/*
** 2008 Nov 28
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
******************************************************************************
**
*/

#include "fts3_tokenizer.h"
#include "sqlite3.h"

/*
** The following describes the syntax supported by the fts3 MATCH
** operator in a similar format to that used by the lemon parser
** generator. This module does not use actually lemon, it uses a
** custom parser.
**
**   phrase ::= TOKEN.
**   phrase ::= TOKEN:COLUMN.
**   phrase ::= "TOKEN TOKEN TOKEN...".
**   phrase ::= phrase near phrase.
**
**   near ::= NEAR.
**   near ::= NEAR / INTEGER.
**
**   query ::= -TOKEN.
**   query ::= phrase.
**   query ::= LP query RP.
**   query ::= query NOT query.
**   query ::= query OR query.
**   query ::= query AND query.
*/

typedef struct Fts3Expr Fts3Expr;
typedef struct Fts3Phrase Fts3Phrase;

struct Fts3Phrase {
  int nToken;          /* Number of entries in aToken[] */
  int iColumn;         /* Index of column this phrase must match */
  int isNot;           /* Phrase prefixed by unary not (-) operator */
  struct PhraseToken {
    char *z;
    int n;             /* Number of bytes in buffer pointed to by z */
    int isPrefix;      /* True if token ends in with a "*" character */
  } aToken[1];
};

struct Fts3Expr {
  int eType;                 /* One of the FTSQUERY_XXX values defined below */
  int nNear;                 /* Valid if eType==FTSQUERY_NEAR */
  Fts3Expr *pParent;
  Fts3Expr *pLeft;
  Fts3Expr *pRight;
  Fts3Phrase *pPhrase;       /* Valid if eType==FTSQUERY_PHRASE */
};

int sqlite3Fts3ExprParse(sqlite3_tokenizer *, char **, int, int, 
                         const char *, int, Fts3Expr **);
void sqlite3Fts3ExprFree(Fts3Expr *);

/*
** Candidate values for Fts3Query.eType. Note that the order of the first
** four values is in order of precedence when parsing expressions. For 
** example, the following:
**
**   "a OR b AND c NOT d NEAR e"
**
** is equivalent to:
**
**   "a OR (b AND (c NOT (d NEAR e)))"
*/
#define FTSQUERY_NEAR   1
#define FTSQUERY_NOT    2
#define FTSQUERY_AND    3
#define FTSQUERY_OR     4
#define FTSQUERY_PHRASE 5

#ifdef SQLITE_TEST
void sqlite3Fts3ExprInitTestInterface(sqlite3 *db);
#endif