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/*
** $Id: lptree.c,v 1.10 2013/04/12 16:30:33 roberto Exp $
** Copyright 2013, Lua.org & PUC-Rio (see 'lpeg.html' for license)
*/
#include <ctype.h>
#include <limits.h>
#include <string.h>
#include "lua.h"
#include "lauxlib.h"
#include "lptypes.h"
#include "lpcap.h"
#include "lpcode.h"
#include "lpprint.h"
#include "lptree.h"
/* number of siblings for each tree */
const byte numsiblings[] = {
0, 0, 0, /* char, set, any */
0, 0, /* true, false */
1, /* rep */
2, 2, /* seq, choice */
1, 1, /* not, and */
0, 0, 2, 1, /* call, opencall, rule, grammar */
1, /* behind */
1, 1 /* capture, runtime capture */
};
static TTree *newgrammar (lua_State *L, int arg);
/*
** returns a reasonable name for value at index 'idx' on the stack
*/
static const char *val2str (lua_State *L, int idx) {
const char *k = lua_tostring(L, idx);
if (k != NULL)
return lua_pushfstring(L, "%s", k);
else
return lua_pushfstring(L, "(a %s)", luaL_typename(L, idx));
}
/*
** Fix a TOpenCall into a TCall node, using table 'postable' to
** translate a key to its rule address in the tree. Raises an
** error if key does not exist.
*/
static void fixonecall (lua_State *L, int postable, TTree *g, TTree *t) {
int n;
lua_rawgeti(L, -1, t->key); /* get rule's name */
lua_gettable(L, postable); /* query name in position table */
n = lua_tonumber(L, -1); /* get (absolute) position */
lua_pop(L, 1); /* remove position */
if (n == 0) { /* no position? */
lua_rawgeti(L, -1, t->key); /* get rule's name again */
luaL_error(L, "rule '%s' undefined in given grammar", val2str(L, -1));
}
t->tag = TCall;
t->u.ps = n - (t - g); /* position relative to node */
assert(sib2(t)->tag == TRule);
sib2(t)->key = t->key;
}
/*
** Transform left associative constructions into right
** associative ones, for sequence and choice; that is:
** (t11 + t12) + t2 => t11 + (t12 + t2)
** (t11 * t12) * t2 => t11 * (t12 * t2)
** (that is, Op (Op t11 t12) t2 => Op t11 (Op t12 t2))
*/
static void correctassociativity (TTree *tree) {
TTree *t1 = sib1(tree);
assert(tree->tag == TChoice || tree->tag == TSeq);
while (t1->tag == tree->tag) {
int n1size = tree->u.ps - 1; /* t1 == Op t11 t12 */
int n11size = t1->u.ps - 1;
int n12size = n1size - n11size - 1;
memmove(sib1(tree), sib1(t1), n11size * sizeof(TTree)); /* move t11 */
tree->u.ps = n11size + 1;
sib2(tree)->tag = tree->tag;
sib2(tree)->u.ps = n12size + 1;
}
}
/*
** Make final adjustments in a tree. Fix open calls in tree 't',
** making them refer to their respective rules or raising appropriate
** errors (if not inside a grammar). Correct associativity of associative
** constructions (making them right associative). Assume that tree's
** ktable is at the top of the stack (for error messages).
*/
static void finalfix (lua_State *L, int postable, TTree *g, TTree *t) {
tailcall:
switch (t->tag) {
case TGrammar: /* subgrammars were already fixed */
return;
case TOpenCall: {
if (g != NULL) /* inside a grammar? */
fixonecall(L, postable, g, t);
else { /* open call outside grammar */
lua_rawgeti(L, -1, t->key);
luaL_error(L, "rule '%s' used outside a grammar", val2str(L, -1));
}
break;
}
case TSeq: case TChoice:
correctassociativity(t);
break;
}
switch (numsiblings[t->tag]) {
case 1: /* finalfix(L, postable, g, sib1(t)); */
t = sib1(t); goto tailcall;
case 2:
finalfix(L, postable, g, sib1(t));
t = sib2(t); goto tailcall; /* finalfix(L, postable, g, sib2(t)); */
default: assert(numsiblings[t->tag] == 0); break;
