1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767
|
// -*- C++ -*-
// Copyright (C) 2012-2013 Red Hat Inc.
//
// This file is part of systemtap, and is free software. You can
// redistribute it and/or modify it under the terms of the GNU General
// Public License (GPL); either version 2, or (at your option) any
// later version.
//
// ---
//
// This file incorporates code from the re2c project; please see
// the file README.stapregex for details.
#include <string>
#include <iostream>
#include <sstream>
#include <set>
#include <list>
#include <map>
#include <vector>
#include <queue>
#include <utility>
#include "translator-output.h"
#include "stapregex-parse.h"
#include "stapregex-tree.h"
#include "stapregex-dfa.h"
// Uncomment to show result of ins (NFA) compilation:
//#define STAPREGEX_DEBUG_INS
// Uncomment to display result of DFA compilation in a compact format:
//#define STAPREGEX_DEBUG_DFA
// Uncomment to have the generated engine do a trace of visited states:
//#define STAPREGEX_DEBUG_MATCH
using namespace std;
namespace stapregex {
regexp *pad_re = NULL;
regexp *fail_re = NULL;
dfa *
stapregex_compile (regexp *re, const std::string& match_snippet,
const std::string& fail_snippet)
{
if (pad_re == NULL) {
// build regexp for ".*"
pad_re = make_dot ();
pad_re = new close_op (pad_re, true); // -- prefer shorter match
pad_re = new alt_op (pad_re, new null_op, true); // -- prefer second match
}
if (fail_re == NULL) {
// build regexp for ".*$", but allow '\0' and support fail outcome
fail_re = make_dot (true); // -- allow '\0'
fail_re = new close_op (fail_re, true); // -- prefer shorter match
fail_re = new alt_op (fail_re, new null_op, true); // -- prefer second match
fail_re = new cat_op (fail_re, new anchor_op('$'));
fail_re = new rule_op(fail_re, 0);
// XXX: this approach creates one extra spurious-but-safe state
// (safe because the matching procedure stops after encountering '\0')
}
vector<string> outcomes(2);
outcomes[0] = fail_snippet;
outcomes[1] = match_snippet;
int num_tags = re->num_tags;
// Pad & wrap re in appropriate rule_ops to control match behaviour:
bool anchored = re->anchored ();
if (!anchored) re = new cat_op(pad_re, re); // -- left-padding
re = new rule_op(re, 1);
re = new alt_op(re, fail_re);
#ifdef STAPREGEX_DEBUG_INS
cerr << "RESULTING INS FROM REGEX " << re << ":" << endl;
#endif
ins *i = re->compile();
#ifdef STAPREGEX_DEBUG_INS
for (const ins *j = i; (j - i) < re->ins_size() + 1; )
{
j = show_ins(cerr, j, i); cerr << endl;
}
cerr << endl;
#endif
// TODOXXX optimize ins as in re2c
dfa *d = new dfa(i, num_tags, outcomes);
// Carefully deallocate temporary scaffolding:
if (!anchored) delete ((rule_op*) ((alt_op*) re)->a)->re; // -- new cat_op
delete ((alt_op*) re)->a; // -- new rule_op
delete re; // -- new alt_op
// NB: deleting a regular expression DOES NOT deallocate its
// children. The original re parameter is presumed to be retained
// indefinitely as part of a stapdfa table, or such....
return d;
}
// ------------------------------------------------------------------------
/* Now follows the heart of the tagged-DFA algorithm. This is a basic
implementation of the algorithm described in Ville Laurikari's
Masters thesis and summarized in the paper "NFAs with Tagged
Transitions, their Conversion to Deterministic Automata and
Application to Regular Expressions"
(http://laurikari.net/ville/spire2000-tnfa.pdf).
TODOXXX: The following does not contain a fully working
implementation of the tagging support, but only of the regex
matching.
