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2165 lines (1853 loc) · 56.1 KB
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/*
** $Id: lpeg.c,v 1.86 2008/03/07 17:20:19 roberto Exp $
** LPeg - PEG pattern matching for Lua
** Copyright 2007, Lua.org & PUC-Rio (see 'lpeg.html' for license)
** written by Roberto Ierusalimschy
*/
#include <assert.h>
#include <limits.h>
#include <stdio.h>
#include <string.h>
#include "lua.h"
#include "lauxlib.h"
#define VERSION "0.8"
#define PATTERN_T "pattern"
/* maximum call/backtrack levels */
#define MAXBACK 400
/* initial size for capture's list */
#define IMAXCAPTURES 600
/* 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 substitution value cache */
#define subscache(ptop) ((ptop) + 1)
/* index, on Lua stack, for capture list */
#define caplistidx(ptop) ((ptop) + 2)
/* index, on Lua stack, for pattern's fenv */
#define penvidx(ptop) ((ptop) + 3)
typedef unsigned char byte;
#define CHARSETSIZE ((UCHAR_MAX/CHAR_BIT) + 1)
typedef byte Charset[CHARSETSIZE];
typedef const char *(*PattFunc) (const void *ud,
const char *o, /* string start */
const char *s, /* current position */
const char *e); /* string end */
/* Virtual Machine's instructions */
typedef enum Opcode {
IAny, IChar, ISet, IZSet,
ITestAny, ITestChar, ITestSet, ITestZSet,
ISpan, ISpanZ,
IRet, IEnd,
IChoice, IJmp, ICall, IOpenCall,
ICommit, IPartialCommit, IBackCommit, IFailTwice, IFail, IGiveup,
IFunc,
IFullCapture, IEmptyCapture, IEmptyCaptureIdx,
IOpenCapture, ICloseCapture, ICloseRunTime
} Opcode;
#define ISJMP 1
#define ISCHECK 2
#define ISTEST 4
#define ISNOFAIL 8
#define ISCAPTURE 16
#define ISMOVABLE 32
#define ISFENVOFF 64
#define HASCHARSET 128
static const byte opproperties[] = {
/* IAny */ ISCHECK,
/* IChar */ ISCHECK,
/* ISet */ ISCHECK | HASCHARSET,
/* IZSet */ ISCHECK | HASCHARSET,
/* ITestAny */ ISJMP | ISTEST | ISNOFAIL,
/* ITestChar */ ISJMP | ISTEST | ISNOFAIL,
/* ITestSet */ ISJMP | ISTEST | ISNOFAIL | HASCHARSET,
/* ITestZSet */ ISJMP | ISTEST | ISNOFAIL | HASCHARSET,
/* ISpan */ ISNOFAIL | HASCHARSET,
/* ISpanZ */ ISNOFAIL | HASCHARSET,
/* IRet */ 0,
/* IEnd */ 0,
/* IChoice */ ISJMP,
/* IJmp */ ISJMP | ISNOFAIL,
/* ICall */ ISJMP,
/* IOpenCall */ ISFENVOFF,
/* ICommit */ ISJMP,
/* IPartialCommit */ ISJMP,
/* IBackCommit */ ISJMP,
/* IFailTwice */ 0,
/* IFail */ 0,
/* IGiveup */ 0,
/* IFunc */ 0,
/* IFullCapture */ ISCAPTURE | ISNOFAIL | ISFENVOFF,
/* IEmptyCapture */ ISCAPTURE | ISNOFAIL | ISMOVABLE,
/* IEmptyCaptureIdx */ISCAPTURE | ISNOFAIL | ISMOVABLE | ISFENVOFF,
/* IOpenCapture */ ISCAPTURE | ISNOFAIL | ISMOVABLE | ISFENVOFF,
/* ICloseCapture */ ISCAPTURE | ISNOFAIL | ISMOVABLE | ISFENVOFF,
/* ICloseRunTime */ ISCAPTURE | ISFENVOFF
};
typedef union Instruction {
struct Inst {
byte code;
byte aux;
short offset;
} i;
PattFunc f;
byte buff[1];
} Instruction;
static const Instruction giveup = {{IGiveup, 0, 0}};
#define getkind(op) ((op)->i.aux & 0xF)
#define getoff(op) (((op)->i.aux >> 4) & 0xF)
#define dest(p,x) ((x) + ((p)+(x))->i.offset)
#define MAXOFF 0xF
#define isprop(op,p) (opproperties[(op)->i.code] & (p))
#define isjmp(op) isprop(op, ISJMP)
#define iscapture(op) isprop(op, ISCAPTURE)
#define ischeck(op) isprop(op, ISCHECK)
#define istest(op) isprop(op, ISTEST)
#define isnofail(op) isprop(op, ISNOFAIL)
#define ismovable(op) isprop(op, ISMOVABLE)
#define isfenvoff(op) isprop(op, ISFENVOFF)
