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