HERE BE DRAGONS (and not the friendly kind) */
/* Functions to deal with relative transition priorities: */
arc_priority
refine_higher(const arc_priority& a)
{
return make_pair(2 * a.first + 1, a.second + 1);
}
arc_priority
refine_lower (const arc_priority& a)
{
return make_pair(2 * a.first, a.second + 1);
}
int
arc_compare (const arc_priority& a, const arc_priority& b)
{
unsigned long x = a.first;
unsigned long y = b.first;
if (a.second > b.second)
x = x << (a.second - b.second);
else if (a.second < b.second)
y = y << (b.second - a.second);
return ( x == y ? 0 : x < y ? -1 : 1 );
}
/* Manage the linked list of states in a DFA: */
state::state (state_kernel *kernel)
: label(~0), next(NULL), kernel(kernel), accepts(false), accept_outcome(0) {}
state *
dfa::add_state (state *s)
{
s->label = nstates++;
if (last == NULL)
{
last = s;
first = last;
}
else
{
// append to the end
last->next = s;
last = last->next;
}
return last;
}
/* Operations to build a simple kernel prior to taking closure: */
void
add_kernel (state_kernel *kernel, ins *i)
{
kernel_point point;
point.i = i;
point.priority = make_pair(0,0);
// NB: point->map_items is empty
kernel->push_back(point);
}
state_kernel *
make_kernel (ins *i)
{
state_kernel *kernel = new state_kernel;
add_kernel (kernel, i);
return kernel;
}
/* Compute the set of kernel_points that are 'tag-wise unambiguously
reachable' from a given initial set of points. Absent tagging, this
becomes a bog-standard NFA e_closure construction. */
state_kernel *
te_closure (state_kernel *start, int ntags, bool is_initial = false)
{
state_kernel *closure = new state_kernel(*start);
queue<kernel_point> worklist;
/* To avoid searching through closure incessantly when retrieving
information about existing elements, the following caches are
needed: */
vector<unsigned> max_tags (ntags, 0);
map<ins *, list<kernel_point> > closure_map;
/* Reset priorities and cache initial elements of closure: */
for (state_kernel::iterator it = closure->begin();
it != closure->end(); it++)
{
it->priority = make_pair(0,0);
worklist.push(*it);
// Store the element in relevant caches:
for (list<map_item>::const_iterator jt = it->map_items.begin();
jt != it->map_items.end(); jt++)
max_tags[jt->first] = max(jt->second, max_tags[jt->first]);
closure_map[it->i].push_back(*it);
}
while (!worklist.empty())
{
kernel_point point = worklist.front(); worklist.pop();
// Identify e-transitions depending on the opcode.
// There are at most two e-transitions emerging from an insn.
// If we have two e-transitions, the 'other' has higher priority.
ins *target = NULL; int tag = -1;
ins *other_target = NULL; int other_tag = -1;
// TODOXXX line-by-line proceeds below
bool do_split = false;
if (point.i->i.tag == TAG)
{
target = &point.i[1];
tag = (int) point.i->i.param;
}
else if (point.i->i.tag == FORK && point.i == (ins *) point.i->i.link)
{
/* Workaround for a FORK that points to itself: */
target = &point.i[1];
}
else if (point.i->i.tag == FORK)
{
do_split = true;
// Relative priority of two e-transitions depends on param:
if (point.i->i.param)
{
// Prefer jumping to link.
target = &point.i[1];
other_target = (ins *) point.i->i.link;
}
else
{
// Prefer stepping to next instruction.
