Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * trgm_regexp.c
4 : * Regular expression matching using trigrams.
5 : *
6 : * The general idea of trigram index support for a regular expression (regex)
7 : * search is to transform the regex into a logical expression on trigrams.
8 : * For example:
9 : *
10 : * (ab|cd)efg => ((abe & bef) | (cde & def)) & efg
11 : *
12 : * If a string matches the regex, then it must match the logical expression on
13 : * trigrams. The opposite is not necessarily true, however: a string that
14 : * matches the logical expression might not match the original regex. Such
15 : * false positives are removed via recheck, by running the regular regex match
16 : * operator on the retrieved heap tuple.
17 : *
18 : * Since the trigram expression involves both AND and OR operators, we can't
19 : * expect the core index machinery to evaluate it completely. Instead, the
20 : * result of regex analysis is a list of trigrams to be sought in the index,
21 : * plus a simplified graph that is used by trigramsMatchGraph() to determine
22 : * whether a particular indexed value matches the expression.
23 : *
24 : * Converting a regex to a trigram expression is based on analysis of an
25 : * automaton corresponding to the regex. The algorithm consists of four
26 : * stages:
27 : *
28 : * 1) Compile the regexp to NFA form. This is handled by the PostgreSQL
29 : * regexp library, which provides accessors for its opaque regex_t struct
30 : * to expose the NFA state graph and the "colors" (sets of equivalent
31 : * characters) used as state transition labels.
32 : *
33 : * 2) Transform the original NFA into an expanded graph, where arcs
34 : * are labeled with trigrams that must be present in order to move from
35 : * one state to another via the arcs. The trigrams used in this stage
36 : * consist of colors, not characters, as in the original NFA.
37 : *
38 : * 3) Expand the color trigrams into regular trigrams consisting of
39 : * characters. If too many distinct trigrams are produced, trigrams are
40 : * eliminated and the graph is simplified until it's simple enough.
41 : *
42 : * 4) Finally, the resulting graph is packed into a TrgmPackedGraph struct,
43 : * and returned to the caller.
44 : *
45 : * 1) Compile the regexp to NFA form
46 : * ---------------------------------
47 : * The automaton returned by the regexp compiler is a graph where vertices
48 : * are "states" and arcs are labeled with colors. Each color represents
49 : * a set of characters, so that all characters assigned to the same color
50 : * are interchangeable, so far as matching the regexp is concerned. There
51 : * are two special states: "initial" and "final". A state can have multiple
52 : * outgoing arcs labeled with the same color, which makes the automaton
53 : * non-deterministic, because it can be in many states simultaneously.
54 : *
55 : * Note that this NFA is already lossy compared to the original regexp,
56 : * since it ignores some regex features such as lookahead constraints and
57 : * backref matching. This is OK for our purposes since it's still the case
58 : * that only strings matching the NFA can possibly satisfy the regexp.
59 : *
60 : * 2) Transform the original NFA into an expanded graph
61 : * ----------------------------------------------------
62 : * In the 2nd stage, the automaton is transformed into a graph based on the
63 : * original NFA. Each state in the expanded graph represents a state from
64 : * the original NFA, plus a prefix identifying the last two characters
65 : * (colors, to be precise) seen before entering the state. There can be
66 : * multiple states in the expanded graph for each state in the original NFA,
67 : * depending on what characters can precede it. A prefix position can be
68 : * "unknown" if it's uncertain what the preceding character was, or "blank"
69 : * if the character was a non-word character (we don't need to distinguish
70 : * which non-word character it was, so just think of all of them as blanks).
71 : *
72 : * For convenience in description, call an expanded-state identifier
73 : * (two prefix colors plus a state number from the original NFA) an
74 : * "enter key".
75 : *
76 : * Each arc of the expanded graph is labeled with a trigram that must be
77 : * present in the string to match. We can construct this from an out-arc of
78 : * the underlying NFA state by combining the expanded state's prefix with the
79 : * color label of the underlying out-arc, if neither prefix position is
80 : * "unknown". But note that some of the colors in the trigram might be
81 : * "blank". This is OK since we want to generate word-boundary trigrams as
82 : * the regular trigram machinery would, if we know that some word characters
83 : * must be adjacent to a word boundary in all strings matching the NFA.
84 : *
85 : * The expanded graph can also have fewer states than the original NFA,
86 : * because we don't bother to make a separate state entry unless the state
87 : * is reachable by a valid arc. When an enter key is reachable from a state
88 : * of the expanded graph, but we do not know a complete trigram associated
89 : * with that transition, we cannot make a valid arc; instead we insert the
90 : * enter key into the enterKeys list of the source state. This effectively
91 : * means that the two expanded states are not reliably distinguishable based
92 : * on examining trigrams.
93 : *
94 : * So the expanded graph resembles the original NFA, but the arcs are
95 : * labeled with trigrams instead of individual characters, and there may be
96 : * more or fewer states. It is a lossy representation of the original NFA:
97 : * any string that matches the original regexp must match the expanded graph,
98 : * but the reverse is not true.
99 : *
100 : * We build the expanded graph through a breadth-first traversal of states
101 : * reachable from the initial state. At each reachable state, we identify the
102 : * states reachable from it without traversing a predictable trigram, and add
103 : * those states' enter keys to the current state. Then we generate all
104 : * out-arcs leading out of this collection of states that have predictable
105 : * trigrams, adding their target states to the queue of states to examine.
106 : *
107 : * When building the graph, if the number of states or arcs exceed pre-defined
108 : * limits, we give up and simply mark any states not yet processed as final
109 : * states. Roughly speaking, that means that we make use of some portion from
110 : * the beginning of the regexp. Also, any colors that have too many member
111 : * characters are treated as "unknown", so that we can't derive trigrams
112 : * from them.
113 : *
114 : * 3) Expand the color trigrams into regular trigrams
115 : * --------------------------------------------------
116 : * The trigrams in the expanded graph are "color trigrams", consisting
117 : * of three consecutive colors that must be present in the string. But for
118 : * search, we need regular trigrams consisting of characters. In the 3rd
119 : * stage, the color trigrams are expanded into regular trigrams. Since each
120 : * color can represent many characters, the total number of regular trigrams
121 : * after expansion could be very large. Because searching the index for
122 : * thousands of trigrams would be slow, and would likely produce so many
123 : * false positives that we would have to traverse a large fraction of the
124 : * index, the graph is simplified further in a lossy fashion by removing
125 : * color trigrams. When a color trigram is removed, the states connected by
126 : * any arcs labeled with that trigram are merged.
127 : *
128 : * Trigrams do not all have equivalent value for searching: some of them are
129 : * more frequent and some of them are less frequent. Ideally, we would like
130 : * to know the distribution of trigrams, but we don't. But because of padding
131 : * we know for sure that the empty character is more frequent than others,
132 : * so we can penalize trigrams according to presence of whitespace. The
133 : * penalty assigned to each color trigram is the number of simple trigrams
134 : * it would produce, times the penalties[] multiplier associated with its
135 : * whitespace content. (The penalties[] constants were calculated by analysis
136 : * of some real-life text.) We eliminate color trigrams starting with the
137 : * highest-penalty one, until we get to a total penalty of no more than
138 : * WISH_TRGM_PENALTY. However, we cannot remove a color trigram if that would
139 : * lead to merging the initial and final states, so we may not be able to
140 : * reach WISH_TRGM_PENALTY. It's still okay so long as we have no more than
141 : * MAX_TRGM_COUNT simple trigrams in total, otherwise we fail.
142 : *
143 : * 4) Pack the graph into a compact representation
144 : * -----------------------------------------------
145 : * The 2nd and 3rd stages might have eliminated or merged many of the states
146 : * and trigrams created earlier, so in this final stage, the graph is
147 : * compacted and packed into a simpler struct that contains only the
148 : * information needed to evaluate it.
149 : *
150 : * ALGORITHM EXAMPLE:
151 : *
152 : * Consider the example regex "ab[cd]". This regex is transformed into the
153 : * following NFA (for simplicity we show colors as their single members):
154 : *
155 : * 4#
156 : * c/
157 : * a b /
158 : * 1* --- 2 ---- 3
159 : * \
160 : * d\
161 : * 5#
162 : *
163 : * We use * to mark initial state and # to mark final state. It's not depicted,
164 : * but states 1, 4, 5 have self-referencing arcs for all possible characters,
165 : * because this pattern can match to any part of a string.
166 : *
167 : * As the result of stage 2 we will have the following graph:
168 : *
169 : * abc abd
170 : * 2# <---- 1* ----> 3#
171 : *
172 : * The process for generating this graph is:
173 : * 1) Create state 1 with enter key (UNKNOWN, UNKNOWN, 1).
174 : * 2) Add key (UNKNOWN, "a", 2) to state 1.
175 : * 3) Add key ("a", "b", 3) to state 1.
176 : * 4) Create new state 2 with enter key ("b", "c", 4). Add an arc
177 : * from state 1 to state 2 with label trigram "abc".
178 : * 5) Mark state 2 final because state 4 of source NFA is marked as final.
179 : * 6) Create new state 3 with enter key ("b", "d", 5). Add an arc
180 : * from state 1 to state 3 with label trigram "abd".
181 : * 7) Mark state 3 final because state 5 of source NFA is marked as final.
182 : *
183 : *
184 : * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
185 : * Portions Copyright (c) 1994, Regents of the University of California
186 : *
187 : * IDENTIFICATION
188 : * contrib/pg_trgm/trgm_regexp.c
189 : *
190 : *-------------------------------------------------------------------------
191 : */
192 : #include "postgres.h"
193 :
194 : #include "catalog/pg_collation_d.h"
195 : #include "regex/regexport.h"
196 : #include "trgm.h"
197 : #include "tsearch/ts_locale.h"
198 : #include "utils/formatting.h"
199 : #include "utils/hsearch.h"
200 : #include "utils/memutils.h"
201 : #include "varatt.h"
202 :
203 : /*
204 : * Uncomment (or use -DTRGM_REGEXP_DEBUG) to print debug info,
205 : * for exploring and debugging the algorithm implementation.
206 : * This produces three graph files in /tmp, in Graphviz .gv format.
207 : * Some progress information is also printed to postmaster stderr.
208 : */
209 : /* #define TRGM_REGEXP_DEBUG */
210 :
211 : /*
212 : * These parameters are used to limit the amount of work done.
213 : * Otherwise regex processing could be too slow and memory-consuming.
214 : *
215 : * MAX_EXPANDED_STATES - How many states we allow in expanded graph
216 : * MAX_EXPANDED_ARCS - How many arcs we allow in expanded graph
217 : * MAX_TRGM_COUNT - How many simple trigrams we allow to be extracted
218 : * WISH_TRGM_PENALTY - Maximum desired sum of color trigram penalties
219 : * COLOR_COUNT_LIMIT - Maximum number of characters per color
220 : */
221 : #define MAX_EXPANDED_STATES 128
222 : #define MAX_EXPANDED_ARCS 1024
223 : #define MAX_TRGM_COUNT 256
224 : #define WISH_TRGM_PENALTY 16
225 : #define COLOR_COUNT_LIMIT 256
226 :
227 : /*
228 : * Penalty multipliers for trigram counts depending on whitespace contents.
229 : * Numbers based on analysis of real-life texts.
230 : */
231 : static const float4 penalties[8] = {
232 : 1.0f, /* "aaa" */
233 : 3.5f, /* "aa " */
234 : 0.0f, /* "a a" (impossible) */
235 : 0.0f, /* "a " (impossible) */
236 : 4.2f, /* " aa" */
237 : 2.1f, /* " a " */
238 : 25.0f, /* " a" */
239 : 0.0f /* " " (impossible) */
240 : };
241 :
242 : /* Struct representing a single pg_wchar, converted back to multibyte form */
243 : typedef struct
244 : {
245 : char bytes[MAX_MULTIBYTE_CHAR_LEN];
246 : } trgm_mb_char;
247 :
248 : /*
249 : * Attributes of NFA colors:
250 : *
251 : * expandable - we know the character expansion of this color
252 : * containsNonWord - color contains non-word characters
253 : * (which will not be extracted into trigrams)
254 : * wordCharsCount - count of word characters in color
255 : * wordChars - array of this color's word characters
256 : * (which can be extracted into trigrams)
257 : *
258 : * When expandable is false, the other attributes don't matter; we just
259 : * assume this color represents unknown character(s).