}
}
/*
** {======================================================
** Tree generation
** =======================================================
*/
/*
** In 5.2, could use 'luaL_testudata'...
*/
static int testpattern (lua_State *L, int idx) {
if (lua_touserdata(L, idx)) { /* value is a userdata? */
if (lua_getmetatable(L, idx)) { /* does it have a metatable? */
luaL_getmetatable(L, PATTERN_T);
if (lua_rawequal(L, -1, -2)) { /* does it have the correct mt? */
lua_pop(L, 2); /* remove both metatables */
return 1;
}
}
}
return 0;
}
static Pattern *getpattern (lua_State *L, int idx) {
return (Pattern *)luaL_checkudata(L, idx, PATTERN_T);
}
static int getsize (lua_State *L, int idx) {
return (lua_objlen(L, idx) - sizeof(Pattern)) / sizeof(TTree) + 1;
}
static TTree *gettree (lua_State *L, int idx, int *len) {
Pattern *p = getpattern(L, idx);
if (len)
*len = getsize(L, idx);
return p->tree;
}
/*
** create a pattern
*/
static TTree *newtree (lua_State *L, int len) {
size_t size = (len - 1) * sizeof(TTree) + sizeof(Pattern);
Pattern *p = (Pattern *)lua_newuserdata(L, size);
luaL_getmetatable(L, PATTERN_T);
lua_setmetatable(L, -2);
p->code = NULL; p->codesize = 0;
return p->tree;
}
static TTree *newleaf (lua_State *L, int tag) {
TTree *tree = newtree(L, 1);
tree->tag = tag;
return tree;
}
static TTree *newcharset (lua_State *L) {
TTree *tree = newtree(L, bytes2slots(CHARSETSIZE) + 1);
tree->tag = TSet;
loopset(i, treebuffer(tree)[i] = 0);
return tree;
}
/*
** add to tree a sequence where first sibling is 'sib' (with size
** 'sibsize'); returns position for second sibling
*/
static TTree *seqaux (TTree *tree, TTree *sib, int sibsize) {
tree->tag = TSeq; tree->u.ps = sibsize + 1;
memcpy(sib1(tree), sib, sibsize * sizeof(TTree));
return sib2(tree);
}
/*
** Add element 'idx' to 'ktable' of pattern at the top of the stack;
** create new 'ktable' if necessary. Return index of new element.
*/
static int addtoktable (lua_State *L, int idx) {
if (idx == 0 || lua_isnil(L, idx)) /* no actual value to insert? */
return 0;
else {
int n;
lua_getfenv(L, -1); /* get ktable from pattern */
n = lua_objlen(L, -1);
if (n == 0) { /* is it empty/non-existent? */
lua_pop(L, 1); /* remove it */
lua_createtable(L, 1, 0); /* create a fresh table */
}
lua_pushvalue(L, idx); /* element to be added */
lua_rawseti(L, -2, n + 1);
lua_setfenv(L, -2); /* set it as ktable for pattern */
return n + 1;
}
}
/*
** Build a sequence of 'n' nodes, each with tag 'tag' and 'u.n' got
** from the array 's' (or 0 if array is NULL). (TSeq is binary, so it
** must build a sequence of sequence of sequence...)
*/
static void fillseq (TTree *tree, int tag, int n, const char *s) {
int i;
for (i = 0; i < n - 1; i++) { /* initial n-1 copies of Seq tag; Seq ... */
tree->tag = TSeq; tree->u.ps = 2;
sib1(tree)->tag = tag;
sib1(tree)->u.n = s ? (byte)s[i] : 0;
tree = sib2(tree);
}
tree->tag = tag; /* last one does not need TSeq */
tree->u.n = s ? (byte)s[i] : 0;
}
/*
** Numbers as patterns:
** 0 == true (always match); n == TAny repeated 'n' times;
** -n == not (TAny repeated 'n' times)
*/
static TTree *numtree (lua_State *L, int n) {
if (n == 0)
return newleaf(L, TTrue);
else {
TTree *tree, *nd;
if (n > 0)
tree = nd = newtree(L, 2 * n - 1);
else { /* negative: code it as !(-n) */
n = -n;
tree = newtree(L, 2 * n);
tree->tag = TNot;
nd = sib1(tree);
}
fillseq(nd, TAny, n, NULL); /* sequence of 'n' any's */
return tree;
}
}
/*
** Convert value at index 'idx' to a pattern
*/
static TTree *getpatt (lua_State *L, int idx, int *len) {
TTree *tree;
switch (lua_type(L, idx)) {
case LUA_TSTRING: {
size_t slen;
const char *s = lua_tolstring(L, idx, &slen); /* get string */
if (slen == 0) /* empty? */
tree = newleaf(L, TTrue); /* always match */
else {
tree = newtree(L, 2 * (slen - 1) + 1);
fillseq(tree, TChar, slen, s); /* sequence of 'slen' chars */
}
break;
}
case LUA_TNUMBER: {
int n = lua_tointeger(L, idx);
tree = numtree(L, n);
break;
}
case LUA_TBOOLEAN: {
tree = (lua_toboolean(L, idx) ? newleaf(L, TTrue) : newleaf(L, TFalse));
break;
}
case LUA_TTABLE: {
tree = newgrammar(L, idx);
break;
}
case LUA_TFUNCTION: {
tree = newtree(L, 2);
tree->tag = TRunTime;
tree->key = addtoktable(L, idx);
sib1(tree)->tag = TTrue;
break;
}
default: {
return gettree(L, idx, len);
}
}
lua_replace(L, idx); /* put new tree into 'idx' slot */
if (len)
*len = getsize(L, idx);
return tree;
