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Diffstat (limited to 'dfa.c')
| -rw-r--r-- | dfa.c | 2309 |
1 files changed, 2309 insertions, 0 deletions
@@ -0,0 +1,2309 @@ +/* dfa.c - determinisitic extended regexp routines for GNU + Copyright (C) 1988 Free Software Foundation, Inc. + Written June, 1988 by Mike Haertel + Modified July, 1988 by Arthur David Olson + to assist BMG speedups + + NO WARRANTY + + BECAUSE THIS PROGRAM IS LICENSED FREE OF CHARGE, WE PROVIDE ABSOLUTELY +NO WARRANTY, TO THE EXTENT PERMITTED BY APPLICABLE STATE LAW. EXCEPT +WHEN OTHERWISE STATED IN WRITING, FREE SOFTWARE FOUNDATION, INC, +RICHARD M. STALLMAN AND/OR OTHER PARTIES PROVIDE THIS PROGRAM "AS IS" +WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, +BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND +FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY +AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE +DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR +CORRECTION. + + IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW WILL RICHARD M. +STALLMAN, THE FREE SOFTWARE FOUNDATION, INC., AND/OR ANY OTHER PARTY +WHO MAY MODIFY AND REDISTRIBUTE THIS PROGRAM AS PERMITTED BELOW, BE +LIABLE TO YOU FOR DAMAGES, INCLUDING ANY LOST PROFITS, LOST MONIES, OR +OTHER SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE +USE OR INABILITY TO USE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR +DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY THIRD PARTIES OR +A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS) THIS +PROGRAM, EVEN IF YOU HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH +DAMAGES, OR FOR ANY CLAIM BY ANY OTHER PARTY. + + GENERAL PUBLIC LICENSE TO COPY + + 1. You may copy and distribute verbatim copies of this source file +as you receive it, in any medium, provided that you conspicuously and +appropriately publish on each copy a valid copyright notice "Copyright + (C) 1988 Free Software Foundation, Inc."; and include following the +copyright notice a verbatim copy of the above disclaimer of warranty +and of this License. You may charge a distribution fee for the +physical act of transferring a copy. + + 2. You may modify your copy or copies of this source file or +any portion of it, and copy and distribute such modifications under +the terms of Paragraph 1 above, provided that you also do the following: + + a) cause the modified files to carry prominent notices stating + that you changed the files and the date of any change; and + + b) cause the whole of any work that you distribute or publish, + that in whole or in part contains or is a derivative of this + program or any part thereof, to be licensed at no charge to all + third parties on terms identical to those contained in this + License Agreement (except that you may choose to grant more extensive + warranty protection to some or all third parties, at your option). + + c) You may charge a distribution fee for the physical act of + transferring a copy, and you may at your option offer warranty + protection in exchange for a fee. + +Mere aggregation of another unrelated program with this program (or its +derivative) on a volume of a storage or distribution medium does not bring +the other program under the scope of these terms. + + 3. You may copy and distribute this program or any portion of it in +compiled, executable or object code form under the terms of Paragraphs +1 and 2 above provided that you do the following: + + a) accompany it with the complete corresponding machine-readable + source code, which must be distributed under the terms of + Paragraphs 1 and 2 above; or, + + b) accompany it with a written offer, valid for at least three + years, to give any third party free (except for a nominal + shipping charge) a complete machine-readable copy of the + corresponding source code, to be distributed under the terms of + Paragraphs 1 and 2 above; or, + + c) accompany it with the information you received as to where the + corresponding source code may be obtained. (This alternative is + allowed only for noncommercial distribution and only if you + received the program in object code or executable form alone.) + +For an executable file, complete source code means all the source code for +all modules it contains; but, as a special exception, it need not include +source code for modules which are standard libraries that accompany the +operating system on which the executable file runs. + + 4. You may not copy, sublicense, distribute or transfer this program +except as expressly provided under this License Agreement. Any attempt +otherwise to copy, sublicense, distribute or transfer this program is void and +your rights to use the program under this License agreement shall be +automatically terminated. However, parties who have received computer +software programs from you with this License Agreement will not have +their licenses terminated so long as such parties remain in full compliance. + + 5. If you wish to incorporate parts of this program into other free +programs whose distribution conditions are different, write to the Free +Software Foundation at 675 Mass Ave, Cambridge, MA 02139. We have not yet +worked out a simple rule that can be stated here, but we will often permit +this. We will be guided by the two goals of preserving the free status of +all derivatives our free software and of promoting the sharing and reuse of +software. + + +In other words, you are welcome to use, share and improve this program. +You are forbidden to forbid anyone else to use, share and improve +what you give them. Help stamp out software-hoarding! */ + +#include "awk.h" +#include <assert.h> + +#ifdef setbit /* surprise - setbit and clrbit are macros on NeXT */ +#undef setbit +#endif +#ifdef clrbit +#undef clrbit +#endif + +#ifdef __STDC__ +typedef void *ptr_t; +#else +typedef char *ptr_t; +#endif + +typedef struct { + char ** in; + char * left; + char * right; + char * is; +} must; + +static ptr_t xcalloc P((int n, size_t s)); +static ptr_t xmalloc P((size_t n)); +static ptr_t xrealloc P((ptr_t p, size_t n)); +static int tstbit P((int b, _charset c)); +static void setbit P((int b, _charset c)); +static void clrbit P((int b, _charset c)); +static void copyset P((const _charset src, _charset dst)); +static void zeroset P((_charset s)); +static void notset P((_charset s)); +static int equal P((const _charset s1, const _charset s2)); +static int charset_index P((const _charset s)); +static _token lex P((void)); +static void addtok P((_token t)); +static void atom P((void)); +static void closure P((void)); +static void branch P((void)); +static void regexp P((void)); +static void copy P((const _position_set *src, _position_set *dst)); +static void insert P((_position p, _position_set *s)); +static void merge P((_position_set *s1, _position_set *s2, _position_set *m)); +static void delete P((_position p, _position_set *s)); +static int state_index P((struct regexp *r, _position_set *s, + int newline, int letter)); +static void epsclosure P((_position_set *s, struct regexp *r)); +static void build_state P((int s, struct regexp *r)); +static void build_state_zero P((struct regexp *r)); +static char *icatalloc P((char *old, const char *new)); +static char *icpyalloc P((const char *string)); +static char *istrstr P((char *lookin, char *lookfor)); +static void ifree P((char *cp)); +static void freelist P((char **cpp)); +static char **enlist P((char **cpp, char *new, size_t len)); +static char **comsubs P((char *left, char *right)); +static char **addlists P((char **old, char **new)); +static char **inboth P((char **left, char **right)); +static void resetmust P((must *mp)); +static void regmust P((struct regexp *r)); + +#undef P + +static ptr_t +xcalloc(n, s) + int n; + size_t s; +{ + ptr_t r = calloc(n, s); + + if (NULL == r) + regerror("Memory exhausted"); /* regerror does not return */ + return r; +} + +static ptr_t +xmalloc(n) + size_t n; +{ + ptr_t r = malloc(n); + + assert(n != 0); + if (NULL == r) + regerror("Memory exhausted"); + return r; +} + +static ptr_t +xrealloc(p, n) + ptr_t p; + size_t n; +{ + ptr_t r = realloc(p, n); + + assert(n != 0); + if (NULL == r) + regerror("Memory exhausted"); + return r; +} + +#define CALLOC(p, t, n) ((p) = (t *) xcalloc((n), sizeof (t))) +#undef MALLOC +#define MALLOC(p, t, n) ((p) = (t *) xmalloc((n) * sizeof (t))) +#define REALLOC(p, t, n) ((p) = (t *) xrealloc((ptr_t) (p), (n) * sizeof (t))) + +/* Reallocate an array of type t if nalloc is too small for index. */ +#define REALLOC_IF_NECESSARY(p, t, nalloc, index) \ + if ((index) >= (nalloc)) \ + { \ + while ((index) >= (nalloc)) \ + (nalloc) *= 2; \ + REALLOC(p, t, nalloc); \ + } + +/* Stuff pertaining to charsets. */ + +static int +tstbit(b, c) + int b; + _charset c; +{ + return c[b / INTBITS] & 1 << b % INTBITS; +} + +static void +setbit(b, c) + int b; + _charset c; +{ + c[b / INTBITS] |= 1 << b % INTBITS; +} + +static void +clrbit(b, c) + int b; + _charset c; +{ + c[b / INTBITS] &= ~(1 << b % INTBITS); +} + +static void +copyset(src, dst) + const _charset src; + _charset dst; +{ + int i; + + for (i = 0; i < _CHARSET_INTS; ++i) + dst[i] = src[i]; +} + +static void +zeroset(s) + _charset s; +{ + int i; + + for (i = 0; i < _CHARSET_INTS; ++i) + s[i] = 0; +} + +static void +notset(s) + _charset s; +{ + int i; + + for (i = 0; i < _CHARSET_INTS; ++i) + s[i] = ~s[i]; +} + +static int +equal(s1, s2) + const _charset s1; + const _charset s2; +{ + int i; + + for (i = 0; i < _CHARSET_INTS; ++i) + if (s1[i] != s2[i]) + return 0; + return 1; +} + +/* A pointer to the current regexp is kept here during parsing. */ +static struct regexp *reg; + +/* Find the index of charset s in reg->charsets, or allocate a new charset. */ +static int +charset_index(s) + const _charset s; +{ + int i; + + for (i = 0; i < reg->cindex; ++i) + if (equal(s, reg->charsets[i])) + return i; + REALLOC_IF_NECESSARY(reg->charsets, _charset, reg->calloc, reg->cindex); + ++reg->cindex; + copyset(s, reg->charsets[i]); + return i; +} + +/* Syntax bits controlling the behavior of the lexical analyzer. */ +static syntax_bits, syntax_bits_set; + +/* Flag for case-folding letters into sets. */ +static case_fold; + +/* Entry point to set syntax options. */ +void +regsyntax(bits, fold) + int bits; + int fold; +{ + syntax_bits_set = 1; + syntax_bits = bits; + case_fold = fold; +} + +/* Lexical analyzer. */ +static const char *lexstart; /* Pointer to beginning of input string. */ +static const char *lexptr; /* Pointer to next input character. */ +static lexleft; /* Number of characters remaining. */ +static caret_allowed; /* True if backward context allows ^ + (meaningful only if RE_CONTEXT_INDEP_OPS + is turned off). */ +static closure_allowed; /* True if backward context allows closures + (meaningful only if RE_CONTEXT_INDEP_OPS + is turned off). */ + +/* Note that characters become unsigned here. */ +#define FETCH(c, eoferr) \ + { \ + if (! lexleft) \ + if (eoferr != NULL) \ + regerror(eoferr); \ + else \ + return _END; \ + (c) = (unsigned char) *lexptr++; \ + --lexleft; \ + } + +static _token +lex() +{ + _token c, c2; + int invert; + _charset cset; + + FETCH(c, (char *) 0); + switch (c) + { + case '^': + if (! (syntax_bits & RE_CONTEXT_INDEP_OPS) + && (!caret_allowed || + (syntax_bits & RE_TIGHT_VBAR) && lexptr - 1 != lexstart)) + goto normal_char; + caret_allowed = 0; + return syntax_bits & RE_TIGHT_VBAR ? _ALLBEGLINE : _BEGLINE; + + case '$': + if (syntax_bits & RE_CONTEXT_INDEP_OPS || !lexleft + || (! (syntax_bits & RE_TIGHT_VBAR) + && ((syntax_bits & RE_NO_BK_PARENS + ? lexleft > 0 && *lexptr == ')' + : lexleft > 1 && *lexptr == '\\' && lexptr[1] == ')') + || (syntax_bits & RE_NO_BK_VBAR + ? lexleft > 0 && *lexptr == '|' + : lexleft > 1 && *lexptr == '\\' && lexptr[1] == '|')))) + return syntax_bits & RE_TIGHT_VBAR ? _ALLENDLINE : _ENDLINE; + goto normal_char; + + case '\\': + FETCH(c, "Unfinished \\ quote"); + switch (c) + { + case '1': + case '2': + case '3': + case '4': + case '5': + case '6': + case '7': + case '8': + case '9': + caret_allowed = 0; + closure_allowed = 1; + return _BACKREF; + + case '<': + caret_allowed = 0; + return _BEGWORD; + + case '>': + caret_allowed = 0; + return _ENDWORD; + + case 'b': + caret_allowed = 0; + return _LIMWORD; + + case 'B': + caret_allowed = 0; + return _NOTLIMWORD; + + case 'w': + case 'W': + zeroset(cset); + for (c2 = 0; c2 < _NOTCHAR; ++c2) + if (ISALNUM(c2)) + setbit(c2, cset); + if (c == 'W') + notset(cset); + caret_allowed = 0; + closure_allowed = 1; + return _SET + charset_index(cset); + + case '?': + if (syntax_bits & RE_BK_PLUS_QM) + goto qmark; + goto normal_char; + + case '+': + if (syntax_bits & RE_BK_PLUS_QM) + goto plus; + goto normal_char; + + case '|': + if (! (syntax_bits & RE_NO_BK_VBAR)) + goto or; + goto normal_char; + + case '(': + if (! (syntax_bits & RE_NO_BK_PARENS)) + goto lparen; + goto normal_char; + + case ')': + if (! (syntax_bits & RE_NO_BK_PARENS)) + goto rparen; + goto normal_char; + + default: + goto normal_char; + } + + case '?': + if (syntax_bits & RE_BK_PLUS_QM) + goto normal_char; + qmark: + if (! (syntax_bits & RE_CONTEXT_INDEP_OPS) && !closure_allowed) + goto normal_char; + return _QMARK; + + case '*': + if (! (syntax_bits & RE_CONTEXT_INDEP_OPS) && !closure_allowed) + goto normal_char; + return _STAR; + + case '+': + if (syntax_bits & RE_BK_PLUS_QM) + goto normal_char; + plus: + if (! (syntax_bits & RE_CONTEXT_INDEP_OPS) && !closure_allowed) + goto normal_char; + return _PLUS; + + case '|': + if (! (syntax_bits & RE_NO_BK_VBAR)) + goto normal_char; + or: + caret_allowed = 1; + closure_allowed = 0; + return _OR; + + case '\n': + if (! (syntax_bits & RE_NEWLINE_OR)) + goto normal_char; + goto or; + + case '(': + if (! (syntax_bits & RE_NO_BK_PARENS)) + goto normal_char; + lparen: + caret_allowed = 1; + closure_allowed = 0; + return _LPAREN; + + case ')': + if (! (syntax_bits & RE_NO_BK_PARENS)) + goto normal_char; + rparen: + caret_allowed = 0; + closure_allowed = 1; + return _RPAREN; + + case '.': + zeroset(cset); + notset(cset); + clrbit('\n', cset); + caret_allowed = 0; + closure_allowed = 1; + return _SET + charset_index(cset); + + case '[': + zeroset(cset); + FETCH(c, "Unbalanced ["); + if (c == '^') + { + FETCH(c, "Unbalanced ["); + invert = 1; + } + else + invert = 0; + do + { + FETCH(c2, "Unbalanced ["); + if ((syntax_bits & RE_AWK_CLASS_HACK) && c == '\\') + { + c = c2; + FETCH(c2, "Unbalanced ["); + } + if (c2 == '-') + { + FETCH(c2, "Unbalanced ["); + if (c2 == ']' && (syntax_bits & RE_AWK_CLASS_HACK)) + { + setbit(c, cset); + setbit('-', cset); + break; + } + while (c <= c2) + setbit(c++, cset); + FETCH(c, "Unbalanced ["); + } + else + { + setbit(c, cset); + c = c2; + } + } + while (c != ']'); + if (invert) + notset(cset); + caret_allowed = 0; + closure_allowed = 1; + return _SET + charset_index(cset); + + default: + normal_char: + caret_allowed = 0; + closure_allowed = 1; + if (case_fold && ISALPHA(c)) + { + zeroset(cset); + if (isupper(c)) + c = tolower(c); + setbit(c, cset); + setbit(toupper(c), cset); + return _SET + charset_index(cset); + } + return c; + } +} + +/* Recursive descent parser for regular expressions. */ + +static _token tok; /* Lookahead token. */ +static depth; /* Current depth of a hypothetical stack + holding deferred productions. This is + used to determine the depth that will be + required of the real stack later on in + reganalyze(). */ + +/* Add the given token to the parse tree, maintaining the depth count and + updating the maximum depth if necessary. */ +static void +addtok(t) + _token t; +{ + REALLOC_IF_NECESSARY(reg->tokens, _token, reg->talloc, reg->tindex); + reg->tokens[reg->tindex++] = t; + + switch (t) + { + case _QMARK: + case _STAR: + case _PLUS: + break; + + case _CAT: + case _OR: + --depth; + break; + + default: + ++reg->nleaves; + case _EMPTY: + ++depth; + break; + } + if (depth > reg->depth) + reg->depth = depth; +} + +/* The grammar understood by the parser is as follows. + + start: + regexp + _ALLBEGLINE regexp + regexp _ALLENDLINE + _ALLBEGLINE regexp _ALLENDLINE + + regexp: + regexp _OR branch + branch + + branch: + branch closure + closure + + closure: + closure _QMARK + closure _STAR + closure _PLUS + atom + + atom: + <normal character> + _SET + _BACKREF + _BEGLINE + _ENDLINE + _BEGWORD + _ENDWORD + _LIMWORD + _NOTLIMWORD + <empty> + + The parser builds a parse tree in postfix form in an array of tokens. */ + +#ifdef __STDC__ +static void regexp(void); +#else +static void regexp(); +#endif + +static void +atom() +{ + if (tok >= 0 && tok < _NOTCHAR || tok >= _SET || tok == _BACKREF + || tok == _BEGLINE || tok == _ENDLINE || tok == _BEGWORD + || tok == _ENDWORD || tok == _LIMWORD || tok == _NOTLIMWORD) + { + addtok(tok); + tok = lex(); + } + else if (tok == _LPAREN) + { + tok = lex(); + regexp(); + if (tok != _RPAREN) + regerror("Unbalanced ("); + tok = lex(); + } + else + addtok(_EMPTY); +} + +static void +closure() +{ + atom(); + while (tok == _QMARK || tok == _STAR || tok == _PLUS) + { + addtok(tok); + tok = lex(); + } +} + +static void +branch() +{ + closure(); + while (tok != _RPAREN && tok != _OR && tok != _ALLENDLINE && tok >= 0) + { + closure(); + addtok(_CAT); + } +} + +static void +regexp() +{ + branch(); + while (tok == _OR) + { + tok = lex(); + branch(); + addtok(_OR); + } +} + +/* Main entry point for the parser. S is a string to be parsed, len is the + length of the string, so s can include NUL characters. R is a pointer to + the struct regexp to parse into. */ +void +regparse(s, len, r) + const char *s; + size_t len; + struct regexp *r; +{ + reg = r; + lexstart = lexptr = s; + lexleft = len; + caret_allowed = 1; + closure_allowed = 0; + + if (! syntax_bits_set) + regerror("No syntax specified"); + + tok = lex(); + depth = r->depth; + + if (tok == _ALLBEGLINE) + { + addtok(_BEGLINE); + tok = lex(); + regexp(); + addtok(_CAT); + } + else + regexp(); + + if (tok == _ALLENDLINE) + { + addtok(_ENDLINE); + addtok(_CAT); + tok = lex(); + } + + if (tok != _END) + regerror("Unbalanced )"); + + addtok(_END - r->nregexps); + addtok(_CAT); + + if (r->nregexps) + addtok(_OR); + + ++r->nregexps; +} + +/* Some primitives for operating on sets of positions. */ + +/* Copy one set to another; the destination must be large enough. */ +static void +copy(src, dst) + const _position_set *src; + _position_set *dst; +{ + int i; + + for (i = 0; i < src->nelem; ++i) + dst->elems[i] = src->elems[i]; + dst->nelem = src->nelem; +} + +/* Insert a position in a set. Position sets are maintained in sorted + order according to index. If position already exists in the set with + the same index then their constraints are logically or'd together. + S->elems must point to an array large enough to hold the resulting set. */ +static void +insert(p, s) + _position p; + _position_set *s; +{ + int i; + _position t1, t2; + + for (i = 0; i < s->nelem && p.index < s->elems[i].index; ++i) + ; + if (i < s->nelem && p.index == s->elems[i].index) + s->elems[i].constraint |= p.constraint; + else + { + t1 = p; + ++s->nelem; + while (i < s->nelem) + { + t2 = s->elems[i]; + s->elems[i++] = t1; + t1 = t2; + } + } +} + +/* Merge two sets of positions into a third. The result is exactly as if + the positions of both sets were inserted into an initially empty set. */ +static void +merge(s1, s2, m) + _position_set *s1; + _position_set *s2; + _position_set *m; +{ + int i = 0, j = 0; + + m->nelem = 0; + while (i < s1->nelem && j < s2->nelem) + if (s1->elems[i].index > s2->elems[j].index) + m->elems[m->nelem++] = s1->elems[i++]; + else if (s1->elems[i].index < s2->elems[j].index) + m->elems[m->nelem++] = s2->elems[j++]; + else + { + m->elems[m->nelem] = s1->elems[i++]; + m->elems[m->nelem++].constraint |= s2->elems[j++].constraint; + } + while (i < s1->nelem) + m->elems[m->nelem++] = s1->elems[i++]; + while (j < s2->nelem) + m->elems[m->nelem++] = s2->elems[j++]; +} + +/* Delete a position from a set. */ +static void +delete(p, s) + _position p; + _position_set *s; +{ + int i; + + for (i = 0; i < s->nelem; ++i) + if (p.index == s->elems[i].index) + break; + if (i < s->nelem) + for (--s->nelem; i < s->nelem; ++i) + s->elems[i] = s->elems[i + 1]; +} + +/* Find the index of the state corresponding to the given position set with + the given preceding context, or create a new state if there is no such + state. Newline and letter tell whether we got here on a newline or + letter, respectively. */ +static int +state_index(r, s, newline, letter) + struct regexp *r; + _position_set *s; + int newline; + int letter; +{ + int hash = 0; + int constraint; + int i, j; + + newline = newline ? 1 : 0; + letter = letter ? 1 : 0; + + for (i = 0; i < s->nelem; ++i) + hash ^= s->elems[i].index + s->elems[i].constraint; + + /* Try to find a state that exactly matches the proposed one. */ + for (i = 0; i < r->sindex; ++i) + { + if (hash != r->states[i].hash || s->nelem != r->states[i].elems.nelem + || newline != r->states[i].newline || letter != r->states[i].letter) + continue; + for (j = 0; j < s->nelem; ++j) + if (s->elems[j].constraint + != r->states[i].elems.elems[j].constraint + || s->elems[j].index != r->states[i].elems.elems[j].index) + break; + if (j == s->nelem) + return i; + } + + /* We'll have to create a new state. */ + REALLOC_IF_NECESSARY(r->states, _dfa_state, r->salloc, r->sindex); + r->states[i].hash = hash; + MALLOC(r->states[i].elems.elems, _position, s->nelem); + copy(s, &r->states[i].elems); + r->states[i].newline = newline; + r->states[i].letter = letter; + r->states[i].backref = 0; + r->states[i].constraint = 0; + r->states[i].first_end = 0; + for (j = 0; j < s->nelem; ++j) + if (r->tokens[s->elems[j].index] < 0) + { + constraint = s->elems[j].constraint; + if (_SUCCEEDS_IN_CONTEXT(constraint, newline, 0, letter, 0) + || _SUCCEEDS_IN_CONTEXT(constraint, newline, 0, letter, 1) + || _SUCCEEDS_IN_CONTEXT(constraint, newline, 1, letter, 0) + || _SUCCEEDS_IN_CONTEXT(constraint, newline, 1, letter, 1)) + r->states[i].constraint |= constraint; + if (! r->states[i].first_end) + r->states[i].first_end = r->tokens[s->elems[j].index]; + } + else if (r->tokens[s->elems[j].index] == _BACKREF) + { + r->states[i].constraint = _NO_CONSTRAINT; + r->states[i].backref = 1; + } + + ++r->sindex; + + return i; +} + +/* Find the epsilon closure of a set of positions. If any position of the set + contains a symbol that matches the empty string in some context, replace + that position with the elements of its follow labeled with an appropriate + constraint. Repeat exhaustively until no funny positions are left. + S->elems must be large enough to hold the result. */ +static void +epsclosure(s, r) + _position_set *s; + struct regexp *r; +{ + int i, j; + int *visited; + _position p, old; + + MALLOC(visited, int, r->tindex); + for (i = 0; i < r->tindex; ++i) + visited[i] = 0; + + for (i = 0; i < s->nelem; ++i) + if (r->tokens[s->elems[i].index] >= _NOTCHAR + && r->tokens[s->elems[i].index] != _BACKREF + && r->tokens[s->elems[i].index] < _SET) + { + old = s->elems[i]; + p.constraint = old.constraint; + delete(s->elems[i], s); + if (visited[old.index]) + { + --i; + continue; + } + visited[old.index] = 1; + switch (r->tokens[old.index]) + { + case _BEGLINE: + p.constraint &= _BEGLINE_CONSTRAINT; + break; + case _ENDLINE: + p.constraint &= _ENDLINE_CONSTRAINT; + break; + case _BEGWORD: + p.constraint &= _BEGWORD_CONSTRAINT; + break; + case _ENDWORD: + p.constraint &= _ENDWORD_CONSTRAINT; + break; + case _LIMWORD: + p.constraint &= _ENDWORD_CONSTRAINT; + break; + case _NOTLIMWORD: + p.constraint &= _NOTLIMWORD_CONSTRAINT; + break; + default: + break; + } + for (j = 0; j < r->follows[old.index].nelem; ++j) + { + p.index = r->follows[old.index].elems[j].index; + insert(p, s); + } + /* Force rescan to start at the beginning. */ + i = -1; + } + + free(visited); +} + +/* Perform bottom-up analysis on the parse tree, computing various functions. + Note that at this point, we're pretending constructs like \< are real + characters rather than constraints on what can follow them. + + Nullable: A node is nullable if it is at the root of a regexp that can + match the empty string. + * _EMPTY leaves are nullable. + * No other leaf is nullable. + * A _QMARK or _STAR node is nullable. + * A _PLUS node is nullable if its argument is nullable. + * A _CAT node is nullable if both its arguments are nullable. + * An _OR node is nullable if either argument is nullable. + + Firstpos: The firstpos of a node is the set of positions (nonempty leaves) + that could correspond to the first character of a string matching the + regexp rooted at the given node. + * _EMPTY leaves have empty firstpos. + * The firstpos of a nonempty leaf is that leaf itself. + * The firstpos of a _QMARK, _STAR, or _PLUS node is the firstpos of its + argument. + * The firstpos of a _CAT node is the firstpos of the left argument, union + the firstpos of the right if the left argument is nullable. + * The firstpos of an _OR node is the union of firstpos of each argument. + + Lastpos: The lastpos of a node is the set of positions that could + correspond to the last character of a string matching the regexp at + the given node. + * _EMPTY leaves have empty lastpos. + * The lastpos of a nonempty leaf is that leaf itself. + * The lastpos of a _QMARK, _STAR, or _PLUS node is the lastpos of its + argument. + * The lastpos of a _CAT node is the lastpos of its right argument, union + the lastpos of the left if the right argument is nullable. + * The lastpos of an _OR node is the union of the lastpos of each argument. + + Follow: The follow of a position is the set of positions that could + correspond to the character following a character matching the node in + a string matching the regexp. At this point we consider special symbols + that match the empty string in some context to be just normal characters. + Later, if we find that a special symbol is in a follow set, we will + replace it with the elements of its follow, labeled with an appropriate + constraint. + * Every node in the firstpos of the argument of a _STAR or _PLUS node is in + the follow of every node in the lastpos. + * Every node in the firstpos of the second argument of a _CAT node is in + the follow of every node in the lastpos of the first argument. + + Because of the postfix representation of the parse tree, the depth-first + analysis is conveniently done by a linear scan with the aid of a stack. + Sets are stored as arrays of the elements, obeying a stack-like allocation + scheme; the number of elements in each set deeper in the stack can be + used to determine the address of a particular set's array. */ +void +reganalyze(r, searchflag) + struct regexp *r; + int searchflag; +{ + int *nullable; /* Nullable stack. */ + int *nfirstpos; /* Element count stack for firstpos sets. */ + _position *firstpos; /* Array where firstpos elements are stored. */ + int *nlastpos; /* Element count stack for lastpos sets. */ + _position *lastpos; /* Array where lastpos elements are stored. */ + int *nalloc; /* Sizes of arrays allocated to follow sets. */ + _position_set tmp; /* Temporary set for merging sets. */ + _position_set merged; /* Result of merging sets. */ + int wants_newline; /* True if some position wants newline info. */ + int *o_nullable; + int *o_nfirst, *o_nlast; + _position *o_firstpos, *o_lastpos; + int i, j; + _position *pos; + + r->searchflag = searchflag; + + MALLOC(nullable, int, r->depth); + o_nullable = nullable; + MALLOC(nfirstpos, int, r->depth); + o_nfirst = nfirstpos; + MALLOC(firstpos, _position, r->nleaves); + o_firstpos = firstpos, firstpos += r->nleaves; + MALLOC(nlastpos, int, r->depth); + o_nlast = nlastpos; + MALLOC(lastpos, _position, r->nleaves); + o_lastpos = lastpos, lastpos += r->nleaves; + MALLOC(nalloc, int, r->tindex); + for (i = 0; i < r->tindex; ++i) + nalloc[i] = 0; + MALLOC(merged.elems, _position, r->nleaves); + + CALLOC(r->follows, _position_set, r->tindex); + + for (i = 0; i < r->tindex; ++i) + switch (r->tokens[i]) + { + case _EMPTY: + /* The empty set is nullable. */ + *nullable++ = 1; + + /* The firstpos and lastpos of the empty leaf are both empty. */ + *nfirstpos++ = *nlastpos++ = 0; + break; + + case _STAR: + case _PLUS: + /* Every element in the firstpos of the argument is in the follow + of every element in the lastpos. */ + tmp.nelem = nfirstpos[-1]; + tmp.elems = firstpos; + pos = lastpos; + for (j = 0; j < nlastpos[-1]; ++j) + { + merge(&tmp, &r->follows[pos[j].index], &merged); + REALLOC_IF_NECESSARY(r->follows[pos[j].index].elems, _position, + nalloc[pos[j].index], merged.nelem - 1); + copy(&merged, &r->follows[pos[j].index]); + } + + case _QMARK: + /* A _QMARK or _STAR node is automatically nullable. */ + if (r->tokens[i] != _PLUS) + nullable[-1] = 1; + break; + + case _CAT: + /* Every element in the firstpos of the second argument is in the + follow of every element in the lastpos of the first argument. */ + tmp.nelem = nfirstpos[-1]; + tmp.elems = firstpos; + pos = lastpos + nlastpos[-1]; + for (j = 0; j < nlastpos[-2]; ++j) + { + merge(&tmp, &r->follows[pos[j].index], &merged); + REALLOC_IF_NECESSARY(r->follows[pos[j].index].elems, _position, + nalloc[pos[j].index], merged.nelem - 1); + copy(&merged, &r->follows[pos[j].index]); + } + + /* The firstpos of a _CAT node is the firstpos of the first argument, + union that of the second argument if the first is nullable. */ + if (nullable[-2]) + nfirstpos[-2] += nfirstpos[-1]; + else + firstpos += nfirstpos[-1]; + --nfirstpos; + + /* The lastpos of a _CAT node is the lastpos of the second argument, + union that of the first argument if the second is nullable. */ + if (nullable[-1]) + nlastpos[-2] += nlastpos[-1]; + else + { + pos = lastpos + nlastpos[-2]; + for (j = nlastpos[-1] - 1; j >= 0; --j) + pos[j] = lastpos[j]; + lastpos += nlastpos[-2]; + nlastpos[-2] = nlastpos[-1]; + } + --nlastpos; + + /* A _CAT node is nullable if both arguments are nullable. */ + nullable[-2] = nullable[-1] && nullable[-2]; + --nullable; + break; + + case _OR: + /* The firstpos is the union of the firstpos of each argument. */ + nfirstpos[-2] += nfirstpos[-1]; + --nfirstpos; + + /* The lastpos is the union of the lastpos of each argument. */ + nlastpos[-2] += nlastpos[-1]; + --nlastpos; + + /* An _OR node is nullable if either argument is nullable. */ + nullable[-2] = nullable[-1] || nullable[-2]; + --nullable; + break; + + default: + /* Anything else is a nonempty position. (Note that special + constructs like \< are treated as nonempty strings here; + an "epsilon closure" effectively makes them nullable later. + Backreferences have to get a real position so we can detect + transitions on them later. But they are nullable. */ + *nullable++ = r->tokens[i] == _BACKREF; + + /* This position is in its own firstpos and lastpos. */ + *nfirstpos++ = *nlastpos++ = 1; + --firstpos, --lastpos; + firstpos->index = lastpos->index = i; + firstpos->constraint = lastpos->constraint = _NO_CONSTRAINT; + + /* Allocate the follow set for this position. */ + nalloc[i] = 1; + MALLOC(r->follows[i].elems, _position, nalloc[i]); + break; + } + + /* For each follow set that is the follow set of a real position, replace + it with its epsilon closure. */ + for (i = 0; i < r->tindex; ++i) + if (r->tokens[i] < _NOTCHAR || r->tokens[i] == _BACKREF + || r->tokens[i] >= _SET) + { + copy(&r->follows[i], &merged); + epsclosure(&merged, r); + if (r->follows[i].nelem < merged.nelem) + REALLOC(r->follows[i].elems, _position, merged.nelem); + copy(&merged, &r->follows[i]); + } + + /* Get the epsilon closure of the firstpos of the regexp. The result will + be the set of positions of state 0. */ + merged.nelem = 0; + for (i = 0; i < nfirstpos[-1]; ++i) + insert(firstpos[i], &merged); + epsclosure(&merged, r); + + /* Check if any of the positions of state 0 will want newline context. */ + wants_newline = 0; + for (i = 0; i < merged.nelem; ++i) + if (_PREV_NEWLINE_DEPENDENT(merged.elems[i].constraint)) + wants_newline = 1; + + /* Build the initial state. */ + r->salloc = 1; + r->sindex = 0; + MALLOC(r->states, _dfa_state, r->salloc); + state_index(r, &merged, wants_newline, 0); + + free(o_nullable); + free(o_nfirst); + free(o_firstpos); + free(o_nlast); + free(o_lastpos); + free(nalloc); + free(merged.elems); +} + +/* Find, for each character, the transition out of state s of r, and store + it in the appropriate slot of trans. + + We divide the positions of s into groups (positions can appear in more + than one group). Each group is labeled with a set of characters that + every position in the group matches (taking into account, if necessary, + preceding context information of s). For each group, find the union + of the its elements' follows. This set is the set of positions of the + new state. For each character in the group's label, set the transition + on this character to be to a state corresponding to the set's positions, + and its associated backward context information, if necessary. + + If we are building a searching matcher, we include the positions of state + 0 in every state. + + The collection of groups is constructed by building an equivalence-class + partition of the positions of s. + + For each position, find the set of characters C that it matches. Eliminate + any characters from C that fail on grounds of backward context. + + Search through the groups, looking for a group whose label L has nonempty + intersection with C. If L - C is nonempty, create a new group labeled + L - C and having the same positions as the current group, and set L to + the intersection of L and C. Insert the position in this group, set + C = C - L, and resume scanning. + + If after comparing with every group there are characters remaining in C, + create a new group labeled with the characters of C and insert this + position in that group. */ +void +regstate(s, r, trans) + int s; + struct regexp *r; + int trans[]; +{ + _position_set grps[_NOTCHAR]; /* As many as will ever be needed. */ + _charset labels[_NOTCHAR]; /* Labels corresponding to the groups. */ + int ngrps = 0; /* Number of groups actually used. */ + _position pos; /* Current position being considered. */ + _charset matches; /* Set of matching characters. */ + int matchesf; /* True if matches is nonempty. */ + _charset intersect; /* Intersection with some label set. */ + int intersectf; /* True if intersect is nonempty. */ + _charset leftovers; /* Stuff in the label that didn't match. */ + int leftoversf; /* True if leftovers is nonempty. */ + static _charset letters; /* Set of characters considered letters. */ + static _charset newline; /* Set of characters that aren't newline. */ + _position_set follows; /* Union of the follows of some group. */ + _position_set tmp; /* Temporary space for merging sets. */ + int state; /* New state. */ + int wants_newline; /* New state wants to know newline context. */ + int state_newline; /* New state on a newline transition. */ + int wants_letter; /* New state wants to know letter context. */ + int state_letter; /* New state on a letter transition. */ + static initialized; /* Flag for static initialization. */ + int i, j, k; + + /* Initialize the set of letters, if necessary. */ + if (! initialized) + { + initialized = 1; + for (i = 0; i < _NOTCHAR; ++i) + if (ISALNUM(i)) + setbit(i, letters); + setbit('\n', newline); + } + + zeroset(matches); + + for (i = 0; i < r->states[s].elems.nelem; ++i) + { + pos = r->states[s].elems.elems[i]; + if (r->tokens[pos.index] >= 0 && r->tokens[pos.index] < _NOTCHAR) + setbit(r->tokens[pos.index], matches); + else if (r->tokens[pos.index] >= _SET) + copyset(r->charsets[r->tokens[pos.index] - _SET], matches); + else + continue; + + /* Some characters may need to be climinated from matches because + they fail in the current context. */ + if (pos.constraint != 0xff) + { + if (! _MATCHES_NEWLINE_CONTEXT(pos.constraint, + r->states[s].newline, 1)) + clrbit('\n', matches); + if (! _MATCHES_NEWLINE_CONTEXT(pos.constraint, + r->states[s].newline, 0)) + for (j = 0; j < _CHARSET_INTS; ++j) + matches[j] &= newline[j]; + if (! _MATCHES_LETTER_CONTEXT(pos.constraint, + r->states[s].letter, 1)) + for (j = 0; j < _CHARSET_INTS; ++j) + matches[j] &= ~letters[j]; + if (! _MATCHES_LETTER_CONTEXT(pos.constraint, + r->states[s].letter, 0)) + for (j = 0; j < _CHARSET_INTS; ++j) + matches[j] &= letters[j]; + + /* If there are no characters left, there's no point in going on. */ + for (j = 0; j < _CHARSET_INTS && !matches[j]; ++j) + ; + if (j == _CHARSET_INTS) + continue; + } + + for (j = 0; j < ngrps; ++j) + { + /* If matches contains a single character only, and the current + group's label doesn't contain that character, go on to the + next group. */ + if (r->tokens[pos.index] >= 0 && r->tokens[pos.index] < _NOTCHAR + && !tstbit(r->tokens[pos.index], labels[j])) + continue; + + /* Check if this group's label has a nonempty intersection with + matches. */ + intersectf = 0; + for (k = 0; k < _CHARSET_INTS; ++k) + (intersect[k] = matches[k] & labels[j][k]) ? intersectf = 1 : 0; + if (! intersectf) + continue; + + /* It does; now find the set differences both ways. */ + leftoversf = matchesf = 0; + for (k = 0; k < _CHARSET_INTS; ++k) + { + /* Even an optimizing compiler can't know this for sure. */ + int match = matches[k], label = labels[j][k]; + + (leftovers[k] = ~match & label) ? leftoversf = 1 : 0; + (matches[k] = match & ~label) ? matchesf = 1 : 0; + } + + /* If there were leftovers, create a new group labeled with them. */ + if (leftoversf) + { + copyset(leftovers, labels[ngrps]); + copyset(intersect, labels[j]); + MALLOC(grps[ngrps].elems, _position, r->nleaves); + copy(&grps[j], &grps[ngrps]); + ++ngrps; + } + + /* Put the position in the current group. Note that there is no + reason to call insert() here. */ + grps[j].elems[grps[j].nelem++] = pos; + + /* If every character matching the current position has been + accounted for, we're done. */ + if (! matchesf) + break; + } + + /* If we've passed the last group, and there are still characters + unaccounted for, then we'll have to create a new group. */ + if (j == ngrps) + { + copyset(matches, labels[ngrps]); + zeroset(matches); + MALLOC(grps[ngrps].elems, _position, r->nleaves); + grps[ngrps].nelem = 1; + grps[ngrps].elems[0] = pos; + ++ngrps; + } + } + + MALLOC(follows.elems, _position, r->nleaves); + MALLOC(tmp.elems, _position, r->nleaves); + + /* If we are a searching matcher, the default transition is to a state + containing the positions of state 0, otherwise the default transition + is to fail miserably. */ + if (r->searchflag) + { + wants_newline = 0; + wants_letter = 0; + for (i = 0; i < r->states[0].elems.nelem; ++i) + { + if (_PREV_NEWLINE_DEPENDENT(r->states[0].elems.elems[i].constraint)) + wants_newline = 1; + if (_PREV_LETTER_DEPENDENT(r->states[0].elems.elems[i].constraint)) + wants_letter = 1; + } + copy(&r->states[0].elems, &follows); + state = state_index(r, &follows, 0, 0); + if (wants_newline) + state_newline = state_index(r, &follows, 1, 0); + else + state_newline = state; + if (wants_letter) + state_letter = state_index(r, &follows, 0, 1); + else + state_letter = state; + for (i = 0; i < _NOTCHAR; ++i) + if (i == '\n') + trans[i] = state_newline; + else if (ISALNUM(i)) + trans[i] = state_letter; + else + trans[i] = state; + } + else + for (i = 0; i < _NOTCHAR; ++i) + trans[i] = -1; + + for (i = 0; i < ngrps; ++i) + { + follows.nelem = 0; + + /* Find the union of the follows of the positions of the group. + This is a hideously inefficient loop. Fix it someday. */ + for (j = 0; j < grps[i].nelem; ++j) + for (k = 0; k < r->follows[grps[i].elems[j].index].nelem; ++k) + insert(r->follows[grps[i].elems[j].index].elems[k], &follows); + + /* If we are building a searching matcher, throw in the positions + of state 0 as well. */ + if (r->searchflag) + for (j = 0; j < r->states[0].elems.nelem; ++j) + insert(r->states[0].elems.elems[j], &follows); + + /* Find out if the new state will want any context information. */ + wants_newline = 0; + if (tstbit('\n', labels[i])) + for (j = 0; j < follows.nelem; ++j) + if (_PREV_NEWLINE_DEPENDENT(follows.elems[j].constraint)) + wants_newline = 1; + + wants_letter = 0; + for (j = 0; j < _CHARSET_INTS; ++j) + if (labels[i][j] & letters[j]) + break; + if (j < _CHARSET_INTS) + for (j = 0; j < follows.nelem; ++j) + if (_PREV_LETTER_DEPENDENT(follows.elems[j].constraint)) + wants_letter = 1; + + /* Find the state(s) corresponding to the union of the follows. */ + state = state_index(r, &follows, 0, 0); + if (wants_newline) + state_newline = state_index(r, &follows, 1, 0); + else + state_newline = state; + if (wants_letter) + state_letter = state_index(r, &follows, 0, 1); + else + state_letter = state; + + /* Set the transitions for each character in the current label. */ + for (j = 0; j < _CHARSET_INTS; ++j) + for (k = 0; k < INTBITS; ++k) + if (labels[i][j] & 1 << k) + { + int c = j * INTBITS + k; + + if (c == '\n') + trans[c] = state_newline; + else if (ISALNUM(c)) + trans[c] = state_letter; + else if (c < _NOTCHAR) + trans[c] = state; + } + } + + for (i = 0; i < ngrps; ++i) + free(grps[i].elems); + free(follows.elems); + free(tmp.elems); +} + +/* Some routines for manipulating a compiled regexp's transition tables. + Each state may or may not have a transition table; if it does, and it + is a non-accepting state, then r->trans[state] points to its table. + If it is an accepting state then r->fails[state] points to its table. + If it has no table at all, then r->trans[state] is NULL. + TODO: Improve this comment, get rid of the unnecessary redundancy. */ + +static void +build_state(s, r) + int s; + struct regexp *r; +{ + int *trans; /* The new transition table. */ + int i; + + /* Set an upper limit on the number of transition tables that will ever + exist at once. 1024 is arbitrary. The idea is that the frequently + used transition tables will be quickly rebuilt, whereas the ones that + were only needed once or twice will be cleared away. */ + if (r->trcount >= 1024) + { + for (i = 0; i < r->tralloc; ++i) + if (r->trans[i]) + { + free((ptr_t) r->trans[i]); + r->trans[i] = NULL; + } + else if (r->fails[i]) + { + free((ptr_t) r->fails[i]); + r->fails[i] = NULL; + } + r->trcount = 0; + } + + ++r->trcount; + + /* Set up the success bits for this state. */ + r->success[s] = 0; + if (ACCEPTS_IN_CONTEXT(r->states[s].newline, 1, r->states[s].letter, 0, + s, *r)) + r->success[s] |= 4; + if (ACCEPTS_IN_CONTEXT(r->states[s].newline, 0, r->states[s].letter, 1, + s, *r)) + r->success[s] |= 2; + if (ACCEPTS_IN_CONTEXT(r->states[s].newline, 0, r->states[s].letter, 0, + s, *r)) + r->success[s] |= 1; + + MALLOC(trans, int, _NOTCHAR); + regstate(s, r, trans); + + /* Now go through the new transition table, and make sure that the trans + and fail arrays are allocated large enough to hold a pointer for the + largest state mentioned in the table. */ + for (i = 0; i < _NOTCHAR; ++i) + if (trans[i] >= r->tralloc) + { + int oldalloc = r->tralloc; + + while (trans[i] >= r->tralloc) + r->tralloc *= 2; + REALLOC(r->realtrans, int *, r->tralloc + 1); + r->trans = r->realtrans + 1; + REALLOC(r->fails, int *, r->tralloc); + REALLOC(r->success, int, r->tralloc); + REALLOC(r->newlines, int, r->tralloc); + while (oldalloc < r->tralloc) + { + r->trans[oldalloc] = NULL; + r->fails[oldalloc++] = NULL; + } + } + + /* Keep the newline transition in a special place so we can use it as + a sentinel. */ + r->newlines[s] = trans['\n']; + trans['\n'] = -1; + + if (ACCEPTING(s, *r)) + r->fails[s] = trans; + else + r->trans[s] = trans; +} + +static void +build_state_zero(r) + struct regexp *r; +{ + r->tralloc = 1; + r->trcount = 0; + CALLOC(r->realtrans, int *, r->tralloc + 1); + r->trans = r->realtrans + 1; + CALLOC(r->fails, int *, r->tralloc); + MALLOC(r->success, int, r->tralloc); + MALLOC(r->newlines, int, r->tralloc); + build_state(0, r); +} + +/* Search through a buffer looking for a match to the given struct regexp. + Find the first occurrence of a string matching the regexp in the buffer, + and the shortest possible version thereof. Return a pointer to the first + character after the match, or NULL if none is found. Begin points to + the beginning of the buffer, and end points to the first character after + its end. We store a newline in *end to act as a sentinel, so end had + better point somewhere valid. Newline is a flag indicating whether to + allow newlines to be in the matching string. If count is non- + NULL it points to a place we're supposed to increment every time we + see a newline. Finally, if backref is non-NULL it points to a place + where we're supposed to store a 1 if backreferencing happened and the + match needs to be verified by a backtracking matcher. Otherwise + we store a 0 in *backref. */ +char * +regexecute(r, begin, end, newline, count, backref) + struct regexp *r; + char *begin; + char *end; + int newline; + int *count; + int *backref; +{ + register s, s1, tmp; /* Current state. */ + register unsigned char *p; /* Current input character. */ + register **trans, *t; /* Copy of r->trans so it can be optimized + into a register. */ + static sbit[_NOTCHAR]; /* Table for anding with r->success. */ + static sbit_init; + + if (! sbit_init) + { + int i; + + sbit_init = 1; + for (i = 0; i < _NOTCHAR; ++i) + if (i == '\n') + sbit[i] = 4; + else if (ISALNUM(i)) + sbit[i] = 2; + else + sbit[i] = 1; + } + + if (! r->tralloc) + build_state_zero(r); + + s = 0; + p = (unsigned char *) begin; + trans = r->trans; + *end = '\n'; + + for (;;) + { + /* The dreaded inner loop. */ + if (t = trans[s]) + do + { + s1 = t[*p++]; + if (! (t = trans[s1])) + goto last_was_s; + s = t[*p++]; + } + while (t = trans[s]); + goto last_was_s1; + last_was_s: + tmp = s, s = s1, s1 = tmp; + last_was_s1: + + if (s >= 0 && p <= (unsigned char *) end && r->fails[s]) + { + if (r->success[s] & sbit[*p]) + { + if (backref) + if (r->states[s].backref) + *backref = 1; + else + *backref = 0; + return (char *) p; + } + + s1 = s; + s = r->fails[s][*p++]; + continue; + } + + /* If the previous character was a newline, count it. */ + if (count && (char *) p <= end && p[-1] == '\n') + ++*count; + + /* Check if we've run off the end of the buffer. */ + if ((char *) p >= end) + return NULL; + + if (s >= 0) + { + build_state(s, r); + trans = r->trans; + continue; + } + + if (p[-1] == '\n' && newline) + { + s = r->newlines[s1]; + continue; + } + + s = 0; + } +} + +/* Initialize the components of a regexp that the other routines don't + initialize for themselves. */ +void +reginit(r) + struct regexp *r; +{ + r->calloc = 1; + MALLOC(r->charsets, _charset, r->calloc); + r->cindex = 0; + + r->talloc = 1; + MALLOC(r->tokens, _token, r->talloc); + r->tindex = r->depth = r->nleaves = r->nregexps = 0; + + r->searchflag = 0; + r->tralloc = 0; +} + +/* Parse and analyze a single string of the given length. */ +void +regcompile(s, len, r, searchflag) + const char *s; + size_t len; + struct regexp *r; + int searchflag; +{ + if (case_fold) /* dummy folding in service of regmust() */ + { + char *copy; + int i; + + copy = malloc(len); + if (!copy) + regerror("out of memory"); + + /* This is a complete kludge and could potentially break + \<letter> escapes . . . */ + case_fold = 0; + for (i = 0; i < len; ++i) + if (ISUPPER(s[i])) + copy[i] = tolower(s[i]); + else + copy[i] = s[i]; + + reginit(r); + r->mustn = 0; + r->must[0] = '\0'; + regparse(copy, len, r); + free(copy); + regmust(r); + reganalyze(r, searchflag); + case_fold = 1; + reginit(r); + regparse(s, len, r); + reganalyze(r, searchflag); + } + else + { + reginit(r); + regparse(s, len, r); + regmust(r); + reganalyze(r, searchflag); + } +} + +/* Free the storage held by the components of a regexp. */ +void +regfree(r) + struct regexp *r; +{ + int i; + + free((ptr_t) r->charsets); + free((ptr_t) r->tokens); + for (i = 0; i < r->sindex; ++i) + free((ptr_t) r->states[i].elems.elems); + free((ptr_t) r->states); + for (i = 0; i < r->tindex; ++i) + if (r->follows[i].elems) + free((ptr_t) r->follows[i].elems); + free((ptr_t) r->follows); + for (i = 0; i < r->tralloc; ++i) + if (r->trans[i]) + free((ptr_t) r->trans[i]); + else if (r->fails[i]) + free((ptr_t) r->fails[i]); + if (r->realtrans) + free((ptr_t) r->realtrans); + if (r->fails) + free((ptr_t) r->fails); + if (r->newlines) + free((ptr_t) r->newlines); +} + +/* +Having found the postfix representation of the regular expression, +try to find a long sequence of characters that must appear in any line +containing the r.e. +Finding a "longest" sequence is beyond the scope here; +we take an easy way out and hope for the best. +(Take "(ab|a)b"--please.) + +We do a bottom-up calculation of sequences of characters that must appear +in matches of r.e.'s represented by trees rooted at the nodes of the postfix +representation: + sequences that must appear at the left of the match ("left") + sequences that must appear at the right of the match ("right") + lists of sequences that must appear somewhere in the match ("in") + sequences that must constitute the match ("is") +When we get to the root of the tree, we use one of the longest of its +calculated "in" sequences as our answer. The sequence we find is returned in +r->must (where "r" is the single argument passed to "regmust"); +the length of the sequence is returned in r->mustn. + +The sequences calculated for the various types of node (in pseudo ANSI c) +are shown below. "p" is the operand of unary operators (and the left-hand +operand of binary operators); "q" is the right-hand operand of binary operators +. +"ZERO" means "a zero-length sequence" below. + +Type left right is in +---- ---- ----- -- -- +char c # c # c # c # c + +SET ZERO ZERO ZERO ZERO + +STAR ZERO ZERO ZERO ZERO + +QMARK ZERO ZERO ZERO ZERO + +PLUS p->left p->right ZERO p->in + +CAT (p->is==ZERO)? (q->is==ZERO)? (p->is!=ZERO && p->in plus + p->left : q->right : q->is!=ZERO) ? q->in plus + p->is##q->left p->right##q->is p->is##q->is : p->right##q->left + ZERO + +OR longest common longest common (do p->is and substrings common to + leading trailing q->is have same p->in and q->in + (sub)sequence (sub)sequence length and + of p->left of p->right content) ? + and q->left and q->right p->is : NULL + +If there's anything else we recognize in the tree, all four sequences get set +to zero-length sequences. If there's something we don't recognize in the tree, +we just return a zero-length sequence. + +Break ties in favor of infrequent letters (choosing 'zzz' in preference to +'aaa')? + +And. . .is it here or someplace that we might ponder "optimizations" such as + egrep 'psi|epsilon' -> egrep 'psi' + egrep 'pepsi|epsilon' -> egrep 'epsi' + (Yes, we now find "epsi" as a "string + that must occur", but we might also + simplify the *entire* r.e. being sought +) + grep '[c]' -> grep 'c' + grep '(ab|a)b' -> grep 'ab' + grep 'ab*' -> grep 'a' + grep 'a*b' -> grep 'b' +There are several issues: + Is optimization easy (enough)? + + Does optimization actually accomplish anything, + or is the automaton you get from "psi|epsilon" (for example) + the same as the one you get from "psi" (for example)? + + Are optimizable r.e.'s likely to be used in real-life situations + (something like 'ab*' is probably unlikely; something like is + 'psi|epsilon' is likelier)? +*/ + +static char * +icatalloc(old, new) +char * old; +const char * new; +{ + register char * result; + register int oldsize, newsize; + + newsize = (new == NULL) ? 