260 : */
261 : typedef struct
262 : {
263 : bool expandable;
264 : bool containsNonWord;
265 : int wordCharsCount;
266 : trgm_mb_char *wordChars;
267 : } TrgmColorInfo;
268 :
269 : /*
270 : * A "prefix" is information about the colors of the last two characters read
271 : * before reaching a specific NFA state. These colors can have special values
272 : * COLOR_UNKNOWN and COLOR_BLANK. COLOR_UNKNOWN means that we have no
273 : * information, for example because we read some character of an unexpandable
274 : * color. COLOR_BLANK means that we read a non-word character.
275 : *
276 : * We call a prefix ambiguous if at least one of its colors is unknown. It's
277 : * fully ambiguous if both are unknown, partially ambiguous if only the first
278 : * is unknown. (The case of first color known, second unknown is not valid.)
279 : *
280 : * Wholly- or partly-blank prefixes are mostly handled the same as regular
281 : * color prefixes. This allows us to generate appropriate partly-blank
282 : * trigrams when the NFA requires word character(s) to appear adjacent to
283 : * non-word character(s).
284 : */
285 : typedef int TrgmColor;
286 :
287 : /* We assume that colors returned by the regexp engine cannot be these: */
288 : #define COLOR_UNKNOWN (-3)
289 : #define COLOR_BLANK (-4)
290 :
291 : typedef struct
292 : {
293 : TrgmColor colors[2];
294 : } TrgmPrefix;
295 :
296 : /*
297 : * Color-trigram data type. Note that some elements of the trigram can be
298 : * COLOR_BLANK, but we don't allow COLOR_UNKNOWN.
299 : */
300 : typedef struct
301 : {
302 : TrgmColor colors[3];
303 : } ColorTrgm;
304 :
305 : /*
306 : * Key identifying a state of our expanded graph: color prefix, and number
307 : * of the corresponding state in the underlying regex NFA. The color prefix
308 : * shows how we reached the regex state (to the extent that we know it).
309 : */
310 : typedef struct
311 : {
312 : TrgmPrefix prefix;
313 : int nstate;
314 : } TrgmStateKey;
315 :
316 : /*
317 : * One state of the expanded graph.
318 : *
319 : * stateKey - ID of this state
320 : * arcs - outgoing arcs of this state (List of TrgmArc)
321 : * enterKeys - enter keys reachable from this state without reading any
322 : * predictable trigram (List of TrgmStateKey)
323 : * flags - flag bits
324 : * snumber - number of this state (initially assigned as -1, -2, etc,
325 : * for debugging purposes only; then at the packaging stage,
326 : * surviving states are renumbered with positive numbers)
327 : * parent - parent state, if this state has been merged into another
328 : * tentFlags - flags this state would acquire via planned merges
329 : * tentParent - planned parent state, if considering a merge
330 : */
331 : #define TSTATE_INIT 0x01 /* flag indicating this state is initial */
332 : #define TSTATE_FIN 0x02 /* flag indicating this state is final */
333 :
334 : typedef struct TrgmState
335 : {
336 : TrgmStateKey stateKey; /* hashtable key: must be first field */
337 : List *arcs;
338 : List *enterKeys;
339 : int flags;
340 : int snumber;
341 : struct TrgmState *parent;
342 : int tentFlags;
343 : struct TrgmState *tentParent;
344 : } TrgmState;
345 :
346 : /*
347 : * One arc in the expanded graph.
348 : */
349 : typedef struct
350 : {
351 : ColorTrgm ctrgm; /* trigram needed to traverse arc */
352 : TrgmState *target; /* next state */
353 : } TrgmArc;
354 :
355 : /*
356 : * Information about arc of specific color trigram (used in stage 3)
357 : *
358 : * Contains pointers to the source and target states.
359 : */
360 : typedef struct
361 : {
362 : TrgmState *source;
363 : TrgmState *target;
364 : } TrgmArcInfo;
365 :
366 : /*
367 : * Information about color trigram (used in stage 3)
368 : *
369 : * ctrgm - trigram itself
370 : * cnumber - number of this trigram (used in the packaging stage)
371 : * count - number of simple trigrams created from this color trigram
372 : * expanded - indicates this color trigram is expanded into simple trigrams
373 : * arcs - list of all arcs labeled with this color trigram.
374 : */
375 : typedef struct
376 : {
377 : ColorTrgm ctrgm;
378 : int cnumber;
379 : int count;
380 : float4 penalty;
381 : bool expanded;
382 : List *arcs;
383 : } ColorTrgmInfo;
384 :
385 : /*
386 : * Data structure representing all the data we need during regex processing.
387 : *
388 : * regex - compiled regex
389 : * colorInfo - extracted information about regex's colors
390 : * ncolors - number of colors in colorInfo[]
391 : * states - hashtable of TrgmStates (states of expanded graph)
392 : * initState - pointer to initial state of expanded graph
393 : * queue - queue of to-be-processed TrgmStates
394 : * keysQueue - queue of to-be-processed TrgmStateKeys
395 : * arcsCount - total number of arcs of expanded graph (for resource
396 : * limiting)
397 : * overflowed - we have exceeded resource limit for transformation
398 : * colorTrgms - array of all color trigrams present in graph
399 : * colorTrgmsCount - count of those color trigrams
400 : * totalTrgmCount - total count of extracted simple trigrams
401 : */
402 : typedef struct
403 : {
404 : /* Source regexp, and color information extracted from it (stage 1) */
405 : regex_t *regex;
406 : TrgmColorInfo *colorInfo;
407 : int ncolors;
408 :
409 : /* Expanded graph (stage 2) */
410 : HTAB *states;
411 : TrgmState *initState;
412 : int nstates;
413 :
414 : /* Workspace for stage 2 */
415 : List *queue;
416 : List *keysQueue;
417 : int arcsCount;
418 : bool overflowed;
419 :
420 : /* Information about distinct color trigrams in the graph (stage 3) */
421 : ColorTrgmInfo *colorTrgms;
422 : int colorTrgmsCount;
423 : int totalTrgmCount;
424 : } TrgmNFA;
425 :
426 : /*
427 : * Final, compact representation of expanded graph.
428 : */
429 : typedef struct
430 : {
431 : int targetState; /* index of target state (zero-based) */
432 : int colorTrgm; /* index of color trigram for transition */
433 : } TrgmPackedArc;
434 :
435 : typedef struct
436 : {
437 : int arcsCount; /* number of out-arcs for this state */
438 : TrgmPackedArc *arcs; /* array of arcsCount packed arcs */
439 : } TrgmPackedState;
440 :
441 : /* "typedef struct TrgmPackedGraph TrgmPackedGraph" appears in trgm.h */
442 : struct TrgmPackedGraph
443 : {
444 : /*
445 : * colorTrigramsCount and colorTrigramGroups contain information about how
446 : * trigrams are grouped into color trigrams. "colorTrigramsCount" is the
447 : * count of color trigrams and "colorTrigramGroups" contains number of
448 : * simple trigrams for each color trigram. The array of simple trigrams
449 : * (stored separately from this struct) is ordered so that the simple
450 : * trigrams for each color trigram are consecutive, and they're in order
451 : * by color trigram number.
452 : */
453 : int colorTrigramsCount;
454 : int *colorTrigramGroups; /* array of size colorTrigramsCount */
455 :
456 : /*
457 : * The states of the simplified NFA. State number 0 is always initial
458 : * state and state number 1 is always final state.
459 : */
460 : int statesCount;
461 : TrgmPackedState *states; /* array of size statesCount */
462 :
463 : /* Temporary work space for trigramsMatchGraph() */
464 : bool *colorTrigramsActive; /* array of size colorTrigramsCount */
465 : bool *statesActive; /* array of size statesCount */
466 : int *statesQueue; /* array of size statesCount */
467 : };
468 :
469 : /*
470 : * Temporary structure for representing an arc during packaging.
471 : */
472 : typedef struct
473 : {
474 : int sourceState;
475 : int targetState;
476 : int colorTrgm;
477 : } TrgmPackArcInfo;
478 :
479 :
480 : /* prototypes for private functions */
481 : static TRGM *createTrgmNFAInternal(regex_t *regex, TrgmPackedGraph **graph,
482 : MemoryContext rcontext);
483 : static void RE_compile(regex_t *regex, text *text_re,
484 : int cflags, Oid collation);
485 : static void getColorInfo(regex_t *regex, TrgmNFA *trgmNFA);
486 : static int convertPgWchar(pg_wchar c, trgm_mb_char *result);
487 : static void transformGraph(TrgmNFA *trgmNFA);
488 : static void processState(TrgmNFA *trgmNFA, TrgmState *state);
489 : static void addKey(TrgmNFA *trgmNFA, TrgmState *state, TrgmStateKey *key);
490 : static void addKeyToQueue(TrgmNFA *trgmNFA, TrgmStateKey *key);
491 : static void addArcs(TrgmNFA *trgmNFA, TrgmState *state);
492 : static void addArc(TrgmNFA *trgmNFA, TrgmState *state, TrgmStateKey *key,
493 : TrgmColor co, TrgmStateKey *destKey);
494 : static bool validArcLabel(TrgmStateKey *key, TrgmColor co);
495 : static TrgmState *getState(TrgmNFA *trgmNFA, TrgmStateKey *key);
496 : static bool prefixContains(TrgmPrefix *prefix1, TrgmPrefix *prefix2);
497 : static bool selectColorTrigrams(TrgmNFA *trgmNFA);
498 : static TRGM *expandColorTrigrams(TrgmNFA *trgmNFA, MemoryContext rcontext);
499 : static void fillTrgm(trgm *ptrgm, trgm_mb_char s[3]);
500 : static void mergeStates(TrgmState *state1, TrgmState *state2);
501 : static int colorTrgmInfoCmp(const void *p1, const void *p2);
502 : static int colorTrgmInfoPenaltyCmp(const void *p1, const void *p2);
503 : static TrgmPackedGraph *packGraph(TrgmNFA *trgmNFA, MemoryContext rcontext);
504 : static int packArcInfoCmp(const void *a1, const void *a2);
505 :
506 : #ifdef TRGM_REGEXP_DEBUG
507 : static void printSourceNFA(regex_t *regex, TrgmColorInfo *colors, int ncolors);
508 : static void printTrgmNFA(TrgmNFA *trgmNFA);
509 : static void printTrgmColor(StringInfo buf, TrgmColor co);
510 : static void printTrgmPackedGraph(TrgmPackedGraph *packedGraph, TRGM *trigrams);
511 : #endif
512 :
513 :
514 : /*
515 : * Main entry point to process a regular expression.
516 : *
517 : * Returns an array of trigrams required by the regular expression, or NULL if
518 : * the regular expression was too complex to analyze. In addition, a packed
519 : * graph representation of the regex is returned into *graph. The results
520 : * must be allocated in rcontext (which might or might not be the current
521 : * context).
522 : */
523 : TRGM *
524 65 : createTrgmNFA(text *text_re, Oid collation,
525 : TrgmPackedGraph **graph, MemoryContext rcontext)
526 : {
527 : TRGM *trg;
528 : regex_t regex;
529 : MemoryContext tmpcontext;
530 : MemoryContext oldcontext;
531 :
532 : /*
533 : * This processing generates a great deal of cruft, which we'd like to
534 : * clean up before returning (since this function may be called in a
535 : * query-lifespan memory context). Make a temp context we can work in so
536 : * that cleanup is easy.
537 : */
538 65 : tmpcontext = AllocSetContextCreate(CurrentMemoryContext,
539 : "createTrgmNFA temporary context",
540 : ALLOCSET_DEFAULT_SIZES);
541 65 : oldcontext = MemoryContextSwitchTo(tmpcontext);
542 :
543 : /*
544 : * Stage 1: Compile the regexp into a NFA, using the regexp library.