target = (ins *) point.i->i.link;
other_target = &point.i[1];
}
}
else if (point.i->i.tag == GOTO)
{
target = (ins *) point.i->i.link;
}
else if (point.i->i.tag == INIT && is_initial)
{
target = &point.i[1];
}
bool already_found;
// Data for the endpoint of the first transition:
kernel_point next;
next.i = target;
next.priority = do_split ? refine_lower(point.priority) : point.priority;
next.map_items = point.map_items;
// Date for the endpoint of the second transition:
kernel_point other_next;
other_next.i = other_target;
other_next.priority = do_split ? refine_higher(point.priority) : point.priority;
other_next.map_items = point.map_items;
// Do infinite-loop-check:
other_next.parents = point.parents;
if (point.parents.find(other_next.i) != point.parents.end())
{
other_target = NULL;
other_tag = -1;
}
other_next.parents.insert(other_next.i);
next.parents = point.parents;
if (point.parents.find(next.i) != point.parents.end())
{
// target = NULL;
// tag = -1;
// ^^^ these are overwritten from other_target / other_tag immediately
goto next_target;
}
next.parents.insert(next.i);
another_transition:
if (target == NULL)
continue;
// Deal with the current e-transition:
if (tag >= 0)
{
/* Delete all existing next.map_items of the form m[tag,x]. */
for (list<map_item>::iterator it = next.map_items.begin();
it != next.map_items.end(); )
if (it->first == (unsigned) tag)
{
list<map_item>::iterator next_it = it;
next_it++;
next.map_items.erase (it);
it = next_it;
}
else it++;
/* Add m[tag,x] to next.map_items, where x is the smallest
nonnegative integer such that m[tag,x] does not occur
anywhere in closure. Then update the cache. */
unsigned x = max_tags[tag];
next.map_items.push_back(make_pair(tag, ++x));
max_tags[tag] = x;
}
already_found = false;
/* Deal with similar transitions that have a different priority. */
for (list<kernel_point>::iterator it = closure_map[next.i].begin();
it != closure_map[next.i].end(); )
{
int result = arc_compare(it->priority, next.priority);
if (result > 0) {
// obnoxious shuffle to avoid iterator invalidation
list<kernel_point>::iterator old_it = it;
it++;
closure_map[next.i].erase(old_it);
continue;
} else if (result == 0) {
already_found = true;
}
it++;
}
if (!already_found) {
// Store the element in relevant caches:
closure_map[next.i].push_back(next);
for (list<map_item>::iterator jt = next.map_items.begin();
jt != next.map_items.end(); jt++)
max_tags[jt->first] = max(jt->second, max_tags[jt->first]);
// Store the element in closure:
closure->push_back(next);
worklist.push(next);
}
next_target:
// Now move to dealing with the second e-transition, if any.
target = other_target; other_target = NULL;
tag = other_tag; other_tag = -1;
next = other_next;
goto another_transition;
}
return closure;
}
/* Find the set of reordering commands (if any) that will get us from
state s to some existing state in the dfa (returns the state in
question, appends reordering commands to r). Returns NULL is no
suitable state is found. */
state *
dfa::find_equivalent (state *s, tdfa_action &)
{
state *answer = NULL;
for (state_kernel::iterator it = s->kernel->begin();
it != s->kernel->end(); it++)
mark(it->i);
/* Check kernels of existing states for size equivalence and for
unmarked items (similar to re2c's original algorithm): */
unsigned n = s->kernel->size();
for (state *t = first; t != NULL; t = t->next)
{
if (t->kernel->size() == n)
{
for (state_kernel::iterator it = t->kernel->begin();
it != t->kernel->end(); it++)
if (!marked(it->i))
goto next_state;
// TODOXXX check for existence of reordering tdfa_action r
answer = t;
goto cleanup;
}
next_state:
;
}
cleanup:
for (state_kernel::iterator it = s->kernel->begin();
it != s->kernel->end(); it++)
