editdistance.cc File Reference

Edit distance calculation algorithm. More...

#include <config.h>
#include "editdistance.h"
#include "omassert.h"
#include <algorithm>
#include <cstdlib>

Include dependency graph for editdistance.cc:

Go to the source code of this file.

Classes
struct	edist_seq< CHR >
class	edist_state< CHR >

Macros
#define	INF   1000000

Functions
template<class CHR >
static int	seqcmp_editdist (const CHR *ptr1, int len1, const CHR *ptr2, int len2, int max_distance)
int	edit_distance_unsigned (const unsigned *ptr1, int len1, const unsigned *ptr2, int len2, int max_distance)
	Calculate the edit distance between two sequences. More...

Detailed Description

Edit distance calculation algorithm.

Based on that described in:

"An extension of Ukkonen's enhanced dynamic programming ASM algorithm" by Hal Berghel, University of Arkansas and David Roach, Acxiom Corporation

http://berghel.net/publications/asm/asm.php

Definition in file editdistance.cc.

Macro Definition Documentation

INF

#define INF   1000000

Definition at line 137 of file editdistance.cc.

Referenced by edist_state< CHR >::edist_state().

Function Documentation

edit_distance_unsigned()

int edit_distance_unsigned	(	const unsigned *	ptr1,
		int	len1,
		const unsigned *	ptr2,
		int	len2,
		int	max_distance
	)

Calculate the edit distance between two sequences.

Edit distance is defined as the minimum number of edit operations required to move from one sequence to another. The edit operations considered are:

• Insertion of a character at an arbitrary position.
• Deletion of a character at an arbitrary position.
• Substitution of a character at an arbitrary position.
• Transposition of two neighbouring characters at an arbitrary position in the string.

Parameters

ptr1	A pointer to the start of the first sequence.
len1	The length of the first sequence.
ptr2	A pointer to the start of the second sequence.
len2	The length of the first sequence.
max_distance	The greatest edit distance that's interesting to us. If the true edit distance is > max_distance, any value > max_distance may be returned instead (which allows the edit distance algorithm to avoid work for poor matches).

Returns

The edit distance from one item to the other.

Definition at line 206 of file editdistance.cc.

Referenced by Xapian::Database::get_spelling_suggestion().

seqcmp_editdist()

template<class CHR >

static int seqcmp_editdist ( const CHR *  ptr1, int  len1, const CHR *  ptr2, int  len2, int  max_distance  )

static

Definition at line 169 of file editdistance.cc.

References edist_state< CHR >::edist_calc_f_kp(), and edist_state< CHR >::get_f_kp().