}
/*
** Return the number of elements in the ktable of pattern at 'idx'.
** In Lua 5.2, default "environment" for patterns is nil, not
** a table. Treat it as an empty table. In Lua 5.1, assumes that
** the environment has no numeric indices (len == 0)
*/
static int ktablelen (lua_State *L, int idx) {
if (!lua_istable(L, idx)) return 0;
else return lua_objlen(L, idx);
}
/*
** Concatentate the contents of table 'idx1' into table 'idx2'.
** (Assume that both indices are negative.)
** Return the original length of table 'idx2'
*/
static int concattable (lua_State *L, int idx1, int idx2) {
int i;
int n1 = ktablelen(L, idx1);
int n2 = ktablelen(L, idx2);
if (n1 == 0) return 0; /* nothing to correct */
for (i = 1; i <= n1; i++) {
lua_rawgeti(L, idx1, i);
lua_rawseti(L, idx2 - 1, n2 + i); /* correct 'idx2' */
}
return n2;
}
/*
** Make a merge of ktables from p1 and p2 the ktable for the new
** pattern at the top of the stack.
*/
static int joinktables (lua_State *L, int p1, int p2) {
int n1, n2;
lua_getfenv(L, p1); /* get ktables */
lua_getfenv(L, p2);
n1 = ktablelen(L, -2);
n2 = ktablelen(L, -1);
if (n1 == 0 && n2 == 0) { /* are both tables empty? */
lua_pop(L, 2); /* nothing to be done; pop tables */
return 0; /* nothing to correct */
}
if (n2 == 0 || lua_equal(L, -2, -1)) { /* second table is empty or equal? */
lua_pop(L, 1); /* pop 2nd table */
lua_setfenv(L, -2); /* set 1st ktable into new pattern */
return 0; /* nothing to correct */
}
if (n1 == 0) { /* first table is empty? */
lua_setfenv(L, -3); /* set 2nd table into new pattern */
lua_pop(L, 1); /* pop 1st table */
return 0; /* nothing to correct */
}
else {
lua_createtable(L, n1 + n2, 0); /* create ktable for new pattern */
/* stack: new p; ktable p1; ktable p2; new ktable */
concattable(L, -3, -1); /* from p1 into new ktable */
concattable(L, -2, -1); /* from p2 into new ktable */
lua_setfenv(L, -4); /* new ktable becomes p env */
lua_pop(L, 2); /* pop other ktables */
return n1; /* correction for indices from p2 */
}
}
static void correctkeys (TTree *tree, int n) {
if (n == 0) return; /* no correction? */
tailcall:
switch (tree->tag) {
case TOpenCall: case TCall: case TRunTime: case TRule: {
if (tree->key > 0)
tree->key += n;
break;
}
case TCapture: {
if (tree->key > 0 && tree->cap != Carg && tree->cap != Cnum)
tree->key += n;
break;
}
default: break;
}
switch (numsiblings[tree->tag]) {
case 1: /* correctkeys(sib1(tree), n); */
tree = sib1(tree); goto tailcall;
case 2:
correctkeys(sib1(tree), n);
tree = sib2(tree); goto tailcall; /* correctkeys(sib2(tree), n); */
default: assert(numsiblings[tree->tag] == 0); break;
}
}
/*
** copy 'ktable' of element 'idx' to new tree (on top of stack)
*/
static void copyktable (lua_State *L, int idx) {
lua_getfenv(L, idx);
lua_setfenv(L, -2);
}
/*
** merge 'ktable' from rule at stack index 'idx' into 'ktable'
** from tree at the top of the stack, and correct corresponding
** tree.
*/
static void mergektable (lua_State *L, int idx, TTree *rule) {
int n;
lua_getfenv(L, -1); /* get ktables */
lua_getfenv(L, idx);
n = concattable(L, -1, -2);
lua_pop(L, 2); /* remove both ktables */
correctkeys(rule, n);
}
/*
** create a new tree, whith a new root and one sibling.
** Sibling must be on the Lua stack, at index 1.
*/
static TTree *newroot1sib (lua_State *L, int tag) {
int s1;
TTree *tree1 = getpatt(L, 1, &s1);
TTree *tree = newtree(L, 1 + s1); /* create new tree */
tree->tag = tag;
memcpy(sib1(tree), tree1, s1 * sizeof(TTree));
copyktable(L, 1);
return tree;
