// NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE
//
// This is NOT the original regular expression code as written by Henry
// Spencer.  This code has been modified specifically for use with Vim, and
// should not be used apart from compiling Vim.  If you want a good regular
// expression library, get the original code.
//
// NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE

#ifndef NVIM_REGEXP_DEFS_H
#define NVIM_REGEXP_DEFS_H

#include <stdbool.h>

#include "nvim/pos.h"
#include "nvim/types.h"

/// Used for "magic_overruled".
typedef enum {
  OPTION_MAGIC_NOT_SET,  ///< p_magic not overruled
  OPTION_MAGIC_ON,       ///< magic on inside regexp
  OPTION_MAGIC_OFF,      ///< magic off inside regexp
} optmagic_T;

/// Magicness of a pattern, used by regexp code.
/// The order and values matter:
///  magic <= MAGIC_OFF includes MAGIC_NONE
///  magic >= MAGIC_ON  includes MAGIC_ALL
typedef enum {
  MAGIC_NONE = 1,  ///< "\V" very unmagic
  MAGIC_OFF = 2,   ///< "\M" or 'magic' off
  MAGIC_ON = 3,    ///< "\m" or 'magic'
  MAGIC_ALL = 4,   ///< "\v" very magic
} magic_T;

// The number of sub-matches is limited to 10.
// The first one (index 0) is the whole match, referenced with "\0".
// The second one (index 1) is the first sub-match, referenced with "\1".
// This goes up to the tenth (index 9), referenced with "\9".
#define NSUBEXP  10

// In the NFA engine: how many braces are allowed.
// TODO(RE): Use dynamic memory allocation instead of static, like here
#define NFA_MAX_BRACES 20

// In the NFA engine: how many states are allowed.
#define NFA_MAX_STATES 100000
#define NFA_TOO_EXPENSIVE (-1)

// Which regexp engine to use? Needed for vim_regcomp().
// Must match with 'regexpengine'.
#define AUTOMATIC_ENGINE    0
#define BACKTRACKING_ENGINE 1
#define NFA_ENGINE          2

typedef struct regengine regengine_T;
typedef struct regprog regprog_T;
typedef struct reg_extmatch reg_extmatch_T;

/// Structure to be used for multi-line matching.
/// Sub-match "no" starts in line "startpos[no].lnum" column "startpos[no].col"
/// and ends in line "endpos[no].lnum" just before column "endpos[no].col".
/// The line numbers are relative to the first line, thus startpos[0].lnum is
/// always 0.
/// When there is no match, the line number is -1.
typedef struct {
  regprog_T *regprog;
  lpos_T startpos[NSUBEXP];
  lpos_T endpos[NSUBEXP];

  colnr_T rmm_matchcol;  ///< match start without "\zs"
  int rmm_ic;
  colnr_T rmm_maxcol;  /// when not zero: maximum column
} regmmatch_T;

#include "nvim/buffer_defs.h"

// Structure returned by vim_regcomp() to pass on to vim_regexec().
// This is the general structure. For the actual matcher, two specific
// structures are used. See code below.
struct regprog {
  regengine_T *engine;
  unsigned regflags;
  unsigned re_engine;  ///< Automatic, backtracking or NFA engine.
  unsigned re_flags;   ///< Second argument for vim_regcomp().
  bool re_in_use;      ///< prog is being executed
};

// Structure used by the back track matcher.
// These fields are only to be used in regexp.c!
// See regexp.c for an explanation.
typedef struct {
  // These four members implement regprog_T.
  regengine_T *engine;
  unsigned regflags;
  unsigned re_engine;
  unsigned re_flags;
  bool re_in_use;

  int regstart;
  uint8_t reganch;
  uint8_t *regmust;
  int regmlen;
  uint8_t reghasz;
  uint8_t program[];
} bt_regprog_T;

// Structure representing a NFA state.
// An NFA state may have no outgoing edge, when it is a NFA_MATCH state.
typedef struct nfa_state nfa_state_T;
struct nfa_state {
  int c;
  nfa_state_T *out;
  nfa_state_T *out1;
  int id;
  int lastlist[2];                   // 0: normal, 1: recursive
  int val;
};

// Structure used by the NFA matcher.
typedef struct {
  // These four members implement regprog_T.
  regengine_T *engine;
  unsigned regflags;
  unsigned re_engine;
  unsigned re_flags;
  bool re_in_use;

  nfa_state_T *start;           // points into state[]

  int reganch;                          // pattern starts with ^
  int regstart;                         // char at start of pattern
  uint8_t *match_text;      // plain text to match with

  int has_zend;                         // pattern contains \ze
  int has_backref;                      // pattern contains \1 .. \9
  int reghasz;
  char *pattern;
  int nsubexp;                          // number of ()
  int nstate;
  nfa_state_T state[];
} nfa_regprog_T;

// Structure to be used for single-line matching.
// Sub-match "no" starts at "startp[no]" and ends just before "endp[no]".
// When there is no match, the pointer is NULL.
typedef struct {
  regprog_T *regprog;
  char *startp[NSUBEXP];
  char *endp[NSUBEXP];

  colnr_T rm_matchcol;  ///< match start without "\zs"
  bool rm_ic;
} regmatch_T;

// Structure used to store external references: "\z\(\)" to "\z\1".
// Use a reference count to avoid the need to copy this around.  When it goes
// from 1 to zero the matches need to be freed.
struct reg_extmatch {
  int16_t refcnt;
  uint8_t *matches[NSUBEXP];
};

struct regengine {
  /// bt_regcomp or nfa_regcomp
  regprog_T *(*regcomp)(uint8_t *, int);
  /// bt_regfree or nfa_regfree
  void (*regfree)(regprog_T *);
  /// bt_regexec_nl or nfa_regexec_nl
  int (*regexec_nl)(regmatch_T *, uint8_t *, colnr_T, bool);
  /// bt_regexec_mult or nfa_regexec_mult
  long (*regexec_multi)(regmmatch_T *, win_T *, buf_T *, linenr_T, colnr_T, proftime_T *, int *);
  // uint8_t *expr;
};

// Flags used by vim_regsub() and vim_regsub_both()
#define REGSUB_COPY      1
#define REGSUB_MAGIC     2
#define REGSUB_BACKSLASH 4

#endif  // NVIM_REGEXP_DEFS_H