#define hascharset(op) isprop(op, HASCHARSET)
/* kinds of captures */
typedef enum CapKind {
Cclose, Cposition, Cconst, Cbackref, Carg, Csimple, Ctable, Cfunction,
Cquery, Cstring, Csubst, Caccum, Cruntime
} CapKind;
#define iscapnosize(k) ((k) == Cposition || (k) == Cconst)
typedef struct Capture {
const char *s; /* position */
short idx;
byte kind;
byte siz;
} Capture;
/* 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) - 1)/sizeof(Instruction) + 2)
/* size (in elements) for a ISet instruction */
#define CHARSETINSTSIZE instsize(CHARSETSIZE)
#define loopset(v,b) { int v; for (v = 0; v < CHARSETSIZE; v++) b; }
#define testchar(st,c) (((int)(st)[((c) >> 3)] & (1 << ((c) & 7))))
#define setchar(st,c) ((st)[(c) >> 3] |= (1 << ((c) & 7)))
static int sizei (const Instruction *i) {
if (hascharset(i)) return CHARSETINSTSIZE;
else if (i->i.code == IFunc) return i->i.offset;
else return 1;
}
static const char *val2str (lua_State *L, int idx) {
const char *k = lua_tostring(L, idx);
if (k != NULL)
return lua_pushfstring(L, "rule '%s'", k);
else
return lua_pushfstring(L, "rule <a %s>", luaL_typename(L, -1));
}
static int getposition (lua_State *L, int t, int i) {
int res;
lua_getfenv(L, -1);
lua_rawgeti(L, -1, i); /* get key from pattern's environment */
lua_gettable(L, t); /* get position from positions table */
res = lua_tointeger(L, -1);
if (res == 0) { /* key has no registered position? */
lua_rawgeti(L, -2, i); /* get key again */
return luaL_error(L, "%s is not defined in given grammar", val2str(L, -1));
}
lua_pop(L, 2); /* remove environment and position */
return res;
}
/*
** {======================================================
** Printing patterns
** =======================================================
*/
static void printcharset (const Charset st) {
int i;
printf("[");
for (i = 0; i <= UCHAR_MAX; i++) {
int first = i;
while (testchar(st, i) && i <= UCHAR_MAX) i++;
if (i - 1 == first) /* unary range? */
printf("(%02x)", first);
else if (i - 1 > first) /* non-empty range? */
printf("(%02x-%02x)", first, i - 1);
}
printf("]");
}
static void printcapkind (int kind) {
const char *const modes[] = {
"close", "position", "constant", "backref",
"argument", "simple", "table", "function",
"query", "string", "substitution", "accumulator",
"runtime"};
printf("%s", modes[kind]);
}
static void printjmp (const Instruction *op, const Instruction *p) {
printf("-> %ld", (long)(dest(0, p) - op));
}
static void printinst (const Instruction *op, const Instruction *p) {
const char *const names[] = {
"any", "char", "set", "zset",
"testany", "testchar", "testset", "testzset",
"span", "spanz",
"ret", "end",
"choice", "jmp", "call", "open_call",
"commit", "partial_commit", "back_commit", "failtwice", "fail", "giveup",
"func",
"fullcapture", "emptycapture", "emptycaptureidx", "opencapture",
"closecapture", "closeruntime"
};
printf("%02ld: %s ", (long)(p - op), names[p->i.code]);
switch ((Opcode)p->i.code) {
case IChar: {
printf("'%c'", p->i.aux);
break;
}
case ITestChar: {
printf("'%c'", p->i.aux);
printjmp(op, p);
break;
}
case IAny: {
printf("* %d", p->i.aux);
break;
}
case ITestAny: {
printf("* %d", p->i.aux);
printjmp(op, p);
break;
}
case IFullCapture: case IOpenCapture:
case IEmptyCapture: case IEmptyCaptureIdx:
case ICloseCapture: case ICloseRunTime: {
printcapkind(getkind(p));
printf("(n = %d) (off = %d)", getoff(p), p->i.offset);
