/* Header file for the tree-sitter integration.

Copyright (C) 2021 Free Software Foundation, Inc.

This file is part of GNU Emacs.

GNU Emacs is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or (at
your option) any later version.

GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */

#ifndef EMACS_TREE_SITTER_H
#define EMACS_TREE_SITTER_H

#include "lisp.h"

#include <tree_sitter/api.h>

INLINE_HEADER_BEGIN

/* A wrapper for a tree-sitter parser, but also contains a parse tree
   and other goodies for convenience.  */
struct Lisp_TS_Parser
{
  union vectorlike_header header;
  /* A symbol represents the language this parser uses.  It should be
   the symbol of the function provided by a language dynamic
   module.  */
  Lisp_Object language_symbol;
  Lisp_Object buffer;
  TSParser *parser;
  TSTree *tree;
  TSInput input;
  /* Re-parsing an unchanged buffer is not free for tree-sitter, so we
     only make it re-parse when need_reparse == true.  That usually
     means some change is made in the buffer.  But others could set
     this field to true to force tree-sitter to re-parse.  */
  bool need_reparse;
  /* These two positions record the buffer byte position (count from
     1) of the "visible region" that tree-sitter sees.  Unlike
     markers, These two positions do not change as the user inserts
     and deletes text around them. Before re-parse, we move these
     positions to match BUF_BEGV_BYTE and BUF_ZV_BYTE.  Note that we
     don't need to synchronize these positions when retrieving them in
     a function that involves a node: if the node is not outdated,
     these positions are synchronized.  */
  ptrdiff_t visible_beg;
  ptrdiff_t visible_end;
  /* This counter is incremented every time a change is made to the
     buffer in ts_record_change.  The node retrieved from this parser
     inherits this timestamp.  This way we can make sure the node is
     not outdated when we access its information.  */
  ptrdiff_t timestamp;
};

/* A wrapper around a tree-sitter node.  */
struct Lisp_TS_Node
{
  union vectorlike_header header;
  /* This prevents gc from collecting the tree before the node is done
     with it.  TSNode contains a pointer to the tree it belongs to,
     and the parser object, when collected by gc, will free that
     tree. */
  Lisp_Object parser;
  TSNode node;
  /* A node inherits its parser's timestamp at creation time.  The
     parser's timestamp increments as the buffer changes.  This way we
     can make sure the node is not outdated when we access its
     information.  */
  ptrdiff_t timestamp;
};

INLINE bool
TS_PARSERP (Lisp_Object x)
{
  return PSEUDOVECTORP (x, PVEC_TS_PARSER);
}

INLINE struct Lisp_TS_Parser *
XTS_PARSER (Lisp_Object a)
{
  eassert (TS_PARSERP (a));
  return XUNTAG (a, Lisp_Vectorlike, struct Lisp_TS_Parser);
}

INLINE bool
TS_NODEP (Lisp_Object x)
{
  return PSEUDOVECTORP (x, PVEC_TS_NODE);
}

INLINE struct Lisp_TS_Node *
XTS_NODE (Lisp_Object a)
{
  eassert (TS_NODEP (a));
  return XUNTAG (a, Lisp_Vectorlike, struct Lisp_TS_Node);
}

INLINE void
CHECK_TS_PARSER (Lisp_Object parser)
{
  CHECK_TYPE (TS_PARSERP (parser), Qtree_sitter_parser_p, parser);
}

INLINE void
CHECK_TS_NODE (Lisp_Object node)
{
  CHECK_TYPE (TS_NODEP (node), Qtree_sitter_node_p, node);
}

void
ts_record_change (ptrdiff_t start_byte, ptrdiff_t old_end_byte,
		  ptrdiff_t new_end_byte);

Lisp_Object
make_ts_parser (Lisp_Object buffer, TSParser *parser,
		TSTree *tree, Lisp_Object language_symbol);

Lisp_Object
make_ts_node (Lisp_Object parser, TSNode node);

extern void syms_of_tree_sitter (void);

INLINE_HEADER_END

#endif /* EMACS_TREE_SITTER_H */