Mercurial > hg > octave-lyh > gnulib-hg
changeset 3933:91cfbab32c36
(DISCARD_FAILURE_REG_OR_COUNT): Delete.
(CHECK_INFINITE_LOOP): Don't pop anything: just set `cycle' to 1.
(re_match_2_internal): Be more careful with infinite loops.
author | Stefan Monnier <monnier@iro.umontreal.ca> |
---|---|
date | Tue, 10 Sep 2002 05:59:32 +0000 |
parents | 9a7f7ab024aa |
children | aa1637221a20 |
files | regex.c |
diffstat | 1 files changed, 127 insertions(+), 132 deletions(-) [+] |
line wrap: on
line diff
--- a/regex.c +++ b/regex.c @@ -19,9 +19,7 @@ Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ -/* BUGS: - - (x?)*y\1z should match both xxxxyxz and xxxyz. - TODO: +/* TODO: - structure the opcode space into opcode+flag. - merge with glibc's regex.[ch]. - replace (succeed_n + jump_n + set_number_at) with something that doesn't @@ -1520,26 +1518,6 @@ } \ } while (0) -/* Discard a saved register off the stack. */ -#define DISCARD_FAILURE_REG_OR_COUNT() \ -do { \ - int reg = POP_FAILURE_INT (); \ - if (reg == -1) \ - { \ - /* It's a counter. */ \ - POP_FAILURE_POINTER (); \ - reg = POP_FAILURE_INT (); \ - DEBUG_PRINT3 (" Discard counter %p = %d\n", ptr, reg); \ - } \ - else \ - { \ - POP_FAILURE_POINTER (); \ - POP_FAILURE_POINTER (); \ - DEBUG_PRINT4 (" Discard reg %d (spanning %p -> %p)\n", \ - reg, regstart[reg], regend[reg]); \ - } \ -} while (0) - /* Check that we are not stuck in an infinite loop. */ #define CHECK_INFINITE_LOOP(pat_cur, string_place) \ do { \ @@ -1553,16 +1531,15 @@ && FAILURE_PAT (failure) <= bufp->buffer + bufp->used); \ if (FAILURE_PAT (failure) == pat_cur) \ { \ - while (fail_stack.frame < fail_stack.avail) \ - DISCARD_FAILURE_REG_OR_COUNT (); \ - goto fail; \ + cycle = 1; \ + break; \ } \ DEBUG_PRINT2 (" Other pattern: %p\n", FAILURE_PAT (failure)); \ failure = NEXT_FAILURE_HANDLE(failure); \ } \ DEBUG_PRINT2 (" Other string: %p\n", FAILURE_STR (failure)); \ } while (0) - + /* Push the information about the state we will need if we ever fail back to it. @@ -2645,8 +2622,8 @@ unsigned int startoffset = 0; re_opcode_t ofj = /* Check if the loop can match the empty string. */ - (simple || !analyse_first (laststart, b, NULL, 0)) ? - on_failure_jump : on_failure_jump_loop; + (simple || !analyse_first (laststart, b, NULL, 0)) + ? on_failure_jump : on_failure_jump_loop; assert (skip_one_char (laststart) <= b); if (!zero_times_ok && simple) @@ -2694,8 +2671,9 @@ { boolean emptyp = analyse_first (laststart, b, NULL, 0); - /* The non-greedy multiple match looks like a repeat..until: - we only need a conditional jump at the end of the loop */ + /* The non-greedy multiple match looks like + a repeat..until: we only need a conditional jump + at the end of the loop. */ if (emptyp) BUF_PUSH (no_op); STORE_JUMP (emptyp ? on_failure_jump_nastyloop : on_failure_jump, b, laststart); @@ -2704,7 +2682,7 @@ { /* The repeat...until naturally matches one or more. To also match zero times, we need to first jump to - the end of the loop (its conditional jump). */ + the end of the loop (its conditional jump). */ INSERT_JUMP (jump, laststart, b); b += 3; } @@ -3241,99 +3219,99 @@ goto unfetch_interval; } - if (upper_bound == 0) - /* If the upper bound is zero, just drop the sub pattern - altogether. */ - b = laststart; - else if (lower_bound == 1 && upper_bound == 1) - /* Just match it once: nothing to do here. */ - ; - - /* Otherwise, we have a nontrivial interval. When - we're all done, the pattern will look like: - set_number_at <jump count> <upper bound> - set_number_at <succeed_n count> <lower bound> - succeed_n <after jump addr> <succeed_n count> - <body of loop> - jump_n <succeed_n addr> <jump count> - (The upper bound and `jump_n' are omitted if - `upper_bound' is 1, though.) */ - else - { /* If the upper bound is > 1, we need to insert - more at the end of the loop. */ - unsigned int nbytes = (upper_bound < 0 ? 