break;
}
case ISet: case IZSet: case ISpan: case ISpanZ: {
printcharset((p+1)->buff);
break;
}
case ITestSet: case ITestZSet: {
printcharset((p+1)->buff);
printjmp(op, p);
break;
}
case IOpenCall: {
printf("-> %d", p->i.offset);
break;
}
case IChoice: {
printjmp(op, p);
printf(" (%d)", p->i.aux);
break;
}
case IJmp: case ICall: case ICommit:
case IPartialCommit: case IBackCommit: {
printjmp(op, p);
break;
}
default: break;
}
printf("\n");
}
static void printpatt (Instruction *p) {
Instruction *op = p;
for (;;) {
printinst(op, p);
if (p->i.code == IEnd) break;
p += sizei(p);
}
}
static void printcap (Capture *cap) {
printcapkind(cap->kind);
printf(" (idx: %d - size: %d) -> %p\n", cap->idx, cap->siz, cap->s);
}
static void printcaplist (Capture *cap) {
for (; cap->s; cap++) printcap(cap);
}
/* }====================================================== */
/*
** {======================================================
** Virtual Machine
** =======================================================
*/
typedef struct Stack {
const char *s;
const Instruction *p;
int caplevel;
} Stack;
static int runtimecap (lua_State *L, Capture *close, Capture *ocap,
const char *o, const char *s, int ptop);
static Capture *doublecap (lua_State *L, Capture *cap, int captop, int ptop) {
Capture *newc;
if (captop >= INT_MAX/((int)sizeof(Capture) * 2))
luaL_error(L, "too many captures");
newc = (Capture *)lua_newuserdata(L, captop * 2 * sizeof(Capture));
memcpy(newc, cap, captop * sizeof(Capture));
lua_replace(L, caplistidx(ptop));
return newc;
}
static void adddyncaptures (const char *s, Capture *base, int n, int fd) {
int i;
assert(base[0].kind == Cruntime && base[0].siz == 0);
base[0].idx = fd; /* first returned capture */
for (i = 1; i < n; i++) { /* add extra captures */
base[i].siz = 1; /* mark it as closed */
base[i].s = s;
base[i].kind = Cruntime;
base[i].idx = fd + i; /* stack index */
}
base[n].kind = Cclose; /* add closing entry */
base[n].siz = 1;
base[n].s = s;
}
static const char *match (lua_State *L,
const char *o, const char *s, const char *e,
Instruction *op, Capture *capture, int ptop) {
Stack stackbase[MAXBACK];
Stack *stacklimit = stackbase + MAXBACK;
Stack *stack = stackbase; /* point to first empty slot in stack */
int capsize = IMAXCAPTURES;
int captop = 0; /* point to first empty slot in captures */
const Instruction *p = op;
stack->p = &giveup; stack->s = s; stack->caplevel = 0; stack++;
for (;;) {
#if defined(DEBUG)
printf("s: |%s| stck: %d c: %d ", s, stack - stackbase, captop);
printinst(op, p);
#endif
switch ((Opcode)p->i.code) {
case IEnd: {
assert(stack == stackbase + 1);
capture[captop].kind = Cclose;
capture[captop].s = NULL;
return s;
}
case IGiveup: {
assert(stack == stackbase);
return NULL;
}
case IRet: {
assert(stack > stackbase && (stack - 1)->s == NULL);
p = (--stack)->p;
continue;
}
case IAny: {
int n = p->i.aux;
if (n > e - s) goto fail;
else { p++; s += n; }
continue;
}
case ITestAny: {
int n = p->i.aux;
if (n > e - s) p += p->i.offset;
else { p++; s += n; }
continue;
}
case IChar: {
if ((byte)*s != p->i.aux || s >= e) goto fail;
else { p++; s++; }
continue;
}
case ITestChar: {
if ((byte)*s != p->i.aux || s >= e) p += p->i.offset;
else { p++; s++; }
continue;
}
case ISet: {
int c = (unsigned char)*s;
if (!testchar((p+1)->buff, c)) goto fail;
else { p += CHARSETINSTSIZE; s++; }
continue;
}
case ITestSet: {