545 : */
546 : #ifdef IGNORECASE
547 65 : RE_compile(®ex, text_re,
548 : REG_ADVANCED | REG_NOSUB | REG_ICASE, collation);
549 : #else
550 : RE_compile(®ex, text_re,
551 : REG_ADVANCED | REG_NOSUB, collation);
552 : #endif
553 :
554 65 : trg = createTrgmNFAInternal(®ex, graph, rcontext);
555 :
556 : /* Clean up all the cruft we created (including regex) */
557 65 : MemoryContextSwitchTo(oldcontext);
558 65 : MemoryContextDelete(tmpcontext);
559 :
560 65 : return trg;
561 : }
562 :
563 : /*
564 : * Body of createTrgmNFA, exclusive of regex compilation/freeing.
565 : */
566 : static TRGM *
567 65 : createTrgmNFAInternal(regex_t *regex, TrgmPackedGraph **graph,
568 : MemoryContext rcontext)
569 : {
570 : TRGM *trg;
571 : TrgmNFA trgmNFA;
572 :
573 65 : trgmNFA.regex = regex;
574 :
575 : /* Collect color information from the regex */
576 65 : getColorInfo(regex, &trgmNFA);
577 :
578 : #ifdef TRGM_REGEXP_DEBUG
579 : printSourceNFA(regex, trgmNFA.colorInfo, trgmNFA.ncolors);
580 : #endif
581 :
582 : /*
583 : * Stage 2: Create an expanded graph from the source NFA.
584 : */
585 65 : transformGraph(&trgmNFA);
586 :
587 : #ifdef TRGM_REGEXP_DEBUG
588 : printTrgmNFA(&trgmNFA);
589 : #endif
590 :
591 : /*
592 : * Fail if we were unable to make a nontrivial graph, ie it is possible to
593 : * get from the initial state to the final state without reading any
594 : * predictable trigram.
595 : */
596 65 : if (trgmNFA.initState->flags & TSTATE_FIN)
597 9 : return NULL;
598 :
599 : /*
600 : * Stage 3: Select color trigrams to expand. Fail if too many trigrams.
601 : */
602 56 : if (!selectColorTrigrams(&trgmNFA))
603 3 : return NULL;
604 :
605 : /*
606 : * Stage 4: Expand color trigrams and pack graph into final
607 : * representation.
608 : */
609 53 : trg = expandColorTrigrams(&trgmNFA, rcontext);
610 :
611 53 : *graph = packGraph(&trgmNFA, rcontext);
612 :
613 : #ifdef TRGM_REGEXP_DEBUG
614 : printTrgmPackedGraph(*graph, trg);
615 : #endif
616 :
617 53 : return trg;
618 : }
619 :
620 : /*
621 : * Main entry point for evaluating a graph during index scanning.
622 : *
623 : * The check[] array is indexed by trigram number (in the array of simple
624 : * trigrams returned by createTrgmNFA), and holds true for those trigrams
625 : * that are present in the index entry being checked.
626 : */
627 : bool
628 3561 : trigramsMatchGraph(TrgmPackedGraph *graph, bool *check)
629 : {
630 : int i,
631 : j,
632 : k,
633 : queueIn,
634 : queueOut;
635 :
636 : /*
637 : * Reset temporary working areas.
638 : */
639 3561 : memset(graph->colorTrigramsActive, 0,
640 3561 : sizeof(bool) * graph->colorTrigramsCount);
641 3561 : memset(graph->statesActive, 0, sizeof(bool) * graph->statesCount);
642 :
643 : /*
644 : * Check which color trigrams were matched. A match for any simple
645 : * trigram associated with a color trigram counts as a match of the color
646 : * trigram.
647 : */
648 3561 : j = 0;
649 11051 : for (i = 0; i < graph->colorTrigramsCount; i++)
650 : {
651 7490 : int cnt = graph->colorTrigramGroups[i];
652 :
653 166825 : for (k = j; k < j + cnt; k++)
654 : {
655 163195 : if (check[k])
656 : {
657 : /*
658 : * Found one matched trigram in the group. Can skip the rest
659 : * of them and go to the next group.
660 : */
661 3860 : graph->colorTrigramsActive[i] = true;
662 3860 : break;
663 : }
664 : }
665 7490 : j = j + cnt;
666 : }
667 :
668 : /*
669 : * Initialize the statesQueue to hold just the initial state. Note:
670 : * statesQueue has room for statesCount entries, which is certainly enough
671 : * since no state will be put in the queue more than once. The
672 : * statesActive array marks which states have been queued.
673 : */
674 3561 : graph->statesActive[0] = true;
675 3561 : graph->statesQueue[0] = 0;
676 3561 : queueIn = 0;
677 3561 : queueOut = 1;
678 :
679 : /* Process queued states as long as there are any. */
680 7661 : while (queueIn < queueOut)
681 : {
682 7525 : int stateno = graph->statesQueue[queueIn++];
683 7525 : TrgmPackedState *state = &graph->states[stateno];
684 7525 : int cnt = state->arcsCount;
685 :
686 : /* Loop over state's out-arcs */
687 15164 : for (i = 0; i < cnt; i++)
688 : {
689 11064 : TrgmPackedArc *arc = &state->arcs[i];
690 :
691 : /*
692 : * If corresponding color trigram is present then activate the
693 : * corresponding state. We're done if that's the final state,
694 : * otherwise queue the state if it's not been queued already.
695 : */
696 11064 : if (graph->colorTrigramsActive[arc->colorTrgm])
697 : {
698 7732 : int nextstate = arc->targetState;
699 :
700 7732 : if (nextstate == 1)
701 3425 : return true; /* success: final state is reachable */
702 :
703 4307 : if (!graph->statesActive[nextstate])
704 : {
705 4250 : graph->statesActive[nextstate] = true;
706 4250 : graph->statesQueue[queueOut++] = nextstate;
707 : }
708 : }
709 : }
710 : }
711 :
712 : /* Queue is empty, so match fails. */
713 136 : return false;
714 : }
715 :
716 : /*
717 : * Compile regex string into struct at *regex.
718 : * NB: pg_regfree must be applied to regex if this completes successfully.
719 : */
720 : static void
721 65 : RE_compile(regex_t *regex, text *text_re, int cflags, Oid collation)
722 : {
723 65 : int text_re_len = VARSIZE_ANY_EXHDR(text_re);
724 65 : char *text_re_val = VARDATA_ANY(text_re);
725 : pg_wchar *pattern;
726 : int pattern_len;
727 : int regcomp_result;
728 : char errMsg[100];
729 :
730 : /* Convert pattern string to wide characters */
731 65 : pattern = (pg_wchar *) palloc((text_re_len + 1) * sizeof(pg_wchar));
732 65 : pattern_len = pg_mb2wchar_with_len(text_re_val,
733 : pattern,
734 : text_re_len);
735 :
736 : /* Compile regex */
737 65 : regcomp_result = pg_regcomp(regex,
738 : pattern,
739 : pattern_len,
740 : cflags,
741 : collation);
742 :
743 65 : pfree(pattern);
744 :
745 65 : if (regcomp_result != REG_OKAY)
746 : {
747 : /* re didn't compile (no need for pg_regfree, if so) */
748 0 : pg_regerror(regcomp_result, regex, errMsg, sizeof(errMsg));
749 0 : ereport(ERROR,
750 : (errcode(ERRCODE_INVALID_REGULAR_EXPRESSION),
751 : errmsg("invalid regular expression: %s", errMsg)));
752 : }
753 65 : }
754 :
755 :
756 : /*---------------------
757 : * Subroutines for pre-processing the color map (stage 1).
758 : *---------------------
759 : */
760 :
761 : /*
762 : * Fill TrgmColorInfo structure for each color using regex export functions.
763 : */
764 : static void
765 65 : getColorInfo(regex_t *regex, TrgmNFA *trgmNFA)
766 : {
767 65 : int colorsCount = pg_reg_getnumcolors(regex);
768 : int i;
769 :
770 65 : trgmNFA->ncolors = colorsCount;
771 65 : trgmNFA->colorInfo = (TrgmColorInfo *)
772 65 : palloc0(colorsCount * sizeof(TrgmColorInfo));
773 :
774 : /*
775 : * Loop over colors, filling TrgmColorInfo about each. Note we include
776 : * WHITE (0) even though we know it'll be reported as non-expandable.
777 : */
778 596 : for (i = 0; i < colorsCount; i++)
779 : {
780 531 : TrgmColorInfo *colorInfo = &trgmNFA->colorInfo[i];
781 531 : int charsCount = pg_reg_getnumcharacters(regex, i);
782 : pg_wchar *chars;
783 : int j;
784 :
785 531 : if (charsCount < 0 || charsCount > COLOR_COUNT_LIMIT)
786 : {
787 : /* Non expandable, or too large to work with */
788 325 : colorInfo->expandable = false;
789 325 : continue;
790 : }
791 :
792 206 : colorInfo->expandable = true;
793 206 : colorInfo->containsNonWord = false;
794 206 : colorInfo->wordChars = palloc_array(trgm_mb_char, charsCount);
795 206 : colorInfo->wordCharsCount = 0;
796 :
797 : /* Extract all the chars in this color */
798 206 : chars = palloc_array(pg_wchar, charsCount);
799 206 : pg_reg_getcharacters(regex, i, chars, charsCount);
800 :
801 : /*
802 : * Convert characters back to multibyte form, and save only those that
803 : * are word characters. Set "containsNonWord" if any non-word
804 : * character. (Note: it'd probably be nicer to keep the chars in
805 : * pg_wchar format for now, but ISWORDCHR wants to see multibyte.)
806 : */
807 991 : for (j = 0; j < charsCount; j++)
808 : {
809 : trgm_mb_char c;
810 785 : int clen = convertPgWchar(chars[j], &c);
811 :
812 785 : if (!clen)
813 365 : continue; /* ok to ignore it altogether */
814 420 : if (ISWORDCHR(c.bytes, clen))
815 395 : colorInfo->wordChars[colorInfo->wordCharsCount++] = c;
816 : else
817 25 : colorInfo->containsNonWord = true;
818 : }
819 :
820 206 : pfree(chars);
821 : }
822 65 : }
823 :
824 : /*
825 : * Convert pg_wchar to multibyte format.
826 : * Returns 0 if the character should be ignored completely, else returns its
827 : * byte length.
828 : */
829 : static int
830 785 : convertPgWchar(pg_wchar c, trgm_mb_char *result)
831 : {
832 : /* "s" has enough space for a multibyte character and a trailing NUL */
833 : char s[MAX_MULTIBYTE_CHAR_LEN + 1];
834 : int clen;
835 :
836 : /*
837 : * We can ignore the NUL character, since it can never appear in a PG text
838 : * string. This avoids the need for various special cases when
839 : * reconstructing trigrams.
840 : */
841 785 : if (c == 0)
842 0 : return 0;
843 :
844 : /* Do the conversion, making sure the result is NUL-terminated */
845 785 : memset(s, 0, sizeof(s));
846 785 : clen = pg_wchar2mb_with_len(&c, s, 1);
847 :
848 : /*
849 : * In IGNORECASE mode, we can ignore uppercase characters. We assume that
850 : * the regex engine generated both uppercase and lowercase equivalents
851 : * within each color, since we used the REG_ICASE option; so there's no
852 : * need to process the uppercase version.
853 : *
854 : * XXX this code is dependent on the assumption that str_tolower() works
855 : * the same as the regex engine's internal case folding machinery. Might
856 : * be wiser to expose pg_wc_tolower and test whether c ==
857 : * pg_wc_tolower(c). On the other hand, the trigrams in the index were
858 : * created using str_tolower(), so we're probably screwed if there's any
859 : * incompatibility anyway.
860 : */
861 : #ifdef IGNORECASE
862 : {
863 785 : char *lowerCased = str_tolower(s, clen, DEFAULT_COLLATION_OID);
864 :
865 785 : if (strcmp(lowerCased, s) != 0)
866 : {
867 365 : pfree(lowerCased);
868 365 : return 0;
869 : }
870 420 : pfree(lowerCased);
871 : }
872 : #endif
873 :
874 : /* Fill result with exactly MAX_MULTIBYTE_CHAR_LEN bytes */
875 420 : memcpy(result->bytes, s, MAX_MULTIBYTE_CHAR_LEN);
876 420 : return clen;
877 : }
878 :
879 :
880 : /*---------------------
881 : * Subroutines for expanding original NFA graph into a trigram graph (stage 2).
