97 lines
2.9 KiB
C
97 lines
2.9 KiB
C
/*
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** 2008 Nov 28
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**
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** The author disclaims copyright to this source code. In place of
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** a legal notice, here is a blessing:
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**
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** May you do good and not evil.
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** May you find forgiveness for yourself and forgive others.
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** May you share freely, never taking more than you give.
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**
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******************************************************************************
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**
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*/
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#include "fts3_tokenizer.h"
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#include "sqlite3.h"
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/*
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** The following describes the syntax supported by the fts3 MATCH
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** operator in a similar format to that used by the lemon parser
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** generator. This module does not use actually lemon, it uses a
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** custom parser.
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**
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** query ::= andexpr (OR andexpr)*.
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**
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** andexpr ::= notexpr (AND? notexpr)*.
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**
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** notexpr ::= nearexpr (NOT nearexpr|-TOKEN)*.
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** notexpr ::= LP query RP.
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**
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** nearexpr ::= phrase (NEAR distance_opt nearexpr)*.
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**
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** distance_opt ::= .
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** distance_opt ::= / INTEGER.
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**
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** phrase ::= TOKEN.
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** phrase ::= COLUMN:TOKEN.
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** phrase ::= "TOKEN TOKEN TOKEN...".
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*/
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typedef struct Fts3Expr Fts3Expr;
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typedef struct Fts3Phrase Fts3Phrase;
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/*
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** A "phrase" is a sequence of one or more tokens that must match in
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** sequence. A single token is the base case and the most common case.
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** For a sequence of tokens contained in "...", nToken will be the number
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** of tokens in the string.
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*/
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struct Fts3Phrase {
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int nToken; /* Number of tokens in the phrase */
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int iColumn; /* Index of column this phrase must match */
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int isNot; /* Phrase prefixed by unary not (-) operator */
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struct PhraseToken {
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char *z; /* Text of the token */
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int n; /* Number of bytes in buffer pointed to by z */
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int isPrefix; /* True if token ends in with a "*" character */
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} aToken[1]; /* One entry for each token in the phrase */
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};
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/*
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** A tree of these objects forms the RHS of a MATCH operator.
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*/
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struct Fts3Expr {
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int eType; /* One of the FTSQUERY_XXX values defined below */
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int nNear; /* Valid if eType==FTSQUERY_NEAR */
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Fts3Expr *pParent; /* pParent->pLeft==this or pParent->pRight==this */
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Fts3Expr *pLeft; /* Left operand */
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Fts3Expr *pRight; /* Right operand */
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Fts3Phrase *pPhrase; /* Valid if eType==FTSQUERY_PHRASE */
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};
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int sqlite3Fts3ExprParse(sqlite3_tokenizer *, char **, int, int,
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const char *, int, Fts3Expr **);
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void sqlite3Fts3ExprFree(Fts3Expr *);
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/*
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** Candidate values for Fts3Query.eType. Note that the order of the first
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** four values is in order of precedence when parsing expressions. For
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** example, the following:
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**
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** "a OR b AND c NOT d NEAR e"
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**
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** is equivalent to:
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**
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** "a OR (b AND (c NOT (d NEAR e)))"
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*/
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#define FTSQUERY_NEAR 1
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#define FTSQUERY_NOT 2
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#define FTSQUERY_AND 3
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#define FTSQUERY_OR 4
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#define FTSQUERY_PHRASE 5
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#ifdef SQLITE_TEST
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void sqlite3Fts3ExprInitTestInterface(sqlite3 *db);
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#endif
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