int c = (unsigned char)*s;
if (!testchar((p+1)->buff, c)) p += p->i.offset;
else { p += CHARSETINSTSIZE; s++; }
continue;
}
case IZSet: {
int c = (unsigned char)*s;
if (!testchar((p+1)->buff, c) || s >= e) goto fail;
else { p += CHARSETINSTSIZE; s++; }
continue;
}
case ITestZSet: {
int c = (unsigned char)*s;
if (!testchar((p+1)->buff, c) || s >= e) p += p->i.offset;
else { p += CHARSETINSTSIZE; s++; }
continue;
}
case ISpan: {
for (;; s++) {
int c = (unsigned char)*s;
if (!testchar((p+1)->buff, c)) break;
}
p += CHARSETINSTSIZE;
continue;
}
case ISpanZ: {
for (; s < e; s++) {
int c = (unsigned char)*s;
if (!testchar((p+1)->buff, c)) break;
}
p += CHARSETINSTSIZE;
continue;
}
case IFunc: {
const char *r = (p+1)->f((p+2)->buff, o, s, e);
if (r == NULL) goto fail;
s = r;
p += p->i.offset;
continue;
}
case IJmp: {
p += p->i.offset;
continue;
}
case IChoice: {
if (stack >= stacklimit)
return (luaL_error(L, "too many pending calls/choices"), (char *)0);
stack->p = dest(0, p);
stack->s = s - p->i.aux;
stack->caplevel = captop;
stack++;
p++;
continue;
}
case ICall: {
if (stack >= stacklimit)
return (luaL_error(L, "too many pending calls/choices"), (char *)0);
stack->s = NULL;
stack->p = p + 1; /* save return address */
stack++;
p += p->i.offset;
continue;
}
case ICommit: {
assert(stack > stackbase && (stack - 1)->s != NULL);
stack--;
p += p->i.offset;
continue;
}
case IPartialCommit: {
assert(stack > stackbase && (stack - 1)->s != NULL);
(stack - 1)->s = s;
(stack - 1)->caplevel = captop;
p += p->i.offset;
continue;
}
case IBackCommit: {
assert(stack > stackbase && (stack - 1)->s != NULL);
s = (--stack)->s;
p += p->i.offset;
continue;
}
case IFailTwice:
assert(stack > stackbase);
stack--;
/* go through */
case IFail:
fail: { /* pattern failed: try to backtrack */
do { /* remove pending calls */
assert(stack > stackbase);
s = (--stack)->s;
} while (s == NULL);
captop = stack->caplevel;
p = stack->p;
continue;
}
case ICloseRunTime: {
int fr = lua_gettop(L) + 1; /* stack index of first result */
int ncap = runtimecap(L, capture + captop, capture, o, s, ptop);
lua_Integer res = lua_tointeger(L, fr) - 1; /* offset */
int n = lua_gettop(L) - fr; /* number of new captures */
if (res == -1) { /* may not be a number */
if (!lua_toboolean(L, fr)) { /* false value? */
lua_settop(L, fr - 1); /* remove results */
goto fail; /* and fail */
}
else if (lua_isboolean(L, fr)) /* true? */
res = s - o; /* keep current position */
}
if (res < s - o || res > e - o)
luaL_error(L, "invalid position returned by match-time capture");
s = o + res; /* update current position */
captop -= ncap; /* remove nested captures */
lua_remove(L, fr); /* remove first result (offset) */
if (n > 0) { /* captures? */
if ((captop += n + 1) >= capsize) {
capture = doublecap(L, capture, captop, ptop);
capsize = 2 * captop;
}
adddyncaptures(s, capture + captop - n - 1, n, fr);
}
p++;
continue;
}
case ICloseCapture: {
const char *s1 = s - getoff(p);
assert(captop > 0);
if (capture[captop - 1].siz == 0 &&
s1 - capture[captop - 1].s < UCHAR_MAX) {
capture[captop - 1].siz = s1 - capture[captop - 1].s + 1;
p++;
continue;
}
else {
capture[captop].siz = 1; /* mark entry as closed */
goto capture;
}
}
case IEmptyCapture: case IEmptyCaptureIdx:
capture[captop].siz = 1; /* mark entry as closed */
goto capture;
case IOpenCapture:
capture[captop].siz = 0; /* mark entry as open */
goto capture;