882 : *---------------------
883 : */
884 :
885 : /*
886 : * Transform the graph, given a regex and extracted color information.
887 : *
888 : * We create and process a queue of expanded-graph states until all the states
889 : * are processed.
890 : *
891 : * This algorithm may be stopped due to resource limitation. In this case we
892 : * force every unprocessed branch to immediately finish with matching (this
893 : * can give us false positives but no false negatives) by marking all
894 : * unprocessed states as final.
895 : */
896 : static void
897 65 : transformGraph(TrgmNFA *trgmNFA)
898 : {
899 : HASHCTL hashCtl;
900 : TrgmStateKey initkey;
901 : TrgmState *initstate;
902 : ListCell *lc;
903 :
904 : /* Initialize this stage's workspace in trgmNFA struct */
905 65 : trgmNFA->queue = NIL;
906 65 : trgmNFA->keysQueue = NIL;
907 65 : trgmNFA->arcsCount = 0;
908 65 : trgmNFA->overflowed = false;
909 :
910 : /* Create hashtable for states */
911 65 : hashCtl.keysize = sizeof(TrgmStateKey);
912 65 : hashCtl.entrysize = sizeof(TrgmState);
913 65 : hashCtl.hcxt = CurrentMemoryContext;
914 65 : trgmNFA->states = hash_create("Trigram NFA",
915 : 1024,
916 : &hashCtl,
917 : HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
918 65 : trgmNFA->nstates = 0;
919 :
920 : /* Create initial state: ambiguous prefix, NFA's initial state */
921 65 : MemSet(&initkey, 0, sizeof(initkey));
922 65 : initkey.prefix.colors[0] = COLOR_UNKNOWN;
923 65 : initkey.prefix.colors[1] = COLOR_UNKNOWN;
924 65 : initkey.nstate = pg_reg_getinitialstate(trgmNFA->regex);
925 :
926 65 : initstate = getState(trgmNFA, &initkey);
927 65 : initstate->flags |= TSTATE_INIT;
928 65 : trgmNFA->initState = initstate;
929 :
930 : /*
931 : * Recursively build the expanded graph by processing queue of states
932 : * (breadth-first search). getState already put initstate in the queue.
933 : * Note that getState will append new states to the queue within the loop,
934 : * too; this works as long as we don't do repeat fetches using the "lc"
935 : * pointer.
936 : */
937 729 : foreach(lc, trgmNFA->queue)
938 : {
939 664 : TrgmState *state = (TrgmState *) lfirst(lc);
940 :
941 : /*
942 : * If we overflowed then just mark state as final. Otherwise do
943 : * actual processing.
944 : */
945 664 : if (trgmNFA->overflowed)
946 9 : state->flags |= TSTATE_FIN;
947 : else
948 655 : processState(trgmNFA, state);
949 :
950 : /* Did we overflow? */
951 1328 : if (trgmNFA->arcsCount > MAX_EXPANDED_ARCS ||
952 664 : hash_get_num_entries(trgmNFA->states) > MAX_EXPANDED_STATES)
953 12 : trgmNFA->overflowed = true;
954 : }
955 65 : }
956 :
957 : /*
958 : * Process one state: add enter keys and then add outgoing arcs.
959 : */
960 : static void
961 655 : processState(TrgmNFA *trgmNFA, TrgmState *state)
962 : {
963 : ListCell *lc;
964 :
965 : /* keysQueue should be NIL already, but make sure */
966 655 : trgmNFA->keysQueue = NIL;
967 :
968 : /*
969 : * Add state's own key, and then process all keys added to keysQueue until
970 : * queue is finished. But we can quit if the state gets marked final.
971 : */
972 655 : addKey(trgmNFA, state, &state->stateKey);
973 1266 : foreach(lc, trgmNFA->keysQueue)
974 : {
975 692 : TrgmStateKey *key = (TrgmStateKey *) lfirst(lc);
976 :
977 692 : if (state->flags & TSTATE_FIN)
978 81 : break;
979 611 : addKey(trgmNFA, state, key);
980 : }
981 :
982 : /* Release keysQueue to clean up for next cycle */
983 655 : list_free(trgmNFA->keysQueue);
984 655 : trgmNFA->keysQueue = NIL;
985 :
986 : /*
987 : * Add outgoing arcs only if state isn't final (we have no interest in
988 : * outgoing arcs if we already match)
989 : */
990 655 : if (!(state->flags & TSTATE_FIN))
991 571 : addArcs(trgmNFA, state);
992 655 : }
993 :
994 : /*
995 : * Add the given enter key into the state's enterKeys list, and determine
996 : * whether this should result in any further enter keys being added.
997 : * If so, add those keys to keysQueue so that processState will handle them.
998 : *
999 : * If the enter key is for the NFA's final state, mark state as TSTATE_FIN.
1000 : * This situation means that we can reach the final state from this expanded
1001 : * state without reading any predictable trigram, so we must consider this
1002 : * state as an accepting one.
1003 : *
1004 : * The given key could be a duplicate of one already in enterKeys, or be
1005 : * redundant with some enterKeys. So we check that before doing anything.
1006 : *
1007 : * Note that we don't generate any actual arcs here. addArcs will do that
1008 : * later, after we have identified all the enter keys for this state.
1009 : */
1010 : static void
1011 1266 : addKey(TrgmNFA *trgmNFA, TrgmState *state, TrgmStateKey *key)
1012 : {
1013 : regex_arc_t *arcs;
1014 : TrgmStateKey destKey;
1015 : ListCell *cell;
1016 : int i,
1017 : arcsCount;
1018 :
1019 : /*
1020 : * Ensure any pad bytes in destKey are zero, since it may get used as a
1021 : * hashtable key by getState.
1022 : */
1023 1266 : MemSet(&destKey, 0, sizeof(destKey));
1024 :
1025 : /*
1026 : * Compare key to each existing enter key of the state to check for
1027 : * redundancy. We can drop either old key(s) or the new key if we find
1028 : * redundancy.
1029 : */
1030 1979 : foreach(cell, state->enterKeys)
1031 : {
1032 1016 : TrgmStateKey *existingKey = (TrgmStateKey *) lfirst(cell);
1033 :
1034 1016 : if (existingKey->nstate == key->nstate)
1035 : {
1036 312 : if (prefixContains(&existingKey->prefix, &key->prefix))
1037 : {
1038 : /* This old key already covers the new key. Nothing to do */
1039 303 : return;
1040 : }
1041 9 : if (prefixContains(&key->prefix, &existingKey->prefix))
1042 : {
1043 : /*
1044 : * The new key covers this old key. Remove the old key, it's
1045 : * no longer needed once we add this key to the list.
1046 : */
1047 6 : state->enterKeys = foreach_delete_current(state->enterKeys,
1048 : cell);
1049 : }
1050 : }
1051 : }
1052 :
1053 : /* No redundancy, so add this key to the state's list */
1054 963 : state->enterKeys = lappend(state->enterKeys, key);
1055 :
1056 : /* If state is now known final, mark it and we're done */
1057 963 : if (key->nstate == pg_reg_getfinalstate(trgmNFA->regex))
1058 : {
1059 84 : state->flags |= TSTATE_FIN;
1060 84 : return;
1061 : }
1062 :
1063 : /*
1064 : * Loop through all outgoing arcs of the corresponding state in the
1065 : * original NFA.
1066 : */
1067 879 : arcsCount = pg_reg_getnumoutarcs(trgmNFA->regex, key->nstate);
1068 879 : arcs = palloc_array(regex_arc_t, arcsCount);
1069 879 : pg_reg_getoutarcs(trgmNFA->regex, key->nstate, arcs, arcsCount);
1070 :
1071 2384 : for (i = 0; i < arcsCount; i++)
1072 : {
1073 1505 : regex_arc_t *arc = &arcs[i];
1074 :
1075 1505 : if (pg_reg_colorisbegin(trgmNFA->regex, arc->co))
1076 : {
1077 : /*
1078 : * Start of line/string (^). Trigram extraction treats start of
1079 : * line same as start of word: double space prefix is added.
1080 : * Hence, make an enter key showing we can reach the arc
1081 : * destination with all-blank prefix.
1082 : */
1083 246 : destKey.prefix.colors[0] = COLOR_BLANK;
1084 246 : destKey.prefix.colors[1] = COLOR_BLANK;
1085 246 : destKey.nstate = arc->to;
1086 :
1087 : /* Add enter key to this state */
1088 246 : addKeyToQueue(trgmNFA, &destKey);
1089 : }
1090 1259 : else if (pg_reg_colorisend(trgmNFA->regex, arc->co))
1091 : {
1092 : /*
1093 : * End of line/string ($). We must consider this arc as a
1094 : * transition that doesn't read anything. The reason for adding
1095 : * this enter key to the state is that if the arc leads to the
1096 : * NFA's final state, we must mark this expanded state as final.
1097 : */
1098 162 : destKey.prefix.colors[0] = COLOR_UNKNOWN;
1099 162 : destKey.prefix.colors[1] = COLOR_UNKNOWN;
1100 162 : destKey.nstate = arc->to;
1101 :
1102 : /* Add enter key to this state */
1103 162 : addKeyToQueue(trgmNFA, &destKey);
1104 : }
1105 1097 : else if (arc->co >= 0)
1106 : {
1107 : /* Regular color (including WHITE) */
1108 893 : TrgmColorInfo *colorInfo = &trgmNFA->colorInfo[arc->co];
1109 :
1110 893 : if (colorInfo->expandable)
1111 : {
1112 893 : if (colorInfo->containsNonWord &&
1113 55 : !validArcLabel(key, COLOR_BLANK))
1114 : {
1115 : /*
1116 : * We can reach the arc destination after reading a
1117 : * non-word character, but the prefix is not something
1118 : * that addArc will accept with COLOR_BLANK, so no trigram
1119 : * arc can get made for this transition. We must make an
1120 : * enter key to show that the arc destination is
1121 : * reachable. Set it up with an all-blank prefix, since
1122 : * that corresponds to what the trigram extraction code
1123 : * will do at a word starting boundary.
1124 : */
1125 27 : destKey.prefix.colors[0] = COLOR_BLANK;
1126 27 : destKey.prefix.colors[1] = COLOR_BLANK;
1127 27 : destKey.nstate = arc->to;
1128 27 : addKeyToQueue(trgmNFA, &destKey);
1129 : }
1130 :
1131 893 : if (colorInfo->wordCharsCount > 0 &&
1132 838 : !validArcLabel(key, arc->co))
1133 : {
1134 : /*
1135 : * We can reach the arc destination after reading a word
1136 : * character, but the prefix is not something that addArc
1137 : * will accept, so no trigram arc can get made for this
1138 : * transition. We must make an enter key to show that the
1139 : * arc destination is reachable. The prefix for the enter
1140 : * key should reflect the info we have for this arc.
1141 : */
1142 131 : destKey.prefix.colors[0] = key->prefix.colors[1];
1143 131 : destKey.prefix.colors[1] = arc->co;
1144 131 : destKey.nstate = arc->to;
1145 131 : addKeyToQueue(trgmNFA, &destKey);
1146 : }
1147 : }
1148 : else
1149 : {
1150 : /*
1151 : * Unexpandable color. Add enter key with ambiguous prefix,
1152 : * showing we can reach the destination from this state, but
1153 : * the preceding colors will be uncertain. (We do not set the
1154 : * first prefix color to key->prefix.colors[1], because a
1155 : * prefix of known followed by unknown is invalid.)
1156 : */
1157 0 : destKey.prefix.colors[0] = COLOR_UNKNOWN;
1158 0 : destKey.prefix.colors[1] = COLOR_UNKNOWN;
1159 0 : destKey.nstate = arc->to;
1160 0 : addKeyToQueue(trgmNFA, &destKey);
1161 : }
1162 : }
1163 : else
1164 : {
1165 : /* RAINBOW: treat as unexpandable color */
1166 204 : destKey.prefix.colors[0] = COLOR_UNKNOWN;
1167 204 : destKey.prefix.colors[1] = COLOR_UNKNOWN;
1168 204 : destKey.nstate = arc->to;
1169 204 : addKeyToQueue(trgmNFA, &destKey);
1170 : }
1171 : }
1172 :
1173 879 : pfree(arcs);
1174 : }
1175 :
1176 : /*
1177 : * Add copy of given key to keysQueue for later processing.
