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