Remove unintentional dependency on analysis_server

pkg/analyzer_plugin/lib/src/utilities/string_utilities.dart

Index: pkg/analyzer_plugin/lib/src/utilities/string_utilities.dart
diff --git a/pkg/analyzer_plugin/lib/src/utilities/string_utilities.dart b/pkg/analyzer_plugin/lib/src/utilities/string_utilities.dart
new file mode 100644
index 0000000000000000000000000000000000000000..5c92f43e6e6bf7719bf9ed3d21ac3aa649427db7
--- /dev/null
+++ b/pkg/analyzer_plugin/lib/src/utilities/string_utilities.dart
@@ -0,0 +1,76 @@
+// Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:charcode/ascii.dart';
+
+/**
+ * Returns a list of the words from which the given camel case [string] is
+ * composed.
+ *
+ * 'getCamelWords' => ['get', 'Camel', 'Words']
+ * 'getHTMLText' => ['get', 'HTML', 'Text']
+ */
+List<String> getCamelWords(String string) {
+  if (string == null || string.isEmpty) {
+    return const <String>[];
+  }
+  List<String> parts = <String>[];
+  bool wasLowerCase = false;
+  bool wasUpperCase = false;
+  int wordStart = 0;
+  for (int i = 0; i < string.length; i++) {
+    int c = string.codeUnitAt(i);
+    var newLowerCase = isLowerCase(c);
+    var newUpperCase = isUpperCase(c);
+    // myWord
+    // | ^
+    if (wasLowerCase && newUpperCase) {
+      parts.add(string.substring(wordStart, i));
+      wordStart = i;
+    }
+    // myHTMLText
+    //   |   ^
+    if (wasUpperCase &&
+        newUpperCase &&
+        i + 1 < string.length &&
+        isLowerCase(string.codeUnitAt(i + 1))) {
+      parts.add(string.substring(wordStart, i));
+      wordStart = i;
+    }
+    wasLowerCase = newLowerCase;
+    wasUpperCase = newUpperCase;
+  }
+  parts.add(string.substring(wordStart));
+  return parts;
+}
+
+/**
+ * Return `true` if the given [string] is either `null` or empty.
+ */
+bool isEmpty(String string) => string == null || string.isEmpty;
+
+/**
+ * Return `true` if the given [character] is a lowercase ASCII character.
+ */
+bool isLowerCase(int character) => character >= $a && character <= $z;
+
+/**
+ * Return `true` if the given [character] is an uppercase ASCII character.
+ */
+bool isUpperCase(int character) => character >= $A && character <= $Z;
+
+/**
+ * If the given [string] starts with the text to [remove], then return the
+ * portion of the string after the text to remove. Otherwise, return the
+ * original string unmodified.
+ */
+String removeStart(String string, String remove) {
+  if (isEmpty(string) || isEmpty(remove)) {
+    return string;
+  }
+  if (string.startsWith(remove)) {
+    return string.substring(remove.length);
+  }
+  return string;
+}