1178 : */
1179 : static void
1180 770 : addKeyToQueue(TrgmNFA *trgmNFA, TrgmStateKey *key)
1181 : {
1182 770 : TrgmStateKey *keyCopy = palloc_object(TrgmStateKey);
1183 :
1184 770 : memcpy(keyCopy, key, sizeof(TrgmStateKey));
1185 770 : trgmNFA->keysQueue = lappend(trgmNFA->keysQueue, keyCopy);
1186 770 : }
1187 :
1188 : /*
1189 : * Add outgoing arcs from given state, whose enter keys are all now known.
1190 : */
1191 : static void
1192 571 : addArcs(TrgmNFA *trgmNFA, TrgmState *state)
1193 : {
1194 : TrgmStateKey destKey;
1195 : ListCell *cell;
1196 : regex_arc_t *arcs;
1197 : int arcsCount,
1198 : i;
1199 :
1200 : /*
1201 : * Ensure any pad bytes in destKey are zero, since it may get used as a
1202 : * hashtable key by getState.
1203 : */
1204 571 : MemSet(&destKey, 0, sizeof(destKey));
1205 :
1206 : /*
1207 : * Iterate over enter keys associated with this expanded-graph state. This
1208 : * includes both the state's own stateKey, and any enter keys we added to
1209 : * it during addKey (which represent expanded-graph states that are not
1210 : * distinguishable from this one by means of trigrams). For each such
1211 : * enter key, examine all the out-arcs of the key's underlying NFA state,
1212 : * and try to make a trigram arc leading to where the out-arc leads.
1213 : * (addArc will deal with whether the arc is valid or not.)
1214 : */
1215 1336 : foreach(cell, state->enterKeys)
1216 : {
1217 765 : TrgmStateKey *key = (TrgmStateKey *) lfirst(cell);
1218 :
1219 765 : arcsCount = pg_reg_getnumoutarcs(trgmNFA->regex, key->nstate);
1220 765 : arcs = palloc_array(regex_arc_t, arcsCount);
1221 765 : pg_reg_getoutarcs(trgmNFA->regex, key->nstate, arcs, arcsCount);
1222 :
1223 1946 : for (i = 0; i < arcsCount; i++)
1224 : {
1225 1181 : regex_arc_t *arc = &arcs[i];
1226 : TrgmColorInfo *colorInfo;
1227 :
1228 : /*
1229 : * Ignore non-expandable colors; addKey already handled the case.
1230 : *
1231 : * We need no special check for WHITE or begin/end pseudocolors
1232 : * here. We don't need to do any processing for them, and they
1233 : * will be marked non-expandable since the regex engine will have
1234 : * reported them that way. We do have to watch out for RAINBOW,
1235 : * which has a negative color number.
1236 : */
1237 1181 : if (arc->co < 0)
1238 102 : continue;
1239 : Assert(arc->co < trgmNFA->ncolors);
1240 :
1241 1079 : colorInfo = &trgmNFA->colorInfo[arc->co];
1242 1079 : if (!colorInfo->expandable)
1243 210 : continue;
1244 :
1245 869 : if (colorInfo->containsNonWord)
1246 : {
1247 : /*
1248 : * Color includes non-word character(s).
1249 : *
1250 : * Generate an arc, treating this transition as occurring on
1251 : * BLANK. This allows word-ending trigrams to be manufactured
1252 : * if possible.
1253 : */
1254 55 : destKey.prefix.colors[0] = key->prefix.colors[1];
1255 55 : destKey.prefix.colors[1] = COLOR_BLANK;
1256 55 : destKey.nstate = arc->to;
1257 :
1258 55 : addArc(trgmNFA, state, key, COLOR_BLANK, &destKey);
1259 : }
1260 :
1261 869 : if (colorInfo->wordCharsCount > 0)
1262 : {
1263 : /*
1264 : * Color includes word character(s).
1265 : *
1266 : * Generate an arc. Color is pushed into prefix of target
1267 : * state.
1268 : */
1269 814 : destKey.prefix.colors[0] = key->prefix.colors[1];
1270 814 : destKey.prefix.colors[1] = arc->co;
1271 814 : destKey.nstate = arc->to;
1272 :
1273 814 : addArc(trgmNFA, state, key, arc->co, &destKey);
1274 : }
1275 : }
1276 :
1277 765 : pfree(arcs);
1278 : }
1279 571 : }
1280 :
1281 : /*
1282 : * Generate an out-arc of the expanded graph, if it's valid and not redundant.
1283 : *
1284 : * state: expanded-graph state we want to add an out-arc to
1285 : * key: provides prefix colors (key->nstate is not used)
1286 : * co: transition color
1287 : * destKey: identifier for destination state of expanded graph
1288 : */
1289 : static void
1290 869 : addArc(TrgmNFA *trgmNFA, TrgmState *state, TrgmStateKey *key,
1291 : TrgmColor co, TrgmStateKey *destKey)
1292 : {
1293 : TrgmArc *arc;
1294 : ListCell *cell;
1295 :
1296 : /* Do nothing if this wouldn't be a valid arc label trigram */
1297 869 : if (!validArcLabel(key, co))
1298 137 : return;
1299 :
1300 : /*
1301 : * Check if we are going to reach key which is covered by a key which is
1302 : * already listed in this state. If so arc is useless: the NFA can bypass
1303 : * it through a path that doesn't require any predictable trigram, so
1304 : * whether the arc's trigram is present or not doesn't really matter.
1305 : */
1306 1767 : foreach(cell, state->enterKeys)
1307 : {
1308 1041 : TrgmStateKey *existingKey = (TrgmStateKey *) lfirst(cell);
1309 :
1310 1066 : if (existingKey->nstate == destKey->nstate &&
1311 25 : prefixContains(&existingKey->prefix, &destKey->prefix))
1312 6 : return;
1313 : }
1314 :
1315 : /* Checks were successful, add new arc */
1316 726 : arc = palloc_object(TrgmArc);
1317 726 : arc->target = getState(trgmNFA, destKey);
1318 726 : arc->ctrgm.colors[0] = key->prefix.colors[0];
1319 726 : arc->ctrgm.colors[1] = key->prefix.colors[1];
1320 726 : arc->ctrgm.colors[2] = co;
1321 :
1322 726 : state->arcs = lappend(state->arcs, arc);
1323 726 : trgmNFA->arcsCount++;
1324 : }
1325 :
1326 : /*
1327 : * Can we make a valid trigram arc label from the given prefix and arc color?
1328 : *
1329 : * This is split out so that tests in addKey and addArc will stay in sync.
1330 : */
1331 : static bool
1332 1762 : validArcLabel(TrgmStateKey *key, TrgmColor co)
1333 : {
1334 : /*
1335 : * We have to know full trigram in order to add outgoing arc. So we can't
1336 : * do it if prefix is ambiguous.
1337 : */
1338 1762 : if (key->prefix.colors[0] == COLOR_UNKNOWN)
1339 233 : return false;
1340 :
1341 : /* If key->prefix.colors[0] isn't unknown, its second color isn't either */
1342 : Assert(key->prefix.colors[1] != COLOR_UNKNOWN);
1343 : /* And we should not be called with an unknown arc color anytime */
1344 : Assert(co != COLOR_UNKNOWN);
1345 :
1346 : /*
1347 : * We don't bother with making arcs representing three non-word
1348 : * characters, since that's useless for trigram extraction.
1349 : */
1350 1529 : if (key->prefix.colors[0] == COLOR_BLANK &&
1351 164 : key->prefix.colors[1] == COLOR_BLANK &&
1352 : co == COLOR_BLANK)
1353 12 : return false;
1354 :
1355 : /*
1356 : * We also reject nonblank-blank-anything. The nonblank-blank-nonblank
1357 : * case doesn't correspond to any trigram the trigram extraction code
1358 : * would make. The nonblank-blank-blank case is also not possible with
1359 : * RPADDING = 1. (Note that in many cases we'd fail to generate such a
1360 : * trigram even if it were valid, for example processing "foo bar" will
1361 : * not result in considering the trigram "o ". So if you want to support
1362 : * RPADDING = 2, there's more to do than just twiddle this test.)
1363 : */
1364 1517 : if (key->prefix.colors[0] != COLOR_BLANK &&
1365 1365 : key->prefix.colors[1] == COLOR_BLANK)
1366 50 : return false;
1367 :
1368 : /*
1369 : * Other combinations involving blank are valid, in particular we assume
1370 : * blank-blank-nonblank is valid, which presumes that LPADDING is 2.
1371 : *
1372 : * Note: Using again the example "foo bar", we will not consider the
1373 : * trigram " b", though this trigram would be found by the trigram
1374 : * extraction code. Since we will find " ba", it doesn't seem worth
1375 : * trying to hack the algorithm to generate the additional trigram.
1376 : */
1377 :
1378 : /* arc label is valid */
1379 1467 : return true;
1380 : }
1381 :
1382 : /*
1383 : * Get state of expanded graph for given state key,
1384 : * and queue the state for processing if it didn't already exist.
1385 : */
1386 : static TrgmState *
1387 791 : getState(TrgmNFA *trgmNFA, TrgmStateKey *key)
1388 : {
1389 : TrgmState *state;
1390 : bool found;
1391 :
1392 791 : state = (TrgmState *) hash_search(trgmNFA->states, key, HASH_ENTER,
1393 : &found);
1394 791 : if (!found)
1395 : {
1396 : /* New state: initialize and queue it */
1397 664 : state->arcs = NIL;
1398 664 : state->enterKeys = NIL;
1399 664 : state->flags = 0;
1400 : /* states are initially given negative numbers */
1401 664 : state->snumber = -(++trgmNFA->nstates);
1402 664 : state->parent = NULL;
1403 664 : state->tentFlags = 0;
1404 664 : state->tentParent = NULL;
1405 :
1406 664 : trgmNFA->queue = lappend(trgmNFA->queue, state);
1407 : }
1408 791 : return state;
1409 : }
1410 :
1411 : /*
1412 : * Check if prefix1 "contains" prefix2.
1413 : *
1414 : * "contains" means that any exact prefix (with no ambiguity) that satisfies
1415 : * prefix2 also satisfies prefix1.
1416 : */
1417 : static bool
1418 346 : prefixContains(TrgmPrefix *prefix1, TrgmPrefix *prefix2)
1419 : {
1420 346 : if (prefix1->colors[1] == COLOR_UNKNOWN)
1421 : {
1422 : /* Fully ambiguous prefix contains everything */
1423 306 : return true;
1424 : }
1425 40 : else if (prefix1->colors[0] == COLOR_UNKNOWN)
1426 : {
1427 : /*
1428 : * Prefix with only first unknown color contains every prefix with
1429 : * same second color.
1430 : */
1431 12 : if (prefix1->colors[1] == prefix2->colors[1])
1432 3 : return true;
1433 : else
1434 9 : return false;
1435 : }
1436 : else
1437 : {
1438 : /* Exact prefix contains only the exact same prefix */
1439 28 : if (prefix1->colors[0] == prefix2->colors[0] &&
1440 13 : prefix1->colors[1] == prefix2->colors[1])
1441 6 : return true;
1442 : else
1443 22 : return false;
1444 : }
1445 : }
1446 :
1447 :
1448 : /*---------------------
1449 : * Subroutines for expanding color trigrams into regular trigrams (stage 3).
1450 : *---------------------
1451 : */
1452 :
1453 : /*
1454 : * Get vector of all color trigrams in graph and select which of them
1455 : * to expand into simple trigrams.
1456 : *
1457 : * Returns true if OK, false if exhausted resource limits.