}
/*
** create a new tree, whith a new root and 2 siblings.
** Siblings must be on the Lua stack, first one at index 1.
*/
static TTree *newroot2sib (lua_State *L, int tag) {
int s1, s2;
TTree *tree1 = getpatt(L, 1, &s1);
TTree *tree2 = getpatt(L, 2, &s2);
TTree *tree = newtree(L, 1 + s1 + s2); /* create new tree */
tree->tag = tag;
tree->u.ps = 1 + s1;
memcpy(sib1(tree), tree1, s1 * sizeof(TTree));
memcpy(sib2(tree), tree2, s2 * sizeof(TTree));
correctkeys(sib2(tree), joinktables(L, 1, 2));
return tree;
}
static int lp_P (lua_State *L) {
luaL_checkany(L, 1);
getpatt(L, 1, NULL);
lua_settop(L, 1);
return 1;
}
/*
** sequence operator; optimizations:
** false x => false, x true => x, true x => x
** (cannot do x . false => false because x may have runtime captures)
*/
static int lp_seq (lua_State *L) {
TTree *tree1 = getpatt(L, 1, NULL);
TTree *tree2 = getpatt(L, 2, NULL);
if (tree1->tag == TFalse || tree2->tag == TTrue)
lua_pushvalue(L, 1); /* false . x == false, x . true = x */
else if (tree1->tag == TTrue)
lua_pushvalue(L, 2); /* true . x = x */
else
newroot2sib(L, TSeq);
return 1;
}
/*
** choice operator; optimizations:
** charset / charset => charset
** true / x => true, x / false => x, false / x => x
** (x / true is not equivalent to true)
*/
static int lp_choice (lua_State *L) {
Charset st1, st2;
TTree *t1 = getpatt(L, 1, NULL);
TTree *t2 = getpatt(L, 2, NULL);
if (tocharset(t1, &st1) && tocharset(t2, &st2)) {
TTree *t = newcharset(L);
loopset(i, treebuffer(t)[i] = st1.cs[i] | st2.cs[i]);
}
else if (nofail(t1) || t2->tag == TFalse)
lua_pushvalue(L, 1); /* true / x => true, x / false => x */
else if (t1->tag == TFalse)
lua_pushvalue(L, 2); /* false / x => x */
else
newroot2sib(L, TChoice);
return 1;
}
/*
** p^n
*/
static int lp_star (lua_State *L) {
int size1;
int n = luaL_checkint(L, 2);
TTree *tree1 = gettree(L, 1, &size1);
if (n >= 0) { /* seq tree1 (seq tree1 ... (seq tree1 (rep tree1))) */
TTree *tree = newtree(L, (n + 1) * (size1 + 1));
if (nullable(tree1))
luaL_error(L, "loop body may accept empty string");
while (n--) /* repeat 'n' times */
tree = seqaux(tree, tree1, size1);
tree->tag = TRep;
memcpy(sib1(tree), tree1, size1 * sizeof(TTree));
}
else { /* choice (seq tree1 ... choice tree1 true ...) true */
TTree *tree;
n = -n;
/* size = (choice + seq + tree1 + true) * n, but the last has no seq */
tree = newtree(L, n * (size1 + 3) - 1);
for (; n > 1; n--) { /* repeat (n - 1) times */
tree->tag = TChoice; tree->u.ps = n * (size1 + 3) - 2;
sib2(tree)->tag = TTrue;
tree = sib1(tree);
tree = seqaux(tree, tree1, size1);
}
tree->tag = TChoice; tree->u.ps = size1 + 1;
sib2(tree)->tag = TTrue;
memcpy(sib1(tree), tree1, size1 * sizeof(TTree));
}
copyktable(L, 1);
return 1;
}
/*
** #p == &p
*/
static int lp_and (lua_State *L) {
newroot1sib(L, TAnd);
return 1;
}
/*
** -p == !p
*/
static int lp_not (lua_State *L) {
newroot1sib(L, TNot);
return 1;
