edit-distance.c.tmpl

#linein
#include <stdio.h>
#include <limits.h>
#include <stdlib.h>
#include <stdint.h>

#include "config.h"
#include "text-fuzzy.h"
#include "edit-distance-[% stem %].h"

int [% function %] (text_fuzzy_t * tf)
{
    const [% type %] * word1 = (const [% type %] *) tf->b.[% value %];
    int len1 = tf->b.[% length %];
    const [% type %] * word2 = (const [% type %] *) tf->text.[% value %];
    int len2 = tf->text.[% length %];
    /* Return value. */
    int d;
    /* X and Y coordinates in the matrix of strings. */
    int i;
    int j;
    /* Unfeasible value; indicates no match. */
    int large_value;
    int max;

    /* Matrix is the dynamic programming matrix. We economize on space
       by having only two columns. */

#ifdef STACKALLOCOK
    int matrix[2][len2 + 1];
#else
    int * matrix[2];
#endif

    tf->n_edit = 0;

    max = tf->max_distance;

#ifndef STACKALLOCOK
    for (i = 0; i < 2; i++) {
	CALLOC (matrix[i], len2 + 1, int);
    }
#endif

    /*
      Initialize the 0 row of "matrix".

        0  
        1  
        2  
        3  

     */

    if (max != NO_MAX_DISTANCE) {
        large_value = max + 1;
    }
    else {
        if (len2 > len1) {
            large_value = len2;
        }
        else {
            large_value = len1;
        }
    }

    for (j = 0; j <= len2; j++) {
        matrix[0][j] = j;
    }

    /* Loop over column. */
    for (i = 1; i <= len1; i++) {
        [% type %] c1;
        /* The first value to consider of the ith column. */
        int min_j;
        /* The last value to consider of the ith column. */
        int max_j;
        /* The smallest value of the matrix in the ith column. */
        int col_min;
        /* The next column of the matrix to fill in. */
        int next;
        /* The previously-filled-in column of the matrix. */
        int prev;

        c1 = word1[i-1];
        min_j = 1;
        max_j = len2;
	/* If we have a maximum permitted distance, we can set the
	   minimum and maximum columns to inspect to be smaller than
	   the smallest and largest values respectively. */
        if (max != NO_MAX_DISTANCE) {
            if (i > max) {
                min_j = i - max;
            }
            if (len2 > max + i) {
                max_j = max + i;
            }
        }
        col_min = INT_MAX;
        next = i % 2;
        if (next == 1) {
            prev = 0;
        }
        else {
            prev = 1;
        }
        matrix[next][0] = i;
        /* Loop over rows. */
        for (j = 1; j <= len2; j++) {
            if (j < min_j || j > max_j) {
                /* Put a large value in there. */
                matrix[next][j] = large_value;
            }
            else {
                [% type %] c2;

                c2 = word2[j - 1];
                if ([% compare_c1_c2 %]) {
                    /* The character at position i in word1 is the same as
                       the character at position j in word2. */
                    matrix[next][j] = matrix[prev][j - 1];
                }
                else {
                    /* The character at position i in word1 is not the
                       same as the character at position j in word2, so
                       work out what the minimum cost for getting to cell
                       i, j is. */
                    int delete;
                    int insert;
                    int substitute;
                    int minimum;

                    delete = matrix[prev][j] + [% delete_cost %];
                    insert = matrix[next][j-1] + [% insert_cost %];
                    substitute = matrix[prev][j-1] + [% substitute_cost %];
                    minimum = delete;
                    if (insert < minimum) {
                        minimum = insert;
                    }
                    if (substitute < minimum) {
                        minimum = substitute;
                    }
                    matrix[next][j] = minimum;
                }
            }
            /* Find the minimum value in the ith column. */
            if (matrix[next][j] < col_min) {
                col_min = matrix[next][j];
            }
        }
        if (max != NO_MAX_DISTANCE) {
            if (col_min > max) {
                /* All the elements of the ith column are greater than the
                   maximum, so no match less than or equal to max can be
                   found by looking at succeeding columns. */

		d = large_value;
		goto cleanup;
            }
        }
    }
    d = matrix[len1 % 2][len2];

    cleanup:

#ifndef STACKALLOCOK
    for (i = 0; i < 2; i++) {
	FREE (matrix[i]);
    }
#endif
    return d;
}