1458 : */
1459 : static bool
1460 56 : selectColorTrigrams(TrgmNFA *trgmNFA)
1461 : {
1462 : HASH_SEQ_STATUS scan_status;
1463 56 : int arcsCount = trgmNFA->arcsCount,
1464 : i;
1465 : TrgmState *state;
1466 : ColorTrgmInfo *colorTrgms;
1467 : int64 totalTrgmCount;
1468 : float4 totalTrgmPenalty;
1469 : int cnumber;
1470 :
1471 : /* Collect color trigrams from all arcs */
1472 56 : colorTrgms = palloc0_array(ColorTrgmInfo, arcsCount);
1473 56 : trgmNFA->colorTrgms = colorTrgms;
1474 :
1475 56 : i = 0;
1476 56 : hash_seq_init(&scan_status, trgmNFA->states);
1477 711 : while ((state = (TrgmState *) hash_seq_search(&scan_status)) != NULL)
1478 : {
1479 : ListCell *cell;
1480 :
1481 1381 : foreach(cell, state->arcs)
1482 : {
1483 726 : TrgmArc *arc = (TrgmArc *) lfirst(cell);
1484 726 : TrgmArcInfo *arcInfo = palloc_object(TrgmArcInfo);
1485 726 : ColorTrgmInfo *trgmInfo = &colorTrgms[i];
1486 :
1487 726 : arcInfo->source = state;
1488 726 : arcInfo->target = arc->target;
1489 726 : trgmInfo->ctrgm = arc->ctrgm;
1490 726 : trgmInfo->cnumber = -1;
1491 : /* count and penalty will be set below */
1492 726 : trgmInfo->expanded = true;
1493 726 : trgmInfo->arcs = list_make1(arcInfo);
1494 726 : i++;
1495 : }
1496 : }
1497 : Assert(i == arcsCount);
1498 :
1499 : /* Remove duplicates, merging their arcs lists */
1500 56 : if (arcsCount >= 2)
1501 : {
1502 : ColorTrgmInfo *p1,
1503 : *p2;
1504 :
1505 : /* Sort trigrams to ease duplicate detection */
1506 34 : qsort(colorTrgms, arcsCount, sizeof(ColorTrgmInfo), colorTrgmInfoCmp);
1507 :
1508 : /* p1 is probe point, p2 is last known non-duplicate. */
1509 34 : p2 = colorTrgms;
1510 706 : for (p1 = colorTrgms + 1; p1 < colorTrgms + arcsCount; p1++)
1511 : {
1512 672 : if (colorTrgmInfoCmp(p1, p2) > 0)
1513 : {
1514 224 : p2++;
1515 224 : *p2 = *p1;
1516 : }
1517 : else
1518 : {
1519 448 : p2->arcs = list_concat(p2->arcs, p1->arcs);
1520 : }
1521 : }
1522 34 : trgmNFA->colorTrgmsCount = (p2 - colorTrgms) + 1;
1523 : }
1524 : else
1525 : {
1526 22 : trgmNFA->colorTrgmsCount = arcsCount;
1527 : }
1528 :
1529 : /*
1530 : * Count number of simple trigrams generated by each color trigram, and
1531 : * also compute a penalty value, which is the number of simple trigrams
1532 : * times a multiplier that depends on its whitespace content.
1533 : *
1534 : * Note: per-color-trigram counts cannot overflow an int so long as
1535 : * COLOR_COUNT_LIMIT is not more than the cube root of INT_MAX, ie about
1536 : * 1290. However, the grand total totalTrgmCount might conceivably
1537 : * overflow an int, so we use int64 for that within this routine. Also,
1538 : * penalties are calculated in float4 arithmetic to avoid any overflow
1539 : * worries.
1540 : */
1541 56 : totalTrgmCount = 0;
1542 56 : totalTrgmPenalty = 0.0f;
1543 334 : for (i = 0; i < trgmNFA->colorTrgmsCount; i++)
1544 : {
1545 278 : ColorTrgmInfo *trgmInfo = &colorTrgms[i];
1546 : int j,
1547 278 : count = 1,
1548 278 : typeIndex = 0;
1549 :
1550 1112 : for (j = 0; j < 3; j++)
1551 : {
1552 834 : TrgmColor c = trgmInfo->ctrgm.colors[j];
1553 :
1554 834 : typeIndex *= 2;
1555 834 : if (c == COLOR_BLANK)
1556 113 : typeIndex++;
1557 : else
1558 721 : count *= trgmNFA->colorInfo[c].wordCharsCount;
1559 : }
1560 278 : trgmInfo->count = count;
1561 278 : totalTrgmCount += count;
1562 278 : trgmInfo->penalty = penalties[typeIndex] * (float4) count;
1563 278 : totalTrgmPenalty += trgmInfo->penalty;
1564 : }
1565 :
1566 : /* Sort color trigrams in descending order of their penalties */
1567 56 : qsort(colorTrgms, trgmNFA->colorTrgmsCount, sizeof(ColorTrgmInfo),
1568 : colorTrgmInfoPenaltyCmp);
1569 :
1570 : /*
1571 : * Remove color trigrams from the graph so long as total penalty of color
1572 : * trigrams exceeds WISH_TRGM_PENALTY. (If we fail to get down to
1573 : * WISH_TRGM_PENALTY, it's OK so long as total count is no more than
1574 : * MAX_TRGM_COUNT.) We prefer to remove color trigrams with higher
1575 : * penalty, since those are the most promising for reducing the total
1576 : * penalty. When removing a color trigram we have to merge states
1577 : * connected by arcs labeled with that trigram. It's necessary to not
1578 : * merge initial and final states, because our graph becomes useless if
1579 : * that happens; so we cannot always remove the trigram we'd prefer to.
1580 : */
1581 204 : for (i = 0; i < trgmNFA->colorTrgmsCount; i++)
1582 : {
1583 179 : ColorTrgmInfo *trgmInfo = &colorTrgms[i];
1584 179 : bool canRemove = true;
1585 : ListCell *cell;
1586 :
1587 : /* Done if we've reached the target */
1588 179 : if (totalTrgmPenalty <= WISH_TRGM_PENALTY)
1589 31 : break;
1590 :
1591 : #ifdef TRGM_REGEXP_DEBUG
1592 : fprintf(stderr, "considering ctrgm %d %d %d, penalty %f, %d arcs\n",
1593 : trgmInfo->ctrgm.colors[0],
1594 : trgmInfo->ctrgm.colors[1],
1595 : trgmInfo->ctrgm.colors[2],
1596 : trgmInfo->penalty,
1597 : list_length(trgmInfo->arcs));
1598 : #endif
1599 :
1600 : /*
1601 : * Does any arc of this color trigram connect initial and final
1602 : * states? If so we can't remove it.
1603 : */
1604 306 : foreach(cell, trgmInfo->arcs)
1605 : {
1606 191 : TrgmArcInfo *arcInfo = (TrgmArcInfo *) lfirst(cell);
1607 191 : TrgmState *source = arcInfo->source,
1608 191 : *target = arcInfo->target;
1609 : int source_flags,
1610 : target_flags;
1611 :
1612 : #ifdef TRGM_REGEXP_DEBUG
1613 : fprintf(stderr, "examining arc to s%d (%x) from s%d (%x)\n",
1614 : -target->snumber, target->flags,
1615 : -source->snumber, source->flags);
1616 : #endif
1617 :
1618 : /* examine parent states, if any merging has already happened */
1619 341 : while (source->parent)
1620 150 : source = source->parent;
1621 407 : while (target->parent)
1622 216 : target = target->parent;
1623 :
1624 : #ifdef TRGM_REGEXP_DEBUG
1625 : fprintf(stderr, " ... after completed merges: to s%d (%x) from s%d (%x)\n",
1626 : -target->snumber, target->flags,
1627 : -source->snumber, source->flags);
1628 : #endif
1629 :
1630 : /* we must also consider merges we are planning right now */
1631 191 : source_flags = source->flags | source->tentFlags;
1632 195 : while (source->tentParent)
1633 : {
1634 4 : source = source->tentParent;
1635 4 : source_flags |= source->flags | source->tentFlags;
1636 : }
1637 191 : target_flags = target->flags | target->tentFlags;
1638 206 : while (target->tentParent)
1639 : {
1640 15 : target = target->tentParent;
1641 15 : target_flags |= target->flags | target->tentFlags;
1642 : }
1643 :
1644 : #ifdef TRGM_REGEXP_DEBUG
1645 : fprintf(stderr, " ... after tentative merges: to s%d (%x) from s%d (%x)\n",
1646 : -target->snumber, target_flags,
1647 : -source->snumber, source_flags);
1648 : #endif
1649 :
1650 : /* would fully-merged state have both INIT and FIN set? */
1651 191 : if (((source_flags | target_flags) & (TSTATE_INIT | TSTATE_FIN)) ==
1652 : (TSTATE_INIT | TSTATE_FIN))
1653 : {
1654 33 : canRemove = false;
1655 33 : break;
1656 : }
1657 :
1658 : /* ok so far, so remember planned merge */
1659 158 : if (source != target)
1660 : {
1661 : #ifdef TRGM_REGEXP_DEBUG
1662 : fprintf(stderr, " ... tentatively merging s%d into s%d\n",
1663 : -target->snumber, -source->snumber);
1664 : #endif
1665 113 : target->tentParent = source;
1666 113 : source->tentFlags |= target_flags;
1667 : }
1668 : }
1669 :
1670 : /*
1671 : * We must reset all the tentFlags/tentParent fields before
1672 : * continuing. tentFlags could only have become set in states that
1673 : * are the source or parent or tentative parent of one of the current
1674 : * arcs; likewise tentParent could only have become set in states that
1675 : * are the target or parent or tentative parent of one of the current
1676 : * arcs. There might be some overlap between those sets, but if we
1677 : * clear tentFlags in target states as well as source states, we
1678 : * should be okay even if we visit a state as target before visiting
1679 : * it as a source.
1680 : */
1681 348 : foreach(cell, trgmInfo->arcs)
1682 : {
1683 200 : TrgmArcInfo *arcInfo = (TrgmArcInfo *) lfirst(cell);
1684 200 : TrgmState *source = arcInfo->source,
1685 200 : *target = arcInfo->target;
1686 : TrgmState *ttarget;
1687 :
1688 : /* no need to touch previously-merged states */
1689 350 : while (source->parent)
1690 150 : source = source->parent;
1691 440 : while (target->parent)
1692 240 : target = target->parent;
1693 :
1694 406 : while (source)
1695 : {
1696 206 : source->tentFlags = 0;
1697 206 : source = source->tentParent;
1698 : }
1699 :
1700 313 : while ((ttarget = target->tentParent) != NULL)
1701 : {
1702 113 : target->tentParent = NULL;
1703 113 : target->tentFlags = 0; /* in case it was also a source */
1704 113 : target = ttarget;
1705 : }
1706 : }
1707 :
1708 : /* Now, move on if we can't drop this trigram */
1709 148 : if (!canRemove)
1710 : {
1711 : #ifdef TRGM_REGEXP_DEBUG
1712 : fprintf(stderr, " ... not ok to merge\n");
1713 : #endif
1714 33 : continue;
1715 : }
1716 :
1717 : /* OK, merge states linked by each arc labeled by the trigram */
1718 263 : foreach(cell, trgmInfo->arcs)
1719 : {
1720 148 : TrgmArcInfo *arcInfo = (TrgmArcInfo *) lfirst(cell);
1721 148 : TrgmState *source = arcInfo->source,
1722 148 : *target = arcInfo->target;
1723 :
1724 292 : while (source->parent)
1725 144 : source = source->parent;
1726 346 : while (target->parent)
1727 198 : target = target->parent;
1728 148 : if (source != target)
1729 : {
1730 : #ifdef TRGM_REGEXP_DEBUG
1731 : fprintf(stderr, "merging s%d into s%d\n",
1732 : -target->snumber, -source->snumber);
1733 : #endif
1734 103 : mergeStates(source, target);
1735 : /* Assert we didn't merge initial and final states */
1736 : Assert((source->flags & (TSTATE_INIT | TSTATE_FIN)) !=
1737 : (TSTATE_INIT | TSTATE_FIN));
1738 : }
1739 : }
1740 :
1741 : /* Mark trigram unexpanded, and update totals */
1742 115 : trgmInfo->expanded = false;
1743 115 : totalTrgmCount -= trgmInfo->count;
1744 115 : totalTrgmPenalty -= trgmInfo->penalty;
1745 : }
1746 :
1747 : /* Did we succeed in fitting into MAX_TRGM_COUNT? */
1748 56 : if (totalTrgmCount > MAX_TRGM_COUNT)
1749 3 : return false;
1750 :
1751 53 : trgmNFA->totalTrgmCount = (int) totalTrgmCount;
1752 :
1753 : /*
1754 : * Sort color trigrams by colors (will be useful for bsearch in packGraph)
1755 : * and enumerate the color trigrams that are expanded.