3 - : upper_bound > 1 ? 5 : 0); - unsigned int startoffset = 0; - - GET_BUFFER_SPACE (20); /* We might use less. */ - - if (lower_bound == 0) - { - /* A succeed_n that starts with 0 is really a - a simple on_failure_jump_loop. */ - INSERT_JUMP (on_failure_jump_loop, laststart, - b + 3 + nbytes); - b += 3; - } - else - { - /* Initialize lower bound of the `succeed_n', even - though it will be set during matching by its - attendant `set_number_at' (inserted next), - because `re_compile_fastmap' needs to know. - Jump to the `jump_n' we might insert below. */ - INSERT_JUMP2 (succeed_n, laststart, - b + 5 + nbytes, - lower_bound); - b += 5; - - /* Code to initialize the lower bound. Insert - before the `succeed_n'. The `5' is the last two - bytes of this `set_number_at', plus 3 bytes of - the following `succeed_n'. */ - insert_op2 (set_number_at, laststart, 5, lower_bound, b); - b += 5; - startoffset += 5; - } - - if (upper_bound < 0) - { - /* A negative upper bound stands for infinity, - in which case it degenerates to a plain jump. */ - STORE_JUMP (jump, b, laststart + startoffset); - b += 3; - } - else if (upper_bound > 1) - { /* More than one repetition is allowed, so - append a backward jump to the `succeed_n' - that starts this interval. - - When we've reached this during matching, - we'll have matched the interval once, so - jump back only `upper_bound - 1' times. */ - STORE_JUMP2 (jump_n, b, laststart + startoffset, - upper_bound - 1); - b += 5; - - /* The location we want to set is the second - parameter of the `jump_n'; that is `b-2' as - an absolute address. `laststart' will be - the `set_number_at' we're about to insert; - `laststart+3' the number to set, the source - for the relative address. But we are - inserting into the middle of the pattern -- - so everything is getting moved up by 5. - Conclusion: (b - 2) - (laststart + 3) + 5, - i.e., b - laststart. - - We insert this at the beginning of the loop - so that if we fail during matching, we'll - reinitialize the bounds. */ - insert_op2 (set_number_at, laststart, b - laststart, - upper_bound - 1, b); - b += 5; - } - } + if (upper_bound == 0) + /* If the upper bound is zero, just drop the sub pattern + altogether. */ + b = laststart; + else if (lower_bound == 1 && upper_bound == 1) + /* Just match it once: nothing to do here. */ + ; + + /* Otherwise, we have a nontrivial interval. When + we're all done, the pattern will look like: + set_number_at <jump count> <upper bound> + set_number_at <succeed_n count> <lower bound> + succeed_n <after jump addr> <succeed_n count> + <body of loop> + jump_n <succeed_n addr> <jump count> + (The upper bound and `jump_n' are omitted if + `upper_bound' is 1, though.) */ + else + { /* If the upper bound is > 1, we need to insert + more at the end of the loop. */ + unsigned int nbytes = (upper_bound < 0 ? 3 + : upper_bound > 1 ? 