/lpeg.c

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/*
** $Id: lptypes.h,v 1.8 2013/04/12 16:26:38 roberto Exp $
** LPeg - PEG pattern matching for Lua
** Copyright 2007, Lua.org & PUC-Rio  (see 'lpeg.html' for license)
** written by Roberto Ierusalimschy
*/

#if !defined(lptypes_h)
#define lptypes_h


#if !defined(LPEG_DEBUG)
#define NDEBUG
#endif

#include <assert.h>
#include <limits.h>

#include "lua.h"


#define VERSION         "0.12"


#define PATTERN_T	"lpeg-pattern"
#define MAXSTACKIDX	"lpeg-maxstack"


/*
** compatibility with Lua 5.2
*/
#if (LUA_VERSION_NUM == 502)

#undef lua_equal
#define lua_equal(L,idx1,idx2)  lua_compare(L,(idx1),(idx2),LUA_OPEQ)

#undef lua_getfenv
#define lua_getfenv	lua_getuservalue
#undef lua_setfenv
#define lua_setfenv	lua_setuservalue

#undef lua_objlen
#define lua_objlen	lua_rawlen

#undef luaL_register
#define luaL_register(L,n,f) \
	{ if ((n) == NULL) luaL_setfuncs(L,f,0); else luaL_newlib(L,f); }

#endif


/* default maximum size for call/backtrack stack */
#if !defined(MAXBACK)
#define MAXBACK         100
#endif


/* maximum number of rules in a grammar */
#define MAXRULES        200



/* initial size for capture's list */
#define INITCAPSIZE	32


/* index, on Lua stack, for subject */
#define SUBJIDX		2

/* number of fixed arguments to 'match' (before capture arguments) */
#define FIXEDARGS	3

/* index, on Lua stack, for capture list */
#define caplistidx(ptop)	((ptop) + 2)

/* index, on Lua stack, for pattern's ktable */
#define ktableidx(ptop)		((ptop) + 3)

/* index, on Lua stack, for backtracking stack */
#define stackidx(ptop)	((ptop) + 4)



typedef unsigned char byte;


#define BITSPERCHAR		8

#define CHARSETSIZE		((UCHAR_MAX/BITSPERCHAR) + 1)



typedef struct Charset {
  byte cs[CHARSETSIZE];
} Charset;



#define loopset(v,b)    { int v; for (v = 0; v < CHARSETSIZE; v++) {b;} }

/* access to charset */
#define treebuffer(t)      ((byte *)((t) + 1))

/* number of slots needed for 'n' bytes */
#define bytes2slots(n)  (((n) - 1) / sizeof(TTree) + 1)

/* set 'b' bit in charset 'cs' */
#define setchar(cs,b)   ((cs)[(b) >> 3] |= (1 << ((b) & 7)))


/*
** in capture instructions, 'kind' of capture and its offset are
** packed in field 'aux', 4 bits for each
*/
#define getkind(op)		((op)->i.aux & 0xF)
#define getoff(op)		(((op)->i.aux >> 4) & 0xF)
#define joinkindoff(k,o)	((k) | ((o) << 4))

#define MAXOFF		0xF
#define MAXAUX		0xFF


/* maximum number of bytes to look behind */
#define MAXBEHIND	MAXAUX


/* maximum size (in elements) for a pattern */
#define MAXPATTSIZE	(SHRT_MAX - 10)


/* size (in elements) for an instruction plus extra l bytes */
#define instsize(l)  (((l) + sizeof(Instruction) - 1)/sizeof(Instruction) + 1)


/* size (in elements) for a ISet instruction */
#define CHARSETINSTSIZE		instsize(CHARSETSIZE)

/* size (in elements) for a IFunc instruction */
#define funcinstsize(p)		((p)->i.aux + 2)



#define testchar(st,c)	(((int)(st)[((c) >> 3)] & (1 << ((c) & 7))))


#endif

/*
** $Id: lptree.h,v 1.2 2013/03/24 13:51:12 roberto Exp $
*/

#if !defined(lptree_h)
#define lptree_h




/*
** types of trees
*/
typedef enum TTag {
  TChar = 0, TSet, TAny,  /* standard PEG elements */
  TTrue, TFalse,
  TRep,
  TSeq, TChoice,
  TNot, TAnd,
  TCall,
  TOpenCall,
  TRule,  /* sib1 is rule's pattern, sib2 is 'next' rule */
  TGrammar,  /* sib1 is initial (and first) rule */
  TBehind,  /* match behind */
  TCapture,  /* regular capture */
  TRunTime  /* run-time capture */
} TTag;

/* number of siblings for each tree */
extern const byte numsiblings[];


/*
** Tree trees
** The first sibling of a tree (if there is one) is immediately after
** the tree.  A reference to a second sibling (ps) is its position
** relative to the position of the tree itself.  A key in ktable
** uses the (unique) address of the original tree that created that
** entry. NULL means no data.
*/
typedef struct TTree {
  byte tag;
  byte cap;  /* kind of capture (if it is a capture) */
  unsigned short key;  /* key in ktable for Lua data (0 if no key) */
  union {
    int ps;  /* occasional second sibling */
    int n;  /* occasional counter */
  } u;
} TTree;


/*
** A complete pattern has its tree plus, if already compiled,
** its corresponding code
*/
typedef struct Pattern {
  union Instruction *code;
  int codesize;
  TTree tree[1];
} Pattern;


/* number of siblings for each tree */
extern const byte numsiblings[];

/* access to siblings */
#define sib1(t)         ((t) + 1)
#define sib2(t)         ((t) + (t)->u.ps)






#endif

/*
** $Id: lpcap.h,v 1.1 2013/03/21 20:25:12 roberto Exp $
*/

#if !defined(lpcap_h)
#define lpcap_h




/* kinds of captures */
typedef enum CapKind {
  Cclose, Cposition, Cconst, Cbackref, Carg, Csimple, Ctable, Cfunction,
  Cquery, Cstring, Cnum, Csubst, Cfold, Cruntime, Cgroup
} CapKind;


typedef struct Capture {
  const char *s;  /* subject position */
  short idx;  /* extra info about capture (group name, arg index, etc.) */
  byte kind;  /* kind of capture */
  byte siz;  /* size of full capture + 1 (0 = not a full capture) */
} Capture;


typedef struct CapState {
  Capture *cap;  /* current capture */
  Capture *ocap;  /* (original) capture list */
  lua_State *L;
  int ptop;  /* index of last argument to 'match' */
  const char *s;  /* original string */
  int valuecached;  /* value stored in cache slot */
} CapState;


int runtimecap (CapState *cs, Capture *close, const char *s, int *rem);
int getcaptures (lua_State *L, const char *s, const char *r, int ptop);
int finddyncap (Capture *cap, Capture *last);

