anil.recoil.org
OCaml HTML5 parser/serialiser based on Python's JustHTML
trim
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lib/check/ancestor_tracker.ml
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lib/check/ancestor_tracker.ml
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(*---------------------------------------------------------------------------
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Copyright (c) 2025 Anil Madhavapeddy <anil@recoil.org>. All rights reserved.
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SPDX-License-Identifier: MIT
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---------------------------------------------------------------------------*)
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(** Generic ancestor tracking for DOM traversal. *)
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type 'data context = {
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name : string;
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data : 'data;
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}
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type 'data t = {
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mutable stack : 'data context list;
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}
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let create () = { stack = [] }
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let reset tracker = tracker.stack <- []
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let push tracker name data =
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let name_lower = Astring.String.Ascii.lowercase name in
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let context = { name = name_lower; data } in
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tracker.stack <- context :: tracker.stack
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let pop tracker =
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match tracker.stack with
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| [] -> () (* Gracefully handle underflow *)
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| _ :: rest -> tracker.stack <- rest
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let peek tracker =
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match tracker.stack with
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| [] -> None
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| hd :: _ -> Some hd
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let depth tracker = List.length tracker.stack
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let has_ancestor tracker name =
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let name_lower = Astring.String.Ascii.lowercase name in
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List.exists (fun ctx -> String.equal ctx.name name_lower) tracker.stack
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let has_ancestor_with tracker predicate =
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List.exists (fun ctx -> predicate ctx.name ctx.data) tracker.stack
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let find_ancestor tracker name =
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let name_lower = Astring.String.Ascii.lowercase name in
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List.find_opt (fun ctx -> String.equal ctx.name name_lower) tracker.stack
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let find_ancestor_with tracker predicate =
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List.find_opt (fun ctx -> predicate ctx.name ctx.data) tracker.stack
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let get_all_ancestors tracker = tracker.stack
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let filter_ancestors tracker predicate =
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List.filter (fun ctx -> predicate ctx.name ctx.data) tracker.stack
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let exists = has_ancestor_with
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let for_all tracker predicate =
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List.for_all (fun ctx -> predicate ctx.name ctx.data) tracker.stack
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let iter tracker f =
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List.iter (fun ctx -> f ctx.name ctx.data) tracker.stack
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let fold tracker f init =
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List.fold_left (fun acc ctx -> f acc ctx.name ctx.data) init tracker.stack
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let get_parent = peek
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let get_parent_name tracker =
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match peek tracker with
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| Some ctx -> Some ctx.name
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| None -> None
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let get_parent_data tracker =
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match peek tracker with
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| Some ctx -> Some ctx.data
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| None -> None
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let has_any_ancestor tracker names =
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let names_lower = List.map Astring.String.Ascii.lowercase names in
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List.exists (fun ctx -> List.mem ctx.name names_lower) tracker.stack
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let find_first_matching tracker names =
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let names_lower = List.map Astring.String.Ascii.lowercase names in
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List.find_map (fun ctx ->
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if List.mem ctx.name names_lower then Some (ctx.name, ctx)
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else None
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) tracker.stack
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let is_empty tracker = tracker.stack = []
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let to_list = get_all_ancestors
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let to_name_list tracker =
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List.map (fun ctx -> ctx.name) tracker.stack
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lib/check/ancestor_tracker.mli
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lib/check/ancestor_tracker.mli
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(*---------------------------------------------------------------------------
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Copyright (c) 2025 Anil Madhavapeddy <anil@recoil.org>. All rights reserved.
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SPDX-License-Identifier: MIT
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---------------------------------------------------------------------------*)
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(** Generic ancestor tracking for DOM traversal.
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This module provides a generic stack-based ancestor tracker that can be
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used by various HTML checkers to track element nesting during DOM
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traversal. It is parameterized by the type of data stored per element.
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{2 Design}
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The tracker maintains a stack of element contexts, where each context
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contains:
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- The element name (string)
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- Custom data of type ['data] (checker-specific)
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The stack is automatically managed through [push] and [pop] operations
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that should be called in response to start_element and end_element events.
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{2 Usage Example}
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{[
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(* Define custom data type *)
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type role_data = {
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explicit_roles : string list;
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implicit_role : string option;
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}
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(* Create tracker *)
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let tracker = Ancestor_tracker.create ()
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(* Push element context *)
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let data = { explicit_roles = ["button"]; implicit_role = None } in
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Ancestor_tracker.push tracker "div" data;
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(* Query ancestors *)
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let has_button = Ancestor_tracker.exists tracker
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(fun name data -> List.mem "button" data.explicit_roles)
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in
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(* Pop when element closes *)
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Ancestor_tracker.pop tracker
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]}
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*)
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(** {1 Types} *)
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(** Ancestor context containing element name and custom data. *)
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type 'data context = {
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name : string;
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(** Element name (lowercase). *)
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data : 'data;
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(** Checker-specific data. *)
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}
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(** Ancestor tracker state. *)
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type 'data t
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(** {1 Creation} *)
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val create : unit -> 'data t
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(** [create ()] creates a new empty ancestor tracker. *)
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val reset : 'data t -> unit
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(** [reset tracker] clears all ancestor contexts from the tracker. *)
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(** {1 Stack Operations} *)
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val push : 'data t -> string -> 'data -> unit
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(** [push tracker name data] pushes a new element context onto the stack.
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This should be called in [start_element] event handlers.
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@param tracker The ancestor tracker
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@param name The element name (will be lowercased)
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@param data Checker-specific data to associate with this element *)
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val pop : 'data t -> unit
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(** [pop tracker] pops the most recent element context from the stack.