unmark(it->i);
return answer;
}
dfa::dfa (ins *i, int ntags, vector<string>& outcome_snippets)
: orig_nfa(i), nstates(0), ntags(ntags), outcome_snippets(outcome_snippets)
{
/* Initialize empty linked list of states: */
first = last = NULL;
ins *start = &i[0];
state_kernel *seed_kernel = make_kernel(start);
state_kernel *initial_kernel = te_closure(seed_kernel, ntags, true);
delete seed_kernel;
state *initial = add_state(new state(initial_kernel));
queue<state *> worklist; worklist.push(initial);
while (!worklist.empty())
{
state *curr = worklist.front(); worklist.pop();
vector<list<ins *> > edges(NUM_REAL_CHARS);
/* Using the CHAR instructions in kernel, build the initial
table of spans for curr. Also check for final states. */
for (list<kernel_point>::iterator it = curr->kernel->begin();
it != curr->kernel->end(); it++)
{
if (it->i->i.tag == CHAR)
{
for (ins *j = &it->i[1]; j < (ins *) it->i->i.link; j++)
edges[j->c.value].push_back((ins *) it->i->i.link);
}
else if (it->i->i.tag == ACCEPT)
{
/* Always prefer the highest numbered outcome: */
curr->accepts = true;
curr->accept_outcome = max(it->i->i.param, curr->accept_outcome);
}
}
for (unsigned c = 0; c < NUM_REAL_CHARS; )
{
list <ins *> e = edges[c];
assert (!e.empty()); // XXX: ensured by fail_re in stapregex_compile
span s;
s.lb = c;
while (++c < NUM_REAL_CHARS && edges[c] == e) ;
s.ub = c - 1;
s.reach_pairs = new state_kernel;
for (list<ins *>::iterator it = e.begin();
it != e.end(); it++)
add_kernel (s.reach_pairs, *it);
curr->spans.push_back(s);
}
/* For each of the spans in curr, determine the reachable
points assuming a character in the span. */
for (list<span>::iterator it = curr->spans.begin();
it != curr->spans.end(); it++)
{
state_kernel *reach_pairs = it->reach_pairs;
/* Set up candidate target state: */
state_kernel *u_pairs = te_closure(reach_pairs, ntags);
state *target = new state(u_pairs);
tdfa_action c;
/* Generate position-save commands for any map items
that do not appear in curr->kernel: */
set<map_item> all_items;
for (state_kernel::const_iterator jt = curr->kernel->begin();
jt != curr->kernel->end(); jt++)
for (list<map_item>::const_iterator kt = jt->map_items.begin();
kt != jt->map_items.end(); jt++)
all_items.insert(*kt);
list<map_item> store_items;
for (state_kernel::const_iterator jt = u_pairs->begin();
jt != u_pairs->end(); jt++)
for (list<map_item>::const_iterator kt = jt->map_items.begin();
kt != jt->map_items.end(); kt++)
if (all_items.find(*kt) == all_items.end())
store_items.push_back(*kt);
for (list<map_item>::iterator jt = store_items.begin();
jt != store_items.end(); jt++)
{
// append m[i,n] <- <curr position> to c
tdfa_insn insn;
insn.to = *jt;
insn.save_pos = true;
c.push_back(insn);
}
/* If there is a state t_prime in states such that some
sequence of reordering commands r produces t_prime
from target, use t_prime as the target state,
appending the reordering commands to c. */
state *t_prime = find_equivalent(target, c);
if (t_prime != NULL)
{
delete target;
}
else
{
/* We need to actually add target to the dfa: */
t_prime = target;
add_state(t_prime);
worklist.push(t_prime);
if (t_prime->accepts)
{
// TODOXXX set the finisher of t_prime
}
}
/* Set the transition: */
it->to = t_prime;
it->action = c;
}
}
}
dfa::~dfa ()
{
state * s;
while ((s = first))
{
first = s->next;
delete s;
}
delete orig_nfa;
}
// ------------------------------------------------------------------------
// TODOXXX add emission instructions for tag_ops
void
span::emit_jump (translator_output *o, const dfa *d) const
{
#ifdef STAPREGEX_DEBUG_MATCH
o->newline () << "printf(\" --> GOTO yystate%d\\n\", " << to->label << ");";
#endif
// TODOXXX tags feature allows proper longest-match priority
if (to->accepts)