#endif


/*
** $Id: lpvm.h,v 1.2 2013/04/03 20:37:18 roberto Exp $
*/

#if !defined(lpvm_h)
#define lpvm_h



/* Virtual Machine's instructions */
typedef enum Opcode {
  IAny, /* if no char, fail */
  IChar,  /* if char != aux, fail */
  ISet,  /* if char not in buff, fail */
  ITestAny,  /* in no char, jump to 'offset' */
  ITestChar,  /* if char != aux, jump to 'offset' */
  ITestSet,  /* if char not in buff, jump to 'offset' */
  ISpan,  /* read a span of chars in buff */
  IBehind,  /* walk back 'aux' characters (fail if not possible) */
  IRet,  /* return from a rule */
  IEnd,  /* end of pattern */
  IChoice,  /* stack a choice; next fail will jump to 'offset' */
  IJmp,  /* jump to 'offset' */
  ICall,  /* call rule at 'offset' */
  IOpenCall,  /* call rule number 'key' (must be closed to a ICall) */
  ICommit,  /* pop choice and jump to 'offset' */
  IPartialCommit,  /* update top choice to current position and jump */
  IBackCommit,  /* "fails" but jump to its own 'offset' */
  IFailTwice,  /* pop one choice and then fail */
  IFail,  /* go back to saved state on choice and jump to saved offset */
  IGiveup,  /* internal use */
  IFullCapture,  /* complete capture of last 'off' chars */
  IOpenCapture,  /* start a capture */
  ICloseCapture,
  ICloseRunTime
} Opcode;



typedef union Instruction {
  struct Inst {
    byte code;
    byte aux;
    short key;
  } i;
  int offset;
  byte buff[1];
} Instruction;


int getposition (lua_State *L, int t, int i);
void printpatt (Instruction *p, int n);
const char *match (lua_State *L, const char *o, const char *s, const char *e,
                   Instruction *op, Capture *capture, int ptop);
int verify (lua_State *L, Instruction *op, const Instruction *p,
            Instruction *e, int postable, int rule);
void checkrule (lua_State *L, Instruction *op, int from, int to,
                int postable, int rule);


#endif

/*
** $Id: lpcode.h,v 1.5 2013/04/04 21:24:45 roberto Exp $
*/

#if !defined(lpcode_h)
#define lpcode_h

#include "lua.h"


int tocharset (TTree *tree, Charset *cs);
int checkaux (TTree *tree, int pred);
int fixedlenx (TTree *tree, int count, int len);
int hascaptures (TTree *tree);
int lp_gc (lua_State *L);
Instruction *compile (lua_State *L, Pattern *p);
void reallocprog (lua_State *L, Pattern *p, int nsize);
int sizei (const Instruction *i);


#define PEnullable      0
#define PEnofail        1

#define nofail(t)	checkaux(t, PEnofail)
#define nullable(t)	checkaux(t, PEnullable)

#define fixedlen(t)     fixedlenx(t, 0, 0)



#endif
/*
** $Id: lpprint.h,v 1.1 2013/03/21 20:25:12 roberto Exp $
*/


#if !defined(lpprint_h)
#define lpprint_h




#if defined(LPEG_DEBUG)

void printpatt (Instruction *p, int n);
void printtree (TTree *tree, int ident);
void printktable (lua_State *L, int idx);
void printcharset (const byte *st);
void printcaplist (Capture *cap, Capture *limit);

#else

#define printktable(L,idx)  \
	luaL_error(L, "function only implemented in debug mode")
#define printtree(tree,i)  \
	luaL_error(L, "function only implemented in debug mode")
#define printpatt(p,n)  \
	luaL_error(L, "function only implemented in debug mode")

#endif


#endif

/*
** $Id: lpcap.c,v 1.4 2013/03/21 20:25:12 roberto Exp $
** Copyright 2007, Lua.org & PUC-Rio  (see 'lpeg.html' for license)
*/

#include "lua.h"
#include "lauxlib.h"



#define captype(cap)	((cap)->kind)

#define isclosecap(cap)	(captype(cap) == Cclose)

#define closeaddr(c)	((c)->s + (c)->siz - 1)

#define isfullcap(cap)	((cap)->siz != 0)

#define getfromktable(cs,v)	lua_rawgeti((cs)->L, ktableidx((cs)->ptop), v)

#define pushluaval(cs)		getfromktable(cs, (cs)->cap->idx)



/*
** Put at the cache for Lua values the value indexed by 'v' in ktable
** of the running pattern (if it is not there yet); returns its index.
*/
static int updatecache (CapState *cs, int v) {
  int idx = cs->ptop + 1;  /* stack index of cache for Lua values */
  if (v != cs->valuecached) {  /* not there? */
    getfromktable(cs, v);  /* get value from 'ktable' */
    lua_replace(cs->L, idx);  /* put it at reserved stack position */
    cs->valuecached = v;  /* keep track of what is there */
  }
  return idx;
}


static int pushcapture (CapState *cs);


/*
** Goes back in a list of captures looking for an open capture
** corresponding to a close
*/
static Capture *findopen (Capture *cap) {
  int n = 0;  /* number of closes waiting an open */
  for (;;) {
    cap--;
    if (isclosecap(cap)) n++;  /* one more open to skip */
    else if (!isfullcap(cap))
      if (n-- == 0) return cap;
  }
}


/*
** Go to the next capture
*/
static void nextcap (CapState *cs) {
  Capture *cap = cs->cap;
  if (!isfullcap(cap)) {  /* not a single capture? */
    int n = 0;  /* number of opens waiting a close */
    for (;;) {  /* look for corresponding close */
      cap++;
      if (isclosecap(cap)) {
        if (n-- == 0) break;
      }
      else if (!isfullcap(cap)) n++;
    }
  }
  cs->cap = cap + 1;  /* + 1 to skip last close (or entire single capture) */
}


/*
** Push on the Lua stack all values generated by nested captures inside
** the current capture. Returns number of values pushed. 'addextra'
** makes it push the entire match after all captured values. The
** entire match is pushed also if there are no other nested values,
** so the function never returns zero.
*/
static int pushnestedvalues (CapState *cs, int addextra) {
  Capture *co = cs->cap;
  if (isfullcap(cs->cap++)) {  /* no nested captures? */
    lua_pushlstring(cs->L, co->s, co->siz - 1);  /* push whole match */
    return 1;  /* that is it */
  }
  else {
    int n = 0;
    while (!isclosecap(cs->cap))  /* repeat for all nested patterns */
      n += pushcapture(cs);
    if (addextra || n == 0) {  /* need extra? */
      lua_pushlstring(cs->L, co->s, cs->cap->s - co->s);  /* push whole match */
      n++;
    }
    cs->cap++;  /* skip close entry */
    return n;
  }
}


/*
** Push only the first value generated by nested captures
*/
static void pushonenestedvalue (CapState *cs) {
  int n = pushnestedvalues(cs, 0);
  if (n > 1)
    lua_pop(cs->L, n - 1);  /* pop extra values */
}


