vgram.h

/*-------------------------------------------------------------------------
 *
 * vgram.h
 *		Header for vgram module.
 *
 * Copyright (c) 2011-2017, Alexander Korotkov
 *
 * IDENTIFICATION
 *	  contrib/vgram/vgram.h
 *
 *-------------------------------------------------------------------------
 */
#ifndef _V_GRAM_H_
#define _V_GRAM_H_

#include "tsearch/ts_locale.h"

/*
 * V-gram parameters
 */
#define minQ						(2)
#define maxQ						(5)
#define isExtractable(c)			(t_isalpha(c) || t_isdigit(c))
#define VGRAM_LIMIT_RATIO			(0.005)
#define DEFAULT_CHARACTER_FREQUENCY	(0.001)
#define EMPTY_CHARACTER				('$')

/* strategy numbers */
#define LikeStrategyNumber			3
#define ILikeStrategyNumber			4


typedef void (*WordCallback) (const char *wordStart, const char *wordEnd, void *userData);
typedef void (*VGramCallBack) (char *vgram, void *userData);

typedef struct
{
	VGramCallBack	callback;
	void		   *userData;
} ExtractVGramsInfo;

extern void loadStats(void);
extern float4 estimateVGramSelectivilty(const char *vgram);
extern void extractMinimalVGramsWord(const char *wordStart, const char *wordEnd, void *userData);
extern void extractWords(const char *string, size_t len, WordCallback callback, void *userData);
extern void extractVGramsWord(const char *wordStart, const char *wordEnd, void *userData);
extern Datum *extractQueryLike(int32 *nentries, text *pattern);

#endif /* _V_GRAM_H_ */