0 : strlen(new); + if (old == NULL) + oldsize = 0; + else if (newsize == 0) + return old; + else oldsize = strlen(old); + if (old == NULL) + result = (char *) malloc(newsize + 1); + else result = (char *) realloc((void *) old, oldsize + newsize + 1); + if (result != NULL && new != NULL) + (void) strcpy(result + oldsize, new); + return result; +} + +static char * +icpyalloc(string) +const char * string; +{ + return icatalloc((char *) NULL, string); +} + +static char * +istrstr(lookin, lookfor) +char * lookin; +register char * lookfor; +{ + register char * cp; + register int len; + + len = strlen(lookfor); + for (cp = lookin; *cp != '\0'; ++cp) + if (strncmp(cp, lookfor, len) == 0) + return cp; + return NULL; +} + +static void +ifree(cp) +char * cp; +{ + if (cp != NULL) + free(cp); +} + +static void +freelist(cpp) +register char ** cpp; +{ + register int i; + + if (cpp == NULL) + return; + for (i = 0; cpp[i] != NULL; ++i) { + free(cpp[i]); + cpp[i] = NULL; + } +} + +static char ** +enlist(cpp, new, len) +register char ** cpp; +register char * new; +#ifdef __STDC__ +size_t len; +#else +int len; +#endif +{ + register int i, j; + + if (cpp == NULL) + return NULL; + if ((new = icpyalloc(new)) == NULL) { + freelist(cpp); + return NULL; + } + new[len] = '\0'; + /* + ** Is there already something in the list that's new (or longer)? + */ + for (i = 0; cpp[i] != NULL; ++i) + if (istrstr(cpp[i], new) != NULL) { + free(new); + return cpp; + } + /* + ** Eliminate any obsoleted strings. + */ + j = 0; + while (cpp[j] != NULL) + if (istrstr(new, cpp[j]) == NULL) + ++j; + else { + free(cpp[j]); + if (--i == j) + break; + cpp[j] = cpp[i]; + } + /* + ** Add the new string. + */ + cpp = (char **) realloc((char *) cpp, (i + 2) * sizeof *cpp); + if (cpp == NULL) + return NULL; + cpp[i] = new; + cpp[i + 1] = NULL; + return cpp; +} + +/* +** Given pointers to two strings, +** return a pointer to an allocated list of their distinct common substrings. +** Return NULL if something seems wild. +*/ + +static char ** +comsubs(left, right) +char * left; +char * right; +{ + register char ** cpp; + register char * lcp; + register char * rcp; + register int i, len; + + if (left == NULL || right == NULL) + return NULL; + cpp = (char **) malloc(sizeof *cpp); + if (cpp == NULL) + return NULL; + cpp[0] = NULL; + for (lcp = left; *lcp != '\0'; ++lcp) { + len = 0; + rcp = strchr(right, *lcp); + while (rcp != NULL) { + for (i = 1; lcp[i] != '\0' && lcp[i] == rcp[i]; ++i) + ; + if (i > len) + len = i; + rcp = strchr(rcp + 1, *lcp); + } + if (len == 0) + continue; +#ifdef __STDC__ + if ((cpp = enlist(cpp, lcp, (size_t)len)) == NULL) +#else + if ((cpp = enlist(cpp, lcp, len)) == NULL) +#endif + break; + } + return cpp; +} + +static char ** +addlists(old, new) +char ** old; +char ** new; +{ + register int i; + + if (old == NULL || new == NULL) + return NULL; + for (i = 0; new[i] != NULL; ++i) { + old = enlist(old, new[i], strlen(new[i])); + if (old == NULL) + break; + } + return old; +} + +/* +** Given two lists of substrings, +** return a new list giving substrings common to both. +*/ + +static char ** +inboth(left, right) +char ** left; +char ** right; +{ + register char ** both; + register char ** temp; + register int lnum, rnum; + + if (left == NULL || right == NULL) + return NULL; + both = (char **) malloc(sizeof *both); + if (both == NULL) + return NULL; + both[0] = NULL; + for (lnum = 0; left[lnum] != NULL; ++lnum) { + for (rnum = 0; right[rnum] != NULL; ++rnum) { + temp = comsubs(left[lnum], right[rnum]); + if (temp == NULL) { + freelist(both); + return NULL; + } + both = addlists(both, temp); + freelist(temp); + if (both == NULL) + return NULL; + } + } + return both; +} + +/* +typedef struct { + char ** in; + char * left; + char * right; + char * is; +} must; + */ +static void +resetmust(mp) +register must * mp; +{ + mp->left[0] = mp->right[0] = mp->is[0] = '\0'; + freelist(mp->in); +} + +static void +regmust(r) +register struct regexp * r; +{ + register must * musts; + register must * mp; + register char * result; + register int ri; + register int i; + register _token t; + static must must0; + + reg->mustn = 0; + reg->must[0] = '\0'; + musts = (must *) malloc((reg->tindex + 1) * sizeof *musts); + if (musts == NULL) + return; + mp = musts; + for (i = 0; i <= reg->tindex; ++i) + mp[i] = must0; + for (i = 0; i <= reg->tindex; ++i) { + mp[i].in = (char **) malloc(sizeof *mp[i].in); + mp[i].left = malloc(2); + mp[i].right = malloc(2); + mp[i].is = malloc(2); + if (mp[i].in == NULL || mp[i].left == NULL || + mp[i].right == NULL || mp[i].is == NULL) + goto done; + mp[i].left[0] = mp[i].right[0] = mp[i].is[0] = '\0'; + mp[i].in[0] = NULL; + } + result = ""; + for (ri = 0; ri < reg->tindex; ++ri) { + switch (t = reg->tokens[ri]) { + case _ALLBEGLINE: + case _ALLENDLINE: + case _LPAREN: + case _RPAREN: + goto done; /* "cannot happen" */ + case _EMPTY: + case _BEGLINE: + case _ENDLINE: + case _BEGWORD: + case _ENDWORD: + case _LIMWORD: + case _NOTLIMWORD: + case _BACKREF: + resetmust(mp); + break; + case _STAR: + case _QMARK: + if (mp <= musts) + goto done; /* "cannot happen" */ + --mp; + resetmust(mp); + break; + case _OR: + if (mp < &musts[2]) + goto done; /* "cannot happen" */ + { + register char ** new; + register must * lmp; + register must * rmp; + register int j, ln, rn, n; + + rmp = --mp; + lmp = --mp; + /* Guaranteed to be. Unlikely, but. . . */ + if (strcmp(lmp->is, rmp->is) != 0) + lmp->is[0] = '\0'; + /* Left side--easy */ + i = 0; + while (lmp->left[i] != '\0' && + lmp->left[i] == rmp->left[i]) + ++i; + lmp->left[i] = '\0'; + /* Right side */ + ln = strlen(lmp->right); + rn = strlen(rmp->right); + n = ln; + if (n > rn) + n = rn; + for (i = 0; i < n; ++i) + if (lmp->right[ln - i - 1] != + rmp->right[rn - i - 1]) + break; + for (j = 0; j < i; ++j) + lmp->right[j] = + lmp->right[(ln - i) + j]; + lmp->right[j] = '\0'; + new = inboth(lmp->in, rmp->in); + if (new == NULL) + goto done; + freelist(lmp->in); + free((char *) lmp->in); + lmp->in = new; + } + break; + case _PLUS: + if (mp <= musts) + goto done; /* "cannot happen" */ + --mp; + mp->is[0] = '\0'; + break; + case _END: + if (mp != &musts[1]) + goto done; /* "cannot happen" */ + for (i = 0; musts[0].in[i] != NULL; ++i) + if (strlen(musts[0].in[i]) > strlen(result)) + result = musts[0].in[i]; + goto done; + case _CAT: + if (mp < &musts[2]) + goto done; /* "cannot happen" */ + { + register must * lmp; + register must * rmp; + + rmp = --mp; + lmp = --mp; + /* + ** In. Everything in left, plus everything in + ** right, plus catenation of + ** left's right and right's left. + */ + lmp->in = addlists(lmp->in, rmp->in); + if (lmp->in == NULL) + goto done; + if (lmp->right[0] != '\0' && + rmp->left[0] != '\0') { + register char * tp; + + tp = icpyalloc(lmp->right); + if (tp == NULL) + goto done; + tp = icatalloc(tp, rmp->left); + if (tp == NULL) + goto done; + lmp->in = enlist(lmp->in, tp, + strlen(tp)); + free(tp); + if (lmp->in == NULL) + goto done; + } + /* Left-hand */ + if (lmp->is[0] != '\0') { + lmp->left = icatalloc(lmp->left, + rmp->left); + if (lmp->left == NULL) + goto done; + } + /* Right-hand */ + if (rmp->is[0] == '\0') + lmp->right[0] = '\0'; + lmp->right = icatalloc(lmp->right, rmp->right); + if (lmp->right == NULL) + goto done; + /* Guaranteed to be */ + if (lmp->is[0] != '\0' && rmp->is[0] != '\0') { + lmp->is = icatalloc(lmp->is, rmp->is); + if (lmp->is == NULL) + goto done; + } + } + break; + default: + if (t < _END) { + /* "cannot happen" */ + goto done; + } else if (t == '\0') { + /* not on *my* shift */ + goto done; + } else if (t >= _SET) { + /* easy enough */ + resetmust(mp); + } else { + /* plain character */ + resetmust(mp); + mp->is[0] = mp->left[0] = mp->right[0] = t; + mp->is[1] = mp->left[1] = mp->right[1] = '\0'; + mp->in = enlist(mp->in, mp->is, 1); + if (mp->in == NULL) + goto done; + } + break; + } + ++mp; + } +done: + (void) strncpy(reg->must, result, MUST_MAX - 1); + reg->must[MUST_MAX - 1] = '\0'; + reg->mustn = strlen(reg->must); + mp = musts; + for (i = 0; i <= reg->tindex; ++i) { + freelist(mp[i].in); + ifree((char *) mp[i].in); + ifree(mp[i].left); + ifree(mp[i].right); + ifree(mp[i].is); + } + free((char *) mp); +} |