/*
** Try to find a named group capture with the name given at the top of
** the stack; goes backward from 'cap'.
*/
static Capture *findback (CapState *cs, Capture *cap) {
  lua_State *L = cs->L;
  while (cap-- > cs->ocap) {  /* repeat until end of list */
    if (isclosecap(cap))
      cap = findopen(cap);  /* skip nested captures */
    else if (!isfullcap(cap))
      continue; /* opening an enclosing capture: skip and get previous */
    if (captype(cap) == Cgroup) {
      getfromktable(cs, cap->idx);  /* get group name */
      if (lua_equal(L, -2, -1)) {  /* right group? */
        lua_pop(L, 2);  /* remove reference name and group name */
        return cap;
      }
      else lua_pop(L, 1);  /* remove group name */
    }
  }
  luaL_error(L, "back reference '%s' not found", lua_tostring(L, -1));
  return NULL;  /* to avoid warnings */
}


/*
** Back-reference capture. Return number of values pushed.
*/
static int backrefcap (CapState *cs) {
  int n;
  Capture *curr = cs->cap;
  pushluaval(cs);  /* reference name */
  cs->cap = findback(cs, curr);  /* find corresponding group */
  n = pushnestedvalues(cs, 0);  /* push group's values */
  cs->cap = curr + 1;
  return n;
}


/*
** Table capture: creates a new table and populates it with nested
** captures.
*/
static int tablecap (CapState *cs) {
  lua_State *L = cs->L;
  int n = 0;
  lua_newtable(L);
  if (isfullcap(cs->cap++))
    return 1;  /* table is empty */
  while (!isclosecap(cs->cap)) {
    if (captype(cs->cap) == Cgroup && cs->cap->idx != 0) {  /* named group? */
      pushluaval(cs);  /* push group name */
      pushonenestedvalue(cs);
      lua_settable(L, -3);
    }
    else {  /* not a named group */
      int i;
      int k = pushcapture(cs);
      for (i = k; i > 0; i--)  /* store all values into table */
        lua_rawseti(L, -(i + 1), n + i);
      n += k;
    }
  }
  cs->cap++;  /* skip close entry */
  return 1;  /* number of values pushed (only the table) */
}


/*
** Table-query capture
*/
static int querycap (CapState *cs) {
  int idx = cs->cap->idx;
  pushonenestedvalue(cs);  /* get nested capture */
  lua_gettable(cs->L, updatecache(cs, idx));  /* query cap. value at table */
  if (!lua_isnil(cs->L, -1))
    return 1;
  else {  /* no value */
    lua_pop(cs->L, 1);  /* remove nil */
    return 0;
  }
}


/*
** Fold capture
*/
static int foldcap (CapState *cs) {
  int n;
  lua_State *L = cs->L;
  int idx = cs->cap->idx;
  if (isfullcap(cs->cap++) ||  /* no nested captures? */
      isclosecap(cs->cap) ||  /* no nested captures (large subject)? */
      (n = pushcapture(cs)) == 0)  /* nested captures with no values? */
    return luaL_error(L, "no initial value for fold capture");
  if (n > 1)
    lua_pop(L, n - 1);  /* leave only one result for accumulator */
  while (!isclosecap(cs->cap)) {
    lua_pushvalue(L, updatecache(cs, idx));  /* get folding function */
    lua_insert(L, -2);  /* put it before accumulator */
    n = pushcapture(cs);  /* get next capture's values */
    lua_call(L, n + 1, 1);  /* call folding function */
  }
  cs->cap++;  /* skip close entry */
  return 1;  /* only accumulator left on the stack */
}


/*
** Function capture
*/
static int functioncap (CapState *cs) {
  int n;
  int top = lua_gettop(cs->L);
  pushluaval(cs);  /* push function */
  n = pushnestedvalues(cs, 0);  /* push nested captures */
  lua_call(cs->L, n, LUA_MULTRET);  /* call function */
  return lua_gettop(cs->L) - top;  /* return function's results */
}


/*
** Select capture
*/
static int numcap (CapState *cs) {
  int idx = cs->cap->idx;  /* value to select */
  if (idx == 0) {  /* no values? */
    nextcap(cs);  /* skip entire capture */
    return 0;  /* no value produced */
  }
  else {
    int n = pushnestedvalues(cs, 0);
    if (n < idx)  /* invalid index? */
      return luaL_error(cs->L, "no capture '%d'", idx);
    else {
      lua_pushvalue(cs->L, -(n - idx + 1));  /* get selected capture */
      lua_replace(cs->L, -(n + 1));  /* put it in place of 1st capture */
      lua_pop(cs->L, n - 1);  /* remove other captures */
      return 1;
    }
  }
}


/*
** Return the stack index of the first runtime capture in the given
** list of captures (or zero if no runtime captures)
*/
int finddyncap (Capture *cap, Capture *last) {
  for (; cap < last; cap++) {
    if (cap->kind == Cruntime)
      return cap->idx;  /* stack position of first capture */
  }
  return 0;  /* no dynamic captures in this segment */
}


/*
** Calls a runtime capture. Returns number of captures removed by
** the call, including the initial Cgroup. (Captures to be added are
** on the Lua stack.)
*/
int runtimecap (CapState *cs, Capture *close, const char *s, int *rem) {
  int n, id;
  lua_State *L = cs->L;
  int otop = lua_gettop(L);
  Capture *open = findopen(close);
  assert(captype(open) == Cgroup);
  id = finddyncap(open, close);  /* get first dynamic capture argument */
  close->kind = Cclose;  /* closes the group */
  close->s = s;
  cs->cap = open; cs->valuecached = 0;  /* prepare capture state */
  luaL_checkstack(L, 4, "too many runtime captures");
  pushluaval(cs);  /* push function to be called */
  lua_pushvalue(L, SUBJIDX);  /* push original subject */
  lua_pushinteger(L, s - cs->s + 1);  /* push current position */
  n = pushnestedvalues(cs, 0);  /* push nested captures */
  lua_call(L, n + 2, LUA_MULTRET);  /* call dynamic function */
  if (id > 0) {  /* are there old dynamic captures to be removed? */
    int i;
    for (i = id; i <= otop; i++)
      lua_remove(L, id);  /* remove old dynamic captures */
    *rem = otop - id + 1;  /* total number of dynamic captures removed */
  }
  else
    *rem = 0;  /* no dynamic captures removed */
  return close - open;  /* number of captures of all kinds removed */
}


/*
** Auxiliary structure for substitution and string captures: keep
** information about nested captures for future use, avoiding to push
** string results into Lua
*/
typedef struct StrAux {
  int isstring;  /* whether capture is a string */
  union {
    Capture *cp;  /* if not a string, respective capture */
    struct {  /* if it is a string... */
      const char *s;  /* ... starts here */
      const char *e;  /* ... ends here */
    } s;
  } u;
} StrAux;

