package cascade

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package cascade
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Module Cascade.PoolSource

A mutable pool of CSS rules in cascade order, supporting near-constant merging and O(1) precedence queries.

This is the working representation for the incremental rule merger (after Hague, Lin & Hong, "CSS Minification via Constraint Solving", TOPLAS 2019):

  • order is kept by Order_maintenance, so "does rule A come before rule B?" stays O(1) as rules are inserted and removed;
  • merge classes are kept by a small in-tree union-find (path-compressed, union-by-rank, in pool.ml), so combining two rules is near-constant and a handle to an original rule still resolves to its current merged representative.

Loop drives the greedy, priority-ordered merging over this pool; its interface documents that design and the simpler batch-fixpoint alternative.

A node is a stable handle to one live rule. Combining or removing a node invalidates it; the surviving node keeps the merged rule.

Sourcetype t

A mutable pool of rules.

Sourcetype node

A stable handle to one rule in the pool.

Sourceval of_rules : Stylesheet.rule list -> t

of_rules rs builds a pool holding rs in order.

Sourceval to_rules : t -> Stylesheet.rule list

to_rules t returns the live rules in cascade order.

Sourceval nodes : t -> node list

nodes t are the live node handles in cascade order.

rule n is n's current rule (resolving through any merges).

Sourceval is_live : node -> bool

is_live n is false once n has been removed (e.g. merged away).

Sourceval id : node -> int

id n is a stable integer identity, unique in the pool and invariant under edits elsewhere, suitable for keying a priority queue of nodes.

Sourceval length : t -> int

length t is the number of live rules.

Sourceval before : node -> node -> bool

before a b is true when a precedes b in cascade order. O(1).

Sourceval next : node -> node option

next n is the rule immediately after n in cascade order.

Sourceval prev : node -> node option

prev n is the rule immediately before n in cascade order.

Sourceval set : node -> Stylesheet.rule -> unit

set n r replaces n's rule in place (e.g. a rule whose declarations shrank after factoring).

combine t a b f merges b into a: the union-find classes are unioned, the surviving rule is f (rule a) (rule b) kept at a's position, and b is removed from the order. Returns the surviving node (a's identity). a must precede b.

Sourceval insert_after : t -> node -> Stylesheet.rule -> node

insert_after t n r inserts a fresh rule r just after n (e.g. a shared factored rule) and returns its handle.

Sourceval insert_before : t -> node -> Stylesheet.rule -> node

insert_before t n r inserts a fresh rule r just before n (e.g. a shared factored rule placed ahead of the run it was hoisted from).

Sourceval remove : t -> node -> unit

remove t n deletes n from the pool.