diff options
Diffstat (limited to 'lib/Support/regcomp.c')
| -rw-r--r-- | lib/Support/regcomp.c | 30 |
1 files changed, 29 insertions, 1 deletions
diff --git a/lib/Support/regcomp.c b/lib/Support/regcomp.c index 46c91a9..74d9186 100644 --- a/lib/Support/regcomp.c +++ b/lib/Support/regcomp.c @@ -303,6 +303,7 @@ p_ere_exp(struct parse *p) sopno pos; int count; int count2; + int backrefnum; sopno subno; int wascaret = 0; @@ -370,7 +371,34 @@ p_ere_exp(struct parse *p) case '\\': REQUIRE(MORE(), REG_EESCAPE); c = GETNEXT(); - ordinary(p, c); + if (c >= '1' && c <= '9') { + /* \[0-9] is taken to be a back-reference to a previously specified + * matching group. backrefnum will hold the number. The matching + * group must exist (i.e. if \4 is found there must have been at + * least 4 matching groups specified in the pattern previously). + */ + backrefnum = c - '0'; + if (p->pend[backrefnum] == 0) { + SETERROR(REG_ESUBREG); + break; + } + + /* Make sure everything checks out and emit the sequence + * that marks a back-reference to the parse structure. + */ + assert(backrefnum <= p->g->nsub); + EMIT(OBACK_, backrefnum); + assert(p->pbegin[backrefnum] != 0); + assert(OP(p->strip[p->pbegin[backrefnum]]) != OLPAREN); + assert(OP(p->strip[p->pend[backrefnum]]) != ORPAREN); + (void) dupl(p, p->pbegin[backrefnum]+1, p->pend[backrefnum]); + EMIT(O_BACK, backrefnum); + p->g->backrefs = 1; + } else { + /* Other chars are simply themselves when escaped with a backslash. + */ + ordinary(p, c); + } break; case '{': /* okay as ordinary except if digit follows */ REQUIRE(!MORE() || !isdigit((uch)PEEK()), REG_BADRPT); |