5 : 0); + unsigned int startoffset = 0; + + GET_BUFFER_SPACE (20); /* We might use less. */ + + if (lower_bound == 0) + { + /* A succeed_n that starts with 0 is really a + a simple on_failure_jump_loop. */ + INSERT_JUMP (on_failure_jump_loop, laststart, + b + 3 + nbytes); + b += 3; + } + else + { + /* Initialize lower bound of the `succeed_n', even + though it will be set during matching by its + attendant `set_number_at' (inserted next), + because `re_compile_fastmap' needs to know. + Jump to the `jump_n' we might insert below. */ + INSERT_JUMP2 (succeed_n, laststart, + b + 5 + nbytes, + lower_bound); + b += 5; + + /* Code to initialize the lower bound. Insert + before the `succeed_n'. The `5' is the last two + bytes of this `set_number_at', plus 3 bytes of + the following `succeed_n'. */ + insert_op2 (set_number_at, laststart, 5, lower_bound, b); + b += 5; + startoffset += 5; + } + + if (upper_bound < 0) + { + /* A negative upper bound stands for infinity, + in which case it degenerates to a plain jump. */ + STORE_JUMP (jump, b, laststart + startoffset); + b += 3; + } + else if (upper_bound > 1) + { /* More than one repetition is allowed, so + append a backward jump to the `succeed_n' + that starts this interval. + + When we've reached this during matching, + we'll have matched the interval once, so + jump back only `upper_bound - 1' times. */ + STORE_JUMP2 (jump_n, b, laststart + startoffset, + upper_bound - 1); + b += 5; + + /* The location we want to set is the second + parameter of the `jump_n'; that is `b-2' as + an absolute address. `laststart' will be + the `set_number_at' we're about to insert; + `laststart+3' the number to set, the source + for the relative address. But we are + inserting into the middle of the pattern -- + so everything is getting moved up by 5. + Conclusion: (b - 2) - (laststart + 3) + 5, + i.e., b - laststart. + + We insert this at the beginning of the loop + so that if we fail during matching, we'll + reinitialize the bounds. */ + insert_op2 (set_number_at, laststart, b - laststart, + upper_bound - 1, b); + b += 5; + } + } pending_exact = 0; beg_interval = NULL; } @@ -5518,7 +5496,7 @@ cycle detection cannot work. Worse yet, such a detection can not only fail to detect a cycle, but it can also wrongly detect a cycle (between different instantiations of the same - loop. + loop). So the method used for those nasty loops is a little different: We use a special cycle-detection-stack-frame which is pushed when the on_failure_jump_nastyloop failure-point is *popped*. @@ -5532,11 +5510,18 @@ mcnt, p + mcnt); assert ((re_opcode_t)p[-4] == no_op); - CHECK_INFINITE_LOOP (p - 4, d); - PUSH_FAILURE_POINT (p - 3, d); + { + int cycle = 0; + CHECK_INFINITE_LOOP (p - 4, d); + if (!cycle) + /* If there's a cycle, just continue without pushing + this failure point. The failure point is the "try again" + option, which shouldn't be tried. + We want (x?)*?y\1z to match both xxyz and xxyxz. */ + PUSH_FAILURE_POINT (p - 3, d); + } break; - /* Simple loop detecting on_failure_jump: just check on the failure stack if the same spot was already hit earlier. */ case on_failure_jump_loop: @@ -5544,9 +5529,19 @@ EXTRACT_NUMBER_AND_INCR (mcnt, p); DEBUG_PRINT3 ("EXECUTING on_failure_jump_loop %d (to %p):\n", mcnt, p + mcnt); - - CHECK_INFINITE_LOOP (p - 3, d); - PUSH_FAILURE_POINT (p - 3, d); + { + int cycle = 0; + CHECK_INFINITE_LOOP (p - 3, d); + if (cycle) + /* If there's a cycle, get out of the loop, as if the matching + had failed. We used to just `goto fail' here, but that was + aborting the search a bit too early: we want to keep the + empty-loop-match and keep matching after the loop. + We want (x?)*y\1z to match both xxyz and xxyxz. */ + p += mcnt; + else + PUSH_FAILURE_POINT (p - 3, d); + } break;