}
/*
** [t1 - t2] == Seq (Not t2) t1
** If t1 and t2 are charsets, make their difference.
*/
static int lp_sub (lua_State *L) {
Charset st1, st2;
int s1, s2;
TTree *t1 = getpatt(L, 1, &s1);
TTree *t2 = getpatt(L, 2, &s2);
if (tocharset(t1, &st1) && tocharset(t2, &st2)) {
TTree *t = newcharset(L);
loopset(i, treebuffer(t)[i] = st1.cs[i] & ~st2.cs[i]);
}
else {
TTree *tree = newtree(L, 2 + s1 + s2);
tree->tag = TSeq; /* sequence of... */
tree->u.ps = 2 + s2;
sib1(tree)->tag = TNot; /* ...not... */
memcpy(sib1(sib1(tree)), t2, s2 * sizeof(TTree)); /* ...t2 */
memcpy(sib2(tree), t1, s1 * sizeof(TTree)); /* ... and t1 */
correctkeys(sib1(tree), joinktables(L, 1, 2));
}
return 1;
}
static int lp_set (lua_State *L) {
size_t l;
const char *s = luaL_checklstring(L, 1, &l);
TTree *tree = newcharset(L);
while (l--) {
setchar(treebuffer(tree), (byte)(*s));
s++;
}
return 1;
}
static int lp_range (lua_State *L) {
int arg;
int top = lua_gettop(L);
TTree *tree = newcharset(L);
for (arg = 1; arg <= top; arg++) {
int c;
size_t l;
const char *r = luaL_checklstring(L, arg, &l);
luaL_argcheck(L, l == 2, arg, "range must have two characters");
for (c = (byte)r[0]; c <= (byte)r[1]; c++)
setchar(treebuffer(tree), c);
}
return 1;
}
/*
** Look-behind predicate
*/
static int lp_behind (lua_State *L) {
TTree *tree;
TTree *tree1 = getpatt(L, 1, NULL);
int n = fixedlen(tree1);
luaL_argcheck(L, !hascaptures(tree1), 1, "pattern have captures");
luaL_argcheck(L, n > 0, 1, "pattern may not have fixed length");
luaL_argcheck(L, n <= MAXBEHIND, 1, "pattern too long to look behind");
tree = newroot1sib(L, TBehind);
tree->u.n = n;
return 1;
}
/*
** Create a non-terminal
*/
static int lp_V (lua_State *L) {
TTree *tree = newleaf(L, TOpenCall);
luaL_argcheck(L, !lua_isnoneornil(L, 1), 1, "non-nil value expected");
tree->key = addtoktable(L, 1);
return 1;
}
/*
** Create a tree for a non-empty capture, with a body and
** optionally with an associated Lua value (at index 'labelidx' in the
** stack)
*/
static int capture_aux (lua_State *L, int cap, int labelidx) {
TTree *tree = newroot1sib(L, TCapture);
tree->cap = cap;
tree->key = addtoktable(L, labelidx);
return 1;
}
/*
** Fill a tree with an empty capture, using an empty (TTrue) sibling.
*/
static TTree *auxemptycap (lua_State *L, TTree *tree, int cap, int idx) {
tree->tag = TCapture;
tree->cap = cap;
tree->key = addtoktable(L, idx);
sib1(tree)->tag = TTrue;
return tree;
}
/*
** Create a tree for an empty capture
*/
static TTree *newemptycap (lua_State *L, int cap, int idx) {
return auxemptycap(L, newtree(L, 2), cap, idx);
}
/*
** Captures with syntax p / v
** (function capture, query capture, string capture, or number capture)
*/
static int lp_divcapture (lua_State *L) {
switch (lua_type(L, 2)) {
case LUA_TFUNCTION: return capture_aux(L, Cfunction, 2);
case LUA_TTABLE: return capture_aux(L, Cquery, 2);
case LUA_TSTRING: return capture_aux(L, Cstring, 2);
case LUA_TNUMBER: {
int n = lua_tointeger(L, 2);
TTree *tree = newroot1sib(L, TCapture);
luaL_argcheck(L, 0 <= n && n <= SHRT_MAX, 1, "invalid number");
tree->cap = Cnum;
tree->key = n;
return 1;
}
default: return luaL_argerror(L, 2, "invalid replacement value");
}
}
static int lp_substcapture (lua_State *L) {
return capture_aux(L, Csubst, 0);
}
static int lp_tablecapture (lua_State *L) {
return capture_aux(L, Ctable, 0);
}
static int lp_groupcapture (lua_State *L) {
if (lua_isnoneornil(L, 2))
return capture_aux(L, Cgroup, 0);
else {
luaL_checkstring(L, 2);
return capture_aux(L, Cgroup, 2);
}
}
static int lp_foldcapture (lua_State *L) {
luaL_checktype(L, 2, LUA_TFUNCTION);
return capture_aux(L, Cfold, 2);
}
static int lp_simplecapture (lua_State *L) {
return capture_aux(L, Csimple, 0);
}
static int lp_poscapture (lua_State *L) {
newemptycap(L, Cposition, 0);
return 1;
}
static int lp_argcapture (lua_State *L) {
int n = luaL_checkint(L, 1);
TTree *tree = newemptycap(L, Carg, 0);
tree->key = n;
luaL_argcheck(L, 0 < n && n <= SHRT_MAX, 1, "invalid argument index");
return 1;
}
static int lp_backref (lua_State *L) {
luaL_checkstring(L, 1);
newemptycap(L, Cbackref, 1);
return 1;
}
/*
** Constant capture
*/
static int lp_constcapture (lua_State *L) {
int i;
int n = lua_gettop(L); /* number of values */
if (n == 0) /* no values? */
newleaf(L, TTrue); /* no capture */
else if (n == 1)
newemptycap(L, Cconst, 1); /* single constant capture */
else { /* create a group capture with all values */
TTree *tree = newtree(L, 1 + 3 * (n - 1) + 2);
tree->tag = TCapture;
tree->cap = Cgroup;
tree->key = 0;
tree = sib1(tree);
for (i = 1; i <= n - 1; i++) {
tree->tag = TSeq;
tree->u.ps = 3; /* skip TCapture and its sibling */
auxemptycap(L, sib1(tree), Cconst, i);
tree = sib2(tree);
}
auxemptycap(L, tree, Cconst, i);
}
return 1;
}
static int lp_matchtime (lua_State *L) {
TTree *tree;
luaL_checktype(L, 2, LUA_TFUNCTION);
tree = newroot1sib(L, TRunTime);
tree->key = addtoktable(L, 2);
return 1;
