Compute covering offsets/lengths.

pkg/analysis_server/lib/src/services/correction/strings.dart

Index: pkg/analysis_server/lib/src/services/correction/strings.dart
diff --git a/pkg/analysis_server/lib/src/services/correction/strings.dart b/pkg/analysis_server/lib/src/services/correction/strings.dart
index c2ea6cbcb49b5395005f10e9132241192df26b74..1689c7c5727e95c537ada39923431340529f342e 100644
--- a/pkg/analysis_server/lib/src/services/correction/strings.dart
+++ b/pkg/analysis_server/lib/src/services/correction/strings.dart
@@ -41,6 +41,17 @@ int compareStrings(String a, String b) {
   return a.compareTo(b);
 }
 
+int countLeadingWhitespaces(String str) {
+  int i = 0;
+  for (; i < str.length; i++) {
+    int c = str.codeUnitAt(i);
+    if (!isWhitespace(c)) {
+      break;
+    }
+  }
+  return i;
+}
+
 /**
  * Counts how many times [sub] appears in [str].
  */
@@ -57,6 +68,17 @@ int countMatches(String str, String sub) {
   return count;
 }
 
+int countTrailingWhitespaces(String str) {
+  int i = 0;
+  for (; i < str.length; i++) {
+    int c = str.codeUnitAt(str.length - 1 - i);
+    if (!isWhitespace(c)) {
+      break;
+    }
+  }
+  return i;
+}
+
 /**
  * Returns the number of characters common to the end of [a] and the start
  * of [b].