xapian-core  1.4.22
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

Definition in file editdistance.cc.

## ◆ INF

 #define INF   1000000

Definition at line 137 of file editdistance.cc.

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

## ◆ 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.