case IFullCapture:
capture[captop].siz = getoff(p) + 1; /* save capture size */
capture: {
capture[captop].s = s - getoff(p);
capture[captop].idx = p->i.offset;
capture[captop].kind = getkind(p);
if (++captop >= capsize) {
capture = doublecap(L, capture, captop, ptop);
capsize = 2 * captop;
}
p++;
continue;
}
case IOpenCall: {
lua_rawgeti(L, penvidx(ptop), p->i.offset);
luaL_error(L, "reference to %s outside a grammar", val2str(L, -1));
}
default: assert(0); return NULL;
}
}
}
/* }====================================================== */
/*
** {======================================================
** Verifier
** =======================================================
*/
static int verify (lua_State *L, Instruction *op, const Instruction *p,
Instruction *e, int postable, int rule) {
static const char dummy[] = "";
Stack back[MAXBACK];
int backtop = 0; /* point to first empty slot in back */
while (p != e) {
switch ((Opcode)p->i.code) {
case IRet: {
p = back[--backtop].p;
continue;
}
case IChoice: {
if (backtop >= MAXBACK)
return luaL_error(L, "too many pending calls/choices");
back[backtop].p = dest(0, p);
back[backtop++].s = dummy;
p++;
continue;
}
case ICall: {
assert((p + 1)->i.code != IRet); /* no tail call */
if (backtop >= MAXBACK)
return luaL_error(L, "too many pending calls/choices");
back[backtop].s = NULL;
back[backtop++].p = p + 1;
goto dojmp;
}
case IOpenCall: {
int i;
if (postable == 0) /* grammar still not fixed? */
goto fail; /* to be verified later */
for (i = 0; i < backtop; i++) {
if (back[i].s == NULL && back[i].p == p + 1)
return luaL_error(L, "%s is left recursive", val2str(L, rule));
}
if (backtop >= MAXBACK)
return luaL_error(L, "too many pending calls/choices");
back[backtop].s = NULL;
back[backtop++].p = p + 1;
p = op + getposition(L, postable, p->i.offset);
continue;
}
case IBackCommit:
case ICommit: {
assert(backtop > 0 && p->i.offset > 0);
backtop--;
goto dojmp;
}
case IPartialCommit: {
assert(backtop > 0);
if (p->i.offset > 0) goto dojmp; /* forward jump */
else { /* loop will be detected when checking corresponding rule */
assert(postable != 0);
backtop--;
p++; /* just go on now */
continue;
}
}
case ITestAny:
case ITestChar: /* all these cases jump for empty subject */
case ITestSet:
case ITestZSet:
case IJmp:
dojmp: {
p += p->i.offset;
continue;
}
case IAny:
case IChar:
case ISet:
case IZSet:
case IFailTwice: /* assume that first level failed; try to backtrack */
goto fail;
case IFail: {
if (p->i.aux) { /* is an 'and' predicate? */
assert((p - 1)->i.code == IBackCommit && (p - 1)->i.offset == 2);
p++; /* pretend it succeeded and go ahead */
continue;
}
/* else go through */
}
fail: { /* pattern failed: try to backtrack */
do {
if (backtop-- == 0)
return 1; /* no more backtracking */
} while (back[backtop].s == NULL);
p = back[backtop].p;
continue;
}
case ISpan: case ISpanZ:
case IOpenCapture: case ICloseCapture:
case IEmptyCapture: case IEmptyCaptureIdx:
case IFullCapture: {
p += sizei(p);
continue;
}
case ICloseRunTime: {
goto fail; /* be liberal in this case */
}
case IFunc: {
const char *r = (p+1)->f((p+2)->buff, dummy, dummy, dummy);
if (r == NULL) goto fail;
p += p->i.offset;
continue;
}
case IEnd: /* cannot happen (should stop before it) */
default: assert(0); return 0;
}
}
assert(backtop == 0);
return 0;
}
static void checkrule (lua_State *L, Instruction *op, int from, int to,
int postable, int rule) {