#define MAXSTRCAPS	10

/*
** Collect values from current capture into array 'cps'. Current
** capture must be Cstring (first call) or Csimple (recursive calls).
** (In first call, fills %0 with whole match for Cstring.)
** Returns number of elements in the array that were filled.
*/
static int getstrcaps (CapState *cs, StrAux *cps, int n) {
  int k = n++;
  cps[k].isstring = 1;  /* get string value */
  cps[k].u.s.s = cs->cap->s;  /* starts here */
  if (!isfullcap(cs->cap++)) {  /* nested captures? */
    while (!isclosecap(cs->cap)) {  /* traverse them */
      if (n >= MAXSTRCAPS)  /* too many captures? */
        nextcap(cs);  /* skip extra captures (will not need them) */
      else if (captype(cs->cap) == Csimple)  /* string? */
        n = getstrcaps(cs, cps, n);  /* put info. into array */
      else {
        cps[n].isstring = 0;  /* not a string */
        cps[n].u.cp = cs->cap;  /* keep original capture */
        nextcap(cs);
        n++;
      }
    }
    cs->cap++;  /* skip close */
  }
  cps[k].u.s.e = closeaddr(cs->cap - 1);  /* ends here */
  return n;
}


/*
** add next capture value (which should be a string) to buffer 'b'
*/
static int addonestring (luaL_Buffer *b, CapState *cs, const char *what);


/*
** String capture: add result to buffer 'b' (instead of pushing
** it into the stack)
*/
static void stringcap (luaL_Buffer *b, CapState *cs) {
  StrAux cps[MAXSTRCAPS];
  int n;
  size_t len, i;
  const char *fmt;  /* format string */
  fmt = lua_tolstring(cs->L, updatecache(cs, cs->cap->idx), &len);
  n = getstrcaps(cs, cps, 0) - 1;  /* collect nested captures */
  for (i = 0; i < len; i++) {  /* traverse them */
    if (fmt[i] != '%')  /* not an escape? */
      luaL_addchar(b, fmt[i]);  /* add it to buffer */
    else if (fmt[++i] < '0' || fmt[i] > '9')  /* not followed by a digit? */
      luaL_addchar(b, fmt[i]);  /* add to buffer */
    else {
      int l = fmt[i] - '0';  /* capture index */
      if (l > n)
        luaL_error(cs->L, "invalid capture index (%d)", l);
      else if (cps[l].isstring)
        luaL_addlstring(b, cps[l].u.s.s, cps[l].u.s.e - cps[l].u.s.s);
      else {
        Capture *curr = cs->cap;
        cs->cap = cps[l].u.cp;  /* go back to evaluate that nested capture */
        if (!addonestring(b, cs, "capture"))
          luaL_error(cs->L, "no values in capture index %d", l);
        cs->cap = curr;  /* continue from where it stopped */
      }
    }
  }
}


/*
** Substitution capture: add result to buffer 'b'
*/
static void substcap (luaL_Buffer *b, CapState *cs) {
  const char *curr = cs->cap->s;
  if (isfullcap(cs->cap))  /* no nested captures? */
    luaL_addlstring(b, curr, cs->cap->siz - 1);  /* keep original text */
  else {
    cs->cap++;  /* skip open entry */
    while (!isclosecap(cs->cap)) {  /* traverse nested captures */
      const char *next = cs->cap->s;
      luaL_addlstring(b, curr, next - curr);  /* add text up to capture */
      if (addonestring(b, cs, "replacement"))
        curr = closeaddr(cs->cap - 1);  /* continue after match */
      else  /* no capture value */
        curr = next;  /* keep original text in final result */
    }
    luaL_addlstring(b, curr, cs->cap->s - curr);  /* add last piece of text */
  }
  cs->cap++;  /* go to next capture */
}


/*
** Evaluates a capture and adds its first value to buffer 'b'; returns
** whether there was a value
*/
static int addonestring (luaL_Buffer *b, CapState *cs, const char *what) {
  switch (captype(cs->cap)) {
    case Cstring:
      stringcap(b, cs);  /* add capture directly to buffer */
      return 1;
    case Csubst:
      substcap(b, cs);  /* add capture directly to buffer */
      return 1;
    default: {
      lua_State *L = cs->L;
      int n = pushcapture(cs);
      if (n > 0) {
        if (n > 1) lua_pop(L, n - 1);  /* only one result */
        if (!lua_isstring(L, -1))
          luaL_error(L, "invalid %s value (a %s)", what, luaL_typename(L, -1));
        luaL_addvalue(b);
      }
      return n;
    }
  }
}


/*
** Push all values of the current capture into the stack; returns
** number of values pushed
*/
static int pushcapture (CapState *cs) {
  lua_State *L = cs->L;
  luaL_checkstack(L, 4, "too many captures");
  switch (captype(cs->cap)) {
    case Cposition: {
      lua_pushinteger(L, cs->cap->s - cs->s + 1);
      cs->cap++;
      return 1;
    }
    case Cconst: {
      pushluaval(cs);
      cs->cap++;
      return 1;
    }
    case Carg: {
      int arg = (cs->cap++)->idx;
      if (arg + FIXEDARGS > cs->ptop)
        return luaL_error(L, "reference to absent argument #%d", arg);
      lua_pushvalue(L, arg + FIXEDARGS);
      return 1;
    }
    case Csimple: {
      int k = pushnestedvalues(cs, 1);
      lua_insert(L, -k);  /* make whole match be first result */
      return k;
    }
    case Cruntime: {
      lua_pushvalue(L, (cs->cap++)->idx);  /* value is in the stack */
      return 1;
    }
    case Cstring: {
      luaL_Buffer b;
      luaL_buffinit(L, &b);
      stringcap(&b, cs);
      luaL_pushresult(&b);
      return 1;
    }
    case Csubst: {
      luaL_Buffer b;
      luaL_buffinit(L, &b);
      substcap(&b, cs);
      luaL_pushresult(&b);
      return 1;
    }
    case Cgroup: {
      if (cs->cap->idx == 0)  /* anonymous group? */
        return pushnestedvalues(cs, 0);  /* add all nested values */
      else {  /* named group: add no values */
        nextcap(cs);  /* skip capture */
        return 0;
      }
    }
    case Cbackref: return backrefcap(cs);
    case Ctable: return tablecap(cs);
    case Cfunction: return functioncap(cs);
    case Cnum: return numcap(cs);
    case Cquery: return querycap(cs);
    case Cfold: return foldcap(cs);
    default: assert(0); return 0;
  }
}


/*
** Prepare a CapState structure and traverse the entire list of
** captures in the stack pushing its results. 's' is the subject
** string, 'r' is the final position of the match, and 'ptop'
** the index in the stack where some useful values were pushed.
** Returns the number of results pushed. (If the list produces no
** results, push the final position of the match.)
*/
int getcaptures (lua_State *L, const char *s, const char *r, int ptop) {
  Capture *capture = (Capture *)lua_touserdata(L, caplistidx(ptop));
  int n = 0;
  if (!isclosecap(capture)) {  /* is there any capture? */
    CapState cs;
    cs.ocap = cs.cap = capture; cs.L = L;
    cs.s = s; cs.valuecached = 0; cs.ptop = ptop;
    do {  /* collect their values */
      n += pushcapture(&cs);
    } while (!isclosecap(cs.cap));
  }
  if (n == 0) {  /* no capture values? */
    lua_pushinteger(L, r - s + 1);  /* return only end position */
    n = 1;
  }
  return n;
}