1756 : */
1757 53 : cnumber = 0;
1758 53 : qsort(colorTrgms, trgmNFA->colorTrgmsCount, sizeof(ColorTrgmInfo),
1759 : colorTrgmInfoCmp);
1760 328 : for (i = 0; i < trgmNFA->colorTrgmsCount; i++)
1761 : {
1762 275 : if (colorTrgms[i].expanded)
1763 : {
1764 160 : colorTrgms[i].cnumber = cnumber;
1765 160 : cnumber++;
1766 : }
1767 : }
1768 :
1769 53 : return true;
1770 : }
1771 :
1772 : /*
1773 : * Expand selected color trigrams into regular trigrams.
1774 : *
1775 : * Returns the TRGM array to be passed to the index machinery.
1776 : * The array must be allocated in rcontext.
1777 : */
1778 : static TRGM *
1779 53 : expandColorTrigrams(TrgmNFA *trgmNFA, MemoryContext rcontext)
1780 : {
1781 : TRGM *trg;
1782 : trgm *p;
1783 : int i;
1784 : TrgmColorInfo blankColor;
1785 : trgm_mb_char blankChar;
1786 :
1787 : /* Set up "blank" color structure containing a single zero character */
1788 53 : memset(blankChar.bytes, 0, sizeof(blankChar.bytes));
1789 53 : blankColor.wordCharsCount = 1;
1790 53 : blankColor.wordChars = &blankChar;
1791 :
1792 : /* Construct the trgm array */
1793 : trg = (TRGM *)
1794 53 : MemoryContextAllocZero(rcontext,
1795 : TRGMHDRSIZE +
1796 53 : trgmNFA->totalTrgmCount * sizeof(trgm));
1797 53 : trg->flag = ARRKEY;
1798 53 : SET_VARSIZE(trg, CALCGTSIZE(ARRKEY, trgmNFA->totalTrgmCount));
1799 53 : p = GETARR(trg);
1800 328 : for (i = 0; i < trgmNFA->colorTrgmsCount; i++)
1801 : {
1802 275 : ColorTrgmInfo *colorTrgm = &trgmNFA->colorTrgms[i];
1803 : TrgmColorInfo *c[3];
1804 : trgm_mb_char s[3];
1805 : int j,
1806 : i1,
1807 : i2,
1808 : i3;
1809 :
1810 : /* Ignore any unexpanded trigrams ... */
1811 275 : if (!colorTrgm->expanded)
1812 115 : continue;
1813 :
1814 : /* Get colors, substituting the dummy struct for COLOR_BLANK */
1815 640 : for (j = 0; j < 3; j++)
1816 : {
1817 480 : if (colorTrgm->ctrgm.colors[j] != COLOR_BLANK)
1818 413 : c[j] = &trgmNFA->colorInfo[colorTrgm->ctrgm.colors[j]];
1819 : else
1820 67 : c[j] = &blankColor;
1821 : }
1822 :
1823 : /* Iterate over all possible combinations of colors' characters */
1824 377 : for (i1 = 0; i1 < c[0]->wordCharsCount; i1++)
1825 : {
1826 217 : s[0] = c[0]->wordChars[i1];
1827 728 : for (i2 = 0; i2 < c[1]->wordCharsCount; i2++)
1828 : {
1829 511 : s[1] = c[1]->wordChars[i2];
1830 1970 : for (i3 = 0; i3 < c[2]->wordCharsCount; i3++)
1831 : {
1832 1459 : s[2] = c[2]->wordChars[i3];
1833 1459 : fillTrgm(p, s);
1834 1459 : p++;
1835 : }
1836 : }
1837 : }
1838 : }
1839 :
1840 53 : return trg;
1841 : }
1842 :
1843 : /*
1844 : * Convert trigram into trgm datatype.
1845 : */
1846 : static void
1847 1459 : fillTrgm(trgm *ptrgm, trgm_mb_char s[3])
1848 : {
1849 : char str[3 * MAX_MULTIBYTE_CHAR_LEN],
1850 : *p;
1851 : int i,
1852 : j;
1853 :
1854 : /* Write multibyte string into "str" (we don't need null termination) */
1855 1459 : p = str;
1856 :
1857 5836 : for (i = 0; i < 3; i++)
1858 : {
1859 4377 : if (s[i].bytes[0] != 0)
1860 : {
1861 8232 : for (j = 0; j < MAX_MULTIBYTE_CHAR_LEN && s[i].bytes[j]; j++)
1862 4116 : *p++ = s[i].bytes[j];
1863 : }
1864 : else
1865 : {
1866 : /* Emit a space in place of COLOR_BLANK */
1867 261 : *p++ = ' ';
1868 : }
1869 : }
1870 :
1871 : /* Convert "str" to a standard trigram (possibly hashing it) */
1872 1459 : compact_trigram(ptrgm, str, p - str);
1873 1459 : }
1874 :
1875 : /*
1876 : * Merge two states of graph.
1877 : */
1878 : static void
1879 103 : mergeStates(TrgmState *state1, TrgmState *state2)
1880 : {
1881 : Assert(state1 != state2);
1882 : Assert(!state1->parent);
1883 : Assert(!state2->parent);
1884 :
1885 : /* state1 absorbs state2's flags */
1886 103 : state1->flags |= state2->flags;
1887 :
1888 : /* state2, and indirectly all its children, become children of state1 */
1889 103 : state2->parent = state1;
1890 103 : }
1891 :
1892 : /*
1893 : * Compare function for sorting of color trigrams by their colors.
1894 : */
1895 : static int
1896 5089 : colorTrgmInfoCmp(const void *p1, const void *p2)
1897 : {
1898 5089 : const ColorTrgmInfo *c1 = (const ColorTrgmInfo *) p1;
1899 5089 : const ColorTrgmInfo *c2 = (const ColorTrgmInfo *) p2;
1900 :
1901 5089 : return memcmp(&c1->ctrgm, &c2->ctrgm, sizeof(ColorTrgm));
1902 : }
1903 :
1904 : /*
1905 : * Compare function for sorting color trigrams in descending order of
1906 : * their penalty fields.
1907 : */
1908 : static int
1909 423 : colorTrgmInfoPenaltyCmp(const void *p1, const void *p2)
1910 : {
1911 423 : float4 penalty1 = ((const ColorTrgmInfo *) p1)->penalty;
1912 423 : float4 penalty2 = ((const ColorTrgmInfo *) p2)->penalty;
1913 :
1914 423 : if (penalty1 < penalty2)
1915 127 : return 1;
1916 296 : else if (penalty1 == penalty2)
1917 162 : return 0;
1918 : else
1919 134 : return -1;
1920 : }
1921 :
1922 :
1923 : /*---------------------
1924 : * Subroutines for packing the graph into final representation (stage 4).
1925 : *---------------------
1926 : */
1927 :
1928 : /*
1929 : * Pack expanded graph into final representation.
1930 : *
1931 : * The result data must be allocated in rcontext.
1932 : */
1933 : static TrgmPackedGraph *
1934 53 : packGraph(TrgmNFA *trgmNFA, MemoryContext rcontext)
1935 : {
1936 53 : int snumber = 2,
1937 : arcIndex,
1938 : arcsCount;
1939 : HASH_SEQ_STATUS scan_status;
1940 : TrgmState *state;
1941 : TrgmPackArcInfo *arcs;
1942 : TrgmPackedArc *packedArcs;
1943 : TrgmPackedGraph *result;
1944 : int i,
1945 : j;
1946 :
1947 : /* Enumerate surviving states, giving init and fin reserved numbers */
1948 53 : hash_seq_init(&scan_status, trgmNFA->states);
1949 755 : while ((state = (TrgmState *) hash_seq_search(&scan_status)) != NULL)
1950 : {
1951 971 : while (state->parent)
1952 322 : state = state->parent;
1953 :
1954 649 : if (state->snumber < 0)
1955 : {
1956 546 : if (state->flags & TSTATE_INIT)
1957 53 : state->snumber = 0;
1958 493 : else if (state->flags & TSTATE_FIN)
1959 57 : state->snumber = 1;
1960 : else
1961 : {
1962 436 : state->snumber = snumber;
1963 436 : snumber++;
1964 : }
1965 : }
1966 : }
1967 :
1968 : /* Collect array of all arcs */
1969 53 : arcs = palloc_array(TrgmPackArcInfo, trgmNFA->arcsCount);
1970 53 : arcIndex = 0;
1971 53 : hash_seq_init(&scan_status, trgmNFA->states);
1972 702 : while ((state = (TrgmState *) hash_seq_search(&scan_status)) != NULL)
1973 : {
1974 649 : TrgmState *source = state;
1975 : ListCell *cell;
1976 :
1977 971 : while (source->parent)
1978 322 : source = source->parent;
1979 :
1980 1372 : foreach(cell, state->arcs)
1981 : {
1982 723 : TrgmArc *arc = (TrgmArc *) lfirst(cell);
1983 723 : TrgmState *target = arc->target;
1984 :
1985 1352 : while (target->parent)
1986 629 : target = target->parent;
1987 :
1988 723 : if (source->snumber != target->snumber)
1989 : {
1990 : ColorTrgmInfo *ctrgm;
1991 :
1992 566 : ctrgm = (ColorTrgmInfo *) bsearch(&arc->ctrgm,
1993 566 : trgmNFA->colorTrgms,
1994 566 : trgmNFA->colorTrgmsCount,
1995 : sizeof(ColorTrgmInfo),
1996 : colorTrgmInfoCmp);
1997 : Assert(ctrgm != NULL);
1998 : Assert(ctrgm->expanded);
1999 :
2000 566 : arcs[arcIndex].sourceState = source->snumber;
2001 566 : arcs[arcIndex].targetState = target->snumber;
2002 566 : arcs[arcIndex].colorTrgm = ctrgm->cnumber;
2003 566 : arcIndex++;
2004 : }
2005 : }
2006 : }
2007 :
2008 : /* Sort arcs to ease duplicate detection */
2009 53 : qsort(arcs, arcIndex, sizeof(TrgmPackArcInfo), packArcInfoCmp);
2010 :
2011 : /* We could have duplicates because states were merged. Remove them. */
2012 53 : if (arcIndex > 1)
2013 : {
2014 : /* p1 is probe point, p2 is last known non-duplicate. */
2015 : TrgmPackArcInfo *p1,
2016 : *p2;
2017 :
2018 31 : p2 = arcs;
2019 546 : for (p1 = arcs + 1; p1 < arcs + arcIndex; p1++)
2020 : {
2021 515 : if (packArcInfoCmp(p1, p2) > 0)
2022 : {
2023 509 : p2++;
2024 509 : *p2 = *p1;
2025 : }
2026 : }
2027 31 : arcsCount = (p2 - arcs) + 1;
2028 : }
2029 : else
2030 22 : arcsCount = arcIndex;
2031 :
2032 : /* Create packed representation */
2033 : result = (TrgmPackedGraph *)
2034 53 : MemoryContextAlloc(rcontext, sizeof(TrgmPackedGraph));
2035 :
2036 : /* Pack color trigrams information */
2037 53 : result->colorTrigramsCount = 0;
2038 328 : for (i = 0; i < trgmNFA->colorTrgmsCount; i++)
2039 : {
2040 275 : if (trgmNFA->colorTrgms[i].expanded)
2041 160 : result->colorTrigramsCount++;
2042 : }
2043 53 : result->colorTrigramGroups = (int *)
2044 53 : MemoryContextAlloc(rcontext, sizeof(int) * result->colorTrigramsCount);
2045 53 : j = 0;
2046 328 : for (i = 0; i < trgmNFA->colorTrgmsCount; i++)
2047 : {
2048 275 : if (trgmNFA->colorTrgms[i].expanded)
2049 : {
2050 160 : result->colorTrigramGroups[j] = trgmNFA->colorTrgms[i].count;
2051 160 : j++;
2052 : }
2053 : }
2054 :
2055 : /* Pack states and arcs information */
2056 53 : result->statesCount = snumber;
2057 53 : result->states = (TrgmPackedState *)
2058 53 : MemoryContextAlloc(rcontext, snumber * sizeof(TrgmPackedState));
2059 : packedArcs = (TrgmPackedArc *)
2060 53 : MemoryContextAlloc(rcontext, arcsCount * sizeof(TrgmPackedArc));
2061 53 : j = 0;
2062 595 : for (i = 0; i < snumber; i++)
2063 : {
2064 542 : int cnt = 0;
2065 :
2066 542 : result->states[i].arcs = &packedArcs[j];
2067 1102 : while (j < arcsCount && arcs[j].sourceState == i)
2068 : {
2069 560 : packedArcs[j].targetState = arcs[j].targetState;
2070 560 : packedArcs[j].colorTrgm = arcs[j].colorTrgm;
2071 560 : cnt++;
2072 560 : j++;
2073 : }
2074 542 : result->states[i].arcsCount = cnt;
2075 : }
2076 :
2077 : /* Allocate working memory for trigramsMatchGraph() */
2078 53 : result->colorTrigramsActive = (bool *)
2079 53 : MemoryContextAlloc(rcontext, sizeof(bool) * result->colorTrigramsCount);
2080 53 : result->statesActive = (bool *)
2081 53 : MemoryContextAlloc(rcontext, sizeof(bool) * result->statesCount);
2082 53 : result->statesQueue = (int *)
2083 53 : MemoryContextAlloc(rcontext, sizeof(int) * result->statesCount);
2084 :
2085 53 : return result;
2086 : }
2087 :
2088 : /*
2089 : * Comparison function for sorting TrgmPackArcInfos.