int i;
int lastopen = 0; /* more recent OpenCall seen in the code */
for (i = from; i < to; i += sizei(op + i)) {
if (op[i].i.code == IPartialCommit && op[i].i.offset < 0) { /* loop? */
int start = dest(op, i);
assert(op[start - 1].i.code == IChoice && dest(op, start - 1) == i + 1);
if (start <= lastopen) { /* loop does contain an open call? */
if (!verify(L, op, op + start, op + i, postable, rule)) /* check body */
luaL_error(L, "possible infinite loop in %s", val2str(L, rule));
}
}
else if (op[i].i.code == IOpenCall)
lastopen = i;
}
assert(op[i - 1].i.code == IRet);
verify(L, op, op + from, op + to - 1, postable, rule);
}
/* }====================================================== */
/*
** {======================================================
** Building Patterns
** =======================================================
*/
enum charsetanswer { NOINFO, ISCHARSET, VALIDSTARTS };
typedef struct CharsetTag {
enum charsetanswer tag;
Charset cs;
} CharsetTag;
static Instruction *getpatt (lua_State *L, int idx, int *size);
static void check2test (Instruction *p, int n) {
assert(ischeck(p));
p->i.code += ITestAny - IAny;
p->i.offset = n;
}
/*
** invert array slice p[0]-p[e] (both inclusive)
*/
static void invert (Instruction *p, int e) {
int i;
for (i = 0; i < e; i++, e--) {
Instruction temp = p[i];
p[i] = p[e];
p[e] = temp;
}
}
/*
** rotate array slice p[0]-p[e] (both inclusive) 'n' steps
** to the 'left'
*/
static void rotate (Instruction *p, int e, int n) {
invert(p, n - 1);
invert(p + n, e - n);
invert(p, e);
}
#define op_step(p) ((p)->i.code == IAny ? (p)->i.aux : 1)
static int skipchecks (Instruction *p, int up, int *pn) {
int i, n = 0;
for (i = 0; ischeck(p + i); i += sizei(p + i)) {
int st = op_step(p + i);
if (n + st > MAXOFF - up) break;
n += st;
}
*pn = n;
return i;
}
#define ismovablecap(op) (ismovable(op) && getoff(op) < MAXOFF)
static void optimizecaptures (Instruction *p) {
int i;
int limit = 0;
for (i = 0; p[i].i.code != IEnd; i += sizei(p + i)) {
if (isjmp(p + i) && dest(p, i) >= limit)
limit = dest(p, i) + 1; /* do not optimize jump targets */
else if (i >= limit && ismovablecap(p + i) && ischeck(p + i + 1)) {
int end, n, j; /* found a border capture|check */
int maxoff = getoff(p + i);
int start = i;
/* find first capture in the group */
while (start > limit && ismovablecap(p + start - 1)) {
start--;
if (getoff(p + start) > maxoff) maxoff = getoff(p + start);
}
end = skipchecks(p + i + 1, maxoff, &n) + i; /* find last check */
if (n == 0) continue; /* first check is too big to move across */
assert(n <= MAXOFF && start <= i && i < end);
for (j = start; j <= i; j++)
p[j].i.aux += (n << 4); /* correct offset of captures to be moved */
rotate(p + start, end - start, i - start + 1); /* move them up */
i = end;
assert(ischeck(p + start) && iscapture(p + i));
}
}
}
static int target (Instruction *p, int i) {
while (p[i].i.code == IJmp) i += p[i].i.offset;
return i;
}
static void optimizejumps (Instruction *p) {
int i;
for (i = 0; p[i].i.code != IEnd; i += sizei(p + i)) {
if (isjmp(p + i))
p[i].i.offset = target(p, dest(p, i)) - i;
}
}
static void optimizechoice (Instruction *p) {
assert(p->i.code == IChoice);
if (ischeck(p + 1)) {
int lc = sizei(p + 1);
rotate(p, lc, 1);
assert(ischeck(p) && (p + lc)->i.code == IChoice);
(p + lc)->i.aux = op_step(p);
check2test(p, (p + lc)->i.offset);
(p + lc)->i.offset -= lc;
