Index: pkg/analysis_services/lib/src/correction/levenshtein.dart |
diff --git a/pkg/analysis_services/lib/src/correction/levenshtein.dart b/pkg/analysis_services/lib/src/correction/levenshtein.dart |
deleted file mode 100644 |
index 31f17fd6f30a153b081cbf5a0f21d0967690b912..0000000000000000000000000000000000000000 |
--- a/pkg/analysis_services/lib/src/correction/levenshtein.dart |
+++ /dev/null |
@@ -1,131 +0,0 @@ |
-library levenshtein; |
- |
-import 'dart:math' as math; |
- |
-/** |
- * The value returned by [levenshtein] if the distance is determined |
- * to be over the specified threshold. |
- */ |
-const int LEVENSHTEIN_MAX = 1 << 20; |
- |
-const int _MAX_VALUE = 1 << 10; |
- |
-/** |
- * Find the Levenshtein distance between two [String]s if it's less than or |
- * equal to a given threshold. |
- * |
- * This is the number of changes needed to change one String into another, |
- * where each change is a single character modification (deletion, insertion or |
- * substitution). |
- * |
- * This implementation follows from Algorithms on Strings, Trees and Sequences |
- * by Dan Gusfield and Chas Emerick's implementation of the Levenshtein distance |
- * algorithm. |
- */ |
-int levenshtein(String s, String t, int threshold, {bool caseSensitive: true}) { |
- if (s == null || t == null) { |
- throw new ArgumentError('Strings must not be null'); |
- } |
- if (threshold < 0) { |
- throw new ArgumentError('Threshold must not be negative'); |
- } |
- |
- if (!caseSensitive) { |
- s = s.toLowerCase(); |
- t = t.toLowerCase(); |
- } |
- |
- int s_len = s.length; |
- int t_len = t.length; |
- |
- // if one string is empty, |
- // the edit distance is necessarily the length of the other |
- if (s_len == 0) { |
- return t_len <= threshold ? t_len : LEVENSHTEIN_MAX; |
- } |
- if (t_len == 0) { |
- return s_len <= threshold ? s_len : LEVENSHTEIN_MAX; |
- } |
- // the distance can never be less than abs(s_len - t_len) |
- if ((s_len - t_len).abs() > threshold) { |
- return LEVENSHTEIN_MAX; |
- } |
- |
- // swap the two strings to consume less memory |
- if (s_len > t_len) { |
- String tmp = s; |
- s = t; |
- t = tmp; |
- s_len = t_len; |
- t_len = t.length; |
- } |
- |
- // 'previous' cost array, horizontally |
- List<int> p = new List<int>.filled(s_len + 1, 0); |
- // cost array, horizontally |
- List<int> d = new List<int>.filled(s_len + 1, 0); |
- // placeholder to assist in swapping p and d |
- List<int> _d; |
- |
- // fill in starting table values |
- int boundary = math.min(s_len, threshold) + 1; |
- for (int i = 0; i < boundary; i++) { |
- p[i] = i; |
- } |
- |
- // these fills ensure that the value above the rightmost entry of our |
- // stripe will be ignored in following loop iterations |
- _setRange(p, boundary, p.length, _MAX_VALUE); |
- _setRange(d, 0, d.length, _MAX_VALUE); |
- |
- // iterates through t |
- for (int j = 1; j <= t_len; j++) { |
- // jth character of t |
- int t_j = t.codeUnitAt(j - 1); |
- d[0] = j; |
- |
- // compute stripe indices, constrain to array size |
- int min = math.max(1, j - threshold); |
- int max = math.min(s_len, j + threshold); |
- |
- // the stripe may lead off of the table if s and t are of different sizes |
- if (min > max) { |
- return LEVENSHTEIN_MAX; |
- } |
- |
- // ignore entry left of leftmost |
- if (min > 1) { |
- d[min - 1] = _MAX_VALUE; |
- } |
- |
- // iterates through [min, max] in s |
- for (int i = min; i <= max; i++) { |
- if (s.codeUnitAt(i - 1) == t_j) { |
- // diagonally left and up |
- d[i] = p[i - 1]; |
- } else { |
- // 1 + minimum of cell to the left, to the top, diagonally left and up |
- d[i] = 1 + math.min(math.min(d[i - 1], p[i]), p[i - 1]); |
- } |
- } |
- |
- // copy current distance counts to 'previous row' distance counts |
- _d = p; |
- p = d; |
- d = _d; |
- } |
- |
- // if p[n] is greater than the threshold, |
- // there's no guarantee on it being the correct distance |
- if (p[s_len] <= threshold) { |
- return p[s_len]; |
- } |
- |
- return LEVENSHTEIN_MAX; |
-} |
- |
-void _setRange(List<int> a, int start, int end, int value) { |
- for (int i = start; i < end; i++) { |
- a[i] = value; |
- } |
-} |