/*
** $Id: lpcode.c,v 1.18 2013/04/12 16:30:33 roberto Exp $
** Copyright 2007, Lua.org & PUC-Rio  (see 'lpeg.html' for license)
*/

#include <limits.h>


#include "lua.h"
#include "lauxlib.h"



/* signals a "no-instruction */
#define NOINST		-1



static const Charset fullset_ =
  {{0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF}};

static const Charset *fullset = &fullset_;

/*
** {======================================================
** Analysis and some optimizations
** =======================================================
*/

/*
** Check whether a charset is empty (IFail), singleton (IChar),
** full (IAny), or none of those (ISet).
*/
static Opcode charsettype (const byte *cs, int *c) {
  int count = 0;
  int i;
  int candidate = -1;  /* candidate position for a char */
  for (i = 0; i < CHARSETSIZE; i++) {
    int b = cs[i];
    if (b == 0) {
      if (count > 1) return ISet;  /* else set is still empty */
    }
    else if (b == 0xFF) {
      if (count < (i * BITSPERCHAR))
        return ISet;
      else count += BITSPERCHAR;  /* set is still full */
    }
    else if ((b & (b - 1)) == 0) {  /* byte has only one bit? */
      if (count > 0)
        return ISet;  /* set is neither full nor empty */
      else {  /* set has only one char till now; track it */
        count++;
        candidate = i;
      }
    }
    else return ISet;  /* byte is neither empty, full, nor singleton */
  }
  switch (count) {
    case 0: return IFail;  /* empty set */
    case 1: {  /* singleton; find character bit inside byte */
      int b = cs[candidate];
      *c = candidate * BITSPERCHAR;
      if ((b & 0xF0) != 0) { *c += 4; b >>= 4; }
      if ((b & 0x0C) != 0) { *c += 2; b >>= 2; }
      if ((b & 0x02) != 0) { *c += 1; }
      return IChar;
    }
    default: {
       assert(count == CHARSETSIZE * BITSPERCHAR);  /* full set */
       return IAny;
    }
  }
}

/*
** A few basic operations on Charsets
*/
static void cs_complement (Charset *cs) {
  loopset(i, cs->cs[i] = ~cs->cs[i]);
}


static int cs_equal (const byte *cs1, const byte *cs2) {
  loopset(i, if (cs1[i] != cs2[i]) return 0);
  return 1;
}


/*
** computes whether sets cs1 and cs2 are disjoint
*/
static int cs_disjoint (const Charset *cs1, const Charset *cs2) {
  loopset(i, if ((cs1->cs[i] & cs2->cs[i]) != 0) return 0;)
  return 1;
}


/*
** Convert a 'char' pattern (TSet, TChar, TAny) to a charset
*/
int tocharset (TTree *tree, Charset *cs) {
  switch (tree->tag) {
    case TSet: {  /* copy set */
      loopset(i, cs->cs[i] = treebuffer(tree)[i]);
      return 1;
    }
    case TChar: {  /* only one char */
      assert(0 <= tree->u.n && tree->u.n <= UCHAR_MAX);
      loopset(i, cs->cs[i] = 0);  /* erase all chars */
      setchar(cs->cs, tree->u.n);  /* add that one */
      return 1;
    }
    case TAny: {
      loopset(i, cs->cs[i] = 0xFF);  /* add all to the set */
      return 1;
    }
    default: return 0;
  }
}


/*
** Checks whether a pattern has captures
*/
int hascaptures (TTree *tree) {
 tailcall:
  switch (tree->tag) {
    case TCapture: case TRunTime:
      return 1;
    default: {
      switch (numsiblings[tree->tag]) {
        case 1:  /* return hascaptures(sib1(tree)); */
          tree = sib1(tree); goto tailcall;
        case 2:
          if (hascaptures(sib1(tree))) return 1;
          /* else return hascaptures(sib2(tree)); */
          tree = sib2(tree); goto tailcall;
        default: assert(numsiblings[tree->tag] == 0); return 0;
      }
    }
  }
}


/*
** Checks how a pattern behaves regarding the empty string,
** in one of two different ways:
** A pattern is *nullable* if it can match without consuming any character;
** A pattern is *nofail* if it never fails for any string
** (including the empty string).
** The difference is only for predicates and run-time captures;
** for other patterns, the two properties are equivalent.
** (With predicates, &'a' is nullable but not nofail. Of course,
** nofail => nullable.)
** These functions are all convervative in the following way:
**    p is nullable => nullable(p)
**    nofail(p) => p cannot fail
** The function assumes that TOpenCall is not nullable;
** this will be checked again when the grammar is fixed.)
** Run-time captures can do whatever they want, so the result
** is conservative.
*/
int checkaux (TTree *tree, int pred) {
 tailcall:
  switch (tree->tag) {
    case TChar: case TSet: case TAny:
    case TFalse: case TOpenCall:
      return 0;  /* not nullable */
    case TRep: case TTrue:
      return 1;  /* no fail */
    case TNot: case TBehind:  /* can match empty, but can fail */
      if (pred == PEnofail) return 0;
      else return 1;  /* PEnullable */
    case TAnd:  /* can match empty; fail iff body does */
      if (pred == PEnullable) return 1;
      /* else return checkaux(sib1(tree), pred); */
      tree = sib1(tree); goto tailcall;
    case TRunTime:  /* can fail; match empty iff body does */
      if (pred == PEnofail) return 0;
      /* else return checkaux(sib1(tree), pred); */
      tree = sib1(tree); goto tailcall;
    case TSeq:
      if (!checkaux(sib1(tree), pred)) return 0;
      /* else return checkaux(sib2(tree), pred); */
      tree = sib2(tree); goto tailcall;
    case TChoice:
      if (checkaux(sib2(tree), pred)) return 1;
      /* else return checkaux(sib1(tree), pred); */
      tree = sib1(tree); goto tailcall;
    case TCapture: case TGrammar: case TRule:
      /* return checkaux(sib1(tree), pred); */
      tree = sib1(tree); goto tailcall;
    case TCall:  /* return checkaux(sib2(tree), pred); */
      tree = sib2(tree); goto tailcall;
    default: assert(0); return 0;
  };
}


