

UPSTREAM-PARITY

libxml2’s xmlDict is a hash-table-backed string interning dictionary. Key properties:

• Strings are interned (stored once, reused by reference)
• Interned strings are reference-counted
• Sub-dictionaries share the parent’s string table but have their own reference counting
• Dictionary limits prevent denial-of-service via excessive unique strings
• xmlDictSetLimit controls the maximum number of strings
• xmlDictGetUsage returns the current number of strings

Thread safety

xmlDict is NOT thread-safe for concurrent modification. However, concurrent reads are safe once the dictionary is populated. This matches upstream behavior.

Phase 1 status

Complete — all dictionary functions are implemented. Uses hashbrown::HashTable for the underlying hash table.

Structs

Dict

The dictionary struct (opaque in the C ABI).

Functions

dict_create

Create a new dictionary.

dict_create_sub^⚠

Create a sub-dictionary that shares strings with its parent.

dict_exists^⚠

Check if a string exists in the dictionary without adding it.

dict_free^⚠

Free a dictionary and all its interned strings.

dict_get_usage

Get the current number of entries in the dictionary.

dict_lookup^⚠

Look up a string in the dictionary, adding it if not found.

dict_set_limit

Set the maximum number of entries allowed in the dictionary.

dict_size

Get the number of entries in the dictionary.