}
/* }====================================================== */
/*
** {======================================================
** Grammar - Tree generation
** =======================================================
*/
/*
** push on the stack the index and the pattern for the
** initial rule of grammar at index 'arg' in the stack;
** also add that index into position table.
*/
static void getfirstrule (lua_State *L, int arg, int postab) {
lua_rawgeti(L, arg, 1); /* access first element */
if (lua_isstring(L, -1)) { /* is it the name of initial rule? */
lua_pushvalue(L, -1); /* duplicate it to use as key */
lua_gettable(L, arg); /* get associated rule */
}
else {
lua_pushinteger(L, 1); /* key for initial rule */
lua_insert(L, -2); /* put it before rule */
}
if (!testpattern(L, -1)) { /* initial rule not a pattern? */
if (lua_isnil(L, -1))
luaL_error(L, "grammar has no initial rule");
else
luaL_error(L, "initial rule '%s' is not a pattern", lua_tostring(L, -2));
}
lua_pushvalue(L, -2); /* push key */
lua_pushinteger(L, 1); /* push rule position (after TGrammar) */
lua_settable(L, postab); /* insert pair at position table */
}
/*
** traverse grammar at index 'arg', pushing all its keys and patterns
** into the stack. Create a new table (before all pairs key-pattern) to
** collect all keys and their associated positions in the final tree
** (the "position table").
** Return the number of rules and (in 'totalsize') the total size
** for the new tree.
*/
static int collectrules (lua_State *L, int arg, int *totalsize) {
int n = 1; /* to count number of rules */
int postab = lua_gettop(L) + 1; /* index of position table */
int size; /* accumulator for total size */
lua_newtable(L); /* create position table */
getfirstrule(L, arg, postab);
size = 2 + getsize(L, postab + 2); /* TGrammar + TRule + rule */
lua_pushnil(L); /* prepare to traverse grammar table */
while (lua_next(L, arg) != 0) {
if (lua_tonumber(L, -2) == 1 ||
lua_equal(L, -2, postab + 1)) { /* initial rule? */
lua_pop(L, 1); /* remove value (keep key for lua_next) */
continue;
}
if (!testpattern(L, -1)) /* value is not a pattern? */
luaL_error(L, "rule '%s' is not a pattern", val2str(L, -2));
luaL_checkstack(L, LUA_MINSTACK, "grammar has too many rules");
lua_pushvalue(L, -2); /* push key (to insert into position table) */
lua_pushinteger(L, size);
lua_settable(L, postab);
size += 1 + getsize(L, -1); /* update size */
lua_pushvalue(L, -2); /* push key (for next lua_next) */
n++;
}
*totalsize = size + 1; /* TTrue to finish list of rules */
return n;
}
static void buildgrammar (lua_State *L, TTree *grammar, int frule, int n) {
int i;
TTree *nd = sib1(grammar); /* auxiliary pointer to traverse the tree */
for (i = 0; i < n; i++) { /* add each rule into new tree */
int ridx = frule + 2*i + 1; /* index of i-th rule */
int rulesize;
TTree *rn = gettree(L, ridx, &rulesize);
nd->tag = TRule;
nd->key = 0;
nd->cap = i; /* rule number */
nd->u.ps = rulesize + 1; /* point to next rule */
memcpy(sib1(nd), rn, rulesize * sizeof(TTree)); /* copy rule */
mergektable(L, ridx, sib1(nd)); /* merge its ktable into new one */
nd = sib2(nd); /* move to next rule */
}
nd->tag = TTrue; /* finish list of rules */
}
/*
** Check whether a tree has potential infinite loops
*/
static int checkloops (TTree *tree) {
tailcall:
if (tree->tag == TRep && nullable(sib1(tree)))
return 1;
else if (tree->tag == TGrammar)
return 0; /* sub-grammars already checked */
else {
switch (numsiblings[tree->tag]) {
case 1: /* return checkloops(sib1(tree)); */
tree = sib1(tree); goto tailcall;
case 2:
if (checkloops(sib1(tree))) return 1;
/* else return checkloops(sib2(tree)); */
tree = sib2(tree); goto tailcall;
default: assert(numsiblings[tree->tag] == 0); return 0;
}
}
}
static int verifyerror (lua_State *L, int *passed, int npassed) {
int i, j;
for (i = npassed - 1; i >= 0; i--) { /* search for a repetition */
for (j = i - 1; j >= 0; j--) {
if (passed[i] == passed[j]) {
lua_rawgeti(L, -1, passed[i]); /* get rule's key */
return luaL_error(L, "rule '%s' may be left recursive", val2str(L, -1));
}
}
}
return luaL_error(L, "too many left calls in grammar");
