ts_utils.h

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/*-------------------------------------------------------------------------
 *
 * ts_utils.h
 *    helper utilities for tsearch
 *
 * Copyright (c) 1998-2020, PostgreSQL Global Development Group
 *
 * src/include/tsearch/ts_utils.h
 *
 *-------------------------------------------------------------------------
 */
#ifndef _PG_TS_UTILS_H_
#define _PG_TS_UTILS_H_

#include "nodes/pg_list.h"
#include "tsearch/ts_public.h"
#include "tsearch/ts_type.h"

/*
 * Common parse definitions for tsvector and tsquery
 */

/* tsvector parser support. */

struct TSVectorParseStateData;  /* opaque struct in tsvector_parser.c */
typedef struct TSVectorParseStateData *TSVectorParseState;

#define P_TSV_OPR_IS_DELIM  (1 << 0)
#define P_TSV_IS_TSQUERY    (1 << 1)
#define P_TSV_IS_WEB        (1 << 2)

extern TSVectorParseState init_tsvector_parser(char *input, int flags);
extern void reset_tsvector_parser(TSVectorParseState state, char *input);
extern bool gettoken_tsvector(TSVectorParseState state,
                              char **token, int *len,
                              WordEntryPos **pos, int *poslen,
                              char **endptr);
extern void close_tsvector_parser(TSVectorParseState state);

/* phrase operator begins with '<' */
#define ISOPERATOR(x) \
    ( pg_mblen(x) == 1 && ( *(x) == '!' ||  \
                            *(x) == '&' ||  \
                            *(x) == '|' ||  \
                            *(x) == '(' ||  \
                            *(x) == ')' ||  \
                            *(x) == '<'     \
                          ) )

/* parse_tsquery */

struct TSQueryParserStateData;  /* private in backend/utils/adt/tsquery.c */
typedef struct TSQueryParserStateData *TSQueryParserState;

typedef void (*PushFunction) (Datum opaque, TSQueryParserState state,
                              char *token, int tokenlen,
                              int16 tokenweights,   /* bitmap as described in
                                                     * QueryOperand struct */
                              bool prefix);

#define P_TSQ_PLAIN     (1 << 0)
#define P_TSQ_WEB       (1 << 1)

extern TSQuery parse_tsquery(char *buf,
                             PushFunction pushval,
                             Datum opaque,
                             int flags);

/* Functions for use by PushFunction implementations */
extern void pushValue(TSQueryParserState state,
                      char *strval, int lenval, int16 weight, bool prefix);
extern void pushStop(TSQueryParserState state);
extern void pushOperator(TSQueryParserState state, int8 oper, int16 distance);

/*
 * parse plain text and lexize words
 */
typedef struct
{
    uint16      len;
    uint16      nvariant;
    union
    {
        uint16      pos;

        /*
         * When apos array is used, apos[0] is the number of elements in the
         * array (excluding apos[0]), and alen is the allocated size of the
         * array.
         */
        uint16     *apos;
    }           pos;
    uint16      flags;          /* currently, only TSL_PREFIX */
    char       *word;
    uint32      alen;
} ParsedWord;

typedef struct
{
    ParsedWord *words;
    int32       lenwords;
    int32       curwords;
    int32       pos;
} ParsedText;

extern void parsetext(Oid cfgId, ParsedText *prs, char *buf, int32 buflen);

/*
 * headline framework, flow in common to generate:
 *  1 parse text with hlparsetext
 *  2 parser-specific function to find part
 *  3 generateHeadline to generate result text
 */

extern void hlparsetext(Oid cfgId, HeadlineParsedText *prs, TSQuery query,
                        char *buf, int32 buflen);
extern text *generateHeadline(HeadlineParsedText *prs);

/*
 * TSQuery execution support
 *
 * TS_execute() executes a tsquery against data that can be represented in
 * various forms.  The TSExecuteCallback callback function is called to check
 * whether a given primitive tsquery value is matched in the data.
 */

/* TS_execute requires ternary logic to handle NOT with phrase matches */
typedef enum
{
    TS_NO,                      /* definitely no match */
    TS_YES,                     /* definitely does match */
    TS_MAYBE                    /* can't verify match for lack of pos data */
} TSTernaryValue;

