Filter

Overview

Collects unique AST nodes matching configurable criteria (kinds, tags, parent/child inclusion). Deduplicates by USR and provides bulk filtering operations.

Why Use This?

When collecting nodes across multiple files or ASTs, you need deduplication and consistent filtering rules. filter encapsulates common patterns like kind whitelists, multi-tag logic, and parent propagation into a reusable config.

Types

Type	Description
filter	Container of unique node_ptr (deduplicated by USR)
filter::config	Filtering rules (kinds, tags, inclusion modes)
filter::config::node_inclusion	Enum: exclude, include, include_recursively

filter::config Fields

Field	Type	Description
allowed_kinds	std::vector<node::kind>	Whitelist of node kinds (empty = all)
grab_tag_names	std::vector<std::string>	Include nodes with any of these tags
avoid_tag_names	std::vector<std::string>	Exclude nodes with any of these tags
child_node_inclusion	node_inclusion	How to handle children of matched nodes
parent_node_inclusion	node_inclusion	How to handle parents of matched nodes

Functions

filter()

Default constructor. No filtering rules.

filter(cfg)

Construct with filtering configuration.

Signature: filter(const config& cfg)

add

Add a node to the filter. Rejects duplicates by USR.

Signature: bool add(const node_ptr& type)

Returns: true if added, false if already exists or invalid

remove

Remove a node from the filter.

Signature: bool remove(const node_ptr& type)

Returns: true if removed, false if not found

clean

Remove all nodes that don’t match the full config criteria.

Signature: filter& clean()

Returns: *this for chaining

Notes: Call after bulk insertion. add() performs basic validation; clean() applies the full config (parent/child rules).

contains

Check if a node is in the filter (by USR).

Signature: bool contains(const node_ptr& type) const

clear

Remove all nodes.

Signature: filter& clear()

size

Get the number of nodes.

Signature: std::size_t size() const

empty

Check if the filter is empty.

Signature: bool empty() const

get_types

Get all collected nodes.

Signature: const std::vector<node_ptr>& get_types() const

get_config

Get the current configuration.

Signature: const config& get_config() const

is_valid_type

Check if a node passes basic kind/tag validation.

Signature: bool is_valid_type(const node_ptr& type) const

matches_config

Check if a node matches the full config criteria.

Signature: bool matches_config(const node_ptr& type) const

Notes:

• Supports range-based for loops via begin() / end() iterators.
• add() cost is O(n) scan of USR list. For >1000 nodes, consider pre-filtering with find_descendants().

Example:

xccmeta::filter::config cfg;
cfg.allowed_kinds = {xccmeta::node::kind::struct_decl, xccmeta::node::kind::class_decl};
cfg.grab_tag_names = {"reflect"};

xccmeta::filter types(cfg);
for (auto& file : imp.get_files()) {
  auto ast = parser.parse(file.read(), args);
  for (auto& node : ast->get_children()) {
    types.add(node);
  }
}
types.clean();

for (auto& type : types) {
  // Process deduplicated types
}