/*
** number of characters to match a pattern (or -1 if variable)
** ('count' avoids infinite loops for grammars)
*/
int fixedlenx (TTree *tree, int count, int len) {
 tailcall:
  switch (tree->tag) {
    case TChar: case TSet: case TAny:
      return len + 1;
    case TFalse: case TTrue: case TNot: case TAnd: case TBehind:
      return len;
    case TRep: case TRunTime: case TOpenCall:
      return -1;
    case TCapture: case TRule: case TGrammar:
      /* return fixedlenx(sib1(tree), count); */
      tree = sib1(tree); goto tailcall;
    case TCall:
      if (count++ >= MAXRULES)
        return -1;  /* may be a loop */
      /* else return fixedlenx(sib2(tree), count); */
      tree = sib2(tree); goto tailcall;
    case TSeq: {
      len = fixedlenx(sib1(tree), count, len);
      if (len < 0) return -1;
      /* else return fixedlenx(sib2(tree), count, len); */
      tree = sib2(tree); goto tailcall;
    }
    case TChoice: {
      int n1, n2;
      n1 = fixedlenx(sib1(tree), count, len);
      if (n1 < 0) return -1;
      n2 = fixedlenx(sib2(tree), count, len);
      if (n1 == n2) return n1;
      else return -1;
    }
    default: assert(0); return 0;
  };
}


/*
** Computes the 'first set' of a pattern.
** The result is a conservative aproximation:
**   match p ax -> x' for some x ==> a in first(p).
** The set 'follow' is the first set of what follows the
** pattern (full set if nothing follows it).
** The function returns 0 when this set can be used for
** tests that avoid the pattern altogether.
** A non-zero return can happen for two reasons:
** 1) match p '' -> ''            ==> returns 1.
** (tests cannot be used because they always fail for an empty input)
** 2) there is a match-time capture ==> returns 2.
** (match-time captures should not be avoided by optimizations)
*/
static int getfirst (TTree *tree, const Charset *follow, Charset *firstset) {
 tailcall:
  switch (tree->tag) {
    case TChar: case TSet: case TAny: {
      tocharset(tree, firstset);
      return 0;
    }
    case TTrue: {
      loopset(i, firstset->cs[i] = follow->cs[i]);
      return 1;
    }
    case TFalse: {
      loopset(i, firstset->cs[i] = 0);
      return 0;
    }
    case TChoice: {
      Charset csaux;
      int e1 = getfirst(sib1(tree), follow, firstset);
      int e2 = getfirst(sib2(tree), follow, &csaux);
      loopset(i, firstset->cs[i] |= csaux.cs[i]);
      return e1 | e2;
    }
    case TSeq: {
      if (!nullable(sib1(tree))) {
        /* return getfirst(sib1(tree), fullset, firstset); */
        tree = sib1(tree); follow = fullset; goto tailcall;
      }
      else {  /* FIRST(p1 p2, fl) = FIRST(p1, FIRST(p2, fl)) */
        Charset csaux;
        int e2 = getfirst(sib2(tree), follow, &csaux);
        int e1 = getfirst(sib1(tree), &csaux, firstset);
        if (e1 == 0) return 0;  /* 'e1' ensures that first can be used */
        else if ((e1 | e2) & 2)  /* one of the children has a matchtime? */
          return 2;  /* pattern has a matchtime capture */
        else return e2;  /* else depends on 'e2' */
      }
    }
    case TRep: {
      getfirst(sib1(tree), follow, firstset);
      loopset(i, firstset->cs[i] |= follow->cs[i]);
      return 1;  /* accept the empty string */
    }
    case TCapture: case TGrammar: case TRule: {
      /* return getfirst(sib1(tree), follow, firstset); */
      tree = sib1(tree); goto tailcall;
    }
    case TRunTime: {  /* function invalidates any follow info. */
      int e = getfirst(sib1(tree), fullset, firstset);
      if (e) return 2;  /* function is not "protected"? */
      else return 0;  /* pattern inside capture ensures first can be used */
    }
    case TCall: {
      /* return getfirst(sib2(tree), follow, firstset); */
      tree = sib2(tree); goto tailcall;
    }
    case TAnd: {
      int e = getfirst(sib1(tree), follow, firstset);
      loopset(i, firstset->cs[i] &= follow->cs[i]);
      return e;
    }
    case TNot: {
      if (tocharset(sib1(tree), firstset)) {
        cs_complement(firstset);
        return 1;
      }
      /* else go through */
    }
    case TBehind: {  /* instruction gives no new information */
      /* call 'getfirst' to check for math-time captures */
      int e = getfirst(sib1(tree), follow, firstset);
      loopset(i, firstset->cs[i] = follow->cs[i]);  /* uses follow */
      return e | 1;  /* always can accept the empty string */
    }
    default: assert(0); return 0;
  }
}


/*
** If it returns true, then pattern can fail only depending on the next
** character of the subject
*/
static int headfail (TTree *tree) {
 tailcall:
  switch (tree->tag) {
    case TChar: case TSet: case TAny: case TFalse:
      return 1;
    case TTrue: case TRep: case TRunTime: case TNot:
    case TBehind:
      return 0;
    case TCapture: case TGrammar: case TRule: case TAnd:
      tree = sib1(tree); goto tailcall;  /* return headfail(sib1(tree)); */
    case TCall:
      tree = sib2(tree); goto tailcall;  /* return headfail(sib2(tree)); */
    case TSeq:
      if (!nofail(sib2(tree))) return 0;
      /* else return headfail(sib1(tree)); */
      tree = sib1(tree); goto tailcall;
    case TChoice:
      if (!headfail(sib1(tree))) return 0;
      /* else return headfail(sib2(tree)); */
      tree = sib2(tree); goto tailcall;
    default: assert(0); return 0;
  }
}


/*
** Check whether the code generation for the given tree can benefit
** from a follow set (to avoid computing the follow set when it is
** not needed)
*/
static int needfollow (TTree *tree) {
 tailcall:
  switch (tree->tag) {
    case TChar: case TSet: case TAny:
    case TFalse: case TTrue: case TAnd: case TNot:
    case TRunTime: case TGrammar: case TCall: case TBehind:
      return 0;
    case TChoice: case TRep:
      return 1;
    case TCapture:
      tree = sib1(tree); goto tailcall;
    case TSeq:
      tree = sib2(tree); goto tailcall;
    default: assert(0); return 0;
  }
}

/* }====================================================== */



/*
** {======================================================
** Code generation
** =======================================================
*/


/*
** size of an instruction
*/
int sizei (const Instruction *i) {
  switch((Opcode)i->i.code) {
    case ISet: case ISpan: return CHARSETINSTSIZE;
    case ITestSet: return CHARSETINSTSIZE + 1;
    case ITestChar: case ITestAny: case IChoice: case IJmp:
    case ICall: case IOpenCall: case ICommit: case IPartialCommit:
    case IBackCommit: return 2;
    default: return 1;
  }
}


/*
** state for the compiler
*/
typedef struct CompileState {
  Pattern *p;  /* pattern being compiled */
  int ncode;  /* next position in p->code to be filled */
  lua_State *L;
} CompileState;


/*
** code generation is recursive; 'opt' indicates that the code is
** being generated under a 'IChoice' operator jumping to its end.
** 'tt' points to a previous test protecting this code. 'fl' is
** the follow set of the pattern.
*/
static void codegen (CompileState *compst, TTree *tree, int opt, int tt,
                     const Charset *fl);


void reallocprog (lua_State *L, Pattern *p, int nsize) {
  void *ud;
  lua_Alloc f = lua_getallocf(L, &ud);
  void *newblock = f(ud, p->code, p->codesize * sizeof(Instruction),
                                  nsize * sizeof(Instruction));
  if (newblock == NULL && nsize > 0)
    luaL_error(L, "not enough memory");
  p->code = (Instruction *)newblock;
  p->codesize = nsize;
}


static int nextinstruction (CompileState *compst) {
  int size = compst->p->codesize;
  if (compst->ncode >= size)
    reallocprog(compst->L, compst->p, size * 2);
  return compst->ncode++;
}


