Chromium Code Reviews
chromiumcodereview-hr@appspot.gserviceaccount.com (chromiumcodereview-hr) | Please choose your nickname with Settings | Help | Chromium Project | Gerrit Changes | Sign out
(80)

Unified Diff: pkg/analysis_services/lib/src/correction/levenshtein.dart

Issue 484733003: Import analysis_services.dart into analysis_server.dart. (Closed) Base URL: https://dart.googlecode.com/svn/branches/bleeding_edge/dart
Patch Set: Created 6 years, 4 months ago
Use n/p to move between diff chunks; N/P to move between comments. Draft comments are only viewable by you.
Jump to:
View side-by-side diff with in-line comments
Download patch
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;
- }
-}
« no previous file with comments | « pkg/analysis_services/lib/src/correction/fix.dart ('k') | pkg/analysis_services/lib/src/correction/name_suggestion.dart » ('j') | no next file with comments »

Powered by Google App Engine
This is Rietveld 408576698