{
emit_final(o, d);
}
else
{
o->newline () << "YYCURSOR++;";
o->newline () << "goto yystate" << to->label << ";";
}
}
/* Assuming the target DFA of the span is a final state, emit code to
(TODOXXX) cleanup tags and exit with a final answer. */
void
span::emit_final (translator_output *o, const dfa *d) const
{
assert (to->accepts); // XXX: must guarantee correct usage of emit_final()
o->newline() << d->outcome_snippets[to->accept_outcome];
o->newline() << "goto yyfinish;";
}
string c_char(char c)
{
stringstream o;
o << "'";
print_escaped(o, c);
o << "'";
return o.str();
}
void
state::emit (translator_output *o, const dfa *d) const
{
o->newline() << "yystate" << label << ": ";
#ifdef STAPREGEX_DEBUG_MATCH
o->newline () << "printf(\"READ '%s' %c\", cur, *YYCURSOR);";
#endif
o->newline() << "switch (*YYCURSOR) {";
o->indent(1);
for (list<span>::const_iterator it = spans.begin();
it != spans.end(); it++)
{
// If we see a '\0', go immediately into an accept state:
if (it->lb == '\0')
{
o->newline() << "case " << c_char('\0') << ":";
it->emit_final(o, d); // TODOXXX extra function may be unneeded
}
// Emit labels to handle all the other elements of the span:
for (unsigned c = max('\1', it->lb); c <= (unsigned) it->ub; c++) {
o->newline() << "case " << c_char((char) c) << ":";
}
it->emit_jump(o, d);
// TODOXXX handle a 'default' set of characters for the largest span...
// TODOXXX optimize by accepting before end of string whenever possible... (also necessary for proper first-matched-substring selection)
}
o->newline(-1) << "}";
}
void
dfa::emit (translator_output *o) const
{
#ifdef STAPREGEX_DEBUG_DFA
print(o);
#else
o->newline() << "{";
o->newline(1);
// XXX: workaround for empty regex
if (first->accepts)
{
o->newline() << outcome_snippets[first->accept_outcome];
o->newline() << "goto yyfinish;";
}
for (state *s = first; s; s = s->next)
s->emit(o, this);
o->newline() << "yyfinish: ;";
o->newline(-1) << "}";
#endif
}
void
dfa::emit_tagsave (translator_output *, std::string,
std::string, std::string) const
{
// TODOXXX implement after testing the preceding algorithms
}
// ------------------------------------------------------------------------
std::ostream&
operator << (std::ostream &o, const tdfa_action& a)
{
for (list<tdfa_insn>::const_iterator it = a.begin();
it != a.end(); it++)
{
if (it != a.begin()) o << "; ";
o << "m[" << it->to.first << "," << it->to.second << "] <- ";
if (it->save_pos)
o << "p";
else
o << "m[" << it->from.first << "," << it->from.second << "]";
}
return o;
}
std::ostream&
operator << (std::ostream &o, const arc_priority& p)
{
o << p.first << "/" << (1 << p.second);
return o;
}
void
state::print (translator_output *o) const
{
o->line() << "state " << label;
if (accepts)
o->line() << " accepts " << accept_outcome;
if (!finalizer.empty())
o->line() << " [" << finalizer << "]";
o->indent(1);
for (list<span>::const_iterator it = spans.begin();
it != spans.end(); it++)
{
o->newline() << "'";
if (it->lb == it->ub)
{
print_escaped (o->line(), it->lb);
o->line() << " ";
}
else
{
print_escaped (o->line(), it->lb);
o->line() << "-";
print_escaped (o->line(), it->ub);
}
o->line() << "' -> " << it->to->label;
if (!it->action.empty())
o->line() << " [" << it->action << "]";
}
o->newline(-1);
}
void
dfa::print (std::ostream& o) const
{
translator_output to(o); print(&to);
}
void
dfa::print (translator_output *o) const
{
o->newline();
for (state *s = first; s; s = s->next)
{
s->print(o);
o->newline();
}
o->newline();
}
std::ostream&
operator << (std::ostream& o, const dfa& d)
{
d.print(o);
return o;
}
std::ostream&
operator << (std::ostream &o, const dfa *d)
{
o << *d;
return o;
}
};
/* vim: set sw=2 ts=8 cino=>4,n-2,{2,^-2,t0,(0,u0,w1,M1 : */
|