#define getinstr(cs,i)		((cs)->p->code[i])


static int addinstruction (CompileState *compst, Opcode op, int aux) {
  int i = nextinstruction(compst);
  getinstr(compst, i).i.code = op;
  getinstr(compst, i).i.aux = aux;
  return i;
}


static int addoffsetinst (CompileState *compst, Opcode op) {
  int i = addinstruction(compst, op, 0);  /* instruction */
  addinstruction(compst, (Opcode)0, 0);  /* open space for offset */
  assert(op == ITestSet || sizei(&getinstr(compst, i)) == 2);
  return i;
}


static void setoffset (CompileState *compst, int instruction, int offset) {
  getinstr(compst, instruction + 1).offset = offset;
}


/*
** Add a capture instruction:
** 'op' is the capture instruction; 'cap' the capture kind;
** 'key' the key into ktable; 'aux' is optional offset
**
*/
static int addinstcap (CompileState *compst, Opcode op, int cap, int key,
                       int aux) {
  int i = addinstruction(compst, op, joinkindoff(cap, aux));
  getinstr(compst, i).i.key = key;
  return i;
}


#define gethere(compst) 	((compst)->ncode)

#define target(code,i)		((i) + code[i + 1].offset)


static void jumptothere (CompileState *compst, int instruction, int target) {
  if (instruction >= 0)
    setoffset(compst, instruction, target - instruction);
}


static void jumptohere (CompileState *compst, int instruction) {
  jumptothere(compst, instruction, gethere(compst));
}


/*
** Code an IChar instruction, or IAny if there is an equivalent
** test dominating it
*/
static void codechar (CompileState *compst, int c, int tt) {
  if (tt >= 0 && getinstr(compst, tt).i.code == ITestChar &&
                 getinstr(compst, tt).i.aux == c)
    addinstruction(compst, IAny, 0);
  else
    addinstruction(compst, IChar, c);
}


/*
** Add a charset posfix to an instruction
*/
static void addcharset (CompileState *compst, const byte *cs) {
  int p = gethere(compst);
  int i;
  for (i = 0; i < (int)CHARSETINSTSIZE - 1; i++)
    nextinstruction(compst);  /* space for buffer */
  /* fill buffer with charset */
  loopset(j, getinstr(compst, p).buff[j] = cs[j]);
}


/*
** code a char set, optimizing unit sets for IChar, "complete"
** sets for IAny, and empty sets for IFail; also use an IAny
** when instruction is dominated by an equivalent test.
*/
static void codecharset (CompileState *compst, const byte *cs, int tt) {
  int c = 0;  /* (=) to avoid warnings */
  Opcode op = charsettype(cs, &c);
  switch (op) {
    case IChar: codechar(compst, c, tt); break;
    case ISet: {  /* non-trivial set? */
      if (tt >= 0 && getinstr(compst, tt).i.code == ITestSet &&
          cs_equal(cs, getinstr(compst, tt + 2).buff))
        addinstruction(compst, IAny, 0);
      else {
        addinstruction(compst, ISet, 0);
        addcharset(compst, cs);
      }
      break;
    }
    default: addinstruction(compst, op, c); break;
  }
}


/*
** code a test set, optimizing unit sets for ITestChar, "complete"
** sets for ITestAny, and empty sets for IJmp (always fails).
** 'e' is true iff test should accept the empty string. (Test
** instructions in the current VM never accept the empty string.)
*/
static int codetestset (CompileState *compst, Charset *cs, int e) {
  if (e) return NOINST;  /* no test */
  else {
    int c = 0;
    Opcode op = charsettype(cs->cs, &c);
    switch (op) {
      case IFail: return addoffsetinst(compst, IJmp);  /* always jump */
      case IAny: return addoffsetinst(compst, ITestAny);
      case IChar: {
        int i = addoffsetinst(compst, ITestChar);
        getinstr(compst, i).i.aux = c;
        return i;
      }
      case ISet: {
        int i = addoffsetinst(compst, ITestSet);
        addcharset(compst, cs->cs);
        return i;
      }
      default: assert(0); return 0;
    }
  }
}


/*
** Find the final destination of a sequence of jumps
*/
static int finaltarget (Instruction *code, int i) {
  while (code[i].i.code == IJmp)
    i = target(code, i);
  return i;
}


/*
** final label (after traversing any jumps)
*/
static int finallabel (Instruction *code, int i) {
  return finaltarget(code, target(code, i));
}


/*
** <behind(p)> == behind n; <p>   (where n = fixedlen(p))
*/
static void codebehind (CompileState *compst, TTree *tree) {
  if (tree->u.n > 0)
    addinstruction(compst, IBehind, tree->u.n);
  codegen(compst, sib1(tree), 0, NOINST, fullset);
}


/*
** Choice; optimizations:
** - when p1 is headfail
** - when first(p1) and first(p2) are disjoint; than
** a character not in first(p1) cannot go to p1, and a character
** in first(p1) cannot go to p2 (at it is not in first(p2)).
** (The optimization is not valid if p1 accepts the empty string,
** as then there is no character at all...)
** - when p2 is empty and opt is true; a IPartialCommit can resuse
** the Choice already active in the stack.
*/
static void codechoice (CompileState *compst, TTree *p1, TTree *p2, int opt,
                        const Charset *fl) {
  int emptyp2 = (p2->tag == TTrue);
  Charset cs1, cs2;
  int e1 = getfirst(p1, fullset, &cs1);
  if (headfail(p1) ||
      (!e1 && (getfirst(p2, fl, &cs2), cs_disjoint(&cs1, &cs2)))) {
    /* <p1 / p2> == test (fail(p1)) -> L1 ; p1 ; jmp L2; L1: p2; L2: */
    int test = codetestset(compst, &cs1, 0);
    int jmp = NOINST;
    codegen(compst, p1, 0, test, fl);
    if (!emptyp2)
      jmp = addoffsetinst(compst, IJmp);
    jumptohere(compst, test);
    codegen(compst, p2, opt, NOINST, fl);
    jumptohere(compst, jmp);
  }
  else if (opt && emptyp2) {
    /* p1? == IPartialCommit; p1 */
    jumptohere(compst, addoffsetinst(compst, IPartialCommit));
    codegen(compst, p1, 1, NOINST, fullset);
  }
  else {
    /* <p1 / p2> ==
        test(fail(p1)) -> L1; choice L1; <p1>; commit L2; L1: <p2>; L2: */
    int pcommit;
    int test = codetestset(compst, &cs1, e1);
    int pchoice = addoffsetinst(compst, IChoice);
    codegen(compst, p1, emptyp2, test, fullset);
    pcommit = addoffsetinst(compst, ICommit);
    jumptohere(compst, pchoice);
    jumptohere(compst, test);
    codegen(compst, p2, opt, NOINST, fl);
    jumptohere(compst, pcommit);
  }
}