2090 : *
2091 : * Compares arcs in following order: sourceState, colorTrgm, targetState.
2092 : */
2093 : static int
2094 4546 : packArcInfoCmp(const void *a1, const void *a2)
2095 : {
2096 4546 : const TrgmPackArcInfo *p1 = (const TrgmPackArcInfo *) a1;
2097 4546 : const TrgmPackArcInfo *p2 = (const TrgmPackArcInfo *) a2;
2098 :
2099 4546 : if (p1->sourceState < p2->sourceState)
2100 2179 : return -1;
2101 2367 : if (p1->sourceState > p2->sourceState)
2102 2050 : return 1;
2103 317 : if (p1->colorTrgm < p2->colorTrgm)
2104 198 : return -1;
2105 119 : if (p1->colorTrgm > p2->colorTrgm)
2106 107 : return 1;
2107 12 : if (p1->targetState < p2->targetState)
2108 0 : return -1;
2109 12 : if (p1->targetState > p2->targetState)
2110 0 : return 1;
2111 12 : return 0;
2112 : }
2113 :
2114 :
2115 : /*---------------------
2116 : * Debugging functions
2117 : *
2118 : * These are designed to emit GraphViz files.
2119 : *---------------------
2120 : */
2121 :
2122 : #ifdef TRGM_REGEXP_DEBUG
2123 :
2124 : /*
2125 : * Print initial NFA, in regexp library's representation
2126 : */
2127 : static void
2128 : printSourceNFA(regex_t *regex, TrgmColorInfo *colors, int ncolors)
2129 : {
2130 : StringInfoData buf;
2131 : int nstates = pg_reg_getnumstates(regex);
2132 :
2133 : initStringInfo(&buf);
2134 :
2135 : appendStringInfoString(&buf, "\ndigraph sourceNFA {\n");
2136 :
2137 : for (int state = 0; state < nstates; state++)
2138 : {
2139 : regex_arc_t *arcs;
2140 : int arcsCount;
2141 :
2142 : appendStringInfo(&buf, "s%d", state);
2143 : if (pg_reg_getfinalstate(regex) == state)
2144 : appendStringInfoString(&buf, " [shape = doublecircle]");
2145 : appendStringInfoString(&buf, ";\n");
2146 :
2147 : arcsCount = pg_reg_getnumoutarcs(regex, state);
2148 : arcs = palloc_array(regex_arc_t, arcsCount);
2149 : pg_reg_getoutarcs(regex, state, arcs, arcsCount);
2150 :
2151 : for (int i = 0; i < arcsCount; i++)
2152 : {
2153 : appendStringInfo(&buf, " s%d -> s%d [label = \"%d\"];\n",
2154 : state, arcs[i].to, arcs[i].co);
2155 : }
2156 :
2157 : pfree(arcs);
2158 : }
2159 :
2160 : appendStringInfoString(&buf, " node [shape = point ]; initial;\n");
2161 : appendStringInfo(&buf, " initial -> s%d;\n",
2162 : pg_reg_getinitialstate(regex));
2163 :
2164 : /* Print colors */
2165 : appendStringInfoString(&buf, " { rank = sink;\n");
2166 : appendStringInfoString(&buf, " Colors [shape = none, margin=0, label=<\n");
2167 :
2168 : for (int i = 0; i < ncolors; i++)
2169 : {
2170 : TrgmColorInfo *color = &colors[i];
2171 :
2172 : appendStringInfo(&buf, "<br/>Color %d: ", i);
2173 : if (color->expandable)
2174 : {
2175 : for (int j = 0; j < color->wordCharsCount; j++)
2176 : {
2177 : char s[MAX_MULTIBYTE_CHAR_LEN + 1];
2178 :
2179 : memcpy(s, color->wordChars[j].bytes, MAX_MULTIBYTE_CHAR_LEN);
2180 : s[MAX_MULTIBYTE_CHAR_LEN] = '\0';
2181 : appendStringInfoString(&buf, s);
2182 : }
2183 : }
2184 : else
2185 : appendStringInfoString(&buf, "not expandable");
2186 : appendStringInfoChar(&buf, '\n');
2187 : }
2188 :
2189 : appendStringInfoString(&buf, " >];\n");
2190 : appendStringInfoString(&buf, " }\n");
2191 : appendStringInfoString(&buf, "}\n");
2192 :
2193 : {
2194 : /* dot -Tpng -o /tmp/source.png < /tmp/source.gv */
2195 : FILE *fp = fopen("/tmp/source.gv", "w");
2196 :
2197 : fprintf(fp, "%s", buf.data);
2198 : fclose(fp);
2199 : }
2200 :
2201 : pfree(buf.data);
2202 : }
2203 :
2204 : /*
2205 : * Print expanded graph.
2206 : */
2207 : static void
2208 : printTrgmNFA(TrgmNFA *trgmNFA)
2209 : {
2210 : StringInfoData buf;
2211 : HASH_SEQ_STATUS scan_status;
2212 : TrgmState *state;
2213 : TrgmState *initstate = NULL;
2214 :
2215 : initStringInfo(&buf);
2216 :
2217 : appendStringInfoString(&buf, "\ndigraph transformedNFA {\n");
2218 :
2219 : hash_seq_init(&scan_status, trgmNFA->states);
2220 : while ((state = (TrgmState *) hash_seq_search(&scan_status)) != NULL)
2221 : {
2222 : ListCell *cell;
2223 :
2224 : appendStringInfo(&buf, "s%d", -state->snumber);
2225 : if (state->flags & TSTATE_FIN)
2226 : appendStringInfoString(&buf, " [shape = doublecircle]");
2227 : if (state->flags & TSTATE_INIT)
2228 : initstate = state;
2229 : appendStringInfo(&buf, " [label = \"%d\"]", state->stateKey.nstate);
2230 : appendStringInfoString(&buf, ";\n");
2231 :
2232 : foreach(cell, state->arcs)
2233 : {
2234 : TrgmArc *arc = (TrgmArc *) lfirst(cell);
2235 :
2236 : appendStringInfo(&buf, " s%d -> s%d [label = \"",
2237 : -state->snumber, -arc->target->snumber);
2238 : printTrgmColor(&buf, arc->ctrgm.colors[0]);
2239 : appendStringInfoChar(&buf, ' ');
2240 : printTrgmColor(&buf, arc->ctrgm.colors[1]);
2241 : appendStringInfoChar(&buf, ' ');
2242 : printTrgmColor(&buf, arc->ctrgm.colors[2]);
2243 : appendStringInfoString(&buf, "\"];\n");
2244 : }
2245 : }
2246 :
2247 : if (initstate)
2248 : {
2249 : appendStringInfoString(&buf, " node [shape = point ]; initial;\n");
2250 : appendStringInfo(&buf, " initial -> s%d;\n", -initstate->snumber);
2251 : }
2252 :
2253 : appendStringInfoString(&buf, "}\n");
2254 :
2255 : {
2256 : /* dot -Tpng -o /tmp/transformed.png < /tmp/transformed.gv */
2257 : FILE *fp = fopen("/tmp/transformed.gv", "w");
2258 :
2259 : fprintf(fp, "%s", buf.data);
2260 : fclose(fp);
2261 : }
2262 :
2263 : pfree(buf.data);
2264 : }
2265 :
2266 : /*
2267 : * Print a TrgmColor readably.
2268 : */
2269 : static void
2270 : printTrgmColor(StringInfo buf, TrgmColor co)
2271 : {
2272 : if (co == COLOR_UNKNOWN)
2273 : appendStringInfoChar(buf, 'u');
2274 : else if (co == COLOR_BLANK)
2275 : appendStringInfoChar(buf, 'b');
2276 : else
2277 : appendStringInfo(buf, "%d", (int) co);
2278 : }
2279 :
2280 : /*
2281 : * Print final packed representation of trigram-based expanded graph.
2282 : */
2283 : static void
2284 : printTrgmPackedGraph(TrgmPackedGraph *packedGraph, TRGM *trigrams)
2285 : {
2286 : StringInfoData buf;
2287 : trgm *p;
2288 : int i;
2289 :
2290 : initStringInfo(&buf);
2291 :
2292 : appendStringInfoString(&buf, "\ndigraph packedGraph {\n");
2293 :
2294 : for (i = 0; i < packedGraph->statesCount; i++)
2295 : {
2296 : TrgmPackedState *state = &packedGraph->states[i];
2297 : int j;
2298 :
2299 : appendStringInfo(&buf, " s%d", i);
2300 : if (i == 1)
2301 : appendStringInfoString(&buf, " [shape = doublecircle]");
2302 :
2303 : appendStringInfo(&buf, " [label = <s%d>];\n", i);
2304 :
2305 : for (j = 0; j < state->arcsCount; j++)
2306 : {
2307 : TrgmPackedArc *arc = &state->arcs[j];
2308 :
2309 : appendStringInfo(&buf, " s%d -> s%d [label = \"trigram %d\"];\n",
2310 : i, arc->targetState, arc->colorTrgm);
2311 : }
2312 : }
2313 :
2314 : appendStringInfoString(&buf, " node [shape = point ]; initial;\n");
2315 : appendStringInfo(&buf, " initial -> s%d;\n", 0);
2316 :
2317 : /* Print trigrams */
2318 : appendStringInfoString(&buf, " { rank = sink;\n");
2319 : appendStringInfoString(&buf, " Trigrams [shape = none, margin=0, label=<\n");
2320 :
2321 : p = GETARR(trigrams);
2322 : for (i = 0; i < packedGraph->colorTrigramsCount; i++)
2323 : {
2324 : int count = packedGraph->colorTrigramGroups[i];
2325 : int j;
2326 :
2327 : appendStringInfo(&buf, "<br/>Trigram %d: ", i);
2328 :
2329 : for (j = 0; j < count; j++)
2330 : {
2331 : if (j > 0)
2332 : appendStringInfoString(&buf, ", ");
2333 :
2334 : /*
2335 : * XXX This representation is nice only for all-ASCII trigrams.
2336 : */
2337 : appendStringInfo(&buf, "\"%c%c%c\"", (*p)[0], (*p)[1], (*p)[2]);
2338 : p++;
2339 : }
2340 : }
2341 :
2342 : appendStringInfoString(&buf, " >];\n");
2343 : appendStringInfoString(&buf, " }\n");
2344 : appendStringInfoString(&buf, "}\n");
2345 :
2346 : {
2347 : /* dot -Tpng -o /tmp/packed.png < /tmp/packed.gv */
2348 : FILE *fp = fopen("/tmp/packed.gv", "w");
2349 :
2350 : fprintf(fp, "%s", buf.data);
2351 : fclose(fp);
2352 : }
2353 :
2354 : pfree(buf.data);
2355 : }
2356 :
2357 : #endif /* TRGM_REGEXP_DEBUG */
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