}
/*
** Check whether a rule can be left recursive; raise an error in that
** case; otherwise return 1 iff pattern is nullable. Assume ktable at
** the top of the stack.
*/
static int verifyrule (lua_State *L, TTree *tree, int *passed, int npassed,
int nullable) {
tailcall:
switch (tree->tag) {
case TChar: case TSet: case TAny:
case TFalse:
return nullable; /* cannot pass from here */
case TTrue:
case TBehind: /* look-behind cannot have calls */
return 1;
case TNot: case TAnd: case TRep:
/* return verifyrule(L, sib1(tree), passed, npassed, 1); */
tree = sib1(tree); nullable = 1; goto tailcall;
case TCapture: case TRunTime:
/* return verifyrule(L, sib1(tree), passed, npassed); */
tree = sib1(tree); goto tailcall;
case TCall:
/* return verifyrule(L, sib2(tree), passed, npassed); */
tree = sib2(tree); goto tailcall;
case TSeq: /* only check 2nd child if first is nullable */
if (!verifyrule(L, sib1(tree), passed, npassed, 0))
return nullable;
/* else return verifyrule(L, sib2(tree), passed, npassed); */
tree = sib2(tree); goto tailcall;
case TChoice: /* must check both children */
nullable = verifyrule(L, sib1(tree), passed, npassed, nullable);
/* return verifyrule(L, sib2(tree), passed, npassed, nullable); */
tree = sib2(tree); goto tailcall;
case TRule:
if (npassed >= MAXRULES)
return verifyerror(L, passed, npassed);
else {
passed[npassed++] = tree->key;
/* return verifyrule(L, sib1(tree), passed, npassed); */
tree = sib1(tree); goto tailcall;
}
case TGrammar:
return nullable(tree); /* sub-grammar cannot be left recursive */
default: assert(0); return 0;
}
}
static void verifygrammar (lua_State *L, TTree *grammar) {
int passed[MAXRULES];
TTree *rule;
/* check left-recursive rules */
for (rule = sib1(grammar); rule->tag == TRule; rule = sib2(rule)) {
if (rule->key == 0) continue; /* unused rule */
verifyrule(L, sib1(rule), passed, 0, 0);
}
assert(rule->tag == TTrue);
/* check infinite loops inside rules */
for (rule = sib1(grammar); rule->tag == TRule; rule = sib2(rule)) {
if (rule->key == 0) continue; /* unused rule */
if (checkloops(sib1(rule))) {
lua_rawgeti(L, -1, rule->key); /* get rule's key */
luaL_error(L, "empty loop in rule '%s'", val2str(L, -1));
}
}
assert(rule->tag == TTrue);
}
/*
** Give a name for the initial rule if it is not referenced
*/
static void initialrulename (lua_State *L, TTree *grammar, int frule) {
if (sib1(grammar)->key == 0) { /* initial rule is not referenced? */
int n = lua_objlen(L, -1) + 1; /* index for name */
lua_pushvalue(L, frule); /* rule's name */
lua_rawseti(L, -2, n); /* ktable was on the top of the stack */
sib1(grammar)->key = n;
}
}
static TTree *newgrammar (lua_State *L, int arg) {
int treesize;
int frule = lua_gettop(L) + 2; /* position of first rule's key */
int n = collectrules(L, arg, &treesize);
TTree *g = newtree(L, treesize);
luaL_argcheck(L, n <= MAXRULES, arg, "grammar has too many rules");
g->tag = TGrammar; g->u.n = n;
lua_newtable(L); /* create 'ktable' */
lua_setfenv(L, -2);
buildgrammar(L, g, frule, n);
lua_getfenv(L, -1); /* get 'ktable' for new tree */
finalfix(L, frule - 1, g, sib1(g));
initialrulename(L, g, frule);
verifygrammar(L, g);
lua_pop(L, 1); /* remove 'ktable' */
lua_insert(L, -(n * 2 + 2)); /* move new table to proper position */
lua_pop(L, n * 2 + 1); /* remove position table + rule pairs */
return g; /* new table at the top of the stack */
}
/* }====================================================== */
static Instruction *prepcompile (lua_State *L, Pattern *p, int idx) {
lua_getfenv(L, idx); /* push 'ktable' (may be used by 'finalfix') */
finalfix(L, 0, NULL, p->tree);
lua_pop(L, 1); /* remove 'ktable' */
return compile(L, p);
}
static int lp_printtree (lua_State *L) {
TTree *tree = getpatt(L, 1, NULL);
int c = lua_toboolean(L, 2);
if (c) {
lua_getfenv(L, 1); /* push 'ktable' (may be used by 'finalfix') */
finalfix(L, 0, NULL, tree);
lua_pop(L, 1); /* remove 'ktable' */
}
printktable(L, 1);
printtree(tree, 0);
return 0;
}