/*
** And predicate
** optimization: fixedlen(p) = n ==> <&p> == <p>; behind n
** (valid only when 'p' has no captures)
*/
static void codeand (CompileState *compst, TTree *tree, int tt) {
  int n = fixedlen(tree);
  if (n >= 0 && n <= MAXBEHIND && !hascaptures(tree)) {
    codegen(compst, tree, 0, tt, fullset);
    if (n > 0)
      addinstruction(compst, IBehind, n);
  }
  else {  /* default: Choice L1; p1; BackCommit L2; L1: Fail; L2: */
    int pcommit;
    int pchoice = addoffsetinst(compst, IChoice);
    codegen(compst, tree, 0, tt, fullset);
    pcommit = addoffsetinst(compst, IBackCommit);
    jumptohere(compst, pchoice);
    addinstruction(compst, IFail, 0);
    jumptohere(compst, pcommit);
  }
}


/*
** Captures: if pattern has fixed (and not too big) length, use
** a single IFullCapture instruction after the match; otherwise,
** enclose the pattern with OpenCapture - CloseCapture.
*/
static void codecapture (CompileState *compst, TTree *tree, int tt,
                         const Charset *fl) {
  int len = fixedlen(sib1(tree));
  if (len >= 0 && len <= MAXOFF && !hascaptures(sib1(tree))) {
    codegen(compst, sib1(tree), 0, tt, fl);
    addinstcap(compst, IFullCapture, tree->cap, tree->key, len);
  }
  else {
    addinstcap(compst, IOpenCapture, tree->cap, tree->key, 0);
    codegen(compst, sib1(tree), 0, tt, fl);
    addinstcap(compst, ICloseCapture, Cclose, 0, 0);
  }
}


static void coderuntime (CompileState *compst, TTree *tree, int tt) {
  addinstcap(compst, IOpenCapture, Cgroup, tree->key, 0);
  codegen(compst, sib1(tree), 0, tt, fullset);
  addinstcap(compst, ICloseRunTime, Cclose, 0, 0);
}


/*
** Repetion; optimizations:
** When pattern is a charset, can use special instruction ISpan.
** When pattern is head fail, or if it starts with characters that
** are disjoint from what follows the repetions, a simple test
** is enough (a fail inside the repetition would backtrack to fail
** again in the following pattern, so there is no need for a choice).
** When 'opt' is true, the repetion can reuse the Choice already
** active in the stack.
*/
static void coderep (CompileState *compst, TTree *tree, int opt,
                     const Charset *fl) {
  Charset st;
  if (tocharset(tree, &st)) {
    addinstruction(compst, ISpan, 0);
    addcharset(compst, st.cs);
  }
  else {
    int e1 = getfirst(tree, fullset, &st);
    if (headfail(tree) || (!e1 && cs_disjoint(&st, fl))) {
      /* L1: test (fail(p1)) -> L2; <p>; jmp L1; L2: */
      int jmp;
      int test = codetestset(compst, &st, 0);
      codegen(compst, tree, opt, test, fullset);
      jmp = addoffsetinst(compst, IJmp);
      jumptohere(compst, test);
      jumptothere(compst, jmp, test);
    }
    else {
      /* test(fail(p1)) -> L2; choice L2; L1: <p>; partialcommit L1; L2: */
      /* or (if 'opt'): partialcommit L1; L1: <p>; partialcommit L1; */
      int commit, l2;
      int test = codetestset(compst, &st, e1);
      int pchoice = NOINST;
      if (opt)
        jumptohere(compst, addoffsetinst(compst, IPartialCommit));
      else
        pchoice = addoffsetinst(compst, IChoice);
      l2 = gethere(compst);
      codegen(compst, tree, 0, NOINST, fullset);
      commit = addoffsetinst(compst, IPartialCommit);
      jumptothere(compst, commit, l2);
      jumptohere(compst, pchoice);
      jumptohere(compst, test);
    }
  }
}


/*
** Not predicate; optimizations:
** In any case, if first test fails, 'not' succeeds, so it can jump to
** the end. If pattern is headfail, that is all (it cannot fail
** in other parts); this case includes 'not' of simple sets. Otherwise,
** use the default code (a choice plus a failtwice).
*/
static void codenot (CompileState *compst, TTree *tree) {
  Charset st;
  int e = getfirst(tree, fullset, &st);
  int test = codetestset(compst, &st, e);
  if (headfail(tree))  /* test (fail(p1)) -> L1; fail; L1:  */
    addinstruction(compst, IFail, 0);
  else {
    /* test(fail(p))-> L1; choice L1; <p>; failtwice; L1:  */
    int pchoice = addoffsetinst(compst, IChoice);
    codegen(compst, tree, 0, NOINST, fullset);
    addinstruction(compst, IFailTwice, 0);
    jumptohere(compst, pchoice);
  }
  jumptohere(compst, test);
}


/*
** change open calls to calls, using list 'positions' to find
** correct offsets; also optimize tail calls
*/
static void correctcalls (CompileState *compst, int *positions,
                          int from, int to) {
  int i;
  Instruction *code = compst->p->code;
  for (i = from; i < to; i += sizei(&code[i])) {
    if (code[i].i.code == IOpenCall) {
      int n = code[i].i.key;  /* rule number */
      int rule = positions[n];  /* rule position */
      assert(rule == from || code[rule - 1].i.code == IRet);
      if (code[finaltarget(code, i + 2)].i.code == IRet)  /* call; ret ? */
        code[i].i.code = IJmp;  /* tail call */
      else
        code[i].i.code = ICall;
      jumptothere(compst, i, rule);  /* call jumps to respective rule */
    }
  }
  assert(i == to);
}


/*
** Code for a grammar:
** call L1; jmp L2; L1: rule 1; ret; rule 2; ret; ...; L2:
*/
static void codegrammar (CompileState *compst, TTree *grammar) {
  int positions[MAXRULES];
  int rulenumber = 0;
  TTree *rule;
  int firstcall = addoffsetinst(compst, ICall);  /* call initial rule */
  int jumptoend = addoffsetinst(compst, IJmp);  /* jump to the end */
  int start = gethere(compst);  /* here starts the initial rule */
  jumptohere(compst, firstcall);
  for (rule = sib1(grammar); rule->tag == TRule; rule = sib2(rule)) {
    positions[rulenumber++] = gethere(compst);  /* save rule position */
    codegen(compst, sib1(rule), 0, NOINST, fullset);  /* code rule */
    addinstruction(compst, IRet, 0);
  }
  assert(rule->tag == TTrue);
  jumptohere(compst, jumptoend);
  correctcalls(compst, positions, start, gethere(compst));
}


static void codecall (CompileState…