#ifndef RUNTIME_PARSE_STACK_H_
#define RUNTIME_PARSE_STACK_H_

#ifdef __cplusplus
extern "C" {
#endif

#include "tree_sitter/parser.h"
#include "runtime/vector.h"

typedef struct Stack Stack;

typedef struct {
  TSTree *tree;
  TSStateId state;
} StackEntry;

typedef struct {
  TSTree **trees;
  size_t tree_count;
  int head_index;
} StackPopResult;

typedef struct {
  void *data;
  TSTree *(*callback)(void *data, TSTree *, TSTree *);
} TreeSelectionCallback;

/*
 *  Create a parse stack.
 */
Stack *ts_stack_new(TreeSelectionCallback);

/*
 *  Release any resources reserved by a parse stack.
 */
void ts_stack_delete(Stack *);

/*
 *  Get the stack's current number of heads.
 */
int ts_stack_head_count(const Stack *);

/*
 *  Get the state at given head of the stack. If the stack is empty, this
 *  returns the initial state (0).
 */
TSStateId ts_stack_top_state(const Stack *, int head);

/*
 *  Get the tree at given head of the stack. If the stack is empty, this
 *  returns NULL.
 */
TSTree *ts_stack_top_tree(const Stack *, int head);

/*
 *  Get the entry at the given head of the stack.
 */
StackEntry *ts_stack_head(Stack *, int head);

/*
 *  Get the number of successors for the parse stack entry.
 */
int ts_stack_entry_next_count(const StackEntry *);

/*
 *  Get the given successor for the parse stack entry.
 */
StackEntry *ts_stack_entry_next(const StackEntry *, int);

/*
 *  Push a (tree, state) pair onto the given head of the stack. Returns
 *  a boolean indicating whether the stack head was merged with an
 *  existing head.
 */
bool ts_stack_push(Stack *, int head, TSStateId, TSTree *);

/*
 *  Add an alternative tree for the given head of the stack.
 */
void ts_stack_add_alternative(Stack *, int head, TSTree *);

/*
 *  Pop the given number of entries from the given head of the stack. This
 *  operation can increase the number of stack heads by revealing multiple heads
 *  which had previously been merged. It returns a struct that indicates the
 *  index of each revealed head and the trees removed from that head.
 */
Vector ts_stack_pop(Stack *, int head, int count, bool count_extra);

/*
 *  Remove the given number of entries from the given head of the stack.
 */
void ts_stack_shrink(Stack *, int head, int count);

/*
 *  Split the given stack head into two heads, so that the stack can be
 *  transformed from its current state in multiple alternative ways. Returns
 *  the index of the newly-created head.
 */
int ts_stack_split(Stack *, int head);

/*
 *  Remove the given head from the stack.
 */
void ts_stack_remove_head(Stack *, int head);

/*
 *  Remove all entries from the stack.
 */
void ts_stack_clear(Stack *);

#ifdef __cplusplus
}
#endif

#endif  // RUNTIME_PARSE_STACK_H_