static int lp_printcode (lua_State *L) {
Pattern *p = getpattern(L, 1);
printktable(L, 1);
if (p->code == NULL) /* not compiled yet? */
prepcompile(L, p, 1);
printpatt(p->code, p->codesize);
return 0;
}
/*
** Get the initial position for the match, interpreting negative
** values from the end of the subject
*/
static size_t initposition (lua_State *L, size_t len) {
lua_Integer ii = luaL_optinteger(L, 3, 1);
if (ii > 0) { /* positive index? */
if ((size_t)ii <= len) /* inside the string? */
return (size_t)ii - 1; /* return it (corrected to 0-base) */
else return len; /* crop at the end */
}
else { /* negative index */
if ((size_t)(-ii) <= len) /* inside the string? */
return len - ((size_t)(-ii)); /* return position from the end */
else return 0; /* crop at the beginning */
}
}
/*
** Main match function
*/
static int lp_match (lua_State *L) {
Capture capture[INITCAPSIZE];
const char *r;
size_t l;
Pattern *p = (getpatt(L, 1, NULL), getpattern(L, 1));
Instruction *code = (p->code != NULL) ? p->code : prepcompile(L, p, 1);
const char *s = luaL_checklstring(L, SUBJIDX, &l);
size_t i = initposition(L, l);
int ptop = lua_gettop(L);
lua_pushnil(L); /* initialize subscache */
lua_pushlightuserdata(L, capture); /* initialize caplistidx */
lua_getfenv(L, 1); /* initialize penvidx */
r = match(L, s, s + i, s + l, code, capture, ptop);
if (r == NULL) {
lua_pushnil(L);
return 1;
}
return getcaptures(L, s, r, ptop);
}
/*
** {======================================================
** Library creation and functions not related to matching
** =======================================================
*/
static int lp_setmax (lua_State *L) {
luaL_optinteger(L, 1, -1);
lua_settop(L, 1);
lua_setfield(L, LUA_REGISTRYINDEX, MAXSTACKIDX);
return 0;
}
static int lp_version (lua_State *L) {
lua_pushstring(L, VERSION);
return 1;
}
static int lp_type (lua_State *L) {
if (testpattern(L, 1))
lua_pushliteral(L, "pattern");
else
lua_pushnil(L);
return 1;
}
int lp_gc (lua_State *L) {
Pattern *p = getpattern(L, 1);
if (p->codesize > 0)
reallocprog(L, p, 0);
return 0;
}
static void createcat (lua_State *L, const char *catname, int (catf) (int)) {
TTree *t = newcharset(L);
int i;
for (i = 0; i <= UCHAR_MAX; i++)
if (catf(i)) setchar(treebuffer(t), i);
lua_setfield(L, -2, catname);
}
static int lp_locale (lua_State *L) {
if (lua_isnoneornil(L, 1)) {
lua_settop(L, 0);
lua_createtable(L, 0, 12);
}
else {
luaL_checktype(L, 1, LUA_TTABLE);
lua_settop(L, 1);
}
createcat(L, "alnum", isalnum);
createcat(L, "alpha", isalpha);
createcat(L, "cntrl", iscntrl);
createcat(L, "digit", isdigit);
createcat(L, "graph", isgraph);
createcat(L, "lower", islower);
createcat(L, "print", isprint);
createcat(L, "punct", ispunct);
createcat(L, "space", isspace);
createcat(L, "upper", isupper);
createcat(L, "xdigit", isxdigit);
return 1;
}
static struct luaL_Reg pattreg[] = {
{"ptree", lp_printtree},
{"pcode", lp_printcode},
{"match", lp_match},
{"B", lp_behind},
{"V", lp_V},
{"C", lp_simplecapture},
{"Cc", lp_constcapture},
{"Cmt", lp_matchtime},
{"Cb", lp_backref},
{"Carg", lp_argcapture},
{"Cp", lp_poscapture},
{"Cs", lp_substcapture},
{"Ct", lp_tablecapture},
{"Cf", lp_foldcapture},
{"Cg", lp_groupcapture},
{"P", lp_P},
{"S", lp_set},
{"R", lp_range},
{"locale", lp_locale},
{"version", lp_version},
{"setmaxstack", lp_setmax},
{"type", lp_type},
{NULL, NULL}
};
static struct luaL_Reg metareg[] = {
{"__mul", lp_seq},
{"__add", lp_choice},
{"__pow", lp_star},
{"__gc", lp_gc},
{"__len", lp_and},
{"__div", lp_divcapture},
{"__unm", lp_not},
{"__sub", lp_sub},
{NULL, NULL}
};
int luaopen_lpeg (lua_State *L);
int luaopen_lpeg (lua_State *L) {
luaL_newmetatable(L, PATTERN_T);
lua_pushnumber(L, MAXBACK); /* initialize maximum backtracking */
lua_setfield(L, LUA_REGISTRYINDEX, MAXSTACKIDX);
luaL_register(L, NULL, metareg);
luaL_register(L, "lpeg", pattreg);
lua_pushvalue(L, -1);
lua_setfield(L, -3, "__index");
return 1;
}
/* }====================================================== */