/*
 * struct ExecPhraseData is passed to a TSExecuteCallback function if we need
 * lexeme position data (because of a phrase-match operator in the tsquery).
 * The callback should fill in position data when it returns TS_YES (success).
 * If it cannot return position data, it should leave "data" unchanged and
 * return TS_MAYBE.  The caller of TS_execute() must then arrange for a later
 * recheck with position data available.
 *
 * The reported lexeme positions must be sorted and unique.  Callers must only
 * consult the position bits of the pos array, ie, WEP_GETPOS(data->pos[i]).
 * This allows the returned "pos" to point directly to the WordEntryPos
 * portion of a tsvector value.  If "allocated" is true then the pos array
 * is palloc'd workspace and caller may free it when done.
 *
 * "negate" means that the pos array contains positions where the query does
 * not match, rather than positions where it does.  "width" is positive when
 * the match is wider than one lexeme.  Neither of these fields normally need
 * to be touched by TSExecuteCallback functions; they are used for
 * phrase-search processing within TS_execute.
 *
 * All fields of the ExecPhraseData struct are initially zeroed by caller.
 */
typedef struct ExecPhraseData
{
    int         npos;           /* number of positions reported */
    bool        allocated;      /* pos points to palloc'd data? */
    bool        negate;         /* positions are where query is NOT matched */
    WordEntryPos *pos;          /* ordered, non-duplicate lexeme positions */
    int         width;          /* width of match in lexemes, less 1 */
} ExecPhraseData;

/*
 * Signature for TSQuery lexeme check functions
 *
 * arg: opaque value passed through from caller of TS_execute
 * val: lexeme to test for presence of
 * data: to be filled with lexeme positions; NULL if position data not needed
 *
 * Return TS_YES if lexeme is present in data, TS_MAYBE if it might be
 * present, TS_NO if it definitely is not present.  If data is not NULL,
 * it must be filled with lexeme positions if available.  If position data
 * is not available, leave *data as zeroes and return TS_MAYBE, never TS_YES.
 */
typedef TSTernaryValue (*TSExecuteCallback) (void *arg, QueryOperand *val,
                                             ExecPhraseData *data);

/*
 * Flag bits for TS_execute
 */
#define TS_EXEC_EMPTY           (0x00)
/*
 * If TS_EXEC_SKIP_NOT is set, then NOT sub-expressions are automatically
 * evaluated to be true.  This was formerly the default behavior.  It's now
 * deprecated because it tends to give silly answers, but some applications
 * might still have a use for it.
 */
#define TS_EXEC_SKIP_NOT        (0x01)
/*
 * If TS_EXEC_PHRASE_NO_POS is set, allow OP_PHRASE to be executed lossily
 * in the absence of position information: a true result indicates that the
 * phrase might be present.  Without this flag, OP_PHRASE always returns
 * false if lexeme position information is not available.
 */
#define TS_EXEC_PHRASE_NO_POS   (0x02)

extern bool TS_execute(QueryItem *curitem, void *arg, uint32 flags,
                       TSExecuteCallback chkcond);
extern bool tsquery_requires_match(QueryItem *curitem);

/*
 * to_ts* - text transformation to tsvector, tsquery
 */
extern TSVector make_tsvector(ParsedText *prs);
extern int32 tsCompareString(char *a, int lena, char *b, int lenb, bool prefix);

/*
 * Possible strategy numbers for indexes
 *    TSearchStrategyNumber  - (tsvector|text) @@ tsquery
 *    TSearchWithClassStrategyNumber  - tsvector @@@ tsquery
 */
#define TSearchStrategyNumber           1
#define TSearchWithClassStrategyNumber  2

/*
 * TSQuery Utilities
 */
extern QueryItem *clean_NOT(QueryItem *ptr, int32 *len);
extern TSQuery cleanup_tsquery_stopwords(TSQuery in);

typedef struct QTNode
{
    QueryItem  *valnode;
    uint32      flags;
    int32       nchild;
    char       *word;
    uint32      sign;
    struct QTNode **child;
} QTNode;

/* bits in QTNode.flags */
#define QTN_NEEDFREE    0x01
#define QTN_NOCHANGE    0x02
#define QTN_WORDFREE    0x04

typedef uint64 TSQuerySign;

#define TSQS_SIGLEN  (sizeof(TSQuerySign)*BITS_PER_BYTE)

#define TSQuerySignGetDatum(X)      Int64GetDatum((int64) (X))
#define DatumGetTSQuerySign(X)      ((TSQuerySign) DatumGetInt64(X))
#define PG_RETURN_TSQUERYSIGN(X)    return TSQuerySignGetDatum(X)
#define PG_GETARG_TSQUERYSIGN(n)    DatumGetTSQuerySign(PG_GETARG_DATUM(n))


extern QTNode *QT2QTN(QueryItem *in, char *operand);
extern TSQuery QTN2QT(QTNode *in);
extern void QTNFree(QTNode *in);
extern void QTNSort(QTNode *in);
extern void QTNTernary(QTNode *in);
extern void QTNBinary(QTNode *in);
extern int  QTNodeCompare(QTNode *an, QTNode *bn);
extern QTNode *QTNCopy(QTNode *in);
extern void QTNClearFlags(QTNode *in, uint32 flags);
extern bool QTNEq(QTNode *a, QTNode *b);
extern TSQuerySign makeTSQuerySign(TSQuery a);
extern QTNode *findsubquery(QTNode *root, QTNode *ex, QTNode *subs,
                            bool *isfind);

#endif                          /* _PG_TS_UTILS_H_ */