}
}
/*
** A 'headfail' pattern is a pattern that can only fails in its first
** instruction, which must be a check.
*/
static int isheadfail (Instruction *p) {
if (!ischeck(p)) return 0;
/* check that other operations cannot fail */
for (p += sizei(p); p->i.code != IEnd; p += sizei(p))
if (!isnofail(p)) return 0;
return 1;
}
#define checkpattern(L, idx) ((Instruction *)luaL_checkudata(L, idx, PATTERN_T))
static int jointable (lua_State *L, int p1) {
int n, n1, i;
lua_getfenv(L, p1);
n1 = lua_objlen(L, -1); /* number of elements in p1's env */
lua_getfenv(L, -2);
if (n1 == 0 || lua_equal(L, -2, -1)) {
lua_pop(L, 2);
return 0; /* no need to change anything */
}
n = lua_objlen(L, -1); /* number of elements in p's env */
if (n == 0) {
lua_pop(L, 1); /* removes p env */
lua_setfenv(L, -2); /* p now shares p1's env */
return 0; /* no need to correct anything */
}
lua_createtable(L, n + n1, 0);
/* stack: p; p1 env; p env; new p env */
for (i = 1; i <= n; i++) {
lua_rawgeti(L, -2, i);
lua_rawseti(L, -2, i);
}
for (i = 1; i <= n1; i++) {
lua_rawgeti(L, -3, i);
lua_rawseti(L, -2, n + i);
}
lua_setfenv(L, -4); /* new table becomes p env */
lua_pop(L, 2); /* remove p1 env and old p env */
return n;
}
#define copypatt(p1,p2,sz) memcpy(p1, p2, (sz) * sizeof(Instruction));
#define pattsize(L,idx) (lua_objlen(L, idx)/sizeof(Instruction) - 1)
static int addpatt (lua_State *L, Instruction *p, int p1idx) {
Instruction *p1 = (Instruction *)lua_touserdata(L, p1idx);
int sz = pattsize(L, p1idx);
int corr = jointable(L, p1idx);
copypatt(p, p1, sz + 1);
if (corr != 0) {
Instruction *px;
for (px = p; px < p + sz; px += sizei(px)) {
if (isfenvoff(px) && px->i.offset != 0)
px->i.offset += corr;
}
}
return sz;
}
static void setinstaux (Instruction *i, Opcode op, int offset, int aux) {
i->i.code = op;
i->i.offset = offset;
i->i.aux = aux;
}
#define setinst(i,op,off) setinstaux(i,op,off,0)
#define setinstcap(i,op,idx,k,n) setinstaux(i,op,idx,((k) | ((n) << 4)))
static int value2fenv (lua_State *L, int vidx) {
lua_createtable(L, 1, 0);
lua_pushvalue(L, vidx);
lua_rawseti(L, -2, 1);
lua_setfenv(L, -2);
return 1;
}
static Instruction *newpatt (lua_State *L, size_t n) {
Instruction *p;
if (n >= MAXPATTSIZE - 1)
luaL_error(L, "pattern too big");
p = (Instruction *)lua_newuserdata(L, (n + 1) * sizeof(Instruction));
luaL_getmetatable(L, PATTERN_T);
lua_setmetatable(L, -2);
setinst(p + n, IEnd, 0);
return p;
}
static void fillcharset (Instruction *p, Charset cs) {
switch (p[0].i.code) {
case IZSet: case ITestZSet:
assert(testchar(p[1].buff, '\0'));
/* go through */
case ISet: case ITestSet: {
loopset(i, cs[i] = p[1].buff[i]);
break;
}
case IChar: case ITestChar: {
loopset(i, cs[i] = 0);