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This should be called in [end_element] event handlers.
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@param tracker The ancestor tracker *)
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val peek : 'data t -> 'data context option
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(** [peek tracker] returns the most recent element context without removing it.
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@param tracker The ancestor tracker
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@return [Some context] if the stack is non-empty, [None] otherwise *)
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val depth : 'data t -> int
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(** [depth tracker] returns the current stack depth (number of ancestors).
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@param tracker The ancestor tracker
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@return The number of elements on the stack *)
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(** {1 Ancestor Queries} *)
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val has_ancestor : 'data t -> string -> bool
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(** [has_ancestor tracker name] checks if an element with the given name
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exists anywhere in the ancestor chain.
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@param tracker The ancestor tracker
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@param name The element name to search for (case-insensitive)
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@return [true] if an ancestor with this name exists *)
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val has_ancestor_with : 'data t -> (string -> 'data -> bool) -> bool
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(** [has_ancestor_with tracker predicate] checks if any ancestor satisfies
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the given predicate.
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@param tracker The ancestor tracker
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@param predicate Function that tests element name and data
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@return [true] if any ancestor satisfies the predicate *)
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val find_ancestor : 'data t -> string -> 'data context option
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(** [find_ancestor tracker name] finds the nearest ancestor with the given name.
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@param tracker The ancestor tracker
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@param name The element name to search for (case-insensitive)
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@return [Some context] for the nearest matching ancestor, [None] if not found *)
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val find_ancestor_with : 'data t -> (string -> 'data -> bool) -> 'data context option
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(** [find_ancestor_with tracker predicate] finds the nearest ancestor that
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satisfies the predicate.
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@param tracker The ancestor tracker
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@param predicate Function that tests element name and data
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@return [Some context] for the nearest matching ancestor, [None] if not found *)
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val get_all_ancestors : 'data t -> 'data context list
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(** [get_all_ancestors tracker] returns all ancestor contexts from nearest to root.
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@param tracker The ancestor tracker
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@return List of contexts, with the most recent first *)
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val filter_ancestors : 'data t -> (string -> 'data -> bool) -> 'data context list
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(** [filter_ancestors tracker predicate] returns all ancestors that satisfy
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the predicate.
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@param tracker The ancestor tracker
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@param predicate Function that tests element name and data
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@return List of matching contexts, from nearest to root *)
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val exists : 'data t -> (string -> 'data -> bool) -> bool
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(** [exists tracker predicate] checks if any ancestor satisfies the predicate.
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This is an alias for {!has_ancestor_with}.
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@param tracker The ancestor tracker
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@param predicate Function that tests element name and data
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@return [true] if any ancestor satisfies the predicate *)
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val for_all : 'data t -> (string -> 'data -> bool) -> bool
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(** [for_all tracker predicate] checks if all ancestors satisfy the predicate.
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@param tracker The ancestor tracker
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@param predicate Function that tests element name and data
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@return [true] if all ancestors satisfy the predicate (vacuously true for empty stack) *)
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val iter : 'data t -> (string -> 'data -> unit) -> unit
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(** [iter tracker f] applies function [f] to each ancestor from nearest to root.
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@param tracker The ancestor tracker
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@param f Function to apply to each ancestor *)
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val fold : 'data t -> ('acc -> string -> 'data -> 'acc) -> 'acc -> 'acc
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(** [fold tracker f init] folds over ancestors from nearest to root.
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@param tracker The ancestor tracker
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@param f Folding function
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@param init Initial accumulator value
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@return Final accumulator value *)
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(** {1 Parent Access} *)
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val get_parent : 'data t -> 'data context option
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(** [get_parent tracker] returns the immediate parent element context.
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This is equivalent to {!peek}.
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@param tracker The ancestor tracker
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@return [Some context] for the parent, [None] if at root *)
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val get_parent_name : 'data t -> string option
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(** [get_parent_name tracker] returns the immediate parent element name.
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@param tracker The ancestor tracker
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@return [Some name] for the parent, [None] if at root *)
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val get_parent_data : 'data t -> 'data option
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(** [get_parent_data tracker] returns the immediate parent's custom data.
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@param tracker The ancestor tracker
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@return [Some data] for the parent, [None] if at root *)
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(** {1 Multiple Ancestor Queries} *)
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val has_any_ancestor : 'data t -> string list -> bool
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(** [has_any_ancestor tracker names] checks if any of the given element names
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exists in the ancestor chain.
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@param tracker The ancestor tracker
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@param names List of element names to search for
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@return [true] if any name matches an ancestor *)
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val find_first_matching : 'data t -> string list -> (string * 'data context) option
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(** [find_first_matching tracker names] finds the nearest ancestor that matches
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any of the given names.
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@param tracker The ancestor tracker
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@param names List of element names to search for
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@return [Some (matched_name, context)] for the first match, [None] if no match *)
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(** {1 Stack Inspection} *)
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val is_empty : 'data t -> bool
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(** [is_empty tracker] checks if the stack is empty (at document root).
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@param tracker The ancestor tracker
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@return [true] if no elements are on the stack *)
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val to_list : 'data t -> 'data context list
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(** [to_list tracker] converts the stack to a list of contexts.
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This is an alias for {!get_all_ancestors}.
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@param tracker The ancestor tracker
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@return List of contexts from nearest to root *)
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val to_name_list : 'data t -> string list
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(** [to_name_list tracker] returns just the element names in the stack.
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@param tracker The ancestor tracker
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@return List of element names from nearest to root *)